Xylem vulnerability curves of canopy branches of mature trees from Caxiuana and Tapajos National Forests, Para, Brazil

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

Powell, Thomas; Moorcroft, Paul

Raw data for xylem vulnerability curves measured on upper canopy branches of mature trees from the Caxiuana and Tapajos National Forests, Para, Brazil. Tapajos samples were harvested from km67 transects, which is nearby the decommissioned throughfall-exclusion, drought-experiment plots. Caxiuana samples were harvested from trees growing in the throughfall-exclusion, drought-experiment plots. Data were collected in 2011 and 2012. Dataset includes: date of measurement, site ID, plot ID, tree ID (species, tree tag #), xylem pressure, percent loss of conductivity. Air injection method was used. Data reference: Powell et al. (2017) Differences in xylem cavitation resistance and leaf hydraulic traits explain differencesmore » in drought tolerance among mature Amazon rainforest trees. Global Change Biology.« less

Oregon transect: Comparison of leaf-level reflectance with canopy-level and modelled reflectance

NASA Technical Reports Server (NTRS)

Johnson, Lee F.; Baret, Frederic; Peterson, David L.

1992-01-01

The Oregon Transect Ecosystem Research (OTTER) project involves the collection of a variety of remotely-sensed and in situ measurements for characterization of forest biophysical and biochemical parameters. The project includes nine study plots located along an environmental gradient in west-central Oregon, extending from the Pacific coast inland approximately 300km. These plots represent a broad range in ecosystem structure and function. Within the OTTER project, the sensitivity of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) signal to absorption by foliar biochemicals is being examined. AVIRIS data were acquired over all plots in conjunction with the four OTTER Multi-sensor Aircraft Campaigns spanning the growing season. Foilage samples were gathered during each campaign for biochemical determination (at Ames Research Center), to estimate stand-level constituency at each plot. Directional-hemispheric leaf reflectance throughout the 400-2400nm region was measured in the laboratory as an aid to interpreting concurrent AVIRIS data. Obtaining leaf spectra in this manner reduces or eliminates the confounding influences of atmosphere, canopy architecture, and reflectance by woody components, understory, and exposed soils which are present in airborne observations. These laboratory spectra were compared to simulated spectra derived by inverting the PROSPECT leaf-level canopy reflectance derived from AVIRIS data by use of the LOWTRAN-7 atmospheric radiative-transfer model.

Temporal variation in earthworm abundance and diversity along hedgerow-to-field transects in contrasting agricultural land uses

NASA Astrophysics Data System (ADS)

Prendergast-Miller, Miranda T.; Jones, David; Hodson, Mark E.

2017-04-01

Earthworms are regarded as ecosystem engineers, integral to soil processes such as aggregation, nutrient cycling, water infiltration, plant growth and microbial function. Earthworm surveys were conducted for one year on hedge-to-field transects in arable and pasture fields (Yorkshire, UK). The transects incorporated hedgerow and field margin habitats and extended 60 m into the arable or pasture field. At defined distances, earthworm abundance and biomass were recorded, and earthworms were identified to species and ecological group. Soil density, moisture and temperature were also measured. Additional transects were surveyed on experimental plots with arable-to-ley conversions in the arable fields (wheat crop to grass-clover ley), and tilled plots in the pasture fields (grass-clover ley to wheat crop). The conversion plots were established to determine the benefit of grass-clover leys on soil function; and the tilled pasture plots were established to compare the impact of conventional or minimum tillage practices on earthworm abundance and diversity. A baseline survey was conducted before establishment of the experimental ley and tillage plots. The results showed differences in earthworm abundance, with greater earthworm numbers in the pasture soils compared to arable soils. In both soils, abundance of ecological group was endogeic > epigeic > anecic, and each group was dominated by the same species: Allolobophora chlorotica, Lumbricus castaneus and Apporectodea longa. After one year of treatment, there was some indication of increased earthworm abundance in the arable-to-ley conversion strips. Conversely, tillage in the pasture plots tended to reduce earthworm abundance, and conventional tillage tended to have the greater impact. However, within these major changes, there was also evidence of spatial (distance along transect; field location) and temporal (seasonal) variation on earthworm abundance. Although conversion to ley or tillage did not alter the pattern of ecological grouping, there were changes in species diversity which will also be discussed. This earthworm study is part of a larger project which aims to (1) link soil biodiversity (microbes, soil fauna) with soil function (productivity, water infiltration, drought resilience), and (2) demonstrate the benefits of grass-clover leys and minimum tillage in boosting soil biodiversity, soil function, and hence, sustainable agricultural productivity.

