Population density and suicide in Scotland.

PubMed

Stark, Cameron; Hopkins, Paddy; Gibbs, Diane; Belbin, Alan; Hay, Alistair

2007-01-01

Suicide rates among men have increased in Scotland while falling in neighbouring countries. A national suicide prevention strategy has been produced. Previous work found that some rural areas of Scotland had higher than average rates of male suicide and undetermined deaths. This article describes the association between population density and suicide and undetermined death rates in Scotland. Anonymised information on deaths from suicide and undetermined cause in Scotland were obtained from the General Registrar Office for 1981-1999, including information on postcode sector. Each postcode sector was assigned a deprivation and population density score. Loglinear models were used to examine the effects of time period (grouped into four periods), deprivation quintiles, population density (grouped into four categories) and their interactions in each sex in three age groups. A significance level of 5% was used throughout. Adjusted rate ratios and 95% confidence intervals were based on models that included only significant factors and interactions. In men, there were higher rate ratios in the most densely populated and least densely populated quartiles, with intermediate rate ratios in other areas. There was no association with population density in women aged less than 25 years, a similar pattern to men in 25-44 year old women, and lower rates in rural areas in older women. Higher levels of deprivation were associated with higher rate ratios of suicide in both sexes and all age groups. Rate ratios over time increased in younger men and women, remained stable in older men, and declined in older women. Deprivation is associated with higher rates of suicide and undetermined deaths at all levels of population density and in all age groups. The highest rates of suicide among men are in the most and least densely populated areas, after adjusting for deprivation. The effect is different among women, with no effect among younger women, and lower rates among older women in areas with lower population density.

Conservation threats due to human-caused increases in fire frequency in Mediterranean-climate ecosystems.

PubMed

Syphard, Alexandra D; Radeloff, Volker C; Hawbaker, Todd J; Stewart, Susan I

2009-06-01

Periodic wildfire is an important natural process in Mediterranean-climate ecosystems, but increasing fire recurrence threatens the fragile ecology of these regions. Because most fires are human-caused, we investigated how human population patterns affect fire frequency. Prior research in California suggests the relationship between population density and fire frequency is not linear. There are few human ignitions in areas with low population density, so fire frequency is low. As population density increases, human ignitions and fire frequency also increase, but beyond a density threshold, the relationship becomes negative as fuels become sparser and fire suppression resources are concentrated. We tested whether this hypothesis also applies to the other Mediterranean-climate ecosystems of the world. We used global satellite databases of population, fire activity, and land cover to evaluate the spatial relationship between humans and fire in the world's five Mediterranean-climate ecosystems. Both the mean and median population densities were consistently and substantially higher in areas with than without fire, but fire again peaked at intermediate population densities, which suggests that the spatial relationship is complex and nonlinear. Some land-cover types burned more frequently than expected, but no systematic differences were observed across the five regions. The consistent association between higher population densities and fire suggests that regardless of differences between land-cover types, natural fire regimes, or overall population, the presence of people in Mediterranean-climate regions strongly affects the frequency of fires; thus, population growth in areas now sparsely settled presents a conservation concern. Considering the sensitivity of plant species to repeated burning and the global conservation significance of Mediterranean-climate ecosystems, conservation planning needs to consider the human influence on fire frequency. Fine-scale spatial analysis of relationships between people and fire may help identify areas where increases in fire frequency will threaten ecologically valuable areas. ©2009 Society for Conservation Biology.

A common framework for conservation planning: Linking individual and metapopulation models [Chapter 7

Treesearch

Barry R. Noon; Kevin S. McKelvey

1996-01-01

Many populations exhibit pronounced spatial structure: dispersed areas of high population density embedded in areas of low density, with population centers connected through dispersal. This recognition has led many conservation biologists to embrace the metapopulation concept (Levins 1970) as the appropriate paradigm for reserve design structures (reviewed in Hanski...

Area characteristics and admission rates of people with schizophrenia and affective disorders in a German rural catchment area.

PubMed

Losert, C; Schmauß, M; Becker, T; Kilian, R

2012-12-01

Studies in urban areas identified environmental risk factors for mental illness, but little research on this topic has been performed in rural areas. Hospital admission rates were computed for 174 rural municipalities in the catchment area of the state psychiatric hospital in Günzburg in years 2006 to 2009 and combined with structural and socio-economic data. Relationships of overall and diagnosis-specific admission rates with municipality characteristics were analysed by means of negative binomial regression models. Admission rates of patients with a diagnosis of schizophrenia and affective disorder combined decrease with increasing population growth, population density, average income and green areas, while admission rates are positively correlated with commuter balance, income inequality, unemployment rates and traffic areas. Admission rates for schizophrenia are negatively related to population growth, average income and agricultural areas, but positively related to mobility index, income inequality and unemployment rate. Admission rates for affective disorders are negatively related to population growth, population density, average income and green areas, while higher admission rates are correlated with commuter balance, high income inequality, unemployment rate and traffic-related areas. Effects of wealth, economic inequality, population density and structural area characteristics influence psychiatric admission rates also in rural areas.

The association between ALS and population density: A population based study.

PubMed

Scott, Kirsten M; Abhinav, Kumar; Wijesekera, Lokesh; Ganesalingam, Jeban; Goldstein, Laura H; Janssen, Anna; Dougherty, Andrew; Willey, Emma; Stanton, Biba R; Turner, Martin R; Ampong, Mary-Ann; Sakel, Mohammed; Orrell, Richard; Howard, Robin; Shaw, Christopher E; Nigel Leigh, P; Al-Chalabi, Ammar

2010-10-01

We aimed to assess whether rural residence is associated with amyotrophic lateral sclerosis in the south-east of England using a population based register. Previous studies in different populations have produced contradictory findings. Residence defined by London borough or non-metropolitan district at time of diagnosis was recorded for each incident case in the South-East England ALS Register between 1995 and 2005. Each of the 26 boroughs or districts of the catchment area of the register was classified according to population density. Age- and sex-adjusted incidence of ALS was calculated for each region and the relationship with population density tested by linear regression, thereby controlling for the underlying population structure. We found that population density in region of residence at diagnosis explained 25% of the variance in ALS rates (r = 0.5, p < 0.01). Thus, in this cohort in the south-east of England, people with ALS were more likely to be resident in areas of high population density at diagnosis.

The association between ALS and population density: A population based study

PubMed Central

SCOTT, KIRSTEN M.; ABHINAV, KUMAR; WIJESEKERA, LOKESH; GANESALINGAM, JEBAN; GOLDSTEIN, LAURA H.; JANSSEN, ANNA; DOUGHERTY, ANDREW; WILLEY, EMMA; STANTON, BIBA R.; TURNER, MARTIN R.; AMPONG, MARY-ANN; SAKEL, MOHAMMED; ORRELL, RICHARD; HOWARD, ROBIN; SHAW, CHRISTOPHER E.; LEIGH, P. NIGEL; AL-CHALABI, AMMAR

2011-01-01

We aimed to assess whether rural residence is associated with amyotrophic lateral sclerosis in the south-east of England using a population based register. Previous studies in different populations have produced contradictory findings. Residence defined by London borough or non-metropolitan district at time of diagnosis was recorded for each incident case in the South-East England ALS Register between 1995 and 2005. Each of the 26 boroughs or districts of the catchment area of the register was classified according to population density. Age- and sex-adjusted incidence of ALS was calculated for each region and the relationship with population density tested by linear regression, thereby controlling for the underlying population structure. We found that population density in region of residence at diagnosis explained 25% of the variance in ALS rates (r = 0.5, p < 0.01). Thus, in this cohort in the south-east of England, people with ALS were more likely to be resident in areas of high population density at diagnosis. PMID:20429684

Human population, urban settlement patterns and their impact on Plasmodium falciparum malaria endemicity.

PubMed

Tatem, Andrew J; Guerra, Carlos A; Kabaria, Caroline W; Noor, Abdisalan M; Hay, Simon I

2008-10-27

The efficient allocation of financial resources for malaria control and the optimal distribution of appropriate interventions require accurate information on the geographic distribution of malaria risk and of the human populations it affects. Low population densities in rural areas and high population densities in urban areas can influence malaria transmission substantially. Here, the Malaria Atlas Project (MAP) global database of Plasmodium falciparum parasite rate (PfPR) surveys, medical intelligence and contemporary population surfaces are utilized to explore these relationships and other issues involved in combining malaria risk maps with those of human population distribution in order to define populations at risk more accurately. First, an existing population surface was examined to determine if it was sufficiently detailed to be used reliably as a mask to identify areas of very low and very high population density as malaria free regions. Second, the potential of international travel and health guidelines (ITHGs) for identifying malaria free cities was examined. Third, the differences in PfPR values between surveys conducted in author-defined rural and urban areas were examined. Fourth, the ability of various global urban extent maps to reliably discriminate these author-based classifications of urban and rural in the PfPR database was investigated. Finally, the urban map that most accurately replicated the author-based classifications was analysed to examine the effects of urban classifications on PfPR values across the entire MAP database. Masks of zero population density excluded many non-zero PfPR surveys, indicating that the population surface was not detailed enough to define areas of zero transmission resulting from low population densities. In contrast, the ITHGs enabled the identification and mapping of 53 malaria free urban areas within endemic countries. Comparison of PfPR survey results showed significant differences between author-defined 'urban' and 'rural' designations in Africa, but not for the remainder of the malaria endemic world. The Global Rural Urban Mapping Project (GRUMP) urban extent mask proved most accurate for mapping these author-defined rural and urban locations, and further sub-divisions of urban extents into urban and peri-urban classes enabled the effects of high population densities on malaria transmission to be mapped and quantified. The availability of detailed, contemporary census and urban extent data for the construction of coherent and accurate global spatial population databases is often poor. These known sources of uncertainty in population surfaces and urban maps have the potential to be incorporated into future malaria burden estimates. Currently, insufficient spatial information exists globally to identify areas accurately where population density is low enough to impact upon transmission. Medical intelligence does however exist to reliably identify malaria free cities. Moreover, in Africa, urban areas that have a significant effect on malaria transmission can be mapped.

Evidence of a High Density Population of Harvested Leopards in a Montane Environment

PubMed Central

Chase Grey, Julia N.; Kent, Vivien T.; Hill, Russell A.

2013-01-01

Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus) population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR) analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications. PMID:24349375

Effects of urban sprawl on obesity.

PubMed

Zhao, Zhenxiang; Kaestner, Robert

2010-12-01

In this paper, we examine the effect of changes in population density-urban sprawl-between 1970 and 2000 on BMI and obesity of residents in metropolitan areas in the U.S. We address the possible endogeneity of population density by using a two-step instrumental variables approach. We exploit the plausibly exogenous variation in population density caused by the expansion of the U.S. Interstate Highway System, which largely followed the original 1947 plan for the Interstate Highway System. We find a negative association between population density and obesity, and estimates are robust across a wide range of specifications. Estimates indicate that if the average metropolitan area had not experienced the decline in the proportion of population living in dense areas over the last 30 years, the rate of obesity would have been reduced by approximately 13%. Copyright © 2010 Elsevier B.V. All rights reserved.

Association between population density and reported incidence, characteristics and outcome after out-of-hospital cardiac arrest in Sweden.

PubMed

Strömsöe, A; Svensson, L; Claesson, A; Lindkvist, J; Lundström, A; Herlitz, J

2011-10-01

To describe the reported incidence of out of hospital cardiac arrest (OHCA) and the characteristics and outcome after OHCA in relation to population density in Sweden. All patients participating in the Swedish Cardiac Arrest Register between 2008 and 2009 in (a) 20 of 21 regions (n=6457) and in (b) 165 of 292 municipalities (n=3522) in Sweden, took part in the survey. The regional population density varied between 3 and 310 inhabitants per km(2) in 2009. In 2008-2009, the number of reported cardiac arrests varied between 13 and 52 per 100,000 inhabitants and year. Survival to 1 month varied between 2% and 14% during the same period in different regions. With regard to population density, based on municipalities, bystander CPR (p=0.04) as well as cardiac etiology (p=0.002) were more frequent in less populated areas. Ambulance response time was longer in less populated areas (p<0.0001). There was no significant association between population density and survival to 1 month after OHCA or incidence (adjusted for age and gender) of OHCA. There was no significant association between population density and survival to 1 month after OHCA or incidence (adjusted for age and gender) of OHCA. However, bystander CPR, cardiac etiology and longer response times were more frequent in less populated areas. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Is ethnic density associated with risk of child pedestrian injury? A comparison of inter-census changes in ethnic populations and injury rates.

PubMed

Steinbach, Rebecca; Green, Judith; Kenward, Michael G; Edwards, Phil

2016-01-01

Research on inequalities in child pedestrian injury risk has identified some puzzling trends: although, in general, living in more affluent areas protects children from injury, this is not true for those in some minority ethnic groups. This study aimed to identify whether 'group density' effects are associated with injury risk, and whether taking these into account alters the relationship between area deprivation and injury risk. 'Group density' effects exist when ethnic minorities living in an area with a higher proportion of people from a similar ethnic group enjoy better health than those who live in areas with a lower proportion, even though areas with dense minority ethnic populations can be relatively more materially disadvantaged. This study utilised variation in minority ethnic densities in London between two census periods to identify any associations between group density and injury risk. Using police data on road traffic injury and population census data from 2001 to 2011, the numbers of 'White,' 'Asian' and 'Black' child pedestrian injuries in an area were modelled as a function of the percentage of the population in that area that are 'White,' 'Asian' and 'Black,' controlling for socio-economic disadvantage and characteristics of the road environment. There was strong evidence (p < 0.001) of a negative association between 'Black' population density and 'Black' child pedestrian injury risk [incidence (of injury) rate ratios (IRR) 0.575, 95% CI 0.515-0.642]. There was weak evidence (p = 0.083) of a negative association between 'Asian' density and 'Asian' child pedestrian injury risk (IRR 0.901, 95% CI 0.801-1.014) and no evidence (p = 0.412) of an association between 'White' density and 'White' child pedestrian injury risk (IRR 1.075, 95% CI 0.904-1.279). When group density effects are taken into account, area deprivation is associated with injury risk of all ethnic groups. Group density appears to protect 'Black' children living in London against pedestrian injury risk. These findings suggest that future research should focus on structural properties of societies to explain the relationships between minority ethnicity and risk.

The relationship between male moth density and female mating success in invading populations of Lymantria dispar

Treesearch

Patrick C. Tobin; Ksenia S. Onufrieva; Kevin W. Thorpe

2012-01-01

The successful establishment of non-native species in new areas can be affected by many factors including the initial size of the founder population. Populations comprised of fewer individuals tend to be subject to stochastic forces and Allee effects (positive-density dependence), which can challenge the ability of small founder populations to establish in a new area....

Exploring the relationship between population density and maternal health coverage.

PubMed

Hanlon, Michael; Burstein, Roy; Masters, Samuel H; Zhang, Raymond

2012-11-21

Delivering health services to dense populations is more practical than to dispersed populations, other factors constant. This engenders the hypothesis that population density positively affects coverage rates of health services. This hypothesis has been tested indirectly for some services at a local level, but not at a national level. We use cross-sectional data to conduct cross-country, OLS regressions at the national level to estimate the relationship between population density and maternal health coverage. We separately estimate the effect of two measures of density on three population-level coverage rates (6 tests in total). Our coverage indicators are the fraction of the maternal population completing four antenatal care visits and the utilization rates of both skilled birth attendants and in-facility delivery. The first density metric we use is the percentage of a population living in an urban area. The second metric, which we denote as a density score, is a relative ranking of countries by population density. The score's calculation discounts a nation's uninhabited territory under the assumption those areas are irrelevant to service delivery. We find significantly positive relationships between our maternal health indicators and density measures. On average, a one-unit increase in our density score is equivalent to a 0.2% increase in coverage rates. Countries with dispersed populations face higher burdens to achieve multinational coverage targets such as the United Nations' Millennial Development Goals.

Population Density, Poor Sanitation, and Enteric Infections in Nueva Santa Rosa, Guatemala.

PubMed

Jarquin, Claudia; Arnold, Benjamin F; Muñoz, Fredy; Lopez, Beatriz; Cuéllar, Victoria M; Thornton, Andrew; Patel, Jaymin; Reyes, Lisette; Roy, Sharon L; Bryan, Joe P; McCracken, John P; Colford, John M

2016-04-01

Poor sanitation could pose greater risk for enteric pathogen transmission at higher human population densities because of greater potential for pathogens to infect new hosts through environmentally mediated and person-to-person transmission. We hypothesized that incidence and prevalence of diarrhea, enteric protozoans, and soil-transmitted helminth infections would be higher in high-population-density areas compared with low-population-density areas, and that poor sanitation would pose greater risk for these enteric infections at high density compared with low density. We tested our hypotheses using 6 years of clinic-based diarrhea surveillance (2007-2013) including 4,360 geolocated diarrhea cases tested for 13 pathogens and a 2010 cross-sectional survey that measured environmental exposures from 204 households (920 people) and tested 701 stool specimens for enteric parasites. We found that population density was not a key determinant of enteric infection nor a strong effect modifier of risk posed by poor household sanitation in this setting. © The American Society of Tropical Medicine and Hygiene.

Population Density, Poor Sanitation, and Enteric Infections in Nueva Santa Rosa, Guatemala

PubMed Central

Jarquin, Claudia; Arnold, Benjamin F.; Muñoz, Fredy; Lopez, Beatriz; Cuéllar, Victoria M.; Thornton, Andrew; Patel, Jaymin; Reyes, Lisette; Roy, Sharon L.; Bryan, Joe P.; McCracken, John P.; Colford, John M.

2016-01-01

Poor sanitation could pose greater risk for enteric pathogen transmission at higher human population densities because of greater potential for pathogens to infect new hosts through environmentally mediated and person-to-person transmission. We hypothesized that incidence and prevalence of diarrhea, enteric protozoans, and soil-transmitted helminth infections would be higher in high-population-density areas compared with low-population-density areas, and that poor sanitation would pose greater risk for these enteric infections at high density compared with low density. We tested our hypotheses using 6 years of clinic-based diarrhea surveillance (2007–2013) including 4,360 geolocated diarrhea cases tested for 13 pathogens and a 2010 cross-sectional survey that measured environmental exposures from 204 households (920 people) and tested 701 stool specimens for enteric parasites. We found that population density was not a key determinant of enteric infection nor a strong effect modifier of risk posed by poor household sanitation in this setting. PMID:26856919

Exploring the relationship between population density and maternal health coverage

PubMed Central

2012-01-01

Background Delivering health services to dense populations is more practical than to dispersed populations, other factors constant. This engenders the hypothesis that population density positively affects coverage rates of health services. This hypothesis has been tested indirectly for some services at a local level, but not at a national level. Methods We use cross-sectional data to conduct cross-country, OLS regressions at the national level to estimate the relationship between population density and maternal health coverage. We separately estimate the effect of two measures of density on three population-level coverage rates (6 tests in total). Our coverage indicators are the fraction of the maternal population completing four antenatal care visits and the utilization rates of both skilled birth attendants and in-facility delivery. The first density metric we use is the percentage of a population living in an urban area. The second metric, which we denote as a density score, is a relative ranking of countries by population density. The score’s calculation discounts a nation’s uninhabited territory under the assumption those areas are irrelevant to service delivery. Results We find significantly positive relationships between our maternal health indicators and density measures. On average, a one-unit increase in our density score is equivalent to a 0.2% increase in coverage rates. Conclusions Countries with dispersed populations face higher burdens to achieve multinational coverage targets such as the United Nations’ Millennial Development Goals. PMID:23170895

Outside and inside noise exposure in urban and suburban areas

Treesearch

Dwight E. Bishop; Myles A. Simpson

1977-01-01

In urban and suburban areas of the United States (away from major airports), the outdoor noise environment usually depends strongly on local vehicular traffic. By relating traffic flow to population density, a model of outdoor noise exposure has been developed for estimating the cumulative 24-hour noise exposure based upon the population density of the area. This noise...

Spatial distribution of U.S. household carbon footprints reveals suburbanization undermines greenhouse gas benefits of urban population density.

PubMed

Jones, Christopher; Kammen, Daniel M

2014-01-21

Which municipalities and locations within the United States contribute the most to household greenhouse gas emissions, and what is the effect of population density and suburbanization on emissions? Using national household surveys, we developed econometric models of demand for energy, transportation, food, goods, and services that were used to derive average household carbon footprints (HCF) for U.S. zip codes, cities, counties, and metropolitan areas. We find consistently lower HCF in urban core cities (∼ 40 tCO2e) and higher carbon footprints in outlying suburbs (∼ 50 tCO2e), with a range from ∼ 25 to >80 tCO2e in the 50 largest metropolitan areas. Population density exhibits a weak but positive correlation with HCF until a density threshold is met, after which range, mean, and standard deviation of HCF decline. While population density contributes to relatively low HCF in the central cities of large metropolitan areas, the more extensive suburbanization in these regions contributes to an overall net increase in HCF compared to smaller metropolitan areas. Suburbs alone account for ∼ 50% of total U.S. HCF. Differences in the size, composition, and location of household carbon footprints suggest the need for tailoring of greenhouse gas mitigation efforts to different populations.

Correlates of Harlequin Duck densities during winter in Prince William Sound, Alaska

USGS Publications Warehouse

Esler, Daniel N.; Bowman, Timothy D.; Dean, T.A.; O'Clair, Charles E.; Jewett, S.C.; McDonald, L.L.

2000-01-01

We evaluated relationships of Harlequin Duck (Histrionicus histrionicus) densities to habitat attributes, history of habitat contamination by the 1989 Exxon Valdez oil spill, and prey biomass density and abundance during winters 1995-1997 in Prince William Sound, Alaska. Habitat features that explained variation in duck densities included distance to streams and reefs, degree of exposure to wind and wave action, and dominant substrate type. After accounting for these effects, densities were lower in oiled than unoiled areas, suggesting that population recovery from the oil spill was not complete, due either to lack of recovery from initial oil spill effects or continuing deleterious effects. Prey biomass density and abundance were not strongly related to duck densities after accounting for habitat and area effects. Traits of Harlequin Ducks that reflect their affiliation with naturally predictable winter habitats, such as strong site fidelity and intolerance of increased energy costs, may make their populations particularly vulnerable to chronic oil spill effects and slow to recover from population reductions, which may explain lower densities than expected on oiled areas nearly a decade following the oil spill.

Predicting Grizzly Bear Density in Western North America

PubMed Central

Mowat, Garth; Heard, Douglas C.; Schwarz, Carl J.

2013-01-01

Conservation of grizzly bears (Ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend. PMID:24367552

Predicting grizzly bear density in western North America.

PubMed

Mowat, Garth; Heard, Douglas C; Schwarz, Carl J

2013-01-01

Conservation of grizzly bears (Ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. Many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. Current methods of predicting density in areas of management interest are subjective and untested. Objective methods have been proposed, but these statistical models are so dependent on results from individual study areas that the models do not generalize well. We built regression models to relate grizzly bear density to ultimate measures of ecosystem productivity and mortality for interior and coastal ecosystems in North America. We used 90 measures of grizzly bear density in interior ecosystems, of which 14 were currently known to be unoccupied by grizzly bears. In coastal areas, we used 17 measures of density including 2 unoccupied areas. Our best model for coastal areas included a negative relationship with tree cover and positive relationships with the proportion of salmon in the diet and topographic ruggedness, which was correlated with precipitation. Our best interior model included 3 variables that indexed terrestrial productivity, 1 describing vegetation cover, 2 indices of human use of the landscape and, an index of topographic ruggedness. We used our models to predict current population sizes across Canada and present these as alternatives to current population estimates. Our models predict fewer grizzly bears in British Columbia but more bears in Canada than in the latest status review. These predictions can be used to assess population status, set limits for total human-caused mortality, and for conservation planning, but because our predictions are static, they cannot be used to assess population trend.

[On the rational distribution of Chinese population].

PubMed

Zhu, Z

1980-01-01

In 1949, the population distribution in China was characterized by the following distinct features. First, it was unbalanced, with high density in the eastern regions, in the plains, and in areas adjacent to railroads, river navigation routes and other transportation axes. Low population density was found in the western regions, mountainous regions, and areas far from transportation routes. Second, Hans were largest in number and distributed throughout the country, with major concentration in the eastern regions, while the minorities constituted about 10% of the total population and were distributed mainly in the far southwestern and northwestern areas. Third, over 89% of the 540 million of the population was distributed in rural areas while only about 10% in towns and cities, with high densities in some coastal cities. During the past 3 decades, the unbalanced nature of China's population has remained basically unchanged. This can be attributed to factors relating to natural conditions and resources, productivities, socioeconomic conditions, and technological development in different regions. In order to achieve a rational distribution of the Chinese population the following measures should be taken: 1) controlling the birth rate of the Hans and increasing the population of minorities; 2) moving the population of the dense areas to the border provinces in the western regions to develop their natural resources and to elevate the living standards; 3) modernizing the rural areas; 4) strictly controlling the industrial developments of large cities and their population growth; and 5) strictly restricting the unplanned migration of population to and from cities.

Population Density Modeling for Diverse Land Use Classes: Creating a National Dasymetric Worker Population Model

NASA Astrophysics Data System (ADS)

Trombley, N.; Weber, E.; Moehl, J.

2017-12-01

Many studies invoke dasymetric mapping to make more accurate depictions of population distribution by spatially restricting populations to inhabited/inhabitable portions of observational units (e.g., census blocks) and/or by varying population density among different land classes. LandScan USA uses this approach by restricting particular population components (such as residents or workers) to building area detected from remotely sensed imagery, but also goes a step further by classifying each cell of building area in accordance with ancillary land use information from national parcel data (CoreLogic, Inc.'s ParcelPoint database). Modeling population density according to land use is critical. For instance, office buildings would have a higher density of workers than warehouses even though the latter would likely have more cells of detection. This paper presents a modeling approach by which different land uses are assigned different densities to more accurately distribute populations within them. For parts of the country where the parcel data is insufficient, an alternate methodology is developed that uses National Land Cover Database (NLCD) data to define the land use type of building detection. Furthermore, LiDAR data is incorporated for many of the largest cities across the US, allowing the independent variables to be updated from two-dimensional building detection area to total building floor space. In the end, four different regression models are created to explain the effect of different land uses on worker distribution: A two-dimensional model using land use types from the parcel data A three-dimensional model using land use types from the parcel data A two-dimensional model using land use types from the NLCD data, and A three-dimensional model using land use types from the NLCD data. By and large, the resultant coefficients followed intuition, but importantly allow the relationships between different land uses to be quantified. For instance, in the model using two-dimensional building area, commercial building area had a density 2.5 times greater than public building area and 4 times greater than industrial building area. These coefficients can be applied to define the ratios at which population is distributed to building cells. Finally, possible avenues for refining the methodology are presented.

The landscape configuration of zoonotic transmission of Ebola virus disease in West and Central Africa: interaction between population density and vegetation cover.

PubMed

Walsh, Michael G; Haseeb, Ma

2015-01-01

Ebola virus disease (EVD) is an emerging infectious disease of zoonotic origin that has been responsible for high mortality and significant social disruption in West and Central Africa. Zoonotic transmission of EVD requires contact between susceptible human hosts and the reservoir species for Ebolaviruses, which are believed to be fruit bats. Nevertheless, features of the landscape that may facilitate such points of contact have not yet been adequately identified. Nor have spatial dependencies between zoonotic EVD transmission and landscape structures been delineated. This investigation sought to describe the spatial relationship between zoonotic EVD transmission events, or spillovers, and population density and vegetation cover. An inhomogeneous Poisson process model was fitted to all precisely geolocated zoonotic transmissions of EVD in West and Central Africa. Population density was strongly associated with spillover; however, there was significant interaction between population density and green vegetation cover. In areas of very low population density, increasing vegetation cover was associated with a decrease in risk of zoonotic transmission, but as population density increased in a given area, increasing vegetation cover was associated with increased risk of zoonotic transmission. This study showed that the spatial dependencies of Ebolavirus spillover were associated with the distribution of population density and vegetation cover in the landscape, even after controlling for climate and altitude. While this is an observational study, and thus precludes direct causal inference, the findings do highlight areas that may be at risk for zoonotic EVD transmission based on the spatial configuration of important features of the landscape.

Simulated effect of pig-population density on epidemic size and choice of control strategy for classical swine fever epidemics in The Netherlands.

PubMed

Mangen, M-J J; Nielen, M; Burrell, A M

2002-12-18

We examined the importance of pig-population density in the area of an outbreak of classical swine fever (CSF) for the spread of the infection and the choice of control measures. A spatial, stochastic, dynamic epidemiological simulation model linked to a sector-level market-and-trade model for The Netherlands were used. Outbreaks in sparsely and densely populated areas were compared under four different control strategies and with two alternative trade assumptions. The obligatory control strategy required by current EU legislation was predicted to be enough to eradicate an epidemic starting in an area with sparse pig population. By contrast, additional control measures would be necessary if the outbreak began in an area with high pig density. The economic consequences of using preventive slaughter rather than emergency vaccination as an additional control measure depended strongly on the reactions of trading partners. Reducing the number of animal movements significantly reduced the size and length of epidemics in areas with high pig density. The phenomenon of carrier piglets was included in the model with realistic probabilities of infection by this route, but it made a negligible contribution to the spread of the infection.

Living on the edge: Space use of Eurasian red squirrels in marginal high-elevation habitat

NASA Astrophysics Data System (ADS)

Romeo, Claudia; Wauters, Lucas A.; Preatoni, Damiano; Tosi, Guido; Martinoli, Adriano

2010-11-01

In marginal habitats located at the edge of a species' range, environmental conditions are frequently extreme and individuals may be subject to different selective pressures compared to central populations. These so-called edge or marginal populations tend to have lower densities and reproductive rates than populations located in more suitable habitats, but little is known about local adaptations in spacing behavior. We studied space use and social organization in a population of Eurasian red squirrels ( Sciurus vulgaris) in a high-elevation marginal habitat of dwarf mountain pine ( Pinus mugo) and compared it with spacing patterns in high-quality Scots pine ( Pinus sylvestris) forest at lower-elevation. Home ranges and core areas were larger in the marginal habitat. In both habitats, males used larger home ranges than females, but sex differences in core area size were significant only in the edge population. Patterns of core area overlap were similar in both habitats with intra-sexual territoriality among adult females and higher degrees of inter-sexual overlap, typical for the species throughout its range. However, low densities in the edge population resulted in higher female by males overlap in spring-summer, suggesting males increased home ranges and core areas during mating season to augment access to estrus females. Thus, in the marginal habitat, with low food abundance and low population densities, linked with extreme winter conditions, squirrels, especially males, used large home ranges. Finally, squirrels responded more strongly to variation in food availability (inverse relation between home range size and seed abundance), and even to fluctuations in density (inverse relation between core area size and density of animals of the same sex), in the marginal than in the high-quality habitat, suggesting high behavioral plasticity to respond to the ecological constraints in marginal habitats.

Survival After HIV Infection Stage 3 (AIDS) Diagnosis, by Population Density Areas, United States, 2005-2010.

PubMed

Bosh, Karin A; Shi, Jing; Chen, Mi

We examined the survival rates after diagnosis of HIV infection stage 3 (AIDS) in the United States by population density area of residence at diagnosis. We used data from the National HIV Surveillance System to calculate survival rates among people aged ≥13 with HIV infection stage 3 (AIDS) diagnosed from 2005 through 2010. We determined survival rates for more than 12, 24, and 36 months after diagnosis; overall and by demographic characteristics; and across 3 population density area categories (large metropolitan statistical areas [MSAs, ≥500 000 people], small-to-medium MSAs [50 000 to 499 999 people], and nonmetropolitan areas [<50 000 people]). The survival rates for more than 12, 24, and 36 months after diagnosis were highest among people residing in large MSAs (90.2%, 87.2%, and 84.9%, respectively) and lowest among people residing in nonmetropolitan areas (87.3%, 84.1%, and 81.4%, respectively). With a few exceptions, survival rates were lower in those residing in nonmetropolitan areas than those residing in large MSAs and small-to-medium MSAs across most subgroups by age at diagnosis, race/ethnicity, sex, transmission category, region of residence, and year of diagnosis. Between 2005 and 2010, significant year-to-year increases occurred in the proportion of people surviving more than 36 months after diagnosis across all 3 population density area categories (estimated annual percentage change: large MSAs [0.88; 95% confidence interval (CI), 0.56-1.20]; small-to-medium MSAs [0.94; 95% CI, 0.06-1.83]; and nonmetropolitan areas [1.26; 95% CI, 0.07-2.46]). Although survival rates for those with HIV infection stage 3 (AIDS) improved in all 3 population density area categories, efforts to remove barriers to care and promote treatment adherence in nonmetropolitan areas will be necessary to eliminate survival disparities.

Peromyscus ranges at high and low population densities

USGS Publications Warehouse

Stickel, L.F.

1960-01-01

Live-trapping studies at the Patuxent Wildlife Research Center, Maryland, showed that the ranges of wood mice were larger when the population density was lower and smaller when the population density was higher. When the population density was about 1.3 male mice per acre in June 1954, the average distance recorded between traps after four or more captures was 258 feet. When the population density was about 4.1 male mice per acre in June 1957, the average distance was 119 feet. Differences were statistically significant. Females were so scarce at the low that comparisons could not be made for them. Examples from the literature also show that home range of a species may vary with population density. Other examples show that the range may vary with habitat, breeding condition and food supply. These variations in range size reduce the reliability of censuses in which relative methods are used: Lines of traps sample the population of a larger area when ranges are large than they do when ranges are small. Direct comparisons therefore will err in some degree. Error may be introduced also when line-trap data are transformed to per acre figures on the basis of home-range estimates made by area-trapping at another place or time. Variation in range size also can make it necessary to change area-trapping plans, for larger quadrants are needed when ranges are larger. It my be necessary to set traps closer together when ranges are small than when ranges are large.

Estimating large carnivore populations at global scale based on spatial predictions of density and distribution – Application to the jaguar (Panthera onca)

PubMed Central

Robinson, Hugh S.; Abarca, Maria; Zeller, Katherine A.; Velasquez, Grisel; Paemelaere, Evi A. D.; Goldberg, Joshua F.; Payan, Esteban; Hoogesteijn, Rafael; Boede, Ernesto O.; Schmidt, Krzysztof; Lampo, Margarita; Viloria, Ángel L.; Carreño, Rafael; Robinson, Nathaniel; Lukacs, Paul M.; Nowak, J. Joshua; Salom-Pérez, Roberto; Castañeda, Franklin; Boron, Valeria; Quigley, Howard

2018-01-01

Broad scale population estimates of declining species are desired for conservation efforts. However, for many secretive species including large carnivores, such estimates are often difficult. Based on published density estimates obtained through camera trapping, presence/absence data, and globally available predictive variables derived from satellite imagery, we modelled density and occurrence of a large carnivore, the jaguar, across the species’ entire range. We then combined these models in a hierarchical framework to estimate the total population. Our models indicate that potential jaguar density is best predicted by measures of primary productivity, with the highest densities in the most productive tropical habitats and a clear declining gradient with distance from the equator. Jaguar distribution, in contrast, is determined by the combined effects of human impacts and environmental factors: probability of jaguar occurrence increased with forest cover, mean temperature, and annual precipitation and declined with increases in human foot print index and human density. Probability of occurrence was also significantly higher for protected areas than outside of them. We estimated the world’s jaguar population at 173,000 (95% CI: 138,000–208,000) individuals, mostly concentrated in the Amazon Basin; elsewhere, populations tend to be small and fragmented. The high number of jaguars results from the large total area still occupied (almost 9 million km2) and low human densities (< 1 person/km2) coinciding with high primary productivity in the core area of jaguar range. Our results show the importance of protected areas for jaguar persistence. We conclude that combining modelling of density and distribution can reveal ecological patterns and processes at global scales, can provide robust estimates for use in species assessments, and can guide broad-scale conservation actions. PMID:29579129

Negative density-dependent dispersal in the American black bear (Ursus americanus) revealed by noninvasive sampling and genotyping

PubMed Central

Roy, Justin; Yannic, Glenn; Côté, Steeve D; Bernatchez, Louis

2012-01-01

Although the dispersal of animals is influenced by a variety of factors, few studies have used a condition-dependent approach to assess it. The mechanisms underlying dispersal are thus poorly known in many species, especially in large mammals. We used 10 microsatellite loci to examine population density effects on sex-specific dispersal behavior in the American black bear, Ursus americanus. We tested whether dispersal increases with population density in both sexes. Fine-scale genetic structure was investigated in each of four sampling areas using Mantel tests and spatial autocorrelation analyses. Our results revealed male-biased dispersal pattern in low-density areas. As population density increased, females appeared to exhibit philopatry at smaller scales. Fine-scale genetic structure for males at higher densities may indicate reduced dispersal distances and delayed dispersal by subadults. PMID:22822432

Population control in symbiotic corals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falkowski, P.G.; Dubinsky, Z.; Muscatine, L.

1993-10-01

Stability in symbiotic association requires control of population growth between symbionts. The population density of zooxanthellae per unit surface area of most symbiotic corals is remarkably consistant. How is the population density of zooxanthellae maintained and what happens to the symbiotic association if the balance between algae and host is perturbed. The answers to these question, examined in this paper, provide a framework for understanding how the size of the component populations is controlled in symbiotic associations. The topic areas covered include the following: carbon economy in a symbiotic coral; effects of nutrient enrichment; the chemostat model of population control;more » the effects of exposure to ammonium levels. Ammonium ions and organic materials are the factors which maintain the density of zooxanthellae. 32 refs., 5 figs.« less

Population density of red langurs in Sabangau tropical peat-swamp forest, Central Kalimantan, Indonesia.

PubMed

Ehlers Smith, David A; Ehlers Smith, Yvette C

2013-08-01

Because of the large-scale destruction of Borneo's rainforests on mineral soils, tropical peat-swamp forests (TPSFs) are increasingly essential for conserving remnant biodiversity, particularly in the lowlands where the majority of habitat conversion has occurred. Consequently, effective strategies for biodiversity conservation are required, which rely on accurate population density and distribution estimates as a baseline. We sought to establish the first population density estimates of the endemic red langur (Presbytis rubicunda) in Sabangau TPSF, the largest remaining contiguous lowland forest-block on Borneo. Using Distance sampling principles, we conducted line transect surveys in two of Sabangau's three principle habitat sub-classes and calculated group density at 2.52 groups km⁻² (95% CI 1.56-4.08) in the mixed-swamp forest sub-class. Based on an average recorded group size of 6.95 individuals, population density was 17.51 ind km⁻², the second highest density recorded in this species. The accessible area of the tall-interior forest, however, was too disturbed to yield density estimates representative of the entire sub-class, and P. rubicunda was absent from the low-pole forest, likely as a result of the low availability of the species' preferred foods. This absence in 30% of Sabangau's total area indicates the importance of in situ population surveys at the habitat-specific level for accurately informing conservation strategies. We highlight the conservation value of TPSFs for P. rubicunda given the high population density and large areas remaining, and recommend 1) quantifying the response of P. rubicunda to the logging and burning of its habitats; 2) surveying degraded TPSFs for viable populations, and 3) effectively delineating TPSF sub-class boundaries from remote imagery to facilitate population estimates across the wider peat landscape, given the stark contrast in densities found across the habitat sub-classes of Sabangau. © 2013 Wiley Periodicals, Inc.

[Integration of demographic factors in the characterization of risk areas for sleeping sickness in Côte d'Ivoire].

PubMed

Fournet, F; Kone, A; Meda, A H; Traore, S; Hervouet, J P

2001-01-01

The purpose of this study was to classify the risk for transmission of African human trypanosomiasis (sleeping sickness) according to population and settlement densities in four different areas of Zoukougbeu, Cote d'Ivoire, where the exact location of cases reported since 1990 is known. Epidemiological risk indexes were calculated from entomological data obtained from three surveys and analyzed with respect to presence of patients and occupancy rate in each area. Results indicated that there was a risk of transmission near the village of Bahigbeu II where the population density is between 30 and 40 inhabitants per km2 and settlement density is 4 per km2. There was also a risk in less inhabited areas such as Ouatigbeu where the population density is less than 30 inhabitants per km2 and dwelling density less than 4 per km2. In fact, cases are regularly reported in Ouatigbeu but never in Bahigbeu II. Based on these findings, we conclude that, while land occupancy can be considered as a risk factor for sleeping sickness, other factors such as human mobility must be taken into account to characterize risk areas and predict outbreaks.

Can the source–sink hypothesis explain macrofaunal abundance patterns in the abyss? A modelling test

PubMed Central

Hardy, Sarah M.; Smith, Craig R.; Thurnherr, Andreas M.

2015-01-01

Low food availability is a major structuring force in deep-sea benthic communities, sustaining only very low densities of organisms in parts of the abyss. These low population densities may result in an Allee effect, whereby local reproductive success is inhibited, and populations are maintained by larval dispersal from bathyal slopes. This slope–abyss source–sink (SASS) hypothesis suggests that the abyssal seafloor constitutes a vast sink habitat with macrofaunal populations sustained only by an influx of larval ‘refugees' from source areas on continental slopes, where higher productivity sustains greater population densities. Abyssal macrofaunal population densities would thus be directly related to larval inputs from bathyal source populations. We evaluate three predictions derived from the SASS hypothesis: (i) slope-derived larvae can be passively transported to central abyssal regions within a single larval period, (ii) projected larval export from slopes to the abyss reproduces global patterns of macrofaunal abundance and (iii) macrofaunal abundance decreases with distance from the continental slope. We find that abyssal macrofaunal populations are unlikely to be sustained solely through influx of larvae from slope sources. Rather, local reproduction probably sustains macrofaunal populations in relatively high-productivity abyssal areas, which must also be considered as potential larval source areas for more food-poor abyssal regions. PMID:25948686

Esophageal eosinophilia is increased in rural areas with low population density: results from a national pathology database.

PubMed

Jensen, Elizabeth T; Hoffman, Kate; Shaheen, Nicholas J; Genta, Robert M; Dellon, Evan S

2014-05-01

Eosinophilic esophagitis (EoE) is an increasingly prevalent chronic disease arising from an allergy/immune-mediated process. Generally, the risk of atopic disease differs in rural and urban environments. The relationship between population density and EoE is unknown. Our aim was to assess the relationship between EoE and population density. We conducted a cross-sectional, case-control study of patients with esophageal biopsies in a US national pathology database between January 2009 and June 2012 to assess the relationship between population density and EoE. Using geographic information systems, the population density (individuals per square mile) was determined for each patient zip code. The odds of esophageal eosinophilia and EoE were estimated for each quintile of population density and adjusted for potential confounders. Sensitivity analyses were conducted with varying case definitions and to evaluate the potential for bias from endoscopy volume and patient factors. Of 292,621 unique patients in the source population, 89,754 had normal esophageal biopsies and 14,381 had esophageal eosinophilia with ≥15 eosinophils per high-power field. The odds of having esophageal eosinophilia increased with decreasing population density (P for trend <0.001). Compared with those in the highest quintile of population density, odds of having esophageal eosinophilia were significantly higher among those in the lowest quintile of population density (adjusted odds ratio (aOR) 1.27, 95% confidence interval (CI): 1.18, 1.36). A similar dose-response trend was observed across case definitions with increased odds of EoE in the lowest population density quintile (aOR 1.59, 95% CI: 1.45-1.76). Estimates were robust to sensitivity analyses. Population density is strongly and inversely associated with esophageal eosinophilia and EoE. This association is robust to varying case definitions and adjustment factors. Environmental exposures that are more prominent in rural areas may be relevant to the pathogenesis of EoE.

Esophageal eosinophilia is increased in rural areas with low population density: Results from a national pathology database

PubMed Central

Jensen, Elizabeth T.; Hoffman, Kate; Shaheen, Nicholas J.; Genta, Robert M.; Dellon, Evan S.

2015-01-01

Objectives Eosinophilic esophagitis (EoE) is an increasingly prevalent chronic disease arising from an allergy/immune-mediated process. Generally, the risk of atopic disease differs in rural and urban environments. The relationship between population density and EoE is unknown. Our aim was to assess the relationship between EoE and population density. Methods : We conducted a cross-sectional, case-control study of patients with esophageal biopsies in a U.S. national pathology database between January 2009 and June 2012 to assess the relationship between population density and EoE. Using Geographic Information Systems (GIS), the population density (individuals/mile2) was determined for each patient zip code. The odds of esophageal eosinophilia and EoE were estimated for each quintile of population density and adjusted for potential confounders. Sensitivity analyses were conducted with varying case definitions and to evaluate the potential for bias from endoscopy volume and patient factors. Results Of 292,621 unique patients in the source population, 89,754 had normal esophageal biopsies and 14,381 had esophageal eosinophilia with ≥15 eosinophils per high-power field (eos/hpf). The odds of esophageal eosinophilia increased with decreasing population density (p for trend < 0.001). Compared to those in the highest quintile of population density, odds of esophageal eosinophilia were significantly higher amongst those in the lowest quintile of population density (aOR 1.27, 95% CI: 1.18, 1.36). A similar dose-response trend was observed across case definitions with odds of EoE increased in the lowest population density quintile (aOR 1.59, 95% CI: 1.45-1.76). Estimates were robust to sensitivity analyses. Conclusions Population density is strongly and inversely associated with esophageal eosinophilia and EoE. This association is robust to varying case definitions and adjustment factors. Environmental exposures more prominent in rural areas may be relevant to the pathogenesis of EoE. PMID:24667575

Effects of population reduction on white-tailed deer home-range dynamics

USGS Publications Warehouse

Crimmins, Shawn M.; Edwards, John W.; Campbell, Tyler A; Ford, W. Mark; Keyser, Patrick D.; Miller, Brad F.; Miller, Karl V.

2015-01-01

Management strategies designed to reduce the negative impacts of overabundant Odocoileus virginianus (White-tailed Deer) populations on forest regeneration may be influenced by changes in both population density and timber harvest. However, there is conflicting evidence as to how such changes in per capita resource availability influence home-range patterns. We compared home-range patterns of 33 female White-tailed Deer from a low-density population at a site with abundant browse to patterns of a sample of >100 females prior to a 75% reduction in population density and a doubling in timber harvest area. Home-range and core-area sizes were approximately 3 times larger than were found prior to population decline and timber harvest increase, consistent with predictions related to intraspecific competition. We also observed greater site fidelity than previously exhibited, although this may be an artifact of increased home-range sizes. Our results support previous research suggesting that White-tailed Deer home-range size is inversely related to population density and is driven, in part, by intraspecific competition for resources. Relationships among population density, resource availability, and home-range patterns among female White-tailed Deer appear to be complex and context specific.

Multiple factors affect a population of Agassiz's desert tortoise (Gopherus agassizii) in the Northwestern Mojave Desert

USGS Publications Warehouse

Berry, Kristin H.; Yee, Julie L.; Coble, Ashley A.; Perry, William M.; Shields, Timothy A.

2013-01-01

Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live tortoises using topography (i.e., slope), predators (Common Raven, signs of mammalian predators), and anthropogenic impacts (distances from paved road and denuded areas, density of ordnance fragments) as covariates. Models suggest that densities of tortoise sign increased with slope and signs of mammalian predators and decreased with Common Ravens, while also varying based on interaction effects involving these predictors as well as distances from paved roads, denuded areas, and ordnance. Similarly, densities of live tortoises varied by interaction effects among distances to denuded areas and paved roads, density of ordnance fragments, and slope. Thus multiple factors predict the densities and distribution of this population.

Territoriality of feral pigs in a highly persecuted population on Fort Benning, Georgia

USGS Publications Warehouse

Sparklin, B.D.; Mitchell, M.S.; Hanson, L.B.; Jolley, D.B.; Ditchkoff, S.S.

2009-01-01

We examined home range behavior of female feral pigs (Sus scrofa) in a heavily hunted population on Fort Benning Military Reservation in west-central Georgia, USA. We used Global Positioning System location data from 24 individuals representing 18 sounders (i.e., F social groups) combined with markrecapture and camera-trap data to evaluate evidence of territorial behavior at the individual and sounder levels. Through a manipulative experiment, we examined evidence for an inverse relationship between population density and home range size that would be expected for territorial animals. Pigs from the same sounder had extensive home range overlap and did not have exclusive core areas. Sounders had nearly exclusive home ranges and had completely exclusive core areas, suggesting that female feral pigs on Fort Benning were territorial at the sounder level but not at the individual level. Lethal removal maintained stable densities of pigs in our treatment area, whereas density increased in our control area; territory size in the 2 areas was weakly and inversely related to density of pigs. Territorial behavior in feral pigs could influence population density by limiting access to reproductive space. Removal strategies that 1) match distribution of removal efforts to distribution of territories, 2) remove entire sounders instead of individuals, and 3) focus efforts where high-quality food resources strongly influence territorial behaviors may be best for long-term control of feral pigs.

Population ecology of the mallard: II. Breeding habitat conditions, size of the breeding populations, and production indices

USGS Publications Warehouse

Pospahala, Richard S.; Anderson, David R.; Henny, Charles J.

1974-01-01

This report, the second in a series on a comprehensive analysis of mallard population data, provides information on mallard breeding habitat, the size and distribution of breeding populations, and indices to production. The information in this report is primarily the result of large-scale aerial surveys conducted during May and July, 1955-73. The history of the conflict in resource utilization between agriculturalists and wildlife conservation interests in the primary waterfowl breeding grounds is reviewed. The numbers of ponds present during the breeding season and the midsummer period and the effects of precipitation and temperature on the number of ponds present are analyzed in detail. No significant cycles in precipitation were detected and it appears that precipitation is primarily influenced by substantial seasonal and random components. Annual estimates (1955-73) of the number of mallards in surveyed and unsurveyed breeding areas provided estimates of the size and geographic distribution of breeding mallards in North America. The estimated size of the mallard breeding population in North America has ranged from a high of 14.4 million in 1958 to a low of 7.1 million in 1965. Generally, the mallard breeding population began to decline after the 1958 peak until 1962, and remained below 10 million birds until 1970. The decline and subsequent low level of the mallard population between 1959 and 1969 .generally coincided with a period of poor habitat conditions on the major breeding grounds. The density of mallards was highest in the Prairie-Parkland Area with an average of nearly 19.2 birds per square mile. The proportion of the continental mallard breeding population in the Prairie-Parkland Area ranged from 30% in 1962 to a high of 600/0 in 1956. The geographic distribution of breeding mallards throughout North America was significantly related to the number of May ponds in the Prairie-Parkland Area. Estimates of midsummer habitat conditions and indices to production from the July Production Survey were studied in detail. Several indices relating to production showed marked declines from west to east in the Prairie-Parkland Area, these are: (1) density of breeding mallards (per square mile and per May pond), (2) brood density (per square mile and per July pond), (3) average brood size (all species combined), and (4) brood survival from class II to class III. An index to late nesting and renesting efforts was highest during years when midsummer water conditions were good. Production rates of many ducks breeding in North America appear to be regulated by both density-dependent and density-independent factors. Spacing of birds in the Prairie-Parkland Area appeared to be a key factor in the density-dependent regulation of the population. The spacing mechanism, in conjunction with habitat conditions, influenced some birds to overfly the primary breeding grounds into less favorable habitats to the north and northwest where the production rate may be suppressed. The production rate of waterfowl in the Prairie Parkland Area seems to be independent of density (after emigration has taken place) because the production index appears to be a linear function of the number of breeding birds in the area. Similarly, the production rate of waterfowl in northern Saskatchewan and northern Manitoba appeared to be independent of density. Production indices in these northern areas appear to be a linear function of the size of the breeding population. Thus, the density and distribution of breeding ducks is probably regulated through a spacing mechanism that is at least partially dependent on measurable environmental factors. The result is a density-dependent process operating to ultimately effect the production and production rate of breeding ducks on a continent-wide basis. Continental production, and therefore the size of the fall population, is probably partially regulated by the number of birds that are distributed north and northwest into environments less favorable for successful reproduction. Thus, spacing of the birds in the Prairie-Parkland Area and the movement of a fraction of the birds out of the prime breeding areas may be key factors in the density-dependent regulation of the total mallard population.

Use of non-invasive genetics to generate core-area population estimates of a threatened predator in the Superior National Forest, USA

USGS Publications Warehouse

Barber-Meyer, Shannon; Ryan, Daniel; Grosshuesch, David; Catton, Timothy; Malick-Wahls, Sarah

2018-01-01

core areas and averaged 52.3 (SD=8.3, range=43-59) during 2015-2017 in the larger core areas. We found no evidence for a decrease or increase in abundance during either period. Lynx density estimates were approximately 7-10 times lower than densities of lynx in northern populations at the low of the snowshoe hare (Lepus americanus) population cycle. To our knowledge, our results are the first attempt to estimate abundance, trend and density of lynx in Minnesota using non-invasive genetic capture-mark-recapture. Estimates such as ours provide useful benchmarks for future comparisons by providing a context with which to assess 1) potential changes in forest management that may affect lynx recovery and conservation, and 2) possible effects of climate change on the depth, density, and duration of annual snow cover and correspondingly, potential effects on snowshoe hares as well.

Compensatory mortality in mule deer populations: Final technical report, January 1, 1985--December 31, 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, G.C.

1989-03-01

The hypothesis of compensatory mortality is critical to understanding population dynamics of wildlife species. This knowledge is vital regardless of whether populations are managed for recreational hunting or habitats are altered via energy development projects. This research tested for compensatory mortality in the juvenile (fawn) portion of a mule deer population. Two experimental manipulations were used employing radio-collared deer. In this study, /approximately/20% of the population was moved from a treatment area and fawn survival rates compared to those on the control area. In the pasture study, deer were stocked in pastures at 3 densities of 44, 89, and 139more » deer/km/sup 2/. Lowering of density in the field portion of the study did not appear to affect fawn survival. This is attributed to not removing enough animals for existing range conditions that have been imparted by high deer densities during the last 3 decades. Also, the effect of removal was tempered by an increase in yearling males brought about by antler-point restrictions during the harvest. Deer removed from the treatment area were used to stock 3 large pastures at low, medium, and high densities of 44, 89, and 139 deer/km/sup 2/, respectively. Fawn survival was significantly different between densities (P < 0.001), with the low density pasture showing the highest survival and the high density pasture showing the lowest survival. The main cause of death was starvation suggesting that food supplies were limiting. A strong compensatory mortality process is operating in this mule deer population as evidenced by the pasture data. We did not detect this process in the field portion of the study because the removal of /approximately/20% of the population was insufficient to allow an immediate improvement in fawn nutrition. The density-dependent survival response in the controlled pasture study demonstrated that compensatory mortality is operating in this population. 57 refs., 7 figs., 6 tabs.« less

Low leopard populations in protected areas of Maputaland: a consequence of poaching, habitat condition, abundance of prey, and a top predator.

PubMed

Ramesh, Tharmalingam; Kalle, Riddhika; Rosenlund, Havard; Downs, Colleen T

2017-03-01

Identifying the primary causes affecting population densities and distribution of flagship species are necessary in developing sustainable management strategies for large carnivore conservation. We modeled drivers of spatial density of the common leopard ( Panthera pardus ) using a spatially explicit capture-recapture-Bayesian approach to understand their population dynamics in the Maputaland Conservation Unit, South Africa. We camera-trapped leopards in four protected areas (PAs) of varying sizes and disturbance levels covering 198 camera stations. Ours is the first study to explore the effects of poaching level, abundance of prey species (small, medium, and large), competitors (lion Panthera leo and spotted hyenas Crocuta crocuta ), and habitat on the spatial distribution of common leopard density. Twenty-six male and 41 female leopards were individually identified and estimated leopard density ranged from 1.6 ± 0.62/100 km 2 (smallest PA-Ndumo) to 8.4 ± 1.03/100 km 2 (largest PA-western shores). Although dry forest thickets and plantation habitats largely represented the western shores, the plantation areas had extremely low leopard density compared to native forest. We found that leopard density increased in areas when low poaching levels/no poaching was recorded in dry forest thickets and with high abundance of medium-sized prey, but decreased with increasing abundance of lion. Because local leopard populations are vulnerable to extinction, particularly in smaller PAs, the long-term sustainability of leopard populations depend on developing appropriate management strategies that consider a combination of multiple factors to maintain their optimal habitats.

High population density enhances recruitment and survival of a harvested coral reef fish.

PubMed

Wormald, Clare L; Steele, Mark A; Forrester, Graham E

2013-03-01

A negative relationship between population growth and population density (direct density dependence) is necessary for population regulation and is assumed in most models of harvested populations. Experimental tests for density dependence are lacking for large-bodied, harvested fish because of the difficulty of manipulating population density over large areas. We studied a harvested coral reef fish, Lutjanus apodus (schoolmaster snapper), using eight large, isolated natural reefs (0.4-1.6 ha) in the Bahamas as replicates. An initial observational test for density dependence was followed by a manipulation of population density. The manipulation weakened an association between density and shelter-providing habitat features and revealed a positive effect of population density on recruitment and survival (inverse density dependence), but no effect of density on somatic growth. The snappers on an individual reef were organized into a few shoals, and we hypothesize that large shoals on high-density reefs were less vulnerable to large piscivores (groupers and barracudas) than the small shoals on low-density reefs. Reductions in predation risk for individuals in large social groups are well documented, but because snapper shoals occupied reefs the size of small marine reserves, these ecological interactions may influence the outcome of management actions.

Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia.

PubMed

Cheyne, Susan M; Thompson, Claire J H; Phillips, Abigail C; Hill, Robyn M C; Limin, Suwido H

2008-01-01

We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.

Resource selection by black-footed ferrets in South Dakota and Montana

USGS Publications Warehouse

Jachowski, D.S.; Millspaugh, J.J.; Biggins, D.E.; Livieri, T.M.; Matchett, M.R.; Rittenhouse, C.D.

2011-01-01

The black-footed ferret (Mustela nigripes), once extinct in the wild, remains one of the most critically endangered mammals in North America despite 18 years of reintroduction attempts. Because black-footed ferrets are specialized predators of prairie dogs (Cynomys sp.), a better understanding of how black-footed ferrets select resources might provide insight into how best to identify and manage reintroduction sites. We monitored ferret resource selection at two reintroduction sites with different densities of prairie dog populations-one that contained a high density of prairie dogs (Conata Basin, South Dakota) and one that was lower (UL Bend, Montana). We evaluated support for hypotheses about ferret resource selection as related to the distribution of active burrows used by black-tailed prairie dogs (Cynomys ludovicianus), interactions between ferrets, and habitat edge effects. We found support for all three factors within both populations; however, they affected ferret resource selection differently at each site. Ferrets at Conata Basin tended to select areas with high prairie dog burrow density, closer to the colony edge, and that overlapped other ferret ranges. In contrast, ferrets at UL Bend tended not to select areas of high active prairie dog burrow density, avoided areas close to edge habitat, and females avoided areas occupied by other ferrets. The differences observed between the two sites might be best explained by prairie dog densities, which were higher at Conata Basin (119.3 active burrows per ha) than at UL Bend (44.4 active burrows per ha). Given the positive growth of ferret populations at Conata Basin, management that increases the density of prairie dogs might enhance ferret success within natural areas. To achieve long-term recovery of ferrets in the wild, conservationists should increasingly work across and outside natural area boundaries to increase prairie dog populations.

49 CFR 192.609 - Change in class location: Required study.

Code of Federal Regulations, 2013 CFR

2013-10-01

... in class location: Required study. Whenever an increase in population density indicates a change in... account, for the segment of pipeline involved; and (f) The actual area affected by the population density...

49 CFR 192.609 - Change in class location: Required study.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in class location: Required study. Whenever an increase in population density indicates a change in... account, for the segment of pipeline involved; and (f) The actual area affected by the population density...

Density-Dependent Regulation of Brook Trout Population Dynamics along a Core-Periphery Distribution Gradient in a Central Appalachian Watershed

PubMed Central

Huntsman, Brock M.; Petty, J. Todd

2014-01-01

Spatial population models predict strong density-dependence and relatively stable population dynamics near the core of a species' distribution with increasing variance and importance of density-independent processes operating towards the population periphery. Using a 10-year data set and an information-theoretic approach, we tested a series of candidate models considering density-dependent and density-independent controls on brook trout population dynamics across a core-periphery distribution gradient within a central Appalachian watershed. We sampled seven sub-populations with study sites ranging in drainage area from 1.3–60 km2 and long-term average densities ranging from 0.335–0.006 trout/m. Modeled response variables included per capita population growth rate of young-of-the-year, adult, and total brook trout. We also quantified a stock-recruitment relationship for the headwater population and coefficients of variability in mean trout density for all sub-populations over time. Density-dependent regulation was prevalent throughout the study area regardless of stream size. However, density-independent temperature models carried substantial weight and likely reflect the effect of year-to-year variability in water temperature on trout dispersal between cold tributaries and warm main stems. Estimated adult carrying capacities decreased exponentially with increasing stream size from 0.24 trout/m in headwaters to 0.005 trout/m in the main stem. Finally, temporal variance in brook trout population size was lowest in the high-density headwater population, tended to peak in mid-sized streams and declined slightly in the largest streams with the lowest densities. Our results provide support for the hypothesis that local density-dependent processes have a strong control on brook trout dynamics across the entire distribution gradient. However, the mechanisms of regulation likely shift from competition for limited food and space in headwater streams to competition for thermal refugia in larger main stems. It also is likely that source-sink dynamics and dispersal from small headwater habitats may partially influence brook trout population dynamics in the main stem. PMID:24618602

Epidemic spreading on dual-structure networks with mobile agents

NASA Astrophysics Data System (ADS)

Yao, Yiyang; Zhou, Yinzuo

2017-02-01

The rapid development of modern society continually transforms the social structure which leads to an increasingly distinct dual structure of higher population density in urban areas and lower density in rural areas. Such structure may induce distinctive spreading behavior of epidemics which does not happen in a single type structure. In this paper, we study the epidemic spreading of mobile agents on dual structure networks based on SIRS model. First, beyond the well known epidemic threshold for generic epidemic model that when the infection rate is below the threshold a pertinent infectious disease will die out, we find the other epidemic threshold which appears when the infection rate of a disease is relatively high. This feature of two thresholds for the SIRS model may lead to the elimination of infectious disease when social network has either high population density or low population density. Interestingly, however, we find that when a high density area is connected to a low density may cause persistent spreading of the infectious disease, even though the same disease will die out when it spreads in each single area. This phenomenon indicates the critical role of the connection between the two areas which could radically change the behavior of spreading dynamics. Our findings, therefore, provide new understanding of epidemiology pertinent to the characteristic modern social structure and have potential to develop controlling strategies accordingly.

Demographic response of black bears at Cold Lake, Alberta, to the removal of adult males

USGS Publications Warehouse

Sargeant, Glen A.; Ruff, Robert L.

2001-01-01

Previous reports described an increase in population density following the removal of 23 adult male black bears (Ursus americanus) from a 218-km2 study area near Cold Lake, Alberta (the CLSA). This finding plays a central role in continuing debates over population regulation in bears, but has recently been criticized because density estimates were based on assumptions that were not met. Moreover, subsequent discussion has been predicated on conjecture that human exploitation had minimal influence on population dynamics. Our reanalysis supports previous descriptions of trends in bear density at Cold Lake. However, survival records revealed heavier exploitation than previously suspected. An underlying assumption of previous interpretationsCthat the Cold Lake bear population was naturally regulated near carrying capacityCno longer seems reasonable. Adult males deterred bears in other sex-age groups from using the CLSA; however, we found no evidence that birth or death rates were affected. The observed increase in local density should not be construed as a density-dependent response. Abrupt changes in local density might not have occurred if males had been removed from a larger area encompassing the CLSA.

Fluctuations of population density in Bornean orangutans (Pongo pygmaeus morio) related to fruit availability in the Danum Valley, Sabah, Malaysia: a 10-year record including two mast fruitings and three other peak fruitings.

PubMed

Kanamori, Tomoko; Kuze, Noko; Bernard, Henry; Malim, Titol Peter; Kohshima, Shiro

2017-01-01

We investigated the population density of Bornean orangutans (Pongo pygmaeus morio) and fruit availability for 10 years (2005-2014), in primary lowland dipterocarp forests in the Danum Valley, Sabah, Malaysia. During the research period, two mast fruitings and three other peak fruiting events of different scales occurred in the study area. The orangutan population density, estimated every 2 months by the marked nest count method, changed between 0.3 and 4.4 ind/km 2 and the mean population density was 1.3 ind/km 2  ± SE 0.1 (n = 56). The population density increased markedly during mast and peak fruiting periods. A significant positive correlation was observed between the population density and fruit availability in the study period (Spearman, R = 0.3, P < 0.01, n = 56). During non-fruiting periods, however, no significant correlation was observed between them. These results suggest that the spatial difference in fruit availability during mast and peak fruiting periods was larger than during non-fruiting periods, and many orangutans temporarily moved to the study site from the surrounding areas seeking fruit.

Evaluating population expansion of black bears using spatial capture-recapture

USGS Publications Warehouse

Sun, Catherine C.; Fuller, Angela K.; Hare, Matthew P.; Hurst, Jeremy E.

2017-01-01

The population of American black bears (Ursus americanus) in southern New York, USA has been growing and expanding in range since the 1990s. This has motivated a need to anticipate future patterns of range expansion. We conducted a non-invasive, genetic, spatial capture-recapture (SCR) study to estimate black bear density and identify spatial patterns of population density that are potentially associated with range expansion. We collected hair samples in a 2,519-km2 study area in southern New York with barbed-wire hair snares and identified individuals and measured genetic diversity using 7 microsatellite loci and 1 sex-linked marker. We estimated a mean density of black bears in the region of 13.7 bears/100 km2, and detected a slight latitudinal gradient in density consistent with the documented range expansion. However, elevation and the amounts of forest, crop, and developed landcover types did not influence density, suggesting that bears are using a diversity of resources in this heterogeneous landscape outside their previously described distribution. These results provide the first robust baseline estimates for population density and distribution associated with different landcover types in the expanded bear range. Further, genetic diversity was comparable to that of non-expanding black bear populations in the eastern United States, and in combination with the latitudinal density gradient, suggest that the study area is not at the colonizing front of the range expansion. In addition, the diversity of landcover types used by bears in the study area implies a possible lack of constraints for further northern expansion of the black bear range. Our non-invasive, genetic, spatial capture-recapture approach has utility for studying populations of other species that may be expanding in range because SCR allows for the testing of explicit, spatial ecological hypotheses. 

Influence of population density on the concentration and speciation of metals in the soil and street dust from urban areas.

PubMed

Acosta, J A; Gabarrón, M; Faz, A; Martínez-Martínez, S; Zornoza, R; Arocena, J M

2015-09-01

Street dust and soil from high, medium and low populated cities and natural area were analysed for selected physical-chemical properties, total and chemical speciation of Zn, Pb, Cu, Cr, Cd, Co, Ni to understand the influence of human activities on metal accumulation and mobility in the environment. The pH, salinity, carbonates and organic carbon contents were similar between soil and dust from the same city. Population density increases dust/soil salinity but has no influence on metals concentrations in soils. Increases in metal concentrations with population density were observed in dusts. Cu, Zn, Pb, Cr can be mobilized more easily from dust compared to the soil. In addition, population density increase the percentage of Pb and Zn associated to reducible and carbonate phase in the dust. The behaviour of metals except Cd in soil is mainly affected by physico-chemical properties, while total metal influenced the speciation except Cr and Ni in dusts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Identifying high-risk areas for sporadic measles outbreaks: lessons from South Africa.

PubMed

Sartorius, Benn; Cohen, C; Chirwa, T; Ntshoe, G; Puren, A; Hofman, K

2013-03-01

To develop a model for identifying areas at high risk for sporadic measles outbreaks based on an analysis of factors associated with a national outbreak in South Africa between 2009 and 2011. Data on cases occurring before and during the national outbreak were obtained from the South African measles surveillance programme, and data on measles immunization and population size, from the District Health Information System. A Bayesian hierarchical Poisson model was used to investigate the association between the risk of measles in infants in a district and first-dose vaccination coverage, population density, background prevalence of human immunodeficiency virus (HIV) infection and expected failure of seroconversion. Model projections were used to identify emerging high-risk areas in 2012. A clear spatial pattern of high-risk areas was noted, with many interconnected (i.e. neighbouring) areas. An increased risk of measles outbreak was significantly associated with both the preceding build-up of a susceptible population and population density. The risk was also elevated when more than 20% of infants in a populous area had missed a first vaccine dose. The model was able to identify areas at high risk of experiencing a measles outbreak in 2012 and where additional preventive measures could be undertaken. The South African measles outbreak was associated with the build-up of a susceptible population (owing to poor vaccine coverage), high prevalence of HIV infection and high population density. The predictive model developed could be applied to other settings susceptible to sporadic outbreaks of measles and other vaccine-preventable diseases.

Predator-induced synchrony in population oscillations of coexisting small mammal species.

PubMed

Korpimäki, Erkki; Norrdahl, Kai; Huitu, Otso; Klemola, Tero

2005-01-22

Comprehensive analyses of long-term (1977-2003) small-mammal abundance data from western Finland showed that populations of Microtus voles (field voles M. agrestis and sibling voles M. rossiaemeridionalis) voles, bank (Clethrionomys glareolus) and common shrews (Sorex araneus) fluctuated synchronously in 3 year population cycles. Time-series analyses indicated that interspecific synchrony is influenced strongly by density-dependent processes. Synchrony among Microtus and bank voles appeared additionally to be influenced by density-independent processes. To test whether interspecific synchronization through density-dependent processes is caused by predation, we experimentally reduced the densities of the main predators of small mammals in four large agricultural areas, and compared small mammal abundances in these to those in four control areas (2.5-3 km(2)) through a 3 year small-mammal population cycle. Predator reduction increased densities of the main prey species, Microtus voles, in all phases of the population cycle, while bank voles, the most important alternative prey of predators, responded positively only in the low and the increase phase. Manipulation also increased the autumn densities of water voles (Arvicola terrestris) in the increase phase of the cycle. No treatment effects were detected for common shrews or mice. Our results are in accordance with the alternative prey hypothesis, by which predators successively reduce the densities of both main and alternative prey species after the peak phase of small-mammal population cycles, thus inducing a synchronous low phase.

An Evaluation of Population Density Mapping and Built up Area Estimates in Sri Lanka Using Multiple Methodologies

NASA Astrophysics Data System (ADS)

Engstrom, R.; Soundararajan, V.; Newhouse, D.

2017-12-01

In this study we examine how well multiple population density and built up estimates that utilize satellite data compare in Sri Lanka. The population relationship is examined at the Gram Niladhari (GN) level, the lowest administrative unit in Sri Lanka from the 2011 census. For this study we have two spatial domains, the whole country and a 3,500km2 sub-sample, for which we have complete high spatial resolution imagery coverage. For both the entire country and the sub-sample we examine how consistent are the existing publicly available measures of population constructed from satellite imagery at predicting population density? For just the sub-sample we examine how well do a suite of values derived from high spatial resolution satellite imagery predict population density and how does our built up area estimate compare to other publicly available estimates. Population measures were obtained from the Sri Lankan census, and were downloaded from Facebook, WorldPoP, GPW, and Landscan. Percentage built-up area at the GN level was calculated from three sources: Facebook, Global Urban Footprint (GUF), and the Global Human Settlement Layer (GHSL). For the sub-sample we have derived a variety of indicators from the high spatial resolution imagery. Using deep learning convolutional neural networks, an object oriented, and a non-overlapping block, spatial feature approach. Variables calculated include: cars, shadows (a proxy for building height), built up area, and buildings, roof types, roads, type of agriculture, NDVI, Pantex, and Histogram of Oriented Gradients (HOG) and others. Results indicate that population estimates are accurate at the higher, DS Division level but not necessarily at the GN level. Estimates from Facebook correlated well with census population (GN correlation of 0.91) but measures from GPW and WorldPop are more weakly correlated (0.64 and 0.34). Estimates of built-up area appear to be reliable. In the 32 DSD-subsample, Facebook's built- up area measure is highly correlated with our built-up measure (correlation of 0.9). Preliminary regression results based on variables selected from Lasso-regressions indicate that satellite indicators have exceptionally strong predictive power in predicting GN level population level and density with an out of sample r-squared of 0.75 and 0.72 respectively.

Neighbourhoods matter too: the association between neighbourhood socioeconomic position, population density and breast, prostate and lung cancer incidence in Denmark between 2004 and 2008.

PubMed

Meijer, Mathias; Bloomfield, Kim; Engholm, Gerda

2013-01-01

Previous studies have shown that cancer incidence is related to a number of individual factors, including socioeconomic status. The aim of this study was to refine the current knowledge about indicators associated with cancer incidence by evaluating the influence of neighbourhood characteristics on breast, prostate and lung cancer incidence in Denmark. All women aged 30-83 years were followed for breast cancer between 2004 and 2008, men between 50 and 83 years were followed for prostate cancer and both sexes between ages 50 and 83 were followed for lung cancer. Registry data obtained from Statistics Denmark included age, sex, availability of breast cancer screening, marital status, education, disposable income and occupational socioeconomic status on the individual level and population density and neighbourhood socioeconomic status (the proportion of unemployed) on the parish level. Frailty modelling with individuals on the first level and parishes on the second level was conducted. A significantly lower HR of breast cancer was found in areas with low population density (HR=0.93; CI 0.88 to 0.99), while neighbourhood unemployment had no effect. Inhabitants of lower unemployment areas had a higher risk of prostate cancer (HR=1.14; CI 1.08 to 1.21) compared with those in higher unemployment areas, whereas population density had no effect. Risk of lung cancer was lower in areas with lowest population density (HR=0.80; CI 0.74 to 0.85) and lowest in areas with lowest unemployment (HR=0.88; CI 0.84 to 0.92). In addition to individual-level factors, characteristics on the neighbourhood level also have an influence on breast, prostate and lung cancer incidence.

Savanna elephant numbers are only a quarter of their expected values

PubMed Central

Robson, Ashley S.; Trimble, Morgan J.; Purdon, Andrew; Young-Overton, Kim D.; Pimm, Stuart L.; van Aarde, Rudi J.

2017-01-01

Savannas once constituted the range of many species that human encroachment has now reduced to a fraction of their former distribution. Many survive only in protected areas. Poaching reduces the savanna elephant, even where protected, likely to the detriment of savanna ecosystems. While resources go into estimating elephant populations, an ecological benchmark by which to assess counts is lacking. Knowing how many elephants there are and how many poachers kill is important, but on their own, such data lack context. We collated savanna elephant count data from 73 protected areas across the continent estimated to hold ~50% of Africa’s elephants and extracted densities from 18 broadly stable population time series. We modeled these densities using primary productivity, water availability, and an index of poaching as predictors. We then used the model to predict stable densities given current conditions and poaching for all 73 populations. Next, to generate ecological benchmarks, we predicted such densities for a scenario of zero poaching. Where historical data are available, they corroborate or exceed benchmarks. According to recent counts, collectively, the 73 savanna elephant populations are at 75% of the size predicted based on current conditions and poaching levels. However, populations are at <25% of ecological benchmarks given a scenario of zero poaching (~967,000)—a total deficit of ~730,000 elephants. Populations in 30% of the 73 protected areas were <5% of their benchmarks, and the median current density as a percentage of ecological benchmark across protected areas was just 13%. The ecological context provided by these benchmark values, in conjunction with ongoing census projects, allow efficient targeting of conservation efforts. PMID:28414784

Air quality and urban form in U.S. urban areas: evidence from regulatory monitors.

PubMed

Clark, Lara P; Millet, Dylan B; Marshall, Julian D

2011-08-15

The layout of an urban area can impact air pollution via changes in emissions and their spatial distribution. Here, we explore relationships between air quality and urban form based on cross-sectional observations for 111 U.S. urban areas. We employ stepwise linear regression to quantify how long-term population-weighted outdoor concentrations of ozone, fine particulate matter (PM(2.5)), and other criteria pollutants measured by the U.S. Environmental Protection Agency depend on urban form, climate, transportation, city size, income, and region. Aspects of urban form evaluated here include city shape, road density, jobs-housing imbalance, population density, and population centrality. We find that population density is associated with higher population-weighted PM(2.5) concentrations (p < 0.01); population centrality is associated with lower population-weighted ozone and PM(2.5) concentrations (p < 0.01); and transit supply is associated with lower population-weighted PM(2.5) concentrations (p < 0.1). Among pollutants, interquartile range changes in urban form variables are associated with 4%-12% changes in population-weighted concentrations-amounts comparable, for example, to changes in climatic factors. Our empirical findings are consistent with prior modeling research and suggest that urban form could potentially play a modest but important role in achieving (or not achieving) long-term air quality goals.

Connectivity of Tiger (Panthera tigris) Populations in the Human-Influenced Forest Mosaic of Central India

PubMed Central

Joshi, Aditya; Vaidyanathan, Srinivas; Mondol, Samrat; Edgaonkar, Advait; Ramakrishnan, Uma

2013-01-01

Today, most wild tigers live in small, isolated Protected Areas within human dominated landscapes in the Indian subcontinent. Future survival of tigers depends on increasing local population size, as well as maintaining connectivity between populations. While significant conservation effort has been invested in increasing tiger population size, few initiatives have focused on landscape-level connectivity and on understanding the effect different landscape elements have on maintaining connectivity. We combined individual-based genetic and landscape ecology approaches to address this issue in six protected areas with varying tiger densities and separation in the Central Indian tiger landscape. We non-invasively sampled 55 tigers from different protected areas within this landscape. Maximum-likelihood and Bayesian genetic assignment tests indicate long-range tiger dispersal (on the order of 650 km) between protected areas. Further geo-spatial analyses revealed that tiger connectivity was affected by landscape elements such as human settlements, road density and host-population tiger density, but not by distance between populations. Our results elucidate the importance of landscape and habitat viability outside and between protected areas and provide a quantitative approach to test functionality of tiger corridors. We suggest future management strategies aim to minimize urban expansion between protected areas to maximize tiger connectivity. Achieving this goal in the context of ongoing urbanization and need to sustain current economic growth exerts enormous pressure on the remaining tiger habitats and emerges as a big challenge to conserve wild tigers in the Indian subcontinent. PMID:24223132

Connectivity of tiger (Panthera tigris) populations in the human-influenced forest mosaic of Central India.

PubMed

Joshi, Aditya; Vaidyanathan, Srinivas; Mondol, Samrat; Edgaonkar, Advait; Ramakrishnan, Uma

2013-01-01

Today, most wild tigers live in small, isolated Protected Areas within human dominated landscapes in the Indian subcontinent. Future survival of tigers depends on increasing local population size, as well as maintaining connectivity between populations. While significant conservation effort has been invested in increasing tiger population size, few initiatives have focused on landscape-level connectivity and on understanding the effect different landscape elements have on maintaining connectivity. We combined individual-based genetic and landscape ecology approaches to address this issue in six protected areas with varying tiger densities and separation in the Central Indian tiger landscape. We non-invasively sampled 55 tigers from different protected areas within this landscape. Maximum-likelihood and Bayesian genetic assignment tests indicate long-range tiger dispersal (on the order of 650 km) between protected areas. Further geo-spatial analyses revealed that tiger connectivity was affected by landscape elements such as human settlements, road density and host-population tiger density, but not by distance between populations. Our results elucidate the importance of landscape and habitat viability outside and between protected areas and provide a quantitative approach to test functionality of tiger corridors. We suggest future management strategies aim to minimize urban expansion between protected areas to maximize tiger connectivity. Achieving this goal in the context of ongoing urbanization and need to sustain current economic growth exerts enormous pressure on the remaining tiger habitats and emerges as a big challenge to conserve wild tigers in the Indian subcontinent.