Digital soil mapping using remote sensing indices, terrain attributes, and vegetation features in the rangelands of northeastern Iran.

PubMed

Mahmoudabadi, Ebrahim; Karimi, Alireza; Haghnia, Gholam Hosain; Sepehr, Adel

2017-09-11

Digital soil mapping has been introduced as a viable alternative to the traditional mapping methods due to being fast and cost-effective. The objective of the present study was to investigate the capability of the vegetation features and spectral indices as auxiliary variables in digital soil mapping models to predict soil properties. A region with an area of 1225 ha located in Bajgiran rangelands, Khorasan Razavi province, northeastern Iran, was chosen. A total of 137 sampling sites, each containing 3-5 plots with 10-m interval distance along a transect established based on randomized-systematic method, were investigated. In each plot, plant species names and numbers as well as vegetation cover percentage (VCP) were recorded, and finally one composite soil sample was taken from each transect at each site (137 soil samples in total). Terrain attributes were derived from a digital elevation model, different bands and spectral indices were obtained from the Landsat7 ETM+ images, and vegetation features were calculated in the plots, all of which were used as auxiliary variables to predict soil properties using artificial neural network, gene expression programming, and multivariate linear regression models. According to R 2 RMSE and MBE values, artificial neutral network was obtained as the most accurate soil properties prediction function used in scorpan model. Vegetation features and indices were more effective than remotely sensed data and terrain attributes in predicting soil properties including calcium carbonate equivalent, clay, bulk density, total nitrogen, carbon, sand, silt, and saturated moisture capacity. It was also shown that vegetation indices including NDVI, SAVI, MSAVI, SARVI, RDVI, and DVI were more effective in estimating the majority of soil properties compared to separate bands and even some soil spectral indices.

Presence or frequency of woody plants in vegetation samples in the costal plain and interior low plateau of Tennessee

Treesearch

H.R. Deselm; W.L. Patterson; Vernon Bates; D.B. Durham; R.K. Abernethy; D.C. Eagar; R.P. Ford; Paul.B. Hamel

1999-01-01

Records of the woody flora, based on nearly 1500 plotslstands of mainly forest vegetation of West and Middle Tennessee, have been compiled. The data are from 1155 transects (data collected 1993-1995) and 343 0.1 ha plots (data collected 1985-1986). Taxa total 246 species and lesser forms. The dominant woody plants sort into many community types occupying the small...

Cervid forage utilization in noncommercially thinned ponderosa pine forests

USGS Publications Warehouse

Gibbs, M.C.; Jenks, J.A.; Deperno, C.S.; Sowell, B.F.; Jenkins, Kurt J.

2004-01-01

To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked plants and percent-plants-grazed were used to evaluate forage utilization. Standing biomass of graminoids, shrubs, and forbs increased (P 0.05) across treatments. Forb use averaged less than 5% within sampling periods when measured as percent-weight-removed and percent-of-plants grazed and did not differ among treatments. Results of pellet group surveys indicated that cervids were primarily using meadow habitats. When averaged over the 2 years, forbs were the major forage class in deer diets, whereas graminoids were the major forage class in diets of elk.

Hydrographic Variability off the Coast of Oman

NASA Astrophysics Data System (ADS)

Belabbassi, L.; Dimarco, S. F.; Jochens, A. E.; Al Gheilani, H.; Wang, Z.

2010-12-01

Data from hydrographic transects made in 2001 and 2002 and between 2007 and 2009 were obtained from the Oman Ministry of Fisheries Wealth. Property-depth plots of temperature, salinity, and dissolved oxygen were produced for all transects and in all months for which data were available. These were analyzed for temporal and spatial variability. For all transects, there exist large variability on various timescales, with strong spatial variability. Two common features that are seen in the hydrographic data sets are the Persian Gulf Water (PGW) and a layer of continuous low oxygen concentrations in the lower part of the water column. Plots of salinity produced for transects located in the northern part of the Gulf of Oman show a one-unit increase in salinity of the water at the bottom of deepest station during the months of August and September as compared to the other months. Similarly, cross-shelf contour plots of temperature shows an increase in water temperature near the bottom station during the months of August and September. These indicate the presence of the PGW outflow in the northern part of the Gulf of Oman. For dissolved oxygen distributions, hydrographic transects that did not extend far offshore show monthly differences in the presence of water with low oxygen concentrations. For transects that do extend far offshore and also show a layer of low oxygen water throughout the year, there is generally a monthly difference on whether this water is found close to the surface or deeper in the water column. The variability seen in the data could only be explained by comparing these data to data collected from the real time cable ocean observing system installed by Lighthouse R &D Enterprise in the Oman Sea and the Arabian Sea in 2005. The analysis of these data reveal that the variability observed is related to processes such as ocean conditions, monsoonal cycle, and extreme weather events.

Modern pollen and stomate deposition in lake surface sediments from across the treeline on the Kola Peninsula, Russia.

PubMed

Gervais, B R.; MacDonald, G M.

2001-04-01

We sampled and analyzed surface sediments from 31 lakes along a latitudinal transect crossing the coniferous treeline on the Kola Peninsula, Russia. The major vegetation zones along the transect were tundra, birch-forest tundra, pine-forest tundra, and forest. The results indicate that the major vegetation types in our study area have distinct pollen spectra. Sum-of-squares cluster analysis and principal components analysis (PCA) groupings of pollen sites correspond to the major vegetation zones. PCA ordination of taxa indicates that the first axis separates taxa typical of the forest zone (Pinus, Picea) from taxa typical of tundra and forest-tundra zones (Polypodiaceae, Ericaceae, and Betula). The current position of the coniferous treeline, defined in our region by Pinus sylvestris, occurs roughly where Pinus pollen values reach 35% or greater. Arboreal pollen (AP)/non-arboreal pollen (NAP) ratios were calculated for each site and plotted against geographic distance along the transect. AP/NAP ratios of 7 or greater are found within pine-forest tundra and forest vegetation zones. Pinus stomates (dispersed stomatal guard cells) are absent from sites north of the coniferous treeline and all but two samples from the forested sites contain stomates. Stomate concentrations among the samples are highly variable and range from 10 to 458 per ml and positively correlate with the changing Pinus pollen values.

Dynamics of composition and structure in an old Sequoia sempervirens forest

USGS Publications Warehouse

Busing, R.T.; Fujimori, T.

2002-01-01

Dynamics of a Sequoia sempervirens forest in northern California were studied with long-term plot data (1.44 ha) and recent transect data. The study was conducted in an old stand (> 1100 yr) on alluvial flats. Over three decades (1972-2001), changes in the composition and structure of the tree stratum were minor. Sequoia maintained a broad distribution of stem diameters throughout the period. Annual rates of Sequoia mortality (0.0029) and ingrowth (0.0029) were low, reflecting the great longevity of Sequoia and the slow canopy turnover of the study forest. Transect data also indicated a low frequency of canopy gap disturbance (??? 0.4% of total land area per yr), but gap size was potentially large (> 0.1 ha) and the fraction of area in gaps (ca. 20%) was similar to other temperate forests. Regeneration quadrats sampled along transects, in gap centers, and on logs revealed that Sequoia regeneration is elevated at gap edges. The longevity of Sequoia and its response to gap disturbances ensure that it will remain a dominant species in the study forest.

A double-observer method for reducing bias in faecal pellet surveys of forest ungulates

USGS Publications Warehouse

Jenkins, K.J.; Manly, B.F.J.