Socio-demographic diversity and unexplained variation in death rates among the most deprived parliamentary constituencies in Britain.

PubMed

Tunstall, H; Mitchell, R; Gibbs, J; Platt, S; Dorling, D

2012-06-01

There is considerable unexplained variation in death rates between deprived areas of Britain. This analysis assesses the degree of variation in socio-demographic factors among deprivation deciles and how variables associated with deaths differ among the most deprived areas. Death rates 1996-2001, Carstairs' 2001 deprivation score and indicators, population density, black and minority ethnic group (BME) and population change 1971-2001 were calculated for 641 parliamentary constituencies in Britain. Constituencies were grouped into Carstairs' deciles. We assessed standard errors of all variables by decile and the relationship between death rates and socio-demographic variables with Pearson's correlations and linear regression by decile and for all constituencies combined. Standard errors in death rates and most socio-demographic variables were greatest for the most deprived decile. Death rates among all constituencies were positively correlated with Carstairs' score and indicators, density and BME, but for the most deprived decile, there was no association with Carstairs and a negative correlation with overcrowding, density and BME. For the most deprived decile multivariate models containing population density, BME and change had substantially higher R(2). Understanding variations in death rates between deprived areas requires greater consideration of their socio-demographic diversity including their population density, ethnicity and migration.

Effects of scale of movement, detection probability, and true population density on common methods of estimating population density

DOE PAGES

Keiter, David A.; Davis, Amy J.; Rhodes, Olin E.; ...

2017-08-25

Knowledge of population density is necessary for effective management and conservation of wildlife, yet rarely are estimators compared in their robustness to effects of ecological and observational processes, which can greatly influence accuracy and precision of density estimates. For this study, we simulate biological and observational processes using empirical data to assess effects of animal scale of movement, true population density, and probability of detection on common density estimators. We also apply common data collection and analytical techniques in the field and evaluate their ability to estimate density of a globally widespread species. We find that animal scale of movementmore » had the greatest impact on accuracy of estimators, although all estimators suffered reduced performance when detection probability was low, and we provide recommendations as to when each field and analytical technique is most appropriately employed. The large influence of scale of movement on estimator accuracy emphasizes the importance of effective post-hoc calculation of area sampled or use of methods that implicitly account for spatial variation. In particular, scale of movement impacted estimators substantially, such that area covered and spacing of detectors (e.g. cameras, traps, etc.) must reflect movement characteristics of the focal species to reduce bias in estimates of movement and thus density.« less

Effects of scale of movement, detection probability, and true population density on common methods of estimating population density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keiter, David A.; Davis, Amy J.; Rhodes, Olin E.

Knowledge of population density is necessary for effective management and conservation of wildlife, yet rarely are estimators compared in their robustness to effects of ecological and observational processes, which can greatly influence accuracy and precision of density estimates. For this study, we simulate biological and observational processes using empirical data to assess effects of animal scale of movement, true population density, and probability of detection on common density estimators. We also apply common data collection and analytical techniques in the field and evaluate their ability to estimate density of a globally widespread species. We find that animal scale of movementmore » had the greatest impact on accuracy of estimators, although all estimators suffered reduced performance when detection probability was low, and we provide recommendations as to when each field and analytical technique is most appropriately employed. The large influence of scale of movement on estimator accuracy emphasizes the importance of effective post-hoc calculation of area sampled or use of methods that implicitly account for spatial variation. In particular, scale of movement impacted estimators substantially, such that area covered and spacing of detectors (e.g. cameras, traps, etc.) must reflect movement characteristics of the focal species to reduce bias in estimates of movement and thus density.« less

Estimating Population Density of the San Martin Titi Monkey (Callicebus oenanthe) in Peru Using Vocalisations.

PubMed

van Kuijk, Silvy M; García-Suikkanen, Carolina; Tello-Alvarado, Julio C; Vermeer, Jan; Hill, Catherine M

2015-01-01

We calculated the population density of the critically endangered Callicebus oenanthe in the Ojos de Agua Conservation Concession, a dry forest area in the department of San Martin, Peru. Results showed significant differences (p < 0.01) in group densities between forest boundaries (16.5 groups/km2, IQR = 21.1-11.0) and forest interior (4.0 groups/km2, IQR = 5.0-0.0), suggesting the 2,550-ha area harbours roughly 1,150 titi monkeys. This makes Ojos de Agua an important cornerstone in the conservation of the species, because it is one of the largest protected areas where the species occurs. © 2016 S. Karger AG, Basel.

Ultrashort electromagnetic pulse control of intersubband quantum well transitions

PubMed Central

2012-01-01

We study the creation of high-efficiency controlled population transfer in intersubband transitions of semiconductor quantum wells. We give emphasis to the case of interaction of the semiconductor quantum well with electromagnetic pulses with a duration of few cycles and even a single cycle. We numerically solve the effective nonlinear Bloch equations for a specific double GaAs/AlGaAs quantum well structure, taking into account the ultrashort nature of the applied field, and show that high-efficiency population inversion is possible for specific pulse areas. The dependence of the efficiency of population transfer on the electron sheet density and the carrier envelope phase of the pulse is also explored. For electromagnetic pulses with a duration of several cycles, we find that the change in the electron sheet density leads to a very different response of the population in the two subbands to pulse area. However, for pulses with a duration equal to or shorter than 3 cycles, we show that efficient population transfer between the two subbands is possible, independent of the value of electron sheet density, if the pulse area is Π. PMID:22916956

Ultrashort electromagnetic pulse control of intersubband quantum well transitions.

PubMed

Paspalakis, Emmanuel; Boviatsis, John

2012-08-23

: We study the creation of high-efficiency controlled population transfer in intersubband transitions of semiconductor quantum wells. We give emphasis to the case of interaction of the semiconductor quantum well with electromagnetic pulses with a duration of few cycles and even a single cycle. We numerically solve the effective nonlinear Bloch equations for a specific double GaAs/AlGaAs quantum well structure, taking into account the ultrashort nature of the applied field, and show that high-efficiency population inversion is possible for specific pulse areas. The dependence of the efficiency of population transfer on the electron sheet density and the carrier envelope phase of the pulse is also explored. For electromagnetic pulses with a duration of several cycles, we find that the change in the electron sheet density leads to a very different response of the population in the two subbands to pulse area. However, for pulses with a duration equal to or shorter than 3 cycles, we show that efficient population transfer between the two subbands is possible, independent of the value of electron sheet density, if the pulse area is Π.

Growth rates and variances of unexploited wolf populations in dynamic equilibria

USGS Publications Warehouse

Mech, L. David; Fieberg, John

2015-01-01

Several states have begun harvesting gray wolves (Canis lupus), and these states and various European countries are closely monitoring their wolf populations. To provide appropriate perspective for determining unusual or extreme fluctuations in their managed wolf populations, we analyzed natural, long-term, wolf-population-density trajectories totaling 130 years of data from 3 areas: Isle Royale National Park in Lake Superior, Michigan, USA; the east-central Superior National Forest in northeastern Minnesota, USA; and Denali National Park, Alaska, USA. Ratios between minimum and maximum annual sizes for 2 mainland populations (n = 28 and 46 yr) varied from 2.5–2.8, whereas for Isle Royale (n = 56 yr), the ratio was 6.3. The interquartile range (25th percentile, 75th percentile) for annual growth rates, Nt+1/Nt, was (0.88, 1.14), (0.92, 1.11), and (0.86, 1.12) for Denali, Superior National Forest, and Isle Royale respectively. We fit a density-independent model and a Ricker model to each time series, and in both cases we considered the potential for observation error. Mean growth rates from the density-independent model were close to 0 for all 3 populations, with 95% credible intervals including 0. We view the estimated model parameters, including those describing annual variability or process variance, as providing useful summaries of the trajectories of these populations. The estimates of these natural wolf population parameters can serve as benchmarks for comparison with those of recovering wolf populations. Because our study populations were all from circumscribed areas, fluctuations in them represent fluctuations in densities (i.e., changes in numbers are not confounded by changes in occupied area as would be the case with populations expanding their range, as are wolf populations in many states).

Field testing of immunocontraception on white-tailed deer (Odocoileus virginianus) on Fire Island National Seashore, New York, USA

USGS Publications Warehouse

Naugle, R.E.; Rutberg, A.T.; Underwood, H.B.; Turner, J.W.; Liu, I.K.; Kirkpatrick, J.F.; Lasley, B.L.; Allen, W.R.; Doberska, C.

2002-01-01

Application of contraception for the control of suburban populations of white-tailed deer (Odocoileus virginianus) has been much debated, but few data are available on field applications and even fewer on population effects. Between 1993 and 1997, 74-164 individually known female deer living on Fire Island, New York, USA, were treated remotely with an initial shot of 65 microg porcine zona pellucida (PZP) in Freund's complete adjuvant followed by booster injections of 65 microg PZP in Freund's incomplete adjuvant. Starting in 1996, progressively increasing numbers of deer were treated with vaccinating/marking darts. Estimates of population density and composition, using distance sampling methods, began in 1995 in selected portions of the study area. Between 1993 and 1997, fawning rates among individually known, treated adult females decreased by 78.9% from pretreatment rates. Population density in the most heavily treated area increased by 11% per year from 1995 to March 1998 and then decreased at 23% per year to October 2000. In 1999-2000 surveys, fawns comprised 13-14% of the total population in the most heavily treated area, versus 16-33% in nearby untreated areas. These results show that PZP can be delivered effectively to sufficient deer to affect population density and composition in some environments, but that technical and logistical improvements are needed before contraception can be used widely to manage suburban deer populations.

Density-dependent intraspecific aggression regulates survival in northern Yellowstone wolves (Canis lupus).

PubMed

Cubaynes, Sarah; MacNulty, Daniel R; Stahler, Daniel R; Quimby, Kira A; Smith, Douglas W; Coulson, Tim

2014-11-01

Understanding the population dynamics of top-predators is essential to assess their impact on ecosystems and to guide their management. Key to this understanding is identifying the mechanisms regulating vital rates. Determining the influence of density on survival is necessary to understand the extent to which human-caused mortality is compensatory or additive. In wolves (Canis lupus), empirical evidence for density-dependent survival is lacking. Dispersal is considered the principal way in which wolves adjust their numbers to prey supply or compensate for human exploitation. However, studies to date have primarily focused on exploited wolf populations, in which density-dependent mechanisms are likely weak due to artificially low wolf densities. Using 13 years of data on 280 collared wolves in Yellowstone National Park, we assessed the effect of wolf density, prey abundance and population structure, as well as winter severity, on age-specific survival in two areas (prey-rich vs. prey-poor) of the national park. We further analysed cause-specific mortality and explored the factors driving intraspecific aggression in the prey-rich northern area of the park. Overall, survival rates decreased during the study. In northern Yellowstone, density dependence regulated adult survival through an increase in intraspecific aggression, independent of prey availability. In the interior of the park, adult survival was less variable and density-independent, despite reduced prey availability. There was no effect of prey population structure in northern Yellowstone, or of winter severity in either area. Survival was similar among yearlings and adults, but lower for adults older than 6 years. Our results indicate that density-dependent intraspecific aggression is a major driver of adult wolf survival in northern Yellowstone, suggesting intrinsic density-dependent mechanisms have the potential to regulate wolf populations at high ungulate densities. When low prey availability or high removal rates maintain wolves at lower densities, limited inter-pack interactions may prevent density-dependent survival, consistent with our findings in the interior of the park. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Using spatial mark-recapture for conservation monitoring of grizzly bear populations in Alberta.

PubMed

Boulanger, John; Nielsen, Scott E; Stenhouse, Gordon B

2018-03-26

One of the challenges in conservation is determining patterns and responses in population density and distribution as it relates to habitat and changes in anthropogenic activities. We applied spatially explicit capture recapture (SECR) methods, combined with density surface modelling from five grizzly bear (Ursus arctos) management areas (BMAs) in Alberta, Canada, to assess SECR methods and to explore factors influencing bear distribution. Here we used models of grizzly bear habitat and mortality risk to test local density associations using density surface modelling. Results demonstrated BMA-specific factors influenced density, as well as the effects of habitat and topography on detections and movements of bears. Estimates from SECR were similar to those from closed population models and telemetry data, but with similar or higher levels of precision. Habitat was most associated with areas of higher bear density in the north, whereas mortality risk was most associated (negatively) with density of bears in the south. Comparisons of the distribution of mortality risk and habitat revealed differences by BMA that in turn influenced local abundance of bears. Combining SECR methods with density surface modelling increases the resolution of mark-recapture methods by directly inferring the effect of spatial factors on regulating local densities of animals.

Effects of combined sewer overflow and stormwater on indicator bacteria concentrations in the Tama River due to the high population density of Tokyo Metropolitan area.

PubMed

Ham, Young-Sik; Kobori, Hiromi; Takasago, Masahisa

2009-05-01

The indicator bacteria (standard plate count, total coliform, and fecal coliform bacteria) concentrations have been investigated using six ambient habitats (population density, percent sewer penetration, stream flow rate (m(3)/sec), percent residential area, percent forest area and percent agricultural area) in the Tama River basin in Tokyo, Japan during June 2003 to January 2005. The downstream and tributary Tama River showed higher concentrations of TC and FC bacteria than the upstream waters, which exceeded an environmental quality standard for rivers and a bathing water quality criterion. It was estimated that combined sewer overflow (CSO) and stormwater effluents contributed -4-23% to the indicator bacteria concentrations of the Tama River. The results of multiple regression analyses show that the indicator bacteria concentrations of Tama River basin are significantly affected by population density. It is concluded that the Tama River received a significant bacterial contamination load originating from the anthropogenic source.

Predator-induced synchrony in population oscillations of coexisting small mammal species

PubMed Central

Korpimäki, Erkki; Norrdahl, Kai; Huitu, Otso; Klemola, Tero

2005-01-01

Comprehensive analyses of long-term (1977–2003) small-mammal abundance data from western Finland showed that populations of Microtus voles (field voles M. agrestis and sibling voles M. rossiaemeridionalis) voles, bank (Clethrionomys glareolus) and common shrews (Sorex araneus) fluctuated synchronously in 3 year population cycles. Time-series analyses indicated that interspecific synchrony is influenced strongly by density-dependent processes. Synchrony among Microtus and bank voles appeared additionally to be influenced by density-independent processes. To test whether interspecific synchronization through density-dependent processes is caused by predation, we experimentally reduced the densities of the main predators of small mammals in four large agricultural areas, and compared small mammal abundances in these to those in four control areas (2.5–3 km2) through a 3 year small-mammal population cycle. Predator reduction increased densities of the main prey species, Microtus voles, in all phases of the population cycle, while bank voles, the most important alternative prey of predators, responded positively only in the low and the increase phase. Manipulation also increased the autumn densities of water voles (Arvicola terrestris) in the increase phase of the cycle. No treatment effects were detected for common shrews or mice. Our results are in accordance with the alternative prey hypothesis, by which predators successively reduce the densities of both main and alternative prey species after the peak phase of small-mammal population cycles, thus inducing a synchronous low phase. PMID:15695211

Probabilistic prediction models for aggregate quarry siting

USGS Publications Warehouse

Robinson, G.R.; Larkins, P.M.

2007-01-01

Weights-of-evidence (WofE) and logistic regression techniques were used in a GIS framework to predict the spatial likelihood (prospectivity) of crushed-stone aggregate quarry development. The joint conditional probability models, based on geology, transportation network, and population density variables, were defined using quarry location and time of development data for the New England States, North Carolina, and South Carolina, USA. The Quarry Operation models describe the distribution of active aggregate quarries, independent of the date of opening. The New Quarry models describe the distribution of aggregate quarries when they open. Because of the small number of new quarries developed in the study areas during the last decade, independent New Quarry models have low parameter estimate reliability. The performance of parameter estimates derived for Quarry Operation models, defined by a larger number of active quarries in the study areas, were tested and evaluated to predict the spatial likelihood of new quarry development. Population density conditions at the time of new quarry development were used to modify the population density variable in the Quarry Operation models to apply to new quarry development sites. The Quarry Operation parameters derived for the New England study area, Carolina study area, and the combined New England and Carolina study areas were all similar in magnitude and relative strength. The Quarry Operation model parameters, using the modified population density variables, were found to be a good predictor of new quarry locations. Both the aggregate industry and the land management community can use the model approach to target areas for more detailed site evaluation for quarry location. The models can be revised easily to reflect actual or anticipated changes in transportation and population features. ?? International Association for Mathematical Geology 2007.

Natural re-establishment of a population of a critically endangered primate in a secondary forest: the San Martin titi monkey (Plecturocebus oenanthe) at the Pucunucho Private Conservation Area, Peru.

PubMed

Allgas, Néstor; Shanee, Sam; Shanee, Noga; Chambers, Josie; Tello-Alvarado, Julio C; Keeley, Keefe; Pinasco, Karina

2017-04-01

The San Martin titi monkey (Plecturocebus oenanthe) is endemic to a small area of northern Peru and is considered Critically Endangered on the IUCN due to massive habitat loss. Between 1994 and 2005 small scale reforestation efforts in the 23.5 ha area of Pucunucho have led to the recuperation of habitat from an area of pasture and crop lands. The first record of P. oenanthe re-establishment in the area is from 2010, although re-establishment probably began earlier. We carried out short population surveys using triangulation to monitor densities of P. oenanthe in Pucunucho in 2011, 2012 and 2016. We estimate the current population of P. oenanthe in this area at 27 individuals, giving population densities of 35 groups/km 2 and 124 individuals/km 2 . The successful regeneration of habitat and natural re-population of the area by this Critically Endangered species provides evidence of successful reforestation based conservation activities for this and potentially other primate species. Although now protected as a Private Conservation Area, Pucunucho remains threatened.

Population density, call-response interval, and survival of out-of-hospital cardiac arrest.

PubMed

Yasunaga, Hideo; Miyata, Hiroaki; Horiguchi, Hiromasa; Tanabe, Seizan; Akahane, Manabu; Ogawa, Toshio; Koike, Soichi; Imamura, Tomoaki

2011-04-14

Little is known about the effects of geographic variation on outcomes of out-of-hospital cardiac arrest (OHCA). The present study investigated the relationship between population density, time between emergency call and ambulance arrival, and survival of OHCA, using the All-Japan Utstein-style registry database, coupled with geographic information system (GIS) data. We examined data from 101,287 bystander-witnessed OHCA patients who received emergency medical services (EMS) through 4,729 ambulatory centers in Japan between 2005 and 2007. Latitudes and longitudes of each center were determined with address-match geocoding, and linked with the Population Census data using GIS. The endpoints were 1-month survival and neurologically favorable 1-month survival defined as Glasgow-Pittsburgh cerebral performance categories 1 or 2. Overall 1-month survival was 7.8%. Neurologically favorable 1-month survival was 3.6%. In very low-density (<250/km(2)) and very high-density (≥10,000/km(2)) areas, the mean call-response intervals were 9.3 and 6.2 minutes, 1-month survival rates were 5.4% and 9.1%, and neurologically favorable 1-month survival rates were 2.7% and 4.3%, respectively. After adjustment for age, sex, cause of arrest, first aid by bystander and the proportion of neighborhood elderly people ≥65 yrs, patients in very high-density areas had a significantly higher survival rate (odds ratio (OR), 1.64; 95% confidence interval (CI), 1.44 - 1.87; p < 0.001) and neurologically favorable 1-month survival rate (OR, 1.47; 95%CI, 1.22 - 1.77; p < 0.001) compared with those in very low-density areas. Living in a low-density area was associated with an independent risk of delay in ambulance response, and a low survival rate in cases of OHCA. Distribution of EMS centers according to population size may lead to inequality in health outcomes between urban and rural areas.

Population density, call-response interval, and survival of out-of-hospital cardiac arrest

PubMed Central

2011-01-01

Background Little is known about the effects of geographic variation on outcomes of out-of-hospital cardiac arrest (OHCA). The present study investigated the relationship between population density, time between emergency call and ambulance arrival, and survival of OHCA, using the All-Japan Utstein-style registry database, coupled with geographic information system (GIS) data. Methods We examined data from 101,287 bystander-witnessed OHCA patients who received emergency medical services (EMS) through 4,729 ambulatory centers in Japan between 2005 and 2007. Latitudes and longitudes of each center were determined with address-match geocoding, and linked with the Population Census data using GIS. The endpoints were 1-month survival and neurologically favorable 1-month survival defined as Glasgow-Pittsburgh cerebral performance categories 1 or 2. Results Overall 1-month survival was 7.8%. Neurologically favorable 1-month survival was 3.6%. In very low-density (<250/km2) and very high-density (≥10,000/km2) areas, the mean call-response intervals were 9.3 and 6.2 minutes, 1-month survival rates were 5.4% and 9.1%, and neurologically favorable 1-month survival rates were 2.7% and 4.3%, respectively. After adjustment for age, sex, cause of arrest, first aid by bystander and the proportion of neighborhood elderly people ≥65 yrs, patients in very high-density areas had a significantly higher survival rate (odds ratio (OR), 1.64; 95% confidence interval (CI), 1.44 - 1.87; p < 0.001) and neurologically favorable 1-month survival rate (OR, 1.47; 95%CI, 1.22 - 1.77; p < 0.001) compared with those in very low-density areas. Conclusion Living in a low-density area was associated with an independent risk of delay in ambulance response, and a low survival rate in cases of OHCA. Distribution of EMS centers according to population size may lead to inequality in health outcomes between urban and rural areas. PMID:21489299

Threatened species richness along a Himalayan elevational gradient: quantifying the influences of human population density, range size, and geometric constraints.

PubMed

Paudel, Prakash Kumar; Sipos, Jan; Brodie, Jedediah F

2018-02-07

A crucial step in conserving biodiversity is to identify the distributions of threatened species and the factors associated with species threat status. In the biodiversity hotspot of the Himalaya, very little is known about which locations harbour the highest diversity of threatened species and whether diversity of such species is related to area, mid-domain effects (MDE), range size, or human density. In this study, we assessed the drivers of variation in richness of threatened birds, mammals, reptiles, actinopterygii, and amphibians along an elevational gradient in Nepal Himalaya. Although geometric constraints (MDE), species range size, and human population density were significantly related to threatened species richness, the interaction between range size and human population density was of greater importance. Threatened species richness was positively associated with human population density and negatively associated with range size. In areas with high richness of threatened species, species ranges tend to be small. The preponderance of species at risk of extinction at low elevations in the subtropical biodiversity hotspot could be due to the double impact of smaller range sizes and higher human density.

The scaling of contact rates with population density for the infectious disease models.

PubMed

Hu, Hao; Nigmatulina, Karima; Eckhoff, Philip

2013-08-01

Contact rates and patterns among individuals in a geographic area drive transmission of directly-transmitted pathogens, making it essential to understand and estimate contacts for simulation of disease dynamics. Under the uniform mixing assumption, one of two mechanisms is typically used to describe the relation between contact rate and population density: density-dependent or frequency-dependent. Based on existing evidence of population threshold and human mobility patterns, we formulated a spatial contact model to describe the appropriate form of transmission with initial growth at low density and saturation at higher density. We show that the two mechanisms are extreme cases that do not capture real population movement across all scales. Empirical data of human and wildlife diseases indicate that a nonlinear function may work better when looking at the full spectrum of densities. This estimation can be applied to large areas with population mixing in general activities. For crowds with unusually large densities (e.g., transportation terminals, stadiums, or mass gatherings), the lack of organized social contact structure deviates the physical contacts towards a special case of the spatial contact model - the dynamics of kinetic gas molecule collision. In this case, an ideal gas model with van der Waals correction fits well; existing movement observation data and the contact rate between individuals is estimated using kinetic theory. A complete picture of contact rate scaling with population density may help clarify the definition of transmission rates in heterogeneous, large-scale spatial systems. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Determinants of pika population density vs. occupancy in the Southern Rocky Mountains.

PubMed

Erb, Liesl P; Ray, Chris; Guralnick, Robert

2014-04-01

Species distributions are responding rapidly to global change. While correlative studies of local extinction have been vital to understanding the ecological impacts of global change, more mechanistic lines of inquiry are needed for enhanced forecasting. The current study assesses whether the predictors of local extinction also explain population density for a species apparently impacted by climate change. We tested a suite of climatic and habitat metrics as predictors of American pika (Ochotona princeps) relative population density in the Southern Rocky Mountains, USA. Population density was indexed as the density of pika latrine sites. Negative binomial regression and AICc showed that the best predictors of pika latrine density were patch area followed by two measures of vegetation quality: the diversity and relative cover of forbs. In contrast with previous studies of habitat occupancy in the Southern Rockies, climatic factors were not among the top predictors of latrine density. Populations may be buffered from decline and ultimately from extirpation at sites with high-quality vegetation. Conversely, populations at highest risk for declining density and extirpation are likely to be those in sites with poor-quality vegetation.

The First Estimates of Marbled Cat Pardofelis marmorata Population Density from Bornean Primary and Selectively Logged Forest.

PubMed

Hearn, Andrew J; Ross, Joanna; Bernard, Henry; Bakar, Soffian Abu; Hunter, Luke T B; Macdonald, David W

2016-01-01

The marbled cat Pardofelis marmorata is a poorly known wild cat that has a broad distribution across much of the Indomalayan ecorealm. This felid is thought to exist at low population densities throughout its range, yet no estimates of its abundance exist, hampering assessment of its conservation status. To investigate the distribution and abundance of marbled cats we conducted intensive, felid-focused camera trap surveys of eight forest areas and two oil palm plantations in Sabah, Malaysian Borneo. Study sites were broadly representative of the range of habitat types and the gradient of anthropogenic disturbance and fragmentation present in contemporary Sabah. We recorded marbled cats from all forest study areas apart from a small, relatively isolated forest patch, although photographic detection frequency varied greatly between areas. No marbled cats were recorded within the plantations, but a single individual was recorded walking along the forest/plantation boundary. We collected sufficient numbers of marbled cat photographic captures at three study areas to permit density estimation based on spatially explicit capture-recapture analyses. Estimates of population density from the primary, lowland Danum Valley Conservation Area and primary upland, Tawau Hills Park, were 19.57 (SD: 8.36) and 7.10 (SD: 1.90) individuals per 100 km2, respectively, and the selectively logged, lowland Tabin Wildlife Reserve yielded an estimated density of 10.45 (SD: 3.38) individuals per 100 km2. The low detection frequencies recorded in our other survey sites and from published studies elsewhere in its range, and the absence of previous density estimates for this felid suggest that our density estimates may be from the higher end of their abundance spectrum. We provide recommendations for future marbled cat survey approaches.

The First Estimates of Marbled Cat Pardofelis marmorata Population Density from Bornean Primary and Selectively Logged Forest

PubMed Central

Hearn, Andrew J.; Ross, Joanna; Bernard, Henry; Bakar, Soffian Abu; Hunter, Luke T. B.; Macdonald, David W.

2016-01-01

The marbled cat Pardofelis marmorata is a poorly known wild cat that has a broad distribution across much of the Indomalayan ecorealm. This felid is thought to exist at low population densities throughout its range, yet no estimates of its abundance exist, hampering assessment of its conservation status. To investigate the distribution and abundance of marbled cats we conducted intensive, felid-focused camera trap surveys of eight forest areas and two oil palm plantations in Sabah, Malaysian Borneo. Study sites were broadly representative of the range of habitat types and the gradient of anthropogenic disturbance and fragmentation present in contemporary Sabah. We recorded marbled cats from all forest study areas apart from a small, relatively isolated forest patch, although photographic detection frequency varied greatly between areas. No marbled cats were recorded within the plantations, but a single individual was recorded walking along the forest/plantation boundary. We collected sufficient numbers of marbled cat photographic captures at three study areas to permit density estimation based on spatially explicit capture-recapture analyses. Estimates of population density from the primary, lowland Danum Valley Conservation Area and primary upland, Tawau Hills Park, were 19.57 (SD: 8.36) and 7.10 (SD: 1.90) individuals per 100 km2, respectively, and the selectively logged, lowland Tabin Wildlife Reserve yielded an estimated density of 10.45 (SD: 3.38) individuals per 100 km2. The low detection frequencies recorded in our other survey sites and from published studies elsewhere in its range, and the absence of previous density estimates for this felid suggest that our density estimates may be from the higher end of their abundance spectrum. We provide recommendations for future marbled cat survey approaches. PMID:27007219

Comparison of capture-recapture and visual count indices of prairie dog densities in black-footed ferret habitat

USGS Publications Warehouse

Fagerstone, Kathleen A.; Biggins, Dean E.

1986-01-01

Black-footed ferrets (Mustela nigripes) are dependent on prairie dogs (Cynomys spp.) for food and on their burrows for shelter and rearing young. A stable prairie dog population may therefore be the most important factor determining the survival of ferrets. A rapid method of determining prairie dog density would be useful for assessing prairie dog density in colonies currently occupied by ferrets and for selecting prairie dog colonies in other areas for ferret translocation. This study showed that visual counts can provide a rapid density estimate. Visual counts of white-tailed prairie dogs (Cynomys leucurus) were significantly correlated (r = 0.95) with mark-recapture population density estimates on two study areas near Meeteetse, Wyoming. Suggestions are given for use of visual counts.

Conservation hotspots for marine turtle nesting in the United States based on coastal development.

PubMed

Fuentes, Mariana M P B; Gredzens, Christian; Bateman, Brooke L; Boettcher, Ruth; Ceriani, Simona A; Godfrey, Matthew H; Helmers, David; Ingram, Dianne K; Kamrowski, Ruth L; Pate, Michelle; Pressey, Robert L; Radeloff, Volker C

2016-12-01

Coastal areas provide nesting habitat for marine turtles that is critical for the persistence of their populations. However, many coastal areas are highly affected by coastal development, which affects the reproductive success of marine turtles. Knowing the extent to which nesting areas are exposed to these threats is essential to guide management initiatives. This information is particularly important for coastal areas with both high nesting density and dense human development, a combination that is common in the United States. We assessed the extent to which nesting areas of the loggerhead (Caretta caretta), the green (Chelonia mydas), the Kemp's ridley (Lepidochelys kempii), and leatherback turtles (Dermochelys coriacea) in the continental United States are exposed to coastal development and identified conservation hotspots that currently have high reproductive importance and either face high exposure to coastal development (needing intervention), or have low exposure to coastal development, and are good candidates for continued and future protection. Night-time light, housing, and population density were used as proxies for coastal development and human disturbance. About 81.6% of nesting areas were exposed to housing and human population, and 97.8% were exposed to light pollution. Further, most (>65%) of the very high- and high-density nesting areas for each species/subpopulation, except for the Kemp's ridley, were exposed to coastal development. Forty-nine nesting sites were selected as conservation hotspots; of those high-density nesting sites, 49% were sites with no/low exposure to coastal development and the other 51% were exposed to high-density coastal development. Conservation strategies need to account for ~66.8% of all marine turtle nesting areas being on private land and for nesting sites being exposed to large numbers of seasonal residents. © 2016 by the Ecological Society of America.

The area level association between suicide, deprivation, social fragmentation and population density in the Republic of Ireland: a national study.

PubMed

O'Farrell, I B; Corcoran, P; Perry, I J

2016-06-01

Numerous studies have examined the ecological relationship between suicide and area level determinants such as deprivation and social fragmentation. In Ireland, there is considerable geographic variation in the rates of suicide. However, there is a dearth of Irish studies investigating the geographic variability of suicide. The Irish Central Statistics Office (CSO) provided data relating to all deaths by suicide and deaths of undetermined intent that occurred from 2009 to 2011. Negative binomial regression was used to examine the relationship between area level suicide rates and measures of deprivation, social fragmentation and population density that were taken from the 2011 National Census. Overall deprivation had the strongest independent effect on small-area rates of suicide, with the most deprived areas showing the greatest risk of suicide (risk ratio = 2.1; 95 % CI 1.70-2.52). Low population density (rurality) was associated with an increased risk suicide in males across both age groups and among females in the older 40-64-year age group. Conversely, a weak association between high population density (urbanicity) and increased suicide risk was found among females in the 15-39-year age group. Associations with social fragmentation only became apparent in the sub group analysis. Social fragmentation was associated with an elevated risk of suicide in the older 40-64 age group, with this effect being most pronounced among females. The findings of this study demonstrate marked geographical inequalities in the distribution of suicide in Ireland and highlight the importance of targeting suicide prevention resources in the most deprived areas.

Alcohol and environmental justice: the density of liquor stores and bars in urban neighborhoods in the United States.

PubMed

Romley, John A; Cohen, Deborah; Ringel, Jeanne; Sturm, Roland

2007-01-01

This study had two purposes: (1) to characterize the density of liquor stores and bars that individuals face according to race, economic status, and age in the urban United States and (2) to assess alternative measures of retailer density based on the road network and population. We used census data on business counts and sociodemographic characteristics to compute the densities facing individuals in 9,361 urban zip codes. Blacks face higher densities of liquor stores than do whites. The density of liquor stores is greater among nonwhites in lower-income areas than among whites in lower- and higher-income areas and nonwhites in higher-income areas. Nonwhite youths face higher densities of liquor stores than white youths. The density of liquor stores and bars is lower in higher-income areas, especially for nonwhites. Mismatches between alcohol demand and the supply of liquor stores within urban neighborhoods constitute an environmental injustice for minorities and lower-income persons, with potential adverse consequences for drinking behavior and other social ills. Our results for bars are sensitive to the measure of outlet density as well as population density. Although neither measure is clearly superior, a measure that accounts for roadway miles may reflect proximity to alcohol retailers and thus serve as a useful refinement to the per-capita measure. If so, alcohol policy might also focus on density per roadway mile. Further research on the existence, causes, and consequences of environmental injustice in alcohol retailing is warranted.

Population Density and Pathology: What Are the Relationships for Man?

ERIC Educational Resources Information Center

Galle, Omer R.; And Others

Evidence of high population density's serious inhibiting effects on the reproductive, aggressive, withdrawal and sexual behavior of various animals, motivated a study of human pathology in overcrowded areas. Ecological relationships in Chicago and their impact on human behavior were assessed. The number of persons per acre, Standardized Mortality…

[Relationships of bee population fluctuation and distribution with natural environment in Anhui province].

PubMed

Yu, Linsheng; Zou, Yunding; Bi, Shoudong; Wu, Houzhang; Cao, Yifeng

2006-08-01

In 2002 to approximately 2004, an investigation was made on the bee population dynamics and its relationships with the ecological environment in four ecological regions of Anhui Province. The results indicated that in the mountainous areas of south and west Anhui, there were 46 and 37 species of nectariferous plants, and the distribution density of Apis cerena cerena population was 2.01 and 1.95 colony x km(-2), respectively. In Jianghuai area and Huaibei plain, there were 17 and 12 species of nectariferous plants, which had concentrated and short flowering period and fitted for Apis mellifera Ligustica oysterring and producing, and the distribution density of Apis cerena cerena population was 0. 06 and 0. 02 colony x km(-2), respectively. Bee population fluctuation and distribution was affected by wasp predation. The breeding proportion of Apis cerena cerena to local apis population was 41.5%, 36.8%, 3.1% and 1.1%, and that of Apis mellifera Ligustica was 58.5%, 63.2%, 96.9% and 98.9% in the mountainous areas of south and west Anhui, Jianghuai area, and Huaibei plain, respectively.

Local density regulates migratory songbird reproductive success through effects on double-brooding and nest predation.

PubMed

Woodworth, Bradley K; Wheelwright, Nathaniel T; Newman, Amy E M; Norris, D Ryan

2017-08-01

Knowledge of the density-dependent processes that regulate animal populations is key to understanding, predicting, and conserving populations. In migratory birds, density-dependence is most often studied during the breeding season, yet we still lack a robust understanding of the reproductive traits through which density influences individual reproductive success. We used 27-yr of detailed, individual-level productivity data from an island-breeding population of Savannah sparrows Passerculus sandwichensis to evaluate effects of local and total annual population density on female reproductive success. Local density (number of neighbors within 50 m of a female's nest) had stronger effects on the number of young fledged than did total annual population density. Females nesting in areas of high local density were more likely to suffer nest predation and less likely to initiate and fledge a second clutch, which led to fewer young fledged in a season. Fledging fewer young subsequently decreased the likelihood of a female recruiting offspring into the breeding population in a subsequent year. Collectively, these results provide insight into the scale and reproductive mechanisms mediating density-dependent reproductive success and fitness in songbirds. © 2017 by the Ecological Society of America.

Relations between nature-based solutions of green-blue area accessibility and socio-economic-ethnic patterns in the urban Stockholm region

NASA Astrophysics Data System (ADS)

Goldenberg, Romain; Kalantari, Zahra; Destouni, Georgia

2017-04-01

More than half of the world's population lives in cities, a proportion expected to increase to two thirds by 2050 (United Nations (UN), 2015). In this study, we investigate the spatial relationships that may exist between income and/or nationality homogeneity/heterogeneity levels of urban populations and their accessibility to local green-blue areas as possible nature-based solutions for sustainable urban design. For this investigation, we consider as a concrete case study the urban region of Stockholm, Sweden, for which we compile and use available land-cover and vegetation density data (the latter in terms of Normalised Difference Vegetation Index, NDVI) in order to identify and assess the spatial distributions of various green-blue area types and aspects. We further combine this data with spatial distribution data for population density, income and nationality, as well as with road-network data for assessing population travel times to nearby green-blue areas within the region. The present study results converge with those of other recent studies in showing large socio-economic-ethnic segregation in the Stockholm region. Moreover, the present data combination and analysis also show large spatial differences in and important socio-economic-ethnic correlations with accessibility to local green areas and nearby water bodies. Specifically, population income and share of Swedish nationals are well correlated in this region, with increases in both of these variables implying greater possibility to choose where to live within the region. The living choices of richer and more homogeneous (primarily Swedish) population parts are then found to be areas with greater local vegetation density (local green areas as identified by high-resolution NDVI data) and greater area extent of nearby water bodies (blue areas). For comparison, no such correlation is found between increased income or Swedish nationality homogeneity and accessibility to nearby forest areas (overall green area extent) or built facilities for recreation and sports. The found living choice correlations point at the importance of green-blue area parts as possible nature-based solutions in urban design and planning, with potential to improve wellbeing and social sustainability for the whole urban population and not just its rich component.

[Effect of the population density on growth and regeneration in the snail Achatina fulica].

PubMed

Sidel'nikov, A P; Stepanov, I I

2000-01-01

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Increase in Population Density and Aggravation of Social and Psychological Problems in Areas with High-Rise Construction

NASA Astrophysics Data System (ADS)

Romanova, Elena

2018-03-01

High-rise apartment houses have technical and economic advantages in areas with dense population. Their placement in the central part of the city allows increasing the number of living space in the limited territory, to bring population to the place of employment and reduce pendular migration. But increase in population density leads to psychological problems: level of a stress, fatigue increases, the number of phobias grows, infectious diseases extend quicker. These problems can be solved at resettlement of inhabitants to the suburb. However such decision leads to aggravation of a transport problem and the pulsing increase in population density in the downtown and on its suburb. To solve a transport problem, it is necessary not to increase the square of the cities. Therefore in the suburbs is also used high-rise construction. But high-rise residential districts on the suburb of the city get own social problems which are capable to destroy all advantages of high-rise construction.

Effective spatial scales for evaluating environmental determinants of population density in Yakushima macaques.

PubMed

Agetsuma, Naoki; Koda, Ryosuke; Tsujino, Riyou; Agetsuma-Yanagihara, Yoshimi

2015-02-01

Population densities of wildlife species tend to be correlated with resource productivity of habitats. However, wildlife density has been greatly modified by increasing human influences. For effective conservation, we must first identify the significant factors that affect wildlife density, and then determine the extent of the areas in which the factors should be managed. Here, we propose a protocol that accomplishes these two tasks. The main threats to wildlife are thought to be habitat alteration and hunting, with increases in alien carnivores being a concern that has arisen recently. Here, we examined the effect of these anthropogenic disturbances, as well as natural factors, on the local density of Yakushima macaques (Macaca fuscata yakui). We surveyed macaque densities at 30 sites across their habitat using data from 403 automatic cameras. We quantified the effect of natural vegetation (broad-leaved forest, mixed coniferous/broad-leaved forest, etc.), altered vegetation (forestry area and agricultural land), hunting pressure, and density of feral domestic dogs (Canis familiaris). The effect of each vegetation type was analyzed at numerous spatial scales (between 150 and 3,600-m radii from the camera locations) to determine the best scale for explaining macaque density (effective spatial scale). A model-selection procedure (generalized linear mixed model) was used to detect significant factors affecting macaque density. We detected that the most effective spatial scale was 400 m in radius, a scale that corresponded to group range size of the macaques. At this scale, the amount of broad-leaved forest was selected as a positive factor, whereas mixed forest and forestry area were selected as negative factors for macaque density. This study demonstrated the importance of the simultaneous evaluation of all possible factors of wildlife population density at the appropriate spatial scale. © 2014 Wiley Periodicals, Inc.

Population Density and AIDS-Related Stigma in Large-Urban, Small-Urban, and Rural Communities of the Southeastern USA.

PubMed

Kalichman, Seth; Katner, Harold; Banas, Ellen; Kalichman, Moira

2017-07-01

AIDS stigmas delay HIV diagnosis, interfere with health care, and contribute to mental health problems among people living with HIV. While there are few studies of the geographical distribution of AIDS stigma, research suggests that AIDS stigmas are differentially experienced in rural and urban areas. We conducted computerized interviews with 696 men and women living with HIV in 113 different zip code areas that were classified as large-urban, small-urban, and rural areas in a southeast US state with high-HIV prevalence. Analyses conducted at the individual level (N = 696) accounting for clustering at the zip code level showed that internalized AIDS-related stigma (e.g., the sense of being inferior to others because of HIV) was experienced with greater magnitude in less densely populated communities. Multilevel models indicated that after adjusting for potential confounding factors, rural communities reported greater internalized AIDS-related stigma compared to large-urban areas and that small-urban areas indicated greater experiences of enacted stigma (e.g., discrimination) than large-urban areas. The associations between anticipated AIDS-related stigma (e.g., expecting discrimination) and population density at the community-level were not significant. Results suggest that people living in rural and small-urban settings experience greater AIDS-related internalized and enacted stigma than their counterparts living in large-urban centers. Research is needed to determine whether low-density population areas contribute to or are sought out by people who experienced greater AIDS-related stigma. Regardless of causal directions, interventions are needed to address AIDS-related stigma, especially among people in sparsely populated areas with limited resources.

Sink populations in carnivore management: cougar demography and immigration in a hunted population.

PubMed

Robinson, Hugh S; Wielgus, Robert B; Cooley, Hilary S; Cooley, Skye W

2008-06-01

Carnivores are widely hunted for both sport and population control, especially where they conflict with human interests. It is widely believed that sport hunting is effective in reducing carnivore populations and related human-carnivore conflicts, while maintaining viable populations. However, the way in which carnivore populations respond to harvest can vary greatly depending on their social structure, reproductive strategies, and dispersal patterns. For example, hunted cougar (Puma concolor) populations have shown a great degree of resiliency. Although hunting cougars on a broad geographic scale (> 2000 km2) has reduced densities, hunting of smaller areas (i.e., game management units, < 1000 km2), could conceivably fail because of increased immigration from adjacent source areas. We monitored a heavily hunted population from 2001 to 2006 to test for the effects of hunting at a small scale (< 1000 km2) and to gauge whether population control was achieved (lambda < or = 1.0) or if hunting losses were negated by increased immigration allowing the population to remain stable or increase (lambda > or = 1.0). The observed growth rate of 1.00 was significantly higher than our predicted survival/fecundity growth rates (using a Leslie matrix) of 0.89 (deterministic) and 0.84 (stochastic), with the difference representing an 11-16% annual immigration rate. We observed no decline in density of the total population or the adult population, but a significant decrease in the average age of independent males. We found that the male component of the population was increasing (observed male population growth rate, lambda(OM) = 1.09), masking a decrease in the female component (lambda(OF) = 0.91). Our data support the compensatory immigration sink hypothesis; cougar removal in small game management areas (< 1000 km2) increased immigration and recruitment of younger animals from adjacent areas, resulting in little or no reduction in local cougar densities and a shift in population structure toward younger animals. Hunting in high-quality habitats may create an attractive sink, leading to misinterpretation of population trends and masking population declines in the sink and surrounding source areas.

Conservation investment for rare plants in urban environments.

PubMed

Schwartz, Mark W; Smith, Lacy M; Steel, Zachary L

2013-01-01

Budgets for species conservation limit actions. Expending resources in areas of high human density is costly and generally considered less likely to succeed. Yet, coastal California contains both a large fraction of narrowly endemic at-risk plant species as well as the state's three largest metropolitan regions. Hence understanding the capacity to protect species along the highly urbanized coast is a conservation priority. We examine at-risk plant populations along California's coastline from San Diego to north of San Francisco to better understand whether there is a relationship between human population density and: i) performance of at-risk plant populations; and ii) conservation spending. Answering these questions can help focus appropriate strategic conservation investment. Rare plant performance was measured using the annualized growth rate estimate between census periods using the California Natural Diversity Database. Human density was estimated using Census Bureau statistics from the year 2000. We found strong evidence for a lack of a relationship between human population density and plant population performance in California's coastal counties. Analyzing US Endangered Species expenditure reports, we found large differences in expenditures among counties, with plants in San Diego County receiving much higher expenditures than other locations. We found a slight positive relationship between expenditures on behalf of endangered species and human density. Together these data support the argument that conservation efforts by protecting habitats within urban environments are not less likely to be successful than in rural areas. Expenditures on behalf of federally listed endangered and threatened plants do not appear to be related to proximity to human populations. Given the evidence of sufficient performance in urban environments, along with a high potential to leverage public support for nature in urban environments, expenditures in these areas appear to be an appropriate use of conservation funds.

Harmful Algae Bloom Occurrence in Urban Ponds: Relationship of Toxin Levels with Cell Density and Species Composition

EPA Science Inventory

Retention ponds constructed within urban watershed areas of high density populations are common as a result of green infrastructure applications. Several urban ponds in the Northern Kentucky area were monitored for algal community (algae and cyanobacteria) from October 2012 to Se...

[Variation pattern and its affecting factors of three-dimensional landscape in urban residential community of Shenyang].

PubMed

Zhang, Pei-Feng; Hu, Yuan-Man; Xiong, Zai-Ping; Liu, Miao

2011-02-01

Based on the 1:10000 aerial photo in 1997 and the three QuickBird images in 2002, 2005, and 2008, and by using Barista software and GIS and RS techniques, the three-dimensional information of the residential community in Tiexi District of Shenyang was extracted, and the variation pattern of the three-dimensional landscape in the district during its reconstruction in 1997-2008 and related affecting factors were analyzed with the indices, ie. road density, greening rate, average building height, building height standard deviation, building coverage rate, floor area rate, building shape coefficient, population density, and per capita GDP. The results showed that in 1997-2008, the building area for industry decreased, that for commerce and other public affairs increased, and the area for residents, education, and medical cares basically remained stable. The building number, building coverage rate, and building shape coefficient decreased, while the floor area rate, average building height, height standard deviation, road density, and greening rate increased. Within the limited space of residential community, the containing capacity of population and economic activity increased, and the environment quality also improved to some extent. The variation degree of average building height increased, but the building energy consumption decreased. Population growth and economic development had positive correlations with floor area rate, road density, and greening rate, but negative correlation with building coverage rate.

Population density and mortality among individuals in motor vehicle crashes.

PubMed

Gedeborg, Rolf; Thiblin, Ingemar; Byberg, Liisa; Melhus, Håkan; Lindbäck, Johan; Michaelsson, Karl

2010-10-01

To assess whether higher mortality rates among individuals in motor vehicle crashes in areas with low population density depend on injury type and severity or are related to the performance of emergency medical services (EMS). Prehospital and hospital deaths were studied in a population-based cohort of 41,243 motor vehicle crashes that occurred in Sweden between 1998 and 2004. The final multivariable analysis was restricted to 6884 individuals in motor vehicle crashes, to minimise the effects of confounding factors. Crude mortality rates following motor vehicle crashes were inversely related to regional population density. In regions with low population density, the unadjusted rate ratio for prehospital death was 2.2 (95% CI 1.9 to 2.5) and for hospital death 1.5 (95% CI 1.1 to 1.9), compared with a high-density population. However, after controlling for regional differences in age, gender and the type/severity of injuries among 6884 individuals in motor vehicle crashes, low population density was no longer associated with increased mortality. At 25 years of age, predicted prehospital mortality was 9% lower (95% CI 5% to 12%) in regions with low population density compared with high population density. This difference decreased with increasing age, but was still 3% lower (95% CI 0.5% to 5%) at 65 years of age. The inverse relationship between population density and mortality among individuals in motor vehicle crashes is related to pre-crash factors that influence the type and severity of injuries and not to differences in EMS.

Body mass index and overweight in relation to residence distance and population density: experience from the Northern Finland birth cohort 1966.

PubMed

Näyhä, Simo; Lankila, Tiina; Rautio, Arja; Koiranen, Markku; Tammelin, Tuija H; Taanila, Anja; Rusanen, Jarmo; Laitinen, Jaana

2013-10-08

The effect of urban sprawl on body weight in Finland is not well known. To provide more information, we examined whether body mass index (BMI) and the prevalence of overweight are associated with an individual's distance to the local community centre and population density in his/her resident area. The sample consisted of 5363 men and women, members of the Northern Finland Birth Cohort 1966 (NFBC), who filled in a postal questionnaire and attended a medical checkup in 1997, at the age of 31 years. Body mass index (BMI; kg/m(2)) and the prevalence of overweight (BMI ≥ 25.0 kg/m(2)) were regressed on each subject's road distance to the resident commune's centre and on population density in the 1 km(2) geographical grid in which he/she resided, using a generalized additive model. Adjustments were made for sex, marital status, occupational class, education, leisure-time and occupational physical activity, alcohol consumption and smoking. The mean BMI among the subjects was 24.7 kg/m(2), but it increased by increasing road distance (by 1.3 kg/m(2) from 5-10 to 20-184 km) and by decreasing population density (by 1.7 kg/m(2) from 1000-19,192 to 1-5 inhabitants/km(2)). The respective increases in overweight (overall prevalence 41%) were 13 per cent units for distance and 14 per cent units for population density. Adjusted regressions based on continuous explanatory variables showed an inverse L-shaped pattern with a mean BMI of 24.6 kg/m(2) at distances shorter than 5 km and a rise of 2.6 kg/m(2) at longer distances, and an increase of 2.5 kg/m(2) from highest to lowest population density. The associations with road distance were stronger for women than men, while the sex difference in association with population density remained indeterminate. We conclude that young adults in Northern Finland who live far away from local centres or in the most sparsely populated areas are fatter than those who live close to local centres or in densely populated areas. The likely explanations include variations in everyday physical activity in different residential environments, although causality of the associations remains to be confirmed.

Body mass index and overweight in relation to residence distance and population density: experience from the Northern Finland birth cohort 1966

PubMed Central

2013-01-01

Background The effect of urban sprawl on body weight in Finland is not well known. To provide more information, we examined whether body mass index (BMI) and the prevalence of overweight are associated with an individual’s distance to the local community centre and population density in his/her resident area. Methods The sample consisted of 5363 men and women, members of the Northern Finland Birth Cohort 1966 (NFBC), who filled in a postal questionnaire and attended a medical checkup in 1997, at the age of 31 years. Body mass index (BMI; kg/m2) and the prevalence of overweight (BMI ≥ 25.0 kg/m2) were regressed on each subject’s road distance to the resident commune’s centre and on population density in the 1 km2 geographical grid in which he/she resided, using a generalized additive model. Adjustments were made for sex, marital status, occupational class, education, leisure-time and occupational physical activity, alcohol consumption and smoking. Results The mean BMI among the subjects was 24.7 kg/m2, but it increased by increasing road distance (by 1.3 kg/m2 from 5–10 to 20–184 km) and by decreasing population density (by 1.7 kg/m2 from 1000–19,192 to 1–5 inhabitants/km2). The respective increases in overweight (overall prevalence 41%) were 13 per cent units for distance and 14 per cent units for population density. Adjusted regressions based on continuous explanatory variables showed an inverse L-shaped pattern with a mean BMI of 24.6 kg/m2 at distances shorter than 5 km and a rise of 2.6 kg/m2 at longer distances, and an increase of 2.5 kg/m2 from highest to lowest population density. The associations with road distance were stronger for women than men, while the sex difference in association with population density remained indeterminate. Conclusions We conclude that young adults in Northern Finland who live far away from local centres or in the most sparsely populated areas are fatter than those who live close to local centres or in densely populated areas. The likely explanations include variations in everyday physical activity in different residential environments, although causality of the associations remains to be confirmed. PMID:24103455

Sex differences in fingerprint ridge density in a Turkish young adult population: a sample of Baskent University.

PubMed

Oktem, Hale; Kurkcuoglu, Ayla; Pelin, Ismail Can; Yazici, Ayse Canan; Aktaş, Gulnihal; Altunay, Fikret

2015-05-01

Fingerprints are considered to be one of the most reliable methods of identification. Identification of an individual plays a vital part of any medico-legal investigations. Dermatoglyphics is a branch of science that studies epidermal ridges and ridge patterns. Epidermal ridges are polygenic characteristics that form intrauterine 10-18 weeks and considered fully developed by the sixth month of fetal growth. Fingerprints are permanent morphological characteristics and criminal detection based on fingerprints is based on the principle that no two people can have identical fingerprints. Sex determination from fingerprints has been examined in different population. In this study we aimed to study fingerprint ridge density in Turkish population sample of Baskent University students. Fingerprints were obtained from 118 women, 88 men a total of 206 students aged between 17 and 28 years old by means of simple inking method. Fingerprints from all right and left hands fingers were collected in three different area of each. The ridges on fingerprints were counted diagonally on squares measuring 5 mm × 5 mm on radial, ulnar and inferior areas. The fingerprint ridge density in radial, ulnar and inferior areas and between sexes was compared statistically Mann Whitney U test and Friedman test. The ridge density was significantly greater in women in every region studied and in all fingers when compared to men. The fingerprint ridge density in the ulnar and radial areas of the fingerprints was significantly greater than the lower area. Fingerprint ridge density can be used by medico-legal examination for sex identification. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

[Demography and nesting ecology of green iguana, Iguana iguana (Squamata: Iguanidae), in 2 exploited populations in Depresión Momposina, Colombia].

PubMed

Muñoz, Eliana M; Ortega, Angela M; Bock, Brian C; Páez, Vivian P

2003-03-01

We studied the demography and nesting ecology of two populations of Iguana iguana that face heavy exploitation and habitat modification in the Momposina Depression, Colombia. Lineal transect data was analyzed using the Fourier model to provide estimates of social group densities, which was found to differ both within and among populations (1.05-6.0 groups/ha). Mean group size and overall iguana density estimates varied between populations as well (1.5-13.7 iguanas/ha). The density estimates were far lower than those reported from more protected areas in Panama and Venezuela. Iguana densities were consistently higher in sites located along rivers (2.5 iguanas/group) than in sites along the margin of marshes, probably due to vegetational differences (1.5 iguanas/group). There was no correlation between density estimates and estimates of relative abundance (number of iguanas seen/hour/person) due to differing detectabilities of iguana groups among sites. The adult sex ratio (1:2.5 males:females) agreed well with other reports in the literature based upon observation of adult social groups, and probably results from the polygynous mating system in this species rather than a real demographic skew. Nesting in this population occurs from the end of January through March and hatching occurs between April and May. We monitored 34 nests, which suffered little vertebrate predation, perhaps due to the lack of a complete vertebrate fauna in this densely inhabited area, but nests suffered from inundation, cattle trampling, and infestation by phorid fly larvae. Clutch sizes in these populations were lower than all other published reports except for the iguana population on the highly xeric island of Curaçao, implying that adult females in our area are unusually small. We argue that this is more likely the result of the exploitation of these populations rather than an adaptive response to environmentally extreme conditions.

The land-use of Bandung, its density, overcrowded area and public facility toward a compact city

NASA Astrophysics Data System (ADS)

Paramita, B.

2016-04-01

The concept of a compact city has been introduced since 1973. It is a utopian vision largely driven by a desire to see more efficient uses of resources. In 1980s, the reconfiguration of the physical urban form of metropolitan areas was increasingly debated by both theorists and practitioners. Recently, the concept of a compact city has been more focused on developed countries in which the population tends to decrease. However, in Asia, except Japan which contains many dense cities, it has become a concept which promotes relatively high residential density with mixed land uses, though rather only in population and density. This paper addresses the land-use of Bandung that having the density over 14,000 people/km2, which has been so much potential toward a compact city. Somehow, unprepared ness of urban planning and regulation, the city seemed overwrought to serve its inhabitants. This condition is shown from the demographic condition, especially population density in Bandung based on its sub areas of the city (SWK). The stack of public facilities in a certain district has led the concentration of density and activity, which finally raising the slum and overcrowded settlement. Finally, this paper explores the implications of land use management and describes challenges faced and possible approaches, especially in land-use management strategies to be implemented in Bandung.

Modelling population distribution using remote sensing imagery and location-based data

NASA Astrophysics Data System (ADS)

Song, J.; Prishchepov, A. V.

2017-12-01

Detailed spatial distribution of population density is essential for city studies such as urban planning, environmental pollution and city emergency, even estimate pressure on the environment and human exposure and risks to health. However, most of the researches used census data as the detailed dynamic population distribution are difficult to acquire, especially in microscale research. This research describes a method using remote sensing imagery and location-based data to model population distribution at the function zone level. Firstly, urban functional zones within a city were mapped by high-resolution remote sensing images and POIs. The workflow of functional zones extraction includes five parts: (1) Urban land use classification. (2) Segmenting images in built-up area. (3) Identification of functional segments by POIs. (4) Identification of functional blocks by functional segmentation and weight coefficients. (5) Assessing accuracy by validation points. The result showed as Fig.1. Secondly, we applied ordinary least square and geographically weighted regression to assess spatial nonstationary relationship between light digital number (DN) and population density of sampling points. The two methods were employed to predict the population distribution over the research area. The R²of GWR model were in the order of 0.7 and typically showed significant variations over the region than traditional OLS model. The result showed as Fig.2.Validation with sampling points of population density demonstrated that the result predicted by the GWR model correlated well with light value. The result showed as Fig.3. Results showed: (1) Population density is not linear correlated with light brightness using global model. (2) VIIRS night-time light data could estimate population density integrating functional zones at city level. (3) GWR is a robust model to map population distribution, the adjusted R2 of corresponding GWR models were higher than the optimal OLS models, confirming that GWR models demonstrate better prediction accuracy. So this method provide detailed population density information for microscale citizen studies.

A Marriage Of Larval Modeling And Empirical Data: Linking Adult, Larval And Juvenile Scallops In An Estuary

NASA Astrophysics Data System (ADS)

Bayer, S.; Wahle, R.; Brooks, D. A.; Brady, D. C.

2016-02-01

The giant sea scallop, Placopecten magellanicus, is a commercially valuable sedentary broadcast spawner that occupies offshore banks and coastal bays and estuaries in the Northwest Atlantic. Although area closures have helped repopulate depleted scallop populations, little is known about whether populations at densities that yield larvae supply local or distant populations. Surveying scallop populations in the Damariscotta River estuary in Maine during the 2013 and 2014 spawning seasons, and settling out spat bags to collect settling larvae along the gradient of the estuary, we were able to compare adult densities to newly settled juvenile (`spat') abundance. Using the location where we found a high density of adults, we incorporated previously published behavior, pelagic larval duration, wind and current data into a particle dispersal model within the estuary to determine likely sinks for larvae from the 2013 and 2014 spawning seasons. Preliminary model simulations demonstrate where in the estuary swimming is effective in affecting water column position for larvae, and that most larvae are retained much closer to the mouth of the estuary than previously expected. Combining larval dispersal modeling with empirical data on adult densities and spat settlement on the scale of an embayment or estuary may be helpful in determining sources, sinks and areas that are both sources and sinks for shellfish species that are endangered or economically critical. This may aid in determining small area closures or Marine Protected Areas along coastal regions in the Gulf of Maine and beyond.

[Population estimates and conservation of felids (Carnivora: Felidae) in Northern Quintana Roo, Mexico].

PubMed

Ávila-Nájera, Dulce María; Chávez, Cuauhtémoc; Lazcano-Barrero, Marco A; Pérez-Elizalde, Sergio; Alcántara-Carbajal, José Luis

2015-09-01

Wildlife density estimates provide an idea of the current state of populations, and in some cases, reflect the conservation status of ecosystems, essential aspects for effective management actions. In Mexico, several regions have been identified as high priority areas for the conservation of species that have some level of risk, like the Yucatan Peninsula (YP), where the country has the largest population of jaguars. However, little is known about the current status of threatened and endangered felids, which coexist in the Northeastern portion of the Peninsula. Our objective was to estimate the wild cats' density population over time at El Eden Ecological Reserve (EEER) and its surrounding areas. Camera trap surveys over four years (2008, 2010, 2011 and 2012) were conducted, and data were obtained with the use of capture-recapture models for closed populations (CAPTURE + MMDM or 1/2 MMDM), and the spatially explicit capture-recapture model (SPACECAP). The species studied were jaguar (Panthera onca), puma (Puma concolor), ocelot (Leopardus pardalis), jaguarundi (Puma yaguaroundi) and margay (Leopardus wiedii). Capture frequency was obtained for all five species and the density for three (individuals/100km2). The density estimated with The Mean Maximum Distance Moved (MMDM), CAPTURE, ranged from 1.2 to 2.6 for jaguars, from 1.7 to 4.3 for pumas and from 1.4 to 13.8 for ocelots. The density estimates in SPACECAP ranged from 0.7 to 3.6 for jaguars, from 1.8 to 5.2 for pumas and 2.1 to 5.1 for ocelots. Spatially explicit capture recapture (SECR) methods in SPACECAP were less likely to overestimate densities, making it a useful tool in the planning and decision making process for the conservation of these species. The Northeastern portion of the Yucatan Peninsula maintains high populations of cats, the EEER and its surrounding areas are valuable sites for the conservation of this group of predators. Rev. Biol.

Potential misuse of avian density as a conservation metric

USGS Publications Warehouse

Skagen, Susan K.; Yackel Adams, Amy A.

2011-01-01

Effective conservation metrics are needed to evaluate the success of management in a rapidly changing world. Reproductive rates and densities of breeding birds (as a surrogate for reproductive rate) have been used to indicate the quality of avian breeding habitat, but the underlying assumptions of these metrics rarely have been examined. When birds are attracted to breeding areas in part by the presence of conspecifics and when breeding in groups influences predation rates, the effectiveness of density and reproductive rate as indicators of habitat quality is reduced. It is beneficial to clearly distinguish between individual- and population-level processes when evaluating habitat quality. We use the term reproductive rate to refer to both levels and further distinguish among levels by using the terms per capita fecundity (number of female offspring per female per year, individual level) and population growth rate (the product of density and per capita fecundity, population level). We predicted how density and reproductive rate interact over time under density-independent and density-dependent scenarios, assuming the ideal free distribution model of how birds settle in breeding habitats. We predicted population density of small populations would be correlated positively with both per capita fecundity and population growth rate due to the Allee effect. For populations in the density-dependent growth phase, we predicted no relation between density and per capita fecundity (because individuals in all patches will equilibrate to the same success rate) and a positive relation between density and population growth rate. Several ecological theories collectively suggest that positive correlations between density and per capita fecundity would be difficult to detect. We constructed a decision tree to guide interpretation of positive, neutral, nonlinear, and negative relations between density and reproductive rates at individual and population levels. ?? 2010 Society for Conservation Biology.

Spatial distribution and health risk assessment of toxic metals associated with receptor population density in street dust: a case study of Xiandao District, Changsha, Middle China.

PubMed

Li, Fei; Huang, Jinhui; Zeng, Guangming; Huang, Xiaolong; Liu, Wenchu; Wu, Haipeng; Yuan, Yujie; He, Xiaoxiao; Lai, Mingyong

2015-05-01

Spatial characteristics of the properties (dust organic material and pH), concentrations, and enrichment levels of toxic metals (Ni, Hg, Mn and As) in street dust from Xiandao District (Middle China) were investigated. Method of incorporating receptor population density into noncarcinogenic health risk assessment based on local land use map and geostatistics was developed to identify their priority pollutants/regions of concern. Mean enrichment factors of studied metals decreased in the order of Hg ≈ As > Mn > Ni. For noncarcinogenic effects, the exposure pathway which resulted in the highest levels of exposure risk for children and adults was ingestion except Hg (inhalation of vapors), followed by dermal contact and inhalation. Hazard indexes (HIs) for As, Hg, Mn, and Ni to children and adults revealed the following order: As > Hg > Mn > Ni. Mean HI for As exceeded safe level (1) for children, and the maximum HI (0.99) for Hg was most approached the safe level. Priority regions of concern were indentified in A region at each residential population density and the areas of B at high and moderate residential population density for As and the high residential density area within A region for Hg, respectively. The developed method was proved useful due to its improvement on previous study for making the priority areas of environmental management spatially hierarchical and thus reducing the probability of excessive environmental management.

The role of population density on the impact of urbaniza-tion on GHG emissions in China

NASA Astrophysics Data System (ADS)

Liu, Yonghong; Gao, Chaochao; Lu, Yingying

2017-04-01

Urbanization directly drives rural to urban population migration and indirectly causes west to east migration in China, two phenomena that may significantly impact China's greenhouse gas emissions given its huge population and vast difference between the western rural and eastern urban areas. These two phenomena were analyzed by using emissions as a per capita term, and extending the impact from the traditional urbanization rate effect to include population density effect. The results show that population density has actually been the dominant demographic player in changing per capita emissions for the past two decades in China, and its elasticity changed from positive in economically less-developed provinces to negative for the developed provinces. This study provides a new perspective in the study of the relationship between urbanization and greenhouse gas emissions, and the results indicate that population density change should be taken into account to accurately assess the impact of urbanization.

Spatio-Temporal Variability of Urban Heat Island and Urban Mobility

NASA Astrophysics Data System (ADS)

Kar, B.; Omitaomu, O.

2017-12-01

A 2016 report by the U.S. Census stated that while the rural areas cover 97% of the U.S. landmass, these areas house only 19.7% of the nation's population. Given that the U.S. coastal counties are home to more than 50% of the U.S. population, these urban areas are clustered along the coast that is susceptible to sea level rise induced impacts. In light of increasing climate variability and extreme events, it is pertinent to understand the Urban Heat Island (UHI) effect that results from increasing population density and mobility in the urban areas, and that contributes to increased energy consumption and temperature as well as unmitigated flooding events. For example, in Illinois, warmer summers contribute to heavy precipitation that overwhelms the region's drainage capacity. This study focuses on understanding the spatio-temporal variability of the relationship between population density and mobility distribution, and creation of UHI due to temperature change in selected cities across the U.S. This knowledge will help us understand the role of UHI in energy-water nexus in urban areas, specifically, energy consumption.

Baird's tapir density in high elevation forests of the Talamanca region of Costa Rica.

PubMed

González-Maya, José F; Schipper, Jan; Polidoro, Beth; Hoepker, Annelie; Zárrate-Charry, Diego; Belant, Jerrold L

2012-12-01

Baird's tapir (Tapirus bairdii) is currently endangered throughout its neotropical range with an expected population decline >50% in the next 30 years. We present the first density estimation of Baird's tapir for the Talamanca mountains of Costa Rica, and one of the first for the country. Ten stations with paired cameras were established in Valle del Silencio within Parque Internacional La Amistad (PILA). Seventy-seven tapir pictures of 15 individuals comprising 25 capture-recapture events were analyzed using mark-recapture techniques. The 100% minimum convex polygon of the sampled area was 5.7 km(2) and the effective sampled area using half mean maximum distances moved by tapirs was 7.16 km(2) . We estimated a tapir density of 2.93 individuals/km(2) which represents the highest density reported for this species. Intermountain valleys can represent unique and important habitats for large mammal species. However, the extent of isolation of this population, potentially constrained by steep slopes of the cordillera, remains unknown. Further genetic and movement studies are required to understand meta-population dynamics and connectivity between lowland and highland areas for Baird's tapir conservation in Costa Rica. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

A geographic analysis of population density thresholds in the influenza pandemic of 1918-19.

PubMed

Chandra, Siddharth; Kassens-Noor, Eva; Kuljanin, Goran; Vertalka, Joshua

2013-02-20

Geographic variables play an important role in the study of epidemics. The role of one such variable, population density, in the spread of influenza is controversial. Prior studies have tested for such a role using arbitrary thresholds for population density above or below which places are hypothesized to have higher or lower mortality. The results of such studies are mixed. The objective of this study is to estimate, rather than assume, a threshold level of population density that separates low-density regions from high-density regions on the basis of population loss during an influenza pandemic. We study the case of the influenza pandemic of 1918-19 in India, where over 15 million people died in the short span of less than one year. Using data from six censuses for 199 districts of India (n=1194), the country with the largest number of deaths from the influenza of 1918-19, we use a sample-splitting method embedded within a population growth model that explicitly quantifies population loss from the pandemic to estimate a threshold level of population density that separates low-density districts from high-density districts. The results demonstrate a threshold level of population density of 175 people per square mile. A concurrent finding is that districts on the low side of the threshold experienced rates of population loss (3.72%) that were lower than districts on the high side of the threshold (4.69%). This paper introduces a useful analytic tool to the health geographic literature. It illustrates an application of the tool to demonstrate that it can be useful for pandemic awareness and preparedness efforts. Specifically, it estimates a level of population density above which policies to socially distance, redistribute or quarantine populations are likely to be more effective than they are for areas with population densities that lie below the threshold.

A geographic analysis of population density thresholds in the influenza pandemic of 1918–19

PubMed Central

2013-01-01

Background Geographic variables play an important role in the study of epidemics. The role of one such variable, population density, in the spread of influenza is controversial. Prior studies have tested for such a role using arbitrary thresholds for population density above or below which places are hypothesized to have higher or lower mortality. The results of such studies are mixed. The objective of this study is to estimate, rather than assume, a threshold level of population density that separates low-density regions from high-density regions on the basis of population loss during an influenza pandemic. We study the case of the influenza pandemic of 1918–19 in India, where over 15 million people died in the short span of less than one year. Methods Using data from six censuses for 199 districts of India (n=1194), the country with the largest number of deaths from the influenza of 1918–19, we use a sample-splitting method embedded within a population growth model that explicitly quantifies population loss from the pandemic to estimate a threshold level of population density that separates low-density districts from high-density districts. Results The results demonstrate a threshold level of population density of 175 people per square mile. A concurrent finding is that districts on the low side of the threshold experienced rates of population loss (3.72%) that were lower than districts on the high side of the threshold (4.69%). Conclusions This paper introduces a useful analytic tool to the health geographic literature. It illustrates an application of the tool to demonstrate that it can be useful for pandemic awareness and preparedness efforts. Specifically, it estimates a level of population density above which policies to socially distance, redistribute or quarantine populations are likely to be more effective than they are for areas with population densities that lie below the threshold. PMID:23425498

Using regional bird density distribution models to evaluate protected area networks and inform conservation planning

Treesearch

John D. Alexander; Jaime L. Stephens; Sam Veloz; Leo Salas; Josée S. Rousseau; C. John Ralph; Daniel A. Sarr

2017-01-01

As data about populations of indicator species become available, proactive strategies that improve representation of biological diversity within protected area networks should consider finer-scaled evaluations, especially in regions identified as important through course-scale analyses. We use density distribution models derived from a robust regional bird...

Challenges of DNA-based mark-recapture studies of American black bears

USGS Publications Warehouse

Settlage, K.E.; Van Manen, F.T.; Clark, J.D.; King, T.L.

2008-01-01

We explored whether genetic sampling would be feasible to provide a region-wide population estimate for American black bears (Ursus americanus) in the southern Appalachians, USA. Specifically, we determined whether adequate capture probabilities (p >0.20) and population estimates with a low coefficient of variation (CV <20%) could be achieved given typical agency budget and personnel constraints. We extracted DNA from hair collected from baited barbed-wire enclosures sampled over a 10-week period on 2 study areas: a high-density black bear population in a portion of Great Smoky Mountains National Park and a lower density population on National Forest lands in North Carolina, South Carolina, and Georgia. We identified individual bears by their unique genotypes obtained from 9 microsatellite loci. We sampled 129 and 60 different bears in the National Park and National Forest study areas, respectively, and applied closed mark–recapture models to estimate population abundance. Capture probabilities and precision of the population estimates were acceptable only for sampling scenarios for which we pooled weekly sampling periods. We detected capture heterogeneity biases, probably because of inadequate spatial coverage by the hair-trapping grid. The logistical challenges of establishing and checking a sufficiently high density of hair traps make DNA-based estimates of black bears impractical for the southern Appalachian region. Alternatives are to estimate population size for smaller areas, estimate population growth rates or survival using mark–recapture methods, or use independent marking and recapturing techniques to reduce capture heterogeneity.

Recovery of Durvillaea antarctica (Durvilleales) inside and outside Las Cruces Marine Reserve, Chile.

PubMed

Castilla, J C; Campo, M A; Bustamante, R H

2007-07-01

We present the results for over two decades of monitoring on intertidal food-gatherers and the population of the low rocky shore dweller kelp Durvillaea antarctica, a short-distance disperser, inside and outside the no-take marine reserve, Estacion Costera de Investigaciones Marinas (ECIM), at Las Cruces, central Chile. It was hypothesized that protection of an initially extremely depleted population would recover by recolonizing first the no-take area and then adjacent non-protected (exploited) areas. We found that recovery of D. antarctica occurred slowly inside ECIM, with increase in density and biomass, of up to three orders of magnitude as compared to an adjacent non-protected area, which showed approximately 2-yr delay. These results suggest that the kelp population inside ECIM was likely regulated via intraspecific competition, which did not occur outside. Results showed no evidence for juvenile vs. adult density dependence other than a weak relationship for the central area of ECIM. These findings also suggest that the population recovery and cross-boundary seeding subsides affected the population dynamics. Understanding these dynamics may enhance management and conservation policies. Our work highlights the critical value of baseline and long-term comparative studies in marine no-take protected and non-protected areas for understanding how population processes respond to human and conservation practices.

A population model of the impact of a rodenticide containing strychnine on Great Basin Gophersnakes (Pituophis catenifer deserticola).

PubMed

Bishop, Christine A; Williams, Kathleen E; Kirk, David A; Nantel, Patrick; Reed, Eric; Elliott, John E

2016-09-01

Strychnine is a neurotoxin and an active ingredient in some rodenticides which are placed in burrows to suppress pocket gopher (Thomomys talpoides) populations in range and crop land in western North America. The population level impact was modelled of the use of strychnine-based rodenticides on a non-target snake species, the Great Basin Gophersnake (Pituophis catenifer deserticola), which is a predator of pocket gopher and a Species at Risk in Canada. Using information on population density, demographics, and movement and habitat suitability for the Gophersnake living in an agricultural valley in BC, Canada, we estimated the impact of the poisoning of adult snakes on the long-term population size. To determine the area where Gophersnakes could be exposed to strychnine, we used vendor records of a rodenticide, and quantified the landcover areas of orchards and vineyards where the compound was most commonly applied. GIS analysis determined the areas of overlap between those agricultural lands and suitable habitats used by Gophersnakes. Stage-based population matrix models revealed that in a low density (0.1/ha) population scenario, a diet of one pocket gopher per year wherein 10 % of them carried enough strychnine to kill an adult snake could cause the loss of 2 females annually from the population and this would reduce the population by 35.3 % in 25 years. Under the same dietary exposure, up to 35 females could die per year in a high density (0.4/ha) population which would result in a loss of 50 % of adults in 25 years.

Assessing strategies to reconcile agriculture and bird conservation in the temperate grasslands of South America.

PubMed

Dotta, G; Phalan, B; Silva, T W; Green, R; Balmford, A

2016-06-01

Globally, agriculture is the greatest source of threat to biodiversity, through both ongoing conversion of natural habitat and intensification of existing farmland. Land sparing and land sharing have been suggested as alternative approaches to reconcile this threat with the need for land to produce food. To examine which approach holds most promise for grassland species, we examined how bird population densities changed with farm yield (production per unit area) in the Campos of Brazil and Uruguay. We obtained information on biodiversity and crop yields from 24 sites that differed in agricultural yield. Density-yield functions were fitted for 121 bird species to describe the response of population densities to increasing farm yield, measured in terms of both food energy and profit. We categorized individual species according to how their population changed across the yield gradient as being positively or negatively affected by farming and according to whether the species' total population size was greater under land-sparing, land-sharing, or an intermediate strategy. Irrespective of the yield, most species were negatively affected by farming. Increasing yields reduced densities of approximately 80% of bird species. We estimated land sparing would result in larger populations than other sorts of strategies for 67% to 70% of negatively affected species, given current production levels, including three threatened species. This suggests that increasing yields in some areas while reducing grazing to low levels elsewhere may be the best option for bird conservation in these grasslands. Implementing such an approach would require conservation and production policies to be explicitly linked to support yield increases in farmed areas and concurrently guarantee that larger areas of lightly grazed natural grasslands are set aside for conservation. © 2015 Society for Conservation Biology.

Population Growth and a Sustainable Environment.

ERIC Educational Resources Information Center

Mortimore, Michael; Tiffen, Mary

1994-01-01

Provides a history of farming practices in a densely populated area of Kenya where a recent study of the resource management practices showed positive, not negative, influences of increasing population density on both environmental conservation and productivity. (LZ)

Mediating Effects of Social Support and Internalized Homonegativity on the Association Between Population Density and Mental Health Among Gay and Bisexual Men.

PubMed

Cain, Demetria N; Mirzayi, Chloe; Rendina, H Jonathon; Ventuneac, Ana; Grov, Christian; Parsons, Jeffrey T

2017-10-01

Depression negatively impacts the health and well-being of gay and bisexual men (GBM). However, little is known about the contexts in which rural GBM live relative to those living in urban areas and their overall mental health. The aim of this study was to examine associations between population density and depressive symptoms and the role of internalized homonegativity and social support as potential mediators. A nationally representative sample of 1071 GBM (mean age = 40.24) was enrolled. Participants provided their zip codes, which were categorized according to population density and rank-normalized. In a path analysis model adjusted for race/ethnicity, college education, age, and relationship status, higher population density was significantly associated with increased social support (B = 0.11, P = 0.002) and decreased internalized homonegativity (B = -0.06, P < 0.001). In turn, lower social support (B = -2.93, P < 0.001) and greater internalized homonegativity (B = 4.93, P < 0.001) were significantly associated with greater depressive symptoms. The indirect effects of population density on depression through social support (B = -0.33, P < 0.001) and internalized homonegativity (B = -0.31, P < 0.001) were statistically significant, suggesting evidence for mediation of the effects. These results indicate that living in less inhabited areas acts on depressive symptoms through mechanisms of lower social support and higher internalized homonegativity. These findings suggest that social contexts in which GBM live can affect mental health outcomes and indicate the need for further support and inclusion of GBM, especially in less inhabited areas.