2008-01-01

1. Faecal surveys are used widely to study variations in abundance and distribution of forest-dwelling mammals when direct enumeration is not feasible. The utility of faecal indices of abundance is limited, however, by observational bias and variation in faecal disappearance rates that obscure their relationship to population size. We developed methods to reduce variability in faecal surveys and improve reliability of faecal indices. 2. We used double-observer transect sampling to estimate observational bias of faecal surveys of Roosevelt elk Cervus elaphus roosevelti and Columbian black-tailed deer Odocoileus hemionus columbianus in Olympic National Park, Washington, USA. We also modelled differences in counts of faecal groups obtained from paired cleared and uncleared transect segments as a means to adjust standing crop faecal counts for a standard accumulation interval and to reduce bias resulting from variable decay rates. 3. Estimated detection probabilities of faecal groups ranged from < 0.2-1.0 depending upon the observer, whether the faecal group was from elk or deer, faecal group size, distance of the faecal group from the sampling transect, ground vegetation cover, and the interaction between faecal group size and distance from the transect. 4. Models of plot-clearing effects indicated that standing crop counts of deer faecal groups required 34% reduction on flat terrain and 53% reduction on sloping terrain to represent faeces accumulated over a standard 100-day interval, whereas counts of elk faecal groups required 0% and 46% reductions on flat and sloping terrain, respectively. 5. Synthesis and applications. Double-observer transect sampling provides a cost-effective means of reducing observational bias and variation in faecal decay rates that obscure the interpretation of faecal indices of large mammal abundance. Given the variation we observed in observational bias of faecal surveys and persistence of faeces, we emphasize the need for future researchers to account for these comparatively manageable sources of bias before comparing faecal indices spatially or temporally. Double-observer sampling methods are readily adaptable to study variations in faecal indices of large mammals at the scale of the large forest reserve, natural area, or other forested regions when direct estimation of populations is problematic. ?? 2008 The Authors.

Bromus Tectorum (Cheatgrass): Monitoring An Invasion For 10 Years

USDA-ARS?s Scientific Manuscript database

In a Krascheninnikovia lanata (winterfat) community in the Honey Lake Valley of northeastern, CA we have monitored the effect of B. tectorum (a Eurasian exotic annual grass) invasion on surface soil properties. In 1990 a transect of 13 plots, 50 m apart was established, at which time only plots 1-5 ...

Bird population and habitat surveys in urban areas

USGS Publications Warehouse

DeGraaf, R.M.; Geis, A.D.; Healy, P.A.

1991-01-01

Breeding bird populations in six habitats in Columbia. MD, were studied to develop procedures suitable for measuring bird use of residential areas and to identify habitat characteristics that define the distribution of various common bird species. A procedure to measure bird use based on 4-min transect counts on plots measuring 91 m ? 91 m proved better than point counts. Transect counts reduced many of the problems associated with counting birds in urban areas, such as varying noise and visibility. Eighty percent of observations were recorded in the first 4 min. Habitat measurement procedures were examined also. It was found that a subsample of woody tree and shrub crown volumes made on 0.2 ha was highly correlated with similar measures made on 0.8-ha plots.

Quantifying small-scale spatio-temporal variability of snow stratigraphy in forests based on high-resolution snow penetrometry

NASA Astrophysics Data System (ADS)

Teich, M.; Hagenmuller, P.; Bebi, P.; Jenkins, M. J.; Giunta, A. D.; Schneebeli, M.