Mediating Effects of Social Support and Internalized Homonegativity on the Association Between Population Density and Mental Health Among Gay and Bisexual Men

PubMed Central

Cain, Demetria N.; Mirzayi, Chloe; Rendina, H. Jonathon; Ventuneac, Ana; Grov, Christian

2017-01-01

Abstract Purpose: Depression negatively impacts the health and well-being of gay and bisexual men (GBM). However, little is known about the contexts in which rural GBM live relative to those living in urban areas and their overall mental health. The aim of this study was to examine associations between population density and depressive symptoms and the role of internalized homonegativity and social support as potential mediators. Methods: A nationally representative sample of 1071 GBM (mean age = 40.24) was enrolled. Participants provided their zip codes, which were categorized according to population density and rank-normalized. Results: In a path analysis model adjusted for race/ethnicity, college education, age, and relationship status, higher population density was significantly associated with increased social support (B = 0.11, P = 0.002) and decreased internalized homonegativity (B = −0.06, P < 0.001). In turn, lower social support (B = −2.93, P < 0.001) and greater internalized homonegativity (B = 4.93, P < 0.001) were significantly associated with greater depressive symptoms. The indirect effects of population density on depression through social support (B = −0.33, P < 0.001) and internalized homonegativity (B = −0.31, P < 0.001) were statistically significant, suggesting evidence for mediation of the effects. Conclusions: These results indicate that living in less inhabited areas acts on depressive symptoms through mechanisms of lower social support and higher internalized homonegativity. These findings suggest that social contexts in which GBM live can affect mental health outcomes and indicate the need for further support and inclusion of GBM, especially in less inhabited areas. PMID:28792886

Spectral Index Properties of millijansky Radio Sources in ATLAS

NASA Astrophysics Data System (ADS)

Randall, Kate; Hopkins, A. M.; Norris, R. P.; Zinn, P.; Middelberg, E.; Mao, M. Y.; Sharp, R. G.

2012-01-01

At the faintest radio flux densities (S1.4GHz < 10 milliJansky (mJy)), the spectral index properties of radio sources are not well constrained. The bright radio source population (S1.4GHz > 10 mJy) is well studied and is predominantly comprised of AGN. At fainter flux densities, particularly into the microJansky regime, star-forming galaxies begin to dominate the radio source population. Understanding these faint radio source populations is essential for understanding galaxy evolution, and the link between AGN and star formation. Conflicting results have recently arisen regarding whether there is a flattening of the average spectral index between a low radio frequency (325 or 610 MHz) and 1.4 GHz at these faint flux densities. To explore this issue, we have investigated the spectral index properties of a new catalogue of 843 MHz radio sources in the ELAIS-S1 (the European Large Area ISO Survey - South 1 Region) field. Our results support previous work showing a tendency towards flatter radio spectra at fainter flux densities. This catalogue is cross-matched to the Australia Telescope Large Area Survey (ATLAS), the widest deep radio survey to date at 1.4 GHz, with complementary 2.3 GHz, optical and infrared Spitzer Wide-area Infra-Red Extragalactic data. The variation of spectral index properties have been explored as a function of redshift, luminosity and flux density. [These new measurements have been used to identify a population of faint Compact Steep Spectrum sources, thought to be one of the earliest stages of the AGN life-cycle. Exploring this population will aid us in understanding the evolution of AGN as a whole.

Study of low density air transportation concepts

NASA Technical Reports Server (NTRS)

Webb, H. M.

1972-01-01

Low density air transport refers to air service to sparsely populated regions. There are two major objectives. The first is to examine those characteristics of sparsely populated areas which pertain to air transportation. This involves determination of geographical, commercial and population trends, as well as those traveler characteristics which affect the viability of air transport in the region. The second objective is to analyze the technical, economic and operational characteristics of low density air service. Two representative, but diverse arenas, West Virginia and Arizona, were selected for analysis: The results indicate that Arizona can support air service under certain assumptions whereas West Virginia cannot.

Annual variation in the distribution, abundance, and habitat response of the palila (Loxioides bailleui)

USGS Publications Warehouse

Scott, J.M.; Mountainspring, S.; van Riper, Charles; Kepler, C.B.; Jacobi, J.D.; Burr, T.A.; Giffen, J.G.

1984-01-01

We studied the distribution, population size, and habitat response of the Palila (Loxioides bailleui) during the 1980-1984 nonbreeding seasons to infer factors that limit the population and to develop management strategies. Distribution was fairly constant from year to year. Palila were confined to the subalpine woodland on Mauna Kea on the island of Hawaii, occurred between 2,000 and 2,850 m elevation, and reached highest densities on the southwest slopes. The population showed large annual fluctuations, from 6,400 birds in 1981 to 2,000 in 1984. The width of woodland was the most important variable in determining habitat response. Palila were more common in areas with greater crown cover, taller trees, and a higher proportion of native plants in the understory. Annual variation in Palila density within a habitat reflected variation in levels of their staple food, mamane pods. The main limiting factors of the population appeared to be the availability of good habitat and levels of their staple food. Palila had strongly depressed densities in the Pohakuloa flats area. This low density could not be explained by gross habitat features or food levels. Site tenacity, thermal stress, disturbance, and disease were hypothesized explanations. Our study indicated that the most effective management strategies would be the removal of feral ungulates and certain noxious plants from Palila habitat and the extension of the woodland zone to areas now intensively grazed.

Population density predicts outcome from out-of-hospital cardiac arrest in Victoria, Australia.

PubMed

Nehme, Ziad; Andrew, Emily; Cameron, Peter A; Bray, Janet E; Bernard, Stephen A; Meredith, Ian T; Smith, Karen

2014-05-05

To examine the impact of population density on incidence and outcome of out-of-hospital cardiac arrest (OHCA). Data were extracted from the Victorian Ambulance Cardiac Arrest Registry for all adult OHCA cases of presumed cardiac aetiology attended by the emergency medical service (EMS) between 1 January 2003 and 31 December 2011. Cases were allocated into one of five population density groups according to their statistical local area: very low density (≤ 10 people/km(2)), low density (11-200 people/km(2)), medium density (201-1000 people/km(2)), high density (1001-3000 people/km(2)), and very high density (> 3000 people/km(2)). Survival to hospital and survival to hospital discharge. The EMS attended 27 705 adult presumed cardiac OHCA cases across 204 Victorian regions. In 12 007 of these (43.3%), resuscitation was attempted by the EMS. Incidence was lower and arrest characteristics were consistently less favourable for lower population density groups. Survival outcomes, including return of spontaneous circulation, survival to hospital and survival to hospital discharge, were significantly poorer in less densely populated groups (P < 0.001 for all comparisons). When compared with very low density populations, the risk-adjusted odds ratios of surviving to hospital discharge were: low density, 1.88 (95% CI, 1.15-3.07); medium density, 2.49 (95% CI, 1.55-4.02); high density, 3.47 (95% CI, 2.20-5.48) and very high density, 4.32 (95% CI, 2.67-6.99). Population density is independently associated with survival after OHCA, and significant variation in the incidence and characteristics of these events are observed across the state.

Crop diversity loss as primary cause of grey partridge and common pheasant decline in Lower Saxony, Germany.

PubMed

Ronnenberg, Katrin; Strauß, Egbert; Siebert, Ursula

2016-09-09

The grey partridge (Perdix perdix) and the common pheasant (Phasianus colchicus) are galliform birds typical of arable lands in Central Europe and exhibit a partly dramatic negative population trend. In order to understand general habitat preferences we modelled grey partridge and common pheasant densities over the entire range of Lower Saxony. Spatially explicit developments in bird densities were modelled using spatially explicit trends of crop cultivation. Pheasant and grey partridge densities counted annually by over 8000 hunting district holders over 10 years in a range of 3.7 Mio ha constitute a unique dataset (wildlife survey of Lower Saxony). Data on main landscape groups, functional groups of agricultural crops (consisting of 9.5 million fields compiled by the Integrated Administration and Control System) and landscape features were aggregated to 420 municipalities. To model linear 8 or 10 year population trends (for common pheasant and grey partridge respectively) we use rho correlation coefficients of densities, but also rho coefficients of agricultural crops. All models confirm a dramatic decline in population densities. The habitat model for the grey partridge shows avoidance of municipalities with a high proportion of woodland and water areas, but a preference for areas with a high proportion of winter grains and high crop diversity. The trend model confirms these findings with a linear positive effect of diversity on grey partridge population development. Similarly, the pheasant avoids wooded areas but showed some preference for municipalities with open water. The effect of maize was found to be positive at medium densities, but negative at very high proportions. Winter grains, landscape features and high crop diversity are favorable. The positive effect of winter grains and higher crop diversity is also supported by the trend model. The results show the strong importance of diverse crop cultivation. Most incentives favor the cultivation of specific crops, which results in large areas of monocultures. The results confirm the importance of sustainable agricultural policies.

Relationship between habitat type, fire frequency, and Amblyomma americanum populations in east-central Alabama.

PubMed

Willis, Damien; Carter, Robert; Murdock, Chris; Blair, Benjie

2012-12-01

Ticks were collected from 20 sites in the Calhoun, Cherokee, and Cleburne Counties in east-central Alabama areas to determine the relationship between plant physiognomy, environmental variables, and tick populations. Sites investigated included various burning regimes, wildland-urban-interface (WUI), a college campus, and an unmanaged area. Amblyomma americanum (L.) (Acari: Ixodidae) dominated the tick population while Ixodes scapularis Say was not encountered. There were complex differences in tick populations among site conditions. After prescribed burning, the tick population size was small but was larger in subsequent 2- and 5-year post-burn sites. An increase in Odocoileus virginianus foraging in recently burned sites is likely responsible for this phenomenon. WUI areas had the largest tick populations likely due to Odocoileus virginianus activity in an area that provides cover, forage, and a connection to a wildlife refuge. It is possible that the likelihood of humans coming in contact with ticks and tick-borne diseases is greater in WUI areas than in unbroken contiguous forest. A. americanum showed a positive correlation with percent cover of grass and leaf litter mass and a negative relationship with pine sapling density. Variables expected to be strongly correlated with A. americanum populations such as soil moisture, canopy closure, and tree density were found to have weak correlations. © 2012 The Society for Vector Ecology.

Age- and sex-specific mortality and population structure in sea otters

USGS Publications Warehouse

Bodkin, James L.; Burdin, A.M.; Ryazanov, D.A.

2000-01-01

We used 742 beach-cast carcasses to characterize age- and sex-specific sea otter mortality during the winter of 1990-1991 at Bering Island, Russia. We also examined 363 carcasses recovered after the 1989 grounding of the T/V Exxon Valdez, to characterize age and sex composition in the living western Prince William Sound (WPWS) sea otter population. At Bering Island, mortality was male-biased (81%), and 75% were adults. The WPWS population was female-biased (59%) and most animals were subadult (79% of the males and 45% of the females). In the decade prior to 1990-1991 we found increasing sea otter densities (particularly among males), declining prey resources, and declining weights in adult male sea otters at Bering Island. Our findings suggest the increased mortality at Bering Island in 1990-1991 was a density-dependent population response. We propose male-maintained breeding territories and exclusion of juvenile females by adult females, providing a mechanism for maintaining densities in female areas below densities in male areas and for potentially moderating the effects of prey reductions on the female population. Increased adult male mortality at Bering Island in 1990-1991 likely modified the sex and age class structure there toward that observed in Prince William Sound.

Natal movement in juvenile Atlantic salmon: a body size-dependent strategy?

Treesearch

Sigurd Einum; Anders G. Finstad; Grethe Robertsen; Keith H. Nislow; Simon McKelvey; John D. Armstrong

2012-01-01

If competitive ability depends on body size, then the optimal natal movement from areas of high local population density can also be predicted to be size-dependent. Specifically, small, competitively-inferior individuals would be expected to benefit most from moving to areas of lower local density. Here we evaluate whether individual variation in natal movement...

Anthropogenically-Mediated Density Dependence in a Declining Farmland Bird

PubMed Central

Dunn, Jenny C.; Hamer, Keith C.; Benton, Tim G.

2015-01-01

Land management intrinsically influences the distribution of animals and can consequently alter the potential for density-dependent processes to act within populations. For declining species, high densities of breeding territories are typically considered to represent productive populations. However, as density-dependent effects of food limitation or predator pressure may occur (especially when species are dependent upon separate nesting and foraging habitats), high territory density may limit per-capita productivity. Here, we use a declining but widespread European farmland bird, the yellowhammer Emberiza citrinella L., as a model system to test whether higher territory densities result in lower fledging success, parental provisioning rates or nestling growth rates compared to lower densities. Organic landscapes held higher territory densities, but nests on organic farms fledged fewer nestlings, translating to a 5 times higher rate of population shrinkage on organic farms compared to conventional. In addition, when parental provisioning behaviour was not restricted by predation risk (i.e., at times of low corvid activity), nestling provisioning rates were higher at lower territory densities, resulting in a much greater increase in nestling mass in low density areas, suggesting that food limitation occurred at high densities. These findings in turn suggest an ecological trap, whereby preferred nesting habitat does not provide sufficient food for rearing nestlings at high population density, creating a population sink. Habitat management for farmland birds should focus not simply on creating a high nesting density, but also on ensuring heterogeneous habitats to provide food resources in close proximity to nesting birds, even if this occurs through potentially restricting overall nest density but increasing population-level breeding success. PMID:26431173

Fishing for lobsters indirectly increases epidemics in sea urchins

USGS Publications Warehouse

Lafferty, Kevin D.

2004-01-01

Two ecological paradigms, the trophic cascade and the host-density threshold in disease, interact in the kelp-forest ecosystem to structure the community. To investigate what happens when a trophic cascade pushes a host population over a host-threshold density, I analyzed a 20-year data set of kelp forest communities at 16 sites in the region of the Channel Islands National Park, California, USA. Historically, lobsters, and perhaps other predators, kept urchin populations at low levels and kelp forests developed a community-level trophic cascade. In geographic areas where the main predators on urchins were fished, urchin populations increased to the extent that they overgrazed algae and starvation eventually limited urchin-population growth. Despite the limitation of urchin population size by food availability, urchin densities, at times, well exceeded the host-density threshold for epidemics. An urchin-specific bacterial disease entered the region after 1992 and acted as a density-dependent mortality source. Dense populations were more likely to experience epidemics and suffer higher mortality. Disease did not reduce the urchin population at a site to the density that predators previously did. Therefore, disease did not fully replace predators in the trophic cascade. These results indicate how fishing top predators can indirectly favor disease transmission in prey populations.

Varying impacts of alcohol outlet densities on violent assaults: explaining differences across neighborhoods.

PubMed

Mair, Christina; Gruenewald, Paul J; Ponicki, William R; Remer, Lillian

2013-01-01

Groups of potentially violent drinkers may frequent areas of communities with large numbers of alcohol outlets, especially bars, leading to greater rates of alcohol-related assaults. This study assessed direct and moderating effects of bar densities on assaults across neighborhoods. We analyzed longitudinal population data relating alcohol outlet densities (total outlet density, proportion bars/pubs, proportion off-premise outlets) to hospitalizations for assault injuries in California across residential ZIP code areas from 1995 through 2008 (23,213 space-time units). Because few ZIP codes were consistently defined over 14 years and these units are not independent, corrections for unit misalignment and spatial autocorrelation were implemented using Bayesian space-time conditional autoregressive models. Assaults were related to outlet densities in local and surrounding areas, the mix of outlet types, and neighborhood characteristics. The addition of one outlet per square mile was related to a small 0.23% increase in assaults. A 10% greater proportion of bars in a ZIP code was related to 7.5% greater assaults, whereas a 10% greater proportion of bars in surrounding areas was related to 6.2% greater assaults. The impacts of bars were much greater in areas with low incomes and dense populations. The effect of bar density on assault injuries was well supported and positive, and the magnitude of the effect varied by neighborhood characteristics. Posterior distributions from these models enabled the identification of locations most vulnerable to problems related to alcohol outlets.

Population condition analysis of Jakarta land deformation area

NASA Astrophysics Data System (ADS)

Putri, R. F.; Wibirama, S.; Sukamdi; Giyarsih, S. R.

2018-04-01

Jakarta is located in the North West area of West Java Province which geographically positioned on 106°33’00”-107°00’00”BT and 5°48’30”-6°24’00”LS. Land subsidence has occured in several types of landuse such as trade, industrial and settlement area of the urban area of Jakarta. The land subsidence disaster is one of the consequences of building and road construction in Jakarta. This is caused by massive groundwater utilization and failure in landuse planning. This study aim to analyze the population density and settlement pattern in the urban area of Jakarta which the occurence of land subsidence has been detected. It is important to understand landuse and settlement planning processes in the area which land subsidence occured. Detection of land subsidence distribution become a necessary parameter in landuse planning. While the land subsidence area detected using Differential Synthetic Aperture Radar (DInSAR) method. The result shows the area which land subsidence occured has a very high population density and clustered and linear settlement pattern. This area is mainly used as industrial, trade, and settlement.

The urban environmental gradient: Anthropogenic influences on the spatial and temporal distributions of lead and zinc in sediments

USGS Publications Warehouse

Callender, Edward; Rice, Karen C.

2000-01-01

Urban settings are a focal point for environmental contamination due to emissions from industrial and municipal activities and the widespread use of motor vehicles. As part of the National Water-Quality Assessment Program of the U.S. Geological Survey, streambed-sediment and dated reservoir-sediment samples were collected from the Chattahoochee River Basin and analyzed for total lead (Pb) and zinc (Zn) concentrations. The sampling transect extends from northern Georgia, through Atlanta, to the Gulf of Mexico and reflects a steep gradient in population density from nearly 1000 people/km2 in the Atlanta Metropolitan Area to fewer than 50 people/km2 in rural areas of southern Georgia and northern Florida. Correlations among population density, traffic density, and total and anthropogenic Pb and Zn concentrations indicate that population density is strongly related to traffic density and is a predictor of Pb and Zn concentrations in the environment derived from anthropogenic activities. Differences in the distributions of total Pb and Zn concentrations along the urban−suburban−rural gradient from Atlanta to the Florida Panhandle are related to temporal and spatial processes. That is, with the removal of leaded gasoline starting in the late 1970s, peak Pb concentrations have decreased to the present. Conversely, increased vehicular usage has kept Zn concentrations elevated in runoff from population centers, which is reflected in the continued enrichment of Zn in aquatic sediments. Sediments from rural areas also contain elevated concentrations of Zn, possibly in response to substantial power plant emissions for the region, as well as vehicular traffic.

Model-based estimators of density and connectivity to inform conservation of spatially structured populations

USGS Publications Warehouse

Morin, Dana J.; Fuller, Angela K.; Royle, J. Andrew; Sutherland, Chris

2017-01-01

Conservation and management of spatially structured populations is challenging because solutions must consider where individuals are located, but also differential individual space use as a result of landscape heterogeneity. A recent extension of spatial capture–recapture (SCR) models, the ecological distance model, uses spatial encounter histories of individuals (e.g., a record of where individuals are detected across space, often sequenced over multiple sampling occasions), to estimate the relationship between space use and characteristics of a landscape, allowing simultaneous estimation of both local densities of individuals across space and connectivity at the scale of individual movement. We developed two model-based estimators derived from the SCR ecological distance model to quantify connectivity over a continuous surface: (1) potential connectivity—a metric of the connectivity of areas based on resistance to individual movement; and (2) density-weighted connectivity (DWC)—potential connectivity weighted by estimated density. Estimates of potential connectivity and DWC can provide spatial representations of areas that are most important for the conservation of threatened species, or management of abundant populations (i.e., areas with high density and landscape connectivity), and thus generate predictions that have great potential to inform conservation and management actions. We used a simulation study with a stationary trap design across a range of landscape resistance scenarios to evaluate how well our model estimates resistance, potential connectivity, and DWC. Correlation between true and estimated potential connectivity was high, and there was positive correlation and high spatial accuracy between estimated DWC and true DWC. We applied our approach to data collected from a population of black bears in New York, and found that forested areas represented low levels of resistance for black bears. We demonstrate that formal inference about measures of landscape connectivity can be achieved from standard methods of studying animal populations which yield individual encounter history data such as camera trapping. Resulting biological parameters including resistance, potential connectivity, and DWC estimate the spatial distribution and connectivity of the population within a statistical framework, and we outline applications to many possible conservation and management problems.

Long-Term Trends in Abundance and Distribution of Manatees (Trichechus Manatus) in the Northern Banana River, Brevard County, Florida

NASA Technical Reports Server (NTRS)

Provancha, J. A.; Provancha, M. J.

1988-01-01

Four aerial survey projects were conducted between 1977 and 1986 to determine the abundance, density and distribution of West Indian manatees (Trichechus manatus), in the northern Banana River, Kennedy Space Center, Florida. Manatee density and distribution within selected portions of the 78.5 sq km study area were determined. Peak numbers of manatees occurred in spring of each year. The maximum counts increased from 56 in 1978 to 297 in 1986. Manatee abundance was lowest in the winter of each year. Mean density per flight increased from 0.52 manatees/sq km in 1977-78 to 2.73/sq km in 1984-86. This increase may reflect increases in the east coast population or shifts in the population distribution. Distributional changes were observed in the study area through time, with a lower percentage of manatees occurring in industrial areas and a correspondingly higher percentage of manatees in nonindustrial areas by 1985.

The effect of area size and predation on the time to extinction of prairie vole populations. simulation studies via SERDYCA: a Spatially-Explicit Individual-Based Model of Rodent Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostova, T; Carlsen, T

2003-11-21

We present a spatially-explicit individual-based computational model of rodent dynamics, customized for the prairie vole species, M. Ochrogaster. The model is based on trophic relationships and represents important features such as territorial competition, mating behavior, density-dependent predation and dispersal out of the modeled spatial region. Vegetation growth and vole fecundity are dependent on climatic components. The results of simulations show that the model correctly predicts the overall temporal dynamics of the population density. Time-series analysis shows a very good match between the periods corresponding to the peak population density frequencies predicted by the model and the ones reported in themore » literature. The model is used to study the relation between persistence, landscape area and predation. We introduce the notions of average time to extinction (ATE) and persistence frequency to quantify persistence. While the ATE decreases with decrease of area, it is a bell-shaped function of the predation level: increasing for 'small' and decreasing for 'large' predation levels.« less

Modeling ecological traps for the control of feral pigs

PubMed Central

Dexter, Nick; McLeod, Steven R

2015-01-01

Ecological traps are habitat sinks that are preferred by dispersing animals but have higher mortality or reduced fecundity compared to source habitats. Theory suggests that if mortality rates are sufficiently high, then ecological traps can result in extinction. An ecological trap may be created when pest animals are controlled in one area, but not in another area of equal habitat quality, and when there is density-dependent immigration from the high-density uncontrolled area to the low-density controlled area. We used a logistic population model to explore how varying the proportion of habitat controlled, control mortality rate, and strength of density-dependent immigration for feral pigs could affect the long-term population abundance and time to extinction. Increasing control mortality, the proportion of habitat controlled and the strength of density-dependent immigration decreased abundance both within and outside the area controlled. At higher levels of these parameters, extinction was achieved for feral pigs. We extended the analysis with a more complex stochastic, interactive model of feral pig dynamics in the Australian rangelands to examine how the same variables as the logistic model affected long-term abundance in the controlled and uncontrolled area and time to extinction. Compared to the logistic model of feral pig dynamics, the stochastic interactive model predicted lower abundances and extinction at lower control mortalities and proportions of habitat controlled. To improve the realism of the stochastic interactive model, we substituted fixed mortality rates with a density-dependent control mortality function, empirically derived from helicopter shooting exercises in Australia. Compared to the stochastic interactive model with fixed mortality rates, the model with the density-dependent control mortality function did not predict as substantial decline in abundance in controlled or uncontrolled areas or extinction for any combination of variables. These models demonstrate that pest eradication is theoretically possible without the pest being controlled throughout its range because of density-dependent immigration into the area controlled. The stronger the density-dependent immigration, the better the overall control in controlled and uncontrolled habitat combined. However, the stronger the density-dependent immigration, the poorer the control in the area controlled. For feral pigs, incorporating environmental stochasticity improves the prospects for eradication, but adding a realistic density-dependent control function eliminates these prospects. PMID:26045954

A multi-scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence

USGS Publications Warehouse

Brennan, Angela K.; Cross, Paul C.; Higgs, Megan D.; Edwards, W. Henry; Scurlock, Brandon M.; Creel, Scott

2014-01-01

Understanding how animal density is related to pathogen transmission is important to develop effective disease control strategies, but requires measuring density at a scale relevant to transmission. However, this is not straightforward or well-studied among large mammals with group sizes that range several orders of magnitude or aggregation patterns that vary across space and time. To address this issue, we examined spatial variation in elk (Cervus canadensis) aggregation patterns and brucellosis across 10 regions in the Greater Yellowstone Area where previous studies suggest the disease may be increasing. We hypothesized that rates of increasing brucellosis would be better related to the frequency of large groups than mean group size or population density, but we examined whether other measures of density would also explain rising seroprevalence. To do this, we measured wintering elk density and group size across multiple spatial and temporal scales from monthly aerial surveys. We used Bayesian hierarchical models and 20 years of serologic data to estimate rates of increase in brucellosis within the 10 regions, and to examine the linear relationships between these estimated rates of increase and multiple measures of aggregation. Brucellosis seroprevalence increased over time in eight regions (one region showed an estimated increase from 0.015 in 1991 to 0.26 in 2011), and these rates of increase were positively related to all measures of aggregation. The relationships were weaker when the analysis was restricted to areas where brucellosis was present for at least two years, potentially because aggregation was related to disease-establishment within a population. Our findings suggest that (1) group size did not explain brucellosis increases any better than population density and (2) some elk populations may have high densities with small groups or lower densities with large groups, but brucellosis is likely to increase in either scenario. In this case, any one control method such as reducing population density or group size may not be sufficient to reduce transmission. This study highlights the importance of examining the density-transmission relationship at multiple scales and across populations before broadly applying disease control strategies.

Impact of overgrazing on the transmission of Echinococcus multilocularis in Tibetan pastoral communities of Sichuan Province, China.

PubMed

Wang, Qian; Xiao, Yong-fu; Vuitton, Dominique A; Schantz, Peter M; Raoul, Francis; Budke, Christine; Campos-Ponce, Maiza; Craig, Philip S; Giraudoux, Patrick

2007-02-05

Overgrazing was assumed to increase the population density of small mammals that are the intermediate hosts of Echinococcus multilocularis, the pathogen of alveolar echinococcosis in the Qinghai Tibet Plateau. This research tested the hypothesis that overgrazing might promote Echinococcus multilocularis transmission through increasing populations of small mammal, intermediate hosts in Tibetan pastoral communities. Grazing practices, small mammal indices and dog Echinococcus multilocularis infection data were collected to analyze the relation between overgrazing and Echinococcus multilocularis transmission using nonparametric tests and multiple stepwise logistic regression. In the investigated area, raising livestock was a key industry. The communal pastures existed and the available forage was deficient for grazing. Open (common) pastures were overgrazed and had higher burrow density of small mammals compared with neighboring fenced (private) pastures; this high overgrazing pressure on the open pastures measured by neighboring fenced area led to higher burrow density of small mammals in open pastures. The median burrow density of small mammals in open pastures was independently associated with nearby canine Echinococcus multilocularis infection (P = 0.003, OR = 1.048). Overgrazing may promote the transmission of Echinococcus multilocularis through increasing the population density of small mammals.

Assessing Urban Streets Network Vulnerability against Earthquake Using GIS - Case Study: 6TH Zone of Tehran

NASA Astrophysics Data System (ADS)

Rastegar, A.

2017-09-01

Great earthquakes cause huge damages to human life. Street networks vulnerability makes the rescue operation to encounter serious difficulties especially at the first 72 hours after the incident. Today, physical expansion and high density of great cities, due to narrow access roads, large distance from medical care centers and location at areas with high seismic risk, will lead to a perilous and unpredictable situation in case of the earthquake. Zone # 6 of Tehran, with 229,980 population (3.6% of city population) and 20 km2 area (3.2% of city area), is one of the main municipal zones of Tehran (Iran center of statistics, 2006). Major land-uses, like ministries, embassies, universities, general hospitals and medical centers, big financial firms and so on, manifest the high importance of this region on local and national scale. In this paper, by employing indexes such as access to medical centers, street inclusion, building and population density, land-use, PGA and building quality, vulnerability degree of street networks in zone #6 against the earthquake is calculated through overlaying maps and data in combination with IHWP method and GIS. This article concludes that buildings alongside the streets with high population and building density, low building quality, far to rescue centers and high level of inclusion represent high rate of vulnerability, compared with other buildings. Also, by moving on from north to south of the zone, the vulnerability increases. Likewise, highways and streets with substantial width and low building and population density hold little values of vulnerability.

Land Use as a Driver of Patterns of Rodenticide Exposure in Modeled Kit Fox Populations

PubMed Central

Nogeire, Theresa M.; Lawler, Joshua J.; Schumaker, Nathan H.; Cypher, Brian L.; Phillips, Scott E.

2015-01-01

Although rodenticides are increasingly regulated, they nonetheless cause poisonings in many non-target wildlife species. Second-generation anticoagulant rodenticide use is common in agricultural and residential landscapes. Here, we use an individual-based population model to assess potential population-wide effects of rodenticide exposures on the endangered San Joaquin kit fox (Vulpes macrotis mutica). We estimate likelihood of rodenticide exposure across the species range for each land cover type based on a database of reported pesticide use and literature. Using a spatially-explicit population model, we find that 36% of modeled kit foxes are likely exposed, resulting in a 7-18% decline in the range-wide modeled kit fox population that can be linked to rodenticide use. Exposures of kit foxes in low-density developed areas accounted for 70% of the population-wide exposures to rodenticides. We conclude that exposures of non-target kit foxes could be greatly mitigated by reducing the use of second-generation anticoagulant rodenticides in low-density developed areas near vulnerable populations. PMID:26244655

Flood Risk Analysis in Denpasar City, Bali, Indonesia

NASA Astrophysics Data System (ADS)

Kusmiyarti, T. B.; Wiguna, P. P. K.; Ratna Dewi, N. K. R.

2018-02-01

Denpasar city is a Capital City of Bali Province and one of the leading tourist destinations in Indonesia. Denpasar area is relatively flat with high rain fall intensity with the domince of settlement. This makes Denpasar City becomes prone area of flood. The aim of this research is to find out the spatial distribution flood hazard and the risk of population which are affected to the flood hazard. Weighting, scoring and overlaying method were used in this research. Six indicators were used to analyze the flood hazard: landuse, rainfall, type of soil, slope, altitute and drainage density. The vulnerability is analyzed per Desa or Kelurahan (Rustic/Neighborhood) with the indicator of age, education and population density. Risk was calculated by multiplied hazard with vulnerability and divided with coping capacity. In this research, coping capacity is determined by the amount of internal budget for each Desa or Kelurahan for development purpose. Flood risk in Denpasar city is divided into five classes, very low risk, low risk, medium risk, high risk and very high risk. Total population with very high risk reached 202478 people or 13.16% of total population. The total area is 780.7 ha or 16.02% from total settlement in Denpasar city. Total population with high risk reached 202478 people or 13.16% of total population. The total area is 780.7 ha or 16.02% from total settlement in Denpasar city. The number of population with medium risk reached 202478 people or 33.51% of total population which occupied 22.95% of total settlements or 1118.18 ha. The total number of population with low risk reached 79435 people or 13.14% of total population with area of low flood risk is 716.89 ha or 14.71% of total settlements in Denpasar City. Very low flood risk with total population at risk reached 19184 people or 31.74% of total population and occupied 2003.54 areas or 41.12% of total areas of settlements.

Potential misuse of avian density as a conservation metric.

PubMed

Skagen, Susan K; Yackel Adams, Amy A

2011-02-01

Effective conservation metrics are needed to evaluate the success of management in a rapidly changing world. Reproductive rates and densities of breeding birds (as a surrogate for reproductive rate) have been used to indicate the quality of avian breeding habitat, but the underlying assumptions of these metrics rarely have been examined. When birds are attracted to breeding areas in part by the presence of conspecifics and when breeding in groups influences predation rates, the effectiveness of density and reproductive rate as indicators of habitat quality is reduced. It is beneficial to clearly distinguish between individual- and population-level processes when evaluating habitat quality. We use the term reproductive rate to refer to both levels and further distinguish among levels by using the terms per capita fecundity (number of female offspring per female per year, individual level) and population growth rate (the product of density and per capita fecundity, population level). We predicted how density and reproductive rate interact over time under density-independent and density-dependent scenarios, assuming the ideal free distribution model of how birds settle in breeding habitats. We predicted population density of small populations would be correlated positively with both per capita fecundity and population growth rate due to the Allee effect. For populations in the density-dependent growth phase, we predicted no relation between density and per capita fecundity (because individuals in all patches will equilibrate to the same success rate) and a positive relation between density and population growth rate. Several ecological theories collectively suggest that positive correlations between density and per capita fecundity would be difficult to detect. We constructed a decision tree to guide interpretation of positive, neutral, nonlinear, and negative relations between density and reproductive rates at individual and population levels. Journal compilation ©2010 Society for Conservation Biology. No claim to original US government works.

Implications of Fine-Grained Habitat Fragmentation and Road Mortality for Jaguar Conservation in the Atlantic Forest, Brazil.

PubMed

Cullen, Laury; Stanton, Jessica C; Lima, Fernando; Uezu, Alexandre; Perilli, Miriam L L; Akçakaya, H Reşit

2016-01-01

Jaguar (Panthera onca) populations in the Upper Paraná River, in the Brazilian Atlantic Forest region, live in a landscape that includes highly fragmented areas as well as relatively intact ones. We developed a model of jaguar habitat suitability in this region, and based on this habitat model, we developed a spatially structured metapopulation model of the jaguar populations in this area to analyze their viability, the potential impact of road mortality on the populations' persistence, and the interaction between road mortality and habitat fragmentation. In more highly fragmented populations, density of jaguars per unit area is lower and density of roads per jaguar is higher. The populations with the most fragmented habitat were predicted to have much lower persistence in the next 100 years when the model included no dispersal, indicating that the persistence of these populations are dependent to a large extent on dispersal from other populations. This, in turn, indicates that the interaction between road mortality and habitat fragmentation may lead to source-sink dynamics, whereby populations with highly fragmented habitat are maintained only by dispersal from populations with less fragmented habitat. This study demonstrates the utility of linking habitat and demographic models in assessing impacts on species living in fragmented landscapes.

Implications of Fine-Grained Habitat Fragmentation and Road Mortality for Jaguar Conservation in the Atlantic Forest, Brazil

PubMed Central

Cullen, Laury; Stanton, Jessica C.; Lima, Fernando; Uezu, Alexandre; Perilli, Miriam L. L.; Akçakaya, H. Reşit

2016-01-01

Jaguar (Panthera onca) populations in the Upper Paraná River, in the Brazilian Atlantic Forest region, live in a landscape that includes highly fragmented areas as well as relatively intact ones. We developed a model of jaguar habitat suitability in this region, and based on this habitat model, we developed a spatially structured metapopulation model of the jaguar populations in this area to analyze their viability, the potential impact of road mortality on the populations' persistence, and the interaction between road mortality and habitat fragmentation. In more highly fragmented populations, density of jaguars per unit area is lower and density of roads per jaguar is higher. The populations with the most fragmented habitat were predicted to have much lower persistence in the next 100 years when the model included no dispersal, indicating that the persistence of these populations are dependent to a large extent on dispersal from other populations. This, in turn, indicates that the interaction between road mortality and habitat fragmentation may lead to source-sink dynamics, whereby populations with highly fragmented habitat are maintained only by dispersal from populations with less fragmented habitat. This study demonstrates the utility of linking habitat and demographic models in assessing impacts on species living in fragmented landscapes. PMID:27973584

Decline of a Rare Moth at Its Last Known English Site: Causes and Lessons for Conservation.

PubMed

Baker, David; Barrett, Sinead; Beale, Colin M; Crawford, Terry J; Ellis, Sam; Gullett, Tallulah; Mayhew, Peter J; Parsons, Mark S; Relf, Penny; Robertson, Paul; Small, Julian; Wainwright, Dave

2016-01-01

The conditions required by rare species are often only approximately known. Monitoring such species over time can help refine management of their protected areas. We report population trends of a rare moth, the Dark Bordered Beauty Epione vespertaria (Linnaeus, 1767) (Lepidoptera: Geometridae) at its last known English site on a protected lowland heath, and those of its host-plant, Salix repens (L.) (Malpighiales: Salicaceae). Between 2007 and 2014, adult moth density reduced by an average of 30-35% annually over the monitored area, and its range over the monitored area contracted in concert. By comparing data from before this decline (2005) with data taken in 2013, we show that the density of host-plants over the monitored area reduced three-fold overall, and ten-fold in the areas of highest host-plant density. In addition, plants were significantly smaller in 2013. In 2005, moth larvae tended to be found on plants that were significantly larger than average at the time. By 2013, far fewer plants were of an equivalent size. This suggests that the rapid decline of the moth population coincides with, and is likely driven by, changes in the host-plant population. Why the host-plant population has changed remains less certain, but fire, frost damage and grazing damage have probably contributed. It is likely that a reduction in grazing pressure in parts of the site would aid host-plant recovery, although grazing remains an important site management activity. Our work confirms the value of constant monitoring of rare or priority insect species, of the risks posed to species with few populations even when their populations are large, of the potential conflict between bespoke management for species and generic management of habitats, and hence the value of refining our knowledge of rare species' requirements so that their needs can be incorporated into the management of protected areas.

A survey of the dog population in rural Bangladesh.

PubMed

Hossain, Moazzem; Ahmed, Kamruddin; Marma, Aung Swi Prue; Hossain, Sohrab; Ali, Mohammad Azmat; Shamsuzzaman, Abul Khair Mohammad; Nishizono, Akira

2013-08-01

Globally, Bangladesh ranks third in the number of human deaths from rabies. Although dogs are the principal known transmitters of rabies and knowledge of dog populations is essential for effective national control and proper planning, dog control programs are scarce in Bangladesh. Our objective was to count dogs in a rural area to understand the dog population of the country. For this purpose we selected six unions of Raipura upazila in Narsingdi district. Dog counting was done by direct observation following accepted guidelines. We determined the mean density of the dog population in Bangladesh to be 14 dog/km(2) (95% CI 3.7, 24) and the human:dog ratio to be 120 (95% CI 55, 184). Our paper contribute to the literature which shows great variation in the human:dog ratio across regions of the developing world. The human:dog ratio depends on the area's human (as well as dog) population, whereas dog density per unit area indicates the true number of dogs. We propose that extrapolating from the human:dog ratios of other regions not be relied upon for estimating dog populations, unless the ratios can be supplemented by actual counts of dogs within the target area. Copyright © 2013 Elsevier B.V. All rights reserved.

Density effect on great tit (Parus major) clutch size intensifies in a polluted environment.

PubMed

Eeva, Tapio; Lehikoinen, Esa

2013-12-01

Long-term data on a great tit (Parus major) population breeding in a metal-polluted zone around a copper-nickel smelter indicate that, against expectations, the clutch size of this species is decreasing even though metal emissions in the area have decreased considerably over the past two decades. Here, we document long-term population-level changes in the clutch size of P. major and explore if changes in population density, population numbers of competing species, timing of breeding, breeding habitat, or female age distribution can explain decreasing clutch sizes. Clutch size of P. major decreased by one egg in the polluted zone during the past 21 years, while there was no significant change in clutch size in the unpolluted reference zone over this time period. Density of P. major nests was similar in both environments but increased threefold during the study period in both areas (from 0.8 to 2.4 nest/ha). In the polluted zone, clutch size has decreased as a response to a considerable increase in population density, while a corresponding density change in the unpolluted zone did not have such an effect. The other factors studied did not explain the clutch size trend. Fledgling numbers in the polluted environment have been relatively low since the beginning of the study period, and they do not show a corresponding decrease to that noted for the clutch size over the same time period. Our study shows that responses of commonly measured life-history parameters to anthropogenic pollution depend on the structure of the breeding population. Interactions between pollution and intrinsic population characters should therefore be taken into account in environmental studies.

Re-creating missing population baselines for Pacific reef sharks.

PubMed

Nadon, Marc O; Baum, Julia K; Williams, Ivor D; McPherson, Jana M; Zgliczynski, Brian J; Richards, Benjamin L; Schroeder, Robert E; Brainard, Russell E

2012-06-01

Sharks and other large predators are scarce on most coral reefs, but studies of their historical ecology provide qualitative evidence that predators were once numerous in these ecosystems. Quantifying density of sharks in the absence of humans (baseline) is, however, hindered by a paucity of pertinent time-series data. Recently researchers have used underwater visual surveys, primarily of limited spatial extent or nonstandard design, to infer negative associations between reef shark abundance and human populations. We analyzed data from 1607 towed-diver surveys (>1 ha transects surveyed by observers towed behind a boat) conducted at 46 reefs in the central-western Pacific Ocean, reefs that included some of the world's most pristine coral reefs. Estimates of shark density from towed-diver surveys were substantially lower (<10%) than published estimates from surveys along small transects (<0.02 ha), which is not consistent with inverted biomass pyramids (predator biomass greater than prey biomass) reported by other researchers for pristine reefs. We examined the relation between the density of reef sharks observed in towed-diver surveys and human population in models that accounted for the influence of oceanic primary productivity, sea surface temperature, reef area, and reef physical complexity. We used these models to estimate the density of sharks in the absence of humans. Densities of gray reef sharks (Carcharhinus amblyrhynchos), whitetip reef sharks (Triaenodon obesus), and the group "all reef sharks" increased substantially as human population decreased and as primary productivity and minimum sea surface temperature (or reef area, which was highly correlated with temperature) increased. Simulated baseline densities of reef sharks under the absence of humans were 1.1-2.4/ha for the main Hawaiian Islands, 1.2-2.4/ha for inhabited islands of American Samoa, and 0.9-2.1/ha for inhabited islands in the Mariana Archipelago, which suggests that density of reef sharks has declined to 3-10% of baseline levels in these areas. ©2012 Society for Conservation Biology No claim to original US government works.

The frequency and distribution of recent landslides in three montane tropical regions of Puerto Rico

Treesearch

Matthew C. Larsen; Angel J. Torres-Sanchez

1998-01-01

Landslides are common in steep mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high. Each year, landslides cause extensive damage to property and occasionally result in loss of life. Average population density is high, 422 peoplerkm2, and is increasing. This increase in population density is accompanied by growing...

Extreme Environment Basing:Contingency Basing in Dense Urban and Megacity Environments

DTIC Science & Technology

2016-05-24

the placement of a U.S. military contingency base. As stated above, the consideration given to the volume of displaced people caused by the base camp...population density , Dhaka, Bangladesh ........................... 29 B-1 The base camp development planning process...urban areas are not incredibly dense, a great many are. These places represent the extreme end of the urban spectrum for population density and city

ECOLOGICAL DETERMINANTS OF AVIAN INFLUENZA VIRUS, WEST NILE VIRUS, AND AVIAN PARAMYXOVIRUS INFECTION AND ANTIBODY STATUS IN BLUE-WINGED TEAL (ANAS DISCORS) IN THE CANADIAN PRAIRIES.

PubMed

Nallar, Rodolfo; Papp, Zsuzsanna; Leighton, Frederick A; Epp, Tasha; Pasick, John; Berhane, Yohannes; Lindsay, Robbin; Soos, Catherine

2016-01-01

The Canadian prairies are one of the most important breeding and staging areas for migratory waterfowl in North America. Hundreds of thousands of waterfowl of numerous species from multiple flyways converge in and disperse from this region annually; therefore this region may be a key area for potential intra- and interspecific spread of infectious pathogens among migratory waterfowl in the Americas. Using Blue-winged Teal (Anas discors, BWTE), which have the most extensive migratory range among waterfowl species, we investigated ecologic risk factors for infection and antibody status to avian influenza virus (AIV), West Nile virus (WNV), and avian paramyxovirus-1 (APMV-1) in the three prairie provinces (Alberta, Saskatchewan, and Manitoba) prior to fall migration. We used generalized linear models to examine infection or evidence of exposure in relation to host (age, sex, body condition, exposure to other infections), spatiotemporal (year, province), population-level (local population densities of BWTE, total waterfowl densities), and environmental (local pond densities) factors. The probability of AIV infection in BWTE was associated with host factors (e.g., age and antibody status), population-level factors (e.g., local BWTE population density), and year. An interaction between age and AIV antibody status showed that hatch year birds with antibodies to AIV were more likely to be infected, suggesting an antibody response to an active infection. Infection with AIV was positively associated with local BWTE density, supporting the hypothesis of density-dependent transmission. The presence of antibodies to WNV and APMV-1 was positively associated with age and varied among years. Furthermore, the probability of being WNV antibody positive was positively associated with pond density rather than host population density, likely because ponds provide suitable breeding habitat for mosquitoes, the primary vectors for transmission. Our findings highlight the importance of spatiotemporal, environmental, and host factors at the individual and population levels, all of which may influence dynamics of these and other viruses in wild waterfowl populations.

Density-dependent natal dispersal patterns in a leopard population recovering from over-harvest.

PubMed

Fattebert, Julien; Balme, Guy; Dickerson, Tristan; Slotow, Rob; Hunter, Luke

2015-01-01

Natal dispersal enables population connectivity, gene flow and metapopulation dynamics. In polygynous mammals, dispersal is typically male-biased. Classically, the 'mate competition', 'resource competition' and 'resident fitness' hypotheses predict density-dependent dispersal patterns, while the 'inbreeding avoidance' hypothesis posits density-independent dispersal. In a leopard (Panthera pardus) population recovering from over-harvest, we investigated the effect of sex, population density and prey biomass, on age of natal dispersal, distance dispersed, probability of emigration and dispersal success. Over an 11-year period, we tracked 35 subadult leopards using VHF and GPS telemetry. Subadult leopards initiated dispersal at 13.6 ± 0.4 months. Age at commencement of dispersal was positively density-dependent. Although males (11.0 ± 2.5 km) generally dispersed further than females (2.7 ± 0.4 km), some males exhibited opportunistic philopatry when the population was below capacity. All 13 females were philopatric, while 12 of 22 males emigrated. Male dispersal distance and emigration probability followed a quadratic relationship with population density, whereas female dispersal distance was inversely density-dependent. Eight of 12 known-fate females and 5 of 12 known-fate male leopards were successful in settling. Dispersal success did not vary with population density, prey biomass, and for males, neither between dispersal strategies (philopatry vs. emigration). Females formed matrilineal kin clusters, supporting the resident fitness hypothesis. Conversely, mate competition appeared the main driver for male leopard dispersal. We demonstrate that dispersal patterns changed over time, i.e. as the leopard population density increased. We conclude that conservation interventions that facilitated local demographic recovery in the study area also restored dispersal patterns disrupted by unsustainable harvesting, and that this indirectly improved connectivity among leopard populations over a larger landscape.

Density-Dependent Natal Dispersal Patterns in a Leopard Population Recovering from Over-Harvest

PubMed Central

Fattebert, Julien; Balme, Guy; Dickerson, Tristan; Slotow, Rob; Hunter, Luke

2015-01-01

Natal dispersal enables population connectivity, gene flow and metapopulation dynamics. In polygynous mammals, dispersal is typically male-biased. Classically, the ‘mate competition’, ‘resource competition’ and ‘resident fitness’ hypotheses predict density-dependent dispersal patterns, while the ‘inbreeding avoidance’ hypothesis posits density-independent dispersal. In a leopard (Panthera pardus) population recovering from over-harvest, we investigated the effect of sex, population density and prey biomass, on age of natal dispersal, distance dispersed, probability of emigration and dispersal success. Over an 11-year period, we tracked 35 subadult leopards using VHF and GPS telemetry. Subadult leopards initiated dispersal at 13.6 ± 0.4 months. Age at commencement of dispersal was positively density-dependent. Although males (11.0 ± 2.5 km) generally dispersed further than females (2.7 ± 0.4 km), some males exhibited opportunistic philopatry when the population was below capacity. All 13 females were philopatric, while 12 of 22 males emigrated. Male dispersal distance and emigration probability followed a quadratic relationship with population density, whereas female dispersal distance was inversely density-dependent. Eight of 12 known-fate females and 5 of 12 known-fate male leopards were successful in settling. Dispersal success did not vary with population density, prey biomass, and for males, neither between dispersal strategies (philopatry vs. emigration). Females formed matrilineal kin clusters, supporting the resident fitness hypothesis. Conversely, mate competition appeared the main driver for male leopard dispersal. We demonstrate that dispersal patterns changed over time, i.e. as the leopard population density increased. We conclude that conservation interventions that facilitated local demographic recovery in the study area also restored dispersal patterns disrupted by unsustainable harvesting, and that this indirectly improved connectivity among leopard populations over a larger landscape. PMID:25875293

Density-dependent vulnerability of forest ecosystems to drought

USGS Publications Warehouse

Bottero, Alessandra; D'Amato, Anthony W.; Palik, Brian J.; Bradford, John B.; Fraver, Shawn; Battaglia, Mike A.; Asherin, Lance A.

2017-01-01

1. Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a given area, is a primary driver of competitive intensity among trees, which influences tree growth and mortality. Manipulating tree population density may be a mechanism for moderating drought-induced stress and growth reductions, although the relationship between tree population density and tree drought vulnerability remains poorly quantified, especially across climatic gradients.2. In this study, we examined three long-term forest ecosystem experiments in two widely distributed North American pine species, ponderosa pine Pinus ponderosa (Lawson & C. Lawson) and red pine Pinus resinosa (Aiton), to better elucidate the relationship between tree population density, growth and drought. These experiments span a broad latitude and aridity range and include tree population density treatments that have been purposefully maintained for several decades. We investigated how tree population density influenced resistance (growth during drought) and resilience (growth after drought compared to pre-drought growth) of stand-level growth during and after documented drought events.3. Our results show that relative tree population density was negatively related to drought resistance and resilience, indicating that trees growing at lower densities were less vulnerable to drought. This result was apparent in all three forest ecosystems, and was consistent across species, stand age and drought intensity.4. Synthesis and applications. Our results highlighted that managing pine forest ecosystems at low tree population density represents a promising adaptive strategy for reducing the adverse impacts of drought on forest growth in coming decades. Nonetheless, the broader applicability of our findings to other types of forest ecosystems merits additional investigation.

A spatial mark–resight model augmented with telemetry data

USGS Publications Warehouse

Sollmann, Rachel; Gardner, Beth; Parsons, Arielle W.; Stocking, Jessica J.; McClintock, Brett T.; Simons, Theodore R.; Pollock, Kenneth H.; O’Connell, Allan F.

2013-01-01

Abundance and population density are fundamental pieces of information for population ecology and species conservation, but they are difficult to estimate for rare and elusive species. Mark-resight models are popular for estimating population abundance because they are less invasive and expensive than traditional mark-recapture. However, density estimation using mark-resight is difficult because the area sampled must be explicitly defined, historically using ad-hoc approaches. We develop a spatial mark-resight model for estimating population density that combines spatial resighting data and telemetry data. Incorporating telemetry data allows us to inform model parameters related to movement and individual location. Our model also allows 2. The model presented here will have widespread utility in future applications, especially for species that are not naturally marked.

Population status of chimpanzees in the Masito-Ugalla Ecosystem, Tanzania.

PubMed

Piel, Alex K; Cohen, Naomi; Kamenya, Shadrack; Ndimuligo, Sood A; Pintea, Lilian; Stewart, Fiona A

2015-10-01

More than 75 percent of Tanzania's chimpanzees live at low densities on land outside national parks. Chimpanzees are one of the key conservation targets in the region and long-term monitoring of these populations is essential for assessing the overall status of ecosystem health and the success of implemented conservation strategies. We aimed to assess change in chimpanzee density within the Masito-Ugalla Ecosystem (MUE) by comparing results of re-walking the same line transects in 2007 and 2014. We further used published remote sensing data derived from Landsat satellites to assess forest cover change within a 5 km buffer of these transects over that same period. We detected no statistically significant decline in chimpanzee density across the surveyed areas of MUE between 2007 and 2014, although the overall mean density of chimpanzees declined from 0.09 individuals/km(2) in 2007 to 0.05 individuals/km(2) in 2014. Whether this change is biologically meaningful cannot be determined due to small sample sizes and large, entirely overlapping error margins. It is therefore possible that the MUE chimpanzee population has been stable over this period and indeed in some areas (Issa Valley, Mkanga, Kamkulu) even showed an increase in chimpanzee density. Variation in chimpanzee habitat preference for ranging or nesting could explain variation in density at some of the survey sites between 2007 and 2014. We also found a relationship between increasing habitat loss and lower mean chimpanzee density. Future surveys will need to ensure a larger sample size, broader geographic effort, and random survey design, to more precisely determine trends in MUE chimpanzee density and population size over time. © 2015 Wiley Periodicals, Inc.

Increased population density of neurosurgeons associated with decreased risk of death from motor vehicle accidents in the United States.

PubMed

Desai, Atman; Bekelis, Kimon; Zhao, Wenyan; Ball, Perry A

2012-09-01

Motor vehicle accidents (MVAs) are a leading cause of death and disability in young people. Given that a major cause of death from MVAs is traumatic brain injury, and neurosurgeons hold special expertise in this area relative to other members of a trauma team, the authors hypothesized that neurosurgeon population density would be related to reduced mortality from MVAs across US counties. The Area Resource File (2009-2010), a national health resource information database, was retrospectively analyzed. The primary outcome variable was the 3-year (2004-2006) average in MVA deaths per million population for each county. The primary independent variable was the density of neurosurgeons per million population in the year 2006. Multiple regression analysis was performed, adjusting for population density of general practitioners, urbanicity of the county, and socioeconomic status of the county. The median number of annual MVA deaths per million population, in the 3141 counties analyzed, was 226 (interquartile range [IQR] 151-323). The median number of neurosurgeons per million population was 0 (IQR 0-0), while the median number of general practitioners per million population was 274 (IQR 175-410). Using an unadjusted analysis, each increase of 1 neurosurgeon per million population was associated with 1.90 fewer MVA deaths per million population (p < 0.001). On multivariate adjusted analysis, each increase of 1 neurosurgeon per million population was associated with 1.01 fewer MVA deaths per million population (p < 0.001), with a respective decrease in MVA deaths of 0.03 per million population for an increase in 1 general practitioner (p = 0.007). Rural location, persistent poverty, and low educational level were all associated with significant increases in the rate of MVA deaths. A higher population density of neurosurgeons is associated with a significant reduction in deaths from MVAs, a major cause of death nationally. This suggests that the availability of local neurosurgeons is an important factor in the overall likelihood of survival from an MVA, and therefore indicates the importance of promoting neurosurgical education and practice throughout the country.

Temporal lobe epilepsy patients with severe hippocampal neuron loss but normal hippocampal volume: Extracellular matrix molecules are important for the maintenance of hippocampal volume.

PubMed

Peixoto-Santos, Jose Eduardo; Velasco, Tonicarlo Rodrigues; Galvis-Alonso, Orfa Yineth; Araujo, David; Kandratavicius, Ludmyla; Assirati, Joao Alberto; Carlotti, Carlos Gilberto; Scandiuzzi, Renata Caldo; Santos, Antonio Carlos dos; Leite, Joao Pereira

2015-10-01

Hippocampal sclerosis is a common finding in patients with temporal lobe epilepsy (TLE), and magnetic resonance imaging (MRI) studies associate the reduction of hippocampal volume with the neuron loss seen on histologic evaluation. Astrogliosis and increased levels of chondroitin sulfate, a major component of brain extracellular matrix, are also seen in hippocampal sclerosis. Our aim was to evaluate the association between hippocampal volume and chondroitin sulfate, as well as neuronal and astroglial populations in the hippocampus of patients with TLE. Patients with drug-resistant TLE were subdivided, according to hippocampal volume measured by MRI, into two groups: hippocampal atrophy (HA) or normal volume (NV) cases. Hippocampi from TLE patients and age-matched controls were submitted to immunohistochemistry to evaluate neuronal population, astroglial population, and chondroitin sulfate expression with antibodies against neuron nuclei protein (NeuN), glial fibrillary acidic protein (GFAP), and chondroitin sulfate (CS-56) antigens, respectively. Both TLE groups were clinically similar. NV cases had higher hippocampal volume, both ipsilateral and contralateral, when compared to HA. Compared to controls, NV and HA patients had reduced neuron density, and increased GFAP and CS-56 immunopositive area. There was no statistical difference between NV and HA groups in neuron density or immunopositive areas for GFAP and CS-56. Hippocampal volume correlated positively with neuron density in CA1 and prosubiculum, and with immunopositive areas for CS-56 in CA1, and negatively with immunopositive area for GFAP in CA1. Multiple linear regression analysis indicated that both neuron density and CS-56 immunopositive area in CA1 were statistically significant predictors of hippocampal volume. Our findings indicate that neuron density and chondroitin sulfate immunopositive area in the CA1 subfield are crucial for the hippocampal volume, and that chondroitin sulfate is important for the maintenance of a normal hippocampal volume in some cases with severe neuron loss. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Population, conservation, and land use change in Honduras

Treesearch

Max J. Pfeffer; John W. Schlelhas; Stephen D. DeGloria; Jorge Gomez

2005-01-01

This paper examines the role of population density on land use allocation and change. We are especially interested in the management of fallow areas that have come under increasing pressure given restrictions imposed by the creation of protected areas like national parks. It is argued that these restrictions to reduce deforestation create a relative scarcity of land,...

Density-dependent regulation of population size in colonial breeders: Allee and buffer effects in the migratory Montagu's harrier.

PubMed

Soutullo, Alvaro; Limiñana, Rubén; Urios, Vicente; Surroca, Martín; A Gill, Jennifer

2006-09-01

Expanding populations offer an opportunity to uncover the processes driving spatial variation in distribution and abundance. Individual settlement decisions will be influenced by the availability and relative quality of patches, and by how these respond to changes in conspecific density. For example, conspecific presence can alter patch suitability through reductions in resource availability or territorial exclusion, leading to buffer effect patterns of disproportionate population expansion into poorer quality areas. However, conspecific presence can also enhance patch suitability through Allee effect processes, such as transmission of information about resources or improved predator detection and deterrence. Here, we explore the factors underlying the settlement pattern of a growing population of Montagu's harriers (Circus pygargus) in Spain. The population increased exponentially between 1981 and 2001, but stabilised between 2001 and 2004. This population increase occurred alongside a remarkable spatial expansion, with novel site use occurring prior to maximum densities in occupied sites being reached. However, no temporal trends in fecundity were observed and, within sites, average fecundity did not decline with increasing density. Across the population, variance in productivity did increase with population size, suggesting a complex pattern of density-dependent costs and benefits. We suggest that both Allee and buffer effects are operating in this system, with the benefits of conspecific presence counteracting density-dependent declines in resource availability or quality.

Urban heat island effect on cicada densities in metropolitan Seoul.

PubMed

Nguyen, Hoa Q; Andersen, Desiree K; Kim, Yuseob; Jang, Yikweon

2018-01-01

Urban heat island (UHI) effect, the ubiquitous consequence of urbanization, is considered to play a major role in population expansion of numerous insects. Cryptotympana atrata and Hyalessa fuscata are the most abundant cicada species in the Korean Peninsula, where their population densities are higher in urban than in rural areas. We predicted a positive relationship between the UHI intensities and population densities of these two cicada species in metropolitan Seoul. To test this prediction, enumeration surveys of cicada exuviae densities were conducted in 36 localities located within and in the vicinity of metropolitan Seoul. Samples were collected in two consecutive periods from July to August 2015. The abundance of each species was estimated by two resource-weighted densities, one based on the total geographic area, and the other on the total number of trees. Multiple linear regression analyses were performed to identify factors critical for the prevalence of cicada species in the urban habitat. C. atrata and H. fuscata were major constituents of cicada species composition collected across all localities. Minimum temperature and sampling period were significant factors contributing to the variation in densities of both species, whereas other environmental factors related to urbanization were not significant. More cicada exuviae were collected in the second rather than in the first samplings, which matched the phenological pattern of cicadas in metropolitan Seoul. Cicada population densities increased measurably with the increase in temperature. Age of residential complex also exhibited a significantly positive correlation to H. fuscata densities, but not to C. atrata densities. Effects of temperature on cicada densities have been discerned from other environmental factors, as cicada densities increased measurably in tandem with elevated temperature. Several mechanisms may contribute to the abundance of cicadas in urban environments, such as higher fecundity of females, lower mortality rate of instars, decline in host plant quality, and local adaptation of organisms, but none of them were tested in the current study. In sum, results of the enumeration surveys of cicada exuviae support the hypothesis that the UHI effect underlies the population expansion of cicadas in metropolitan Seoul. Nevertheless, the underlying mechanisms for this remain untested.

Cannibalism in invasive, native and biocontrol populations of the harlequin ladybird.

PubMed

Tayeh, Ashraf; Estoup, Arnaud; Lombaert, Eric; Guillemaud, Thomas; Kirichenko, Natalia; Lawson-Handley, Lori; De Clercq, Patrick; Facon, Benoît

2014-02-05

Cannibalism is widespread in both vertebrates and invertebrates but its extent is variable between and within species. Cannibalism depends on population density and nutritional conditions, and could be beneficial during colonisation of new environments. Empirical studies are needed to determine whether this trait might facilitate invasion of a new area in natural systems. We investigated whether the propensity for cannibalism in H. axyridis differs both between native and invasive populations and between invasive populations from the core and from the front of the invasive area in Western Europe. We also compared the propensity for cannibalism of these natural populations with that of laboratory-reared biocontrol populations. We measured the cannibalism rates of eggs by first instar larvae and adult females at two different individual densities of ladybirds from three types of population (invasive, native and biocontrol), in laboratory-controlled conditions. Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations, but there was no difference in cannibalism rates between populations from the core or front of the invaded range. Cannibalism was significantly lower in larvae from biocontrol populations compared to wild (invasive and native) populations. No differences in cannibalism rates of adult females were found between any populations. While high population density significantly increased cannibalism in both larvae and adults, the norm of reaction of cannibalism to individual density did not change significantly during the invasion and/or laboratory rearing processes. This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones. Our experiments also shed light on the difference in cannibalism evolution with respect to life stages. However, we are still at an early stage in understanding the underlying mechanisms and several different research perspectives are needed to determine whether the higher propensity for cannibalism is a general feature of the invasion process.

Cannibalism in invasive, native and biocontrol populations of the harlequin ladybird

PubMed Central

2014-01-01

Background Cannibalism is widespread in both vertebrates and invertebrates but its extent is variable between and within species. Cannibalism depends on population density and nutritional conditions, and could be beneficial during colonisation of new environments. Empirical studies are needed to determine whether this trait might facilitate invasion of a new area in natural systems. We investigated whether the propensity for cannibalism in H. axyridis differs both between native and invasive populations and between invasive populations from the core and from the front of the invasive area in Western Europe. We also compared the propensity for cannibalism of these natural populations with that of laboratory-reared biocontrol populations. We measured the cannibalism rates of eggs by first instar larvae and adult females at two different individual densities of ladybirds from three types of population (invasive, native and biocontrol), in laboratory-controlled conditions. Results Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations, but there was no difference in cannibalism rates between populations from the core or front of the invaded range. Cannibalism was significantly lower in larvae from biocontrol populations compared to wild (invasive and native) populations. No differences in cannibalism rates of adult females were found between any populations. While high population density significantly increased cannibalism in both larvae and adults, the norm of reaction of cannibalism to individual density did not change significantly during the invasion and/or laboratory rearing processes. Conclusion This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones. Our experiments also shed light on the difference in cannibalism evolution with respect to life stages. However, we are still at an early stage in understanding the underlying mechanisms and several different research perspectives are needed to determine whether the higher propensity for cannibalism is a general feature of the invasion process. PMID:24495338

Evaluating potential conservation conflicts between two listed species: Sea otters and black abalone

USGS Publications Warehouse

Raimondi, Peter T.; Jurgens, Laura J.; Tinker, M. Tim

2015-01-01

Population consequences of endangered species interacting as predators and prey have been considered theoretically and legally, but rarely investigated in the field. We examined relationships between spatially variable populations of a predator, the California sea otter, Enhydra lutris nereis, and a prey species, the black abalone, Haliotis cracherodii. Both species are federally listed under the Endangered Species Act and co-occur along the coast of California. We compared the local abundance and habitat distribution of black abalone at 12 sites with varying densities of sea otters. All of the populations of abalone we examined were in the geographic area currently unaffected by withering disease, which has decimated populations south of the study area. Surprisingly, our findings indicate that sea otter density is positively associated with increased black abalone density. The presence of sea otters also correlated with a shift in black abalone to habitat conferring greater refuge, which could decrease illegal human harvest. These results highlight the need for a multi-species approach to conservation management of the two species, and demonstrate the importance of using field-collected data rather than simple trophic assumptions to understand relationships between jointly vulnerable predator and prey populations.

Evaluating potential conservation conflicts between two listed species: sea otters and black abalone.

PubMed

Raimondi, Peter; Jurgens, Laura J; Tinker, M Tim

2015-11-01

Population consequences of endangered species interacting as predators and prey have been considered theoretically and legally, but rarely investigated in the field. We examined relationships between spatially variable populations of a predator, the California sea otter, Enhydra lutris nereis, and a prey species, the black abalone, Haliotis cracherodii. Both species are federally listed under the Endangered Species Act and co-occur along the coast of California. We compared the local abundance and habitat distribution of black abalone at 12 sites with varying densities of sea otters. All of the populations of abalone we examined were in the geographic area currently unaffected by withering disease, which has decimated populations south of the study area. Surprisingly, our findings indicate that sea otter density is positively associated with increased black abalone density. The presence of sea otters also correlated with a shift in black abalone to habitat conferring greater refuge, which could decrease illegal human harvest. These results highlight the need for a multi-species approach to conservation management of the two species, and demonstrate the importance of using field-collected data rather than simple trophic assumptions to understand relationships between jointly vulnerable predator and prey populations.

Population dynamics, structure and behavior of Anopheles darlingi in a rural settlement in the Amazon rainforest of Acre, Brazil.

PubMed

Moutinho, Paulo Rufalco; Gil, Luis Herman Soares; Cruz, Rafael Bastos; Ribolla, Paulo Eduardo Martins

2011-06-24

Anopheles darlingi is the major vector of malaria in South America, and its behavior and distribution has epidemiological importance to biomedical research. In Brazil, An. darlingi is found in the northern area of the Amazon basin, where 99.5% of the disease is reported. The study area, known as Ramal do Granada, is a rural settlement inside the Amazon basin in the state of Acre. Population variations and density have been analysed by species behaviour, and molecular analysis has been measured by ND4 mitochondrial gene sequencing. The results show higher density in collections near a recent settlement, suggesting that a high level of colonization decreases the vector presence. The biting activity showed higher activity at twilight and major numbers of mosquitos in the remaining hours of the night in months of high density. From a sample of 110 individual mosquitoes, 18 different haplotypes were presented with a diversity index of 0.895, which is higher than that found in other Anopheles studies. An. darlingi depends on forested regions for their larval and adult survival. In months with higher population density, the presence of mosquitoes persisted in the second part of the night, increasing the vector capacity of the species. Despite the intra-population variation in the transition to rainy season, the seasonal distribution of haplotypes shows no change in the structure population of An. darlingi.

A Comparison of the Human Buccal Cell Assay and the Pollen Abortion Assay in Assessing Genotoxicity in an Urban-Rural Gradient

PubMed Central

Fleck, Alan da Silveira; Vieira, Mariana; Amantéa, Sergio Luís; Rhoden, Claudia Ramos

2014-01-01

Air pollution is exacerbated near heavy traffic roads in cities. Air pollution concentration and composition vary by region and depend on urban-rural gradients. The aim of this study was to evaluate the distribution of air pollution in areas of varying population densities and to compare plant biomonitoring with an established biomarker of human exposure to traffic-related air pollution in children. The areas of study were selected near a major street in 3 different regions. Areas A, B and C represent high, intermediate and low population densities, respectively. Micronucleus assay, an established biomarker of human exposure, was performed in children from these areas. For a plant biomonitoring assay, the pollen abortion assay was performed on Bauhinia variegata in these areas. NO2 and O3 concentrations were determined by passive sampling. We report here that the pollen abortion frequency in Bauhinia variegata is correlated with NO2 concentration (P = 0.004) and is strongly associated with vehicular flow and population density in the studied areas. Micronuclei frequency in buccal cells of children was higher in the regions with more degree of urbanization (P < 0.001) following the same pattern of O3 concentrations (P = 0.030). In conclusion, our results demonstrate that high concentrations of air pollutants in Porto Alegre are related to both human and plant genotoxicity. Areas with different concentration of pollutants demonstrated to have an urbanization gradient dependent pattern which also reflected on genotoxic damage among these areas. PMID:25166920

Occupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape

USGS Publications Warehouse

Hill, Jason M.; Diefenbach, Duane R.

2014-01-01

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single-season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter–area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m2. Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter–area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland ( = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the foreseeable future.

Land Use, Residential Density, and Walking

PubMed Central

Rodríguez, Daniel A.; Evenson, Kelly R.; Diez Roux, Ana V.; Brines, Shannon J.

2009-01-01

Background The neighborhood environment may play a role in encouraging sedentary patterns, especially for middle-aged and older adults. Purpose Associations between walking and neighborhood population density, retail availability, and land use distribution were examined using data from a cohort of adults aged 45 to 84 years old. Methods Data from a multi-ethnic sample of 5529 adult residents of Baltimore MD, Chicago IL, Forsyth County NC, Los Angeles CA, New York NY, and St. Paul MN, enrolled in the Multi-Ethnic Study of Atherosclerosis in 2000–2002 were linked to secondary land use and population data. Participant reports of access to destinations and stores and objective measures of the percentage of land area in parcels devoted to retail land uses, the population divided by land area in parcels, and the mixture of uses for areas within 200m of each participant's residence were examined. Multinomial logistic regression was used to investigate associations of self-reported and objective neighborhood characteristics with walking. All analyses were conducted in 2008 and 2009. Results After adjustment for individual-level characteristics and neighborhood connectivity, higher density, greater land area devoted to retail uses, and self-reported measures of proximity of destinations and ease of walking to places were each related to walking. In models including all land use measures, population density was positively associated with walking to places and with walking for exercise for more than 90 min/wk both relative to no walking. Availability of retail was associated with walking to places relative to not walking, having a more proportional mix of land uses was associated with walking for exercise for more than 90 min/wk, while self-reported ease of access to places was related to higher levels of exercise walking both relative to not walking. Conclusions Residential density and the presence of retail uses are related to various walking behaviors. Efforts to increase walking may benefit from attention to the intensity and type of land development. PMID:19840694

Land use, residential density, and walking. The multi-ethnic study of atherosclerosis.

PubMed

Rodríguez, Daniel A; Evenson, Kelly R; Diez Roux, Ana V; Brines, Shannon J

2009-11-01

The neighborhood environment may play a role in encouraging sedentary patterns, especially for middle-aged and older adults. The aim of this study was to examine the associations between walking and neighborhood population density, retail availability, and land-use distribution using data from a cohort of adults aged 45 to 84 years. Data from a multi-ethnic sample of 5529 adult residents of Baltimore MD, Chicago IL, Forsyth County NC, Los Angeles CA, New York NY, and St. Paul MN enrolled in the Multi-Ethnic Study of Atherosclerosis in 2000-2002 were linked to secondary land-use and population data. Participant reports of access to destinations and stores and objective measures of the percentage of land area in parcels devoted to retail land uses, the population divided by land area in parcels, and the mixture of uses for areas within 200 m of each participant's residence were examined. Multinomial logistic regression was used to investigate associations of self-reported and objective neighborhood characteristics with walking. All analyses were conducted in 2008 and 2009. After adjustment for individual-level characteristics and neighborhood connectivity, it was found that higher density, greater land area devoted to retail uses, and self-reported proximity of destinations and ease of walking to places were each related to walking. In models including all land-use measures, population density was positively associated with walking to places and with walking for exercise for more than 90 minutes/week, both relative to no walking. Availability of retail was associated with walking to places relative to not walking, and having a more proportional mix of land uses was associated with walking for exercise for more than 90 minutes/week, while self-reported ease of access to places was related to higher levels of exercise walking, both relative to not walking. Residential density and the presence of retail uses are related to various walking behaviors. Efforts to increase walking may benefit from attention to the intensity and type of land development.

Importance of latrine communication in European rabbits shifts along a rural-to-urban gradient.

PubMed

Ziege, Madlen; Bierbach, David; Bischoff, Svenja; Brandt, Anna-Lena; Brix, Mareike; Greshake, Bastian; Merker, Stefan; Wenninger, Sandra; Wronski, Torsten; Plath, Martin

2016-06-14

Information transfer in mammalian communication networks is often based on the deposition of excreta in latrines. Depending on the intended receiver(s), latrines are either formed at territorial boundaries (between-group communication) or in core areas of home ranges (within-group communication). The relative importance of both types of marking behavior should depend, amongst other factors, on population densities and social group sizes, which tend to differ between urban and rural wildlife populations. Our study is the first to assess (direct and indirect) anthropogenic influences on mammalian latrine-based communication networks along a rural-to-urban gradient in European rabbits (Oryctolagus cuniculus) living in urban, suburban and rural areas in and around Frankfurt am Main (Germany). The proportion of latrines located in close proximity to the burrow was higher at rural study sites compared to urban and suburban ones. At rural sites, we found the largest latrines and highest latrine densities close to the burrow, suggesting that core marking prevailed. By contrast, latrine dimensions and densities increased with increasing distance from the burrow in urban and suburban populations, suggesting a higher importance of peripheral marking. Increased population densities, but smaller social group sizes in urban rabbit populations may lead to an increased importance of between-group communication and thus, favor peripheral over core marking. Our study provides novel insights into the manifold ways by which man-made habitat alterations along a rural-to-urban gradient directly and indirectly affect wildlife populations, including latrine-based communication networks.

Hypsographic demography: The distribution of human population by altitude

PubMed Central

Cohen, Joel E.; Small, Christopher

1998-01-01

The global distribution of the human population by elevation is quantified here. As of 1994, an estimated 1.88 × 109 people, or 33.5% of the world’s population, lived within 100 vertical meters of sea level, but only 15.6% of all inhabited land lies below 100 m elevation. The median person lived at an elevation of 194 m above sea level. Numbers of people decreased faster than exponentially with increasing elevation. The integrated population density (IPD, the number of people divided by the land area) within 100 vertical meters of sea level was significantly larger than that of any other range of elevations and represented far more people. A significant percentage of the low-elevation population lived at moderate population densities rather than at the highest densities of central large cities. Assessments of coastal hazards that focus only on large cities may substantially underestimate the number of people who could be affected. PMID:9826643

An ecology of prestige in New York City: Examining the relationships among population density, socio-economic status, group identity, and residential canopy cover

Treesearch

J. Morgan Grove; Dexter H. Locke; Jarlath P.M. O' Neil-Dunne

2014-01-01

Several social theories have been proposed to explain the uneven distribution of vegetation in urban residential areas: population density, social stratification, luxury effect, and ecology of prestige. We evaluate these theories using a combination of demographic and socio-economic predictors of vegetative cover on all residential lands in New York City. We use...

Capture-recapture of white-tailed deer using DNA from fecal pellet-groups

USGS Publications Warehouse

Goode, Matthew J; Beaver, Jared T; Muller, Lisa I; Clark, Joseph D.; van Manen, Frank T.; Harper, Craig T; Basinger, P Seth

2014-01-01

Traditional methods for estimating white-tailed deer population size and density are affected by behavioral biases, poor detection in densely forested areas, and invalid techniques for estimating effective trapping area. We evaluated a noninvasive method of capture—recapture for white-tailed deer (Odocoileus virginianus) density estimation using DNA extracted from fecal pellets as an individual marker and for gender determination, coupled with a spatial detection function to estimate density (spatially explicit capture—recapture, SECR). We collected pellet groups from 11 to 22 January 2010 at randomly selected sites within a 1-km2 area located on Arnold Air Force Base in Coffee and Franklin counties, Tennessee. We searched 703 10-m radius plots and collected 352 pellet-group samples from 197 plots over five two-day sampling intervals. Using only the freshest pellets we recorded 140 captures of 33 different animals (15M:18F). Male and female densities were 1.9 (SE = 0.8) and 3.8 (SE = 1.3) deer km-2, or a total density of 5.8 deer km-2 (14.9 deer mile-2). Population size was 20.8 (SE = 7.6) over a 360-ha area, and sex ratio was 1.0 M: 2.0 F (SE = 0.71). We found DNA sampling from pellet groups improved deer abundance, density and sex ratio estimates in contiguous landscapes which could be used to track responses to harvest or other management actions.

Modelling drivers and distribution of lead and zinc concentrations in soils of an urban catchment (Sydney estuary, Australia).

PubMed

Johnson, L E; Bishop, T F A; Birch, G F

2017-11-15

The human population is increasing globally and land use is changing to accommodate for this growth. Soils within urban areas require closer attention as the higher population density increases the chance of human exposure to urban contaminants. One such example of an urban area undergoing an increase in population density is Sydney, Australia. The city also possesses a notable history of intense industrial activity. By integrating multiple soil surveys and covariates into a linear mixed model, it was possible to determine the main drivers and map the distribution of lead and zinc concentrations within the Sydney estuary catchment. The main drivers as derived from the model included elevation, distance to main roads, main road type, soil landscape, population density (lead only) and land use (zinc only). Lead concentrations predicted using the model exceeded the established guideline value of 300mgkg -1 over a large portion of the study area with concentrations exceeding 1000mgkg -1 in the south of the catchment. Predicted zinc did not exceed the established guideline value of 7400mgkg -1 ; however concentrations were higher to the south and west of the study area. Unlike many other studies we considered the prediction uncertainty when assessing the contamination risk. Although the predictions indicate contamination over a large area, the broadness of the prediction intervals suggests that in many of these areas we cannot be sure that the site is contaminated. More samples are required to determine the contaminant distribution with greater precision, especially in residential areas where contamination was highest. Managing sources and addressing areas of elevated lead and zinc concentrations in urban areas has the potential to reduce the impact of past human activities and improve the urban environment of the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Theoretical Approaches in the Context of Spatial Planning Decisions and the Relation with Urban Sustainability

NASA Astrophysics Data System (ADS)

Kumlu, Kadriye Burcu Yavuz; Tüdeş, Şule

2017-10-01

The sustainability agenda has maintained its importance since the days, when the production system took its capitalist form, as well as the population in the urban areas started to rise. Increasing number of both goods and the people have caused the degradation of the certain systems, which generate the urban areas. These systems could mainly be classified as social, environmental, physical and economical systems. Today, urban areas still have difficulty to protect those systems, due to the significant demand of the population. Therefore, studies related with the sustainable issues are significant in the sense of continuity of the urban systems. Therefore, in this paper, those studies in the context of the effects of physical decisions taken in the spatial planning process on urban sustainability, will be examined. The components of the physical decisions are limited to land use, density and design. Land use decisions will be examined in the context of mixed land use. On the other hand, decisions related with density will be analyzed in the sense of population density and floor area ratio (FAR). Besides, design decisions will be examined, by linking them with neighborhood design criteria. Additionally, the term of urban sustainability will only be limited to its social and environmental contexts in this study. Briefly stated, studies in the sustainable literature concerned with the effects of land use, density and design decisions taken in the spatial planning process on the social and environmental sustainability will be examined in this paper. After the compilation and the analyze of those studies, a theoretical approach will be proposed to determine social and environmental sustainability in the context of land use, density and design decisions, taken in the spatial planning process.