2017-12-01

Snow stratigraphy, the characteristic layering within a seasonal snowpack, has important implications for snow remote sensing, hydrology and avalanches. Forests modify snowpack properties through interception, wind speed reduction, and changes to the energy balance. The lack of snowpack observations in forests limits our ability to understand the evolution of snow stratigraphy and its spatio-temporal variability as a function of forest structure and to observe snowpack response to changes in forest cover. We examined the snowpack under canopies of a spruce forest in the central Rocky Mountains, USA, using the SnowMicroPen (SMP), a high resolution digital penetrometer. Weekly-repeated penetration force measurements were recorded along 10 m transects every 0.3 m in winter 2015 and bi-weekly along 20 m transects every 0.5 m in 2016 in three study plots beneath canopies of undisturbed, bark beetle-disturbed and harvested forest stands, and an open meadow. To disentangle information about layer hardness and depth variabilities, and to quantitatively compare the different SMP profiles, we applied a matching algorithm to our dataset, which combines several profiles by automatically adjusting their layer thicknesses. We linked spatial and temporal variabilities of penetration force and depth, and thus snow stratigraphy to forest and meteorological conditions. Throughout the season, snow stratigraphy was more heterogeneous in undisturbed but also beneath bark beetle-disturbed forests. In contrast, and despite remaining small diameter trees and woody debris, snow stratigraphy was rather homogenous at the harvested plot. As expected, layering at the non-forested plot varied only slightly over the small spatial extent sampled. At the open and harvested plots, persistent crusts and ice lenses were clearly present in the snowpack, while such hard layers barely occurred beneath undisturbed and disturbed canopies. Due to settling, hardness significantly increased with depth at open and harvested plots, which was less distinctive at the other two plots. Our results contribute to the general understanding of forest-snowpack interactions and, if combined with density and specific surface area estimates, can be used to validate snowpack and microwave models for avalanche formation and SWE retrieval in forests.

Phytoplankton assemblages within the Chesapeake Bay plume and adjacent waters of the continental shelf

NASA Technical Reports Server (NTRS)

Marshall, H. G.

1981-01-01

The Chesapeake Bay plume was identified and plotted in relation to the presence and high concentrations of phytoplankton assemblages. Seasonal differences occurred within the plume during the collection period, with Skeletonema costatum and an ultraplankton component the dominant forms. Patchiness was found along the transects, with variations in composition and concentrations common on consecutive day sampling within the plume in its movement along the shelf. The presence of 236 species is noted, with their presence indicated for plume and shelf stations during the March, June, and October 1980 collections.

Monitoring shifts in plant diversity in response to climate change: A method for landscapes

USGS Publications Warehouse

Stohlgren, T.J.; Owen, A.J.; Lee, M.

2000-01-01

Improved sampling designs are needed to detect, monitor, and predict plant migrations and plant diversity changes caused by climate change and other human activities. We propose a methodology based on multi-scale vegetation plots established across forest ecotones which provide baseline data on patterns of plant diversity, invasions of exotic plant species, and plant migrations at landscape scales in Rocky Mountain National Park, Colorado, USA. We established forty two 1000-m2 plots in relatively homogeneous forest types and the ecotones between them on 14 vegetation transects. We found that 64% of the variance in understory species distributions at landscape scales were described generally by gradients of elevation and under-canopy solar radiation. Superimposed on broad-scale climatic gradients are small-scale gradients characterized by patches of light, pockets of fertile soil, and zones of high soil moisture. Eighteen of the 42 plots contained at least one exotic species; monitoring exotic plant invasions provides a means to assess changes in native plant diversity and plant migrations. Plant species showed weak affinities to overstory vegetation types, with 43% of the plant species found in three or more vegetation types. Replicate transects along several environmental gradients may provide the means to monitor plant diversity and species migrations at landscape scales because: (1) ecotones may play crucial roles in expanding the geophysiological ranges of many plant species; (2) low affinities of understory species to overstory forest types may predispose vegetation types to be resilient to rapid environmental change; and (3) ecotones may help buffer plant species from extirpation and extinction.

Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

PubMed

Verschave, S H; Levecke, B; Duchateau, L; Vercruysse, J; Charlier, J

2015-06-15

Assessing levels of pasture larval contamination is frequently used to study the population dynamics of the free-living stages of parasitic nematodes of livestock. Direct quantification of infective larvae (L3) on herbage is the most applied method to measure pasture larval contamination. However, herbage collection remains labour intensive and there is a lack of studies addressing the variation induced by the sampling method and the required sample size. The aim of this study was (1) to compare two different sampling methods in terms of pasture larval count results and time required to sample, (2) to assess the amount of variation in larval counts at the level of sample plot, pasture and season, respectively and (3) to calculate the required sample size to assess pasture larval contamination with a predefined precision using random plots across pasture. Eight young stock pastures of different commercial dairy herds were sampled in three consecutive seasons during the grazing season (spring, summer and autumn). On each pasture, herbage samples were collected through both a double-crossed W-transect with samples taken every 10 steps (method 1) and four random located plots of 0.16 m(2) with collection of all herbage within the plot (method 2). The average (± standard deviation (SD)) pasture larval contamination using sampling methods 1 and 2 was 325 (± 479) and 305 (± 444)L3/kg dry herbage (DH), respectively. Large discrepancies in pasture larval counts of the same pasture and season were often seen between methods, but no significant difference (P = 0.38) in larval counts between methods was found. Less time was required to collect samples with method 2. This difference in collection time between methods was most pronounced for pastures with a surface area larger than 1 ha. The variation in pasture larval counts from samples generated by random plot sampling was mainly due to the repeated measurements on the same pasture in the same season (residual variance component = 6.2), rather than due to pasture (variance component = 0.55) or season (variance component = 0.15). Using the observed distribution of L3, the required sample size (i.e. number of plots per pasture) for sampling a pasture through random plots with a particular precision was simulated. A higher relative precision was acquired when estimating PLC on pastures with a high larval contamination and a low level of aggregation compared to pastures with a low larval contamination when the same sample size was applied. In the future, herbage sampling through random plots across pasture (method 2) seems a promising method to develop further as no significant difference in counts between the methods was found and this method was less time consuming. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance of quantitative vegetation sampling methods across gradients of cover in Great Basin plant communities

USGS Publications Warehouse

Pilliod, David S.; Arkle, Robert S.

2013-01-01

Resource managers and scientists need efficient, reliable methods for quantifying vegetation to conduct basic research, evaluate land management actions, and monitor trends in habitat conditions. We examined three methods for quantifying vegetation in 1-ha plots among different plant communities in the northern Great Basin: photography-based grid-point intercept (GPI), line-point intercept (LPI), and point-quarter (PQ). We also evaluated each method for within-plot subsampling adequacy and effort requirements relative to information gain. We found that, for most functional groups, percent cover measurements collected with the use of LPI, GPI, and PQ methods were strongly correlated. These correlations were even stronger when we used data from the upper canopy only (i.e., top “hit” of pin flags) in LPI to estimate cover. PQ was best at quantifying cover of sparse plants such as shrubs in early successional habitats. As cover of a given functional group decreased within plots, the variance of the cover estimate increased substantially, which required more subsamples per plot (i.e., transect lines, quadrats) to achieve reliable precision. For GPI, we found that that six–nine quadrats per hectare were sufficient to characterize the vegetation in most of the plant communities sampled. All three methods reasonably characterized the vegetation in our plots, and each has advantages depending on characteristics of the vegetation, such as cover or heterogeneity, study goals, precision of measurements required, and efficiency needed.

Soil moisture and vegetation patterns in northern California forests

Treesearch

James R. Griffin

1967-01-01

Twenty-nine soil-vegetation plots were studied in a broad transect across the southern Cascade Range. Variations in soil moisture patterns during the growing season and in soil moisture tension values are discussed. Plot soil moisture values for 40- and 80-cm. depths in August and September are integrated into a soil drought index. Vegetation patterns are described in...

Highly variable aerodynamic roughness length (z0) for a hummocky debris-covered glacier

NASA Astrophysics Data System (ADS)