Derivation of Nationally Consistent Indices Representing Urban Intensity Within and Across Nine Metropolitan Areas of the Conterminous United States

USGS Publications Warehouse

Cuffney, Thomas F.; Falcone, James A.

2009-01-01

Two nationally consistent multimetric indices of urban intensity were developed to support studies of the effects of urbanization on streams in nine metropolitan areas of the conterminous United States: Atlanta, Georgia; Birmingham, Alabama; Boston, Massachusetts; Dallas-Fort Worth, Texas; Denver, Colorado; Milwaukee-Green Bay, Wisconsin; Portland, Oregon; Raleigh, North Carolina; and Salt Lake City, Utah. These studies were conducted as a part of the U.S. Geological Survey's National Water-Quality Assessment Program. These urban intensity indices were used to define gradients of urbanization and to interpret biological, physical, and chemical changes along these gradients. Ninety census, land-cover, and infrastructure variables obtained from nationally available databases were evaluated. Only variables that exhibited a strong and consistent linear relation with 2000 population density were considered for use in the indices. Housing-unit density (HUDEN), percentage of basin area in developed land (P_NLCD1_2), and road density (ROADDEN) were selected as the best representatives of census, land-cover, and infrastructure variables. The metropolitan area national urban intensity index (MA-NUII) was scaled to represent urban intensity within each metropolitan area and ranged from 0 (little or no urban) to 100 (maximum urban) for sites within each metropolitan area. The national urban intensity index (NUII) was scaled to represent urban intensity across all nine metropolitan areas and ranged from 0 to 100 for all sites. The rates at which HUDEN, P_NLCD1_2, and ROADDEN changed with changes in population density varied among metropolitan areas. Therefore, these variables were adjusted to obtain a more uniform rate of response across metropolitan areas in the derivation of the NUII. The NUII indicated that maximum levels of urban intensity occurred in the West and Midwest rather than in the East primarily because small inner-city streams in eastern metropolitan areas are buried and converted to storm drains or sewers and because of higher density development in the Western and Central United States. The national indices (MA-NUII, NUII) were compared to indices that were derived independently for each metropolitan area (MA-UII) based on variables that were of local interest. The MA-UIIs, which were based on 5 to 40 variables, tended to overestimate urban intensity relative to the national indices particularly when the MA-UII was composed of large numbers of variables that were not linearly related to population density as in Denver, Dallas-Fort Worth, and Milwaukee-Green Bay.

Influences of population size and density on birthplace effects.

PubMed

Hancock, David J; Coutinho, Patrícia; Côté, Jean; Mesquita, Isabel

2018-01-01

Contextual influences on talent development (e.g., birthplace effects) have become a topic of interest for sport scientists. Birthplace effects occur when being born in a certain city size leads to participation or performance advantages, typically for those born in smaller or mid-sized cities. The purpose of this study was to investigate birthplace effects in Portuguese volleyball players by analysing city size, as well as population density - an important but infrequently used variable. Participants included 4062 volleyball players (M age  = 33), 53.2% of whom were men. Using Portuguese national census data from 1981, we compared participants (within each sex) across five population categories. In addition, we used ANOVAs to study expertise and population density. Results indicated that men and women athletes born in districts of 200,000-399,999 were 2.4 times more likely to attain elite volleyball status, while all other districts decreased the odds of expert development. For men, being born in high-density areas resulted in less chance of achieving expertise, whereas there were no differences for women. The results suggest that athletes' infrastructure and social structure play an important role in talent development, and that these structures are influenced by total population and population density, respectively.

Arbuscular mycorrhizal mediation of biomass-density relationship of Medicago sativa L. under two water conditions in a field experiment.

PubMed

Zhang, Qian; Xu, Liming; Tang, Jianjun; Bai, Minge; Chen, Xin

2011-05-01

The biomass-density relationship (whereby the biomass of individual plants decreases as plant density increases) has generally been explained by competition for resources. Arbuscular mycorrhizal fungi (AMF) are able to affect plant interactions by mediating resource utilization, but whether this AMF-mediated interaction will change the biomass-density relationship is unclear. We conducted an experiment to test the hypothesis that AMF will shift the biomass-density relationship by affecting intraspecific competition. Four population densities (10, 100, 1,000, or 10,000 seedlings per square meter) of Medicago sativa L. were planted in field plots. Water application (1,435 or 327.7 mm/year) simulated precipitation in wet areas (sufficient water) and arid areas (insufficient water). The fungicide benomyl was applied to suppress AMF in some plots ("low-AMF" treatment) and not in others ("high-AMF" treatment). The effect of the AMF treatment on the biomass-density relationship depended on water conditions. High AMF enhanced the decrease of individual biomass with increasing density (the biomass-density line had a steeper slope) when water was sufficient but not when water was insufficient. AMF treatment did not affect plant survival rate or population size but did affect absolute competition intensity (ACI). When water was sufficient, ACI was significantly higher in the high-AMF treatment than in the low-AMF treatment, but ACI was unaffected by AMF treatment when water was insufficient. Our results suggest that AMF status did not impact survival rate and population size but did shift the biomass-density relationship via effects on intraspecific competition. This effect of AMF on the biomass-density relationship depended on the availability of water.

Factors Controlling Vegetation Fires in Protected and Non-Protected Areas of Myanmar

PubMed Central

Biswas, Sumalika; Vadrevu, Krishna Prasad; Lwin, Zin Mar; Lasko, Kristofer; Justice, Christopher O.

2015-01-01

Fire is an important disturbance agent in Myanmar impacting several ecosystems. In this study, we quantify the factors impacting vegetation fires in protected and non-protected areas of Myanmar. Satellite datasets in conjunction with biophysical and anthropogenic factors were used in a spatial framework to map the causative factors of fires. Specifically, we used the frequency ratio method to assess the contribution of each causative factor to overall fire susceptibility at a 1km scale. Results suggested the mean fire density in non-protected areas was two times higher than the protected areas. Fire-land cover partition analysis suggested dominant fire occurrences in the savannas (protected areas) and woody savannas (non-protected areas). The five major fire causative factors in protected areas in descending order include population density, land cover, tree cover percent, travel time from nearest city and temperature. In contrast, the causative factors in non-protected areas were population density, tree cover percent, travel time from nearest city, temperature and elevation. The fire susceptibility analysis showed distinct spatial patterns with central Myanmar as a hot spot of vegetation fires. Results from propensity score matching suggested that forests within protected areas have 11% less fires than non-protected areas. Overall, our results identify important causative factors of fire useful to address broad scale fire risk concerns at a landscape scale in Myanmar. PMID:25909632

Factors controlling vegetation fires in protected and non-protected areas of myanmar.

PubMed

Biswas, Sumalika; Vadrevu, Krishna Prasad; Lwin, Zin Mar; Lasko, Kristofer; Justice, Christopher O

2015-01-01

Fire is an important disturbance agent in Myanmar impacting several ecosystems. In this study, we quantify the factors impacting vegetation fires in protected and non-protected areas of Myanmar. Satellite datasets in conjunction with biophysical and anthropogenic factors were used in a spatial framework to map the causative factors of fires. Specifically, we used the frequency ratio method to assess the contribution of each causative factor to overall fire susceptibility at a 1km scale. Results suggested the mean fire density in non-protected areas was two times higher than the protected areas. Fire-land cover partition analysis suggested dominant fire occurrences in the savannas (protected areas) and woody savannas (non-protected areas). The five major fire causative factors in protected areas in descending order include population density, land cover, tree cover percent, travel time from nearest city and temperature. In contrast, the causative factors in non-protected areas were population density, tree cover percent, travel time from nearest city, temperature and elevation. The fire susceptibility analysis showed distinct spatial patterns with central Myanmar as a hot spot of vegetation fires. Results from propensity score matching suggested that forests within protected areas have 11% less fires than non-protected areas. Overall, our results identify important causative factors of fire useful to address broad scale fire risk concerns at a landscape scale in Myanmar.

Testicular oocytes in smallmouth bass in northeastern Minnesota in relation to varying levels of human activity.

PubMed

Kadlec, Sarah M; Johnson, Rodney D; Mount, David R; Olker, Jennifer H; Borkholder, Brian D; Schoff, Patrick K

2017-12-01

Testicular oocytes (TOs) have been found in black bass (Micropterus spp.) from many locations in North America. The presence of TOs is often assumed to imply exposure to estrogenic endocrine disrupting compounds (EDCs); however, a definitive causal relationship has yet to be established, and TO prevalence is not consistently low in fish from areas lacking evident EDC sources. This might indicate any of a number of situations: 1) unknown or unidentified EDCs or EDC sources, 2) induction of TOs by other stressors, or 3) testicular oocytes occurring spontaneously during normal development. In the present study, we analyzed TO occurrence in smallmouth bass (Micropterus dolomieu) from 8 populations in northeastern Minnesota watersheds with differing degrees of human development and, hence, presumed likelihood of exposure to anthropogenic chemicals. Three watersheds were categorized as moderately developed, based on the presence of municipal wastewater discharges and higher human population density (4-81 per km 2 ), and 5 watersheds were minimally developed, with very low human population density (0-1 per km 2 ) and minimal built environment. Testicular tissues from mature fish were evaluated using a semiquantitative method that estimated TO density, normalized by cross-sectional area. Testicular oocyte prevalence and density among populations from moderately developed watersheds was higher than in populations from minimally developed watersheds. However, TO prevalence was unexpectedly high and variable (7-43%) in some populations from minimally developed watersheds, and only weak evidence was found for a relationship between TO density and watershed development, suggesting alternative or more complex explanations for TO presence in smallmouth bass from this region. Environ Toxicol Chem 2017;36:3424-3435. © 2017 SETAC. © 2017 SETAC.

A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology.

PubMed

Tompkins, Adrian M; Ermert, Volker

2013-02-18

The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.

A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology

PubMed Central

2013-01-01

Background The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. Methods A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Results Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. Conclusions A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions. PMID:23419192

Sex differences in fingerprint ridge density in the Mataco-Mataguayo population.

PubMed

Gutiérrez-Redomero, E; Alonso, M C; Dipierri, J E

2011-12-01

Ridge density (RD), the number of digital ridges per unit area, varies according to sex, age, and population origin. The main objective of this study was to determine the extent of sexual dimorphism in RD and to set the age at which it appears, in an Amerindian sample from the Mataco-Mataguayo population. The sample studied for this research consisted of 99 males and 110 females, between 6 and 25 years old, which amounts to a total of 2090 fingerprints. Ridge count was carried out on distal radial and distal ulnar and on proximal regions of each finger to explore the RD patterns in order to identify similarities and differences among samples, areas, age groups, and sexes. RD decreased with age and, at all ages, RD was higher on the distal (radial and ulnar) areas, followed by the proximal sides. Females were found to have higher RD than males when older than 12 years, but not when younger. In the radial area, the Mataco-Mataguayo population, in both sexes, presented the RD similar to Spanish samples, but higher than all other populations analysed to date using this method. Variations in RD in the Amerindian population based on sex, age, and topology were confirmed in this work, and it is postulated that these variations are due to developmental differences among individuals and populations. A comparison between the Mataco-Mataguayo and Spanish populations is presented. Copyright © 2011 Elsevier GmbH. All rights reserved.

Black bear density in Glacier National Park, Montana

USGS Publications Warehouse

Stetz, Jeff B.; Kendall, Katherine C.; Macleod, Amy C.

2013-01-01

We report the first abundance and density estimates for American black bears (Ursus americanus) in Glacier National Park (NP),Montana, USA.We used data from 2 independent and concurrent noninvasive genetic sampling methods—hair traps and bear rubs—collected during 2004 to generate individual black bear encounter histories for use in closed population mark–recapture models. We improved the precision of our abundance estimate by using noninvasive genetic detection events to develop individual-level covariates of sampling effort within the full and one-half mean maximum distance moved (MMDM) from each bear’s estimated activity center to explain capture probability heterogeneity and inform our estimate of the effective sampling area.Models including the one-halfMMDMcovariate received overwhelming Akaike’s Information Criterion support suggesting that buffering our study area by this distance would be more appropriate than no buffer or the full MMDM buffer for estimating the effectively sampled area and thereby density. Our modelaveraged super-population abundance estimate was 603 (95% CI¼522–684) black bears for Glacier NP. Our black bear density estimate (11.4 bears/100 km2, 95% CI¼9.9–13.0) was consistent with published estimates for populations that are sympatric with grizzly bears (U. arctos) and without access to spawning salmonids. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Race, ethnicity, and noxious facilities: Environmental racism re- examined

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nieves, A.L.; Nieves, L.A.

1992-10-01

The charge has been made that hazardous facilities tend to be located in proximity to minority populations. This study uses a facility density measure for three categories of noxious facilities to examine the relationship between facilities and minority population concentrations. County-level data are used in a correlation analysis for African Americans, Hispanics, and Asians in the four major regions of the US. Even controlling for income and housing value, and limiting the data set to urban areas, consistent patterns of moderate to strong association of facility densities with minority population percentages are found.

42 CFR 414.410 - Phased-in implementation of competitive bidding programs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... largest MSAs by total population based on 2009 population estimates, and not already phased in as of June 1, 2008). CMS may subdivide any of the 91 MSAs with a population of greater than 8,000,000 into... population of less than 250,000. (iii) An area with low population density within an MSA not selected under...

42 CFR 414.410 - Phased-in implementation of competitive bidding programs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... largest MSAs by total population based on 2009 population estimates, and not already phased in as of June 1, 2008). CMS may subdivide any of the 91 MSAs with a population of greater than 8,000,000 into... population of less than 250,000. (iii) An area with low population density within an MSA not selected under...

42 CFR 414.410 - Phased-in implementation of competitive bidding programs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... largest MSAs by total population based on 2009 population estimates, and not already phased in as of June 1, 2008). CMS may subdivide any of the 91 MSAs with a population of greater than 8,000,000 into... population of less than 250,000. (iii) An area with low population density within an MSA not selected under...

Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus)

USDA-ARS?s Scientific Manuscript database

Thirteen red deer, culled from the isolated population at the Mongstad Oil Refinery, were investigated for gastrointestinal helminths. These animals, enclosed by the refinery fence, do not have contact with other ruminants and have a high population density considering the available browsing area (1...

Using Population Density and Size Class Frequency to Identify Recruitment Limitation and Saturation in Shellfishes

NASA Astrophysics Data System (ADS)

Bennett, B.

2016-02-01

Many fisheries are threatened due to overfishing, changing climate, and anthropogenic activities. Benthic marine organisms can be especially vulnerable to these pressures because of their inability to flee, and some of these organisms comprise the most threatened fisheries. Providing predictive tools to managers is key to reestablishing populations and sustainability in threatened or crashed fisheries. Here we examine the demographics of Cellana spp., culturally and culinarily important intertidal shellfishes in Hawai'i, in populations that are naturally recruitment limited and those that are recruitment saturated. We focus on variation in two demographic parameters: population density and size class frequency. From 2009 to 2015, yearly transect surveys were conducted on four isolated and uninhabited islands within the Papahānaumokuākea Marine National Monument (PMNM), a massive marine protected area. Two islands exhibit classic signs of recruitment limitation with several absent intertidal species and low population densities while two larger islands have a relative abundance of species and high population densities. The population density of C. exarata in the recruitment-saturated populations exhibit much higher variability, than in the recruitment-limited populations, that is driven by a massive recruitment peak in May-June. An inverted age pyramid characterized the recruitment-limited populations, which display a more stable adult-dominated population. The recruitment-saturated populations were characterized by a traditional age pyramid, which exhibit a less stable juvenile-dominated population. These results are being used to model and predict population dynamics in the intensely harvested populations of the main Hawaiian Islands for the purposes of management decision-making.

Effective Ice Particle Densities for Cold Anvil Cirrus

NASA Technical Reports Server (NTRS)

Heymsfield, Andrew J.; Schmitt, Carl G.; Bansemer, Aaron; Baumgardner, Darrel; Weinstock, Elliot M.; Smith, Jessica

2002-01-01

This study derives effective ice particle densities from data collected from the NASA WB-57F aircraft near the tops of anvils during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) in southern Florida in July 2002. The effective density, defined as the ice particle mass divided by the volume of an equivalent diameter liquid sphere, is obtained for particle populations and single sizes containing mixed particle habits using measurements of condensed water content and particle size distributions. The mean effective densities for populations decrease with increasing slopes of the gamma size distributions fitted to the size distributions. The population-mean densities range from near 0.91 g/cu m to 0.15 g/cu m. Effective densities for single sizes obey a power-law with an exponent of about -0.55, somewhat less steep than found from earlier studies. Our interpretations apply to samples where particle sizes are generally below 200-300 microns in maximum dimension because of probe limitations.

Population cycles in small rodents.

PubMed

Krebs, C J; Gaines, M S; Keller, B L; Myers, J H; Tamarin, R H

1973-01-05

We conclude that population fluctuations in Microtus in southern Indiana are produced by a syndrome of changes in birth and death rates similar to that found in other species of voles and lemmings. The mechanisms which cause the changes in birth and death rates are demolished by fencing the population so that no dispersal can occur. Dispersal thus seems critical for population regulation in Microtus. Because most dispersal occurs during the increase phase of the population cycle and there is little dispersal during the decline phase, dispersal is not directly related to population density. Hence the quality of dispersing animals must be important, and we have found one case of increased dispersal tendency by one genotype. The failure of population regulation of Microtus in enclosed areas requires an explanation by any hypothesis attempting to explain population cycles in small rodents. It might be suggested that the fence changed the predation pressure on the enclosed populations. However, the fence was only 2 feet (0.6 meter) high and did not stop the entrance of foxes, weasels, shrews, or avian predators. A striking feature was that the habitat in the enclosures quickly recovered from complete devastation by the start of the spring growing season. Obviously the habitat and food quality were sufficient to support Microtus populations of abnormally high densities, and recovery of the habitat was sufficiently quick that the introduction of new animals to these enclosed areas resulted in another population explosion. Finally, hypotheses of population regulation by social stress must account for the finding that Microtus can exist at densities several times greater than normal without "stress" taking an obvious toll. We hypothesize that the prevention of dispersal changes the quality of the populations in the enclosures in comparison to those outside the fence. Voles forced to remain in an overcrowded fenced population do not suffer high mortality rates and continue to reproduce at abnormally high densities until starvation overtakes them. The initial behavioral interactions associated with crowding do not seem sufficient to cause voles to die in situ. What happens to animals during the population decline? Our studies have not answered this question. The animals did not appear to disperse, but it is possible that the method we used to measure dispersal (movement into a vacant habitat) missed a large segment of dispersing voles which did not remain in the vacant area but kept on moving. Perhaps the dispersal during the increase phase of the population cycle is a colonization type of dispersal, and the animals taking part in it are likely to stay in a new habitat, while during the population decline dispersal is a pathological response to high density, and the animals are not attracted to settling even in a vacant habitat. The alternative to this suggestion is that animals are dying in situ during the decline because of physiological or genetically determined behavioral stress. Thus the fencing of a population prevents the change in rates of survival and reproduction, from high rates in the increase phase to low rates in the decline phase, and the fenced populations resemble "mouse plagues." A possible explanation is that the differential dispersal of animals during the phase of increase causes the quality of the voles remaining at peak densities in wild populations to be different from the quality of voles at much higher densities in enclosures. Increased sensitivity to density in Microtus could cause the decline of wild populations at densities lower than those reached by fenced populations in which selection through dispersal has been prevented. Fencing might also alter the social interactions among Microtus in other ways that are not understood. The analysis of colonizing species by MacArthur and Wilson (27) can be applied to our studies of dispersal in populations of Microtus. Groups of organisms with good dispersal and colonizing ability are called r strategists because they have high reproductive potential and are able to exploit a new environment rapidly. Dispersing voles seem to be r strategists. Young females in breeding condition were over-represented in dispersing female Microtus (17). The Tf(C)/Tf(E) females, which were more common among dispersers during the phase of population increase (Fig. 6), also have a slight reproductive advantage over the other Tf genotypes (19). Thus in Microtus populations the animals with the highest reproductive potential, the r strategists, are dispersing. The segment of the population which remains behind after the selection-via-dispersal are those individuals which are less influenced by increasing population densities. These are the individuals which maximize use of the habitat, the K strategists in MacArthur and Wilson's terminology, or voles selected for spacing behavior. Thus we can describe population cycles in Microtus in the same theoretical framework as colonizing species on islands. Our work on Microtus is consistent with the hypothesis of genetic and behavioral effects proposed by Chitty (6) (Fig. 7) in that it shows both behavioral differences in males during the phases of population fluctuation and periods of strong genetic selection. The greatest gaps in our knowledge are in the area of genetic-behavioral interactions which are most difficult to measure. We have no information on the heritability of aggressive behavior in voles. The pathways by which behavioral events are translated into physiological changes which affect reproduction and growth have been carefully analyzed by Christian and his associates (28) for rodents in laboratory situations, but the application of these findings to the complex field events described above remains to be done. Several experiments are suggested by our work. First, other populations of other rodent species should increase to abnormal densities if enclosed in a large fenced area (29). We need to find situations in which this prediction is not fulfilled. Island populations may be an important source of material for such an experiment (30). Second, if one-way exit doors were provided from a fenced area, normal population regulation through dispersal should occur. This experiment would provide another method by which dispersers could be identified. Third, if dispersal were prevented after a population reached peak densities, a normal decline phase should occur. This prediction is based on the assumption that dispersal during the increase phase is sufficient to ensure the decline phase 1 or 2 years later. All these experiments are concerned with the dispersal factor, and our work on Microtus can be summarized by the admonition: study dispersal.

Ohio River Environmental Assessment: Cultural Resources Reconnaissance Report, West Virginia.

DTIC Science & Technology

1977-08-01

that Paleo-Indian populations consisted of nomadic hunting bands that ranged over large territories. Population density in the project area appears to...Complex which is present in Ohio and filters sporadically to the floodplain (Prufer and Baby 1963) during this period appears to be absent in West Virignia...riverine and estuarine resources as well as hunting and gathering (Caldwell, 1958). Sites are variable in size and density with some indications of

The inequitable distribution of tobacco outlet density: the role of income in two Black Mid-Atlantic geopolitical areas.

PubMed

Fakunle, D O; Milam, A J; Furr-Holden, C D; Butler, J; Thorpe, R J; LaVeist, T A

2016-07-01

Studies have shown that communities with higher concentrations of low-income racial and ethnic minorities correlate with a greater presence of tobacco outlets. Community-level income has consistently been among the strongest predictors of tobacco outlet density. This study analyzes two Maryland geopolitical areas with similar racial concentrations yet differing income levels in an attempt to disentangle the race-income relationship with tobacco outlet density. In this cross-sectional examination of tobacco outlet and census tract-level sociodemographic data, Baltimore City, Maryland, and Prince George's County, Maryland, were geocoded to determine tobacco outlet density. Tobacco outlet density was defined as the mean number of tobacco outlets per 1000 persons per census tract. Comparisons of tobacco outlet density and sociodemographic variables were analysed via two-sample t-tests, and the direct effect of sociodemographic variables on tobacco outlet density for each area was analysed via spatial lag regressions. Prince George's County, the area with the higher income level ($77,190 vs $43,571), has a significantly lower tobacco outlet density than Baltimore City (P < 0.001). Prince George's County has a 67.5% Black population and an average of 3.94 tobacco outlets per 1000 persons per tract. By contrast, Baltimore City has a 65.3% Black population and an average of 7.95 tobacco outlets per 1000 persons per tract. Spatial lag regression model results indicate an inverse relationship between income and tobacco outlet density in Baltimore City and Prince George's County (β = -0.03, P < 0.01 &β = -0.01, P = 0.02, respectively), and a significant interaction term indicating a greater magnitude in the relationship between income and tobacco outlet density in Baltimore City (β = -0.05, P < 0.01). Results suggest that higher socio-economic status, even in primarily underrepresented racial and ethnic geopolitical areas, is linked to lower tobacco outlet density. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub

PubMed Central

Carlson, Jane E.; Adams, Christopher A.; Holsinger, Kent E.

2016-01-01

Background and Aims Trait–environment relationships are commonly interpreted as evidence for local adaptation in plants. However, even when selection analyses support this interpretation, the mechanisms underlying differential benefits are often unknown. This study addresses this gap in knowledge using the broadly distributed South African shrub Protea repens. Specifically, the study examines whether broad-scale patterns of trait variation are consistent with spatial differences in selection and ecophysiology in the wild. Methods In a common garden study of plants sourced from 19 populations, associations were measured between five morphological traits and three axes describing source climates. Trait–trait and trait–environment associations were analysed in a multi-response model. Within two focal populations in the wild, selection and path analyses were used to test associations between traits, fecundity and physiological performance. Key Results Across 19 populations in a common garden, stomatal density increased with the source population’s mean annual temperature and decreased with its average amount of rainfall in midsummer. Concordantly, selection analysis in two natural populations revealed positive selection on stomatal density at the hotter, drier site, while failing to detect selection at the cooler, moister site. Dry-site plants with high stomatal density also had higher stomatal conductances, cooler leaf temperatures and higher light-saturated photosynthetic rates than those with low stomatal density, but no such relationships were present among wet-site plants. Leaf area, stomatal pore index and specific leaf area in the garden also co-varied with climate, but within-population differences were not associated with fitness in either wild population. Conclusions The parallel patterns of broad-scale variation, differences in selection and differences in trait–ecophysiology relationships suggest a mechanism for adaptive differentiation in stomatal density. Densely packed stomata may improve performance by increasing transpiration and cooling, but predominately in drier, hotter climates. This study uniquely shows context-dependent benefits of stomatal density – a trait rarely linked to local adaptation in plants. PMID:26424782

Obesity and Regional Immigrant Density.

PubMed

Emerson, Scott D; Carbert, Nicole S

2017-11-24

Canada has an increasingly large immigrant population. Areas of higher immigrant density, may relate to immigrants' health through reduced acculturation to Western foods, greater access to cultural foods, and/or promotion of salubrious values/practices. It is unclear, however, whether an association exists between Canada-wide regional immigrant density and obesity among immigrants. Thus, we examined whether regional immigrant density was related to obesity, among immigrants. Adult immigrant respondents (n = 15,595) to a national population-level health survey were merged with region-level immigrant density data. Multi-level logistic regression was used to model the odds of obesity associated with increased immigrant density. The prevalence of obesity among the analytic sample was 16%. Increasing regional immigrant density was associated with lower odds of obesity among minority immigrants and long-term white immigrants. Immigrant density at the region-level in Canada may be an important contextual factor to consider when examining obesity among immigrants.

Regulation of the seasonal population patterns of Helicoverpa armigera moths by Bt cotton planting.

PubMed

Gao, Yu-Lin; Feng, Hong-Qiang; Wu, Kong-Ming

2010-08-01

Transgenic cotton expressing the Bacillus thuringiensis (Bt) Cry1Ac toxin has been commercially cultivated in China since 1997, and by 2000 Bt cotton had almost completely replaced non-transgenic cotton cultivars. To evaluate the impact of Bt cotton planting on the seasonal population patterns of cotton bollworm, Helicoverpa armigera, the dynamics of H. armigera moths were monitored with light traps from four locations (Xiajin, Linqing and Dingtao of Shandong Province; Guantao of Hebei Province) in high Bt density region and five locations (Anci and Xinji of Hebei Province; Dancheng and Fengqiu of Henan Province; Gaomi of Shandong Province) in low Bt density region from 1996 to 2008. A negative correlation was found between moth densities of H. armigera and the planting years of Bt cotton in both high and low Bt density areas. These data indicate that the moth population density of H. armigera was reduced with the introduction of Bt cotton in northern China. Three generations of moths occurred between early June and late September in the cotton regions. Interestingly, second-generation moths decreased and seemed to vanish in recent years in high Bt density region, but this tendency was not found in low Bt density region. The data suggest that the planting of Bt cotton in high Bt density region was effective in controlling the population density of second-generation moths. Furthermore, the seasonal change of moth patterns associated with Bt cotton planting may regulate the regional occurrence and population development of this migratory insect.

The densest terrestrial vertebrate

USGS Publications Warehouse

Rodda, G.H.; Perry, G.; Rondeau, R.J.; Lazell, J.

2001-01-01

An understanding of the abundance of organisms is central to understanding ecology, but many population density estimates are unrepresentative because they were obtained from study areas chosen for the high abundance of the target species. For example, from a pool of 1072 lizard density estimates that we compiled from the literature, we sampled 303 estimates and scored each for its assessment of the degree to which the study site was representative. Less than half (45%) indicated that the study area was chosen to be representative of the population or habitat. An additional 15% reported that individual plots or transects were chosen randomly, but this often indicated only that the sample points were located randomly within a study area chosen for its high abundance of the target species. The remainder of the studies either gave no information or specified that the study area was chosen because the focal species was locally abundant.

The effect of urban street gang densities on small area homicide incidence in a large metropolitan county, 1994-2002.

PubMed

Robinson, Paul L; Boscardin, W John; George, Sheba M; Teklehaimanot, Senait; Heslin, Kevin C; Bluthenthal, Ricky N

2009-07-01

The presence of street gangs has been hypothesized as influencing overall levels of violence in urban communities through a process of gun-drug diffusion and cross-type homicide. This effect is said to act independently of other known correlates of violence, i.e., neighborhood poverty. To test this hypothesis, we independently assessed the impact of population exposure to local street gang densities on 8-year homicide rates in small areas of Los Angeles County, California. Homicide data from the Los Angeles County Coroners Office were analyzed with original field survey data on street gang locations, while controlling for the established covariates of community homicide rates. Bivariate and multivariate regression analyses explicated strong relationships between homicide rates, gang density, race/ethnicity, and socioeconomic structure. Street gang densities alone had cumulative effects on small area homicide rates. Local gang densities, along with high school dropout rates, high unemployment rates, racial and ethnic concentration, and higher population densities, together explained 90% of the variation in local 8-year homicide rates. Several other commonly considered covariates were insignificant in the model. Urban environments with higher densities of street gangs exhibited higher overall homicide rates, independent of other community covariates of homicide. The unique nature of street gang killings and their greater potential to influence future local rates of violence suggests that more direct public health interventions are needed alongside traditional criminal justice mechanisms to combat urban violence and homicides.

Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa

USGS Publications Warehouse

Judge, Seth W.; Camp, Richard J.; Hart, Patrick J.; Kichman, Scott T.

2018-01-01

Endangered Hawai‘i ʻĀkepas (Loxops coccineus) are endemic to Hawai‘i island, where they occur in five spatially distinct populations. Data concerning the status and population trends of these unique Hawaiian honeycreepers are crucial for assessing the effectiveness of recovery and management actions. In 2016, we used point‐transect distance sampling to estimate the abundance of Hawai‘i ʻĀkepas in portions of Hawai‘i Volcanoes National Park (HAVO) and the Kaʻū Forest Reserve (KFR) on Mauna Loa volcano. We then compiled the survey data from four other populations to provide a global population estimate. In our HAVO and KFR study area, we mapped habitat classes to determine the population densities in each habitat. Densities were highest (1.03 birds/ha) in open‐canopy montane ʻōhiʻa (Metrosideros polymorpha) woodland. In contrast, densities of the largest ʻĀkepa population on Mauna Kea volcano were highest in closed‐canopy ʻōhiʻa and koa (Acacia koa) forest where the species is dependent on nest cavities in tall (> 15 m), large (> 50‐cm diameter at breast height) trees. We surveyed potential nesting habitat in HAVO and KFR and found only one cavity in the short‐stature montane ʻōhiʻa woodland and five cavities in the tall‐stature forest. Differences in densities between the Mauna Kea and Mauna Loa populations suggest that Hawai‘i ʻĀkepas may exhibit different foraging and nesting behaviors in the two habitats. The estimated overall population density in the HAVO and KFR study area was 0.52 birds/ha, which equates to 3663 (95% CI 1725–6961) birds in their 11,377‐ha population range. We calculated a global population of 16,428 (95% CI 10,065–25,198) birds, which is similar to an estimate of 13,892 (95% CI 10,315–17,469) birds made in 1986. Our results suggest that populations are stable to increasing in the two largest populations, but the three other populations are smaller (range = 77–1443 birds) and trends for those populations are unknown.

Resolving the interactions between population density and air pollution emissions controls in the San Joaquin Valley, USA.

PubMed

Hixson, Mark; Mahmud, Abdullah; Hu, Jianlin; Kleeman, Michael J

2012-05-01

The effectiveness of emissions control programs designed to reduce concentrations of airborne particulate matter with an aerodynamic diameter < 2.5 microm (PM2.5) in California's San Joaquin Valley was studied in the year 2030 under three growth scenarios: low, medium, and high population density. Base-case inventories for each choice of population density were created using a coupled emissions modeling system that simultaneously considered interactions between land use and transportation, area source, and point source emissions. The ambient PM2.5 response to each combination of population density and emissions control was evaluated using a regional chemical transport model over a 3-week winter stagnation episode. Comparisons between scenarios were based on regional average and population-weighted PM2.5 concentrations. In the absence of any emissions control program, population-weighted concentrations of PM2.5 in the future San Joaquin Valley are lowest undergrowth scenarios that emphasize low population density. A complete ban on wood burning and a 90% reduction in emissions from food cooking operations and diesel engines must occur before medium- to high-density growth scenarios result in lower population-weighted concentrations of PM2.5. These trends partly reflect the fact that existing downtown urban cores that naturally act as anchor points for new high-density growth in the San Joaquin Valley are located close to major transportation corridors for goods movement. Adding growth buffers around transportation corridors had little impact in the current analysis, since the 8-km resolution of the chemical transport model already provided an artificial buffer around major emissions sources. Assuming that future emissions controls will greatly reduce or eliminate emissions from residential wood burning, food cooking, and diesel engines, the 2030 growth scenario using "as-planned" (medium) population density achieves the lowest population-weighted average PM2.5 concentration in the future San Joaquin Valley during a severe winter stagnation event. The San Joaquin Valley is one of the most heavily polluted air basins in the United States that are projected to experience strong population growth in the coming decades. The best plan to improve air quality in the region combines medium- or high-density population growth with rigorous emissions controls. In the absences of controls, high-density growth leads to increased population exposure to PM2.5 compared with low-density growth scenarios (urban sprawl).

Population dynamics, structure and behavior of Anopheles darlingi in a rural settlement in the Amazon rainforest of Acre, Brazil

PubMed Central

2011-01-01

Background Anopheles darlingi is the major vector of malaria in South America, and its behavior and distribution has epidemiological importance to biomedical research. In Brazil, An. darlingi is found in the northern area of the Amazon basin, where 99.5% of the disease is reported. Methods The study area, known as Ramal do Granada, is a rural settlement inside the Amazon basin in the state of Acre. Population variations and density have been analysed by species behaviour, and molecular analysis has been measured by ND4 mitochondrial gene sequencing. Results The results show higher density in collections near a recent settlement, suggesting that a high level of colonization decreases the vector presence. The biting activity showed higher activity at twilight and major numbers of mosquitos in the remaining hours of the night in months of high density. From a sample of 110 individual mosquitoes, 18 different haplotypes were presented with a diversity index of 0.895, which is higher than that found in other Anopheles studies. Conclusions An. darlingi depends on forested regions for their larval and adult survival. In months with higher population density, the presence of mosquitoes persisted in the second part of the night, increasing the vector capacity of the species. Despite the intra-population variation in the transition to rainy season, the seasonal distribution of haplotypes shows no change in the structure population of An. darlingi. PMID:21702964

[The dose estimation to the population as a result of radioactive contamination of the Semipalatinsk Test area].

PubMed

Spiridonova, S I; Mukusheva, M K; Shubina, O A; Solomatin, V M; Epifanova, I E

2008-01-01

The results are presented from estimation of spatial distribution of 137Cs and 90Sr contamination densities in the areas of horses and sheep grazing within the Semipalatinsk Test Site. Dose burdens to various cohorts of the population living within the STS and consuming contaminated animal products are predicted. Doses of shepherds in the most contaminated pasture areas have been found to exceed the accepted limit (1 mSv/y). The conclusion is made about the need for further studies on the risk assessment of the STS population exposure above the accepted limits.

An ecological study of the locations of schools and child pedestrian injury collisions.

PubMed

LaScala, Elizabeth A; Gruenewald, Paul J; Johnson, Fred W

2004-07-01

Geographic studies of the incidence and prevalence of child pedestrian injury collisions in different community environments have been primarily descriptive and idiosyncratic, reflecting one or another likely determinant of the places where these injuries occur. The current study maintains that multiple determinants of child pedestrian injury collisions must be considered in evaluating the unique contributions of any one community feature to injury rates. These features include local characteristics of populations, such as rates of unemployment, and places, such as locations of schools. Schools are one stable geographic feature associated with regular, often concentrated periods of complex and congested traffic patterns. The objective of the present study was to examine annual rates of child pedestrian injury in four California communities with a focus on the unique contribution of schools to injury risk. We predicted that annual numbers of child pedestrian injury collisions (both in-school and summer combined) would be greater in communities with higher youth population densities, more unemployment, fewer high-income households, and higher traffic flow. It was hypothesized that youth population density and its interaction with the number of schools in a given area would be related to greater rates of child pedestrian collisions during in-school months. An ecological approach was taken that divided the four communities into 102 geographic units with an average of 6321 people residing in each unit. Archival data on traffic flow, number of child pedestrian injury collisions and locations of schools were obtained from state agencies. Individual-level data were obtained from a general population survey conducted in the communities. The results showed that annual numbers of injuries were greater in areas with higher youth population densities, more unemployment, fewer high-income households, and greater traffic flow. Annual numbers of injuries during in-school months were greater in areas containing middle schools and greater population densities of youth.

Variability of footprint ridge density and its use in estimation of sex in forensic examinations.

PubMed

Krishan, Kewal; Kanchan, Tanuj; Pathania, Annu; Sharma, Ruchika; DiMaggio, John A

2015-10-01

The present study deals with a comparatively new biometric parameter of footprints called footprint ridge density. The study attempts to evaluate sex-dependent variations in ridge density in different areas of the footprint and its usefulness in discriminating sex in the young adult population of north India. The sample for the study consisted of 160 young adults (121 females) from north India. The left and right footprints were taken from each subject according to the standard procedures. The footprints were analysed using a 5 mm × 5 mm square and the ridge density was calculated in four different well-defined areas of the footprints. These were: F1 - the great toe on its proximal and medial side; F2 - the medial ball of the footprint, below the triradius (the triradius is a Y-shaped group of ridges on finger balls, palms and soles which forms the basis of ridge counting in identification); F3 - the lateral ball of the footprint, towards the most lateral part; and F4 - the heel in its central part where the maximum breadth at heel is cut by a perpendicular line drawn from the most posterior point on heel. This value represents the number of ridges in a 25 mm(2) area and reflects the ridge density value. Ridge densities analysed on different areas of footprints were compared with each other using the Friedman test for related samples. The total footprint ridge density was calculated as the sum of the ridge density in the four areas of footprints included in the study (F1 + F2 + F3 + F4). The results show that the mean footprint ridge density was higher in females than males in all the designated areas of the footprints. The sex differences in footprint ridge density were observed to be statistically significant in the analysed areas of the footprint, except for the heel region of the left footprint. The total footprint ridge density was also observed to be significantly higher among females than males. A statistically significant correlation is shown in the ridge densities among most areas of both left and right sides. Based on receiver operating characteristic (ROC) curve analysis, the sexing potential of footprint ridge density was observed to be considerably higher on the right side. The sexing potential for the four areas ranged between 69.2% and 85.3% on the right side, and between 59.2% and 69.6% on the left side. ROC analysis of the total footprint ridge density shows that the sexing potential of the right and left footprint was 91.5% and 77.7% respectively. The study concludes that footprint ridge density can be utilised in the determination of sex as a supportive parameter. The findings of the study should be utilised only on the north Indian population and may not be internationally generalisable. © The Author(s) 2014.

Study of the Relationships between the Spatial Extent of Surface Urban Heat Islands and Urban Characteristic Factors Based on Landsat ETM+ Data

PubMed Central

Zhang, Jinqu; Wang, Yunpeng

2008-01-01

Ten cities with different population and urban sizes located in the Pearl River Delta, Guangdong Province, P.R. China were selected to study the relationships between the spatial extent of surface urban heat islands (SUHI) and five urban characteristic factors such as urban size, development area, water proportion, mean NDVI (Normalized Vegetation Index) and population density, etc. The spatial extent of SUHI was quantified by using the hot island area (HIA). All the cities are almost at the same latitude, showing similar climate and solar radiation, the influence of which could thus be eliminated during our computation and comparative study. The land surface temperatures (LST) were retrieved from the data of Landsat 7 Enhanced Thematic Mapper Plus (ETM+) band 6 using a mono-window algorithm. A variance-segmenting method was proposed to compute HIA for each city from the retrieved LST. Factors like urban size, development area and water proportion were extracted directly from the classification images of the same ETM+ data and the population density factor is from the official census. Correlation and regression analyses were performed to study the relationships between the HIA and the related factors, and the results show that HIA is highly correlated to urban size (r=0.95), population density (r=0.97) and development area (r=0.83) in this area. It was also proved that a weak negative correlation existed between HIA and both mean NDVI and water proportion for each city. Linear functions between HIA and its related factors were established, respectively. The HIA can reflect the spatial extent and magnitude of the surface urban heat island effect, and can be used as reference in the urban planning. PMID:27873939

Population as a proxy for infrastructure in the determination of event response and recovery resource allocations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stamber, Kevin L.; Unis, Carl J.; Shirah, Donald N.

Research into modeling of the quantification and prioritization of resources used in the recovery of lifeline critical infrastructure following disruptive incidents, such as hurricanes and earthquakes, has shown several factors to be important. Among these are population density and infrastructure density, event effects on infrastructure, and existence of an emergency response plan. The social sciences literature has a long history of correlating the population density and infrastructure density at a national scale, at a country-to-country level, mainly focused on transportation networks. This effort examines whether these correlations can be repeated at smaller geographic scales, for a variety of infrastructure types,more » so as to be able to use population data as a proxy for infrastructure data where infrastructure data is either incomplete or insufficiently granular. Using the best data available, this effort shows that strong correlations between infrastructure density for multiple types of infrastructure (e.g. miles of roads, hospital beds, miles of electric power transmission lines, and number of petroleum terminals) and population density do exist at known geographic boundaries (e.g. counties, service area boundaries) with exceptions that are explainable within the social sciences literature. Furthermore, the correlations identified provide a useful basis for ongoing research into the larger resource utilization problem.« less

Population as a proxy for infrastructure in the determination of event response and recovery resource allocations

DOE PAGES

Stamber, Kevin L.; Unis, Carl J.; Shirah, Donald N.; ...

2016-04-01

Research into modeling of the quantification and prioritization of resources used in the recovery of lifeline critical infrastructure following disruptive incidents, such as hurricanes and earthquakes, has shown several factors to be important. Among these are population density and infrastructure density, event effects on infrastructure, and existence of an emergency response plan. The social sciences literature has a long history of correlating the population density and infrastructure density at a national scale, at a country-to-country level, mainly focused on transportation networks. This effort examines whether these correlations can be repeated at smaller geographic scales, for a variety of infrastructure types,more » so as to be able to use population data as a proxy for infrastructure data where infrastructure data is either incomplete or insufficiently granular. Using the best data available, this effort shows that strong correlations between infrastructure density for multiple types of infrastructure (e.g. miles of roads, hospital beds, miles of electric power transmission lines, and number of petroleum terminals) and population density do exist at known geographic boundaries (e.g. counties, service area boundaries) with exceptions that are explainable within the social sciences literature. Furthermore, the correlations identified provide a useful basis for ongoing research into the larger resource utilization problem.« less

Comparing population and incident data for optimal air ambulance base locations in Norway.

PubMed

Røislien, Jo; van den Berg, Pieter L; Lindner, Thomas; Zakariassen, Erik; Uleberg, Oddvar; Aardal, Karen; van Essen, J Theresia

2018-05-24

Helicopter emergency medical services are important in many health care systems. Norway has a nationwide physician manned air ambulance service servicing a country with large geographical variations in population density and incident frequencies. The aim of the study was to compare optimal air ambulance base locations using both population and incident data. We used municipality population and incident data for Norway from 2015. The 428 municipalities had a median (5-95 percentile) of 4675 (940-36,264) inhabitants and 10 (2-38) incidents. Optimal helicopter base locations were estimated using the Maximal Covering Location Problem (MCLP) optimization model, exploring the number and location of bases needed to cover various fractions of the population for time thresholds 30 and 45 min, in green field scenarios and conditioned on the existing base structure. The existing bases covered 96.90% of the population and 91.86% of the incidents for time threshold 45 min. Correlation between municipality population and incident frequencies was -0.0027, and optimal base locations varied markedly between the two data types, particularly when lowering the target time. The optimal solution using population density data put focus on the greater Oslo area, where one third of Norwegians live, while using incident data put focus on low population high incident areas, such as northern Norway and winter sport resorts. Using population density data as a proxy for incident frequency is not recommended, as the two data types lead to different optimal base locations. Lowering the target time increases the sensitivity to choice of data.

Soil Bacterial Diversity Is Associated with Human Population Density in Urban Greenspaces.

PubMed

Wang, Haitao; Cheng, Minying; Dsouza, Melissa; Weisenhorn, Pamela; Zheng, Tianling; Gilbert, Jack A

2018-05-01

Urban greenspaces provide extensive ecosystem services, including pollutant remediation, water management, carbon maintenance, and nutrient cycling. However, while the urban soil microbiota underpin these services, we still have limited understanding of the factors that influence their distribution. We characterized soil bacterial communities from turf-grasses associated with urban parks, streets, and residential sites across a major urban environment, including a gradient of human population density. Bacterial diversity was significantly positively correlated with the population density; and species diversity was greater in park and street soils, compared to residential soils. Population density and greenspace type also led to significant differences in the microbial community composition that was also significantly correlated with soil pH, moisture, and texture. Co-occurrence network analysis revealed that microbial guilds in urban soils were well correlated. Abundant soil microbes in high density population areas had fewer interactions, while abundant bacteria in high moisture soils had more interactions. These results indicate the significant influence of changes in urban demographics and land-use on soil microbial communities. As urbanization is rapidly growing across the planet, it is important to improve our understanding of the consequences of urban zoning on the soil microbiota.

Evaluating call-count procedures for measuring local mourning dove populations

USGS Publications Warehouse

Armbruster, M.J.; Baskett, T.S.; Goforth, W.R.; Sadler, K.C.

1978-01-01

Seventy-nine mourning dove call-count runs were made on a 32-km route in Osage County, Missouri, May 1-August 31, 1971 and 1972. Circular study areas, each 61 ha, surrounding stop numbers 4 and 5, were delineated for intensive nest searches and population estimates. Tallies of cooing male doves along the entire call-count route were quite variable in repeated runs, fluctuating as much as 50 percent on consecutive days. There were no consistent relationships between numbers of cooing males tallied at stops 4 and 5 and the numbers of current nests or doves estimated to be present in the surrounding study areas. We doubt the suitability of call-count procedures to estimate precisely the densities of breeding pairs, nests or production of doves on small areas. Our findings do not dispute the usefulness of the national call-count survey as an index to relative densities of mourning doves during the breeding season over large portions of the United States, or as an index to annual population trends.

Dingoes (Canis dingo Meyer, 1793) continue to be an important reservoir host of Dirofilaria immitis in low density housing areas in Australia.

PubMed

Smout, Felicity A; Skerratt, Lee F; Butler, James R A; Johnson, Christopher N; Congdon, Bradley C

2016-01-15

Heartworm (Dirofilaria immitis) is a parasitic nematode responsible for canine and feline cardiopulmonary dirofilariasis and human zoonotic filariosis in both tropical and temperate regions throughout the world. Importantly, this study in the Wet Tropics of Far North Queensland found D. immitis remains at high prevalence (72.7%) in wild dingoes in low density housing areas in Australia. This prevalence is equivalent to the highest levels seen in wild dogs in Australia and represents an ongoing risk to domestic dogs, cats and humans. In contrast, in higher density residential areas prevalence was significantly lower (16.7%, p=0.001). It is possible that chemotherapeutic heartworm (HW) prevention in domestic dogs in these higher density housing areas is helping to control infection in the resident dingo population. Five dingoes killed in council control operations around Atherton, a non-endemic HW region in the Wet Tropics, were all negative for HW likely due to the colder climate of the region restricting transmission of the disease. This survey highlights the importance of dingoes as reservoir hosts of HW disease and that the subsequent risk of infection to companion animals and humans depends on local factors such as housing density, possibly linked to chemotherapeutic HW control in domestic dogs and climate. Our findings show that veterinary clinicians need to ensure that pet owners are aware of HW disease and do not become complacent about HW chemoprohylaxis in areas which support dingo populations. Copyright © 2015 Elsevier B.V. All rights reserved.

Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density.

PubMed

Sugiura, Natsuko; Doi, Kandai; Kato, Takuya; Morita, Tatsushi; Hayama, Shin-Ichi

2018-03-30

To examine outbreaks of mange in raccoon dogs (Nyctereutes procyonoides) with respect to population density, we analyzed camera trap videos, and isolated mites from raccoon dog carcasses. In a camera trapping survey, we categorized the skin condition of raccoon dogs, and used a number of independent videos to calculate the relative abundance index (RAI). The RAI of raccoon dogs with alopecia increased following an increase in the RAI of those without alopecia. Among 27 raccoon dog carcasses, 12 showed mange-compatible skin lesions. Sarcoptes scabiei was isolated from 11 of these raccoon dogs, indicating that sarcoptic mange was endemic in our study area. Therefore, a high relative population density may be a factor underlying epizootics of sarcoptic mange in raccoon dogs.

Identifying aspects of neighbourhood deprivation associated with increased incidence of schizophrenia.

PubMed

Bhavsar, Vishal; Boydell, Jane; Murray, Robin; Power, Paddy

2014-06-01

Several studies have found an association between area deprivation and incidence of schizophrenia. However, not all studies have concurred and definitions of deprivation have varied between studies. Relative deprivation and inequality seem to be particularly important, but which aspects of deprivation or how this effect might operate is not known. The Lambeth Early Onset case register is a database of all cases of first episode psychosis aged 16 to 35years from the London Borough of Lambeth, a highly urban area. We identified 405 people with first onset schizophrenia who presented between 2000 and 2007. We calculated the overall incidence of first onset schizophrenia and tested for an association with area-level deprivation, using a multi-domain index of deprivation (IMD 2004). Specific analyses into associations with individual sub-domains of deprivation were then undertaken. Incidence rates, directly standardized for age and gender, were calculated for Lambeth at two geographical levels (small and large neighbourhood level). The Poisson regression model predicting incidence rate ratios for schizophrenia using overall deprivation score was statistically significant at both levels after adjusting for ethnicity, ethnic density, population density and population turnover. The incidence rate ratio for electoral ward deprivation was 1.03 (95% CI=1.004-1.04) and for the super output area deprivation was 1.04 (95% CI=1.02-1.06). The individual domains of crime, employment deprivation and educational deprivation were statistically significant predictors of incidence but, after adjusting for the other domains as well as age, gender, ethnicity and population density, only crime and educational deprivation, remained statistically significant. Low income, poor housing and deprived living environment did not predict incidence. In a highly urban area, an association was found between area-level deprivation and incidence of schizophrenia, after controlling for age, gender, ethnicity and population density; high crime and low levels of education accounted for this. As both of these are potentially modifiable, this suggests a possible means to reduce the incidence of schizophrenia. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Relationships between brightness of nighttime lights and population density

NASA Astrophysics Data System (ADS)

Naizhuo, Z.

2012-12-01

Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly lit area, relatively large under-estimations would emerge in the urban core regions. Previous studies have shown that GDP, carbon dioxide emission, and electric power consumption strongly correlate to urban population (Ghosh et al., 2010; Sutton et al., 2007; Zhao et al., 2012). Thus, although this study only examined the relationships between brightness of nighttime lights and population density, the results can provide insight for the spatial disaggregations of socioeconomic data (e.g. GDP, carbon dioxide emission, and electric power consumption) using the satellite nighttime light image data. Simply distributing the socioeconomic data to each pixel in proportion to the DN value of the nighttime light images may generate relatively large errors. References Bharit N, Tatem AJ, Ferrari MJ, Grais RF, Djibo A, Grenfell BT, 2011. Science, 334:1424-1427. Ghosh T, Elvidge CD, Sutton PC, Baugh KE, Ziskin D, Tuttle BT, 2010. Energies, 3:1895-1913. Oda T, Maksyutov S, 2011. Atmospheric Chemistry and Physics, 11:543-556. Sutton PC, Elvidge CD, Ghosh T, 2007. International Journal of Ecological Economics and Statistics, 8:5-21. Zhao N, Ghosh T, Samson EL, 2012. International Journal of Remote sensing, 33:6304-6320.

Metropolitan planning organizations in Texas : overview and profiles : final report.

DOT National Transportation Integrated Search

2017-04-01

A metropolitan planning organization (MPO) has authority and responsibility for regional transportation planning in urbanized areas where the population is at least 50,000 and surrounding areas meet size/density criteria determined by the U.S. Census...

National Survey of Volunteer Pharmacy Preceptors: effects of region, practice setting, and population density on responses.

PubMed

Skrabal, Maryann Z; Jones, Rhonda M; Walters, Ryan W; Nemire, Ruth E; Soltis, Denise A; Kahaleh, Abby A; Hritcko, Philip M; Boyle, Cynthia J; Assemi, Mitra; Turner, Paul D

2010-06-01

To survey volunteer pharmacy preceptors regarding experiential education and determine whether differences in responses relate to such factors as geographic region, practice setting, and population density. An online survey was sent to 4396 volunteer experiential preceptors. The survey consisted of 41 questions asking the preceptor to comment on the experiential education environment. Experiential education administrators from 9 schools of pharmacy administered the survey to their volunteer preceptors in all regions (Northeast, Midwest, South, and West) of the United States, in various pharmacy practice settings, and areas of differing population densities. A total of 1163 (26.5%) preceptors responded. Regionally, preceptors in the West disagreed more than those in the Midwest and the South that they had enough time to spend with students to provide a quality experience and also required compensation less often than their counterparts in the Northeast and South. Concerning practice settings, hospital preceptors accepted students from more schools, had greater increases in requests, turned away more students, and spent less time with the students compared to preceptors in other settings. Population density differences reflected that preceptors at urban sites took and turned away more students than those at rural sites. Preceptors from rural areas spent more time with students and felt they were spending enough time with their students to provide quality experiences when compared to other preceptors. The results of this national volunteer preceptor survey may assist pharmacy school leaders in understanding how location, practice type, and population density affect experiential education, preceptor time-quality issues, and site compensation so they can take necessary actions to improve quality of student practice experiences.

Patterns of Carbon Storage and Greenhouse Gas Losses in Urban Residential Lawns

NASA Astrophysics Data System (ADS)

Contosta, A.; Varner, R.; Xiao, J.

2017-12-01

Population density and housing age are two factors believed to impact carbon (C) storage and greenhouse gas emissions in one of the most extensively managed landscapes in the U.S.: the urban lawn. Previous research focusing on either above- or below-ground C dynamics has also not explicitly considered how they interact to affect the net carbon balance in urban residential areas. We addressed this knowledge gap by quantifying both soil and vegetative C stocks and greenhouse gas fluxes across an urban gradient in Manchester, NH, USA that included 34 lawns comprising three population density categories, five housing age classes, and the interaction between them. Using a combination of both weekly, manual measurements and continuous, automated estimates, we also sampled emissions of CH4, CO2, and N2O within a subset of these lawns that represented a range of citywide population density and housing age characteristics and management practices. We found that neither above- nor below-ground C storage varied with population density, but both differed among housing age classes. Soil C storage increased with housing age and was highest in the oldest lawns sampled. By contrast, C stocks in aboveground, woody biomass was highest at intermediate ages and lowest in older and new parcels. Unlike C stocks, soil greenhouse gas emissions did not change among population density categories, housing age classes, or with irrigation and fertilization management, but instead followed temporal trends in soil moisture and temperature. Overall, our results suggest that drivers of C storage and greenhouse gas losses in urban residential areas may not be uniform and their accurate representation in Earth system models may require a variety of approaches.

Periodic habitat loss alters the competitive coexistence between brown trout and bullheads in a small stream over 34 years.

PubMed

Elliott, J M

2006-01-01

1. Changes in the population density of juvenile sea trout Salmo trutta L. and bullheads Cottus gobio L. were compared in a small stream over 34 years. Both species have a similar diet and obviously live in the same general habitat. Habitat loss was most marked in seven summer droughts: severest in 1976, 1983, 1984, 1995, and less severe but followed by autumn droughts in 1969, 1989 and 1993. The contrasting effects of habitat loss on the two species were examined. 2. For both species, the Ricker curvilinear model significantly fit (P < 0.001) the relationship between initial egg density and survivor density for successive life stages, even though egg densities were much lower for bullheads than trout. These analyses provided evidence for density-dependent population regulation and also identified extreme outliers, most being for year-classes affected by summer droughts. 3. The variable effects of changes in habitable area (= % wettable area in sampling section) were quantified by using the residuals, each residual being the absolute value expressed as a percentage of the expected value from the Ricker curve. Significant relationships between the residuals and habitable area showed that habitat loss had a marked effect on survivor density, this being negative for 0+ and 1+ trout, and positive for 0+, 1+ and 2+/3+ bullheads. 4. Therefore, during periods of habitat loss in the summer months, bullhead density increased at the expense of trout density. Low flows and a decrease in wettable area were associated with a marked reduction in habitat quality for drift-feeding trout and an increase in habitat quality, and perhaps also quantity, for benthic-feeding bullheads. This case study shows that, during a major perturbation, the relationship between the densities of two species can change markedly in favour of the less numerous species. The competitive coexistence between the two species is therefore a dynamic process that changes through time with periodic changes in the environment.

Neighbourhood Ethnic Density Effects on Behavioural and Cognitive Problems Among Young Racial/Ethnic Minority Children in the US and England: A Cross-National Comparison.

PubMed

Zhang, Nan; Beauregard, Jennifer L; Kramer, Michael R; Bécares, Laia

2017-01-01

Studies on adult racial/ethnic minority populations show that the increased concentration of racial/ethnic minorities in a neighbourhood-a so-called ethnic density effect-is associated with improved health of racial/ethnic minority residents when adjusting for area deprivation. However, this literature has focused mainly on adult populations, individual racial/ethnic groups, and single countries, with no studies focusing on children of different racial/ethnic groups or comparing across nations. This study aims to compare neighbourhood ethnic density effects on young children's cognitive and behavioural outcomes in the US and in England. We used data from two nationally representative birth cohort studies, the US Early Childhood Longitudinal Study-Birth Cohort and the UK Millennium Cohort Study, to estimate the association between own ethnic density and behavioural and cognitive development at 5 years of age. Findings show substantial heterogeneity in ethnic density effects on child outcomes within and between the two countries, suggesting that ethnic density effects may reflect the wider social and economic context. We argue that researchers should take area deprivation into account when estimating ethnic density effects and when developing policy initiatives targeted at strengthening and improving the health and development of racial and ethnic minority children.

Subalpine bumble bee foraging distances and densities in relation to flower availability.

PubMed

Elliott, Susan E

2009-06-01

Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never >1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.

Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub.

PubMed

Carlson, Jane E; Adams, Christopher A; Holsinger, Kent E

2016-01-01

Trait-environment relationships are commonly interpreted as evidence for local adaptation in plants. However, even when selection analyses support this interpretation, the mechanisms underlying differential benefits are often unknown. This study addresses this gap in knowledge using the broadly distributed South African shrub Protea repens. Specifically, the study examines whether broad-scale patterns of trait variation are consistent with spatial differences in selection and ecophysiology in the wild. In a common garden study of plants sourced from 19 populations, associations were measured between five morphological traits and three axes describing source climates. Trait-trait and trait-environment associations were analysed in a multi-response model. Within two focal populations in the wild, selection and path analyses were used to test associations between traits, fecundity and physiological performance. Across 19 populations in a common garden, stomatal density increased with the source population's mean annual temperature and decreased with its average amount of rainfall in midsummer. Concordantly, selection analysis in two natural populations revealed positive selection on stomatal density at the hotter, drier site, while failing to detect selection at the cooler, moister site. Dry-site plants with high stomatal density also had higher stomatal conductances, cooler leaf temperatures and higher light-saturated photosynthetic rates than those with low stomatal density, but no such relationships were present among wet-site plants. Leaf area, stomatal pore index and specific leaf area in the garden also co-varied with climate, but within-population differences were not associated with fitness in either wild population. The parallel patterns of broad-scale variation, differences in selection and differences in trait-ecophysiology relationships suggest a mechanism for adaptive differentiation in stomatal density. Densely packed stomata may improve performance by increasing transpiration and cooling, but predominately in drier, hotter climates. This study uniquely shows context-dependent benefits of stomatal density--a trait rarely linked to local adaptation in plants. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Positive and Negative Feedbacks and Free-Scale Pattern Distribution in Rural-Population Dynamics

PubMed Central

Alados, Concepción L.; Errea, Paz; Gartzia, Maite; Saiz, Hugo; Escós, Juan

2014-01-01

Depopulation of rural areas is a widespread phenomenon that has occurred in most industrialized countries, and has contributed significantly to a reduction in the productivity of agro-ecological resources. In this study, we identified the main trends in the dynamics of rural populations in the Central Pyrenees in the 20th C and early 21st C, and used density independent and density dependent models and identified the main factors that have influenced the dynamics. In addition, we investigated the change in the power law distribution of population size in those periods. Populations exhibited density-dependent positive feedback between 1960 and 2010, and a long-term positive correlation between agricultural activity and population size, which has resulted in a free-scale population distribution that has been disrupted by the collapse of the traditional agricultural society and by emigration to the industrialized cities. We concluded that complex socio-ecological systems that have strong feedback mechanisms can contribute to disruptive population collapses, which can be identified by changes in the pattern of population distribution. PMID:25474704

The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 Catchments (Version 2.1) for the Conterminous United States: 2010 US Census Housing Unit and Population Density

EPA Pesticide Factsheets

This dataset represents the population and housing unit density within individual, local NHDPlusV2 catchments and upstream, contributing watersheds based on 2010 US Census data. Densities are calculated for every block group and watershed averages are calculated for every local NHDPlusV2 catchment(see Data Sources for links to NHDPlusV2 data and Census Data). This data set is derived from The TIGER/Line Files and related database (.dbf) files for the conterminous USA. It was downloaded as Block Group-Level Census 2010 SF1 Data in File Geodatabase Format (ArcGIS version 10.0). The landscape raster (LR) was produced based on the data compiled from the questions asked of all people and about every housing unit. The (block-group population / block group area) and (block-group housing units / block group area) were summarized by local catchment and by watershed to produce local catchment-level and watershed-level metrics as a continuous data type (see Data Structure and Attribute Information for a description). Using a riparian buffer(see Process Steps), statistics were generated for areas within each catchment that are within 100 meters of the stream reach in an attempt to evaluate for the riparian zone.

Hypoxic areas, density-dependence and food limitation drive the body condition of a heavily exploited marine fish predator

PubMed Central

Käll, Filip; Hansson, Martin; Baranova, Tatjana; Karlsson, Olle; Lundström, Karl; Neuenfeldt, Stefan; Hjelm, Joakim

2016-01-01

Investigating the factors regulating fish condition is crucial in ecology and the management of exploited fish populations. The body condition of cod (Gadus morhua) in the Baltic Sea has dramatically decreased during the past two decades, with large implications for the fishery relying on this resource. Here, we statistically investigated the potential drivers of the Baltic cod condition during the past 40 years using newly compiled fishery-independent biological data and hydrological observations. We evidenced a combination of different factors operating before and after the ecological regime shift that occurred in the Baltic Sea in the early 1990s. The changes in cod condition related to feeding opportunities, driven either by density-dependence or food limitation, along the whole period investigated and to the fivefold increase in the extent of hypoxic areas in the most recent 20 years. Hypoxic areas can act on cod condition through different mechanisms related directly to species physiology, or indirectly to behaviour and trophic interactions. Our analyses found statistical evidence for an effect of the hypoxia-induced habitat compression on cod condition possibly operating via crowding and density-dependent processes. These results furnish novel insights into the population dynamics of Baltic Sea cod that can aid the management of this currently threatened population. PMID:27853557

The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 (Version 2.1) Catchments Riparian Buffer for the Conterminous United States: 2010 US Census Housing Unit and Population Density

EPA Pesticide Factsheets

This dataset represents the population and housing unit density within individual, local NHDPlusV2 catchments and upstream, contributing watersheds riparian buffers based on 2010 US Census data. Densities are calculated for every block group and watershed averages are calculated for every local NHDPlusV2 catchment(see Data Sources for links to NHDPlusV2 data and Census Data). This data set is derived from The TIGER/Line Files and related database (.dbf) files for the conterminous USA. It was downloaded as Block Group-Level Census 2010 SF1 Data in File Geodatabase Format (ArcGIS version 10.0). The landscape raster (LR) was produced based on the data compiled from the questions asked of all people and about every housing unit. The (block-group population / block group area) and (block-group housing units / block group area) were summarized by local catchment and by watershed to produce local catchment-level and watershed-level metrics as a continuous data type (see Data Structure and Attribute Information for a description).

Are neighbourhood food resources distributed inequitably by income and race in the USA? Epidemiological findings across the urban spectrum

PubMed Central

Richardson, Andrea S; Boone-Heinonen, Janne; Popkin, Barry M

2012-01-01

Objective Many recent policies focus on socioeconomic inequities in availability of healthy food stores and restaurants. Yet understanding of how socioeconomic inequities vary across neighbourhood racial composition and across the range from rural to urban settings is limited, largely due to lack of large, geographically and socio-demographically diverse study populations. Using a national sample, the authors examined differences in neighbourhood food resource availability according to neighbourhood-level poverty and racial/ethnic population in non-urban, low-density urban and high-density urban areas. Design Cross-sectional data from an observational cohort study representative of the US middle and high school-aged population in 1994 followed into young adulthood. Participants Using neighbourhood characteristics of participants in the National Longitudinal Study of Adolescent Health (Wave III, 2001–2002; n=13 995 young adults aged 18–28 years representing 7588 US block groups), the authors examined associations between neighbourhood poverty and race/ethnicity with neighbourhood food resource availability in urbanicity-stratified multivariable linear regression. Primary and secondary outcome measures Neighbourhood availability of grocery/supermarkets, convenience stores and fast-food restaurants (measured as number of outlets per 100 km roadway). Results Neighbourhood race and income disparities were most pronounced in low-density urban areas, where high-poverty/high-minority areas had lower availability of grocery/supermarkets (β coefficient (β)=–1.91, 95% CI –2.73 to –1.09) and convenience stores (β=–2.38, 95% CI –3.62 to –1.14) and greater availability of fast-food restaurants (β=4.87, 95% CI 2.26 to 7.48) than low-poverty/low-minority areas. However, in high-density urban areas, high-poverty/low-minority neighbourhoods had comparatively greater availability of grocery/supermarkets (β=8.05, 95% CI 2.52 to 13.57), convenience stores (β=2.89, 95% CI 0.64 to 5.14) and fast-food restaurants (β=4.03, 95% CI 1.97 to 6.09), relative to low-poverty/low-minority areas. Conclusions In addition to targeting disproportionate fast-food availability in disadvantaged dense urban areas, our findings suggest that policies should also target disparities in grocery/supermarket and fast-food restaurant availability in low-density areas. PMID:22505308

Measuring the Effective Sampling Area of a Pheromone Trap for Monitoring Population Density of Southern Pine Beetle (Coleoptera: Scolytidae)

Treesearch

Peter Turchin; Francois J. Odendaal

1996-01-01

Multifunnel traps baited with frontalin and turpentine have been used to investigate dispersal of southern pine beetles, Dendroctonus front Zimmermann, and are routinely used in the southern United States to monitor population trends of this serious forest pest. However, there is no quantitative data on the effective sampling area of these traps that would allow us to...

The determinants of county growth.

PubMed

Carlino, G A; Mills, E S

1987-02-01

The determinants of population and employment growth were explored from a broader interregional (as opposed to intraregional) perspective. Data for the 1970s, at the county level of disaggregation, were used to analyze the effects of economic, demographic, and climatic variables on population and employment growth in a simultaneous equation framework. The use of data from the more than 3000 US counties provides a considerably larger testing ground than those used in previous research. The point of departure was a conventional, general equilibrium model in which both households and producers are geographically mobile. The study's dependent variables refer to population, total, and manufacturing employment densities. Family income had a powerful effect in stimulating both population and employment density. A 10% increase in family income led to a 7.9% increase in total and a 9.2% increase in manufacturing employment densities. High family income must stand for high demand, and thus, firms are drawn to an area. High family income also drew households to an area. A 10% increase in family income led to a 5.5% increase in population density. High family income must represent "good" neighborhoods for households. High family income was positively correlated with population and employment density, but in other recent studies either a negative and significant relationship or an insignificant relationship were reported. Local taxes consist of the receipts of county government and those of municipalities, townships, school districts, and special districts within the county. The elasticities reported in Table 4 suggest that a 10% increase in such taxes resulted in about a 0.072% reduction in county population density during the decade. The Industrial Revenue Bonds (IRBs) and the percent of the labor force that is unionized are 2 potential policy instruments at the state level. The study results suggest that IRBs have not stimulated either manufacturing or total employment, and the coefficients were statistically insignificant in the structural equations. The elasticities imply that a 10% increase in percent union reduces total employment by 0.42% and manufacturing employment by 0.18%. The effect on population was tiny. Further, while not intended, the interstate highway program may have been a significant redistributor of population and employment but has not caused immigration of people and jobs from central cities.

Relationships between urbanization and the oak resource of the Minneapolis/St. Paul metropolitan area from 1991 to 1998

Treesearch

Kathryn Kromroy; Kathleen Ward; Paul Castillo; Jennifer Juzwik

2006-01-01

Urbanization was associated with loss and transformation of the oak forest in the Twin Cities (Minneapolis and St. Paul) metropolitan area (TCMA) over a recent 7-year interval. Between 1991 and 1998, urbanization increased based on several indicators: population density, area of developed land, and area of impervious surface?total impervious area and area within three...

Correlations between U.S. county annual cancer incidence and population density.

PubMed

Vares, David Ae; St-Pierre, Linda S; Persinger, Michael A

2015-01-01

Population density implicitly involves specific distances between living individuals who exhibit biophysical forces and energies. Objective was to investigate major data bases of cancer incidence and population data to help understand the emergent properties of diseases that become apparent only when large populations and areas are considered. Correlation analyses of the annual incidence (years 2007 to 2011) of cancer in counties (2,885) of the U.S. and population densities were convergent with these quantitative predictions and suggested an inflection threshold around 50 people per square mile. The potential role of subtle or even "non-local" factors coupled to averaged population density in the viability and mortality of the human species may serve as alternative explanations to the attribution of malignancy to "chance" factors. Calculations indicated average distances between the electric force dipole of the brains or bodies of human beings generate forces known to affect DNA extension and when distributed over the Compton wavelength of the electron could produce energies sufficient to affect the binding of base nucleotides. An inclusive science of human ecology might benefit from considering subtle forces and energies associated with the individual members within the habitat that could determine the probability of cellular anomalies.

Occupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape.

PubMed

Hill, Jason M; Diefenbach, Duane R

2014-06-01

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single-season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter-area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m(2). Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter-area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland (x = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the foreseeable future. © 2014 Society for Conservation Biology.

Probability of lek collapse is lower inside sage-grouse Core Areas: Effectiveness of conservation policy for a landscape species.

PubMed

Spence, Emma Suzuki; Beck, Jeffrey L; Gregory, Andrew J

2017-01-01

Greater sage-grouse (Centrocercus urophasianus) occupy sagebrush (Artemisia spp.) habitats in 11 western states and 2 Canadian provinces. In September 2015, the U.S. Fish and Wildlife Service announced the listing status for sage-grouse had changed from warranted but precluded to not warranted. The primary reason cited for this change of status was that the enactment of new regulatory mechanisms was sufficient to protect sage-grouse populations. One such plan is the 2008, Wyoming Sage Grouse Executive Order (SGEO), enacted by Governor Freudenthal. The SGEO identifies "Core Areas" that are to be protected by keeping them relatively free from further energy development and limiting other forms of anthropogenic disturbances near active sage-grouse leks. Using the Wyoming Game and Fish Department's sage-grouse lek count database and the Wyoming Oil and Gas Conservation Commission database of oil and gas well locations, we investigated the effectiveness of Wyoming's Core Areas, specifically: 1) how well Core Areas encompass the distribution of sage-grouse in Wyoming, 2) whether Core Area leks have a reduced probability of lek collapse, and 3) what, if any, edge effects intensification of oil and gas development adjacent to Core Areas may be having on Core Area populations. Core Areas contained 77% of male sage-grouse attending leks and 64% of active leks. Using Bayesian binomial probability analysis, we found an average 10.9% probability of lek collapse in Core Areas and an average 20.4% probability of lek collapse outside Core Areas. Using linear regression, we found development density outside Core Areas was related to the probability of lek collapse inside Core Areas. Specifically, probability of collapse among leks >4.83 km from inside Core Area boundaries was significantly related to well density within 1.61 km (1-mi) and 4.83 km (3-mi) outside of Core Area boundaries. Collectively, these data suggest that the Wyoming Core Area Strategy has benefited sage-grouse and sage-grouse habitat conservation; however, additional guidelines limiting development densities adjacent to Core Areas may be necessary to effectively protect Core Area populations.

Embargo on Lion Hunting Trophies from West Africa: An Effective Measure or a Threat to Lion Conservation?

PubMed Central

Bouché, Philippe; Crosmary, William; Kafando, Pierre; Doamba, Benoit; Kidjo, Ferdinand Claude; Vermeulen, Cédric; Chardonnet, Philippe

2016-01-01

The W-Arly-Pendjari (WAP) ecosystem, shared among Benin, Burkina Faso and Niger, represents the last lion stronghold of West Africa. To assess the impact of trophy hunting on lion populations in hunting areas of the WAP, we analyzed trends in harvest rates from 1999 to 2014. We also investigated whether the hunting areas with higher initial hunting intensity experienced steeper declines in lion harvest between 1999 and 2014, and whether lion densities in hunting areas were lower than in national parks. Lion harvest rate remained overall constant in the WAP. At initial hunting intensities below 1.5 lions/1000km2, most hunting areas experienced an increase in lion harvest rate, although that increase was of lower magnitude for hunting areas with higher initial hunting intensity. The proportion of hunting areas that experienced a decline in lion harvest rate increased at initial hunting intensities above 1.5 lions/1000km2. In 2014, the lion population of the WAP was estimated with a spoor count at 418 (230–648) adults and sub-adult individuals, comparable to the 311 (123–498) individuals estimated in the previous 2012 spoor survey. We found no significant lion spoor density differences between national parks and hunting areas. Hunting areas with higher mean harvest rates did not have lower lion densities. The ratio of large adult males, females and sub-adults was similar between the national parks and the hunting areas. These results suggested that the lion population was not significantly affected by hunting in the WAP. We concluded that a quota of 1 lion/1000km2 would be sustainable for the WAP. Based on our results, an import embargo on lion trophies from the WAP would not be justified. It could ruin the incentive of local actors to conserve lions in hunting areas, and lead to a drastic reduction of lion range in West Africa. PMID:27182985

Embargo on Lion Hunting Trophies from West Africa: An Effective Measure or a Threat to Lion Conservation?

PubMed

Bouché, Philippe; Crosmary, William; Kafando, Pierre; Doamba, Benoit; Kidjo, Ferdinand Claude; Vermeulen, Cédric; Chardonnet, Philippe

2016-01-01

The W-Arly-Pendjari (WAP) ecosystem, shared among Benin, Burkina Faso and Niger, represents the last lion stronghold of West Africa. To assess the impact of trophy hunting on lion populations in hunting areas of the WAP, we analyzed trends in harvest rates from 1999 to 2014. We also investigated whether the hunting areas with higher initial hunting intensity experienced steeper declines in lion harvest between 1999 and 2014, and whether lion densities in hunting areas were lower than in national parks. Lion harvest rate remained overall constant in the WAP. At initial hunting intensities below 1.5 lions/1000km2, most hunting areas experienced an increase in lion harvest rate, although that increase was of lower magnitude for hunting areas with higher initial hunting intensity. The proportion of hunting areas that experienced a decline in lion harvest rate increased at initial hunting intensities above 1.5 lions/1000km2. In 2014, the lion population of the WAP was estimated with a spoor count at 418 (230-648) adults and sub-adult individuals, comparable to the 311 (123-498) individuals estimated in the previous 2012 spoor survey. We found no significant lion spoor density differences between national parks and hunting areas. Hunting areas with higher mean harvest rates did not have lower lion densities. The ratio of large adult males, females and sub-adults was similar between the national parks and the hunting areas. These results suggested that the lion population was not significantly affected by hunting in the WAP. We concluded that a quota of 1 lion/1000km2 would be sustainable for the WAP. Based on our results, an import embargo on lion trophies from the WAP would not be justified. It could ruin the incentive of local actors to conserve lions in hunting areas, and lead to a drastic reduction of lion range in West Africa.

Long-term population survey of the Sulawesi black macaques (Macaca nigra) at Tangkoko Nature Reserve, North Sulawesi, Indonesia.

PubMed

Kyes, Randall C; Iskandar, Entang; Onibala, Jane; Paputungan, Umar; Laatung, Sylvia; Huettmann, Falk

2013-01-01

The Sulawesi black macaque (Macaca nigra) population at Tangkoko Nature Reserve in North Sulawesi, Indonesia has been the focus of periodic study for over 30 years. The population has shown considerable decline during much of that time. Here we present the results of a long-term population survey of the Tangkoko M. nigra, conducted over the past decade, to provide updated information and on-going assessment of the population. Line-transect sampling was conducted annually from 1999 to 2002 and 2005 to 2011 along the same transect during a 2- to 3-week survey period. Although further decline in the population was observed at the outset of the survey, over the subsequent 12-year period we have seen stability in the population parameters with evidence of modest increases in both group and population density. During the 1999-2002 survey periods, there was a mean group density of 3.6 groups/km(2) and a mean population density of 39.8 individuals/km(2) . During 2005-2011, mean group density increased to 3.8 groups/km(2) and mean population density was 51.4 individuals/km(2) . The 2011 survey data indicated an estimated group density of 4.3 groups/km(2) and a population density of 61.5 individuals/km(2) . Given that our transect was located in the core of the Tangkoko reserve, our density estimates should be limited to that area of the reserve. One explanation for the apparent stabilization of the population may be tied to the increasing and sustained number of training and research programs being conducted at the reserve. This collective effort by local and international groups may be helping to reduce illegal activity in the reserve (i.e., hunting and habitat destruction) and generate greater awareness of this critically endangered species. Without the continued vigilance afforded by the existing research and training programs and the support and involvement of the local people, the M. nigra at the Tangkoko Nature Reserve will likely face further decline. © 2012 Wiley Periodicals, Inc.

Trends and Characteristics of Rural and Small Town Canada. Working Paper No. 15.

ERIC Educational Resources Information Center

Biggs, Brian; And Others

This report summarizes demographic, economic, and social statistics on Canada's rural and small towns through 1989. Rural and small towns include areas with populations of less than 10,000 persons or a population density of less than 400 per square kilometer. The first section examines rural-urban differences in population trends and age…

Dynamics and distribution of black abalone populations at San Nicolas Island

USGS Publications Warehouse

VanBlaricom, Glenn R.; Hochberg, F.G.

1993-01-01

Dense populations of black abalones (Haliotis cracherodii Leach) were monitored in permanent intertidal plots at nine sites on San Nicolas Island from 1981 through 1990. Densities were essentially constant at all four sites along the north shore of the island throughout the study period. Densities at five sites along the south shore were more variable, possibly reflecting asynchronous variation in recruitment, mortality resulting from wave disturbance, and removal by people. Temporal variation of abalone densities apparently was not influenced by sea otters or abalone withering syndrome during this study. Abalones were strongly aggregated in space. Highest densities occurred in areas of irregular substrata, apparently as a result of preference for crevices and vertical faces. The locations of dense patches were persistent in time.

Intra-lake variation in maturity, fecundity, and spawning of slimy sculpins (Cottus cognatus) in southern Lake Ontario

USGS Publications Warehouse

Owens, Randall W.; Noguchi, George E.

1998-01-01

Knowledge of the spawning cycle and factors affecting fecundity of slimy sculpins (Cottus cognatus) are important in understanding the population dynamics of this species in large lake systems, like Lake Ontario. Fecundity and the spawning cycle of slimy sculpins were described from samples of slimy sculpins and their egg masses collected with bottom trawls during four annual surveys, April to October, 1988 to 1994. Incidence of gravid females and collections of their egg masses indicated that spawning by slimy sculpins likely occurred from late April to mid October in Lake Ontario. Protracted spawning by slimy sculpins in Lake Ontario is probably a function of the annual water temperature cycle at various depths. Mean length of gravid females was inversely related to density of slimy sculpins. Fecundity ranged from 55 to 1,157 eggs among fish 55 to 127 mm long, and for similar-sized fish, fecundity was inversely related to density of slimy sculpins. Fecundity was about 50% higher at Olcott, where population indices of slimy sculpins were low, compared with Nine Mile Point where indices were much higher. Somatic weight or total length were both good predictors of fecundity. Lipid content of slimy sculpins was lower in an area of high sculpin abundance than in an area of low sculpin abundance, suggesting that fecundity was a function of density-dependent food availability. In large aquatic ecosystems, samples from more than one area may be necessary to describe fecundity of a sedentary species like slimy sculpin, especially if fish densities vary considerably among geographic areas. Large geographic variations in fecundity may be an indicator of spatial imbalance of a species with its prey. Low fecundity may be a compensatory response to slimy sculpins to low food supplies, thereby limiting population growth.

Breast density in screening mammography in Indian population - Is it different from western population?

PubMed

Singh, Tulika; Khandelwal, Niranjan; Singla, Veenu; Kumar, Dileep; Gupta, Madhu; Singh, Gurpreet; Bal, Amanjit

2018-05-01

Mammography is the only method presently considered appropriate for mass screening of breast cancer. However, higher breast density was strongly associated with lower mammographic sensitivity. Breast density is also identified as independent and strongest risk factors for breast cancer. Studies have shown women with high breast density have four to six times increased risk of breast cancer as compare to women with fatty breast. It varies between different age group it generally decreases with increasing age in postmenopausal women and it can be different in different ethnic groups and people from different geographical areas. This study evaluates the breast density in Indian population and its relationship with the age. We reviewed of all screening mammography examinations performed from May 2012 to January 2015 at our institute PGIMER, Chandigarh, INDIA. Descriptive analyses were used to examine the association between age and breast density. A total of 6132 screening mammograms were performed. Each subgroup categorized by decade of age. There was a significant inverse relationship between age and breast density (P < .001). Twenty-two percent of patients between 40 and 49 years old had dense breasts. This percentage decreased to 9% of women in their 50s. Only 7% of women in their 60s and 8% of women in their 70s had dense breasts. This data has been compared with the Western study done in New York University (NYU) shows there is significant difference (P value <.05) in the breast density in Indian and Western population with more Indians having ACR Grade 1 and 2 and Western population having 2 and 3. We found an inverse relationship between patient age and mammographic breast density. However, there were a large proportion of young women who had lower grades of mammographic density which could potentially benefit from the use of routine screening mammography in this subgroup of patients. Moreover, the breast density of Indian population is less when compared to the Western population. This might suggest that mammography is a good modality of choice for screening Indian population. © 2017 Wiley Periodicals, Inc.

Dispersal-mediated effect of microhabitat availability and density dependence determine population dynamics of a forest floor web spider.

PubMed

Takada, Mayura B; Miyashita, Tadashi

2014-09-01

Landscapes in nature can be viewed as a continuum of small total habitable area with high fragmentation to widely spreading habitats. The dispersal-mediated rescue effect predominates in the former landscapes, while classical density-dependent processes generally prevail in widely spread habitats. A similar principle should be applied to populations of organisms utilizing microhabitats in limited supply. To test this hypothesis, we examined the population dynamics of a web spider, Neriene brongersmai, in 16 populations with varying degrees of microhabitat availability, and we explored whether: (i) high microhabitat availability improves survival rate during density-independent movement, while the resultant high density reduces survival rate in a density-dependent manner; and (ii) temporal population stability increases with microhabitat availability at the population level. Furthermore, we conducted two types of field experiments to verify whether high microhabitat availability actually reduces mortality associated with web-site movement. Field observations revealed that demographic change in N. brongersmai populations was affected by three factors at different stages, namely the microhabitat limitation from the early to late juvenile stages, the density dependence from the late juvenile to adult stages and the food limitation from the adult to the next early juvenile stages. In addition, there was a tendency for a positive association between population stability and microhabitat availability at the population level. A small-scale experiment, where the frequency of spider web relocation was equalized artificially, revealed that high microhabitat availability elevated the survival rate during a movement event between web-sites. The larger spatiotemporal scale experiment also revealed an improved spider survival rate following treatment with high microhabitat availability, even though spider density was kept at a relatively low level. The population dynamics of N. brongersmai can be determined primarily by density-independent processes based on web-site fragmentation and density-dependent processes driven by interference competition. We conclude that depending on the amount of habitat resources, the relative importance of the two contrasting paradigms-equilibrium and non-equilibrium-appears to vary, even within a particular system. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

[Entomologic study of loaiasis transmission in the Lekie area (Cameroon)].

PubMed

Demanou, M; Pion, S D; Boussinesq, M

2001-11-01

A number of cases of Loa encephalopathy have been recorded after ivermectin treatment in the Lekie Division, an area of degraded forest located in central Cameroon. An entomological study was carried out in a village of this region between May 1999 and April 2000 to determine whether the high microfilarial loads of Loa found in the population, which can exceed 10,000 microfilariae per ml of blood, were related to high densities of vector populations. The Chrysops collected at 10 catching stations, using hand nets, by persons standing by a wood fire, were dissected to evaluate their level of infection with Loa. The vectorial densities were three-fold higher in the forest stations than in those located near the habitations (2307 and 725 bites per man per year, respectively). These values are lower than those reported from similar studies in Cameroon, Congo and Gabon. Measurement of Chrysops densities does not seem to be an appropriate tool to evaluate the level of endemicity of loiasis, and to delineate the areas where there is a risk of post-ivermectin Loa encephalopathies.

Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density

PubMed Central

SUGIURA, Natsuko; DOI, Kandai; KATO, Takuya; MORITA, Tatsushi; HAYAMA, Shin-ichi

2018-01-01

To examine outbreaks of mange in raccoon dogs (Nyctereutes procyonoides) with respect to population density, we analyzed camera trap videos, and isolated mites from raccoon dog carcasses. In a camera trapping survey, we categorized the skin condition of raccoon dogs, and used a number of independent videos to calculate the relative abundance index (RAI). The RAI of raccoon dogs with alopecia increased following an increase in the RAI of those without alopecia. Among 27 raccoon dog carcasses, 12 showed mange-compatible skin lesions. Sarcoptes scabiei was isolated from 11 of these raccoon dogs, indicating that sarcoptic mange was endemic in our study area. Therefore, a high relative population density may be a factor underlying epizootics of sarcoptic mange in raccoon dogs. PMID:29353863

Survey of Hylobates agilis albibarbis in a logged peat-swamp forest: Sabangau catchment, Central Kalimantan.

PubMed

Buckley, Cara; Nekaris, K A I; Husson, Simon John

2006-10-01

Few data are available on gibbon populations in peat-swamp forest. In order to assess the importance of this habitat for gibbon conservation, a population of Hylobates agilis albibarbis was surveyed in the Sabangau peat-swamp forest, Central Kalimantan, Indonesia. This is an area of about 5,500 km(2) of selectively logged peat-swamp forest, which was formally gazetted as a national park during 2005. The study was conducted during June and July 2004 using auditory sampling methods. Five sample areas were selected and each was surveyed for four consecutive days by three teams of researchers at designated listening posts. Researchers recorded compass bearings of, and estimated distances to, singing groups. Nineteen groups were located. Population density is estimated to be 2.16 (+/-0.46) groups/km(2). Sightings occurring either at the listening posts or that were obtained by tracking in on calling groups yielded a mean group size of 3.4 individuals, hence individual gibbon density is estimated to be 7.4 (+/-1.59) individuals/km(2). The density estimates fall at the mid-range of those calculated for other gibbon populations, thus suggesting that peat-swamp forest is an important habitat for gibbon conservation in Borneo. A tentative extrapolation of results suggests a potential gibbon population size of 19,000 individuals within the mixed-swamp forest habitat sub-type in the Sabangau. This represents one of the largest remaining continuous populations of Bornean agile gibbons. The designation of the Sabangau forest as a national park will hopefully address the problem of illegal logging and hunting in the region. Further studies should note any difference in gibbon density post protection.

Modeling abundance effects in distance sampling

USGS Publications Warehouse

Royle, J. Andrew; Dawson, D.K.; Bates, S.

2004-01-01

Distance-sampling methods are commonly used in studies of animal populations to estimate population density. A common objective of such studies is to evaluate the relationship between abundance or density and covariates that describe animal habitat or other environmental influences. However, little attention has been focused on methods of modeling abundance covariate effects in conventional distance-sampling models. In this paper we propose a distance-sampling model that accommodates covariate effects on abundance. The model is based on specification of the distance-sampling likelihood at the level of the sample unit in terms of local abundance (for each sampling unit). This model is augmented with a Poisson regression model for local abundance that is parameterized in terms of available covariates. Maximum-likelihood estimation of detection and density parameters is based on the integrated likelihood, wherein local abundance is removed from the likelihood by integration. We provide an example using avian point-transect data of Ovenbirds (Seiurus aurocapillus) collected using a distance-sampling protocol and two measures of habitat structure (understory cover and basal area of overstory trees). The model yields a sensible description (positive effect of understory cover, negative effect on basal area) of the relationship between habitat and Ovenbird density that can be used to evaluate the effects of habitat management on Ovenbird populations.

Density estimation in a wolverine population using spatial capture-recapture models

USGS Publications Warehouse

Royle, J. Andrew; Magoun, Audrey J.; Gardner, Beth; Valkenbury, Patrick; Lowell, Richard E.; McKelvey, Kevin

2011-01-01

Classical closed-population capture-recapture models do not accommodate the spatial information inherent in encounter history data obtained from camera-trapping studies. As a result, individual heterogeneity in encounter probability is induced, and it is not possible to estimate density objectively because trap arrays do not have a well-defined sample area. We applied newly-developed, capture-recapture models that accommodate the spatial attribute inherent in capture-recapture data to a population of wolverines (Gulo gulo) in Southeast Alaska in 2008. We used camera-trapping data collected from 37 cameras in a 2,140-km2 area of forested and open habitats largely enclosed by ocean and glacial icefields. We detected 21 unique individuals 115 times. Wolverines exhibited a strong positive trap response, with an increased tendency to revisit previously visited traps. Under the trap-response model, we estimated wolverine density at 9.7 individuals/1,000-km2(95% Bayesian CI: 5.9-15.0). Our model provides a formal statistical framework for estimating density from wolverine camera-trapping studies that accounts for a behavioral response due to baited traps. Further, our model-based estimator does not have strict requirements about the spatial configuration of traps or length of trapping sessions, providing considerable operational flexibility in the development of field studies.

Extrapolating cetacean densities to quantitatively assess human impacts on populations in the high seas.

PubMed

Mannocci, Laura; Roberts, Jason J; Miller, David L; Halpin, Patrick N

2017-06-01

As human activities expand beyond national jurisdictions to the high seas, there is an increasing need to consider anthropogenic impacts to species inhabiting these waters. The current scarcity of scientific observations of cetaceans in the high seas impedes the assessment of population-level impacts of these activities. We developed plausible density estimates to facilitate a quantitative assessment of anthropogenic impacts on cetacean populations in these waters. Our study region extended from a well-surveyed region within the U.S. Exclusive Economic Zone into a large region of the western North Atlantic sparsely surveyed for cetaceans. We modeled densities of 15 cetacean taxa with available line transect survey data and habitat covariates and extrapolated predictions to sparsely surveyed regions. We formulated models to reduce the extent of extrapolation beyond covariate ranges, and constrained them to model simple and generalizable relationships. To evaluate confidence in the predictions, we mapped where predictions were made outside sampled covariate ranges, examined alternate models, and compared predicted densities with maps of sightings from sources that could not be integrated into our models. Confidence levels in model results depended on the taxon and geographic area and highlighted the need for additional surveying in environmentally distinct areas. With application of necessary caution, our density estimates can inform management needs in the high seas, such as the quantification of potential cetacean interactions with military training exercises, shipping, fisheries, and deep-sea mining and be used to delineate areas of special biological significance in international waters. Our approach is generally applicable to other marine taxa and geographic regions for which management will be implemented but data are sparse. © 2016 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

Estimating changes in urban land and urban population using refined areal interpolation techniques

NASA Astrophysics Data System (ADS)

Zoraghein, Hamidreza; Leyk, Stefan

2018-05-01

The analysis of changes in urban land and population is important because the majority of future population growth will take place in urban areas. U.S. Census historically classifies urban land using population density and various land-use criteria. This study analyzes the reliability of census-defined urban lands for delineating the spatial distribution of urban population and estimating its changes over time. To overcome the problem of incompatible enumeration units between censuses, regular areal interpolation methods including Areal Weighting (AW) and Target Density Weighting (TDW), with and without spatial refinement, are implemented. The goal in this study is to estimate urban population in Massachusetts in 1990 and 2000 (source zones), within tract boundaries of the 2010 census (target zones), respectively, to create a consistent time series of comparable urban population estimates from 1990 to 2010. Spatial refinement is done using ancillary variables such as census-defined urban areas, the National Land Cover Database (NLCD) and the Global Human Settlement Layer (GHSL) as well as different combinations of them. The study results suggest that census-defined urban areas alone are not necessarily the most meaningful delineation of urban land. Instead, it appears that alternative combinations of the above-mentioned ancillary variables can better depict the spatial distribution of urban land, and thus make it possible to reduce the estimation error in transferring the urban population from source zones to target zones when running spatially-refined temporal areal interpolation.

Changing Urbania: Estimating Changes in Urban Land and Urban Population Using Refined Areal Interpolation Techniques

NASA Astrophysics Data System (ADS)

Zoraghein, H.; Leyk, S.; Balk, D.

2017-12-01

The analysis of changes in urban land and population is important because the majority of future population growth will take place in urban areas. The U.S. Census historically classifies urban land using population density and various land-use criteria. This study analyzes the reliability of census-defined urban lands for delineating the spatial distribution of urban population and estimating its changes over time. To overcome the problem of incompatible enumeration units between censuses, regular areal interpolation methods including Areal Weighting (AW) and Target Density Weighting (TDW), with and without spatial refinement, are implemented. The goal in this study is to estimate urban population in Massachusetts in 1990 and 2000 (source zones), within tract boundaries of the 2010 census (target zones), respectively, to create a consistent time series of comparable urban population estimates from 1990 to 2010. Spatial refinement is done using ancillary variables such as census-defined urban areas, the National Land Cover Database (NLCD) and the Global Human Settlement Layer (GHSL) as well as different combinations of them. The study results suggest that census-defined urban areas alone are not necessarily the most meaningful delineation of urban land. Instead it appears that alternative combinations of the above-mentioned ancillary variables can better depict the spatial distribution of urban land, and thus make it possible to reduce the estimation error in transferring the urban population from source zones to target zones when running spatially-refined temporal areal interpolation.

The Relationships between Two Different Drinking Water Fluoride Levels, Dental Fluorosis and Bone Mineral Density of Children

PubMed Central

Grobler, S.R; Louw, A.J; Chikte, U.M.E; Rossouw, R.J; van W Kotze, T.J.

2009-01-01

This field study included the whole population of children aged 10–15 years (77 from a 0.19 mg/L F area; 89 from a 3.00 mg/L F area), with similar nutritional, dietary habits and similar ethnic and socioeconomic status. The fluoride concentration in the drinking water, the bone mineral content, the bone density and the degree of dental fluorosis were determined. The left radius was measured for bone width, bone mineral content, and bone mineral density. The mean fluorosis score was 1.3 in the low fluoride area and 3,6 in the high fluoride area. More than half the children in the low fluoride area had no fluorosis (scores 0 and 1) while only 5% in the high fluoride area had none. Severe fluorosis (30%) was only observed in the high fluoride area. The Wilcoxon Rank Sum Test indicated that fluorosis levels differed significantly (p < 0.05) between the two areas. No relationships were found between dental fluorosis and bone width or between fluorosis and bone mineral density in the two areas (Spearment Rank correlations). A significant increase in bone width was found with age but no differences amongst and boys and girls. A significant positive correlation was found in the high fluoride area between bone mineral density over age. In the 12-13 and 13-14 year age groups in the high fluoride area, girls had higher bone mineral densities. However, a significant negative correlation (p<0.02) was found for the low fluoride area (0.19 mg/L F) over age. PMID:19444344

Not in wilderness: African vulture strongholds remain in areas with high human density.

PubMed

Henriques, Mohamed; Granadeiro, José Pedro; Monteiro, Hamilton; Nuno, Ana; Lecoq, Miguel; Cardoso, Paulo; Regalla, Aissa; Catry, Paulo

2018-01-01

Vultures constitute an important functional group in many ecosystems, providing crucial ecosystem services both in natural and humanized environments. These scavengers are facing massive declines worldwide, but in several African countries virtually nothing is known on populations' status and threats, hampering the development of adequate conservation strategies. In Guinea-Bissau, globally important populations of Hooded Necrosyrtes monachus and African white-backed vultures Gyps africanus were recently reported. Using the country as a study area, we aim to characterize human-vulture interactions in West Africa applying a multidisciplinary approach. We assessed the status and distribution of vulture populations using data from 1711 km of roadside transects, examined predictors of their distribution, and produced a nationwide population estimate for the Hooded Vulture, using an innovative method based on the relationship between the size of human population in settlements and vulture numbers. We conducted 47 stakeholder interviews to assess perceived roles played by vultures, and to investigate potential anthropogenic threats. Hooded vultures were strongly associated with high human population densities, whereas no relation was found between African white-backed and Rüppell's vultures and any of the tested predictors, which included cattle density, precipitation and Normalized Difference Vegetation Index, among others. We estimate a national population of 43347 Hooded vultures, the largest population reported in the species range. Respondents were generally aware of the services provided by vultures, especially waste and carcass removal, including in urban areas. Hunting for witchcraft and traditional medicine was the most frequently recognised threat, while poisoning was ranked as having the highest impact. We hypothesise that poisoning-related mortality may be affecting African white-backed and Rüppell's vultures' distribution and explain their scarcity in apparently highly suitable habitats. Our results suggest a mutualistic rather than a commensalistic relationship between vultures and humans, with important implications for designing and implementing conservation strategies.

Rapid genetic restoration of a keystone species exhibiting delayed demographic response.

PubMed

Cosentino, Bradley J; Schooley, Robert L; Bestelmeyer, Brandon T; McCarthy, Alison J; Sierzega, Kevin

2015-12-01

Genetic founder effects are often expected when animals colonize restored habitat in fragmented landscapes, but empirical data on genetic responses to restoration are limited. We examined the genetic response of banner-tailed kangaroo rats (Dipodomys spectabilis) to landscape-scale grassland restoration in the Chihuahuan Desert of New Mexico, USA. Dipodomys spectabilis is a grassland specialist and keystone species. At sites treated with herbicide to remove shrubs, colonization by D. spectabilis is slow and populations persist at low density for ≥10 years (≥6 generations). Persistence at low density and low gene flow may cause strong founder effects. We compared genetic structure of D. spectabilis populations between treated sites and remnant grasslands, and we examined how the genetic response to restoration depended on treatment age, area, and connectivity to source populations. Allelic richness and heterozygosity were similar between treated sites and remnant grasslands. Allelic richness at treated sites was greatest early in the restoration trajectory, and genetic divergence did not differ between recently colonized and established populations. These results indicated that founder effects during colonization of treated sites were weak or absent. Moreover, our results suggested founder effects were not mitigated by treatment area or connectivity. Dispersal is negatively density-dependent in D. spectabilis, and we hypothesize that high gene flow may occur early in the restoration trajectory when density is low. Our study shows genetic diversity can be recovered more rapidly than demographic components of populations after habitat restoration and that founder effects are not inevitable for animals colonizing restored habitat in fragmented landscapes. © 2015 John Wiley & Sons Ltd.

Population density of Sotalia guianensis (Cetacea: Delphinidae) in the Cananéia region, Southeastern Brazil.

PubMed

Havukainen, Liisa; Monteiro, Emygdio Leite de Araujo Fiho; Filla, Gislaine de Fatima

2011-09-01

Population density in cetaceans can be estimated through photo-identification, mark-recapture, land-based observations and visual estimative. We the aim to contribute with conservation strategies, we used line transects (distance method) to estimate the population density of the river dolphin, S. guianensis, in the estuarine region of Cananéia, Southeastern Brazil. The study, developed from May 2003 until April 2004, during dry and rainy seasons and different times of the day, included a sampling area divided into three sectors according to their proximity to the open sea: Sector I (the closest to the open sea); Sector II (with a large flow of fresh water and a salient declivity); and Sector III (with a large flow of fresh water and non salient declivity). Onboard random sampling was carried out in all three sectors, and dolphins seen from the bow to 90 degrees on both port and starboard sides, were registered along with their position and distance from the boat. The total density found was 12.41 ind/km2 (CV = 25.53%) with an average of 2.2 individuals per group for both periods of the day, morning and afternoon. Densities also varied between dry and rainy seasons, being lower in the first with 5.77 ind/km2 (CV = 27.87%) than in the second 20.28 ind/km2 (CV = 31.95%), respectively. Regarding the three sectors, a non-causal heterogeneous distribution was found: Sector I was the most populated (D = 33.10 ind/km2, CV = 13.34%), followed by Sector II (D = 7.8 ind/km2, CV = 21.07%) and Sector III (D = 3.04 ind/km2, CV = 34.04%). The aforementioned area, due to its proximity to the open sea, has the highest salinity level and therefore has the greatest chance of holding most of the marine fish schools which can be cornered by dolphins on high declivity areas during fishing activities. This suggests that food availability may be the most important factor on the river dolphin's distribution in the estuary. Similar studies will contribute to a better understanding of these populations and are essential for future conservation strategies.

An adaptive two-stage sequential design for sampling rare and clustered populations

USGS Publications Warehouse

Brown, J.A.; Salehi, M.M.; Moradi, M.; Bell, G.; Smith, D.R.

2008-01-01

How to design an efficient large-area survey continues to be an interesting question for ecologists. In sampling large areas, as is common in environmental studies, adaptive sampling can be efficient because it ensures survey effort is targeted to subareas of high interest. In two-stage sampling, higher density primary sample units are usually of more interest than lower density primary units when populations are rare and clustered. Two-stage sequential sampling has been suggested as a method for allocating second stage sample effort among primary units. Here, we suggest a modification: adaptive two-stage sequential sampling. In this method, the adaptive part of the allocation process means the design is more flexible in how much extra effort can be directed to higher-abundance primary units. We discuss how best to design an adaptive two-stage sequential sample. ?? 2008 The Society of Population Ecology and Springer.

Impact of land use and land cover changes on the ambient temperature in a middle scale city, Takamatsu, in Southwest Japan.

PubMed

Nonomura, Atsuko; Kitahara, Mutsuko; Takuro Masuda

2009-08-01

There is a lack of information on urban heat island impact on the thermal environment due to low populated urban sprawl, although densely populated urban sprawl impact has been identified by several researchers. The Takamatsu area has recently developed in a low populated urban sprawl style without any increase in population. This paper examined the impact of a low populated urban sprawl on the thermal environment through an analysis of the last 30 years data set and investigated the contribution of vegetation fraction and population density to the temperature trend. As a consequence, it was shown that one of the most significant causative factors of temperature increase is an expansion of non-vegetated area even without population growth. This result implied that vegetated zones should be maintained in urban areas in order to realize sustainable urbanization.

Population influences on tornado reports in the United States

USGS Publications Warehouse

Anderson, C.J.; Wikle, C.K.; Zhou, Q.; Royle, J. Andrew

2007-01-01

The number of tornadoes reported in the United States is believed to be less than the actual incidence of tornadoes, especially prior to the 1990s, because tornadoes may be undetectable by human witnesses in sparsely populated areas and areas in which obstructions limit the line of sight. A hierarchical Bayesian model is used to simultaneously correct for population-based sampling bias and estimate tornado density using historical tornado report data. The expected result is that F2-F5 compared with F0-F1 tornado reports would vary less with population density. The results agree with this hypothesis for the following population centers: Atlanta, Georgia; Champaign, Illinois; and Des Moines, Iowa. However, the results indicated just the opposite in Oklahoma. It is hypothesized that the result is explained by the misclassification of tornadoes that were worthy of F2-F5 rating but were classified as F0-F1 tornadoes, thereby artificially decreasing the number of F2-F5 and increasing the number of F0-F1 reports in rural Oklahoma.

Habitat and fish population in the deep-sea Oculina coral ecosystem of the western Atlantic

USGS Publications Warehouse

2005-01-01

In this paper, we describe results from mapping studies conducted in 2001 and improvements to reef fish populations that have occurred in the last few years. We find that less than 10% of the area contains intact Oculina coral thickets, which we continue to attribute primarily to trawling. In addition, we find increased grouper density and male abundance inside the protected area, suggesting population recovery, and the appearance of juvenile speckled hind Epinephelus drummondhayi (family Serranidae), suggesting nursery function for this and possibly other commercially important species.

Impact of density-dependent migration flows on epidemic outbreaks in heterogeneous metapopulations

NASA Astrophysics Data System (ADS)

Ripoll, J.; Avinyó, A.; Pellicer, M.; Saldaña, J.

2015-08-01

We investigate the role of migration patterns on the spread of epidemics in complex networks. We enhance the SIS-diffusion model on metapopulations to a nonlinear diffusion. Specifically, individuals move randomly over the network but at a rate depending on the population of the departure patch. In the absence of epidemics, the migration-driven equilibrium is described by quantifying the total number of individuals living in heavily or lightly populated areas. Our analytical approach reveals that strengthening the migration from populous areas contains the infection at the early stage of the epidemic. Moreover, depending on the exponent of the nonlinear diffusion rate, epidemic outbreaks do not always occur in the most populated areas as one might expect.

Clinical application of dual photon absorptiometry (DPA) at the lumbar spine (LS) in the diagnosis of osteoporosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahner, H.W.; Dunn, W.L.; Riggs, B.L.

This study evaluates the effectiveness of DPA to separate patients with osteoporosis (greater than 2 spinal fractures, normal Ca, P, absence of drugs, and metabolic bone disease) from a normal population. Performance criteria for the instrument have been described previously. Data was obtained from a prospective study of 105 normal women, 75 patients with osteoporosis and a retrospective study of 300 patients with osteoporosis seen in 1982/83. The results were as follows: (1) Area density (gm/cm/sup 2/) was found superior to mass (gm) due to the occasional problem to clearly identify the boundaries of L1-4. (2) Separation of the twomore » populations was best when L1-L4,L2-L4, L3 alone or 10 paths over the mid lumbar area were used. One pass was not acceptable. (3) Compression fractures (CF) in the LS showed an increase in area density initially but area density may be undistinguishable from intact vertebrae later. To correct for this loss of bone area a factor predicting the area of lumbar vertebrae and based on patients actual height and weight was introduced and tested. (4) In the retrospective study a negative correlation was found between number of thoracic spine CF and bone mineral values in the LS. (5) A fracture threshold value of BM defined as the level below which 95% of all patients with CF were found was determined to be 0.98 g/cm2. Sixty-five percent of patients with two or more spinal CF could be separated from the normal population (outside 2SD). By using a correction factor for height loss this could be further increased to about 70%. CF in the LS may falsely elevate bone mineral values.« less

Maximizing Information Yield From Pheromone-Baited Monitoring Traps: Estimating Plume Reach, Trapping Radius, and Absolute Density of Cydia pomonella (Lepidoptera: Tortricidae) in Michigan Apple

PubMed Central

Adams, C. G.; Schenker, J. H.; McGhee, P. S.; Gut, L. J.; Brunner, J. F.

2017-01-01

Abstract Novel methods of data analysis were used to interpret codling moth (Cydia pomonella) catch data from central-trap, multiple-release experiments using a standard codlemone-baited monitoring trap in commercial apple orchards not under mating disruption. The main objectives were to determine consistency and reliability for measures of: 1) the trapping radius, composed of the trap’s behaviorally effective plume reach and the maximum dispersive distance of a responder population; and 2) the proportion of the population present in the trapping area that is caught. Two moth release designs were used: 1) moth releases at regular intervals in the four cardinal directions, and 2) evenly distributed moth releases across entire approximately 18-ha orchard blocks using both high and low codling moth populations. For both release designs, at high populations, the mean proportion catch was 0.01, and for the even release of low populations, that value was approximately 0.02. Mean maximum dispersive distance for released codling moth males was approximately 260 m. Behaviorally effective plume reach for the standard codling moth trap was < 5 m, and total trapping area for a single trap was approximately 21 ha. These estimates were consistent across three growing seasons and are supported by extraordinarily high replication for this type of field experiment. Knowing the trapping area and mean proportion caught, catch number per single monitoring trap can be translated into absolute pest density using the equation: males per trapping area = catch per trapping area/proportion caught. Thus, catches of 1, 3, 10, and 30 codling moth males per trap translate to approximately 5, 14, 48, and 143 males/ha, respectively, and reflect equal densities of females, because the codling moth sex ratio is 1:1. Combined with life-table data on codling moth fecundity and mortality, along with data on crop yield per trapping area, this fundamental knowledge of how to interpret catch numbers will enable pest managers to make considerably more precise projections of damage and therefore more precise and reliable decisions on whether insecticide applications are justified. The principles and methods established here for estimating absolute codling moth density may be broadly applicable to pests generally and thereby could set a new standard for integrated pest management decisions based on trapping. PMID:28131989

Density-dependent vulnerability of forest ecosystems to drought

Treesearch

Alessandra Bottero; Anthony W. D' Amato; Brian J. Palik; John B. Bradford; Shawn Fraver; Mike A. Battaglia; Lance A. Asherin; Harald Bugmann

2017-01-01

Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a given area, is a primary...

Camera trapping estimates of density and survival of fishers (Martes pennanti)

Treesearch

Mark J. Jordan; Reginald H. Barrett; Kathryn L. Purcell

2011-01-01

Developing efficient monitoring strategies for species of conservation concern is critical to ensuring their persistence. We have developed a method using camera traps to estimate density and survival in mesocarnivores and tested it on a population of fishers Martes pennanti in an area of approximately 300 km2 of the southern...

A hierarchical model for spatial capture-recapture data

USGS Publications Warehouse

Royle, J. Andrew; Young, K.V.

2008-01-01

Estimating density is a fundamental objective of many animal population studies. Application of methods for estimating population size from ostensibly closed populations is widespread, but ineffective for estimating absolute density because most populations are subject to short-term movements or so-called temporary emigration. This phenomenon invalidates the resulting estimates because the effective sample area is unknown. A number of methods involving the adjustment of estimates based on heuristic considerations are in widespread use. In this paper, a hierarchical model of spatially indexed capture recapture data is proposed for sampling based on area searches of spatial sample units subject to uniform sampling intensity. The hierarchical model contains explicit models for the distribution of individuals and their movements, in addition to an observation model that is conditional on the location of individuals during sampling. Bayesian analysis of the hierarchical model is achieved by the use of data augmentation, which allows for a straightforward implementation in the freely available software WinBUGS. We present results of a simulation study that was carried out to evaluate the operating characteristics of the Bayesian estimator under variable densities and movement patterns of individuals. An application of the model is presented for survey data on the flat-tailed horned lizard (Phrynosoma mcallii) in Arizona, USA.

Climatic factors and population density of Lutzomyia longipalpis (Lutz & Neiva, 1912) in an urban endemic area of visceral leishmaniasis in midwest Brazil.

PubMed

de Oliveira, Everton Falcão; dos Santos Fernandes, Carlos Eurico; Araújo e Silva, Elaine; Brazil, Reginaldo Peçanha; de Oliveira, Alessandra Gutierrez

2013-12-01

The life cycle of vectors and the reservoirs that participate in the chain of infectious diseases have a strong relationship with the environmental dynamics of the ecosystems in which they live. Oscillations in population abundance and seasonality of insects can be explained by factors inherent in each region and time period. Therefore, knowledge of the relationship and influence of environmental factors on the population of Lutzomyia longipalpis is necessary because of the high incidence of visceral leishmaniasis (VL) in Brazil. This study evaluates the influence of abiotic variables on the population density and seasonal behavior of L. longipalpis in an urban endemic area of VL in Brazil. The sand fly captures were performed every two months between November, 2009 and November, 2010 in the peridomicile of 13 randomly selected residences. We captured 1,367 specimens of L. longipalpis, and the ratio of male/female flies was 2.86:1. The comparison of the total male specimens in the two seasons showed a statistical difference in the wet season, but there was no significant difference when considering the total females. With respect to climatic variables, a significant negative association was observed only with wind speed. During periods of high wind speeds, the population density of this vector decreased. The presence of L. longipalpis was found in all months of the study with bimodal behavior and population peaks during the wet season. © 2013 The Society for Vector Ecology.

Complex life cycles and density dependence: assessing the contribution of egg mortality to amphibian declines.

PubMed

Vonesh, James R; De la Cruz, Omar

2002-11-01

In the last decade there has been increasing evidence of amphibian declines from relatively pristine areas. Some declines are hypothesized to be the result of egg mortality caused by factors such as elevated solar UV-B irradiation, chemical pollutants, pathogenic fungi, and climate change. However, the population-level consequences of egg mortality have not been examined explicitly, and may be complicated by density dependence in intervening life-history stages. Here we develop a demographic model for two amphibians with contrasting life-history strategies, Bufo boreas and Ambystoma macrodactylum. We then use the complementary approaches of elasticity and limitation to examine the relationships among stage-specific survival rates, larval-stage density dependence and amphibian population dynamics. Elasticity analyses showed that for a range of density dependence scenarios both species were more sensitive to changes in post-embryonic survival parameters, particularly juvenile survival, than to egg survival, suggesting that mortality of later stages may play an important role in driving declines. Limitation analyses revealed that larval density dependence can dramatically alter the consequences of early mortality, reducing or even reversing the expected population-level effects of egg mortality. Thus, greater focus on later life stages and density dependence is called for to accurately assess how stressors are likely to affect amphibian populations of conservation concern.

[Density, size structure and reproductive activity of the pink conch Eustrombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, Mexico].

PubMed

Cala, Yuself R; Navarrete, Alberto de Jesús; Ocaña, Frank A; Rivera, José Oliva

2013-12-01

The pink conch Eustrombus gigas is an important fisheries resource. At the regional level in the Caribbean, over-exploitation and habitat destruction have caused a decrease in the abundance of this resource. In order to provide necessary information for the species management in Mexico, this work aimed to analyze the total density, adult density, size structure and reproductive behavior of pink conch population at Banco Chinchorro during 2009-2010. Data from three seasons were obtained (rainy, dry and cold fronts periods) in three areas: Norte (North), Centro (Center) and Sur (South). The organisms were separated into two groups: (a) the criteria based upon legal harvest in Mexico: legal size conchs (siphonal length > 200 mm) and illegal size conchs (siphonal length < 200 mm), and (b) the criteria based upon sexual maturity using the 15 mm lip thickness standard: lip < 15 mm as juvenile conch and lip > or = 15 mm as adult conch. Copulation, spawning, egg masses and aggregations were evaluated as reproductive evidences. The highest total density was observed during the dry season with 384ind./ha, and the lowest during the rainy season with 127ind./ha. The highest density was reported at Sur (385ind./ha) and the lowest at Norte (198ind./ ha). The highest adult density was observed during the rainy season (8.33ind./ha), and the lowest occurred in the dry season (6.1 ind./ha). Adult density values were 5.55, 7.05 and 8.33ind./ha for Centro, Sur and Norte areas, respectively. Adult densities were lower than the threshold needed for reproduction, and 42% of the population may be vulnerable to fishing, as they had the minimum size for catch (Lsi 200 mm). Furthermore, only 2.2% of the population reached a Gl > 15 mm as sexual maturity indicator. During the study period, only six evidences of reproductive activity were observed. The smaller densities reported at Banco Chinchorro may cause reproduction events to be almost absent which in turn is sufficient evidence to show that the Allee Effect is acting on the queen conch population and there is an urgent need of fishery closure. Three important points were proposed for management of queen conch at Banco Chinchorro: total closure of fishing, systematic assessment of the conch population and the implementation of conch fishing refuge.

Mapping of Vegetation with the Geoinformation System and Determining of Carrying Capacity of the Pre-Urals Steppe area for a Newly Establishing Population of the Przewalski Horse Equus ferus przewalskii at the Orenburg State Nature Reserve

NASA Astrophysics Data System (ADS)

Fedorov, N. I.; Mikhailenko, O. I.; Zharkikh, T. L.; Bakirova, R. T.

2018-01-01

Mapping of the vegetation (1:25000) of the Pre-Urals Steppe area at the Orenburg State Nature Reserve was completed in 2016. A map created with the geoinformation system contains 1931 simple and complex polygons for 25 types of vegetation. In a drought year, the average stock of palatable vegetation of the whole area is estimated at 8380 tons dry weight. The estimation is based on the size of areas covered by different types of vegetation, their grass production, the correction coefficients for decreasing of pasture forage stocks in winter and decreasing of production of grass communities in dry years. Based on pasture forage stocks the area could tolerate the maximum population size of 1769 individuals of the Przewalski horse, their average density could be 0.11 horse per ha. Yet, as watering places for animals are limited in Pre-Urals Steppe, grazing pressures on the vegetation next to the water sources may increase in dry years. That is why the above-mentioned calculated maximum population size and density must be reduced at least by half until some additional watering places are established and monitoring of the grazing effect on the vegetation next to the places is carried out regularly. Thus, the maximum size of the population is estimated at 800 to 900 individuals, which is almost 1.5 times more than necessary to establish a self-sustained population of the Przewalski horse.

Does Historical Urban Density Explain the Variation in Per Capita Carbon Dioxide Emissions Across U.S. Cities?

NASA Astrophysics Data System (ADS)

Campbell, K. B.

2013-12-01

The shape a city takes can have long-term impacts. The built environment is durable, and urban infrastructure is costly to alter post-construction, so decisions made early in a city's history have a lasting effect. Cities are some of the biggest aggregate sources of CO2 emissions but are also the areas with the lowest per capita emissions. Even though per capita emissions in urban areas are less than their rural counterparts, the variation in emissions across cities is drastic and understanding this variation can improve the way we build and plan cities. Research has been conducted on how density correlates with per capita emissions, but little has been done on how historical growth has influenced emissions. Using historical census data and the Vulcan Project's fossil fuel CO2 emissions data product, I investigate in greater detail whether historical population density in U.S. cities has had a significant impact on future CO2 emissions in the urban area and in the surrounding region. The census data includes all places that have reported a population of over 100,000 people in any decennial census between 1790 and 2000 and the land area the year that the city first crosses that 100,000-population threshold. This data is used to create the historical density measure. The Vulcan CO2 emissions data is broken down by sector. For this project I use the residential, commercial, and transportation (on road and non-road) emissions sectors on a 10x10km grid in 2002. I also control for regional variation in heating and cooling days, current urban density, average house age, median income, and variation in residential heating (gas, electric, fuel oil, and coal) as these are all known correlates of carbon dioxide emissions. Understanding if historical density better explains the variation in per capita carbon dioxide emissions across cities will help urban planners and city governments decide if it is appropriate to regulate growth during the initial boom of a city, a regulation that can be costly.

Integrating population dynamics into mapping human exposure to seismic hazard

NASA Astrophysics Data System (ADS)

Freire, S.; Aubrecht, C.

2012-11-01

Disaster risk is not fully characterized without taking into account vulnerability and population exposure. Assessment of earthquake risk in urban areas would benefit from considering the variation of population distribution at more detailed spatial and temporal scales, and from a more explicit integration of this improved demographic data with existing seismic hazard maps. In the present work, "intelligent" dasymetric mapping is used to model population dynamics at high spatial resolution in order to benefit the analysis of spatio-temporal exposure to earthquake hazard in a metropolitan area. These night- and daytime-specific population densities are then classified and combined with seismic intensity levels to derive new spatially-explicit four-class-composite maps of human exposure. The presented approach enables a more thorough assessment of population exposure to earthquake hazard. Results show that there are significantly more people potentially at risk in the daytime period, demonstrating the shifting nature of population exposure in the daily cycle and the need to move beyond conventional residence-based demographic data sources to improve risk analyses. The proposed fine-scale maps of human exposure to seismic intensity are mainly aimed at benefiting visualization and communication of earthquake risk, but can be valuable in all phases of the disaster management process where knowledge of population densities is relevant for decision-making.

Greater sage-grouse population trends across Wyoming

USGS Publications Warehouse

Edmunds, David; Aldridge, Cameron L.; O'Donnell, Michael; Monroe, Adrian

2018-01-01

The scale at which analyses are performed can have an effect on model results and often one scale does not accurately describe the ecological phenomena of interest (e.g., population trends) for wide-ranging species: yet, most ecological studies are performed at a single, arbitrary scale. To best determine local and regional trends for greater sage-grouse (Centrocercus urophasianus) in Wyoming, USA, we modeled density-independent and -dependent population growth across multiple spatial scales relevant to management and conservation (Core Areas [habitat encompassing approximately 83% of the sage-grouse population on ∼24% of surface area in Wyoming], local Working Groups [7 regional areas for which groups of local experts are tasked with implementing Wyoming's statewide sage-grouse conservation plan at the local level], Core Area status (Core Area vs. Non-Core Area) by Working Groups, and Core Areas by Working Groups). Our goal was to determine the influence of fine-scale population trends (Core Areas) on larger-scale populations (Working Group Areas). We modeled the natural log of change in population size ( peak M lek counts) by time to calculate the finite rate of population growth (λ) for each population of interest from 1993 to 2015. We found that in general when Core Area status (Core Area vs. Non-Core Area) was investigated by Working Group Area, the 2 populations trended similarly and agreed with the overall trend of the Working Group Area. However, at the finer scale where Core Areas were analyzed separately, Core Areas within the same Working Group Area often trended differently and a few large Core Areas could influence the overall Working Group Area trend and mask trends occurring in smaller Core Areas. Relatively close fine-scale populations of sage-grouse can trend differently, indicating that large-scale trends may not accurately depict what is occurring across the landscape (e.g., local effects of gas and oil fields may be masked by increasing larger populations). 

Cheetahs and wild dogs show contrasting patterns of suppression by lions.

PubMed

Swanson, Alexandra; Caro, Tim; Davies-Mostert, Harriet; Mills, Michael G L; Macdonald, David W; Borner, Markus; Masenga, Emmanuel; Packer, Craig

2014-11-01

Top predators can dramatically suppress populations of smaller predators, with cascading effects throughout communities, and this pressure is often unquestioningly accepted as a constraint on mesopredator populations. In this study, we reassess whether African lions suppress populations of cheetahs and African wild dogs and examine possible mechanisms for coexistence between these species. Using long-term records from Serengeti National Park, we tested 30 years of population data for evidence of mesopredator suppression, and we examined six years of concurrent radio-telemetry data for evidence of large-scale spatial displacement. The Serengeti lion population nearly tripled between 1966 and 1998; during this time, wild dogs declined but cheetah numbers remained largely unchanged. Prior to their local extinction, wild dogs primarily occupied low lion density areas and apparently abandoned the long-term study area as the lion population 'saturated' the region. In contrast, cheetahs mostly utilized areas of high lion density, and the stability of the cheetah population indicates that neither high levels of lion-inflicted mortality nor behavioural avoidance inflict sufficient demographic consequences to translate into population-level effects. Population data from fenced reserves in southern Africa revealed a similar contrast between wild dogs and cheetahs in their ability to coexist with lions. These findings demonstrate differential responses of subordinate species within the same guild and challenge a widespread perception that lions undermine cheetah conservation efforts. Paired with several recent studies that document fine-scale lion-avoidance by cheetahs, this study further highlights fine-scale spatial avoidance as a possible mechanism for mitigating mesopredator suppression. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Density, Demography, and Influential Environmental Factors on Overwintering Populations of Sogatella furcifera (Hemiptera: Delphacidae) in Southern Yunnan, China

PubMed Central

Hu, Shao-Ji; Fu, Da-Ying; Han, Zhong-Liang; Ye, Hui

2015-01-01

Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) is the most serious pest on rice in southwestern China. Yunnan province is within this region and is a major overwintering area for S. furcifera in China. This field study was carried out over 4 yr (2010–2013) and focused on S. furcifera distribution, population density, and demography, as well as the relationship between various environmental factors and the distribution and density of overwintering S. furcifera in Yunnan. Our study demonstrated that overwintering populations of S. furcifera mainly occurred in valleys and lowlands below 25.02°N and 1,680 m above sea level (a.s.l.), where ratooning rice was present. The overwintering range of S. furcifera has expanded in Yunnan compared with 20 yr ago, and regional climate change is believed to be the main contributing cause for this expansion. Environmental factor analysis showed that the mean air temperature of the coldest quarter and precipitation of the coldest quarter were two key factors that were strongly linked to the overwintering distribution and density of S. furcifera in Yunnan. Wintertime temperature was the principal influencing factor to determine the distribution and density of S. furcifera, while the effect of precipitation was indirect in that it influenced the insect’s distribution via its host. This study documented the major overwintering areas of S. furcifera in Yunnan, which can be used to predict outbreak potential in the following spring. Hence, key climatic factors, overwintering distribution, and density of S. furcifera should be used when forecasting outbreaks in spring. PMID:25978998

DS — Software for analyzing data collected using double sampling

USGS Publications Warehouse

Bart, Jonathan; Hartley, Dana

2011-01-01

DS analyzes count data to estimate density or relative density and population size when appropriate. The software is available at http://iwcbm.dev4.fsr.com/IWCBM/default.asp?PageID=126. The software was designed to analyze data collected using double sampling, but it also can be used to analyze index data. DS is not currently configured to apply distance methods or methods based on capture-recapture theory. Double sampling for the purpose of this report means surveying a sample of locations with a rapid method of unknown accuracy and surveying a subset of these locations using a more intensive method assumed to yield unbiased estimates. "Detection ratios" are calculated as the ratio of results from rapid surveys on intensive plots to the number actually present as determined from the intensive surveys. The detection ratios are used to adjust results from the rapid surveys. The formula for density is (results from rapid survey)/(estimated detection ratio from intensive surveys). Population sizes are estimated as (density)(area). Double sampling is well-established in the survey sampling literature—see Cochran (1977) for the basic theory, Smith (1995) for applications of double sampling in waterfowl surveys, Bart and Earnst (2002, 2005) for discussions of its use in wildlife studies, and Bart and others (in press) for a detailed account of how the method was used to survey shorebirds across the arctic region of North America. Indices are surveys that do not involve complete counts of well-defined plots or recording information to estimate detection rates (Thompson and others, 1998). In most cases, such data should not be used to estimate density or population size but, under some circumstances, may be used to compare two densities or estimate how density changes through time or across space (Williams and others, 2005). The Breeding Bird Survey (Sauer and others, 2008) provides a good example of an index survey. Surveyors record all birds detected but do not record any information, such as distance or whether each bird is recorded in subperiods, that could be used to estimate detection rates. Nonetheless, the data are widely used to estimate temporal trends and spatial patterns in abundance (Sauer and others, 2008). DS produces estimates of density (or relative density for indices) by species and stratum. Strata are usually defined using region and habitat but other variables may be used, and the entire study area may be classified as a single stratum. Population size in each stratum and for the entire study area also is estimated for each species. For indices, the estimated totals generally are only useful if (a) plots are surveyed so that densities can be calculated and extrapolated to the entire study area and (b) if the detection rates are close to 1.0. All estimates are accompanied by standard errors (SE) and coefficients of variation (CV, that is, SE/estimate).

Lying in wait: Limiting factors on a low-density ungulate population and the latent traits that can facilitate escape from them

NASA Astrophysics Data System (ADS)

Joly, Kyle; Craig, Tim; Cameron, Matthew D.; Gall, Adrian E.; Sorum, Mathew S.

2017-11-01

Predation, habitat, hunting, and environmental conditions have all been implicated as regulatory mechanisms in ungulate populations. The low-density equilibrium hypothesis predicts that in low-density populations, predators regulate their prey and that the population will not escape unless predation pressure is eased. We evaluated survival of adult and juvenile moose (Alces alces) in north-central Alaska to determine whether or not the population supported the hypothesis. We instrumented adult male and female moose with radiocollars and used aerial observations to track parturition and subsequent survival of juvenile moose. Generalized linear mixed-effects models were used to assess survival. Adult annual survival rates were high (∼89%), but may be negatively influenced by winter conditions. Migratory status did not affect moose survivorship or productivity. Approximately 60% of the calf crop died before 5 months of age. Productivity was significantly lower in the northern section of the study area where there is less high-quality habitat, suggesting that, even in this low-density population, nutrition could be a limiting factor. It appears that predation on young calves, winter weather, and nutritional constraints may be interacting to limit this population. Latent traits, such as overproduction of calves and migratory behavior, which do not currently enhance fitness, may persist within this population so that individuals with these traits can reap benefits when environmental conditions change.

Density and population viability of coastal marten: a rare and geographically isolated small carnivore

PubMed Central

Green, David S.; Levi, Taal

2018-01-01

Pacific martens (Martes caurina humboldtensis) in coastal forests of Oregon and northern California in the United States are rare and geographically isolated, prompting a petition for listing under the Endangered Species Act. If listed, regulations have the potential to influence land-use decisions on public and private lands, but no estimates of population size, density, or viability of remnant marten populations are available for evaluating their conservation status. We used GPS and VHF telemetry and spatial mark-resight to estimate home ranges, density, and population size of Pacific martens in the Oregon Dunes National Recreation Area, central coast Oregon, USA. We then estimated population viability at differing levels of human-caused mortality (e.g., vehicle mortality). Marten home ranges were small on average (females = 0.8 km2, males 1.5 km2) and density (1.13 martens/1 km2) was the highest reported for North American populations (M. caurina, M. americana). We estimated 71 adult martens (95% CRI [41–87]) across two subpopulations separated by a large barrier (Umpqua River). Using population viability analysis, extinction risk for a subpopulation of 30 martens, approximately the size of the subpopulation south of the Umpqua River, ranged from 32% to 99% with two or three annual human-caused mortalities within 30 years. Absent population expansion, limiting human-caused mortalities will likely have the greatest conservation impact. PMID:29637018

Living on the edge: roe deer (Capreolus capreolus) density in the margins of its geographical range.

PubMed

Valente, Ana M; Fonseca, Carlos; Marques, Tiago A; Santos, João P; Rodrigues, Rogério; Torres, Rita Tinoco

2014-01-01

Over the last decades roe deer (Capreolus capreolus) populations have increased in number and distribution throughout Europe. Such increases have profound impacts on ecosystems, both positive and negative. Therefore monitoring roe deer populations is essential for the appropriate management of this species, in order to achieve a balance between conservation and mitigation of the negative impacts. Despite being required for an effective management plan, the study of roe deer ecology in Portugal is at an early stage, and hence there is still a complete lack of knowledge of roe deer density within its known range. Distance sampling of pellet groups coupled with production and decay rates for pellet groups provided density estimates for roe deer in northeastern Portugal (Lombada National Hunting Area--LNHA, Serra de Montesinho--SM and Serra da Nogueira--SN; LNHA and SM located in Montesinho Natural Park). The estimated roe deer density using a stratified detection function was 1.23/100 ha for LNHA, 4.87/100 ha for SM and 4.25/100 ha in SN, with 95% confidence intervals (CI) of 0.68 to 2.21, 3.08 to 7.71 and 2.25 to 8.03, respectively. For the entire area, the estimated density was about 3.51/100 ha (95% CI - 2.26-5.45). This method can provide estimates of roe deer density, which will ultimately support management decisions. However, effective monitoring should be based on long-term studies that are able to detect population fluctuations. This study represents the initial phase of roe deer monitoring at the edge of its European range and intends to fill the gap in this species ecology, as the gathering of similar data over a number of years will provide the basis for stronger inferences. Monitoring should be continued, although the study area should be increased to evaluate the accuracy of estimates and assess the impact of management actions.

Global effects of local human population density and distance to markets on the condition of coral reef fisheries.

PubMed

Cinner, Joshua E; Graham, Nicholas A J; Huchery, Cindy; Macneil, M Aaron

2013-06-01

Coral reef fisheries support the livelihoods of millions of people but have been severely and negatively affected by anthropogenic activities. We conducted a systematic review of published data on the biomass of coral reef fishes to explore how the condition of reef fisheries is related to the density of local human populations, proximity of the reef to markets, and key environmental variables (including broad geomorphologic reef type, reef area, and net productivity). When only population density and environmental covariates were considered, high variability in fisheries conditions at low human population densities resulted in relatively weak explanatory models. The presence or absence of human settlements, habitat type, and distance to fish markets provided a much stronger explanatory model for the condition of reef fisheries. Fish biomass remained relatively low within 14 km of markets, then biomass increased exponentially as distance from reefs to markets increased. Our results suggest the need for an increased science and policy focus on markets as both a key driver of the condition of reef fisheries and a potential source of solutions. © 2012 Society for Conservation Biology.

Current Status of Mimosa pigra L. Infestation in Peninsular Malaysia

PubMed Central

Mansor, Asyraf; Crawley, Micheal J.

2011-01-01

The status and distribution of Mimosa pigra L., a semi-aquatic invasive species in Peninsular Malaysia, were continuously assessed between 2004 and 2007. This assessment investigated its population stand density and related weed management activities. In total, 106 sites of 6 main habitat types i.e., construction site (CS), dam/ reservoir (DM), forest reserve (FR), plantation (PL), river bank/waterway (RB) and roadside (RD) were assessed, and 55 sites were recorded with M. pigra populations. A CS is the most likely habitat to be infested with M. pigra (16 out of 18 assessed sites have this weed), whereas none of the FR visited were found to harbour M. pigra. In terms of population stand density, 41 populations were in the low range of stand density (individual plant of ≤5 m−2), compared to only 9 populations in the high range of stand density (individual plant of >10 m−2). In general, the current impact of M. pigra infestation on natural habitats is relatively low, as its distribution is only confined to disturbed areas. However, continuous monitoring of this weed species is highly recommended, especially in the riparian zone and wetland habitats. PMID:24575208

Spatial and Temporal Variation in Aedes aegypti and Aedes albopictus (Diptera: Culicidae) Numbers in the Yogyakarta Area of Java, Indonesia, With Implications for Wolbachia Releases.

PubMed

Tantowijoyo, W; Arguni, E; Johnson, P; Budiwati, N; Nurhayati, P I; Fitriana, I; Wardana, S; Ardiansyah, H; Turley, A P; Ryan, P; O'Neill, S L; Hoffmann, A A

2016-01-01

of mosquito vector populations, particularly through Wolbachia endosymbionts. The success of these strategies depends on understanding the dynamics of vector populations. In preparation for Wolbachia releases around Yogyakarta, we have studied Aedes populations in five hamlets. Adult monitoring with BioGent- Sentinel (BG-S) traps indicated that hamlet populations had different dynamics across the year; while there was an increase in Aedes aegypti (L.) and Aedes albopictus (Skuse) numbers in the wet season, species abundance remained relatively stable in some hamlets but changed markedly (>2 fold) in others. Local rainfall a month prior to monitoring partly predicted numbers of Ae. aegypti but not Ae. albopictus. Site differences in population size indicated by BG-S traps were also evident in ovitrap data. Egg or larval collections with ovitraps repeated at the same location suggested spatial autocorrelation (<250 m) in the areas of the hamlets where Ae. aegypti numbers were high. Overall, there was a weak negative association (r<0.43) between Ae. aegypti and Ae. albopictus numbers in ovitraps when averaged across collections. Ae. albopictus numbers in ovitraps and BG-S traps were positively correlated with vegetation around areas where traps were placed, while Ae. aegypti were negatively correlated with this feature. These data inform intervention strategies by defining periods when mosquito densities are high, highlighting the importance of local site characteristics on populations, and suggesting relatively weak interactions between Ae. aegypti and Ae. albopictus. They also indicate local areas within hamlets where consistently high mosquito densities may influence Wolbachia invasions and other interventions.

Understanding spatial connectivity of individuals with non-uniform population density.

PubMed

Wang, Pu; González, Marta C

2009-08-28

We construct a two-dimensional geometric graph connecting individuals placed in space within a given contact distance. The individuals are distributed using a measured country's density of population. We observe that while large clusters (group of individuals connected) emerge within some regions, they are trapped in detached urban areas owing to the low population density of the regions bordering them. To understand the emergence of a giant cluster that connects the entire population, we compare the empirical geometric graph with the one generated by placing the same number of individuals randomly in space. We find that, for small contact distances, the empirical distribution of population dominates the growth of connected components, but no critical percolation transition is observed in contrast to the graph generated by a random distribution of population. Our results show that contact distances from real-world situations as for WIFI and Bluetooth connections drop in a zone where a fully connected cluster is not observed, hinting that human mobility must play a crucial role in contact-based diseases and wireless viruses' large-scale spreading.

Assessment of Wind Home System's Potential in Coastal Areas of Pakistan

NASA Astrophysics Data System (ADS)

Memon, Mujeebudin; Harijan, Khanji; Uqaili, Mohammad Aslam

2007-10-01

About 50 and 90 percent of the total population of rural coastal areas of Sindh and Balochistan provinces respectively have no access to electricity and meet lighting requirements through kerosene and LPG. The population density in rural coastal areas of Sindh and Balochistan provinces is about 100-150 and 10-50 persons per km2 respectively. Extension of existing centralized grid system to rural areas with very low population density and small-scattered loads is economically and technically unfeasible. In this situation, decentralized renewable electricity especially wind power appears to be one of the viable option. This paper presents the assessment of potential of wind home systems (WHS) for rural electrification in coastal areas of Pakistan using the wind speed data recorded by Pakistan Metrological Department (PMD) and power curve of a reference wind turbine. Pakistan has 1050 km long coastline, of which, 250 km is falling in Sindh and 800 km in Balochistan. A 150 Wp wind turbine could generate about 345 kWh and 250 kWh of electricity per year in coastal areas of Sindh and Balochistan respectively, which would be sufficient for meeting the electricity demand of a rural household. The average theoretical potential of WHS in the coastal area of Sindh and Balochistan is about 2245 and 1800 FLH respectively. The total installed capacity and technical potential of WHS in the coastal area of the country has been estimated as 63.75 MW and 135 GWh/year respectively.

Not in wilderness: African vulture strongholds remain in areas with high human density

PubMed Central

Granadeiro, José Pedro; Monteiro, Hamilton; Nuno, Ana; Lecoq, Miguel; Cardoso, Paulo; Regalla, Aissa; Catry, Paulo

2018-01-01

Vultures constitute an important functional group in many ecosystems, providing crucial ecosystem services both in natural and humanized environments. These scavengers are facing massive declines worldwide, but in several African countries virtually nothing is known on populations’ status and threats, hampering the development of adequate conservation strategies. In Guinea-Bissau, globally important populations of Hooded Necrosyrtes monachus and African white-backed vultures Gyps africanus were recently reported. Using the country as a study area, we aim to characterize human-vulture interactions in West Africa applying a multidisciplinary approach. We assessed the status and distribution of vulture populations using data from 1711 km of roadside transects, examined predictors of their distribution, and produced a nationwide population estimate for the Hooded Vulture, using an innovative method based on the relationship between the size of human population in settlements and vulture numbers. We conducted 47 stakeholder interviews to assess perceived roles played by vultures, and to investigate potential anthropogenic threats. Hooded vultures were strongly associated with high human population densities, whereas no relation was found between African white-backed and Rüppell’s vultures and any of the tested predictors, which included cattle density, precipitation and Normalized Difference Vegetation Index, among others. We estimate a national population of 43347 Hooded vultures, the largest population reported in the species range. Respondents were generally aware of the services provided by vultures, especially waste and carcass removal, including in urban areas. Hunting for witchcraft and traditional medicine was the most frequently recognised threat, while poisoning was ranked as having the highest impact. We hypothesise that poisoning-related mortality may be affecting African white-backed and Rüppell’s vultures’ distribution and explain their scarcity in apparently highly suitable habitats. Our results suggest a mutualistic rather than a commensalistic relationship between vultures and humans, with important implications for designing and implementing conservation strategies. PMID:29385172

The survival benefit of dual dispatch of EMS and fire-fighters in out-of-hospital cardiac arrest may differ depending on population density--a prospective cohort study.

PubMed

Nordberg, Per; Jonsson, Martin; Forsberg, Sune; Ringh, Mattias; Fredman, David; Riva, Gabriel; Hasselqvist-Ax, Ingela; Hollenberg, Jacob

2015-05-01

Outcome after out-of-hospital cardiac arrest (OHCA) varies between contexts. Dual dispatching of fire-fighters or police in addition to emergency medical services (EMS) has the potential to increase survival, but the effect in urban vs. rural areas is unknown. The aim of this study was to determine the effects of dual dispatching on response times and outcome in regions with different population density. The study design was a prospective cohort study of EMS-treated OHCAs from 2004 (historical controls, only EMS dispatch) and 2006-2009 (intervention, dual dispatch of EMS and fire-fighters), with data on exact geographical coordinates. Patients were divided into four subgroups depending on population density: rural (<250 persons/km2), suburban (250-2999/km2), urban (3000-5999/km2) and downtown (≥6000/km2). Totally, 2513 OHCAs were included (historical controls, n=571 and intervention, n=1942). Median time to arrival of first unit shortened significantly in all subgroups, ranging from 0.8 to 3.2 min, with the main time gain in the rural area. There were significant differences in 30-day survival between the historical controls vs. the intervention group in the suburban population (3.1% vs. 7.0%, p=0.02) and in downtown (4.1 vs. 14.6, p=0.04). In the urban population the difference was 2.7 vs. 6.9% (p=0.06) and in the rural population (4.7 vs. 5.3, p=0.82). Dual dispatch of fire-fighters and EMS in OHCA significantly reduced response times in all studied regions. The 30-day survival increased significantly in the downtown and suburban populations, while a limited impact was seen in the rural areas. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Assessment of forest fragmentation in southern New England using remote sensing and geographic information systems technology

USGS Publications Warehouse

Vogelmann, James E.

1995-01-01

Spatial patterns and rates of forest fragmentation were assessed using digital remote sensing data for a region in southern New England that included 157 townships in southern New Hampshire and northeastern Massachusetts. The study area has undergone marked population increases over the last several decades. Following classification of 1973 and 1988 Landsat Multispectral Scanner data into forest and nonforest classes, data were incorporated into a geographic information system. The natural logarithms of forest area to perimeter ratios, referred to as the forest continuity index, were used to assess patterns and trends of forest fragmentation across the region Forest continuity index values were extracted from each township for both data sets and compared with population data. Forest continuity index values were found to decrease with increasing population density until about 200 persons per square kilometer, after which the relationship stabilized. With slight population increases at low densities forest continuity index values declined sharply, implying abrupt increases in forest fragmentation. Results from the study indicated good negative correlations (r2 values of 0.81 and 0.77) between the Multispectral Scanner-derived forest continuity index and natural logs of township population density. Socioeconomic indicators such as affluence and commuting patterns did not appear to correlate well with forest fragmentation estimates. Decreases in forest continuity index values occurred throughout much of the study region between 1973 and 1988, suggesting that forest fragmentation is occurring over large regions within the eastern United States. It is technologically feasible to assess patterns and rates of forest fragmentation across much larger areas than analyzed in this study; such analyses would provide useful overviews enabling objective assessment of the magnitude of forest fragmentation.

Human impacts on regional avian diversity and abundance

Treesearch

Christopher A. Lepczyk; Curtis H. Flather; Volker C. Radeloff; Anna M. Pidgeon; Roger B. Hammer; Jianguo Liu

2008-01-01

Patterns of association between humans and biodiversity typically show positive, negative, or negative quadratic relationships and can be described by 3 hypotheses: biologically rich areas that support high human population densities co-occur with areas of high biodiversity (productivity); biodiversity decreases monotonically with increasing human activities (ecosystem...

The Heat Exposure Integrated Deprivation Index (HEIDI): A data-driven approach to quantifying neighborhood risk during extreme hot weather.

PubMed

Krstic, Nikolas; Yuchi, Weiran; Ho, Hung Chak; Walker, Blake B; Knudby, Anders J; Henderson, Sarah B

2017-12-01

Mortality attributable to extreme hot weather is a growing concern in many urban environments, and spatial heat vulnerability indexes are often used to identify areas at relatively higher and lower risk. Three indexes were developed for greater Vancouver, Canada using a pool of 20 potentially predictive variables categorized to reflect social vulnerability, population density, temperature exposure, and urban form. One variable was chosen from each category: an existing deprivation index, senior population density, apparent temperature, and road density, respectively. The three indexes were constructed from these variables using (1) unweighted, (2) weighted, and (3) data-driven Heat Exposure Integrated Deprivation Index (HEIDI) approaches. The performance of each index was assessed using mortality data from 1998-2014, and the maps were compared with respect to spatial patterns identified. The population-weighted spatial correlation between the three indexes ranged from 0.68-0.89. The HEIDI approach produced a graduated map of vulnerability, whereas the other approaches primarily identified areas of highest risk. All indexes performed best under extreme temperatures, but HEIDI was more useful at lower thresholds. Each of the indexes in isolation provides valuable information for public health protection, but combining the HEIDI approach with unweighted and weighted methods provides richer information about areas most vulnerable to heat. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Water quality, physical habitat, and fish community composition in streams in the Twin Cities metropolitan area, Minnesota, 1997-98

USGS Publications Warehouse

Talmage, Philip J.; Lee, Kathy E.; Goldstein, Robert M.; Anderson, Jesse P.; Fallon, James D.

1999-01-01

Water quality, physical habitat, and fish-community composition were characterized at 13 Twin Cities metropolitan area streams during low-flow conditions, September 1997. Fish communities were resampled during September 1998. Sites were selected based on a range of human population density. Nutrient concentrations were generally low, rarely exceeding concentrations found in agricultural streams or water-quality criteria. Seventeen pesticides and five pesticide metabolites were detected, with atrazine being the only pesticide detected at all 13 streams. Colony counts of fecal coliform bacteria ranged from 54 to greater than 11,000 colonies per 100 mL. Instream fish habitat was sparse with little woody debris and few boulders, cobble, or other suitable fish habitat. Thirty-eight species and one hybrid from 10 families were collected. Fish communities were characterized by high percentages of omnivores and tolerant species with few intolerant species. Index of Biotic Integrity scores were low, with most streams rating fair to very poor. Percent impervious surface was positively correlated with sodium and chloride concentrations and human population density, but was negatively correlated with fish species richness and diversity. Urban land use and human population density influence fish communities and water quality in Twin Cities metropolitan area streams. Other factors that may influence fish community composition include percent impervious cover, water chemistry, water temperature, geomorphology, substrate, instream habitat, and migration barriers.

Distribution, population status and trends of kittlitz's murrelet brachyramphus brevirostris in lower cook inlet and kachemak bay, Alaska

USGS Publications Warehouse

Kuletz, Kathy J.; Speckman, Suzann G.; Piatt, John F.; Labunski, E.A.

2011-01-01

Lower Cook Inlet (LCI) in south-central Alaska is unusual among the breeding areas of Kittlitz's Murrelet Brachyramphus brevirostris because of human impacts on the marine and terrestrial environments and because of the lack of tidewater glaciers. In LCI the Kittlitz's Murrelet co-exists with the more abundant Marbled Murrelet, which complicates abundance estimates because of the difficulty of species identification. We compared survey data for an area with overlapping coverage in LCI (Core area) in 1993 (June) and from 1996 to 1999 (July-early August). Within this LCI Core area, the surveys in 1996-1999 estimated ~1600 Kittlitz's Murrelets and ~17 000 Marbled Murrelets, including prorated unidentified murrelets. The Kittlitz's Murrelet population declined between 1993 and 1999 at 26% per annum (84% overall). Simultaneously, Marbled Murrelets declined by 12% per annum (56% overall), though the decline was not statistically significant. Declines were estimated conservatively because the 1993 survey was conducted in June, when both murrelet species are less abundant on the water. We also surveyed Kachemak Bay, a large embayment of LCI, during mid-summer (July) of 2005-2007 and estimated a population of 2047 Kittlitz's Murrelets (SD 1120, n = 3 years) residing primarily in the inner bay. Marbled Murrelets numbered 11 040 (SD 1306) and were found throughout the bay. On one transect set in inner Kachemak Bay, Kittlitz's Murrelet density in late summer (1-16 August) declined 7.5% per annum between 1988 and 2007 (n = 6 years), and Marbled Murrelet density increased 4.9% per annum. On two other transect sets in the inner bay, however, neither murrelet species showed a change in density between 1996 and 2007. Inner Kachemak Bay is a persistent hotspot for Kittlitz's Murrelet and may attract murrelets from LCI and beyond. We recommend monitoring murrelet populations in Kachemak Bay, although Kittlitz's Murrelets likely move between the main body of Cook Inlet and Kachemak Bay, and a complete LCI survey is needed to gauge regional population trends.

Large Impact of Eurasian Lynx Predation on Roe Deer Population Dynamics

PubMed Central

Andrén, Henrik; Liberg, Olof

2015-01-01

The effects of predation on ungulate populations depend on several factors. One of the most important factors is the proportion of predation that is additive or compensatory respectively to other mortality in the prey, i.e., the relative effect of top-down and bottom-up processes. We estimated Eurasian lynx (Lynx lynx) kill rate on roe deer (Capreolus capreolus) using radio-collared lynx. Kill rate was strongly affected by lynx social status. For males it was 4.85 ± 1.30 S.E. roe deer per 30 days, for females with kittens 6.23 ± 0.83 S.E. and for solitary females 2.71 ± 0.47 S.E. We found very weak support for effects of prey density (both for Type I (linear) and Type II (non-linear) functional responses) and of season (winter, summer) on lynx kill rate. Additionally, we analysed the growth rate in a roe deer population from 1985 to 2005 in an area, which lynx naturally re-colonized in 1996. The annual roe deer growth rate was lower after lynx re-colonized the study area, but it was also negatively influenced by roe deer density. Before lynx colonized the area roe deer growth rate was λ = 1.079 (± 0.061 S.E.), while after lynx re-colonization it was λ = 0.94 (± 0.051 S.E.). Thus, the growth rate in the roe deer population decreased by Δλ = 0.14 (± 0.080 S.E.) after lynx re-colonized the study area, which corresponded to the estimated lynx predation rate on roe deer (0.11 ± 0.042 S.E.), suggesting that lynx predation was mainly additive to other mortality in roe deer. To conclude, this study suggests that lynx predation together with density dependent factors both influence the roe deer population dynamics. Thus, both top-down and bottom-up processes operated at the same time in this predator-prey system. PMID:25806949

Mapping Air Population

NASA Astrophysics Data System (ADS)

Peterson, Michael P.; Hunt, Paul; Weiß, Konrad

2018-05-01

"Air population" refers to the total number of people flying above the earth at any point in time. The total number of passengers can then be estimated by multiplying the number of seats for each aircraft by the current seat occupancy rate. Using this method, the estimated air population is determined by state for the airspace over the United States. In the interactive, real-time mapping system, maps are provided to show total air population, the density of air population (air population / area of state), and the ratio of air population to ground population.

A comparative study of volumetric breast density estimation in digital mammography and magnetic resonance imaging: results from a high-risk population

NASA Astrophysics Data System (ADS)

Kontos, Despina; Xing, Ye; Bakic, Predrag R.; Conant, Emily F.; Maidment, Andrew D. A.

2010-03-01

We performed a study to compare methods for volumetric breast density estimation in digital mammography (DM) and magnetic resonance imaging (MRI) for a high-risk population of women. DM and MRI images of the unaffected breast from 32 women with recently detected abnormalities and/or previously diagnosed breast cancer (age range 31-78 yrs, mean 50.3 yrs) were retrospectively analyzed. DM images were analyzed using QuantraTM (Hologic Inc). The MRI images were analyzed using a fuzzy-C-means segmentation algorithm on the T1 map. Both methods were compared to Cumulus (Univ. Toronto). Volumetric breast density estimates from DM and MRI are highly correlated (r=0.90, p<=0.001). The correlation between the volumetric and the area-based density measures is lower and depends on the training background of the Cumulus software user (r=0.73-84, p<=0.001). In terms of absolute values, MRI provides the lowest volumetric estimates (mean=14.63%), followed by the DM volumetric (mean=22.72%) and area-based measures (mean=29.35%). The MRI estimates of the fibroglandular volume are statistically significantly lower than the DM estimates for women with very low-density breasts (p<=0.001). We attribute these differences to potential partial volume effects in MRI and differences in the computational aspects of the image analysis methods in MRI and DM. The good correlation between the volumetric and the area-based measures, shown to correlate with breast cancer risk, suggests that both DM and MRI volumetric breast density measures can aid in breast cancer risk assessment. Further work is underway to fully-investigate the association between volumetric breast density measures and breast cancer risk.

Dust mite, cockroach, cat, and dog allergen concentrations in homes of asthmatic children in the northeastern United States: impact of socioeconomic factors and population density.

PubMed Central

Leaderer, Brian P; Belanger, Kathleen; Triche, Elizabeth; Holford, Theodore; Gold, Diane R; Kim, Young; Jankun, Thomas; Ren, Ping; McSharry Je, Jean-ellen; Platts-Mills, Thomas A E; Chapman, Martin D; Bracken, Michael B

2002-01-01

Home exposures to aeroallergens are an important environmental factor in allergic sensitization and in the development and exacerbation of asthma. We assessed variations in home concentrations of dust mite, cockroach, cat, and dog allergens in dust collected in the main living areas of asthmatics' homes by family income, mother's education, dwelling type, population density, household population density, and ethnicity in Connecticut and south-central Massachusetts. Dust samples were collected at the time of home interview in 999 homes as part of an ongoing longitudinal birth cohort study of 1,002 infants and their asthmatic siblings. The analysis employed lower and upper cut points for group 1 dust mite (> or = 2.0 microg/g and > or = 10 microg/g), cockroach (> or = 1.0 U/g and > or = 4.0 U/g), cat (> or = 1.0 microg/g and > or = 8.0 ug/g), and dog (> or = 2.0 microg/g and > or = 10.0 microg/g) allergens. Subject residences were geocoded to assess population density from the U.S. Census, and multiple logistic regression was used to control for confounding. The portion of homes at the lower cut point for dust mite, cockroach, cat, and dog allergens were 46.9%, 24.9%, 42.2%, and 35.6%, respectively; the upper cut point for each of the allergens was reached in 22.4%, 13.4%, 21.0%, and 22.9% of the homes, respectively. In all, 86.0% of the homes had at least one allergen at the lower cut point, and 58.0% had at least one allergen at the upper cut point. Forty-nine percent of the homes had two or more allergens at the lower cut point, and 19.7% had two or more allergens at the upper cut point. Higher education of the mother, higher household income, living in a single-family home in a less densely populated area with fewer people per room, and being a white household were associated with elevated dust mite, cat, and dog allergens and low cockroach allergen. In contrast, low income, living in a multifamily home in a high population density area with a higher occupancy rate per room, and being a Hispanic or black household were associated with elevated cockroach allergens and low concentrations of dust mite, cat, and dog allergens. Although the presence of an individual allergen is more likely associated with one or more socioeconomic or ethnic factors, most homes typically have multiple allergen burdens in excess of concentrations thought to be associated with sensitization and exacerbation of asthma. Mite and cockroach allergens have distinct and opposite associations with socioeconomic factors and population density. PMID:11940461

Can changes in population mixing and socio-economic deprivation in Cumbria, England explain changes in cancer incidence around Sellafield?

PubMed

McNally, Richard J Q; James, Peter W; Blakey, Karen; Basta, Nermine O; Norman, Paul D; Pearce, Mark S

2017-06-01

Previously excesses in incident cases of leukaemia and non-Hodgkin lymphoma have been observed amongst young people born or resident in Seascale, Cumbria. These excesses have not been seen more recently. It is postulated that the former apparent increased risk was related to 'unusual population mixing', which is not present in recent years. This study investigated changes in measures of population mixing from 1951-2001. Comparisons were made between three specified areas. Area-based measures were calculated (migration, commuting, deprivation, population density). All areas have become more affluent, although Seascale was consistently the most affluent. Seascale has become less densely populated, with less migration into the ward and less diversity with respect to migrants' origin. There have been marked changes in patterns of population mixing throughout Cumbria. Lesser population mixing has been observed in Seascale in recent decades. Changes in pattern and nature of population mixing may explain the lack of recent excesses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatial heterogeneity in the carrying capacity of sika deer in Japan.

PubMed

Iijima, Hayato; Ueno, Mayumi

2016-06-09

Carrying capacity is 1 driver of wildlife population dynamics. Although in previous studies carrying capacity was considered to be a fixed entity, it may differ among locations due to environmental variation. The factors underlying variability in carrying capacity, however, have rarely been examined. Here, we investigated spatial heterogeneity in the carrying capacity of Japanese sika deer ( Cervus nippon ) from 2005 to 2014 in Yamanashi Prefecture, central Japan (mesh with grid cells of 5.5×4.6 km) by state-space modeling. Both carrying capacity and density dependence differed greatly among cells. Estimated carrying capacities ranged from 1.34 to 98.4 deer/km 2 . According to estimated population dynamics, grid cells with larger proportions of artificial grassland and deciduous forest were subject to lower density dependence and higher carrying capacity. We conclude that population dynamics of ungulates may vary spatially through spatial variation in carrying capacity and that the density level for controlling ungulate abundance should be based on the current density level relative to the carrying capacity for each area.