Miles, Evan S.; Steiner, Jakob F.; Brun, Fanny

2017-08-01

The aerodynamic roughness length (z0) is an essential parameter in surface energy balance studies, but few literature values exist for debris-covered glaciers. We use microtopographic and aerodynamic methods to assess the spatial variability of z0 for Lirung Glacier, Nepal. We apply structure from motion to produce digital elevation models for three nested domains: five 1 m2 plots, a 21,300 m2 surface depression, and the lower 550,000 m2 of the debris-mantled tongue. Wind and temperature sensor towers were installed in the vicinity of the plots within the surface depression in October 2014. We calculate z0 according to a variety of transect-based microtopographic parameterizations for each plot, then develop a grid version of the algorithms by aggregating data from all transects. This grid approach is applied to the surface depression digital elevation model to characterize z0 spatial variability. The algorithms reproduce the same variability among transects and plots, but z0 estimates vary by an order of magnitude between algorithms. Across the study depression, results from different algorithms are strongly correlated. Using Monin-Obukov similarity theory, we derive z0 values from the meteorological data. Using different stability criteria, we derive median values of z0 between 0.03 m and 0.05 m, but with considerable uncertainty due to the glacier's complex topography. Considering estimates from these algorithms, results suggest that z0 varies across Lirung Glacier between ˜0.005 m (gravels) to ˜0.5 m (boulders). Future efforts should assess the importance of such variable z0 values in a distributed energy balance model.

Tropical Rain Forest Structure, Tree Growth and Dynamics along a 2700-m Elevational Transect in Costa Rica

PubMed Central

Clark, David B.; Hurtado, Johanna; Saatchi, Sassan S.

2015-01-01

Rapid biological changes are expected to occur on tropical elevational gradients as species migrate upslope or go extinct in the face of global warming. We established a series of 9 1-ha plots in old-growth tropical rainforest in Costa Rica along a 2700 m relief elevational gradient to carry out long-term monitoring of tropical rain forest structure, dynamics and tree growth. Within each plot we mapped, identified, and annually measured diameter for all woody individuals with stem diameters >10 cm for periods of 3-10 years. Wood species diversity peaked at 400-600 m and decreased substantially at higher elevations. Basal area and stem number varied by less than two-fold, with the exception of the 2800 m cloud forest summit, where basal area and stem number were approximately double that of lower sites. Canopy gaps extending to the forest floor accounted for <3% of microsites at all elevations. Height of highest crowns and the coefficient of variation of crown height both decreased with increasing elevation. Rates of turnover of individuals and of stand basal area decreased with elevation, but rates of diameter growth and stand basal area showed no simple relation to elevation. We discuss issues encountered in the design and implementation of this network of plots, including biased sampling, missing key meteorological and biomass data, and strategies for improving species-level research. Taking full advantage of the major research potential of tropical forest elevational transects will require sustaining and extending ground based studies, incorporation of new remotely-sensed data and data-acquisition platforms, and new funding models to support decadal research on these rapidly-changing systems. PMID:25856163

SPRUCE Bog Surface Elevation Assessments with SET Instrument Beginning in 2013

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

Hanson, Paul J; Phillips, Jana R; Brice, Deanne J

This data set reports plot-specific bog surface elevation measurements collected with the SPRUCE Elevation Transect (SET) instrument. Measurements are reported as absolute elevation in meters above mean sea level for two locations in each of the SPRUCE experimental treatment plots and additional ambient boardwalk plots -- 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20 and 21. This data set reports measurements collected from June 2013 through August 2017, but it will be appended annually as new data are collected.

Effects of climate and geochemistry on soil organic matter stabilization and greenhouse gas emissions along altitudinal transects in different mountain regions

NASA Astrophysics Data System (ADS)

Griepentrog, Marco; Bodé, Samuel; Boudin, Mathieu; Dercon, Gerd; Doetterl, Sebastian; Matulanya, Machibya; Msigwa, Anna; Vermeir, Pieter; Boeckx, Pascal