Home Range, Habitat Selection, and Population Dynamics of Southern Flying Squirrels in Managed Forests in Arkansas

Treesearch

James F. Taulman; Kimberly G. Smith

2004-01-01

Abstract After experimental harvests on 18 mature pine-hardwood stands in 6 replicated groups, flying squirrels changed from uniform pre-harvest patterns of nest box use to concentrating on protected greenbelt (GB) areas on harvested stands. Squirrel densities declined on all harvested stands as densities increased on three control stands. Fifty...

Floral display size, conspecific density and florivory affect fruit set in natural populations of Phlox hirsuta, an endangered species

PubMed Central

Ruane, Lauren G.; Rotzin, Andrew T.; Congleton, Philip H.

2014-01-01

Background and Aims Natural variation in fruit and seed set may be explained by factors that affect the composition of pollen grains on stigmas. Self-incompatible species require compatible outcross pollen grains to produce seeds. The siring success of outcross pollen grains, however, can be hindered if self (or other incompatible) pollen grains co-occur on stigmas. This study identifies factors that determine fruit set in Phlox hirsuta, a self-sterile endangered species that is prone to self-pollination, and its associated fitness costs. Methods Multiple linear regressions were used to identify factors that explain variation in percentage fruit set within three of the five known populations of this endangered species. Florivorous beetle density, petal colour, floral display size, local conspecific density and pre-dispersal seed predation were quantified and their effects on the ability of flowers to produce fruits were assessed. Key Results In all three populations, percentage fruit set decreased as florivorous beetle density increased and as floral display size increased. The effect of floral display size on fruit set, however, often depended on the density of nearby conspecific plants. High local conspecific densities offset – even reversed – the negative effects of floral display size on percentage fruit set. Seed predation by mammals decreased fruit set in one population. Conclusions The results indicate that seed production in P. hirsuta can be maximized by selectively augmenting populations in areas containing isolated large plants, by reducing the population sizes of florivorous beetles and by excluding mammals that consume unripe fruits. PMID:24557879

Mapping brucellosis increases relative to elk density using hierarchical Bayesian models

USGS Publications Warehouse

Cross, Paul C.; Heisey, Dennis M.; Scurlock, Brandon M.; Edwards, William H.; Brennan, Angela; Ebinger, Michael R.

2010-01-01

The relationship between host density and parasite transmission is central to the effectiveness of many disease management strategies. Few studies, however, have empirically estimated this relationship particularly in large mammals. We applied hierarchical Bayesian methods to a 19-year dataset of over 6400 brucellosis tests of adult female elk (Cervus elaphus) in northwestern Wyoming. Management captures that occurred from January to March were over two times more likely to be seropositive than hunted elk that were killed in September to December, while accounting for site and year effects. Areas with supplemental feeding grounds for elk had higher seroprevalence in 1991 than other regions, but by 2009 many areas distant from the feeding grounds were of comparable seroprevalence. The increases in brucellosis seroprevalence were correlated with elk densities at the elk management unit, or hunt area, scale (mean 2070 km2; range = [95–10237]). The data, however, could not differentiate among linear and non-linear effects of host density. Therefore, control efforts that focus on reducing elk densities at a broad spatial scale were only weakly supported. Additional research on how a few, large groups within a region may be driving disease dynamics is needed for more targeted and effective management interventions. Brucellosis appears to be expanding its range into new regions and elk populations, which is likely to further complicate the United States brucellosis eradication program. This study is an example of how the dynamics of host populations can affect their ability to serve as disease reservoirs.

Predicting free-space occupancy on novel artificial structures by an invasive intertidal barnacle using a removal experiment.

PubMed

Bracewell, Sally A; Robinson, Leonie A; Firth, Louise B; Knights, Antony M

2013-01-01

Artificial structures can create novel habitat in the marine environment that has been associated with the spread of invasive species. They are often located in areas of high disturbance and can vary significantly in the area of free space provided for settlement of marine organisms. Whilst correlation between the amount of free space available and recruitment success has been shown in populations of several marine benthic organisms, there has been relatively little focus on invasive species, a group with the potential to reproduce in vast numbers and colonise habitats rapidly. Invasion success following different scales of disturbance was examined in the invasive acorn barnacle, Austrominiusmodestus, on a unique art installation located in Liverpool Bay. Population growth and recruitment success were examined by comparing recruitment rates within disturbance clearings of 4 different sizes and by contrasting population development with early recruitment rates over a 10 week period. Disturbed areas were rapidly recolonised and monocultures of A. modestus formed within 6 weeks. The size of patch created during disturbance had no effect on the rate of recruitment, while a linear relationship between recruit density and patch size was observed. Density-dependent processes mediated initial high recruitment resulting in population stability after 8-10 weeks, but densities continued to greatly exceed those reported in natural habitats. Given that artificial structures are likely to continue to proliferate in light of climate change projections, free-space is likely to become more available more frequently in the future supporting the expansion of fast-colonising species.

Reproduction and population dynamics of Mastomys natalensis Smith, 1834 in an agricultural landscape in the Western Usambara Mountains, Tanzania.

PubMed

Makundi, Rhodes H; Massawe, Apia W; Mulungu, Loth S

2007-12-01

The multimammate rat, Mastomys natalensis Smith 1834, is a dominant species in agro-ecosystems in Sub-Saharan Africa, but adapts quickly to changes in non-agricultural landscape, particularly woodlands and forests. In this study we report on reproduction and population dynamics of M. natalensis in deforested high elevation localities in the Usambara Mountains, north-east Tanzania. We conducted Capture-Mark-Recapture studies in 2002-2004, and established that reproduction of M. natalensis takes place in the extended wet season between February and June, and the population density peaks in June-August. Reproduction cease in July to January and population density drops from July onwards. Reproduction and population density fluctuations are linked to the duration and amount of rainfall. In years when rainfall was below average and the wet season was short, the population density was significantly lower (below 10 animals/ha and 60 animals/ha in 2003 and 2004 respectively, compared to >100 animals/ha in 2002 when rainfall was above the seasonal average) (F(df 2,13)= 9.092, p < 0.01 for in between years variations and F(df 12,15)= 5.389, p < 0.01 for effect of cumulative annual rainfall on population density). These densities were much lower than in the lowland savannah habitats in central and southwest Tanzania. A comparison between the farmland/fallow mosaic fields and agro-forestry areas showed higher population densities in the former, which have similarities to the preferred habitats in the lowland savannahs. The increasing abundance of M. natalensis in the Usambara could have some consequences: M. natalensis is major pest and is involved in the plague cycle in the western Usambara Mountains. Mastomys natalensis is also a strong competitor and the impact on endemic rodent species, e.g. Lophuromys flavopunctatus and Praomys delectorum is unknown.

Dog ownership, abundance and potential for bat-borne rabies spillover in Chile.

PubMed

Astorga, F; Escobar, L E; Poo-Muñoz, D A; Medina-Vogel, G

2015-03-01

Rabies is a viral infectious disease that affects all mammals, including humans. Factors associated with the incidence of rabies include the presence and density of susceptible hosts and potential reservoirs. Currently, Chile is declared free of canine-related rabies, but there is an overpopulation of dogs within the country and an emergence of rabies in bats. Our objectives are to determine potential areas for bat-borne rabies spillover into dog populations expressed as a risk map, and to explore some key features of dog ownership, abundance, and management in Chile. For the risk map, our variables included a dog density surface (dog/km(2)) and a distribution model of bat-borne rabies presence. From literature review, we obtained dog data from 112 municipalities, which represent 33% of the total municipalities (339). At country level, based on previous studies the median human per dog ratio was 4.8, with 64% of houses containing at least one dog, and a median of 0.9 dog per house. We estimate a national median of 5.3 dog/km(2), and a median of 3680 dogs by municipality, from which we estimate a total population of 3.5×10(6) owned dogs. The antirabies vaccination presented a median of 21% of dogs by municipality, and 29% are unrestricted to some degree. Human per dog ratio have a significant (but weak) negative association with human density. Unrestricted dogs have a negative association with human density and income, and a positive association with the number of dogs per house. Considering dog density by municipality, and areas of potential bat-borne rabies occurrence, we found that 163 (∼48%) of Chilean municipalities are at risk of rabies spillover from bats to dogs. Risk areas are concentrated in urban settlements, including Santiago, Chile's capital. To validate the risk map, we included cases of rabies in dogs from the last 27 years; all fell within high-risk areas of our map, confirming the assertive risk prediction. Our results suggest that the use of dog population parameters may be informative to determine risk areas for bat-rabies spillover events. In addition, we confirm that dog abundance is a neglected and emerging public health concern in Chile, particularly within urban areas, which deserves prompt intervention. Copyright © 2015. Published by Elsevier B.V.

Laws prohibiting over-the-counter syringe sales to injection drug users: relations to population density, HIV prevalence, and HIV incidence.

PubMed

Friedman, S R; Perlis, T; Des Jarlais, D C

2001-05-01

This study sought to assess relations of laws prohibiting over-the-counter syringe sales (anti-OTC laws) to population prevalence of injection drug users and HIV prevalence or incidence among 96 US metropolitan areas. A cross-sectional analysis was used. Metropolitan areas with anti-OTC laws had a higher mean HIV prevalence (13.8% vs 6.7%) than other metropolitan areas (pseudo-P < .001). In 83 metropolitan areas with HIV prevalence of less than 20%, anti-OTC laws were associated with HIV incidence rates of 1% or greater (pseudo-P < .001). Population proportions of injection drug users did not vary by presence of anti-OTC laws. Anti-OTC laws are not associated with lower population proportions of injection drug users. Laws restricting syringe access are associated with HIV transmission and should be repealed.

40 CFR 35.925-13 - Sewage collection system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... design capacity equivalent to that of the existing system plus a reasonable amount for future growth. For purposes of this section, a community would include any area with substantial human habitation on October... October 18, 1972; (b) The collection system is cost-effective; (c) The population density of the area to...

40 CFR 35.925-13 - Sewage collection system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... design capacity equivalent to that of the existing system plus a reasonable amount for future growth. For purposes of this section, a community would include any area with substantial human habitation on October... October 18, 1972; (b) The collection system is cost-effective; (c) The population density of the area to...

Interpolating a consumption variable for scaling and generalizing potential population pressure on urbanizing natural areas

USGS Publications Warehouse

Varanka, Dalia; Jiang, Bin; Yao, Xiaobai

2010-01-01

Measures of population pressure, referring in general to the stress upon the environment by human consumption of resources, are imperative for environmental sustainability studies and management. Development based on resource consumption is the predominant factor of population pressure. This paper presents a spatial model of population pressure by linking consumption associated with regional urbanism and ecosystem services. Maps representing relative geographic degree and extent of natural resource consumption and degree and extent of impacts on surrounding areas are new, and this research represents the theoretical research toward this goal. With development, such maps offer a visualization tool for planners of various services, amenities for people, and conservation planning for ecologist. Urbanization is commonly generalized by census numbers or impervious surface area. The potential geographical extent of urbanism encompasses the environmental resources of the surrounding region that sustain cities. This extent is interpolated using kriging of a variable based on population wealth data from the U.S. Census Bureau. When overlayed with land-use/land-cover data, the results indicate that the greatest estimates of population pressure fall within mixed forest areas. Mixed forest areas result from the spread of cedar woods in previously disturbed areas where further disturbance is then suppressed. Low density areas, such as suburbanization and abandoned farmland are characteristic of mixed forest areas.

Drinking, driving, and crashing: a traffic-flow model of alcohol-related motor vehicle accidents.

PubMed

Gruenewald, Paul J; Johnson, Fred W

2010-03-01

This study examined the influence of on-premise alcohol-outlet densities and of drinking-driver densities on rates of alcohol-related motor vehicle crashes. A traffic-flow model is developed to represent geographic relationships between residential locations of drinking drivers, alcohol outlets, and alcohol-related motor vehicle crashes. Cross-sectional and time-series cross-sectional spatial analyses were performed using data collected from 144 geographic units over 4 years. Data were obtained from archival and survey sources in six communities. Archival data were obtained within community areas and measured activities of either the resident population or persons visiting these communities. These data included local and highway traffic flow, locations of alcohol outlets, population density, network density of the local roadway system, and single-vehicle nighttime (SVN) crashes. Telephone-survey data obtained from residents of the communities were used to estimate the size of the resident drinking and driving population. Cross-sectional analyses showed that effects relating on-premise densities to alcohol-related crashes were moderated by highway trafficflow. Depending on levels of highway traffic flow, 10% greater densities were related to 0% to 150% greater rates of SVN crashes. Time-series cross-sectional analyses showed that changes in the population pool of drinking drivers and on-premise densities interacted to increase SVN crash rates. A simple traffic-flow model can assess the effects of on-premise alcohol-outlet densities and of drinking-driver densities as they vary across communities to produce alcohol-related crashes. Analyses based on these models can usefully guide policy decisions on the sitting of on-premise alcohol outlets.

Role of Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) in local dengue epidemics in Taiwan.

PubMed

Tsai, Pui-Jen; Teng, Hwa-Jen

2016-11-09

Aedes mosquitoes in Taiwan mainly comprise Aedes albopictus and Ae. aegypti. However, the species contributing to autochthonous dengue spread and the extent at which it occurs remain unclear. Thus, in this study, we spatially analyzed real data to determine spatial features related to local dengue incidence and mosquito density, particularly that of Ae. albopictus and Ae. aegypti. We used bivariate Moran's I statistic and geographically weighted regression (GWR) spatial methods to analyze the globally spatial dependence and locally regressed relationship between (1) imported dengue incidences and Breteau indices (BIs) of Ae. albopictus, (2) imported dengue incidences and BI of Ae. aegypti, (3) autochthonous dengue incidences and BI of Ae. albopictus, (4) autochthonous dengue incidences and BI of Ae. aegypti, (5) all dengue incidences and BI of Ae. albopictus, (6) all dengue incidences and BI of Ae. aegypti, (7) BI of Ae. albopictus and human population density, and (8) BI of Ae. aegypti and human population density in 348 townships in Taiwan. In the GWR models, regression coefficients of spatially regressed relationships between the incidence of autochthonous dengue and vector density of Ae. aegypti were significant and positive in most townships in Taiwan. However, Ae. albopictus had significant but negative regression coefficients in clusters of dengue epidemics. In the global bivariate Moran's index, spatial dependence between the incidence of autochthonous dengue and vector density of Ae. aegypti was significant and exhibited positive correlation in Taiwan (bivariate Moran's index = 0.51). However, Ae. albopictus exhibited positively significant but low correlation (bivariate Moran's index = 0.06). Similar results were observed in the two spatial methods between all dengue incidences and Aedes mosquitoes (Ae. aegypti and Ae. albopictus). The regression coefficients of spatially regressed relationships between imported dengue cases and Aedes mosquitoes (Ae. aegypti and Ae. albopictus) were significant in 348 townships in Taiwan. The results indicated that local Aedes mosquitoes do not contribute to the dengue incidence of imported cases. The density of Ae. aegypti positively correlated with the density of human population. By contrast, the density of Ae. albopictus negatively correlated with the density of human population in the areas of southern Taiwan. The results indicated that Ae. aegypti has more opportunities for human-mosquito contact in dengue endemic areas in southern Taiwan. Ae. aegypti, but not Ae. albopictus, and human population density in southern Taiwan are closely associated with an increased risk of autochthonous dengue incidence.

Study on Karst Rock Desertification by Human-Nature Interaction: A Case Study of Fengshan County of Guangxi, China

NASA Astrophysics Data System (ADS)

Zhou, G.; Su, C.; Zhang, R.; Shi, Y.; Liu, Y.; Ma, Y.

2014-11-01

Rocky desertification is a process of soil erosion leading to the bareness of bedrock, and is a kind of typical natural disaster in karst areas, which seriously constrains the developments of local society and economy. This paper studies the impact of human activities on the changes of rocky desertification. With the interpretation of remote sensing images of Fengshan County, GuangXi, China covering 1990, 1995 and 2005, this paper analyzes the relationship of the changes of social and economic index (including population density, agricultural population, rural per capital net income, and farmland) and the changes of rocky desertification in recent 15 years. The results indicate that: in recent 15 years, the average annual growth rate of rocky desertification, rate of change of population density, agricultural population, rural per capita net income, and farmland area are 8.7375 km2 /year, 0.7 person/km2.year, 1153 person/year, 85 Yuan/year, and -269.1 ha/year, respectively. The first three of social and economic indicators at different degrees of growth, show a positive correlation with rocky desertification change. However, farmland area, which has been diminishing, shows a negative correlation with rocky desertification. The influence of human activities for karst rocky desertification can be regarded as population growth - steep slope reclamation - the destruction of vegetation - erosion - rocky desertification - poverty.

A Study on the Priority Selection of Sediment-related Desaster Evacuation Using Debris Flow Combination Degree of Risk

NASA Astrophysics Data System (ADS)

Woo, C.; Kang, M.; Seo, J.; Kim, D.; Lee, C.

2017-12-01

As the mountainous urbanization has increased the concern about landslides in the living area, it is essential to develop the technology to minimize the damage through quick identification and sharing of the disaster occurrence information. In this study, to establish an effective system of alert evacuation that has influence on the residents, we used the debris flow combination degree of risk to predict the risk of the disaster and the level of damage and to select evacuation priorities. Based on the GIS information, the physical strength and social vulnerability were determined by following the debris flow combination of the risk formula. The results classify the physical strength hazard rating of the debris flow combination of the through the normalization process. Debris flow the estimated residential population included in the damage range of the damage prediction map is based on the area and the unit size data. Prediction of occupant formula was calculated by applying different weighting to the resident population and users, and the result was classified into 5 classes as the debris flow physical strength. The debris flow occurrence physical strength and social and psychological vulnerability were classified into the classifications to be reflected in the debris flow integrated risk map using the matrix technique. In addition, to supplement the risk of incorporation of debris flow, we added weight to disaster vulnerable facilities that require a lot of time and manpower to evacuate. The basic model of welfare facilities was supplemented by using basic data, population density, employment density and GDP. First, evacuate areas with high integrated degree of risk level, and evacuate with consideration of physical class differences if classification difficult because of the same or similar grade among the management areas. When the physical hazard class difference is similar, the population difference of the area including the welfare facility is considered first, and the priority is decided in order of age distribution, population density by period, and class difference of residential facility. The results of this study are expected be used as basic data for establishing a safety net for landslide by evacuation systems for disasters. Keyword: Landslide, Debris flow, Early warning system, evacuation

Density estimates of monarch butterflies overwintering in central Mexico

PubMed Central

Diffendorfer, Jay E.; López-Hoffman, Laura; Oberhauser, Karen; Pleasants, John; Semmens, Brice X.; Semmens, Darius; Taylor, Orley R.; Wiederholt, Ruscena

2017-01-01

Given the rapid population decline and recent petition for listing of the monarch butterfly (Danaus plexippus L.) under the Endangered Species Act, an accurate estimate of the Eastern, migratory population size is needed. Because of difficulty in counting individual monarchs, the number of hectares occupied by monarchs in the overwintering area is commonly used as a proxy for population size, which is then multiplied by the density of individuals per hectare to estimate population size. There is, however, considerable variation in published estimates of overwintering density, ranging from 6.9–60.9 million ha−1. We develop a probability distribution for overwinter density of monarch butterflies from six published density estimates. The mean density among the mixture of the six published estimates was ∼27.9 million butterflies ha−1 (95% CI [2.4–80.7] million ha−1); the mixture distribution is approximately log-normal, and as such is better represented by the median (21.1 million butterflies ha−1). Based upon assumptions regarding the number of milkweed needed to support monarchs, the amount of milkweed (Asclepias spp.) lost (0.86 billion stems) in the northern US plus the amount of milkweed remaining (1.34 billion stems), we estimate >1.8 billion stems is needed to return monarchs to an average population size of 6 ha. Considerable uncertainty exists in this required amount of milkweed because of the considerable uncertainty occurring in overwinter density estimates. Nevertheless, the estimate is on the same order as other published estimates. The studies included in our synthesis differ substantially by year, location, method, and measures of precision. A better understanding of the factors influencing overwintering density across space and time would be valuable for increasing the precision of conservation recommendations. PMID:28462031

Density estimates of monarch butterflies overwintering in central Mexico

USGS Publications Warehouse

Thogmartin, Wayne E.; Diffendorfer, James E.; Lopez-Hoffman, Laura; Oberhauser, Karen; Pleasants, John M.; Semmens, Brice X.; Semmens, Darius J.; Taylor, Orley R.; Wiederholt, Ruscena

2017-01-01

Given the rapid population decline and recent petition for listing of the monarch butterfly (Danaus plexippus L.) under the Endangered Species Act, an accurate estimate of the Eastern, migratory population size is needed. Because of difficulty in counting individual monarchs, the number of hectares occupied by monarchs in the overwintering area is commonly used as a proxy for population size, which is then multiplied by the density of individuals per hectare to estimate population size. There is, however, considerable variation in published estimates of overwintering density, ranging from 6.9–60.9 million ha−1. We develop a probability distribution for overwinter density of monarch butterflies from six published density estimates. The mean density among the mixture of the six published estimates was ∼27.9 million butterflies ha−1 (95% CI [2.4–80.7] million ha−1); the mixture distribution is approximately log-normal, and as such is better represented by the median (21.1 million butterflies ha−1). Based upon assumptions regarding the number of milkweed needed to support monarchs, the amount of milkweed (Asclepias spp.) lost (0.86 billion stems) in the northern US plus the amount of milkweed remaining (1.34 billion stems), we estimate >1.8 billion stems is needed to return monarchs to an average population size of 6 ha. Considerable uncertainty exists in this required amount of milkweed because of the considerable uncertainty occurring in overwinter density estimates. Nevertheless, the estimate is on the same order as other published estimates. The studies included in our synthesis differ substantially by year, location, method, and measures of precision. A better understanding of the factors influencing overwintering density across space and time would be valuable for increasing the precision of conservation recommendations.

Effects of urbanization on benthic macroinvertebrate communities in streams, Anchorage, Alaska

USGS Publications Warehouse

Ourso, Robert T.

2001-01-01

The effect of urbanization on stream macroinvertebrate communities was examined by using data gathered during a 1999 reconnaissance of 14 sites in the Municipality of Anchorage, Alaska. Data collected included macroinvertebrate abundance, water chemistry, and trace elements in bed sediments. Macroinvertebrate relative-abundance data were edited and used in metric and index calculations. Population density was used as a surrogate for urbanization. Cluster analysis (unweighted-paired-grouping method) using arithmetic means of macroinvertebrate presence-absence data showed a well-defined separation between urbanized and nonurbanized sites as well as extracted sites that did not cleanly fall into either category. Water quality in Anchorage generally declined with increasing urbanization (population density). Of 59 variables examined, 31 correlated with urbanization. Local regression analysis extracted 11 variables that showed a significant impairment threshold response and 6 that showed a significant linear response. Significant biological variables for determining the impairment threshold in this study were the Margalef diversity index, Ephemeroptera-Plecoptera-Trichoptera taxa richness, and total taxa richness. Significant thresholds were observed in the water-chemistry variables conductivity, dissolved organic carbon, potassium, and total dissolved solids. Significant thresholds in trace elements in bed sediments included arsenic, iron, manganese, and lead. Results suggest that sites in Anchorage that have ratios of population density to road density greater than 70, storm-drain densities greater than 0.45 miles per square mile, road densities greater than 4 miles per square mile, or population densities greater than 125-150 persons per square mile may require further monitoring to determine if the stream has become impaired. This population density is far less than the 1,000 persons per square mile used by the U.S. Census Bureau to define an urban area.

Space-Time Analyses of Alcohol Outlets and Related Motor Vehicle Crashes: Associations at City and Census Block-Group Levels.

PubMed

Lipton, Robert; Ponicki, William R; Gruenewald, Paul J; Gaidus, Andrew

2018-06-01

Past research has linked alcohol outlet densities to drinking, drunken driving, and alcohol-related motor vehicle crashes (MVCs). Because impaired drivers travel some distances from drinking places to crash locations, spatial relationships between outlets and crashes are complex. We investigate these relationships at 3 geographic levels: census block groups (CBGs), adjacent (nearby) areas, and whole cities. We examined risks of all injury MVCs as well as "had been drinking" (HBD) and single-vehicle-nighttime (SVN) subgroups using data from the Statewide Integrated Traffic Records System across CBGs among 50 California cities from 2001 to 2008. Relationships between outlet densities at the city level, within CBGs, and in adjacent CBGs and crashes were examined using Bayesian Poisson space-time analyses controlling for population size income and other demographics (all as covariates). All injury MVCs were positively related to adjacent CBG population size (relative rate [RR] = 1.008, 95% credible interval (CI) = 1.004, 1.012), and outlet densities at CBG (RR = 1.027, CI = 1.020, 1.035), nearby area (RR = 1.084, CI = 1.060, 1.106) and city levels (RR = 1.227, CI = 1.147, 1.315), and proportion of bars or pubs at the city level (RR = 2.257, CI = 1.187, 4.125). HBD and SVN crashes were comparatively less frequent in high outlet density CBG (RR = 0.993, CI = 0.987, 0.999; RR = 0.963, CI = 0.951, 0.975) and adjacent areas (RR = 0.979, CI = 0.962, 0.996; RR = 0.909, CI = 0.883, 0.936), but positively associated with city-level proportions of bars (RR = 3.373, CI = 0.736, 15.644; RR = 10.322, CI = 1.704, 81.215). Overall, a 10% increase in all outlets was related to 2.8% more injury crashes (CI = 2.3, 3.3) and 2.5% more HBDs (CI = 1.7, 3.3). A 10% increase in bars was related to 1.4% more crashes, 4.3% more HBDs, and 10.3% more SVNs. Population size and densities of bars or pubs were found to be associated with crash rates, with population effects appearing across cities and outlet effects appearing within dense downtown areas. Summary estimates of outlet and population impacts on MVCs must consider varying contributions at multiple spatial scales. Copyright © 2018 by the Research Society on Alcoholism.

Weather-Related Hazards and Population Change: A Study of Hurricanes and Tropical Storms in the United States, 1980–2012

PubMed Central

FUSSELL, ELIZABETH; CURRAN, SARA R.; DUNBAR, MATTHEW D.; BABB, MICHAEL A.; THOMPSON, LUANNE; MEIJER-IRONS, JACQUELINE

2017-01-01

Environmental determinists predict that people move away from places experiencing frequent weather hazards, yet some of these areas have rapidly growing populations. This analysis examines the relationship between weather events and population change in all U.S. counties that experienced hurricanes and tropical storms between 1980 and 2012. Our database allows for more generalizable conclusions by accounting for heterogeneity in current and past hurricane events and losses and past population trends. We find that hurricanes and tropical storms affect future population growth only in counties with growing, high-density populations, which are only 2 percent of all counties. In those counties, current year hurricane events and related losses suppress future population growth, although cumulative hurricane-related losses actually elevate population growth. Low-density counties and counties with stable or declining populations experience no effect of these weather events. Our analysis provides a methodologically informed explanation for contradictory findings in prior studies. PMID:29326480

Weather-Related Hazards and Population Change: A Study of Hurricanes and Tropical Storms in the United States, 1980-2012.

PubMed

Fussell, Elizabeth; Curran, Sara R; Dunbar, Matthew D; Babb, Michael A; Thompson, Luanne; Meijer-Irons, Jacqueline

2017-01-01

Environmental determinists predict that people move away from places experiencing frequent weather hazards, yet some of these areas have rapidly growing populations. This analysis examines the relationship between weather events and population change in all U.S. counties that experienced hurricanes and tropical storms between 1980 and 2012. Our database allows for more generalizable conclusions by accounting for heterogeneity in current and past hurricane events and losses and past population trends. We find that hurricanes and tropical storms affect future population growth only in counties with growing, high-density populations, which are only 2 percent of all counties. In those counties, current year hurricane events and related losses suppress future population growth, although cumulative hurricane-related losses actually elevate population growth. Low-density counties and counties with stable or declining populations experience no effect of these weather events. Our analysis provides a methodologically informed explanation for contradictory findings in prior studies.

Frequently Asked Questions (FAQs) about Malaria

MedlinePlus

... areas tend to have less commercial activity, less population density, more green space, and agriculture ... that no more malaria exists in the world. Malaria has been eliminated from many developed countries ...

Focus for Area Development Analysis: Urban Orientation of Counties.

ERIC Educational Resources Information Center

Bluestone, Herman

The orientation of counties to metropolitan systems and urban centers is identified by population density and percentage of urban population. This analytical framework differentiates 6 kinds of counties, ranging from most urban-oriented (group 1) to least urban-oriented (group 6). With this framework, it can be seen that the economic well-being of…

Effects of egg and hatchling harvest on American alligators in Florida

USGS Publications Warehouse

Rice, K.G.; Percival, H.F.; Woodward, A.R.; Jennings, Michael L.

1999-01-01

Harvest of crocodilian eggs and young for captive rearing (ranching) has been used worldwide as an option for producing crocodilian skins and meat from wild stock. The long-term effects of harvesting a certain proportion of early age class, wild American alligators (Alligator mississippiensis) without repatriation is unknown. We removed an estimated 50% of annual production of alligators on Lakes Griffin and Jesup in central Florida over an 11-year period and monitored population levels via night-light counts. Densities of the total alligator population increased (P 0.117), and subadult (122-182 cm TL) alligators increased (P < 0.011) on harvest areas. The density of juveniles on the control area increased (P = 0.006), and the density of subadults showed some evidence of increasing (P = 0.088). No changes were detected in size distributions on the treatment areas. Nest production, as observed from aerial helicopter surveys, increased (P < 0.039) on Lake Woodruff NWR and Lake Jesup and showed some evidence of an increase on Lake Griffin (P = 0.098) during 1983-91. A 50% harvest rate of eggs or hatchlings did not adversely affect recruitment into the subadult or adult size classes.

Urbanization affects neophilia and risk-taking at bird-feeders

NASA Astrophysics Data System (ADS)

Tryjanowski, Piotr; Møller, Anders Pape; Morelli, Federico; Biaduń, Waldemar; Brauze, Tomasz; Ciach, Michał; Czechowski, Paweł; Czyż, Stanisław; Dulisz, Beata; Goławski, Artur; Hetmański, Tomasz; Indykiewicz, Piotr; Mitrus, Cezary; Myczko, Łukasz; Nowakowski, Jacek J.; Polakowski, Michał; Takacs, Viktoria; Wysocki, Dariusz; Zduniak, Piotr

2016-06-01

Urban environments cover vast areas with a high density of humans and their dogs and cats causing problems for exploitation of new resources by wild animals. Such resources facilitate colonization by individuals with a high level of neophilia predicting that urban animals should show more neophilia than rural conspecifics. We provided bird-feeders across urban environments in 14 Polish cities and matched nearby rural habitats, testing whether the presence of a novel item (a brightly coloured green object made out of gum with a tuft of hair) differentially delayed arrival at feeders in rural compared to urban habitats. The presence of a novel object reduced the number of great tits Parus major, but also the total number of all species of birds although differentially so in urban compared to rural areas. That was the case independent of the potentially confounding effects of temperature, population density of birds, and the abundance of cats, dogs and pedestrians. The number of great tits and the total number of birds attending feeders increased in urban compared to rural areas independent of local population density of birds. This implies that urban birds have high levels of neophilia allowing them to readily exploit unpredictable resources in urban environments.

Population size and density of Colobus vellerosus at the Boabeng-Fiema Monkey Sanctuary and surrounding forest fragments in Ghana.

PubMed

Wong, Sarah N P; Sicotte, Pascale

2006-05-01

The Boabeng-Fiema Monkey Sanctuary (BFMS) is inhabited by a growing population of Ursine colobus (Colobus vellerosus), a species that is listed as vulnerable. Smaller, degraded forest fragments that surround the BFMS also contain C. vellerosus and may provide an important habitat for the monkeys. Our objectives were to 1) determine the current population size and density of C. vellerosus at BFMS and in five surrounding fragments, 2) examine the differences in demographics between the fragments and BFMS, and 3) determine whether a relationship exists between population density and fragment size and isolation distance from BFMS. The census was a complete count and was conducted for 1 month (July 2003) by S.W. and trained research assistants. Seven census routes were walked simultaneously on 13 days. The 2003 population estimate of C. vellerosus at BFMS was 217-241 individuals (15 groups), a slight increase from the 2000 census. Numbers in the fragments (58-62, six groups) have remained stable since 1997, when the only other census of these fragments was conducted. Mean group size did not differ between the fragments and BFMS. Larger fragments had larger numbers of colobus, but there was no relationship between fragment size and colobus density. Isolation distance had no effect on population density. Our data suggest that colobus probably travel between fragments. Conservation efforts should focus on treating the small forests and their connecting areas as a single conservation unit. 2005 Wiley-Liss, Inc.

Spatial and Host-Related Variation in Prevalence and Population Density of Wheat Curl Mite (Aceria tosichella) Cryptic Genotypes in Agricultural Landscapes.

PubMed

Skoracka, Anna; Lewandowski, Mariusz; Rector, Brian G; Szydło, Wiktoria; Kuczyński, Lechosław

2017-01-01

The wheat curl mite (WCM), Aceria tosichella Keifer, is a major pest of cereals worldwide that also comprises a complex of at least 16 genetic lineages with divergent physiological traits, including host associations and specificity. The goal of this study was to test the extent to which host-plant species and landscape spatial variation influence WCM presence and population density across the entire area of Poland (>311,000 km2). Three important findings arose from the results of the study. (1) The majority of WCM lineages analyzed exhibited variation in patterns of prevalence and/or population density on both spatial and host-associated scales. (2) Areas of occurrence and local abundance were delineated for specific WCM lineages and it was determined that the most pestiferous lineages are much less widespread than was expected, suggesting relatively recent introductions into Poland and the potential for further spread. (3) The 16 WCM lineages under study assorted within four discrete host assemblages, within which similar host preferences and host infestation patterns were detected. Of these four groups, one consists of lineages associated with cereals. In addition to improving basic ecological knowledge of a widespread arthropod herbivore, the results of this research identify high-risk areas for the presence of the most pestiferous WCM lineages in the study area (viz. the entirety of Poland). They also provide insight into the evolution of pest species of domesticated crops and facilitate testing of fundamental hypotheses about the ecological factors that shape this pest community.

Spatial and Host-Related Variation in Prevalence and Population Density of Wheat Curl Mite (Aceria tosichella) Cryptic Genotypes in Agricultural Landscapes

PubMed Central

Lewandowski, Mariusz; Rector, Brian G.; Szydło, Wiktoria

2017-01-01

The wheat curl mite (WCM), Aceria tosichella Keifer, is a major pest of cereals worldwide that also comprises a complex of at least 16 genetic lineages with divergent physiological traits, including host associations and specificity. The goal of this study was to test the extent to which host-plant species and landscape spatial variation influence WCM presence and population density across the entire area of Poland (>311,000 km2). Three important findings arose from the results of the study. (1) The majority of WCM lineages analyzed exhibited variation in patterns of prevalence and/or population density on both spatial and host-associated scales. (2) Areas of occurrence and local abundance were delineated for specific WCM lineages and it was determined that the most pestiferous lineages are much less widespread than was expected, suggesting relatively recent introductions into Poland and the potential for further spread. (3) The 16 WCM lineages under study assorted within four discrete host assemblages, within which similar host preferences and host infestation patterns were detected. Of these four groups, one consists of lineages associated with cereals. In addition to improving basic ecological knowledge of a widespread arthropod herbivore, the results of this research identify high-risk areas for the presence of the most pestiferous WCM lineages in the study area (viz. the entirety of Poland). They also provide insight into the evolution of pest species of domesticated crops and facilitate testing of fundamental hypotheses about the ecological factors that shape this pest community. PMID:28099506

Landscape and vegetation effects on avian reproduction on bottomland forest restorations

USGS Publications Warehouse

Twedt, Daniel J.; Somershoe, Scott G.; Hazler, Kirsten R.; Cooper, Robert J.

2010-01-01

Forest restoration has been undertaken on >200,000 ha of agricultural land in the Mississippi Alluvial Valley, USA, during the past few decades. Decisions on where and how to restore bottomland forests are complex and dependent upon landowner objectives, but for conservation of silvicolous (forest-dwelling) birds, ecologists have espoused restoration through planting a diverse mix of densely spaced seedlings that includes fast-growing species. Application of this planting strategy on agricultural tracts that are adjacent to extant forest or within landscapes that are predominately forested has been advocated to increase forest area and enhance forested landscapes, thereby benefiting area-sensitive, silvicolous birds. We measured support for these hypothesized benefits through assessments of densities of breeding birds and reproductive success of 9 species on 36 bottomland forest restoration sites. Densities of thamnic (shrub-scrub dwelling) and silvicolous birds, such as yellow-breasted chat (Icteria virens), indigo bunting (Passerina cyanea), and white-eyed vireo (Vireo griseus) were positively associated with 1) taller trees, 2) greater stem densities, and 3) a greater proportion of forest within the landscape, whereas densities of birds associated with grasslands, such as dickcissel (Spiza americana) and red-winged blackbird (Agelaius phoeniceus), were negatively associated with these variables. Vegetation structure, habitat edge, and temporal effects had greater influence on nest success than did landscape effects. Taller trees, increased density of woody stems, greater vegetation density, and more forest within the landscape were often associated with greater nest success. Nest success of grassland birds was positively related to distance from forest edge but, for thamnic birds, success was greater near edges. Moreover, nest success and estimated fecundity of thamnic species suggested their populations are self-sustaining on forest restoration sites, whereas these sites are likely population sinks for grassland and open-woodland species. We recommend restoration strategies that promote rapid development of dense forest stands within largely forested landscapes to recruit breeding populations of thamnic and silvicolous birds that have reproductive success sufficient to sustain their populations.

Correlates of bushmeat in markets and depletion of wildlife.

PubMed

Fa, John E; Olivero, Jesus; Farfán, Miguel Á; Márquez, Ana L; Duarte, Jesús; Nackoney, Janet; Hall, Amy; Dupain, Jef; Seymour, Sarah; Johnson, Paul J; Macdonald, David W; Real, Raimundo; Vargas, Juan M

2015-06-01

We used data on number of carcasses of wildlife species sold in 79 bushmeat markets in a region of Nigeria and Cameroon to assess whether species composition of a market could be explained by anthropogenic pressures and environmental variables around each market. More than 45 mammal species from 9 orders were traded across all markets; mostly ungulates and rodents. For each market, we determined median body mass, species diversity (game diversity), and taxa that were principal contributors to the total number of carcasses for sale (game dominance). Human population density in surrounding areas was significantly and negatively related to the percentage ungulates and primates sold in markets and significantly and positively related to the proportion of rodents. The proportion of carnivores sold was higher in markets with high human population densities. Proportion of small-bodied mammals (<1 kg) sold in markets increased as human population density increased, but proportion of large-bodied mammals (>10 kg) decreased as human population density increased. We calculated an index of game depletion (GDI) for each market from the sum of the total number of carcasses traded per annum and species, weighted by the intrinsic rate of natural increase (rmax ) of each species, divided by individuals traded in a market. The GDI of a market increased as the proportion of fast-reproducing species (highest rmax ) increased and as the representation of species with lowest rmax (slow-reproducing) decreased. The best explanatory factor for a market's GDI was anthropogenic pressure-road density, human settlements with >3000 inhabitants, and nonforest vegetation. High and low GDI were significantly differentiated by human density and human settlements with >3000 inhabitants. Our results provided empirical evidence that human activity is correlated with more depleted bushmeat faunas and can be used as a proxy to determine areas in need of conservation action. © 2015 Society for Conservation Biology.

A GIS analysis of suitability for construction aggregate recycling sites using regional transportation network and population density features

USGS Publications Warehouse

Robinson, G.R.; Kapo, K.E.

2004-01-01

Aggregate is used in road and building construction to provide bulk, strength, support, and wear resistance. Reclaimed asphalt pavement (RAP) and reclaimed Portland cement concrete (RPCC) are abundant and available sources of recycled aggregate. In this paper, current aggregate production operations in Virginia, Maryland, and the District of Columbia are used to develop spatial association models for the recycled aggregate industry with regional transportation network and population density features. The cost of construction aggregate to the end user is strongly influenced by the cost of transporting processed aggregate from the production site to the construction site. More than 60% of operations recycling aggregate in the mid-Atlantic study area are located within 4.8 km (3 miles) of an interstate highway. Transportation corridors provide both sites of likely road construction where aggregate is used and an efficient means to move both materials and on-site processing equipment back and forth from various work sites to the recycling operations. Urban and developing areas provide a high market demand for aggregate and a ready source of construction debris that may be processed into recycled aggregate. Most aggregate recycling operators in the study area are sited in counties with population densities exceeding 77 people/km2 (200 people/mile 2). No aggregate recycling operations are sited in counties with less than 19 people/km2 (50 people/mile2), reflecting the lack of sufficient long-term sources of construction debris to be used as an aggregate source, as well as the lack of a sufficient market demand for aggregate in most rural areas to locate a recycling operation there or justify the required investment in the equipment to process and produce recycled aggregate. Weights of evidence analyses (WofE), measuring correlation on an area-normalized basis, and weighted logistic regression (WLR), are used to model the distribution of RAP and RPCC operations relative to transportation network and population distribution data. The models can be used on a regional scale to quickly map the relative site suitability for a RAP or RPCC aggregate recycling operation in a particular area based on transportation network and population parameters. The results can be used to identify general areas to be further evaluated on a site-specific basis using more detailed marketplace information. As transportation or population features change due to planning or actual development, the models can be easily revised to reflect these changes. ?? 2004 Elsevier B.V. All rights reserved.

Working with Decision Makers to Improve Energy-Water System Resiliency in the Lower Hudson River Basin

NASA Astrophysics Data System (ADS)

Fellows, J. D.; Schoonen, M. A.; Pullen, J.; González, J. E.; Saleh, F.; Bhatt, V.

2017-12-01

Nearly half of the 180 million people living in the eastern U.S. reside in coastal watershed or shoreline counties. The population density of these areas continues to increase, driving an increase in energy-water (EW) system demand and expansion of critical infrastructure. Along with population, these areas are also being stressed by environmental and technology stresses, including climate change. We have been working with decision makers in the Lower Hudson River Basin (LHRB) to develop the tools and data needed to better understand and improve the resiliency of LHRB EW systems facing these kinds of stresses. The LHRB represents: 1) a coastal environment subject to sea level rise that is among the fastest in the East; 2) one of the steepest gradients in population density in the US, with Manhattan the most densely populated coastal county in the nation; 3) a EWN infrastructure serving the largest metropolitan area in the US and the financial center of the world; 4) a history of environmental impacts, ranging from heatwaves, hurricanes to localized storms, that can be used to hindcast; and 5) a wealth of historic and real-time data, extensive monitoring facilities and existing specific sector models that can be leveraged. This presentation will focus on the lessons learned working with the LHRB decision makers.

Projections of forestland and developed land areas in western Washington.

Treesearch

R. Alig; E. White

2007-01-01

Between 1990 and 2000, nonfederal timberland areas in western Washington declined by 5 percent, in contrast to a 3-percent reduction for the 1980-90 period. Most of this reduction is attributed to the conversion of timberland to other land uses, especially urban and other developed uses. In areas such as the Puget Sound region, population densities have more than...

Do microplastic loads reflect the population demographics along the southern African coastline?

PubMed

Nel, Holly Astrid; Hean, Jeffrey William; Noundou, Xavier Siwe; Froneman, Pierre William

2017-02-15

Plastic pollution is a major anthropogenic contaminant effecting the marine environment and is often associated with high human population densities and industrial activities. The microplastic (63 to 5000μm) burden of beach sediment and surf-zone water was investigated at selected sites along the entire length of the South African coastline. It was predicted that samples collected in areas of high population density, would contain a higher microplastic burden than those along coasts that demonstrate very low population densities. With the exception of water column microplastics within Richard's Bay Harbour (413.3±77.53particles·m -3 ) and Durban Harbour (1200±133.2particles·m -3 ), there were no significant spatial differences in microplastic loads. This supports the theory that harbours act as a source of microplastics for the surrounding marine environment. Additionally, the absence of any spatial variation highlights the possible long range distribution of microplastic pollutants by large scale ocean currents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Human impact on wildfires varies between regions and with vegetation productivity

NASA Astrophysics Data System (ADS)

Lasslop, Gitta; Kloster, Silvia

2017-11-01

We assess the influence of humans on burned area simulated with a dynamic global vegetation model. The human impact in the model is based on population density and cropland fraction, which were identified as important drivers of burned area in analyses of global datasets, and are commonly used in global models. After an evaluation of the sensitivity to these two variables we extend the model by including an additional effect of the cropland fraction on the fire duration. The general pattern of human influence is similar in both model versions: the strongest human impact is found in regions with intermediate productivity, where fire occurrence is not limited by fuel load or climatic conditions. Human effects in the model increases burned area in the tropics, while in temperate regions burned area is reduced. While the population density is similar on average for the tropical and temperate regions, the cropland fraction is higher in temperate regions, and leads to a strong suppression of fire. The model shows a low human impact in the boreal region, where both population density and cropland fraction is very low and the climatic conditions, as well as the vegetation productivity limit fire. Previous studies attributed a decrease in fire activity found in global charcoal datasets to human activity. This is confirmed by our simulations, which only show a decrease in burned area when the human influence on fire is accounted for, and not with only natural effects on fires. We assess how the vegetation-fire feedback influences the results, by comparing simulations with dynamic vegetation biogeography to simulations with prescribed vegetation. The vegetation-fire feedback increases the human impact on burned area by 10% for present day conditions. These results emphasize that projections of burned area need to account for the interactions between fire, climate, vegetation and humans.

Techniques of contributing-area delineation for analysis of nonpoint-source contamination of Long Island, New York

USGS Publications Warehouse

Misut, P.

1995-01-01

Ninety shallow monitoring wells on Long Island, N.Y., were used to test the hypothesis that the correlation between the detection of volatile organic compounds (VOC's) at a well and explanatory variables representing land use, population density, and hydrogeologic conditions around the well is affected by the size and shape of the area defined as the contributing area. Explanatory variables are quantified through overlay of various specified contributing areas on 1:24 000-scale landuse and population-density geographic information system (GIS) coverages. Four methods of contributing-area delineation were used: (a) centering a circle of selected radius on the well site, (b) orienting a triangular area along the direction of horizontal ground-water flow to the well, (c) generating a shaped based on direction and magnitude of horizontal flow to the well, and (d) generating a shape based on three-dimensional particle pathlines backtracked from the well screen to the water table. The strongest correlations with VOC detections were obtained from circles of 400- to 1 000-meter radius. Improvement in correlation through delineations based on ground-water flow would require geographic overlay on more highly detailed GIS coverages than those used in the study.

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density.

PubMed

Froehlich, Catheline Y M; Kline, Richard J

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1-190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71-120 culverts in a 30-m radius to yield the highest fish abundances.

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density

PubMed Central

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1–190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71–120 culverts in a 30-m radius to yield the highest fish abundances. PMID:26422472

Sinks without borders: Snowshoe hare dynamics in a complex landscape

USGS Publications Warehouse

Griffin, Paul C.; Mills, L. Scott

2009-01-01

A full understanding of population dynamics of wide-ranging animals should account for the effects that movement and habitat use have on individual contributions to population growth or decline. Quantifying the per-capita, habitat-specific contribution to population growth can clarify the value of different patch types, and help to differentiate population sources from population sinks. Snowshoe hares, Lepus americanus, routinely use various habitat types in the landscapes they inhabit in the contiguous US, where managing forests for high snowshoe hare density is a priority for conservation of Canada lynx, Lynx canadensis. We estimated density and demographic rates via mark–recapture live trapping and radio-telemetry within four forest stand structure (FSS) types at three study areas within heterogeneous managed forests in western Montana. We found support for known fate survival models with time-varying individual covariates representing the proportion of locations in each of the FSS types, with survival rates decreasing as use of open young and open mature FSS types increased. The per-capita contribution to overall population growth increased with use of the dense mature or dense young FSS types and decreased with use of the open young or open mature FSS types, and relatively high levels of immigration appear to be necessary to sustain hares in the open FSS types. Our results support a conceptual model for snowshoe hares in the southern range in which sink habitats (open areas) prevent the buildup of high hare densities. More broadly, we use this system to develop a novel approach to quantify demographic sources and sinks for animals making routine movements through complex fragmented landscapes.

Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa

PubMed Central

Mecenero, Silvia; Altwegg, Res; Colville, Jonathan F.; Beale, Colin M.

2015-01-01

Wildlife and humans tend to prefer the same productive environments, yet high human densities often lead to reduced biodiversity. Species richness is often positively correlated with human population density at broad scales, but this correlation could also be caused by unequal sampling effort leading to higher species tallies in areas of dense human activity. We examined the relationships between butterfly species richness and human population density at five spatial resolutions ranging from 2' to 60' across South Africa. We used atlas-type data and spatial interpolation techniques aimed at reducing the effect of unequal spatial sampling. Our results confirm the general positive correlation between total species richness and human population density. Contrary to our expectations, the strength of this positive correlation did not weaken at finer spatial resolutions. The patterns observed using total species richness were driven mostly by common species. The richness of threatened and restricted range species was not correlated to human population density. None of the correlations we examined were particularly strong, with much unexplained variance remaining, suggesting that the overlap between butterflies and humans is not strong compared to other factors not accounted for in our analyses. Special consideration needs to be made regarding conservation goals and variables used when investigating the overlap between species and humans for biodiversity conservation. PMID:25915899

Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa.

PubMed

Mecenero, Silvia; Altwegg, Res; Colville, Jonathan F; Beale, Colin M

2015-01-01

Wildlife and humans tend to prefer the same productive environments, yet high human densities often lead to reduced biodiversity. Species richness is often positively correlated with human population density at broad scales, but this correlation could also be caused by unequal sampling effort leading to higher species tallies in areas of dense human activity. We examined the relationships between butterfly species richness and human population density at five spatial resolutions ranging from 2' to 60' across South Africa. We used atlas-type data and spatial interpolation techniques aimed at reducing the effect of unequal spatial sampling. Our results confirm the general positive correlation between total species richness and human population density. Contrary to our expectations, the strength of this positive correlation did not weaken at finer spatial resolutions. The patterns observed using total species richness were driven mostly by common species. The richness of threatened and restricted range species was not correlated to human population density. None of the correlations we examined were particularly strong, with much unexplained variance remaining, suggesting that the overlap between butterflies and humans is not strong compared to other factors not accounted for in our analyses. Special consideration needs to be made regarding conservation goals and variables used when investigating the overlap between species and humans for biodiversity conservation.

Densities of Barrow's goldeneyes during winter in Prince William Sound, Alaska in relation to habitat, food, and history of oil contamination

USGS Publications Warehouse

Esler, Daniel N.; Bowman, Timothy D.; O'Clair, Charles E.; Dean, Thomas A.; McDonald, Lyman L.

2000-01-01

We evaluated variation in densities of Barrow's Goldeneyes (Bucephala islandica) during winter at 214 sites within oiled and unoiled study areas in Prince William Sound, Alaska in relation to physical habitat attributes, prey biomass, and history of habitat contamination by the 1989 Exxon Valdez oil spill. Using general linear model analyses, we found that goldeneye densities were positively associated with occurrence of a stream within 200 m, lack of exposure to wind and waves, and mixed (versus rocky) substrate. We speculate that these associations relate to habitat profitability via selection of beneficial attributes and avoidance of detrimental features. We also determined that biomass of blue mussels (Mytilus trossulus), the primary prey, was not related to Barrow's Goldeneye densities; we suggest that mussel standing stock exceeds predation demands in our study areas and, thus, does not dictate goldeneye distribution. After accounting for habitat effects, we detected no effect of history of oil contamination on Barrow's Goldeneye densities, suggesting that populations have recovered from the oil spill. Although other studies documented hydrocarbon exposure in Barrow's Goldeneyes through at least 1997, either the level of exposure did not affect populations via reductions in survival, or effects of oil exposure were offset by immigration.

Population changes in residential clusters in Japan.

PubMed

Sekiguchi, Takuya; Tamura, Kohei; Masuda, Naoki

2018-01-01

Population dynamics in urban and rural areas are different. Understanding factors that contribute to local population changes has various socioeconomic and political implications. In the present study, we use population census data in Japan to examine contributors to the population growth of residential clusters between years 2005 and 2010. The data set covers the entirety of Japan and has a high spatial resolution of 500 × 500 m2, enabling us to examine population dynamics in various parts of the country (urban and rural) using statistical analysis. We found that, in addition to the area, population density, and age, the shape of the cluster and the spatial distribution of inhabitants within the cluster are significantly related to the population growth rate of a residential cluster. Specifically, the population tends to grow if the cluster is "round" shaped (given the area) and the population is concentrated near the center rather than periphery of the cluster. Combination of the present results and analysis framework with other factors that have been omitted in the present study, such as migration, terrain, and transportation infrastructure, will be fruitful.

Beyond bouncing back : a roundtable on critical transportation resilience

DOT National Transportation Integrated Search

2013-06-01

Global transportation infrastructure today is confronted with significant vulnerabilities an aging : infrastructure; a growing concentration of populations at high-density coastal urban areas; increasing : interdependencies among the nation's phy...

Density of Emerald Ash Borer (Coleoptera: Buprestidae) Adults and Larvae at Three Stages of the Invasion Wave.

PubMed

Burr, Stephen J; McCullough, Deborah G; Poland, Therese M

2018-02-08

Emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), an invasive phloem-feeding buprestid, has killed hundreds of millions of ash (Fraxinus spp.) trees in the United States and two Canadian provinces. We evaluated EAB persistence in post-invasion sites and compared EAB adult captures and larval densities in 24 forested sites across an east-west gradient in southern Michigan representing the Core (post-invasion), Crest (high EAB populations), and Cusp (recently infested areas) of the EAB invasion wave. Condition of green ash (Fraxinus pennsylvanica Marsh) trees were recorded in fixed radius plots and linear transects in each site. Ash mortality was highest in Core sites in the southeast, moderate in Crest sites in central southern Michigan, and low in Cusp sites in the southwest. Traps and trap trees in Crest sites accounted for 75 and 60% of all EAB beetles captured in 2010 and 2011, respectively. Populations of EAB were present in all Core sites and traps in these sites captured 13% of all beetles each year. Beetle captures and larval densities at Cusp sites roughly doubled between 2010 and 2011, reflecting the increasing EAB populations. Sticky bands on girdled trees captured the highest density of EAB beetles per m2 of area, while baited double-decker traps had the highest detection rates and captured the most beetles. Larval densities were higher on girdled ash than on similar ungirdled trees and small planted trees. Woodpecker predation and a native larval parasitoid were present in all three invasion regions but had minor effects on ash survival and EAB densities. © The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Density, Demography, and Influential Environmental Factors on Overwintering Populations of Sogatella furcifera (Hemiptera: Delphacidae) in Southern Yunnan, China.

PubMed

Hu, Shao-Ji; Fu, Da-Ying; Han, Zhong-Liang; Ye, Hui

2015-01-01

Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) is the most serious pest on rice in southwestern China. Yunnan province is within this region and is a major overwintering area for S. furcifera in China. This field study was carried out over 4 yr (2010-2013) and focused on S. furcifera distribution, population density, and demography, as well as the relationship between various environmental factors and the distribution and density of overwintering S. furcifera in Yunnan. Our study demonstrated that overwintering populations of S. furcifera mainly occurred in valleys and lowlands below 25.02°N and 1,608 m above sea level (a.s.l.), where ratooning rice was present [corrected]. The overwintering range of S. furcifera has expanded in Yunnan compared with 20 yr ago, and regional climate change is believed to be the main contributing cause for this expansion. Environmental factor analysis showed that the mean air temperature of the coldest quarter and precipitation of the coldest quarter were two key factors that were strongly linked to the overwintering distribution and density of S. furcifera in Yunnan. Wintertime temperature was the principal influencing factor to determine the distribution and density of S. furcifera, while the effect of precipitation was indirect in that it influenced the insect's distribution via its host. This study documented the major overwintering areas of S. furcifera in Yunnan, which can be used to predict outbreak potential in the following spring. Hence, key climatic factors, overwintering distribution, and density of S. furcifera should be used when forecasting outbreaks in spring. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Using a geolocation social networking application to calculate the population density of sex-seeking gay men for research and prevention services.

PubMed

Delaney, Kevin P; Kramer, Michael R; Waller, Lance A; Flanders, W Dana; Sullivan, Patrick S

2014-11-18

In the United States, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) continues to have a heavy impact on men who have sex with men (MSM). Among MSM, black men under the age of 30 are at the most risk for being diagnosed with HIV. The US National HIV/AIDS strategy recommends intensifying efforts in communities that are most heavily impacted; to do so requires new methods for identifying and targeting prevention resources to young MSM, especially young MSM of color. We piloted a methodology for using the geolocation features of social and sexual networking applications as a novel approach to calculating the local population density of sex-seeking MSM and to use self-reported age and race from profile postings to highlight areas with a high density of minority and young minority MSM in Atlanta, Georgia. We collected data from a geographically systematic sample of points in Atlanta. We used a sexual network mobile phone app and collected application profile data, including age, race, and distance from each point, for either the 50 closest users or for all users within a 2-mile radius of sampled points. From these data, we developed estimates of the spatial density of application users in the entire city, stratified by race. We then compared the ratios and differences between the spatial densities of black and white users and developed an indicator of areas with the highest density of users of each race. We collected data from 2666 profiles at 79 sampled points covering 883 square miles; overlapping circles of data included the entire 132.4 square miles in Atlanta. Of the 2666 men whose profiles were observed, 1563 (58.63%) were white, 810 (30.38%) were black, 146 (5.48%) were another race, and 147 (5.51%) did not report a race in their profile. The mean age was 31.5 years, with 591 (22.17%) between the ages of 18-25, and 496 (18.60%) between the ages of 26-30. The mean spatial density of observed profiles was 33 per square mile, but the distribution of profiles observed across the 79 sampled points was highly skewed (median 17, range 1-208). Ratio, difference, and distribution outlier measures all provided similar information, highlighting areas with higher densities of minority and young minority MSM. Using a limited number of sampled points, we developed a geospatial density map of MSM using a social-networking sex-seeking app. This approach provides a simple method to describe the density of specific MSM subpopulations (users of a particular app) for future HIV behavioral surveillance and allow targeting of prevention resources such as HIV testing to populations and areas of highest need.

Territorial behavior, pesticides, and the population ecology of red-shouldered hawks in central Maryland, 1943-1971

USGS Publications Warehouse

Henny, C.J.; Schmid, F.C.; Martin, E.M.; Hood, L.L.

1973-01-01

A breeding population of red-shouldered hawks (Buteo lineatus) along the Patuxent River in central Maryland was studied during the interval 1943-71. Numbers of breeding pairs remained unchanged or increased on the PWRC (Patuxent Wildlife Research Center) and an adjoining area where habitat was not altered. A reduction in breeding pairs occurred on the third study area where large portions of the habitat had been destroyed. Basic information on 74 nests was obtained and the annual number of breeding pairs on the PWRC ranged from a low of four to a high of nine during the study. Nesting success of this highly territorial species decreased significantly as the distance between adjacent nest sites decreased (Errington's principle of inversity). Since 1960, the recruitment rate during high density years was 1.34 young fledged per pair as opposed to 1.95 during optimum (1943 and 1947 levels) density years. The 1.95 figure compared favorably with the estimated recruitment rate necessary for maintaining a stable population and with recruitment rates observed in other locations prior to the modern pesticide era. As the observed recruitment rate during the 4 years of optimum density was believed adequate, it is doubtful that the relatively low pesticide levels in the eggs had a detrimental effect on the reproductive performance of the population.

Sprawl in European urban areas

NASA Astrophysics Data System (ADS)

Prastacos, Poulicos; Lagarias, Apostolos

2016-08-01

In this paper the 2006 edition of the Urban Atlas database is used to tabulate areas of low development density, usually referred to as "sprawl", for many European cities. The Urban Atlas database contains information on the land use distribution in the 305 largest European cities. Twenty different land use types are recognized, with six of them representing urban fabric. Urban fabric classes are residential areas differentiated by the density of development, which is measured by the sealing degree parameter that ranges from 0% to 100% (non-developed, fully developed). Analysis is performed on the distribution of the middle to low density areas defined as those with sealing degree less than 50%. Seven different country groups in which urban areas have similar sprawl characteristics are identified and some key characteristics of sprawl are discussed. Population of an urban area is another parameter considered in the analysis. Two spatial metrics, average patch size and mean distance to the nearest neighboring patch of the same class, are used to describe proximity/separation characteristics of sprawl in the urban areas of the seven groups.

Importance of the National Petroleum Reserve-Alaska for aquatic birds

USGS Publications Warehouse

Bart, Jonathan; Platte, Robert M.; Andres, Brad; Brown, Stephen; Johnson, James A.; Larned, William

2013-01-01

We used data from aerial surveys (1992–2010) of >100,000 km2 and ground surveys (1998–2004) of >150 km2 to estimate the density and abundance of birds on the North Slope of Alaska (U.S.A.). In the ground surveys, we used double sampling to estimate detection ratios. We used the aerial survey data to compare densities of birds and Arctic fox (Vulpes lagopus), the major nest predator of birds, on the North Slope, in Prudhoe Bay, and in nearby areas. We partitioned the Prudhoe Bay oil field into 2 × 2 km plots and determined the relation between density of aquatic birds and density of roads, buildings, and other infrastructure in these plots. Abundance and density (birds per square kilometer) of 3 groups of aquatic birds—waterfowl, loons, and grebes; shorebirds; and gulls, terns, and jaegers—were highest in the National Petroleum Reserve–Alaska (NPRA) and lowest in the Arctic National Wildlife Refuge. Six other major wetlands occur in the Arctic regions of Canada and Russia, but the largest population of aquatic birds was in the NPRA. Aquatic birds were concentrated in the northern part of the NPRA. For example, an area that covered 18% of the NPRA included 53% of its aquatic birds. The aerial surveys showed that bird density was not lower and fox density was not higher in Prudhoe Bay than in surrounding areas. Density of infrastructure did not significantly affect bird density for any group of species. Our results establish that the NPRA is one of the most important areas for aquatic birds in the Arctic. Our results and those of others also indicate that oil production, as practiced in Prudhoe Bay, does not necessarily lead to substantial declines in bird density or productivity in or near the developed areas.

Spatial relationships between tropical cyclone frequencies and population densities in Haiti since the 19th century

NASA Astrophysics Data System (ADS)

Klose, C. D.

2011-12-01

The second edition of the United Nations Global Assessment Report on Disaster Risk Reduction in 2011 outlined that the worldwide physical exposure to tropical cyclones increased by 192 per cent between 1970 and 2010. For the past 160 years, the Republic of Haiti has experienced numerous tropical storms and hurricanes which may have directly effected the country's development path. However, statistical data regarding storm frequencies and population densities in space and time show that the population's exposure in Haiti may have more negatively influenced its development than the actual number of storms and hurricanes. Haitians, in particular, those living in urban areas have been exposed to much higher tropical cyclone hazards than rural areas since the second half of the 20th century. Specifically, more storms made landfall in regions of accelerated migration/urbanization, such as, in departments Ouest, Artibonite, Nord, and Nord-Ouest with Haiti's four largest cities Port-au-Prince, Gonaives, Cap-Haitien and Port-de-Paix.

Prevalence of Salmonella strains in wild animals from a highly populated area of north-eastern Italy.

PubMed

Rubini, Silva; Ravaioli, Cinzia; Previato, Sara; D'Incau, Mario; Tassinari, Massimo; Guidi, Enrica; Lupi, Silvia; Merialdi, Giuseppe; Bergamini, Mauro

2016-01-01

Salmonella is a ubiquitous pathogen that can infect host species, like wild birds, rodents, and/or arthropods, which may transmit infection to domestic animals and human population. In order to assess the related risk, a cross-sectional study was performed on 1114 carcasses of wild animals from a north-eastern area of the Emilia-Romagna Region, Italy. During post mortem examination, intestine samples were cultured. A statistical analysis demonstrated that there is no correlation between the presence of sub-clinically infected animals and greater human population density. In contrast, a significant correlation between the number of carcasses positive for Salmonella spp. and greater spatial density of pig, poultry, and cattle farms was observed (p < 0.01). The results of the present study show that wild animals with omnivorous feeding habits are particularly exposed to Salmonella colonization and, consequently, to spreading the organism. Regarding drug resistance, this study confirms the resistance to antimicrobials is increasing in commensal and environmental isolates.

Spatial and temporal variation in proportional stock density and relative weight of smallmouth bass in a reservoir

USGS Publications Warehouse

Mesa, Matthew G.; Duke, S.D.; Ward, David L.

1990-01-01

Population data for smallmouth bass Micropterus dolomieui in 20,235 ha John Day Reservoir on the Columbia River were used to (1) determine whether Proportional Stock Density (PSD) and Relative Weight (Wr) varied spatially and temporally in two areas of the reservoir with established smallmouth bass fisheries; (2) explore possible causes of any observed variation; and (3) discuss some management implications and recommendations. Both PSD and Wr varied spatially and monthly in all years examined. On an annual basis, PSD varied at one area but not at the other, whereas Wr showed little variation. Possible explanations for the variation in PSD and Wr are differences in growth, mortality, recruitment, and exploitation. Our data suggested that regulations established or changed on a reservoir-wide basis may have different effects on the fishery, depending on location in the reservoir. Also, pooling data from various areas within a reservoir to yield point estimates of structural indices may not represent the variation present in the population as a whole. The significant temporal variability reflects the importance of determining the proper time to sample fish to yield representative estimates of the variable of interest. In areas with valuable fisheries or markedly different population structures, we suggest that an area-specific approach be made to reservoir fishery management, and that efforts be made toward effecting consistent harvest regulations in interstate waters.

Avian use of Sheyenne Lake and associated habitats in central North Dakota

USGS Publications Warehouse

Faanes, Craig A.

1982-01-01

A study of avian use of various habitats was conducted in the Sheyenne Lake region of central North Dakota during April-June 1980. Population counts of birds were made in wetlands of various classes, prairie thickets, upland native prairie, shelterbelts, and cropland. About 22,000 breeding bird pairs including 92 species that nested occupied the area. Population means for most species were equal to or greater than statewide means. Red-winged blackbird (Agelaius phoeniceus), yellow-headed blackbird (Xanthocephalus xanthocephalus), mourning dove (Zenaida macroura), and blue-winged teal (Anas discors) were the most numerous species, and made up 32.9% of the total population . Highest densities of breeding birds occurred in shelterbelts, semipermanent wetlands, and prairie thickets. Lowest densities occurred in upland native prairie and cropland. The study area was used by 49.6% of the total avifauna of the State, and 51% of the breeding avifauna of North Dakota probably nested in the study area. The diversity of birds using the area was unusual in that such a large number of species occupied a relatively small area. The close interspersion of many native habitats, several of which are unique in North Dakota, probably accounted for this diversity. Data on dates of occurrence, nesting records, and habitat use are presented for the 175 species recorded in 1980. Observations of significance by refuge staff are also provided.

Spatially Explicit Modeling Reveals Cephalopod Distributions Match Contrasting Trophic Pathways in the Western Mediterranean Sea

PubMed Central

Puerta, Patricia; Hunsicker, Mary E.; Quetglas, Antoni; Álvarez-Berastegui, Diego; Esteban, Antonio; González, María; Hidalgo, Manuel

2015-01-01

Populations of the same species can experience different responses to the environment throughout their distributional range as a result of spatial and temporal heterogeneity in habitat conditions. This highlights the importance of understanding the processes governing species distribution at local scales. However, research on species distribution often averages environmental covariates across large geographic areas, missing variability in population-environment interactions within geographically distinct regions. We used spatially explicit models to identify interactions between species and environmental, including chlorophyll a (Chla) and sea surface temperature (SST), and trophic (prey density) conditions, along with processes governing the distribution of two cephalopods with contrasting life-histories (octopus and squid) across the western Mediterranean Sea. This approach is relevant for cephalopods, since their population dynamics are especially sensitive to variations in habitat conditions and rarely stable in abundance and location. The regional distributions of the two cephalopod species matched two different trophic pathways present in the western Mediterranean Sea, associated with the Gulf of Lion upwelling and the Ebro river discharges respectively. The effects of the studied environmental and trophic conditions were spatially variant in both species, with usually stronger effects along their distributional boundaries. We identify areas where prey availability limited the abundance of cephalopod populations as well as contrasting effects of temperature in the warmest regions. Despite distributional patterns matching productive areas, a general negative effect of Chla on cephalopod densities suggests that competition pressure is common in the study area. Additionally, results highlight the importance of trophic interactions, beyond other common environmental factors, in shaping the distribution of cephalopod populations. Our study presents a valuable approach for understanding the spatially variant ecology of cephalopod populations, which is important for fisheries and ecosystem management. PMID:26201075

Dentist shortage: an analysis of dentists, practices, and populations in the underserved areas.

PubMed

Voinea-Griffin, Andreea; Solomon, Eric S

2016-09-01

The objectives of this study are to identify and describe the characteristics of dental underserved geographic areas. Understanding these characteristics is an important step in addressing access to dental care barriers. Dental underserved areas were identified from the Health Resources and Services Administration (HRSA) database and converted to census tracts for analysis. Characteristics of dental underserved geographic areas were compared with areas not designated as underserved. Dental practices included in the Dun & Bradstreet Business information database were geocoded and analyzed according to the underserved designation of their location and census demographic data. Thus, the relationships between dental underserved status, practice, and population characteristics were evaluated. Dental underserved areas are more likely to comprise individuals with lower socio-economic status (income and education levels), higher levels of underrepresented population groups, and have lower population densities than non-underserved areas. The populations living in dental underserved areas are more likely to experience geographic, financial, and educational barriers to dental care. The study identifies the geographic and financial barriers to dental care access. These findings suggest that the likelihood of a market-driven solution to dental underserved geographic areas is low and support public sector interventions to improve the status quo. © 2016 American Association of Public Health Dentistry.

Raptor community composition in the Texas Southern High Plains lesser prairie-chicken range

USGS Publications Warehouse

Behney, A.C.; Boal, Clint W.; Whitlaw, Heather A.; Lucia, D.R.

2012-01-01

Predation can be a factor in preventing prey population growth and sustainability when prey populations are small and fragmented, and when predator density is unrelated to the density of the single prey species. We conducted monthly raptor surveys from February 2007 to May 2009 in adjacent areas of the Texas Southern High Plains (USA) that do and do not support lesser prairie-chickens (Tympanuchus pallidicinctus), a candidate for protection under the Endangered Species Act. During the summer period corresponding to prairie-chicken nesting and brood-rearing, Swainson's hawks (Buteo swainsoni) were the most abundant raptor. During the lekking and overwintering period, the raptor community was diverse, with northern harriers (Circus cyaneus) being the most abundant species. Raptor abundance peaked during the early autumn and was lowest during the spring. Utility poles were a significant predictor of raptor density at survey points and Swainson's hawks and all raptors, pooled, were found in greater densities in non-prairie-chicken habitat dominated by mesquite (Prosopis glandulosa). Avian predation risk on prairie-chickens, based on presence and abundance of raptors, appears to be greatest during winter when there is a more abundant and diverse raptor community, and in areas with utility poles.

Density dependence, whitebark pine, and vital rates of grizzly bears

USGS Publications Warehouse

van Manen, Frank T.; Haroldson, Mark A.; Bjornlie, Daniel D.; Ebinger, Michael R.; Thompson, Daniel J.; Costello, Cecily M.; White, Gary C.

2016-01-01

Understanding factors influencing changes in population trajectory is important for effective wildlife management, particularly for populations of conservation concern. Annual population growth of the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem, USA has slowed from 4.2–7.6% during 1983–2001 to 0.3–2.2% during 2002–2011. Substantial changes in availability of a key food source and bear population density have occurred. Whitebark pine (Pinus albicaulis), the seeds of which are a valuable but variable fall food for grizzly bears, has experienced substantial mortality primarily due to a mountain pine beetle (Dendroctonus ponderosae) outbreak that started in the early 2000s. Positive growth rates of grizzly bears have resulted in populations reaching high densities in some areas and have contributed to continued range expansion. We tested research hypotheses to examine if changes in vital rates detected during the past decade were more associated with whitebark pine decline or, alternatively, increasing grizzly bear density. We focused our assessment on known-fate data to estimate survival of cubs-of-the-year (cubs), yearlings, and independent bears (≥2 yrs), and reproductive transition of females from having no offspring to having cubs. We used spatially and temporally explicit indices for grizzly bear density and whitebark pine mortality as individual covariates. Models indicated moderate support for an increase in survival of independent male bears over 1983–2012, whereas independent female survival did not change. Cub survival, yearling survival, and reproductive transition from no offspring to cubs all changed during the 30-year study period, with lower rates evident during the last 10–15 years. Cub survival and reproductive transition were negatively associated with an index of grizzly bear density, indicating greater declines where bear densities were higher. Our analyses did not support a similar relationship for the index of whitebark pine mortality. The results of our study support the interpretation that slowing of population growth during the last decade was associated more with increasing grizzly bear density than the decline in whitebark pine. Grizzly bear density and its potential effect on vital rates and population trajectory warrant consideration for management of the grizzly bear population in the Greater Yellowstone Ecosystem.

Mixed-Forest Species Establishment in a Monodominant Forest in Central Africa: Implications for Tropical Forest Invasibility

PubMed Central

Peh, Kelvin S.-H.; Sonké, Bonaventure; Séné, Olivier; Djuikouo, Marie-Noël K.; Nguembou, Charlemagne K.; Taedoumg, Hermann; Begne, Serge K.; Lewis, Simon L.

2014-01-01

Background Traits of non-dominant mixed-forest tree species and their synergies for successful co-occurrence in monodominant Gilbertiodendron dewevrei forest have not yet been investigated. Here we compared the tree species diversity of the monodominant forest with its adjacent mixed forest and then determined which fitness proxies and life history traits of the mixed-forest tree species were most associated with successful co-existence in the monodominant forest. Methodology/Principal Findings We sampled all trees (diameter in breast height [dbh]≥10 cm) within 6×1 ha topographically homogenous areas of intact central African forest in SE Cameroon, three independent patches of G. dewevrei-dominated forest and three adjacent areas (450–800 m apart). Monodominant G. dewevrei forest had lower sample-controlled species richness, species density and population density than its adjacent mixed forest in terms of stems with dbh≥10 cm. Analysis of a suite of population-level characteristics, such as relative abundance and geographical distribution, and traits such as wood density, height, diameter at breast height, fruit/seed dispersal mechanism and light requirement–revealed after controlling for phylogeny, species that co-occur with G. dewevrei tend to have higher abundance in adjacent mixed forest, higher wood density and a lower light requirement. Conclusions/Significance Our results suggest that certain traits (wood density and light requirement) and population-level characteristics (relative abundance) may increase the invasibility of a tree species into a tropical closed-canopy system. Such knowledge may assist in the pre-emptive identification of invasive tree species. PMID:24844914

Relative effects of climatic and local factors on fire occurrence in boreal forest landscapes of northeastern China.

PubMed

Wu, Zhiwei; He, Hong S; Yang, Jian; Liu, Zhihua; Liang, Yu

2014-09-15

Fire significantly affects species composition, structure, and ecosystem processes in boreal forests. Our study objective was to identify the relative effects of climate, vegetation, topography, and human activity on fire occurrence in Chinese boreal forest landscapes. We used historical fire ignition for 1966-2005 and the statistical method of Kernel Density Estimation to derive fire-occurrence density (number of fires/km(2)). The Random Forest models were used to quantify the relative effects of climate, vegetation, topography, and human activity on fire-occurrence density. Our results showed that fire-occurrence density tended to be spatially clustered. Human-caused fire occurrence was highly clustered at the southern part of the region, where human population density is high (comprising about 75% of the area's population). In the north-central areas where elevations are the highest in the region and less densely populated, lightning-caused fires were clustered. Climate factors (e.g., fine fuel and duff moisture content) were important at both regional and landscape scales. Human activity factors (e.g., distance to nearest settlement and road) were secondary to climate as the primary fire occurrence factors. Predictions of fire regimes often assume a strong linkage between climate and fire but usually with less emphasis placed on the effects of local factors such as human activity. We therefore suggest that accurate forecasting of fire regime should include human influences such as those measured by forest proximity to roads and human settlements. Copyright © 2014 Elsevier B.V. All rights reserved.

Population distribution, density and habitat preference of the Cerulean Warbler (Setophaga cerulea) in the Delaware Water Gap National Recreation Area

Treesearch

Shannon Curley; Terry Master; Gregory George

2012-01-01

The breeding range of the Cerulean Warbler has expanded into second-growth forest and converted agricultural land in the northeastern United States where, according to the North American Breeding Bird Survey, the population is increasing. Despite this expansion in one part of its range, the population as a whole is still in rapid decline implying that habitat quality...

The role of phenotype structure in the population dynamics of gypsy moth in the Lower Dnieper region

Treesearch

Nikolaj M. Derevyanko

1991-01-01

One of the characteristic features of the gypsy moth population in the Lower Dnieper area is its variable larval coloring. Phenotype frequency has been recorded over the years in separate micropopulations at different density levels. The data show the population to consist mainly of gray larvae in all life stages, and their abundance varying from 85 to 99.6 percent....

Effects of social organization, trap arrangement and density, sampling scale, and population density on bias in population size estimation using some common mark-recapture estimators.

PubMed

Gupta, Manan; Joshi, Amitabh; Vidya, T N C

2017-01-01

Mark-recapture estimators are commonly used for population size estimation, and typically yield unbiased estimates for most solitary species with low to moderate home range sizes. However, these methods assume independence of captures among individuals, an assumption that is clearly violated in social species that show fission-fusion dynamics, such as the Asian elephant. In the specific case of Asian elephants, doubts have been raised about the accuracy of population size estimates. More importantly, the potential problem for the use of mark-recapture methods posed by social organization in general has not been systematically addressed. We developed an individual-based simulation framework to systematically examine the potential effects of type of social organization, as well as other factors such as trap density and arrangement, spatial scale of sampling, and population density, on bias in population sizes estimated by POPAN, Robust Design, and Robust Design with detection heterogeneity. In the present study, we ran simulations with biological, demographic and ecological parameters relevant to Asian elephant populations, but the simulation framework is easily extended to address questions relevant to other social species. We collected capture history data from the simulations, and used those data to test for bias in population size estimation. Social organization significantly affected bias in most analyses, but the effect sizes were variable, depending on other factors. Social organization tended to introduce large bias when trap arrangement was uniform and sampling effort was low. POPAN clearly outperformed the two Robust Design models we tested, yielding close to zero bias if traps were arranged at random in the study area, and when population density and trap density were not too low. Social organization did not have a major effect on bias for these parameter combinations at which POPAN gave more or less unbiased population size estimates. Therefore, the effect of social organization on bias in population estimation could be removed by using POPAN with specific parameter combinations, to obtain population size estimates in a social species.

Effects of social organization, trap arrangement and density, sampling scale, and population density on bias in population size estimation using some common mark-recapture estimators

PubMed Central

Joshi, Amitabh; Vidya, T. N. C.

2017-01-01

Mark-recapture estimators are commonly used for population size estimation, and typically yield unbiased estimates for most solitary species with low to moderate home range sizes. However, these methods assume independence of captures among individuals, an assumption that is clearly violated in social species that show fission-fusion dynamics, such as the Asian elephant. In the specific case of Asian elephants, doubts have been raised about the accuracy of population size estimates. More importantly, the potential problem for the use of mark-recapture methods posed by social organization in general has not been systematically addressed. We developed an individual-based simulation framework to systematically examine the potential effects of type of social organization, as well as other factors such as trap density and arrangement, spatial scale of sampling, and population density, on bias in population sizes estimated by POPAN, Robust Design, and Robust Design with detection heterogeneity. In the present study, we ran simulations with biological, demographic and ecological parameters relevant to Asian elephant populations, but the simulation framework is easily extended to address questions relevant to other social species. We collected capture history data from the simulations, and used those data to test for bias in population size estimation. Social organization significantly affected bias in most analyses, but the effect sizes were variable, depending on other factors. Social organization tended to introduce large bias when trap arrangement was uniform and sampling effort was low. POPAN clearly outperformed the two Robust Design models we tested, yielding close to zero bias if traps were arranged at random in the study area, and when population density and trap density were not too low. Social organization did not have a major effect on bias for these parameter combinations at which POPAN gave more or less unbiased population size estimates. Therefore, the effect of social organization on bias in population estimation could be removed by using POPAN with specific parameter combinations, to obtain population size estimates in a social species. PMID:28306735

Increasing Youths' Exposure to a Tobacco Prevention Media Campaign in Rural and Low-Population-Density Communities

PubMed Central

Vallone, Donna M.; Allen, Jane A.; Cullen, Jennifer; Mowery, Paul D.; Xiao, Haijun; Dorrler, Nicole; Asche, Eric T.; Healton, Cheryl

2009-01-01

Objectives. We examined the effectiveness of a program to increase exposure to national “truth” tobacco countermarketing messages among youths in rural and low-population-density communities. Methods. A longitudinal survey of 2618 youths aged 12 to 17 years was conducted over 5 months in 8 media markets receiving supplemental advertising and 8 comparison markets receiving less than the national average of “truth” messages. Results. Confirmed awareness of “truth” increased from 40% to 71% among youths in treatment markets while remaining stable in comparison markets. Over 35% of all youths who were unaware of the campaign at baseline became aware of it as a direct result of the increased advertising. Youths living in rural and low-population-density communities were receptive to the campaign's messages. Conclusions. Through purchase of airtime in local broadcast media, the reach of a national tobacco countermarketing campaign was expanded among youths living in rural and low-population-density areas. This strategy of augmenting delivery of nationally broadcast antitobacco ads can serve as a model for leveraging limited tobacco control resources to increase the impact of evidence-based tobacco prevention campaigns. PMID:19833994

Exploring spatial patterns and drivers of forest fires in Portugal (1980-2014).

PubMed

Nunes, A N; Lourenço, L; Meira, A C Castro

2016-12-15

Information on the spatial incidence of fire ignition density and burnt area, trends and drivers of wildfires is vitally important in providing support for environmental and civil protection policies, designing appropriate prevention measures and allocating firefighting resources. The key objectives of this study were to analyse the geographical incidence and temporal trends for wildfires, as well as the main drivers of fire ignition and burnt area in Portugal on a municipal level. The results show that fires are not distributed uniformly throughout Portuguese territory, both in terms of ignition density and burnt area. One spot in the north-western area is well defined, covering 10% of the municipalities where more than one third of the total fire ignitions are concentrated. In >80% of Portuguese municipalities, ignition density has registered a positive trend since the 1980s. With regard to burnt area, 60% of the municipalities had a nil annual trend, 35% showed a positive trend and 5%, located mainly in the central region, revealed negative trends. Geographically weighted regression proved more efficient in identifying the most relevant physical and anthropogenic drivers of municipal wildfires in comparison with simple linear regression models. Topography, density of population, land cover and livestock were found to be significant in both ignition density and burnt area, although considerable variations were observed in municipal explanatory power. Copyright © 2016 Elsevier B.V. All rights reserved.

Herd-level bovine tuberculosis risk factors: assessing the role of low-level badger population disturbance.

PubMed

Wright, David M; Reid, Neil; Ian Montgomery, W; Allen, Adrian R; Skuce, Robin A; Kao, Rowland R

2015-08-17

Bovine TB (bTB) is endemic in Irish cattle and has eluded eradication despite considerable expenditure, amid debate over the relative roles of badgers and cattle in disease transmission. Using a comprehensive dataset from Northern Ireland (>10,000 km(2); 29,513 cattle herds), we investigated interactions between host populations in one of the first large-scale risk factor analyses for new herd breakdowns to combine data on both species. Cattle risk factors (movements, international imports, bTB history, neighbours with bTB) were more strongly associated with herd risk than area-level measures of badger social group density, habitat suitability or persecution (sett disturbance). Highest risks were in areas of high badger social group density and high rates of persecution, potentially representing both responsive persecution of badgers in high cattle risk areas and effects of persecution on cattle bTB risk through badger social group disruption. Average badger persecution was associated with reduced cattle bTB risk (compared with high persecution areas), so persecution may contribute towards sustaining bTB hotspots; findings with important implications for existing and planned disease control programmes.

The role of density dependence in growth patterns of ceded territory walleye populations of northern Wisconsin: Effects of changing management regimes

USGS Publications Warehouse

Sass, G.G.; Hewett, S.W.; Beard, T.D.; Fayram, A.H.; Kitchell, J.F.

2004-01-01

We assessed density-related changes in growth of walleye Sander vitreus in the ceded territory of northern Wisconsin from 1977 to 1999. We used asymptotic length (Lz), growth rate near t0 (??), and body condition as measures of walleye growth to determine the relationship between growth and density. Among lakes, there was weak evidence of density-dependent growth: adult density explained only 0-6% of the variability in the growth metrics. Within lakes, growth was density dependent. Lz, ??, and body condition of walleyes changing with density for 69, 28, and 62% of the populations examined, respectively. Our results suggest that walleye growth was density dependent within individual lakes. However, growth was not coherently density dependent among lakes, which was possibly due to inherent differences in the productivity, surface area, forage base, landscape position, species composition, and management regime of lakes in the ceded territory. Densities of adult walleyes averaged 8.3 fish/ha and did not change significantly during 1990-1999. Mean Lz and body condition of walleyes were signilicantly higher before 1990 than after 1990, which may indicate an increase in density due to changes in management regimes. The observed growth changes do not appear to be a consequence of the statewide 15-in minimum size limit adopted in 1990 but rather a response to the treaty rights management regime. We conclude that walleye growth has the potential to predict regional-scale adult walleye densities if lake-specific variables are included in a model to account for regional-scale differences among walleye populations and lakes.

A log-linear model approach to estimation of population size using the line-transect sampling method

USGS Publications Warehouse

Anderson, D.R.; Burnham, K.P.; Crain, B.R.

1978-01-01

The technique of estimating wildlife population size and density using the belt or line-transect sampling method has been used in many past projects, such as the estimation of density of waterfowl nestling sites in marshes, and is being used currently in such areas as the assessment of Pacific porpoise stocks in regions of tuna fishing activity. A mathematical framework for line-transect methodology has only emerged in the last 5 yr. In the present article, we extend this mathematical framework to a line-transect estimator based upon a log-linear model approach.

10 CFR 960.5-2-3 - Meteorology.

Code of Federal Regulations, 2013 CFR

2013-01-01

... operation and closure will not be likely to lead to radionuclide releases to an unrestricted area greater... with higher population densities than are the average for the region. (2) History of extreme weather...

10 CFR 960.5-2-3 - Meteorology.

Code of Federal Regulations, 2014 CFR

2014-01-01

... operation and closure will not be likely to lead to radionuclide releases to an unrestricted area greater... with higher population densities than are the average for the region. (2) History of extreme weather...

10 CFR 960.5-2-3 - Meteorology.

Code of Federal Regulations, 2012 CFR

2012-01-01

... operation and closure will not be likely to lead to radionuclide releases to an unrestricted area greater... with higher population densities than are the average for the region. (2) History of extreme weather...

Comparison of large crater and multiringed basin populations on Mars, Mercury, and the moon

NASA Technical Reports Server (NTRS)

Malin, M. C.

1976-01-01

The maximum regional areal densities of large impact craters on Mars, Mercury, and the moon appear to be inversely proportional to the surface areas of the planets. This would not be expected if the objects impacting the planetary surfaces came from common sources and were moving with high velocities relative to the planets; rather, a uniform areal density would be anticipated. Another way of stating the observation is that each planet was bombarded by the same number of objects. Two speculative explanations for the observation are that: (1) all planets underwent a uniform bombardment but were resurfaced by processes proportional to planetary surface area, or (2) equally populated families of objects, moving about the sun in orbits similar to those of the planets, were independently depopulated by the respective planets.

Western spruce budworm as related to stand characteristics in the bitterroot national forest

Treesearch

Carroll B. Williams; Patrick J. Shea; Gerald S. Walton

1971-01-01

Relation of population density to certain stand conditions and damage indicators was analyzed in four drainages on the Bitterroot National Forest of Montana. Western spruce budworm (Choristoneura occidentalis Freeman) populations were strongly related to plot basal area, tree species, and tree crown levels, and also to current and past levels of tree defoliation....

42 CFR 414.410 - Phased-in implementation of competitive bidding programs.

Code of Federal Regulations, 2010 CFR

2010-10-01

... variables: (1) The total population of an MSA. (2) The Medicare allowed charges for DMEPOS items per fee-for-service beneficiary in an MSA. (3) The total number of DMEPOS suppliers per fee-for-service beneficiary... area with low population density based on one or more of the following factors— (1) Low utilization of...

Immigration Rates during Population Density Reduction in a Coral Reef Fish

PubMed Central

Turgeon, Katrine; Kramer, Donald L.

2016-01-01

Although the importance of density-dependent dispersal has been recognized in theory, few empirical studies have examined how immigration changes over a wide range of densities. In a replicated experiment using a novel approach allowing within-site comparison, we examined changes in immigration rate following the gradual removal of territorial damselfish from a limited area within a much larger patch of continuous habitat. In all sites, immigration occurred at intermediate densities but did not occur before the start of removals and only rarely as density approached zero. In the combined data and in 5 of 7 sites, the number of immigrants was a hump-shaped function of density. This is the first experimental evidence for hump-shaped, density-dependent immigration. This pattern may be more widespread than previously recognized because studies over more limited density ranges have identified positive density dependence at low densities and negative density dependence at high densities. Positive density dependence at low density can arise from limits to the number of potential immigrants and from behavioral preferences for settling near conspecifics. Negative density dependence at high density can arise from competition for resources, especially high quality territories. The potential for non-linear effects of local density on immigration needs to be recognized for robust predictions of conservation reserve function, harvest impacts, pest control, and the dynamics of fragmented populations. PMID:27271081

Spatial distribution of Munida intermedia and M. sarsi (crustacea: Anomura) on the Galician continental shelf (NW Spain): Application of geostatistical analysis

NASA Astrophysics Data System (ADS)

Freire, J.; González-Gurriarán, E.; Olaso, I.

1992-12-01

Geostatistical methodology was used to analyse spatial structure and distribution of the epibenthic crustaceans Munida intermedia and M. sarsi within sets of data which had been collected during three survey cruises carried out on the Galician continental shelf (1983 and 1984). This study investigates the feasibility of using geostatistics for data collected according to traditional methods and of enhancing such methodology. The experimental variograms were calculated (pooled variance minus spatial covariance between samples taken one pair at a time vs. distance) and fitted to a 'spherical' model. The spatial structure model was used to estimate the abundance and distribution of the populations studied using the technique of kriging. The species display spatial structures, which are well marked during high density periods and in some areas (especially northern shelf). Geostatistical analysis allows identification of the density gradients in space as well as the patch grain along the continental shelf of 16-25 km diameter for M. intermedia and 12-20 km for M. sarsi. Patches of both species have a consistent location throughout the different cruises. As in other geographical areas, M. intermedia and M. sarsi usually appear at depths ranging from 200 to 500 m, with the highest densities in the continental shelf area located between Fisterra and Estaca de Bares. Althouh sampling was not originally designed specifically for geostatistics, this assay provides a measurement of spatial covariance, and shows variograms with variable structure depending on population density and geographical area. These ideas are useful in improving the design of future sampling cruises.

Scrub typhus islands in the Taiwan area and the association between scrub typhus disease and forest land use and farmer population density: geographically weighted regression.

PubMed

Tsai, Pui-Jen; Yeh, Hsi-Chyi

2013-04-29

The Taiwan area comprises the main island of Taiwan and several small islands located off the coast of the Southern China. The eastern two-thirds of Taiwan are characterized by rugged mountains covered with tropical and subtropical vegetation. The western region of Taiwan is characterized by flat or gently rolling plains. Geographically, the Taiwan area is diverse in ecology and environment, although scrub typhus threatens local human populations. In this study, we investigate the effects of seasonal and meteorological factors on the incidence of scrub typhus infection among 10 local climate regions. The correlation between the spatial distribution of scrub typhus and cultivated forests in Taiwan, as well as the relationship between scrub typhus incidence and the population density of farm workers is examined. We applied Pearson's product moment correlation to calculate the correlation between the incidence of scrub typhus and meteorological factors among 10 local climate regions. We used the geographically weighted regression (GWR) method, a type of spatial regression that generates parameters disaggregated by the spatial units of analysis, to detail and map each regression point for the response variables of the standardized incidence ratio (SIR)-district scrub typhus. We also applied the GWR to examine the explanatory variables of types of forest-land use and farm worker density in Taiwan in 2005. In the Taiwan Area, scrub typhus endemic areas are located in the southeastern regions and mountainous townships of Taiwan, as well as the Pescadore, Kinmen, and Matou Islands. Among these islands and low-incidence areas in the central western and southwestern regions of Taiwan, we observed a significant correlation between scrub typhus incidence and surface temperature. No similar significant correlation was found in the endemic areas (e.g., the southeastern region and the mountainous area of Taiwan). Precipitation correlates positively with scrub typhus incidence in 3 local climate regions (i.e., Taiwan's central western and southwestern regions, and the Kinmen Islands). Relative humidity correlates positively with incidence in Southwestern Taiwan and the Kinmen Islands. The number of wet days correlates positively with incidence in Southwestern Taiwan. The duration of sunshine correlates positively with incidence in Central Western Taiwan, as well as the Kinmen and Matou Islands. In addition, the 10 local climatic regions can be classified into the following 3 groups, based on the warm-cold seasonal fluctuations in scrub typhus incidence: (a) Type 1, evident in 5 local climate regions (Taiwan's northern, northwestern, northeastern, and southeastern regions, as well as the mountainous area); (b) Type 2 (Taiwan's central western and southwestern regions, and the Pescadore Islands); and (c) Type 3 (the Kinmen and Matou Islands). In the GWR models, the response variable of the SIR-district scrub typhus has a statistically significantly positive association with 2 explanatory variables (farm worker population density and timber management). In addition, other explanatory variables (recreational forests, natural reserves, and "other purpose" areas) show positive or negative signs for parameter estimates in various locations in Taiwan. Negative signs of parameter estimates occurred only for the explanatory variables of national protectorates, plantations, and clear-cut areas. The results of this study show that scrub typhus in Taiwan can be classified into 3 types. Type 1 exhibits no climatic effect, whereas the incidence of Type 2 correlates positively with higher temperatures during the warm season, and the incidence of Type 3 correlates positively with higher surface temperatures and longer hours of sunshine. The results also show that in the mountainous township areas of Taiwan's central and southern regions, as well as in Southeastern Taiwan, higher SIR values for scrub typhus are associated with the following variables: farm worker population density, timber management, and area type (i.e., recreational forest, natural reserve, or other purpose).

Scrub typhus islands in the Taiwan area and the association between scrub typhus disease and forest land use and farmer population density: geographically weighted regression

PubMed Central

2013-01-01

Background The Taiwan area comprises the main island of Taiwan and several small islands located off the coast of the Southern China. The eastern two-thirds of Taiwan are characterized by rugged mountains covered with tropical and subtropical vegetation. The western region of Taiwan is characterized by flat or gently rolling plains. Geographically, the Taiwan area is diverse in ecology and environment, although scrub typhus threatens local human populations. In this study, we investigate the effects of seasonal and meteorological factors on the incidence of scrub typhus infection among 10 local climate regions. The correlation between the spatial distribution of scrub typhus and cultivated forests in Taiwan, as well as the relationship between scrub typhus incidence and the population density of farm workers is examined. Methods We applied Pearson’s product moment correlation to calculate the correlation between the incidence of scrub typhus and meteorological factors among 10 local climate regions. We used the geographically weighted regression (GWR) method, a type of spatial regression that generates parameters disaggregated by the spatial units of analysis, to detail and map each regression point for the response variables of the standardized incidence ratio (SIR)-district scrub typhus. We also applied the GWR to examine the explanatory variables of types of forest-land use and farm worker density in Taiwan in 2005. Results In the Taiwan Area, scrub typhus endemic areas are located in the southeastern regions and mountainous townships of Taiwan, as well as the Pescadore, Kinmen, and Matou Islands. Among these islands and low-incidence areas in the central western and southwestern regions of Taiwan, we observed a significant correlation between scrub typhus incidence and surface temperature. No similar significant correlation was found in the endemic areas (e.g., the southeastern region and the mountainous area of Taiwan). Precipitation correlates positively with scrub typhus incidence in 3 local climate regions (i.e., Taiwan’s central western and southwestern regions, and the Kinmen Islands). Relative humidity correlates positively with incidence in Southwestern Taiwan and the Kinmen Islands. The number of wet days correlates positively with incidence in Southwestern Taiwan. The duration of sunshine correlates positively with incidence in Central Western Taiwan, as well as the Kinmen and Matou Islands. In addition, the 10 local climatic regions can be classified into the following 3 groups, based on the warm-cold seasonal fluctuations in scrub typhus incidence: (a) Type 1, evident in 5 local climate regions (Taiwan’s northern, northwestern, northeastern, and southeastern regions, as well as the mountainous area); (b) Type 2 (Taiwan’s central western and southwestern regions, and the Pescadore Islands); and (c) Type 3 (the Kinmen and Matou Islands). In the GWR models, the response variable of the SIR-district scrub typhus has a statistically significantly positive association with 2 explanatory variables (farm worker population density and timber management). In addition, other explanatory variables (recreational forests, natural reserves, and “other purpose” areas) show positive or negative signs for parameter estimates in various locations in Taiwan. Negative signs of parameter estimates occurred only for the explanatory variables of national protectorates, plantations, and clear-cut areas. Conclusion The results of this study show that scrub typhus in Taiwan can be classified into 3 types. Type 1 exhibits no climatic effect, whereas the incidence of Type 2 correlates positively with higher temperatures during the warm season, and the incidence of Type 3 correlates positively with higher surface temperatures and longer hours of sunshine. The results also show that in the mountainous township areas of Taiwan’s central and southern regions, as well as in Southeastern Taiwan, higher SIR values for scrub typhus are associated with the following variables: farm worker population density, timber management, and area type (i.e., recreational forest, natural reserve, or other purpose). PMID:23627966

Serengeti real estate: density vs. fitness-based indicators of lion habitat quality.

PubMed

Mosser, Anna; Fryxell, John M; Eberly, Lynn; Packer, Craig

2009-10-01

Habitat quality is typically inferred by assuming a direct relationship between consumer density and resource abundance, although it has been suggested that consumer fitness may be a more accurate measure of habitat quality. We examined density vs. fitness-based measures of habitat quality for lions in the Serengeti National Park, Tanzania. A 40-year average of female reproductive success (yearling cubs per female) was best explained by proximity to river confluences, whereas patterns of productivity (yearling cubs per km(2)) and adult female density (individuals per km(2)) were associated with more general measures of habitat quality and areas of shelter in poor habitat. This suggests that density may not accurately distinguish between high-quality 'source' areas and low-quality sites that merely provide refuges for effectively non-reproductive individuals. Our results indicate that density may be a misleading indicator of real estate value, particularly for populations that do not conform to an ideal free distribution.

Solar energy in the context of energy use, energy transportation and energy storage.

PubMed

MacKay, David J C

2013-08-13

Taking the UK as a case study, this paper describes current energy use and a range of sustainable energy options for the future, including solar power and other renewables. I focus on the area involved in collecting, converting and delivering sustainable energy, looking in particular detail at the potential role of solar power. Britain consumes energy at a rate of about 5000 watts per person, and its population density is about 250 people per square kilometre. If we multiply the per capita energy consumption by the population density, then we obtain the average primary energy consumption per unit area, which for the UK is 1.25 watts per square metre. This areal power density is uncomfortably similar to the average power density that could be supplied by many renewables: the gravitational potential energy of rainfall in the Scottish highlands has a raw power per unit area of roughly 0.24 watts per square metre; energy crops in Europe deliver about 0.5 watts per square metre; wind farms deliver roughly 2.5 watts per square metre; solar photovoltaic farms in Bavaria, Germany, and Vermont, USA, deliver 4 watts per square metre; in sunnier locations, solar photovoltaic farms can deliver 10 watts per square metre; concentrating solar power stations in deserts might deliver 20 watts per square metre. In a decarbonized world that is renewable-powered, the land area required to maintain today's British energy consumption would have to be similar to the area of Britain. Several other high-density, high-consuming countries are in the same boat as Britain, and many other countries are rushing to join us. Decarbonizing such countries will only be possible through some combination of the following options: the embracing of country-sized renewable power-generation facilities; large-scale energy imports from country-sized renewable facilities in other countries; population reduction; radical efficiency improvements and lifestyle changes; and the growth of non-renewable low-carbon sources, namely 'clean' coal, 'clean' gas and nuclear power. If solar is to play a large role in the future energy system, then we need new methods for energy storage; very-large-scale solar either would need to be combined with electricity stores or it would need to serve a large flexible demand for energy that effectively stores useful energy in the form of chemicals, heat, or cold.

The Urban/Rural Dichotomy in the Distribution of Breast Cancer Across Pennsylvania.

PubMed

Boukovalas, Stefanos; Sariego, Jack

2015-09-01

Breast cancer rates clearly differ across the United States. This is due to a variety of factors, but at least one determinant is the population density. Breast cancer detection rates and treatment paradigms may differ in rural areas when compared with more urban ones. As the population becomes more mobile and diffuse, this may or may not be a worsening problem. The current analysis was undertaken to examine the breast cancer incidence and outcomes in a single state in an attempt to plan for resource allocation in the future. A retrospective analysis was performed using data available from the Pennsylvania Department of Health regarding breast cancer rates by county, the distribution of cases with regard to degree of rurality, death rates by county as a function of rurality, and the age distribution of all presenting cases. Data from 1999 were compared with those of 2009. The United States Census Bureau definition of rurality was used, which specifies that a county be classified as rural if the population density is less than 284 persons/square mile. Between 1999 and 2009, the population of Pennsylvania increased by approximately 3.4 per cent (421,325 people). The urban population increased by 3.9 per cent, whereas the rural population increased by only 2.2 per cent. During that same period, the number of cancer cases/100,000 population remained about the same: 391.41 in 1999; 390.7 in 2009. However, the distribution of cases shifted during that time toward more rural areas of the state: in 1999, there were 372.3 breast cancer cases/100,000 population compared with 2009 when the rate was 384.4/100,000 population. The number of cancer deaths/100,000 population actually dropped overall during the decade: 98.5 in 1999 versus 82.3 in 2009. Though this was true in both urban and rural counties, the decrease was much less pronounced in the rural areas. In urban counties, the death rate dropped from 100.5 to 81.5/100,000 population, whereas in rural counties, the drop was only from 93.3 to 84.3. The greater increase in cases diagnosed in rural areas of Pennsylvania is only partially explained by the relatively greater increase in rural population. There are undoubtedly other issues at work in rural areas: environmental factors, diffusion of resources, less access to surveillance programs. In addition, though the death rate has dropped in both rural and urban areas, this is much less pronounced in rural counties. Coupled with the increase in prevalence in those areas, this suggests that breast cancer care may be lagging in rural areas. There is a need to examine allocation of resources and surveillance programs.

Cougar response to a gradient of human development

DOE PAGES

Maletzke, Benjamin; Kertson, Brian; Swanson, Mark; ...

2017-07-07

Human populations continue to increase and transform Earth's ecosystems. For large carnivores, human development reduces habitat abundance, alters predator–prey dynamics, and increases the risk of mortality, which may threaten the viability of many populations. To investigate how the cougar ( Puma concolor) responds to a gradient of human development in four areas in Washington, USA, we used utilization distributions, county tax parcel data, Weibull modeling analysis, and multiple comparison techniques. Cougars used wildland areas the majority of the time (79% ± 2%, n = 112 cougars), with use decreasing as housing densities increased. When present in human-developed areas in easternmore » Washington, 99% of the habitat that cougars used had housing densities ≤76.5 residences/km 2, which was <846.0 residences/km 2 observed in western Washington ( P < 0.01). Cougars used areas in western Washington with greater housing density likely because of the clustered nature of housing developments, the connectivity with greenbelts and forested corridors, and security cover of dense maritime vegetation. Our findings suggest a consistent, albeit nuanced response by cougars to human development that may be used by wildlife managers, landscape planners, and environmental educators to guide and enhance their efforts to minimize the impacts of human development on cougars and reduce the potential for conflicts with people. In conclusion, our model may also provide guidance for thresholds of human development for other adaptable large carnivores.« less

Cougar response to a gradient of human development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maletzke, Benjamin; Kertson, Brian; Swanson, Mark

Human populations continue to increase and transform Earth's ecosystems. For large carnivores, human development reduces habitat abundance, alters predator–prey dynamics, and increases the risk of mortality, which may threaten the viability of many populations. To investigate how the cougar ( Puma concolor) responds to a gradient of human development in four areas in Washington, USA, we used utilization distributions, county tax parcel data, Weibull modeling analysis, and multiple comparison techniques. Cougars used wildland areas the majority of the time (79% ± 2%, n = 112 cougars), with use decreasing as housing densities increased. When present in human-developed areas in easternmore » Washington, 99% of the habitat that cougars used had housing densities ≤76.5 residences/km 2, which was <846.0 residences/km 2 observed in western Washington ( P < 0.01). Cougars used areas in western Washington with greater housing density likely because of the clustered nature of housing developments, the connectivity with greenbelts and forested corridors, and security cover of dense maritime vegetation. Our findings suggest a consistent, albeit nuanced response by cougars to human development that may be used by wildlife managers, landscape planners, and environmental educators to guide and enhance their efforts to minimize the impacts of human development on cougars and reduce the potential for conflicts with people. In conclusion, our model may also provide guidance for thresholds of human development for other adaptable large carnivores.« less

Rhizobacterial population density and nitrogen fixation in seagrass community of Gulf of Mannar, India.

PubMed

Raja, S; Thangaradjou, T; Sivakumar, K; Kannan, L

2012-11-01

Seagrass rhizosphere generally supports high bacterial population density which plays a major role in determining the nutrient cycles of the sea. Higher densities of total heterotrphic bacteria (26.3 x 10(6) CFU g(-1)), nitrogen fixing (27.3 x 10(3) CFUg(-1), ammonifying (44.66 x 10(6) MPN g(-1)) and nitrifying bacteria (42.33 X 10(6) MPN g(-1)) have been registered in the seagrass areas than the non seagrass area. In particular, all these rhizosphere microbial population was higher in Thalassia hemprichii. The rates of nitrogen fixation was recorded in the different species of seagrasses such as Enhalus acoroides (1.166 n mol g(-1) d(-1)), Halophila ovalis (0.166 n mol g(-1) d(-1)), Thalassia hemprichii(18.5 n mol g(-1) d(-1)), Cymodocea serrulata (10.5 n mol g(-1) d(-1)), Halodule uninervis (5.375 n mol g(-1) d(-1)) and Syringodium isoetifolium (0.666 n mol g(-1) d(-1)) using gas chromatography. The average nitrogen fixation by the seagrasses of Gulf of Mannar alone was estimated to be 7640.58 n mol m(-2) d(-1) and the contributions from the rhizosphere microbes will increase the quantity to many fold.

Estimating black bear population density and genetic diversity at Tensas River, Louisiana using microsatellite DNA markers

USGS Publications Warehouse

Boersen, Mark R.; Clark, Joseph D.; King, Tim L.

2003-01-01

The Recovery Plan for the federally threatened Louisiana black bear (Ursus americanus luteolus) mandates that remnant populations be estimated and monitored. In 1999 we obtained genetic material with barbed-wire hair traps to estimate bear population size and genetic diversity at the 329-km2 Tensas River Tract, Louisiana. We constructed and monitored 122 hair traps, which produced 1,939 hair samples. Of those, we randomly selected 116 subsamples for genetic analysis and used up to 12 microsatellite DNA markers to obtain multilocus genotypes for 58 individuals. We used Program CAPTURE to compute estimates of population size using multiple mark-recapture models. The area of study was almost entirely circumscribed by agricultural land, thus the population was geographically closed. Also, study-area boundaries were biologically discreet, enabling us to accurately estimate population density. Using model Chao Mh to account for possible effects of individual heterogeneity in capture probabilities, we estimated the population size to be 119 (SE=29.4) bears, or 0.36 bears/km2. We were forced to examine a substantial number of loci to differentiate between some individuals because of low genetic variation. Despite the probable introduction of genes from Minnesota bears in the 1960s, the isolated population at Tensas exhibited characteristics consistent with inbreeding and genetic drift. Consequently, the effective population size at Tensas may be as few as 32, which warrants continued monitoring or possibly genetic augmentation.

Urban Growth in Cairo 1965-98

NASA Technical Reports Server (NTRS)

2002-01-01

The population of the Cairo metropolitan area has increased from less than 6 million in 1965 when the first picture was taken, to more than 10 million in 1998 (United Nations Population Division, World Urbanization Prospects, the 1999 revision). Population densities within the city are some of the highest in the world and the urban area has doubled to more than 400 square km during that period. Extraordinary rates of population growth are expected to continue, with a predicted population of around 14 million by 2015. Images Gem05-1-45778 and STS088-739-91 were provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

Dispersal patterns of red foxes relative to population density

USGS Publications Warehouse

Allen, Stephen H.; Sargeant, Alan B.

1993-01-01

Factors affecting red fox (Vulpes vulpes) dispersal patterns are poorly understood but warranted investigation because of the role of dispersal in rebuilding depleted populations and transmission of diseases. We examined dispersal patterns of red foxes in North Dakota based on recoveries of 363 of 854 foxes tagged as pups and relative to fox density. Foxes were recovered up to 8.6 years after tagging; 79% were trapped or shot. Straight-line distances between tagging and recovery locations ranged from 0 to 302 km. Mean recovery distances increased with age and were greater for males than females, but longest individual recovery distances were by females. Dispersal distances were not related to population density for males (P = 0.36) or females (P = 0.96). The proportion of males recovered that dispersed was inversely related to population density (r = -0.94; n = 5; P = 0.02), but not the proportion of females (r = -0.49; n = 5; P = 0.40). Dispersal directions were not uniform for either males (P = 0.003) or females (P = 0.006); littermates tended to disperse in similar directions (P = 0.09). A 4-lane interstate highway altered dispersal directions (P = 0.001). Dispersal is a strong innate behavior of red foxes (especially males) that results in many individuals of both sexes traveling far from natal areas. Because dispersal distance was unaffected by fox density, populations can be rebuilt and diseases transmitted long distances regardless of fox abundance.

DENSITY: software for analysing capture-recapture data from passive detector arrays

USGS Publications Warehouse

Efford, M.G.; Dawson, D.K.; Robbins, C.S.

2004-01-01

A general computer-intensive method is described for fitting spatial detection functions to capture-recapture data from arrays of passive detectors such as live traps and mist nets. The method is used to estimate the population density of 10 species of breeding birds sampled by mist-netting in deciduous forest at Patuxent Research Refuge, Laurel, Maryland, U.S.A., from 1961 to 1972. Total density (9.9 ? 0.6 ha-1 mean ? SE) appeared to decline over time (slope -0.41 ? 0.15 ha-1y-1). The mean precision of annual estimates for all 10 species pooled was acceptable (CV(D) = 14%). Spatial analysis of closed-population capture-recapture data highlighted deficiencies in non-spatial methodologies. For example, effective trapping area cannot be assumed constant when detection probability is variable. Simulation may be used to evaluate alternative designs for mist net arrays where density estimation is a study goal.

Concepts and practices: Estimating abundance of prey species using hierarchical model-based approaches

USGS Publications Warehouse

Dorazio, Robert; Kumar, N. Samba; Royle, Andy; Gopalaswamy, Arjun M.

2017-01-01

Tigers predominantly prey on large ungulate species, such as sambar (Cervus unicolor), red deer (Cervus elaphus), gaur (Bos gaurus), banteng (Bos javanicus), chital (Axis axis), muntjac (Muntiacus muntjak), wild pig (Sus scrofa), and bearded pig (Sus barbatus). The density of a tiger population is strongly correlated with the density of such prey species (Karanth et al. 2004). In the absence of direct hunting of tigers, abundance of prey in an area is the key determinant of the “carrying capacity” of that area for tigers (Chap. 2). Accurate estimates of prey abundance are often needed to assess the potential number of tigers a conservation area can support.

Health-Related Quality of Life and Health Behaviors in a Population-Based Sample of Older, Foreign-Born, Chinese American Adults Living in New York City

ERIC Educational Resources Information Center

Wyatt, Laura C.; Trinh-Shevrin, Chau; Islam, Nadia S.; Kwon, Simona C.

2014-01-01

Although the New York City Chinese population aged =65 years increased by 50% between 2000 and 2010, the health needs of this population are poorly understood. Approximately 3,001 Chinese individuals from high-density Asian American New York City areas were included in the REACH U.S. Risk Factor Survey; 805 (26.8%) were aged =65 years and…

A regional assessment of medicaid access to outpatient orthopaedic care: the influence of population density and proximity to academic medical centers on patient access.

PubMed

Patterson, Brendan M; Draeger, Reid W; Olsson, Erik C; Spang, Jeffrey T; Lin, Feng-Chang; Kamath, Ganesh V

2014-09-17

Access to care is limited for patients with Medicaid with many conditions, but data investigating this relationship in the orthopaedic literature are limited. The purpose of this study was to investigate the relationship between health insurance status and access to care for a diverse group of adult orthopaedic patients, specifically if access to orthopaedic care is influenced by population density or distance from academic teaching hospitals. Two hundred and three orthopaedic practices within the state of North Carolina were randomly selected and were contacted on two different occasions separated by three weeks. An appointment was requested for a fictitious adult orthopaedic patient with a potential surgical problem. Injury scenarios included patients with acute rotator cuff tears, zone-II flexor tendon lacerations, and acute lumbar disc herniations. Insurance status was reported as Medicaid at the time of the first request and private insurance at the time of the second request. County population density and the distance from each practice to the nearest academic hospital were recorded. Of the 203 practices, 119 (59%) offered the patient with Medicaid an appointment within two weeks, and 160 (79%) offered the patient with private insurance an appointment within this time period (p < 0.001). Practices in rural counties were more likely to offer patients with Medicaid an appointment as compared with practices in urban counties (odds ratio, 2.25 [95% confidence interval, 1.16 to 4.34]; p = 0.016). Practices more than sixty miles from academic hospitals were more likely to accept patients with Medicaid than practices closer to academic hospitals (odds ratio, 3.35 [95% confidence interval, 1.44 to 7.83]; p = 0.005). Access to orthopaedic care was significantly decreased for patients with Medicaid. Practices in less populous areas were more likely to offer an appointment to patients with Medicaid than practices in more populous areas. Practices that were farther from academic hospitals were more likely to offer an appointment to patients with Medicaid than practices closer to academic hospitals. This study illustrates the barriers to timely outpatient orthopaedic care that patients with Medicaid face. The findings from our study imply that patients with Medicaid in more populous areas and in areas closer to academic medical centers are less likely to obtain an outpatient orthopaedic appointment than patients with Medicaid in less populous areas and in areas more distant from academic medical centers. A shift in policy to enhance access to orthopaedic care for patients with Medicaid, especially those in urban areas and areas close to academic medical centers, will become increasingly important as more patients become eligible for Medicaid through the Patient Protection and Affordable Care Act of 2010. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Spatial heterogeneity in the carrying capacity of sika deer in Japan

PubMed Central

Iijima, Hayato; Ueno, Mayumi

2016-01-01

Abstract Carrying capacity is 1 driver of wildlife population dynamics. Although in previous studies carrying capacity was considered to be a fixed entity, it may differ among locations due to environmental variation. The factors underlying variability in carrying capacity, however, have rarely been examined. Here, we investigated spatial heterogeneity in the carrying capacity of Japanese sika deer ( Cervus nippon ) from 2005 to 2014 in Yamanashi Prefecture, central Japan (mesh with grid cells of 5.5×4.6 km) by state-space modeling. Both carrying capacity and density dependence differed greatly among cells. Estimated carrying capacities ranged from 1.34 to 98.4 deer/km 2 . According to estimated population dynamics, grid cells with larger proportions of artificial grassland and deciduous forest were subject to lower density dependence and higher carrying capacity. We conclude that population dynamics of ungulates may vary spatially through spatial variation in carrying capacity and that the density level for controlling ungulate abundance should be based on the current density level relative to the carrying capacity for each area. PMID:29692470

Clinal patterns in genetic variation for northern leopard frog (Rana pipiens): Conservation status and population histories

USGS Publications Warehouse

Stockwell, Craig A.; Fisher, Justin D.L.; McLean, Kyle I.

2016-01-01

The security of the northern leopard frog (Rana pipiens) varies spatially with populations east and west of North Dakota considered as secure and at risk, respectively. We used genetic markers to characterize the conservation status of northern leopard frog populations across North Dakota. We used multiple regression analyses and model selection to evaluate correlations of expected heterozygosity (HE) with the direct and additive effects of: i) geographic location,ii) wetland density and iii) average annual precipitation. There was lower genetic diversity in the western portion of the state due to lower levels of diversity for populations southwest of the Missouri River. This may reflect a refugial/colonization signature for the only non-glaciated area of North Dakota. Genetic diversity was also positively associated with wetland densities which is consistent with the reliance of this species on a mosaic of wetlands. Our findings suggest that populations in the southwestern part of North Dakota are of higher conservation concern, a finding consistent with the higher risk noted for northern leopard frog populations in most states west of North Dakota. Our findings also pose the hypothesis that climate change induced changes in wetland densities will reduce genetic diversity of northern leopard frog populations.

Clinical malaria case definition and malaria attributable fraction in the highlands of western Kenya.

PubMed

Afrane, Yaw A; Zhou, Guofa; Githeko, Andrew K; Yan, Guiyun

2014-10-15

In African highland areas where endemicity of malaria varies greatly according to altitude and topography, parasitaemia accompanied by fever may not be sufficient to define an episode of clinical malaria in endemic areas. To evaluate the effectiveness of malaria interventions, age-specific case definitions of clinical malaria needs to be determined. Cases of clinical malaria through active case surveillance were quantified in a highland area in Kenya and defined clinical malaria for different age groups. A cohort of over 1,800 participants from all age groups was selected randomly from over 350 houses in 10 villages stratified by topography and followed for two-and-a-half years. Participants were visited every two weeks and screened for clinical malaria, defined as an individual with malaria-related symptoms (fever [axillary temperature≥37.5°C], chills, severe malaise, headache or vomiting) at the time of examination or 1-2 days prior to the examination in the presence of a Plasmodium falciparum positive blood smear. Individuals in the same cohort were screened for asymptomatic malaria infection during the low and high malaria transmission seasons. Parasite densities and temperature were used to define clinical malaria by age in the population. The proportion of fevers attributable to malaria was calculated using logistic regression models. Incidence of clinical malaria was highest in valley bottom population (5.0% cases per 1,000 population per year) compared to mid-hill (2.2% cases per 1,000 population per year) and up-hill (1.1% cases per 1,000 population per year) populations. The optimum cut-off parasite densities through the determination of the sensitivity and specificity showed that in children less than five years of age, 500 parasites per μl of blood could be used to define the malaria attributable fever cases for this age group. In children between the ages of 5-14, a parasite density of 1,000 parasites per μl of blood could be used to define the malaria attributable fever cases. For individuals older than 14 years, the cut-off parasite density was 3,000 parasites per μl of blood. Clinical malaria case definitions are affected by age and endemicity, which needs to be taken into consideration during evaluation of interventions.

Population Dynamics of an Insect Herbivore over 32 Years are Driven by Precipitation and Host-Plant Effects: Testing Model Predictions.

PubMed

Price, Peter W; Hunter, Mark D

2015-06-01

The interaction between the arroyo willow, Salix lasiolepis Bentham, and its specialist herbivore, the arroyo willow stem-galling sawfly, Euura lasiolepis Smith (Hymenoptera: Tenthredinidae), was studied for 32 yr in Flagstaff, AZ, emphasizing a mechanistic understanding of insect population dynamics. Long-term weather records were evaluated to provide a climatic context for this study. Previously, predictive models of sawfly dynamics were developed from estimates of sawfly gall density made between 1981 and 2002; one model each for drier and wetter sites. Predictor variables in these models included winter precipitation and the Palmer Drought Severity Index, which impact the willow growth, with strong bottom-up effects on sawflies. We now evaluate original model predictions of sawfly population dynamics using new data (from 2003-2012). Additionally, willow resources were evaluated in 1986 and in 2012, using as criteria clone area, shoot density, and shoot length. The dry site model accounted for 40% of gall population density variation between 2003 and 2012 (69% over the 32 yr), providing strong support for the bottom-up, mechanistic hypothesis that water supply to willow hosts impacts sawfly populations. The current drying trend stressed willow clones: in drier sites, willow resources declined and gall density decreased by 98%. The wet site model accounted for 23% of variation in gall population density between 2003 and 2012 (48% over 30 yr), consistent with less water limitation. Nonetheless, gall populations were reduced by 72%. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Using the LCZ framework for change detection and urban growth monitoring

NASA Astrophysics Data System (ADS)

Danylo, Olha; See, Linda; Gomez, Adriana; Schnabel, Georg; Fritz, Steffen

2017-04-01

The world's population reached 7.3 billion in 2015 and it is projected to increase further to 9.7 billion by 2050. Population growth is strongly linked to city expansion, as many people are moving from rural to urban areas. In order to enhance inclusive and sustainable urbanization, we need an efficient workflow for assessing the corresponding SDG (Sustainable Development Goal) targets. In this study we investigate how the Local Climate Zone (LCZ) classification framework can be used for monitoring sustainable urbanization and assess the availability of adequate and safe housing. The original LCZ classification system consists of 10 urban classes, which can be characterized by urban structure, the type of roads and buildings, the density of the built-up area, etc. The other seven classes in the classification scheme include natural land cover classes that do not contain any buildings (e.g., forest, low vegetation, bare land, water, etc). As a case study area we have chosen the cities of Johannesburg and Pretoria in South Africa. According to the 2011 Census, the population of Gauteng province (which includes both Johannesburg and Pretoria) increased by 32.55% compared to 2001 Census and reached 12 million in 2011. A large number of people live in slums and informal housing, which makes this area relevant for such an analysis. Using available satellite images for different years, we classified the case-study areas into the main LCZ classes, including the lightweight lowrise building zone, which corresponds to informal housing. We estimated the land use efficiency as the ratio of the land consumption rate to the population growth rate to illustrate how the LCZ framework can be applied to the assessment of urban growth and to help understand the trajectories of the changes in the urban environment. We show that a low value of this ratio does not necessarily indicate sustainable city expansion, but may instead signal a growing population density in the slum areas.

Longitudinal Association of Anthropometry with Mammographic Breast Density in the Study of Women's Health Across the Nation (Swan)

PubMed Central

Reeves, Katherine W.; Stone, Roslyn A.; Modugno, Francesmary; Ness, Roberta B.; Vogel, Victor G.; Weissfeld, Joel L.; Habel, Laurel A.; Sternfeld, Barbara; Cauley, Jane A.

2009-01-01

High percent mammographic breast density is strongly associated with increased breast cancer risk. Though body mass index (BMI) is positively associated with risk of postmenopausal breast cancer, BMI is negatively associated with percent breast density in cross-sectional studies. Few longitudinal studies have evaluated associations between BMI and weight and mammographic breast density. We studied the longitudinal relationships between anthropometry and breast density in a prospective cohort of 834 pre- and perimenopausal women enrolled in an ancillary study to the Study of Women's Health Across the Nation (SWAN). Routine screening mammograms were collected and read for breast density. Random intercept regression models were used to evaluate whether annual BMI change was associated with changes over time in dense breast area and percent density. The study population was 7.4% African American, 48.8% Caucasian, 21.8% Chinese, and 21.9% Japanese. Mean follow-up was 4.8 years. Mean annual weight change was +0.32 kg/year, mean change in dense area was -0.77 cm2/year, and mean change in percent density was -1.14%/year. In fully adjusted models, annual change in BMI was not significantly associated with changes in dense breast area (-0.17 cm2, 95% CI -0.64, 0.29). Borderline significant negative associations were observed between annual BMI change and annual percent density change, with percent density decreasing 0.36% (95% CI -0.74, 0.02) for a one unit increase in BMI over a year. This longitudinal study provides modest evidence that changes in BMI are not associated with changes in dense area, yet may be negatively associated with percent density. PMID:19065651

Arterial roads and area socioeconomic status are predictors of fast food restaurant density in King County, WA

PubMed Central

Hurvitz, Philip M; Moudon, Anne V; Rehm, Colin D; Streichert, Laura C; Drewnowski, Adam

2009-01-01

Background Fast food restaurants reportedly target specific populations by locating in lower-income and in minority neighborhoods. Physical proximity to fast food restaurants has been associated with higher obesity rates. Objective To examine possible associations, at the census tract level, between area demographics, arterial road density, and fast food restaurant density in King County, WA, USA. Methods Data on median household incomes, property values, and race/ethnicity were obtained from King County and from US Census data. Fast food restaurant addresses were obtained from Public Health-Seattle & King County and were geocoded. Fast food density was expressed per tract unit area and per capita. Arterial road density was a measure of vehicular and pedestrian access. Multivariate logistic regression models containing both socioeconomic status and road density were used in data analyses. Results Over one half (53.1%) of King County census tracts had at least one fast food restaurant. Mean network distance from dwelling units to a fast food restaurant countywide was 1.40 km, and 1.07 km for census tracts containing at least one fast food restaurant. Fast food restaurant density was significantly associated in regression models with low median household income (p < 0.001) and high arterial road density (p < 0.001) but not with percent of residents who were nonwhite. Conclusion No significant association was observed between census tract minority status and fast food density in King County. Although restaurant density was linked to low household incomes, that effect was attenuated by arterial road density. Fast food restaurants in King County are more likely to be located in lower income neighborhoods and higher traffic areas. PMID:19630979

Modelling the structural response of cotton plants to mepiquat chloride and population density

PubMed Central

Gu, Shenghao; Evers, Jochem B.; Zhang, Lizhen; Mao, Lili; Zhang, Siping; Zhao, Xinhua; Liu, Shaodong; van der Werf, Wopke; Li, Zhaohu

2014-01-01

Background and Aims Cotton (Gossypium hirsutum) has indeterminate growth. The growth regulator mepiquat chloride (MC) is used worldwide to restrict vegetative growth and promote boll formation and yield. The effects of MC are modulated by complex interactions with growing conditions (nutrients, weather) and plant population density, and as a result the effects on plant form are not fully understood and are difficult to predict. The use of MC is thus hard to optimize. Methods To explore crop responses to plant density and MC, a functional–structural plant model (FSPM) for cotton (named CottonXL) was designed. The model was calibrated using 1 year's field data, and validated by using two additional years of detailed experimental data on the effects of MC and plant density in stands of pure cotton and in intercrops of cotton with wheat. CottonXL simulates development of leaf and fruits (square, flower and boll), plant height and branching. Crop development is driven by thermal time, population density, MC application, and topping of the main stem and branches. Key Results Validation of the model showed good correspondence between simulated and observed values for leaf area index with an overall root-mean-square error of 0·50 m2 m−2, and with an overall prediction error of less than 10 % for number of bolls, plant height, number of fruit branches and number of phytomers. Canopy structure became more compact with the decrease of leaf area index and internode length due to the application of MC. Moreover, MC did not have a substantial effect on boll density but increased lint yield at higher densities. Conclusions The model satisfactorily represents the effects of agronomic measures on cotton plant structure. It can be used to identify optimal agronomic management of cotton to achieve optimal plant structure for maximum yield under varying environmental conditions. PMID:24489020

Development of a spatially distributed model of fish population density for habitat assessment of rivers

NASA Astrophysics Data System (ADS)

Sui, Pengzhe; Iwasaki, Akito; Ryo, Masahiro; Saavedra, Oliver; Yoshimura, Chihiro

2013-04-01

Flow conditions play an important role in sustaining biodiversity of river ecosystem. However, their relations to freshwater fishes, especially to fish population density, have not been clearly described. This study, therefore, aimed to propose a new methodology to quantitatively link habitat conditions, including flow conditions and other physical conditions, to population density of fish species. We developed a basin-scale fish distribution model by integrating the concept of habitat suitability assessment with a distributed hydrological model (DHM) in order to estimate fish population density with particular attention to flow conditions. Generalized linear model (GLM) was employed to evaluate the relationship between population density of fish species and major environmental factors. The target basin was Sagami River in central Japan, where the river reach was divided into 10 sections by estuary, confluences of tributaries, and river-crossing structures (dams, weirs). The DHM was employed to simulate river discharge from 1998 to 2005, which was used to calculate 10 flow indices including mean discharge, 25th and 75th percentile discharge, duration of low and high flows, number of floods. In addition, 5 water quality parameters and 13 other physical conditions (such as basin area, river width, mean diameter of riverbed material, and number of river-crossing structures upstream and downstream) of each river section were considered as environmental variables. In case of Sagami River, 10 habitat variables among them were then selected based on their correlations to avoid multicollinearity. Finally, the best GLM was developed for each species based on Akaike's information criterion. As results, population densities of 16 fish species in Sagami River were modelled, and correlation coefficients between observed and calculated population densities for 10 species were more than 0.70. The key habitat factors for population density varied among fish species. Minimum discharge (MID) was found to be positively correlated to 9 among 16 fish species. For duration of high and low flows (DHF and DLF), longer DHF/DLF was corresponded to lower population density for 7/6 fish species, respectively, such as Rhinogobius kurodai and Plecoglossus altivelis altivelis. Among physical habitat conditions, sinuosity index (SI, the ratio between actual river section length and straight line length) seems to be the most important parameter for fish population density in Sagami River basin, since it affects 12 out of 16 fish species, followed by mean longitudinal slope (S) and number of downstream dams (NLD). Above results demonstrated the applicability of fish distribution model to provide quantitative information on flow conditions required to maintain fish population, which enabled us to evaluate and project ecological consequences of water resource management policy, such as flood management and water withdrawal.

Identifying Population Vulnerable to Extreme Heat Events in San Jose, California.

NASA Astrophysics Data System (ADS)

Rivera, A. L.

2016-12-01

The extreme heat days not only make cities less comfortable for living but also they are associated with increased morbidity and mortality. Mapping studies have demonstrated spatial variability in heat vulnerability. A study conducted between 2000 and 2011 in New York City shows that deaths during heat waves was more likely to occur in black individuals, at home in census tracts which received greater public assistance. This map project intends to portray areas in San Jose California that are vulnerable to extreme heat events. The variables considered to build a vulnerability index are: land surface temperature, vegetated areas (NDVI), and people exposed to these area (population density).

Does transport time help explain the high trauma mortality rates in rural areas? New and traditional predictors assessed by new and traditional statistical methods

PubMed Central

Røislien, Jo; Lossius, Hans Morten; Kristiansen, Thomas

2015-01-01

Background Trauma is a leading global cause of death. Trauma mortality rates are higher in rural areas, constituting a challenge for quality and equality in trauma care. The aim of the study was to explore population density and transport time to hospital care as possible predictors of geographical differences in mortality rates, and to what extent choice of statistical method might affect the analytical results and accompanying clinical conclusions. Methods Using data from the Norwegian Cause of Death registry, deaths from external causes 1998–2007 were analysed. Norway consists of 434 municipalities, and municipality population density and travel time to hospital care were entered as predictors of municipality mortality rates in univariate and multiple regression models of increasing model complexity. We fitted linear regression models with continuous and categorised predictors, as well as piecewise linear and generalised additive models (GAMs). Models were compared using Akaike's information criterion (AIC). Results Population density was an independent predictor of trauma mortality rates, while the contribution of transport time to hospital care was highly dependent on choice of statistical model. A multiple GAM or piecewise linear model was superior, and similar, in terms of AIC. However, while transport time was statistically significant in multiple models with piecewise linear or categorised predictors, it was not in GAM or standard linear regression. Conclusions Population density is an independent predictor of trauma mortality rates. The added explanatory value of transport time to hospital care is marginal and model-dependent, highlighting the importance of exploring several statistical models when studying complex associations in observational data. PMID:25972600

Effect of experimental manipulation on survival and recruitment of feral pigs

USGS Publications Warehouse

Hanson, L.B.; Mitchell, M.S.; Grand, J.B.; Jolley, D.B.; Sparklin, B.D.; Ditchkoff, S.S.

2009-01-01

Lethal removal is commonly used to reduce the density of invasive-species populations, presuming it reduces population growth rate; the actual effect of lethal removal on the vital rates contributing to population growth, however, is rarely tested. We implemented a manipulative experiment of feral pig (Sus scrofa) populations at Fort Benning, Georgia, USA, to assess the demographic effects of harvest intensity. Using markrecapture data, we estimated annual survival, recruitment, and population growth rates of populations in a moderately harvested area and a heavily harvested area for 200406. Population growth rates did not differ between the populations. The top-ranked model for survival included a harvest intensity effect; model-averaged survival was lower for the heavily harvested population than for the moderately harvested population. Increased immigration and reproduction likely compensated for the increased mortality in the heavily harvested population. We conclude that compensatory responses in feral pig recruitment can limit the success of lethal control efforts. ?? 2009 CSIRO.

Density of loons in central Alaska

USGS Publications Warehouse

Lanctot, Richard B.; Quang, Pham Xuan

1992-01-01

Loons breed across North America from the high arctic south to about 43 north latitude. (AOU 1983). Populations, particularly of Common Loons (Gavia immer) have recently declined in the continental U.S. and southern Canada (Sutcliff 1979, Titus and VanDruff 1981, McIntyre 1988). As a result, state and private natural resource organizations began more intensive monitoring of loon populations (in McIntyre 1986, Strong 1988). These surveys, however, are restricted to areas accessible by road, although recently aircraft were used for more remote areas (Lee and Arbuckle 1988, Strong 1990).

The Broadband Quandary for Rural America. The Main Street Economist: Commentary on the Rural Economy.

ERIC Educational Resources Information Center

Staihr, Brian

High speed data services known as broadband have the potential to make rural areas less isolated and improve the rural quality of life, but physical barriers, sparse population density, and few markets present significant obstacles to their deployment in rural areas. Broadband applications such as e-commerce, distance education, and telemedicine…

78 FR 77153 - Environmental Action Statement Screening Form and Proposed Amendment to the Candidate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-20

... by domestic livestock, oil and gas development, wind energy development, loss of native rangelands to... birds protected on enrolled lands. If, on average, LEPC densities are about two birds per square mile in.../implementation area of this CCAA and an overall population of about 3,125 birds within the entire planning area...

The Attunement Principles: A Comparison of Nurture Group and Mainstream Settings

ERIC Educational Resources Information Center

Cubeddu, Daniela; MacKay, Tommy

2017-01-01

Two key areas identified for research are differences in practice between nurture groups and mainstream classrooms, and nurturing approaches in rural and low-density populations. This study compared classroom practice in a nurture group serving a wide rural area with the four mainstream classes to which the five children in the group belonged. The…

Landscape models of adult coho salmon density examined at four spatial extents

Treesearch

Julie C. Firman; E. Ashley Steel; David W. Jensen; Kelly M. Burnett; Kelly Christiansen; Blake E. Feist; David P. Larsen; Kara Anlauf

2011-01-01

Salmon occupy large areas over which comprehensive surveys are not feasible owing to the prohibitive expense of surveying thousands of kilometers of streams. Studies of these populations generally rely on sampling a small portion of the distribution of the species. However, managers often need information about areas that have not been visited. The availability of...

Wireless Sensor Networks - Node Localization for Various Industry Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Derr, Kurt; Manic, Milos

Fast, effective monitoring following airborne releases of toxic substances is critical to mitigate risks to threatened population areas. Wireless sensor nodes at fixed predetermined locations may monitor such airborne releases and provide early warnings to the public. A challenging algorithmic problem is determining the locations to place these sensor nodes while meeting several criteria: 1) provide complete coverage of the domain, and 2) create a topology with problem dependent node densities, while 3) minimizing the number of sensor nodes. This manuscript presents a novel approach to determining optimal sensor placement, Advancing Front mEsh generation with Constrained dElaunay Triangulation and Smoothingmore » (AFECETS) that addresses these criteria. A unique aspect of AFECETS is the ability to determine wireless sensor node locations for areas of high interest (hospitals, schools, high population density areas) that require higher density of nodes for monitoring environmental conditions, a feature that is difficult to find in other research work. The AFECETS algorithm was tested on several arbitrary shaped domains. AFECETS simulation results show that the algorithm 1) provides significant reduction in the number of nodes, in some cases over 40%, compared to an advancing front mesh generation algorithm, 2) maintains and improves optimal spacing between nodes, and 3) produces simulation run times suitable for real-time applications.« less

Wireless Sensor Networks - Node Localization for Various Industry Problems

DOE PAGES

Derr, Kurt; Manic, Milos

2015-06-01

Fast, effective monitoring following airborne releases of toxic substances is critical to mitigate risks to threatened population areas. Wireless sensor nodes at fixed predetermined locations may monitor such airborne releases and provide early warnings to the public. A challenging algorithmic problem is determining the locations to place these sensor nodes while meeting several criteria: 1) provide complete coverage of the domain, and 2) create a topology with problem dependent node densities, while 3) minimizing the number of sensor nodes. This manuscript presents a novel approach to determining optimal sensor placement, Advancing Front mEsh generation with Constrained dElaunay Triangulation and Smoothingmore » (AFECETS) that addresses these criteria. A unique aspect of AFECETS is the ability to determine wireless sensor node locations for areas of high interest (hospitals, schools, high population density areas) that require higher density of nodes for monitoring environmental conditions, a feature that is difficult to find in other research work. The AFECETS algorithm was tested on several arbitrary shaped domains. AFECETS simulation results show that the algorithm 1) provides significant reduction in the number of nodes, in some cases over 40%, compared to an advancing front mesh generation algorithm, 2) maintains and improves optimal spacing between nodes, and 3) produces simulation run times suitable for real-time applications.« less

The association between higher nurse staffing standards in the fee schedules and the geographic distribution of hospital nurses: A cross-sectional study using nationwide administrative data.

PubMed

Morioka, Noriko; Tomio, Jun; Seto, Toshikazu; Kobayashi, Yasuki

2017-01-01

In Japan, the revision of the fee schedules in 2006 introduced a new category of general care ward for more advanced care, with a higher staffing standard, a patient-to-nurse ratio of 7:1. Previous studies have suggested that these changes worsened inequalities in the geographic distribution of nurses, but there have been few quantitative studies evaluating this effect. This study aimed to investigate the association between the distribution of 7:1 beds and the geographic distribution of hospital nursing staffs. We conducted a secondary data analysis of hospital reimbursement reports in 2012 in Japan. The study units were secondary medical areas (SMAs) in Japan, which are roughly comparable to hospital service areas in the United States. The outcome variable was the nurse density per 100,000 population in each SMA. The 7:1 bed density per 100,000 population was the main independent variable. To investigate the association between the nurse density and 7:1 bed density, adjusting for other variables, we applied a multiple linear regression model, with nurse density as an outcome variable, and the bed densities by functional category of inpatient ward as independent variables, adding other variables related to socio-economic status and nurse workforce. To investigate whether 7:1 bed density made the largest contribution to the nurse density, compared to other bed densities, we estimated the standardized regression coefficients. There were 344 SMAs in the study period, of which 343 were used because of data availability. There were approximately 553,600 full time equivalent nurses working in inpatient wards in hospitals. The mean (standard deviation) of the full time equivalent nurse density was 426.4 (147.5) and for 7:1 bed density, the figures were 271.9 (185.9). The 7:1 bed density ranged from 0.0 to 1,295.5. After adjusting for the possible confounders, there were more hospital nurses in the areas with higher densities of 7:1 beds (standardized regression coefficient 0.62, 95% confidence interval 0.56-0.68). We found that the 7:1 nurse staffing standard made the largest contribution to the geographic distribution of hospital nurses, adjusted for socio-economic status and nurse workforce-related factors.

The retina of the shovel-nosed ray, Rhinobatos batillum (Rhinobatidae): morphology and quantitative analysis of the ganglion, amacrine and bipolar cell populations.

PubMed

Collin, S P

1988-01-01

A light microscopy study of the retina of the shovel-nosed ray, Rhinobatos batillum (Rhinobatidae) has revealed a duplex retina with a rod to cone ratio between 4:1 and 6:1. The inner nuclear layer consists of three layers of large horizontal cells, tightly packed, stellate bipolar cells, and up to three substrata of amacrine cells. The collaterals of the many supporting Müller cells project from the inner to the outer limiting membrane and divide the retina into many subunits. The cells of the ganglion cell layer are distributed into two layers, although a large proportion of ganglion cells are also displaced into the inner plexiform and inner nuclear layers. Topographic analysis of the cells in the ganglion cell layer, inner plexiform and inner nuclear layers reveals a number of regional specializations or "areae centrales". Ganglion cells were retrogradely-labelled with cobalt-lysine from the optic nerve, and three sub-populations of neurons characterized on their soma size and position. Small (20-50 microns2), large (80-300 microns2) and giant (greater than 300 microns2) sub-populations of ganglion cells each revealed distinct retinal specializations with peak densities of 3 x 10(3), 1.25 x 10(3) and 1.57 x 10(3) cells per mm2, respectively. Topographical comparison between Nissl-stained and retrogradely-labelled ganglion cell populations have established that a maximum of 20% in the "area centralis", and 75% in unspecialized, peripheral regions of the retina are non-ganglion cells. Out of a total of 210,566 cells in the ganglion cell layer, 49% were found to be non-ganglion cells. Iso-density contour maps of amacrine and bipolar cell distributions also reveal some specializations. These cell concentrations lie in corresponding regions to areas of increased density in the large and giant ganglion cell populations, suggesting some functional association.

Developing accurate survey methods for estimating population sizes and trends of the critically endangered Nihoa Millerbird and Nihoa Finch.

USGS Publications Warehouse

Gorresen, P. Marcos; Camp, Richard J.; Brinck, Kevin W.; Farmer, Chris

2012-01-01

Point-transect surveys indicated that millerbirds were more abundant than shown by the striptransect method, and were estimated at 802 birds in 2010 (95%CI = 652 – 964) and 704 birds in 2011 (95%CI = 579 – 837). Point-transect surveys yielded population estimates with improved precision which will permit trends to be detected in shorter time periods and with greater statistical power than is available from strip-transect survey methods. Mean finch population estimates and associated uncertainty were not markedly different among the three survey methods, but the performance of models used to estimate density and population size are expected to improve as the data from additional surveys are incorporated. Using the pointtransect survey, the mean finch population size was estimated at 2,917 birds in 2010 (95%CI = 2,037 – 3,965) and 2,461 birds in 2011 (95%CI = 1,682 – 3,348). Preliminary testing of the line-transect method in 2011 showed that it would not generate sufficient detections to effectively model bird density, and consequently, relatively precise population size estimates. Both species were fairly evenly distributed across Nihoa and appear to occur in all or nearly all available habitat. The time expended and area traversed by observers was similar among survey methods; however, point-transect surveys do not require that observers walk a straight transect line, thereby allowing them to avoid culturally or biologically sensitive areas and minimize the adverse effects of recurrent travel to any particular area. In general, pointtransect surveys detect more birds than strip-survey methods, thereby improving precision and resulting population size and trend estimation. The method is also better suited for the steep and uneven terrain of Nihoa

How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

PubMed

Paschoal, L R P; Andrade, D P; Darrigran, G

2015-01-01

Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in Neotropical lentic environments.

Evaluating perspectives for PRRS virus elimination from pig dense areas with a risk factor based herd index.

PubMed

Fahrion, A S; Beilage, E grosse; Nathues, H; Dürr, S; Doherr, M G

2014-06-01

Porcine reproductive and respiratory syndrome virus (PRRSV) is wide-spread in pig populations globally. In many regions of Europe with intensive pig production and high herd densities, the virus is endemic and can cause disease and production losses. This fuels discussion about the feasibility and sustainability of virus elimination from larger geographic regions. The implementation of a program aiming at virus elimination for areas with high pig density is unprecedented and its potential success is unknown. The objective of this work was to approach pig population data with a simple method that could support assessing the feasibility of a sustainable regional PRRSV elimination. Based on known risk factors such as pig herd structure and neighborhood conditions, an index characterizing individual herds' potential for endemic virus circulation and reinfection was designed. This index was subsequently used to compare data of all pig herds in two regions with different pig- and herd-densities in Lower Saxony (North-West Germany) where PRRSV is endemic. Distribution of the indexed herds was displayed using GIS. Clusters of high herd index densities forming potential risk hot spots were identified which could represent key target areas for surveillance and biosecurity measures under a control program aimed at virus elimination. In an additional step, for the study region with the higher pig density (2463 pigs/km(2) farmland), the potential distribution of PRRSV-free and non-free herds during the implementation of a national control program aiming at national virus elimination was modeled. Complex herd and trade network structures suggest that PRRSV elimination in regions with intensive pig farming like that of middle Europe would have to involve legal regulation and be accompanied by important trade and animal movement restrictions. The proposed methodology of risk index mapping could be adapted to areas varying in size, herd structure and density. Interpreted in the regional context, this could help to classify the density of risk and to accordingly target resources and measures for elimination. Copyright © 2014 Elsevier B.V. All rights reserved.

Environmental Assessment for Replacement of the Main Gate Facility at New Boston Air Force Station, New Hampshire

DTIC Science & Technology

2015-01-01

rural portions of the towns of New Boston, Amherst, and Mont Vernon. The area is primarily designated for low- density residential use (USAF 2001...quiet outdoor and residential areas (EPA 1974). For protection against hearing loss in the general population from non-impulsive noise, the EPA guideline...rural with interspersed forests and residential areas. Land cover on the station is consistent with the surrounding area, and much of the habitat

Environmental Assessment for Replacement of the Main Gate Facility at New Boston Air Force Station, New Hampshire

DTIC Science & Technology

2015-01-01

portions of the towns of New Boston, Amherst, and Mont Vernon. The area is primarily designated for low- density residential use (USAF 2001). Single...and residential areas (EPA 1974). For protection against hearing loss in the general population from non-impulsive noise, the EPA guideline...interspersed forests and residential areas. Land cover on the station is consistent with the surrounding area, and much of the habitat present on

Environmentally friendly tool to control mosquito populations without risk of insecticide resistance: the Lehmann’s funnel entry trap

PubMed Central

2013-01-01

Background Current malaria control strategies have cut down the malaria burden in many endemic areas, however the emergence and rapid spread of insecticide and drug resistance undermine the success of these efforts. There is growing concern that malaria eradication will not be achieved without the introduction of novel control tools. One approach that has been developed in the last few years is based on house screening to reduce indoor mosquito vector densities and consequently decrease malaria transmission. Here screening and trapping were combined in one tool to control mosquito populations. The trap does not require an insecticide or even an attractant, yet it effectively collects incoming resistant and susceptible mosquitoes and kills them. Results Performance of the funnel entry trap was tested in low and high malaria vector density areas. An overall reduction of 70 to 80% of mosquito density was seen in both. Species and molecular forms of Anopheles gambiae identification indicated no variation in the number of Anopheles arabiensis and the molecular forms of An. gambiae between houses and traps. Mosquitoes collected in the traps and in houses were highly resistant to pyrethroids (0.9 kdr-based mechanism). Conclusion There is a global consensus that new intervention tools are needed to cross the last miles in malaria elimination/eradication. The funnel entry trap showed excellent promise in suppressing mosquito densities even in area of high insecticide resistance. It requires no chemicals and is self-operated. PMID:23758904

Addressing population heterogeneity and distribution in epidemics models using a cellular automata approach

PubMed Central

2014-01-01

Background The spread of an infectious disease is determined by biological and social factors. Models based on cellular automata are adequate to describe such natural systems consisting of a massive collection of simple interacting objects. They characterize the time evolution of the global system as the emergent behaviour resulting from the interaction of the objects, whose behaviour is defined through a set of simple rules that encode the individual behaviour and the transmission dynamic. Methods An epidemic is characterized trough an individual–based–model built upon cellular automata. In the proposed model, each individual of the population is represented by a cell of the automata. This way of modeling an epidemic situation allows to individually define the characteristic of each individual, establish different scenarios and implement control strategies. Results A cellular automata model to study the time evolution of a heterogeneous populations through the various stages of disease was proposed, allowing the inclusion of individual heterogeneity, geographical characteristics and social factors that determine the dynamic of the desease. Different assumptions made to built the classical model were evaluated, leading to following results: i) for low contact rate (like in quarantine process or low density population areas) the number of infective individuals is lower than other areas where the contact rate is higher, and ii) for different initial spacial distributions of infected individuals different epidemic dynamics are obtained due to its influence on the transition rate and the reproductive ratio of disease. Conclusions The contact rate and spatial distributions have a central role in the spread of a disease. For low density populations the spread is very low and the number of infected individuals is lower than in highly populated areas. The spacial distribution of the population and the disease focus as well as the geographical characteristic of the area play a central role in the dynamics of the desease. PMID:24725804

Addressing population heterogeneity and distribution in epidemics models using a cellular automata approach.

PubMed

López, Leonardo; Burguerner, Germán; Giovanini, Leonardo

2014-04-12

The spread of an infectious disease is determined by biological and social factors. Models based on cellular automata are adequate to describe such natural systems consisting of a massive collection of simple interacting objects. They characterize the time evolution of the global system as the emergent behaviour resulting from the interaction of the objects, whose behaviour is defined through a set of simple rules that encode the individual behaviour and the transmission dynamic. An epidemic is characterized trough an individual-based-model built upon cellular automata. In the proposed model, each individual of the population is represented by a cell of the automata. This way of modeling an epidemic situation allows to individually define the characteristic of each individual, establish different scenarios and implement control strategies. A cellular automata model to study the time evolution of a heterogeneous populations through the various stages of disease was proposed, allowing the inclusion of individual heterogeneity, geographical characteristics and social factors that determine the dynamic of the desease. Different assumptions made to built the classical model were evaluated, leading to following results: i) for low contact rate (like in quarantine process or low density population areas) the number of infective individuals is lower than other areas where the contact rate is higher, and ii) for different initial spacial distributions of infected individuals different epidemic dynamics are obtained due to its influence on the transition rate and the reproductive ratio of disease. The contact rate and spatial distributions have a central role in the spread of a disease. For low density populations the spread is very low and the number of infected individuals is lower than in highly populated areas. The spacial distribution of the population and the disease focus as well as the geographical characteristic of the area play a central role in the dynamics of the desease.

Fishery-independent data reveal negative effect of human population density on Caribbean predatory fish communities.

PubMed

Stallings, Christopher D

2009-01-01

Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable.

Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities

PubMed Central

Stallings, Christopher D.

2009-01-01

Background Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. Methodology/Principal Findings Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. Conclusions/Significance Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable. PMID:19421312

Short communication: Methicillin-resistant Staphylococcus aureus in bulk tank milk of dairy cows and effect of swine population density.

PubMed

Locatelli, C; Cremonesi, P; Bertocchi, L; Zanoni, M G; Barberio, A; Drigo, I; Varisco, G; Castiglioni, B; Bronzo, V; Moroni, P

2016-03-01

The methicillin-resistant Staphylococcus aureus (MRSA) has recently frequently been reported in dairy cattle, usually with low prevalence. The livestock-associated MRSA (LA-MRSA) ST398 is especially involved in cases of subclinical and clinical mastitis. Swine carry LA-MRSA without clinical symptoms and are considered its reservoir and shedder. People exposed to swine are particularly at risk of LA-MRSA colonization. Environments with relevant livestock density are a demonstrated risk factor for humans to be carriers of a LA-MRSA. This work investigated dairy farms located in an area with a high livestock density, mainly represented by swine. Bulk tank milk samples from 224 dairy farms were collected, and their status was defined as MRSA-positive or MRSA-negative based on culture on chromogenic medium. The number of fattening swine and of fattening swine herds was calculated in an area of 3 km around each dairy farm through georeferencing. The probability of a Staphylococcus aureus-positive dairy farm to be MRSA positive based on the extent of potential infective pressure due to swine density was calculated. Both the number of swine herds and the number of swine were associated with the MRSA status of dairy herds. The 9 MRSA isolated were typed by multi-locus sequence typing and spa-typing, and characterized for their virulence factors and antimicrobial resistance profiles. The ST and spa-types detected are consistent with those present in the Italian swine population. Virulence and resistance profiles are mostly consistent with the types detected. This work provides the first evidence of the epidemiological challenge exerted by the density of the swine population on MRSA in dairy cows. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Sustainable Skyscrapers: Designing the Net Zero Energy Building of the Future

NASA Astrophysics Data System (ADS)

Kothari, S.; Bartsch, A.

2016-12-01

Cities of the future will need to increase population density in order to keep up with the rising populations in the limited available land area. In order to provide sufficient power as the population grows, cities must become more energy efficient. Fossil fuels and grid energy will continue to become more expensive as nonrenewable resources deplete. The obvious solution to increase population density while decreasing the reliance on fossil fuels is to build taller skyscrapers that are energy neutral, i.e. self-sustaining. However, current skyscrapers are not energy efficient, and therefore cannot provide a sustainable solution to the problem of increasing population density in the face of depleting energy resources. The design of a net zero energy building that includes both residential and commercial space is presented. Alternative energy systems such as wind turbines, photovoltaic cells, and a waste-to-fuel conversion plant have been incorporated into the design of a 50 story skyscraper that is not reliant on fossil fuels and has a payback time of about six years. Although the current building was designed to be located in San Francisco, simple modifications to the design would allow this building to fit the needs of any city around the world.

Assessment of the methodology for estimating ridge density in fingerprints and its forensic application.

PubMed

Gutiérrez-Redomero, Esperanza; Rivaldería, Noemí; Alonso-Rodríguez, Concepción; Sánchez-Andrés, Ángeles

2014-05-01

In recent times, some studies have explored the forensic application of dermatoglyphic traits such as the epidermal ridge breadth or ridge density (RD) toward the inference of sex and population from fingerprints of unknown origin, as it has been demonstrated that there exist significant differences of fingerprints between sexes and between populations. Part of the population differences found between these studies could be of methodological nature, due both to the lack of standardisation in the position of the counting area, as well as to the differences in the method used for obtaining the fingerprint. Therefore, the aim of this study was to check whether there are differences between the RD of fingerprints depending on where the counting area is placed and how the fingerprints are obtained. Fingerprints of each finger were obtained from 102 adult Spanish subjects (50 females and 52 males), using two methods (plain and rolled). The ridge density of each fingerprint was assessed in five different areas of the dactylogram: two closer to the core area (one on the radial and the other on the ulnar side), two closer to the outermost area of each of the sides (radial and ulnar), and another one in the proximal region of the fingertip. Regardless of the method used and of the position of the counting area, thumbs and forefingers show a higher RD than middle, ring, and little fingers in both sexes, and females present a higher RD than males in all areas and fingers. In both males and females, RD values on the core region are higher than those on the outer region, irrespective of the technique of fingerprinting used (rolled or plain). Regardless of the sex and location of the count area (core or outer), the rolled fingerprints exhibit RD greater than that of the plain ones in both radial and proximal areas, whereas the trend is inverted in the ulnar area, where rolled fingerprints demonstrate RD lesser than that of the plain ones. Therefore, in order for the results of different studies to be comparable, it is necessary to standardise the position of the count area and to use the same method of obtaining the fingerprint, especially when involving a forensic application. Copyright © 2013 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Using a Geolocation Social Networking Application to Calculate the Population Density of Sex-Seeking Gay Men for Research and Prevention Services

PubMed Central

Kramer, Michael R; Waller, Lance A; Flanders, W Dana; Sullivan, Patrick S

2014-01-01

Background In the United States, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) continues to have a heavy impact on men who have sex with men (MSM). Among MSM, black men under the age of 30 are at the most risk for being diagnosed with HIV. The US National HIV/AIDS strategy recommends intensifying efforts in communities that are most heavily impacted; to do so requires new methods for identifying and targeting prevention resources to young MSM, especially young MSM of color. Objective We piloted a methodology for using the geolocation features of social and sexual networking applications as a novel approach to calculating the local population density of sex-seeking MSM and to use self-reported age and race from profile postings to highlight areas with a high density of minority and young minority MSM in Atlanta, Georgia. Methods We collected data from a geographically systematic sample of points in Atlanta. We used a sexual network mobile phone app and collected application profile data, including age, race, and distance from each point, for either the 50 closest users or for all users within a 2-mile radius of sampled points. From these data, we developed estimates of the spatial density of application users in the entire city, stratified by race. We then compared the ratios and differences between the spatial densities of black and white users and developed an indicator of areas with the highest density of users of each race. Results We collected data from 2666 profiles at 79 sampled points covering 883 square miles; overlapping circles of data included the entire 132.4 square miles in Atlanta. Of the 2666 men whose profiles were observed, 1563 (58.63%) were white, 810 (30.38%) were black, 146 (5.48%) were another race, and 147 (5.51%) did not report a race in their profile. The mean age was 31.5 years, with 591 (22.17%) between the ages of 18-25, and 496 (18.60%) between the ages of 26-30. The mean spatial density of observed profiles was 33 per square mile, but the distribution of profiles observed across the 79 sampled points was highly skewed (median 17, range 1-208). Ratio, difference, and distribution outlier measures all provided similar information, highlighting areas with higher densities of minority and young minority MSM. Conclusions Using a limited number of sampled points, we developed a geospatial density map of MSM using a social-networking sex-seeking app. This approach provides a simple method to describe the density of specific MSM subpopulations (users of a particular app) for future HIV behavioral surveillance and allow targeting of prevention resources such as HIV testing to populations and areas of highest need. PMID:25406722

OGLE-ing the Magellanic system: stellar populations in the Magellanic Bridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skowron, D. M.; Jacyszyn, A. M.; Udalski, A.

We report the discovery of a young stellar bridge that forms a continuous connection between the Magellanic Clouds. This finding is based on number density maps for stellar populations found in data gathered by OGLE-IV that fully cover over 270 deg{sup 2} of the sky in the Magellanic Bridge area. This is the most extensive optical survey of this region to date. We find that the young population is present mainly in the western half of the MBR, which, together with the newly discovered young population in the eastern Bridge, form a continuous stream of stars connecting both galaxies alongmore » δ ∼ –73.5 deg. The young population distribution is clumped, with one of the major densities close to the SMC and the other fairly isolated and located approximately mid-way between the Clouds, which we call the OGLE island. These overdensities are well matched by H I surface density contours, although the newly found young population in the eastern Bridge is offset by ∼2 deg north from the highest H I density contour. We observe a continuity of red clump stars between the Magellanic Clouds which represent an intermediate-age population. Red clump stars are present mainly in the southern and central parts of the Magellanic Bridge, below its gaseous part, and their presence is reflected by a strong deviation from the radial density profiles of the two galaxies. This may indicate either a tidal stream of stars, or that the stellar halos of the two galaxies overlap. On the other hand, we do not observe such an overlap within an intermediate-age population represented by the top of the red giant branch and the asymptotic giant branch stars. We also see only minor mixing of the old populations of the Clouds in the southern part of the Bridge, represented by the lowest part of the red giant branch.« less

Multilevel Spatial Structure Impacts on the Pollination Services of Comarum palustre (Rosaceae)

PubMed Central

Somme, Laurent; Mayer, Carolin; Jacquemart, Anne-Laure

2014-01-01

Habitat destruction and fragmentation accelerate pollinator decline, consequently disrupting ecosystem processes such as pollination. To date, the impacts of multilevel spatial structure on pollination services have rarely been addressed. We focused on the effects of population spatial structure on the pollination services of Comarum palustre at three levels (i.e. within-population, between-populations and landscape). For three years, we investigated 14 Belgian populations, which differed in their within-population flower density, population surface, closure (i.e. proportion of the population edge that consisted of woody elements) and isolation (i.e. percentage of woody area cover within a 500 m radius from the population centre). We tested whether these spatial characteristics impact on pollinator abundance and visitation rate and thus, reproductive success of C. palustre. Insects were observed in 15 randomly-chosen plots in each population. We tested for pollen limitation with supplemental hand-cross pollination. Bumble bees and solitary bees were the major pollinators through all populations. Within populations, plots with high flower densities attracted high numbers of bumble bees and other insects. High bumble bee and solitary bee abundance was observed in populations presenting high proportions of woody edges and in populations within landscapes presenting high proportions of woody areas. Seed set resulting from open pollination varied with bumble bee and solitary bee visitation rate, leading to increased pollen limitation when pollinators were scarce. Since the reproductive success depended on the visitation rate of the main pollinators, which depended on multilevel spatial structure, wetland management plans should pay special attention to favour a mosaic of biotopes, including nesting sites and food resources for insects. This study particularly supports the relevance of a mix wetlands and woody habitats to bees. PMID:24915450

Multilevel spatial structure impacts on the pollination services of Comarum palustre (Rosaceae).

PubMed

Somme, Laurent; Mayer, Carolin; Jacquemart, Anne-Laure

2014-01-01

Habitat destruction and fragmentation accelerate pollinator decline, consequently disrupting ecosystem processes such as pollination. To date, the impacts of multilevel spatial structure on pollination services have rarely been addressed. We focused on the effects of population spatial structure on the pollination services of Comarum palustre at three levels (i.e. within-population, between-populations and landscape). For three years, we investigated 14 Belgian populations, which differed in their within-population flower density, population surface, closure (i.e. proportion of the population edge that consisted of woody elements) and isolation (i.e. percentage of woody area cover within a 500 m radius from the population centre). We tested whether these spatial characteristics impact on pollinator abundance and visitation rate and thus, reproductive success of C. palustre. Insects were observed in 15 randomly-chosen plots in each population. We tested for pollen limitation with supplemental hand-cross pollination. Bumble bees and solitary bees were the major pollinators through all populations. Within populations, plots with high flower densities attracted high numbers of bumble bees and other insects. High bumble bee and solitary bee abundance was observed in populations presenting high proportions of woody edges and in populations within landscapes presenting high proportions of woody areas. Seed set resulting from open pollination varied with bumble bee and solitary bee visitation rate, leading to increased pollen limitation when pollinators were scarce. Since the reproductive success depended on the visitation rate of the main pollinators, which depended on multilevel spatial structure, wetland management plans should pay special attention to favour a mosaic of biotopes, including nesting sites and food resources for insects. This study particularly supports the relevance of a mix wetlands and woody habitats to bees.

Consequences of severe habitat fragmentation on density, genetics, and spatial capture-recapture analysis of a small bear population.

PubMed

Murphy, Sean M; Augustine, Ben C; Ulrey, Wade A; Guthrie, Joseph M; Scheick, Brian K; McCown, J Walter; Cox, John J

2017-01-01

Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS) of Florida, USA, black bears (Ursus americanus floridanus) to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades. We conducted a noninvasive genetic spatial capture-recapture study to quantitatively describe the degree of contemporary habitat fragmentation and investigate the consequences of habitat fragmentation on population density and genetics of the HGS. Remaining natural habitats sustaining the HGS were significantly more fragmented and patchier than those supporting Florida's largest black bear subpopulation. Genetic diversity was low (AR = 3.57; HE = 0.49) and effective population size was small (NE = 25 bears), both of which remained unchanged over a period spanning one bear generation despite evidence of some immigration. Subpopulation density (0.054 bear/km2) was among the lowest reported for black bears, was significantly female-biased, and corresponded to a subpopulation size of 98 bears in available habitat. Conserving remaining natural habitats in the area occupied by the small, genetically depauperate HGS, possibly through conservation easements and government land acquisition, is likely the most important immediate step to ensuring continued persistence of bears in this area. Our study also provides evidence that preferentially placing detectors (e.g., hair traps or cameras) primarily in quality habitat across fragmented landscapes poses a challenge to estimating density-habitat covariate relationships using spatial capture-recapture models. Because habitat fragmentation and loss are likely to increase in severity globally, further investigation of the influence of habitat fragmentation and detector placement on estimation of this relationship is warranted.

Consequences of severe habitat fragmentation on density, genetics, and spatial capture-recapture analysis of a small bear population

PubMed Central

Guthrie, Joseph M.; Scheick, Brian K.; McCown, J. Walter; Cox, John J.

2017-01-01

Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS) of Florida, USA, black bears (Ursus americanus floridanus) to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades. We conducted a noninvasive genetic spatial capture-recapture study to quantitatively describe the degree of contemporary habitat fragmentation and investigate the consequences of habitat fragmentation on population density and genetics of the HGS. Remaining natural habitats sustaining the HGS were significantly more fragmented and patchier than those supporting Florida’s largest black bear subpopulation. Genetic diversity was low (AR = 3.57; HE = 0.49) and effective population size was small (NE = 25 bears), both of which remained unchanged over a period spanning one bear generation despite evidence of some immigration. Subpopulation density (0.054 bear/km2) was among the lowest reported for black bears, was significantly female-biased, and corresponded to a subpopulation size of 98 bears in available habitat. Conserving remaining natural habitats in the area occupied by the small, genetically depauperate HGS, possibly through conservation easements and government land acquisition, is likely the most important immediate step to ensuring continued persistence of bears in this area. Our study also provides evidence that preferentially placing detectors (e.g., hair traps or cameras) primarily in quality habitat across fragmented landscapes poses a challenge to estimating density-habitat covariate relationships using spatial capture-recapture models. Because habitat fragmentation and loss are likely to increase in severity globally, further investigation of the influence of habitat fragmentation and detector placement on estimation of this relationship is warranted. PMID:28738077

The frequency and distribution of recent landslides in three montane tropical regions of Puerto Rico

USGS Publications Warehouse

Larsen, M.C.; Torres-Sanchez, A. J.

1998-01-01

Landslides are common in sttep mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high. Each year, landslides cause extensive damage to property and coccasionally result in loss of life. Average population density is high, 422 people/km2, and is increasing. This increase in population density is accompanied by growing stress on the natural environment and physical infrastructure. As a result, human populations are more vulnerable to landslide hazards. The Blanco, Cibuco, and Coamo study areas range in surface area from 276 to 350 km2 and represent the climatologic, geographic, and geologic conditions that typify Puerto Rico. Maps of recent landslides developed from 1:20 000-scale aerial photographs, in combination with a computerized geographic information system, were used to evaluate the frequency and distribution of shallow landslides in these areas. Several types of landslides were documented-rainfall-triggered debris flows, shallow soil slips, and slumps were most abundant. Hillslopes in the study area that have been anthropogenically modified, exceed 12?? in gradient, and greater than 300 m in elevation, and face the east-northeast, are most prone to landsliding. A set of simplified matrices representing geographic conditions in the three study areas was developed and provides a basis for the estimation of the spatial controls on the frequency of landslides in Puerto Rico. this approach is an example of an analysis of the frequency of landslides that is computationally simple,. and therefore, may be easily transferable to other settings.

Large herbivores affect forest ecosystem functions by altering the structure of dung beetle communities

NASA Astrophysics Data System (ADS)

Iida, Taichi; Soga, Masashi; Koike, Shinsuke

2018-04-01

Dramatic increases in populations of large mammalian herbivores have become a major ecological issue, particularly in the northern hemisphere, due to their substantial impacts on both animal and plant communities through processes such as grazing, browsing, and trampling. However, little is known about the consequences of these population explosions on ecosystem functions. Here, we experimentally investigated how the population density of sika deer (Cervus nippon) in temperate deciduous forest areas in Japan affected the decomposition of mammal dung by dung beetles, which is a key process in forest ecosystems. We measured a range of environmental variables (e.g., vegetation cover, soil hardness) and the dung decomposition rate, measured as the amount of deer dung decomposed during one week, and sampled dung beetles at 16 study sites with three different deer densities (high/intermediate/low). We then used structural equation modeling to investigate the relationships between deer density, environmental variables, the biomass of dung beetles (classified into small or large species), and the dung decomposition rate. We found that the biomass of small species increased with increasing deer density, whereas that of large species was not related to deer density. Furthermore, the dung decomposition rate was positively related to the biomass of small species but unrelated to that of large species. Overall, our results showed that an increase in deer density affects the decomposition rate of mammal dung by changing the structure of dung beetle communities (i.e., increasing the number of small dung beetles). Such an understanding of how increases in large herbivore populations affect ecosystem functions is important for accurately evaluating the ecological consequences of their overabundance and ultimately managing their populations appropriately.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults.

PubMed

Loi, Barbara; Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m 2 ). The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults

PubMed Central

Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

Background In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Methods Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m2). Results The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Discussion Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply. PMID:28289567

Increased tornado hazard in large metropolitan areas

NASA Astrophysics Data System (ADS)

Cusack, Stephen

2014-11-01

The tornado climate was compared between large metropolitan areas and neighbouring non-metro cities using modern tornado reports in the Storm Prediction Center (SPC) archives. Twenty large metro areas in the higher-risk region of the U.S. were used to boost sample sizes hence robustness of results. Observational biases were minimised by using the most densely populated zips. The analysis found 50% greater tornado frequency and a thicker-tailed severity distribution in metro areas compared to the non-metro cities. These differences are significant at the 1% level. Regarding tornado frequency, the primary question is whether the raised occurrence rates in metro areas are due to observation biases or real differences in tornado climate. Past studies found no relative biases at the population densities used here, whereas there are two potential urban drivers of tornadogenesis. First, the urban heat island raises the storm severity above and downwind of main urban areas, as recorded in precipitation and lightning datasets. Second, the increased surface roughness over metro areas raises low-level shear which in turn has been found to be favourable for tornadogenesis. Modification of convective storms over large metro areas is the more plausible explanation of raised tornado frequency. The drivers of a thicker-tailed tornado severity distribution in metro areas are less certain. Potential causes include: increased debris-loading in metro tornadoes; modification of storms' lower boundary layer by increased surface roughness in metro areas; the reduced density of damage indicators in non-metro cities.

The Potential for Spatial Distribution Indices to Signal Thresholds in Marine Fish Biomass

PubMed Central

Reuchlin-Hugenholtz, Emilie

2015-01-01

The frequently observed positive relationship between fish population abundance and spatial distribution suggests that changes in distribution can be indicative of trends in abundance. If contractions in spatial distribution precede declines in spawning stock biomass (SSB), spatial distribution reference points could complement the SSB reference points that are commonly used in marine conservation biology and fisheries management. When relevant spatial distribution information is integrated into fisheries management and recovery plans, risks and uncertainties associated with a plan based solely on the SSB criterion would be reduced. To assess the added value of spatial distribution data, we examine the relationship between SSB and four metrics of spatial distribution intended to reflect changes in population range, concentration, and density for 10 demersal populations (9 species) inhabiting the Scotian Shelf, Northwest Atlantic. Our primary purpose is to assess their potential to serve as indices of SSB, using fisheries independent survey data. We find that metrics of density offer the best correlate of spawner biomass. A decline in the frequency of encountering high density areas is associated with, and in a few cases preceded by, rapid declines in SSB in 6 of 10 populations. Density-based indices have considerable potential to serve both as an indicator of SSB and as spatially based reference points in fisheries management. PMID:25789624

Ecological distribution and crude density of breeding birds on prairie wetlands

USGS Publications Warehouse

Kantrud, H.A.; Stewart, R.E.

1984-01-01

Breeding populations of 28 species of wetland-dwelling birds other than waterfowl (Anatidae) were censused on 1,321 wetlands lying within the prairie pothole region of North Dakota. Ecological distribution and two crude measures of relative density were calculated for the 22 commonest species using eight wetland classes. Semipermanent wetlands supported nearly two-thirds of the population and were used by all 22 species, whereas seasonal wetlands contained about one-third of the population and were used by 20 species Semipermanent, fen, and temporary wetlands contained highest bird densities on the basis of wetland area; on the basis of wetland unit, densities were highest on semipermanent, permanent, alkali, and fen wetlands. The highest ranking of semipermanent wetlands by all three measures of use was probably because these wetlands, as well as being relatively numerous and large, were vegetatively diverse. The fairly large proportion of the bird population supported by seasonal wetlands was a result of wetland abundance and moderate vegetative diversity. Increased vegetative diversity results from the development of characteristic zones of hydrophytes at sites where water persists longer during the growing season. Frequent cultivation of prairie wetlands results in the replacement of tall, robust perennials by bare soil or stands of short, weak-stemmed annuals that likely are unattractive to nesting birds.

Mark-recapture using tetracycline and genetics reveal record-high bear density

USGS Publications Warehouse

Peacock, E.; Titus, K.; Garshelis, D.L.; Peacock, M.M.; Kuc, M.

2011-01-01

We used tetracycline biomarking, augmented with genetic methods to estimate the size of an American black bear (Ursus americanus) population on an island in Southeast Alaska. We marked 132 and 189 bears that consumed remote, tetracycline-laced baits in 2 different years, respectively, and observed 39 marks in 692 bone samples subsequently collected from hunters. We genetically analyzed hair samples from bait sites to determine the sex of marked bears, facilitating derivation of sex-specific population estimates. We obtained harvest samples from beyond the study area to correct for emigration. We estimated a density of 155 independent bears/100 km2, which is equivalent to the highest recorded for this species. This high density appears to be maintained by abundant, accessible natural food. Our population estimate (approx. 1,000 bears) could be used as a baseline and to set hunting quotas. The refined biomarking method for abundance estimation is a useful alternative where physical captures or DNA-based estimates are precluded by cost or logistics. Copyright ?? 2011 The Wildlife Society.

Risk factors associated with typhoid fever in children aged 2-16 years in Karachi, Pakistan.

PubMed

Khan, M I; Ochiai, R L; Soofi, S B; Von-Seidlein, L; Khan, M J; Sahito, S M; Habib, M A; Puri, M K; Park, J K; You, Y A; Ali, M; Nizami, S Q; Acosta, C J; Bradley-Sack, R; Clemens, J D; Bhutta, Z A

2012-04-01

We analysed the data from the control group in a typhoid vaccine trial in Karachi to assess the differences in individual-, household- and cluster-level characteristics for developing typhoid fever. The annual incidence of typhoid in children aged 2-16 years in the control arm of the vaccine trial was 151/100 000 population. After adjustment, the risk of typhoid was lower with increasing age [risk ratio (RR) 0·89, 95% confidence interval (CI) 0·83-0·95], was higher with an increase in population density (RR 1·13, 95% CI 1·05-1·21) and was lower in the households using a safe drinking-water source (RR 0·63, 95% CI 0·41-0·99). Typhoid fever affects younger children living in areas of high population density and lack of access to safe water in Pakistan. A combination of environmental and biological interventions is required to prevent the continued epidemiological and economic impact of typhoid fever in high-risk areas of Pakistan.

Expression of the transcription factor FOXP2 in brainstem respiratory circuits of adult rat is restricted to upper-airway pre-motor areas.

PubMed

Stanić, Davor; Dhingra, Rishi R; Dutschmann, Mathias

2018-04-01

Expression of the transcription factor FOXP2 is linked to brain circuits that control motor function and speech. Investigation of FOXP2 protein expression in respiratory areas of the ponto-medullary brainstem of adult rat revealed distinct rostro-caudal expression gradients. A high density of FOXP2 immunoreactive nuclei was observed within the rostral pontine Kölliker-Fuse nucleus, compared to low densities in caudal pontine and rostral medullary respiratory nuclei, including the: (i) noradrenergic A5 and parafacial respiratory groups; (ii) Bötzinger and pre-Bötzinger complex and; (iii) rostral ventral respiratory group. Moderate densities of FOXP2 immunoreactive nuclei were observed in the caudal ventral respiratory group and the nucleus retroambiguus, with significant density levels found in the caudal half of the dorsal respiratory group and the hypoglossal pre-motor area lateral around calamus scriptorius. FOXP2 immunoreactivity was absent in all cranial nerve motor nuclei. We conclude that FOXP2 expression in respiratory brainstem areas selectively delineates laryngeal and hypoglossal pre-motor neuron populations essential for the generation of sound and voice. Copyright © 2018 Elsevier B.V. All rights reserved.

Small-mammal density estimation: A field comparison of grid-based vs. web-based density estimators

USGS Publications Warehouse

Parmenter, R.R.; Yates, Terry L.; Anderson, D.R.; Burnham, K.P.; Dunnum, J.L.; Franklin, A.B.; Friggens, M.T.; Lubow, B.C.; Miller, M.; Olson, G.S.; Parmenter, Cheryl A.; Pollard, J.; Rexstad, E.; Shenk, T.M.; Stanley, T.R.; White, Gary C.

2003-01-01

Statistical models for estimating absolute densities of field populations of animals have been widely used over the last century in both scientific studies and wildlife management programs. To date, two general classes of density estimation models have been developed: models that use data sets from capture–recapture or removal sampling techniques (often derived from trapping grids) from which separate estimates of population size (NÌ‚) and effective sampling area (AÌ‚) are used to calculate density (DÌ‚ = NÌ‚/AÌ‚); and models applicable to sampling regimes using distance-sampling theory (typically transect lines or trapping webs) to estimate detection functions and densities directly from the distance data. However, few studies have evaluated these respective models for accuracy, precision, and bias on known field populations, and no studies have been conducted that compare the two approaches under controlled field conditions. In this study, we evaluated both classes of density estimators on known densities of enclosed rodent populations. Test data sets (n = 11) were developed using nine rodent species from capture–recapture live-trapping on both trapping grids and trapping webs in four replicate 4.2-ha enclosures on the Sevilleta National Wildlife Refuge in central New Mexico, USA. Additional “saturation” trapping efforts resulted in an enumeration of the rodent populations in each enclosure, allowing the computation of true densities. Density estimates (DÌ‚) were calculated using program CAPTURE for the grid data sets and program DISTANCE for the web data sets, and these results were compared to the known true densities (D) to evaluate each model's relative mean square error, accuracy, precision, and bias. In addition, we evaluated a variety of approaches to each data set's analysis by having a group of independent expert analysts calculate their best density estimates without a priori knowledge of the true densities; this “blind” test allowed us to evaluate the influence of expertise and experience in calculating density estimates in comparison to simply using default values in programs CAPTURE and DISTANCE. While the rodent sample sizes were considerably smaller than the recommended minimum for good model results, we found that several models performed well empirically, including the web-based uniform and half-normal models in program DISTANCE, and the grid-based models Mb and Mbh in program CAPTURE (with AÌ‚ adjusted by species-specific full mean maximum distance moved (MMDM) values). These models produced accurate DÌ‚ values (with 95% confidence intervals that included the true D values) and exhibited acceptable bias but poor precision. However, in linear regression analyses comparing each model's DÌ‚ values to the true D values over the range of observed test densities, only the web-based uniform model exhibited a regression slope near 1.0; all other models showed substantial slope deviations, indicating biased estimates at higher or lower density values. In addition, the grid-based DÌ‚ analyses using full MMDM values for WÌ‚ area adjustments required a number of theoretical assumptions of uncertain validity, and we therefore viewed their empirical successes with caution. Finally, density estimates from the independent analysts were highly variable, but estimates from web-based approaches had smaller mean square errors and better achieved confidence-interval coverage of D than did grid-based approaches. Our results support the contention that web-based approaches for density estimation of small-mammal populations are both theoretically and empirically superior to grid-based approaches, even when sample size is far less than often recommended. In view of the increasing need for standardized environmental measures for comparisons among ecosystems and through time, analytical models based on distance sampling appear to offer accurate density estimation approaches for research studies involving small-mammal abundances.

Presence and distribution of chlorinated organic compounds in streambed sediments, new jersey

USGS Publications Warehouse

Stackelberg, P.E.

1997-01-01

Concentrations of 18 hydrophobic chlorinated organic compounds in streambed sediments from 100 sites throughout New Jersey were examined to determine (1) which compounds were detected most frequently, (2) whether detection frequencies differed among selected drainage basins, and (3) whether concentrations differed significantly among selected drainage basins. Twelve drainage basins across New Jersey that contain a range of land-use patterns and population densities were selected to represent various types and degrees of development. To ensure an adequate number of samples for statistical comparison among drainage basins, the 12 selected basins were consolidated into seven drainage areas on the basis of similarities in land- use patterns and population densities. Additionally, data for three classes of chlorinated organic compounds in streambed sediments from 255 sites throughout New Jersey were examined to determine whether the presence of these compounds in streambed sediments is related to the type and degree of development within the drainage area of each sampling site. Chlorinated organic compounds detected most frequently within the seven representative drainage areas were DDT, DDE, DDD, chlordane, dieldrin, and PCBs. DDT, DDE, and DDD, which were the most widely distributed organic compounds, were detected in about 60 to 100 percent of the samples from all drainage areas hut one (where the detection rate for these compounds was about 20 to 40 percent). Chlordane and dieldrin were detected in about 80 to 100 percent of samples from highly urbanized and populated drainage areas; detection frequencies for these compounds tended to be smaller in less developed and populated areas. PCBs were detected in about 40 to 85 percent of samples from all drainage areas; detection frequencies were highest in the most heavily developed and populated areas. Analysis of variance on rank-transformed organic compound concentrations normalized to sediment organic carbon content was used to evaluate differences in concentrations among the seven representative drainage areas. Chlordane and PCBs were the chlorinated organic compounds with the most highly elevated concentrations in streambed sediments across the State. Median normalized COncentrations of all six of the most frequently detected chlorinated organic compounds were highest in the most heavily urbanized and populated drainage area and lowest in the less populated, predominantly agricultural or forested areas. Concentrations of DDT and DDE, however, did not differ significantly among most of the drainage areas. Concentrations of DDD, chlordane, dieldrin, and PCBs differed significantly among drainage areas. The highest median normalized concentrations were found in samples from the most heavily urbanized and populated areas, and the lowest were in samples from the least developed, most heavily forested area. Logistic regression was used to examine relations between the presence of hydrophobic chlorinated organic compounds in streambed sediments at specified concentrations and variables that characterize the type and degree of development within the drainage areas of 255 sites across New Jersey. The explanatory variables found most useful for predicting the presence of chlorinated organic compounds in streambed sediments include total population and amounts (in square kilometers) of various land-use categories. Logistic regression equations were developed to identify significant relations between population and amounts of specific land-use categories within drainage areas and the probability of detecting chlorinated organic contaminants in streambed sediments. These relations can be used to assist in the identification of geographic regions of primary concern for contamination of bed sediments by chlorinated organic compounds across the State.

Spatial patterns of distribution, abundance, and species diversity of small odontocetes estimated using density surface modeling with line transect sampling

NASA Astrophysics Data System (ADS)

Kanaji, Yu; Okazaki, Makoto; Miyashita, Tomio

2017-06-01

Spatial patterns of distribution, abundance, and species diversity of small odontocetes including species in the Delphinidae and Phocoenidae families were investigated using long-term dedicated sighting survey data collected between 1983 and 2006 in the North Pacific. Species diversity indices were calculated from abundance estimated using density surface modeling of line-transect data. The estimated abundance ranged from 19,521 individuals in killer whale to 1,886,022 in pantropical spotted dolphin. The predicted density maps showed that the habitats of small odontocetes corresponded well with distinct oceanic domains. Species richness was estimated to be highest between 30 and 40°N where warm- and cold-water currents converge. Simpson's Diversity Index showed latitudinal diversity gradients of decreasing species numbers toward the poles. Higher diversity was also estimated in the coastal areas and the zonal areas around 35-42°N. Coastal-offshore gradients and latitudinal gradients are known for many taxa. The zonal areas around 35°N and 40°N coincide with the Kuroshio Current and its extension and the subarctic boundary, respectively. These results suggest that the species diversity of small odontocetes primarily follows general patterns of latitudinal and longitudinal gradients, while the confluence of faunas originating in distinct water masses increases species diversify in frontal waters around 30-40°N. Population densities tended to be higher for the species inhabiting higher latitudes, but were highest for intermediate latitudes at approximately 35-40°N. According to latitudinal gradients in water temperature and biological productivity, the costs for thermoregulation will decrease in warmer low latitudes, while feeding efficiency will increase in colder high latitudes. These trade-offs could optimize population density in intermediate latitudes.

The Relationship Between Geographic Access to Plastic Surgeons and Breast Reconstruction Rates Among Women Undergoing Mastectomy for Cancer.

PubMed

Bauder, Andrew R; Gross, Cary P; Killelea, Brigid K; Butler, Paris D; Kovach, Stephen J; Fox, Justin P

2017-03-01

Despite a national health care policy requiring payers to cover breast reconstruction, rates of postmastectomy reconstruction are low, particularly among minority populations. We conducted this study to determine if geographic access to a plastic surgeon impacts breast reconstruction rates. Using 2010 inpatient and ambulatory surgery data from 10 states, we identified adult women who underwent mastectomy for breast cancer. Data were aggregated to the health service area (HSA) level and hierarchical generalized linear models were used to risk-standardize breast reconstruction rates (RSRR) across HSAs. The relationship between an HSA's RSRR and plastic surgeon density (surgeons/100,000 population) was quantified using correlation coefficients. The final cohort included 22,997 patients across 134 HSAs. There was substantial variation in plastic surgeon density (median, 1.4 surgeons/100,000; interquartile range, [0.0-2.6]/100,000) and the use of breast reconstruction (median RSRR, 43.0%; interquartile range, [29.9%-62.8%]) across HSAs. Higher plastic surgeon density was positively correlated with breast reconstruction rates (correlation coefficient = 0.66, P < 0.001) and inversely related to time between mastectomy and reconstruction (correlation coefficient = -0.19, P < 0.001). Non-white and publicly insured women were least likely to undergo breast reconstruction overall. Among privately insured patients, racial disparities were noted in high surgeon density areas (white = 79.0% vs. non-white = 63.3%; P < 0.001) but not in low surgeon density areas (34.4% vs 36.5%; P = 0.70). The lack of geographic access to a plastic surgeon serves as a barrier to breast reconstruction and may compound disparities in care associated with race and insurance status. Future efforts to improve equitable access should consider strategies to ensure access to appropriate clinical expertise.

Spatially varying density dependence drives a shifting mosaic of survival in a recovering apex predator (Canis lupus).

PubMed

O'Neil, Shawn T; Bump, Joseph K; Beyer, Dean E

2017-11-01

Understanding landscape patterns in mortality risk is crucial for promoting recovery of threatened and endangered species. Humans affect mortality risk in large carnivores such as wolves ( Canis lupus ), but spatiotemporally varying density dependence can significantly influence the landscape of survival. This potentially occurs when density varies spatially and risk is unevenly distributed. We quantified spatiotemporal sources of variation in survival rates of gray wolves ( C. lupus ) during a 21-year period of population recovery in the Upper Peninsula of Michigan, USA. We focused on mapping risk across time using Cox Proportional Hazards (CPH) models with time-dependent covariates, thus exploring a shifting mosaic of survival. Extended CPH models and time-dependent covariates revealed influences of seasonality, density dependence and experience, as well as individual-level factors and landscape predictors of risk. We used results to predict the shifting landscape of risk at the beginning, middle, and end of the wolf recovery time series. Survival rates varied spatially and declined over time. Long-term change was density-dependent, with landscape predictors such as agricultural land cover and edge densities contributing negatively to survival. Survival also varied seasonally and depended on individual experience, sex, and resident versus transient status. The shifting landscape of survival suggested that increasing density contributed to greater potential for human conflict and wolf mortality risk. Long-term spatial variation in key population vital rates is largely unquantified in many threatened, endangered, and recovering species. Variation in risk may indicate potential for source-sink population dynamics, especially where individuals preemptively occupy suitable territories, which forces new individuals into riskier habitat types as density increases. We encourage managers to explore relationships between adult survival and localized changes in population density. Density-dependent risk maps can identify increasing conflict areas or potential habitat sinks which may persist due to high recruitment in adjacent habitats.

Fish community changes in the St. Louis River estuary, Lake Superior, 1989-1996: Is it ruffe or population dynamics?

USGS Publications Warehouse

Bronte, Charles R.; Evrard, Lori M.; Brown, William P.; Mayo, Kathleen R.; Edwards, Andrew J.

1998-01-01

Ruffe (Gymnocephalus cernuus) have been implicated in density declines of native species through egg predation and competition for food in some European waters where they were introduced. Density estimates for ruffe and principal native fishes in the St. Louis River estuary (western Lake Superior) were developed for 1989 to 1996 to measure changes in the fish community in response to an unintentional introduction of ruffe. During the study, ruffe density increased and the densities of several native species decreased. The reductions of native stocks to the natural population dynamics of the same species from Chequamegon Bay, Lake Superior (an area with very few ruffe) were developed, where there was a 24-year record of density. Using these data, short- and long-term variations in catch and correlations among species within years were compared, and species-specific distributions were developed of observed trends in abundance of native fishes in Chequamegon Bay indexed by the slopes of densities across years. From these distributions and our observed trend-line slopes from the St. Louis River, probabilities of measuring negative change at the magnitude observed in the St. Louis River were estimated. Compared with trends in Chequamegon Bay, there was a high probability of obtaining the negative slopes measured for most species, which suggests natural population dynamics could explain, the declines rather than interactions with ruffe. Variable recruitment, which was not related to ruffe density, and associated density-dependent changes in mortality likely were responsible for density declines of native species.

Importance of the national petroleum reserve-alaska for aquatic birds.

PubMed

Bart, Jonathan; Platte, Robert M; Andres, Brad; Brown, Stephen; Johnson, James A; Larned, William

2013-12-01

We used data from aerial surveys (1992-2010) of >100,000 km(2) and ground surveys (1998-2004) of >150 km(2) to estimate the density and abundance of birds on the North Slope of Alaska (U.S.A.). In the ground surveys, we used double sampling to estimate detection ratios. We used the aerial survey data to compare densities of birds and Arctic fox (Vulpes lagopus), the major nest predator of birds, on the North Slope, in Prudhoe Bay, and in nearby areas. We partitioned the Prudhoe Bay oil field into 2 × 2 km plots and determined the relation between density of aquatic birds and density of roads, buildings, and other infrastructure in these plots. Abundance and density (birds per square kilometer) of 3 groups of aquatic birds-waterfowl, loons, and grebes; shorebirds; and gulls, terns, and jaegers-were highest in the National Petroleum Reserve-Alaska (NPRA) and lowest in the Arctic National Wildlife Refuge. Six other major wetlands occur in the Arctic regions of Canada and Russia, but the largest population of aquatic birds was in the NPRA. Aquatic birds were concentrated in the northern part of the NPRA. For example, an area that covered 18% of the NPRA included 53% of its aquatic birds. The aerial surveys showed that bird density was not lower and fox density was not higher in Prudhoe Bay than in surrounding areas. Density of infrastructure did not significantly affect bird density for any group of species. Our results establish that the NPRA is one of the most important areas for aquatic birds in the Arctic. Our results and those of others also indicate that oil production, as practiced in Prudhoe Bay, does not necessarily lead to substantial declines in bird density or productivity in or near the developed areas. Prioridades para la Conservación de Aves en el Norte de Alaska. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Spatiotemporal patterns of duck nest density and predation risk: a multi-scale analysis of 18 years and more than 10,000 nests

USGS Publications Warehouse

Ringelman, Kevin M.; Eadie, John M.; Ackerman, Joshua T.; Sih, Andrew; Loughman, Daniel L.; Yarris, Gregory S.; Oldenburger, Shaun L.; McLandress, M. Robert

2017-01-01

Many avian species are behaviorally-plastic in selecting nest sites, and may shift to new locations or habitats following an unsuccessful breeding attempt. If there is predictable spatial variation in predation risk, the process of many individuals using prior experience to adaptively change nest sites may scale up to create shifting patterns of nest density at a population level. We used 18 years of waterfowl nesting data to assess whether there were areas of consistently high or low predation risk, and whether low-risk areas increased, and high-risk areas decreased in nest density the following year. We created kernel density maps of successful and unsuccessful nests in consecutive years and found no correlation in predation risk and no evidence for adaptive shifts, although nest density was correlated between years. We also examined between-year correlations in nest density and nest success at three smaller spatial scales: individual nesting fields (10–28 ha), 16-ha grid cells and 4-ha grid cells. Here, results were similar across all scales: we found no evidence for year-to-year correlation in nest success but found strong evidence that nest density was correlated between years, and areas of high nest success increased in nest density the following year. Prior research in this system has demonstrated that areas of high nest density have higher nest success, and taken together, our results suggest that ducks may adaptively select nest sites based on the local density of conspecifics, rather than the physical location of last year's nest. In unpredictable environments, current cues, such as the presence of active conspecific nests, may be especially useful in selecting nest sites. The cues birds use to select breeding locations and successfully avoid predators deserve continued attention, especially in systems of conservation concern.

White-tailed deer harvest from the chronic wasting disease eradication zone in south-central Wisconsin

USGS Publications Warehouse

Blanchong, Julie A.; Joly, D.O.; Samuel, M.D.; Langenberg, J.A.; Rolley, R.E.; Sausen, J.F.

2006-01-01

Chronic wasting disease (CWD) was discovered in free-ranging white-tailed deer (Odocoileus virginianus) in south-central Wisconsin in 2002. The current control method for CWD in the state is the harvest of deer from affected areas to reduce population density and lower CWD transmission. We used spatial regression methods to identify factors associated with deer harvest across south-central Wisconsin. Harvest of deer by hunters was positively related to deer density (slope=0.003, 95% CI=0.0001-0.006), the number of landowners that requested harvest permits (slope=0.071, 95% CI=0.037-0.105), and proximity to the area of highest CWD infection (slope=-0.041, 95% CI=-0.056- -0.027). Concomitantly, harvest was not impacted in areas where landowners signed a petition protesting intensive deer reduction (slope=-0.00006, 95% CI=-0.0005-0.0003). Our results suggest that the success of programs designed to reduce deer populations for disease control or to reduce overabundance in Wisconsin are dependent on landowner and hunter participation. We recommend that programs or actions implemented to eradicate or mitigate the spread of CWD should monitor and assess deer population reduction and evaluate factors affecting program success to improve methods to meet management goals.

Detecting black bear source–sink dynamics using individual-based genetic graphs

PubMed Central

Draheim, Hope M.; Moore, Jennifer A.; Etter, Dwayne; Winterstein, Scott R.; Scribner, Kim T.

2016-01-01

Source–sink dynamics affects population connectivity, spatial genetic structure and population viability for many species. We introduce a novel approach that uses individual-based genetic graphs to identify source–sink areas within a continuously distributed population of black bears (Ursus americanus) in the northern lower peninsula (NLP) of Michigan, USA. Black bear harvest samples (n = 569, from 2002, 2006 and 2010) were genotyped at 12 microsatellite loci and locations were compared across years to identify areas of consistent occupancy over time. We compared graph metrics estimated for a genetic model with metrics from 10 ecological models to identify ecological factors that were associated with sources and sinks. We identified 62 source nodes, 16 of which represent important source areas (net flux > 0.7) and 79 sink nodes. Source strength was significantly correlated with bear local harvest density (a proxy for bear density) and habitat suitability. Additionally, resampling simulations showed our approach is robust to potential sampling bias from uneven sample dispersion. Findings demonstrate black bears in the NLP exhibit asymmetric gene flow, and individual-based genetic graphs can characterize source–sink dynamics in continuously distributed species in the absence of discrete habitat patches. Our findings warrant consideration of undetected source–sink dynamics and their implications on harvest management of game species. PMID:27440668

Unveiling relationships between crime and property in England and Wales via density scale-adjusted metrics and network tools.

PubMed

Ribeiro, Haroldo V; Hanley, Quentin S; Lewis, Dan

2018-01-01

Scale-adjusted metrics (SAMs) are a significant achievement of the urban scaling hypothesis. SAMs remove the inherent biases of per capita measures computed in the absence of isometric allometries. However, this approach is limited to urban areas, while a large portion of the world's population still lives outside cities and rural areas dominate land use worldwide. Here, we extend the concept of SAMs to population density scale-adjusted metrics (DSAMs) to reveal relationships among different types of crime and property metrics. Our approach allows all human environments to be considered, avoids problems in the definition of urban areas, and accounts for the heterogeneity of population distributions within urban regions. By combining DSAMs, cross-correlation, and complex network analysis, we find that crime and property types have intricate and hierarchically organized relationships leading to some striking conclusions. Drugs and burglary had uncorrelated DSAMs and, to the extent property transaction values are indicators of affluence, twelve out of fourteen crime metrics showed no evidence of specifically targeting affluence. Burglary and robbery were the most connected in our network analysis and the modular structures suggest an alternative to "zero-tolerance" policies by unveiling the crime and/or property types most likely to affect each other.

Unveiling relationships between crime and property in England and Wales via density scale-adjusted metrics and network tools

PubMed Central

Hanley, Quentin S.; Lewis, Dan

2018-01-01

Scale-adjusted metrics (SAMs) are a significant achievement of the urban scaling hypothesis. SAMs remove the inherent biases of per capita measures computed in the absence of isometric allometries. However, this approach is limited to urban areas, while a large portion of the world’s population still lives outside cities and rural areas dominate land use worldwide. Here, we extend the concept of SAMs to population density scale-adjusted metrics (DSAMs) to reveal relationships among different types of crime and property metrics. Our approach allows all human environments to be considered, avoids problems in the definition of urban areas, and accounts for the heterogeneity of population distributions within urban regions. By combining DSAMs, cross-correlation, and complex network analysis, we find that crime and property types have intricate and hierarchically organized relationships leading to some striking conclusions. Drugs and burglary had uncorrelated DSAMs and, to the extent property transaction values are indicators of affluence, twelve out of fourteen crime metrics showed no evidence of specifically targeting affluence. Burglary and robbery were the most connected in our network analysis and the modular structures suggest an alternative to “zero-tolerance” policies by unveiling the crime and/or property types most likely to affect each other. PMID:29470499

Estimates of brown bear abundance on Kodiak Island, Alaska

USGS Publications Warehouse

Barnes, V.G.; Smith, R.B.

1998-01-01

During 1987-94 we used capture-mark-resight (CMR) methodology and rates of observation (bears/hour and bears/100 km2) of unmarked brown bears (Ursus arctos middendorffi) during intensive aerial surveys (IAS) to estimate abundance of brown bears on Kodiak Island and to establish a baseline for monitoring population trends. CMR estimates were obtained on 3 study areas; density ranged from 216-234 bears/1,000 km2 for independent animals and 292-342 bears/1,000 km2 including dependent offspring. Rates of observation during IAS ranged from 1.4-5.4 independent bears/hour and 2.9-18.0 independent bears/100 km2. Density estimates for independent bears on each IAS area were obtained by dividing mean number of bears observed during replicate surveys by estimated sightability (based on CMR-derived sightability in areas with similar habitat. Brown bear abundance on 21 geographic units of Kodiak Island and 3 nearby islands was estimated by extrapolation from CMR and IAS data using comparisons of habitat characteristics and sport harvest information. Population estimates for independent and total bears were 1,800 and 2,600. The CMR and IAS procedures offer alternative means, depending on management objective and available resources, of measuring population trend of brown bears on Kodiak Island.

Detecting black bear source-sink dynamics using individual-based genetic graphs.

PubMed

Draheim, Hope M; Moore, Jennifer A; Etter, Dwayne; Winterstein, Scott R; Scribner, Kim T

2016-07-27

Source-sink dynamics affects population connectivity, spatial genetic structure and population viability for many species. We introduce a novel approach that uses individual-based genetic graphs to identify source-sink areas within a continuously distributed population of black bears (Ursus americanus) in the northern lower peninsula (NLP) of Michigan, USA. Black bear harvest samples (n = 569, from 2002, 2006 and 2010) were genotyped at 12 microsatellite loci and locations were compared across years to identify areas of consistent occupancy over time. We compared graph metrics estimated for a genetic model with metrics from 10 ecological models to identify ecological factors that were associated with sources and sinks. We identified 62 source nodes, 16 of which represent important source areas (net flux > 0.7) and 79 sink nodes. Source strength was significantly correlated with bear local harvest density (a proxy for bear density) and habitat suitability. Additionally, resampling simulations showed our approach is robust to potential sampling bias from uneven sample dispersion. Findings demonstrate black bears in the NLP exhibit asymmetric gene flow, and individual-based genetic graphs can characterize source-sink dynamics in continuously distributed species in the absence of discrete habitat patches. Our findings warrant consideration of undetected source-sink dynamics and their implications on harvest management of game species. © 2016 The Author(s).

Environmental supports for walking/biking and traffic safety: income and ethnicity disparities.

PubMed

Yu, Chia-Yuan

2014-10-01

The present study investigates the influence of income, ethnicity, and built environmental characteristics on the percentages of workers who walk/bike as well as on pedestrian/cyclist crash rates. Furthermore, income and ethnicity disparities are also explored. This study chose 162 census tracts in Austin as the unit of analysis. To explore income and ethnicity differences in built environments, this study examined the associations of the poverty rate, the percentage of white population, and the percentage of Hispanic population to each built environmental variable. Path models were applied to examine environmental supports of walking/biking and pedestrian/cyclist safety. Areas with high poverty rates had more biking trips and experienced more cyclist crashes, while areas with a high percentage of white population generated more walking trips and fewer pedestrian crashes. Sidewalk completeness and mixed land uses promoted walking to work but increased the crash risk for pedestrians as well. In terms of biking behaviors, road density and transit stop density both increased biking trips and cyclist crashes. Environmental designs that both encourage walking/biking trips and generate more safety threats should attract more attention from policy makers. Policies should also be more devoted to enhancing the mobility and health for areas with high poverty rates. Copyright © 2014 Elsevier Inc. All rights reserved.

[Specific features of nesting bird populations in forest-meadow-field landscapes of Meshchovsk Opolye reflect the diversity of their biotope connections].

PubMed

Kut'in, S D; Konstantinov, V M

2008-01-01

Studies on specific features of nesting bird populations in patchy landscapes were performed in Meshchovsk Opolye, Kaluga Region, from 1981 to 1990. Indices of similarity between the avifaunas of agricultural fields, lowland bogs, and small-leaved forests markedly differed from parameters of their population density in rank and value. In the series of biotopes differing in the relative amount of woodland, from central areas of small-leaved forests to forest margins and then to forest islands gradually decreasing in size, the birds segregated into two distinct groups, one characteristic of forest margins and large forest islands and the other characteristic of small and very small forest islands. Specific features of bird density distribution in forest-meadow-field landscapes of Meshchovsk Opolye reflected heterogeneity of their populations manifested in diverse connections with nesting biotopes.

Ancient Urban Ecology Reconstructed from Archaeozoological Remains of Small Mammals in the Near East

PubMed Central

Weissbrod, Lior; Malkinson, Dan; Cucchi, Thomas; Gadot, Yuval; Finkelstein, Israel; Bar-Oz, Guy

2014-01-01

Modern rapidly expanding cities generate intricate patterns of species diversity owing to immense complexity in urban spatial structure and current growth trajectories. We propose to identify and uncouple the drivers that give rise to these patterns by looking at the effect of urbanism on species diversity over a previously unexplored long temporal frame that covers early developments in urbanism. To provide this historical perspective we analyzed archaeozoological remains of small mammals from ancient urban and rural sites in the Near East from the 2nd to the 1st millennium BCE, and compared them to observations from modern urban areas. Our data show that ancient urban assemblages consistently comprised two main taxa (Mus musculus domesticus and Crocidura sp.), whereas assemblages of contemporaneous rural sites were significantly richer. Low species diversity also characterizes high-density core areas of modern cities, suggesting that similar ecological drivers have continued to operate in urban areas despite the vast growth in their size and population densities, as well as in the complexity of their technologies and social organization. Research in urban ecology has tended to emphasize the relatively high species diversity observed in low-density areas located on the outskirts of cities, where open and vegetated patches are abundant. The fact that over several millennia urban evolution did not significantly alter species diversity suggests that low diversity is an attribute of densely-populated settlements. The possibility that high diversity in peripheral urban areas arose only recently as a short-term phenomenon in urban ecology merits further research based on long-term data. PMID:24622726

Ancient urban ecology reconstructed from archaeozoological remains of small mammals in the Near East.

PubMed

Weissbrod, Lior; Malkinson, Dan; Cucchi, Thomas; Gadot, Yuval; Finkelstein, Israel; Bar-Oz, Guy

2014-01-01

Modern rapidly expanding cities generate intricate patterns of species diversity owing to immense complexity in urban spatial structure and current growth trajectories. We propose to identify and uncouple the drivers that give rise to these patterns by looking at the effect of urbanism on species diversity over a previously unexplored long temporal frame that covers early developments in urbanism. To provide this historical perspective we analyzed archaeozoological remains of small mammals from ancient urban and rural sites in the Near East from the 2nd to the 1st millennium BCE, and compared them to observations from modern urban areas. Our data show that ancient urban assemblages consistently comprised two main taxa (Mus musculus domesticus and Crocidura sp.), whereas assemblages of contemporaneous rural sites were significantly richer. Low species diversity also characterizes high-density core areas of modern cities, suggesting that similar ecological drivers have continued to operate in urban areas despite the vast growth in their size and population densities, as well as in the complexity of their technologies and social organization. Research in urban ecology has tended to emphasize the relatively high species diversity observed in low-density areas located on the outskirts of cities, where open and vegetated patches are abundant. The fact that over several millennia urban evolution did not significantly alter species diversity suggests that low diversity is an attribute of densely-populated settlements. The possibility that high diversity in peripheral urban areas arose only recently as a short-term phenomenon in urban ecology merits further research based on long-term data.

Spatial distribution of soil contamination by Toxoplasma gondii in relation to cat defecation behaviour in an urban area.

PubMed

Afonso, Eve; Lemoine, Mélissa; Poulle, Marie-Lazarine; Ravat, Marie-Caroline; Romand, Stéphane; Thulliez, Philippe; Villena, Isabelle; Aubert, Dominique; Rabilloud, Muriel; Riche, Benjamin; Gilot-Fromont, Emmanuelle

2008-07-01

In urban areas, there may be a high local risk of zoonosis due to high densities of stray cat populations. In this study, soil contamination by oocysts of Toxoplasma gondii was searched for, and its spatial distribution was analysed in relation to defecation behaviour of cats living in a high-density population present in one area of Lyon (France). Sixteen defecation sites were first identified. Cats were then repeatedly fed with marked food and the marked faeces were searched for in the defecation sites. Of 260 markers, 72 were recovered from 24 different cats. Defecation sites were frequented by up to 15 individuals. Soil samples were also examined in order to detect the presence of T. gondii using real-time PCR. The entire study area was then sampled according to cat density and vegetation cover type. Only three of 55 samples were positive and all came from defecation sites. In a second series of observations, 16 defecation sites were sampled. Eight of 62 samples tested positive, originating in five defecation sites. Laboratory experiments using experimental seeding of soil showed that the inoculated dose that can be detected in 50% of assays equals 100-1000oocysts/g, depending on the strain. This study shows that high concentrations of oocysts can be detected in soil samples using molecular methods and suggests that spatial distribution of contamination areas is highly heterogeneous. Positive samples were only found in some of the defecation sites, signifying that at-risk points for human and animal infection may be very localised.

The future of the non-timber forest product industry

Treesearch

Luc C. Duchesne; Iain Davidson-Hunt; John C. Zasada

2001-01-01

The boreal and northern forests of North America cover a vast area and have low population density with many inhabitants living in small communities. The inhabitants of these communities as well as those from urban areas are dependent on the forest resource for many commodity and non-commodity values. Although the socio-cultural outlook is changing somewhat, past and...

Characteristics of MSW and heat energy recovery between residential and commercial areas in Seoul.

PubMed

Yi, Sora; Yoo, Kee-Young; Hanaki, Keisuke

2011-03-01

This paper analyzes the amount and characteristics of municipal solid waste (MSW) according to the inhabitant density of population and the business concentration in 25 districts in Seoul. Further, the heat energy recovery and avoided CO(2) emissions of four incineration plants located in residential and commercial areas in Seoul are examined. The amount of residential waste per capita tended to increase as the density of inhabitants decreased. The amount of commercial waste per capita tended to increase as the business concentration increased. The examination of the heat energy recovery characteristics indicated that the four incineration plants produced heat energy that depended on residential or commercial areas based on population and business. The most important result regarding avoided CO(2) emissions was that commercial areas with many office-type businesses had the most effective CO(2) emission savings by combusting 1 kg of waste. Assuming the full-scale operation of the four incineration plants, the amount of saved CO(2) emissions per year was 444 Gg CO(2) and 57,006 households in Seoul can be provided with heat energy equivalent to 542,711 Nm(3) of LNG. Copyright © 2010 Elsevier Ltd. All rights reserved.

The relationship between bone mineral density and mammographic density in Korean women: the Healthy Twin study.

PubMed

Sung, Joohon; Song, Yun-Mi; Stone, Jennifer; Lee, Kayoung

2011-09-01

Mammographic density is one of the strong risk factors for breast cancer. A potential mechanism for this association is that cumulative exposure to mammographic density may reflect cumulative exposure to hormones that stimulate cell division in breast stroma and epithelium, which may have corresponding effects on breast cancer development. Bone mineral density (BMD), a marker of lifetime estrogen exposure, has been found to be associated with breast cancer. We examined the association between BMD and mammographic density in a Korean population. Study subjects were 730 Korean women selected from the Healthy Twin study. BMD (g/cm(2)) was measured with dual-energy X-ray absorptiometry. Mammographic density was measured from digital mammograms using a computer-assisted thresholding method. Linear mixed model considering familial correlations and a wide range of covariates was used for analyses. Quantitative genetic analysis was completed using SOLAR. In premenopausal women, positive associations existed between absolute dense area and BMD at ribs, pelvis, and legs, and between percent dense area and BMD at pelvis and legs. However, in postmenopausal women, there was no association between BMD at any site and mammographic density measures. An evaluation of additive genetic cross-trait correlation showed that absolute dense area had a weak-positive additive genetic cross-trait correlation with BMD at ribs and spines after full adjustment of covariates. This finding suggests that the association between mammographic density and breast cancer could, at least in part, be attributable to an estrogen-related hormonal mechanism.

Influence of polypropylene fibres on the tensile strength and thermal properties of various densities of foamed concrete

NASA Astrophysics Data System (ADS)

Jhatial, Ashfaque Ahmed; Inn, Goh Wan; Mohamad, Noridah; Johnson Alengaram, U.; Mo, Kim Hung; Abdullah, Redzuan

2017-11-01

As almost half of the world’s population now lives in the urban areas, the raise in temperature in these areas has necessitated the development of thermal insulating material. Conventional concrete absorbs solar radiation during the daytime while releasing it at night causing raise in temperature in urban areas. The thermal conductivity of 2200 kg/m3 density conventional concrete is 1.6 W/mK. Higher the thermal conductivity value, greater the heat flow through the material. To reduce this heat transfer, the construction industry has turned to lightweight foamed concrete. Foamed concrete, due to its air voids, gives excellent thermal properties and sound absorption apart from fire-resistance and self-leveling properties. But due to limited studies on different densities of foamed concrete, the thermal properties are not understood properly thus limiting its use as thermal insulating material. In this study, thermal conductivity is determined for 1400, 1600 and 1800 kg/m3 densities of foamed concrete. 0.8% of Polypropylene fibres (PP) is used to reinforce the foamed concrete and improve the mechanical properties. Based upon the results, it was found that addition of PP fibres enhances the tensile strength and slightly reduced the thermal conductivity for lower densities, while the reverse affect was noticed in 1800 kg/m3 density.

Effect of water temperature and population density on the population dynamics of Schistosoma mansoni intermediate host snails.

PubMed

McCreesh, Nicky; Arinaitwe, Moses; Arineitwe, Wilber; Tukahebwa, Edridah M; Booth, Mark

2014-11-12

Mathematical models can be used to identify areas at risk of increased or new schistosomiasis transmission as a result of climate change. The results of these models can be very different when parameterised to different species of host snail, which have varying temperature preferences. Currently, the experimental data needed by these models are available for only a few species of snail. The choice of density-dependent functions can also affect model results, but the effects of increasing densities on Biomphalaria populations have only previously been investigated in artificial aquariums. Laboratory experiments were conducted to estimate Biomphalaria sudanica mortality, fecundity and growth rates at ten different constant water temperatures, ranging from 13-32°C. Snail cages were used to determine the effects of snail densities on B. sudanica and B. stanleyi mortality and fecundity rates in semi-natural conditions in Lake Albert. B. sudanica survival and fecundity were highest at 20°C and 22°C respectively. Growth in shell diameter was estimated to be highest at 23°C in small and medium sized snails, but the relationship between temperature and growth was not clear. The fecundity of both B. sudanica and B. stanleyi decreased by 72-75% with a four-fold increase in population density. Increasing densities four-fold also doubled B. stanleyi mortality rates, but had no effect on the survival of B. sudanica. The optimum temperature for fecundity was lower for B. sudanica than for previously studied species of Biomphalaria. In contrast to other Biomphalaria species, B. sudanica have a distinct peak temperature for survival, as opposed to a plateau of highly suitable temperatures. For both B. stanleyi and B. sudanica, fecundity decreased with increasing population densities. This means that snail populations may experience large fluctuations in numbers, even in the absence of any external factors such as seasonal temperature changes. Survival also decreased with increasing density for B. stanleyi, in contrast to B. sudanica and other studied Biomphalaria species where only fecundity has been shown to decrease.

Positive correlation between genetic diversity and fitness in a large, well-connected metapopulation.

PubMed

Vandewoestijne, Sofie; Schtickzelle, Nicolas; Baguette, Michel

2008-11-05

Theory predicts that lower dispersal, and associated gene flow, leads to decreased genetic diversity in small isolated populations, which generates adverse consequences for fitness, and subsequently for demography. Here we report for the first time this effect in a well-connected natural butterfly metapopulation with high population densities at the edge of its distribution range. We demonstrate that: (1) lower genetic diversity was coupled to a sharp decrease in adult lifetime expectancy, a key component of individual fitness; (2) genetic diversity was positively correlated to the number of dispersing individuals (indicative of landscape functional connectivity) and adult population size; (3) parameters inferred from capture-recapture procedures (population size and dispersal events between patches) correlated much better with genetic diversity than estimates usually used as surrogates for population size (patch area and descriptors of habitat quality) and dispersal (structural connectivity index). Our results suggest that dispersal is a very important factor maintaining genetic diversity. Even at a very local spatial scale in a metapopulation consisting of large high-density populations interconnected by considerable dispersal rates, genetic diversity can be decreased and directly affect the fitness of individuals. From a biodiversity conservation perspective, this study clearly shows the benefits of both in-depth demographic and genetic analyses. Accordingly, to ensure the long-term survival of populations, conservation actions should not be blindly based on patch area and structural isolation. This result may be especially pertinent for species at their range margins, particularly in this era of rapid environmental change.

Composition and distribution of the health workforce in India: estimates based on data from the National Sample Survey.

PubMed

Rao, Krishna D; Shahrawat, Renu; Bhatnagar, Aarushi

2016-09-01

The availability of reliable and comprehensive information on the health workforce is crucial for workforce planning. In India, routine information sources on the health workforce are incomplete and unreliable. This paper addresses this issue and provides a comprehensive picture of India's health workforce. Data from the 68th round (July 2011 to June 2012) of the National Sample Survey on the Employment and unemployment situation in India were analysed to produce estimates of the health workforce in India. The estimates were based on self-reported occupations, categorized using a combination of both National Classification of Occupations (2004) and National Industrial Classification (2008) codes. Findings suggest that in 2011-2012, there were 2.5 million health workers (density of 20.9 workers per 10 000 population) in India. However, 56.4% of all health workers were unqualified, including 42.3% of allopathic doctors, 27.5% of dentists, 56.1% of Ayurveda, yoga and naturopathy, Unani, Siddha and homoeopathy (AYUSH) practitioners, 58.4% of nurses and midwives and 69.2% of health associates. By cadre, there were 3.3 qualified allopathic doctors and 3.1 nurses and midwives per 10 000 population; this is around one quarter of the World Health Organization benchmark of 22.8 doctors, nurses and midwives per 10 000 population. Out of all qualified workers, 77.4% were located in urban areas, even though the urban population is only 31% of the total population of the country. This urban-rural difference was higher for allopathic doctors (density 11.4 times higher in urban areas) compared to nurses and midwives (5.5 times higher in urban areas). The study highlights several areas of concern: overall low numbers of qualified health workers; a large presence of unqualified health workers, particularly in rural areas; and large urban-rural differences in the distribution of qualified health workers.

São Paulo urban heat islands have a higher incidence of dengue than other urban areas.

PubMed

Araujo, Ricardo Vieira; Albertini, Marcos Roberto; Costa-da-Silva, André Luis; Suesdek, Lincoln; Franceschi, Nathália Cristina Soares; Bastos, Nancy Marçal; Katz, Gizelda; Cardoso, Vivian Ailt; Castro, Bronislawa Ciotek; Capurro, Margareth Lara; Allegro, Vera Lúcia Anacleto Cardoso

2015-01-01

Urban heat islands are characterized by high land surface temperature, low humidity, and poor vegetation, and considered to favor the transmission of the mosquito-borne dengue fever that is transmitted by the Aedes aegypti mosquito. We analyzed the recorded dengue incidence in Sao Paulo city, Brazil, in 2010-2011, in terms of multiple environmental and socioeconomic variables. Geographical information systems, thermal remote sensing images, and census data were used to classify city areas according to land surface temperature, vegetation cover, population density, socioeconomic status, and housing standards. Of the 7415 dengue cases, a majority (93.1%) mapped to areas with land surface temperature >28°C. The dengue incidence rate (cases per 100,000 inhabitants) was low (3.2 cases) in high vegetation cover areas, but high (72.3 cases) in low vegetation cover areas where the land surface temperature was 29±2°C. Interestingly, a multiple cluster analysis phenogram showed more dengue cases clustered in areas of land surface temperature >32°C, than in areas characterized as low socioeconomic zones, high population density areas, or slum-like areas. In laboratory experiments, A. aegypti mosquito larval development, blood feeding, and oviposition associated positively with temperatures of 28-32°C, indicating these temperatures to be favorable for dengue transmission. Thus, among all the variables studied, dengue incidence was most affected by the temperature. Copyright © 2014 Elsevier Editora Ltda. All rights reserved.

Using geographical information systems and cartograms as a health service quality improvement tool.

PubMed

Lovett, Derryn A; Poots, Alan J; Clements, Jake T C; Green, Stuart A; Samarasundera, Edgar; Bell, Derek

2014-07-01

Disease prevalence can be spatially analysed to provide support for service implementation and health care planning, these analyses often display geographic variation. A key challenge is to communicate these results to decision makers, with variable levels of Geographic Information Systems (GIS) knowledge, in a way that represents the data and allows for comprehension. The present research describes the combination of established GIS methods and software tools to produce a novel technique of visualising disease admissions and to help prevent misinterpretation of data and less optimal decision making. The aim of this paper is to provide a tool that supports the ability of decision makers and service teams within health care settings to develop services more efficiently and better cater to the population; this tool has the advantage of information on the position of populations, the size of populations and the severity of disease. A standard choropleth of the study region, London, is used to visualise total emergency admission values for Chronic Obstructive Pulmonary Disease and bronchiectasis using ESRI's ArcGIS software. Population estimates of the Lower Super Output Areas (LSOAs) are then used with the ScapeToad cartogram software tool, with the aim of visualising geography at uniform population density. An interpolation surface, in this case ArcGIS' spline tool, allows the creation of a smooth surface over the LSOA centroids for admission values on both standard and cartogram geographies. The final product of this research is the novel Cartogram Interpolation Surface (CartIS). The method provides a series of outputs culminating in the CartIS, applying an interpolation surface to a uniform population density. The cartogram effectively equalises the population density to remove visual bias from areas with a smaller population, while maintaining contiguous borders. CartIS decreases the number of extreme positive values not present in the underlying data as can be found in interpolation surfaces. This methodology provides a technique for combining simple GIS tools to create a novel output, CartIS, in a health service context with the key aim of improving visualisation communication techniques which highlight variation in small scale geographies across large regions. CartIS more faithfully represents the data than interpolation, and visually highlights areas of extreme value more than cartograms, when either is used in isolation. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

The distribution and numbers of cheetah (Acinonyx jubatus) in southern Africa

PubMed Central

Jacobson, Andrew P.; Schoonover, Rebecca F.; Groom, Rosemary J.; Horgan, Jane; Keeping, Derek; Klein, Rebecca; Marnewick, Kelly; Maude, Glyn; Melzheimer, Jörg; Mills, Gus; van der Merwe, Vincent; van der Meer, Esther; van Vuuren, Rudie J.; Wachter, Bettina

2017-01-01

Assessing the numbers and distribution of threatened species is a central challenge in conservation, often made difficult because the species of concern are rare and elusive. For some predators, this may be compounded by their being sparsely distributed over large areas. Such is the case with the cheetah Acinonyx jubatus. The IUCN Red List process solicits comments, is democratic, transparent, widely-used, and has recently assessed the species. Here, we present additional methods to that process and provide quantitative approaches that may afford greater detail and a benchmark against which to compare future assessments. The cheetah poses challenges, but also affords unique opportunities. It is photogenic, allowing the compilation of thousands of crowd-sourced data. It is also persecuted for killing livestock, enabling estimation of local population densities from the numbers persecuted. Documented instances of persecution in areas with known human and livestock density mean that these data can provide an estimate of where the species may or may not occur in areas without observational data. Compilations of extensive telemetry data coupled with nearly 20,000 additional observations from 39 sources show that free-ranging cheetahs were present across approximately 789,700 km2 of Namibia, Botswana, South Africa, and Zimbabwe (56%, 22%, 12% and 10% respectively) from 2010 to 2016, with an estimated adult population of 3,577 animals. We identified a further 742,800 km2 of potential cheetah habitat within the study region with low human and livestock densities, where another ∼3,250 cheetahs may occur. Unlike many previous estimates, we make the data available and provide explicit information on exactly where cheetahs occur, or are unlikely to occur. We stress the value of gathering data from public sources though these data were mostly from well-visited protected areas. There is a contiguous, transboundary population of cheetah in southern Africa, known to be the largest in the world. We suggest that this population is more threatened than believed due to the concentration of about 55% of free-ranging individuals in two ecoregions. This area overlaps with commercial farmland with high persecution risk; adult cheetahs were removed at the rate of 0.3 individuals per 100 km2 per year. Our population estimate for confirmed cheetah presence areas is 11% lower than the IUCN’s current assessment for the same region, lending additional support to the recent call for the up-listing of this species from vulnerable to endangered status. PMID:29250465

The distribution and numbers of cheetah (Acinonyx jubatus) in southern Africa.

PubMed

Weise, Florian J; Vijay, Varsha; Jacobson, Andrew P; Schoonover, Rebecca F; Groom, Rosemary J; Horgan, Jane; Keeping, Derek; Klein, Rebecca; Marnewick, Kelly; Maude, Glyn; Melzheimer, Jörg; Mills, Gus; van der Merwe, Vincent; van der Meer, Esther; van Vuuren, Rudie J; Wachter, Bettina; Pimm, Stuart L

2017-01-01

Assessing the numbers and distribution of threatened species is a central challenge in conservation, often made difficult because the species of concern are rare and elusive. For some predators, this may be compounded by their being sparsely distributed over large areas. Such is the case with the cheetah Acinonyx jubatus. The IUCN Red List process solicits comments, is democratic, transparent, widely-used, and has recently assessed the species. Here, we present additional methods to that process and provide quantitative approaches that may afford greater detail and a benchmark against which to compare future assessments. The cheetah poses challenges, but also affords unique opportunities. It is photogenic, allowing the compilation of thousands of crowd-sourced data. It is also persecuted for killing livestock, enabling estimation of local population densities from the numbers persecuted. Documented instances of persecution in areas with known human and livestock density mean that these data can provide an estimate of where the species may or may not occur in areas without observational data. Compilations of extensive telemetry data coupled with nearly 20,000 additional observations from 39 sources show that free-ranging cheetahs were present across approximately 789,700 km 2 of Namibia, Botswana, South Africa, and Zimbabwe (56%, 22%, 12% and 10% respectively) from 2010 to 2016, with an estimated adult population of 3,577 animals. We identified a further 742,800 km 2 of potential cheetah habitat within the study region with low human and livestock densities, where another ∼3,250 cheetahs may occur. Unlike many previous estimates, we make the data available and provide explicit information on exactly where cheetahs occur, or are unlikely to occur. We stress the value of gathering data from public sources though these data were mostly from well-visited protected areas. There is a contiguous, transboundary population of cheetah in southern Africa, known to be the largest in the world. We suggest that this population is more threatened than believed due to the concentration of about 55% of free-ranging individuals in two ecoregions. This area overlaps with commercial farmland with high persecution risk; adult cheetahs were removed at the rate of 0.3 individuals per 100 km 2 per year. Our population estimate for confirmed cheetah presence areas is 11% lower than the IUCN's current assessment for the same region, lending additional support to the recent call for the up-listing of this species from vulnerable to endangered status.

Atmospheric 14 C CO 2 variations in Japan during 1982--1999 based on 14 C measurements of rice grains.

PubMed

Shibata, Setsuko; Kawano, Eiko; Nakabayashi, Takeshige

2005-08-01

(14)C in rice grains is a useful tracer of atmospheric (14)C(CO(2)). (14)C measurement in rice grains for 17 years during 1982--1999 reveals the following. There is negative correlation between Delta(14)C and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The (14)C(CO(2)) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995.

Ethnic density and area deprivation: neighbourhood effects on Māori health and racial discrimination in Aotearoa/New Zealand.

PubMed

Bécares, Laia; Cormack, Donna; Harris, Ricci

2013-07-01

Some studies suggest that ethnic minority people are healthier when they live in areas with a higher concentration of people from their own ethnic group, a so-called ethnic density effect. To date, no studies have examined the ethnic density effect among indigenous peoples, for whom connections to land, patterns of settlement, and drivers of residential location may differ from ethnic minority populations. The present study analysed the Māori sample from the 2006/07 New Zealand Health Survey to examine the association between increased Māori ethnic density, area deprivation, health, and experiences of racial discrimination. Results of multilevel regressions showed that an increase in Māori ethnic density was associated with decreased odds of reporting poor self-rated health, doctor-diagnosed common mental disorders, and experienced racial discrimination. These associations were strengthened after adjusting for area deprivation, which was consistently associated with increased odds of reporting poor health and reports of racial discrimination. Our findings show that whereas ethnic density is protective of the health and exposure to racial discrimination of Māori, this effect is concealed by the detrimental effect of area deprivation, signalling that the benefits of ethnic density must be interpreted within the current socio-political context. This includes the institutional structures and racist practices that have created existing health and socioeconomic inequities in the first place, and maintain the unequal distribution of concentrated poverty in areas of high Māori density. Addressing poverty and the inequitable distribution of socioeconomic resources by ethnicity and place in New Zealand is vital to improving health and reducing inequalities. Given the racialised nature of access to goods, services, and opportunities within New Zealand society, this also requires a strong commitment to eliminating racism. Such commitment and action will allow the benefits potentially flowing from strong communities to be fully realised. Copyright © 2013 Elsevier Ltd. All rights reserved.

The influence of socioeconomic factors on the densities of high-value cross-border species, the African elephant

PubMed Central

Slotow, Rob; Di Minin, Enrico

2016-01-01

Unprecedented poaching levels triggered by demand for ivory in Far East Asia are threatening the persistence of African elephant Loxodonta africana. Southern African countries make an important contribution to elephant conservation and could soon become the last stronghold of elephant conservation in Africa. While the ecological factors affecting elephant distribution and densities have extensively been accounted for, there is a need to understand which socioeconomic factors affect elephant numbers in order to prevent conflict over limited space and resources with humans. We used elephant count data from aerial surveys for seven years in a generalized linear model, which accounted for temporal correlation, to investigate the effect of six socioeconomic and ecological variables on the number of elephant at the country level in the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA). Important factors in predicting elephant numbers were the proportion of total land surface under cultivation, human population density and the number of tourists visiting the country. Specifically, elephant numbers were higher where the proportion of total land surface under cultivation was the lowest; where population density was the lowest and where tourist numbers had increased over the years. Our results confirm that human disturbance is affecting elephant numbers, but highlight that the benefits provided by ecotourism could help enhance elephant conservation. While future studies should include larger areas and more detailed data at the site level, we stress that the development of coordinated legislation and policies to improve land-use planning are needed to reduce the impact of increasing human populations and agriculture on elephant. PMID:27812404

Application of MODIS GPP to Forecast Risk of Hantavirus Pulmonary Syndrome Based on Fluctuations in Reservoir Population Density

NASA Astrophysics Data System (ADS)

Loehman, R.; Heinsch, F. A.; Mills, J. N.; Wagoner, K.; Running, S.

2003-12-01

Recent predictive models for hantavirus pulmonary syndrome (HPS) have used remotely sensed spectral reflectance data to characterize risk areas with limited success. We present an alternative method using gross primary production (GPP) from the MODIS sensor to estimate the effects of biomass accumulation on population density of Peromyscus maniculatus (deer mouse), the principal reservoir species for Sin Nombre virus (SNV). The majority of diagnosed HPS cases in North America are attributed to SNV, which is transmitted to humans through inhalation of excretions and secretions from infected rodents. A logistic model framework is used to evaluate MODIS GPP, temperature, and precipitation as predictors of P. maniculatus density at established trapping sites across the western United States. Rodent populations are estimated using monthly minimum number alive (MNA) data for 2000 through 2002. Both local meteorological data from nearby weather stations and 1.25 degree x 1 degree gridded data from the NASA DAO were used in the regression model to determine the spatial sensitivity of the response. MODIS eight-day GPP data (1-km resolution) were acquired and binned to monthly average and monthly sum GPP for 3km x 3km grids surrounding each rodent trapping site. The use of MODIS GPP to forecast HPS risk may result in a marked improvement over past reflectance-based risk area characterizations. The MODIS GPP product provides a vegetation dynamics estimate that is unique to disease models, and targets the fundamental ecological processes responsible for increased rodent density and amplified disease risk.

The influence of socioeconomic factors on the densities of high-value cross-border species, the African elephant.

PubMed

Selier, Sarah-Anne Jeanetta; Slotow, Rob; Di Minin, Enrico

2016-01-01

Unprecedented poaching levels triggered by demand for ivory in Far East Asia are threatening the persistence of African elephant Loxodonta africana . Southern African countries make an important contribution to elephant conservation and could soon become the last stronghold of elephant conservation in Africa. While the ecological factors affecting elephant distribution and densities have extensively been accounted for, there is a need to understand which socioeconomic factors affect elephant numbers in order to prevent conflict over limited space and resources with humans. We used elephant count data from aerial surveys for seven years in a generalized linear model, which accounted for temporal correlation, to investigate the effect of six socioeconomic and ecological variables on the number of elephant at the country level in the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA). Important factors in predicting elephant numbers were the proportion of total land surface under cultivation, human population density and the number of tourists visiting the country. Specifically, elephant numbers were higher where the proportion of total land surface under cultivation was the lowest; where population density was the lowest and where tourist numbers had increased over the years. Our results confirm that human disturbance is affecting elephant numbers, but highlight that the benefits provided by ecotourism could help enhance elephant conservation. While future studies should include larger areas and more detailed data at the site level, we stress that the development of coordinated legislation and policies to improve land-use planning are needed to reduce the impact of increasing human populations and agriculture on elephant.

Evolution of US maize (Zea mays L.) root architectural and anatomical phenes over the past 100 years corresponds to increased tolerance of nitrogen stress

PubMed Central

York, Larry M.; Galindo-Castañeda, Tania; Schussler, Jeffrey R.; Lynch, Jonathan P.

2015-01-01

Increasing the nitrogen use efficiency of maize is an important goal for food security and agricultural sustainability. In the past 100 years, maize breeding has focused on yield and above-ground phenes. Over this period, maize cultivation has changed from low fertilizer inputs and low population densities to intensive fertilization and dense populations. The authors hypothesized that through indirect selection the maize root system has evolved phenotypes suited to more intense competition for nitrogen. Sixteen maize varieties representing commercially successful lines over the past century were planted at two nitrogen levels and three planting densities. Root systems of the most recent material were 7 º more shallow, had one less nodal root per whorl, had double the distance from nodal root emergence to lateral branching, and had 14% more metaxylem vessels, but total mextaxylem vessel area remained unchanged because individual metaxylem vessels had 12% less area. Plasticity was also observed in cortical phenes such as aerenchyma, which increased at greater population densities. Simulation modelling with SimRoot demonstrated that even these relatively small changes in root architecture and anatomy could increase maize shoot growth by 16% in a high density and high nitrogen environment. The authors concluded that evolution of maize root phenotypes over the past century is consistent with increasing nitrogen use efficiency. Introgression of more contrasting root phene states into the germplasm of elite maize and determination of the functional utility of these phene states in multiple agronomic conditions could contribute to future yield gains. PMID:25795737

Distribution and sediment production of large benthic foraminifers on reef flats of the Majuro Atoll, Marshall Islands

NASA Astrophysics Data System (ADS)

Fujita, K.; Osawa, Y.; Kayanne, H.; Ide, Y.; Yamano, H.

2009-03-01

The distributions and population densities of large benthic foraminifers (LBFs) were investigated on reef flats of the Majuro Atoll, Marshall Islands. Annual sediment production by foraminifers was estimated based on population density data. Predominant LBFs were Calcarina and Amphistegina, and the population densities of these foraminifers varied with location and substratum type on reef flats. Both foraminifers primarily attached to macrophytes, particularly turf-forming algae, and were most abundant on an ocean reef flat (ORF) and in an inter-island channel near windward, sparsely populated islands. Calcarina density was higher on windward compared to leeward sides of ORFs, whereas Amphistegina density was similar on both sides of ORFs. These foraminifers were more common on the ocean side relative to the lagoon side of reef flats around a windward reef island, and both were rare or absent in nearshore zones around reef islands and on an ORF near windward, densely populated islands. Foraminiferal production rates varied with the degree to which habitats were subject to water motion and human influences. Highly productive sites (>103 g CaCO3 m-2 year-1) included an ORF and an inter-island channel near windward, sparsely populated islands, and a seaward area of a reef flat with no reef islands. Low-productivity sites (<10 g CaCO3 m-2 year-1) included generally nearshore zones of lagoonal reef flats, leeward ORFs, and a windward ORF near densely populated islands. These results suggest that the distribution and production of LBFs were largely influenced by a combination of natural environmental factors, including water motion, water depth, elevation relative to the lowest tidal level at spring tide, and the distribution of suitable substratum. The presence of reef islands may limit the distribution and production of foraminifers by altering water circulation in nearshore environments. Furthermore, increased anthropogenic factors (population and activities) may adversely affect foraminiferal distribution and production.

Prioritizing landscapes for longleaf pine conservation

USGS Publications Warehouse

Grand, James B.; Kleiner, Kevin J.

2016-01-01

We developed a spatially explicit model and map, as a decision support tool (DST), to aid conservation agencies creating or maintaining open pine ecosystems. The tool identified areas that are likely to provide the greatest benefit to focal bird populations based on a comprehensive landscape analysis. We used NLCD 2011, SSURGO, and SEGAP data to map the density of desired resources for open pine ecosystems and six focal species of birds and 2 reptiles within the historic range of longleaf pine east of the Mississippi River. Binary rasters were created of sites with desired characteristics such as land form, hydrology, land use and land cover, soils, potential habitat for focal species, and putative source populations of focal species. Each raster was smoothed using a kernel density estimator. Rasters were combined and scaled to map priority locations for the management of each focal species. Species’ rasters were combined and scaled to provide maps of overall priority for birds and for birds and reptiles. The spatial data can be used to identify high priority areas for conservation or to compare areas under consideration for maintenance or creation of open pine ecosystems.

Using simulation to improve wildlife surveys: Wintering mallards in Mississippi, USA

USGS Publications Warehouse

Pearse, A.T.; Reinecke, K.J.; Dinsmore, S.J.; Kaminski, R.M.

2009-01-01

Wildlife conservation plans generally require reliable data about population abundance and density. Aerial surveys often can provide these data; however, associated costs necessitate designing and conducting surveys efficiently. We developed methods to simulate population distributions of mallards (Anas platyrhynchos) wintering in western Mississippi, USA, by combining bird observations from three previous strip-transect surveys and habitat data from three sets of satellite images representing conditions when surveys were conducted. For each simulated population distribution, we compared 12 primary survey designs and two secondary design options by using coefficients of variation (CV) of population indices as the primary criterion for assessing survey performance. In all, 3 of the 12 primary designs provided the best precision (CV???11.7%) and performed equally well (WR08082E1d.gif diff???0.6%). Features of the designs that provided the largest gains in precision were optimal allocation of sample effort among strata and configuring the study area into five rather than four strata, to more precisely estimate mallard indices in areas of consistently high density. Of the two secondary design options, we found including a second observer to double the size of strip transects increased precision or decreased costs, whereas ratio estimation using auxiliary habitat data from satellite images did not increase precision appreciably. We recommend future surveys of mallard populations in our study area use the strata we developed, optimally allocate samples among strata, employ PPS or EPS sampling, and include two observers when qualified staff are available. More generally, the methods we developed to simulate population distributions from prior survey data provide a cost-effective method to assess performance of alternative wildlife surveys critical to informing management decisions, and could be extended to account for effects of detectability on estimates of true abundance. ?? 2009 CSIRO.