2017-04-01

Terrestrial ecosystems are strongly influenced by climate change and soils are key compartments of the global carbon (C) cycle in terms of their potential to store or release significant amounts of C. This study is part of the interregional IAEA Technical Cooperation Project ``Assessing the Impact of Climate Change and its Effects on Soil and Water Resources in Polar and Mountainous Regions (INT5153)'' aiming to improve the understanding of climate change impacts on soil organic carbon (SOC) in fragile polar and high mountainous ecosystems at local and global scale for their better management and conservation. The project includes 13 benchmark sites situated around the world. Here we present novel data from altitudinal transects of three different mountain regions (Mount Kilimanjaro, Tanzania; Mount Gongga, China; Cordillera Blanca, Peru). All altitudinal transects cover a wide range of natural ecosystems under different climates and soil geochemistry. Bulk soil samples (four field replicates per ecosystem) were subjected to a combination of aggregate and particle-size fractionation followed by organic C, total nitrogen, stable isotope (13C, 15N) and radiocarbon (14C) analyses of all fractions. Bulk soils were further characterized for their geochemistry (Na, K, Ca, Mg, Al, Fe, Mn, Si, P) and incubated for 63 days to assess greenhouse gas emissions (CO2, CH4, NO, N2O). Further, stable C isotopic signature of CO2 was measured to determine the isotopic signature of soil respiration (using Keeling plots) and to estimate potential respiration sources. The following four ecosystems were sampled at an altitudinal transect on the (wet) southern slopes of Mount Kilimanjaro: savannah (920m), lower montane rain forests with angiosperm trees (2020m), upper montane cloud forest with gymnosperm trees (2680m), subalpine heathlands (3660m). Both forests showed highest C contents followed by subalpine and savannah. The largest part of SOC was found in particulate organic matter followed by microaggregates, except for the subalpine ecosystem which had most SOC stored in microaggregates. Silt and clay fractions stored the smallest fraction of SOC for all ecosystems. Cumulative soil CO2 emissions (normalized to SOC, gCO_2-C kgSOC-1) after 63 days of incubation were highest for savannah (15.2 ± 1.4) followed by subalpine (7.9 ± 0.5), upper forest (6.9 ± 1.0) and lower forest (4.8 ± 0.4). CO2 emissions were negatively correlated with soil C contents, showing that soils with lower C contents loose higher relative amounts of their SOC through soil respiration. Keeling plot intercept is a measure for the isotopic signature of respired CO2 and high offsets between Keeling plot intercepts and the isotopic signature of bulk SOC point towards labile (13C-depleted) SOC fractions as respiration sources. Highest offsets (and thus most labile respiration sources) were observed for savannah followed by subalpine, lower forest and upper forest and these were positively correlated with cumulative CO2 emissions, showing that in savannah soils, which have lowest C contents and respire highest amounts of CO2, mainly labile SOC is used as respiration source. Results from the other two altitudinal transects are currently under investigation and will be presented in conjunction with climatic and geochemical data.

Biodiversity of seagrass bed in Balanan Resort - Baluran National Park

NASA Astrophysics Data System (ADS)

Soedarti, T.; Hariyanto, S.; Wedayanti, A.; Rahmawati, A. D.; Safitri, D. P.; Alificia, R. I.; Suwono

2017-09-01

Seagrass beds are flowering plants that live on the seabed. Seagrass provides a habitat for diverse flora and fauna, spawning ground, nursery ground, raising ground, and feeding ground. Balanan Resort - Baluran National Park has many beaches, such as Kajang Beach, Si Banjir Beach, Kakapa Beach, and Serondo Beach. This study was aimed to determine species composition, seagrass dominated, and the diversity index of seagrass and substrate in Resort Balanan - Baluran National Park. This research was carried out in Kajang Beach, Sibanjir Beach, Kakapa Beach, and Sirondo Beach from August to September 2015 using belt transect method, each transect consists of 15 plots (19 transects = 285 plots) and using the frame of 1x1 m. This research found seven genera and ten species : Cymodoce (C rotundata and C. serrulata), Syringodium (S. isoelifolium), Thallassodendron (T. ciliatum), Enhalus (E. acoroides) , Halodule (H. univernis and H. pinifolia), Halophila (H. ovalis and H. decipiens), and Thalassia (T. hemprichii). The diversity index of seagrass bed was moderate [H'=1.90] in Balanan Resort. The substrate of seagrass bed was mud, gravel, sand, clay sand and rubble in Balanan Resort. The dominance index was near zero [C = 0.194], that means no dominant species.

Biodiversity Measurement Using Indices Based on Hyperspectral Reflectance on the Coast of Lagos

NASA Astrophysics Data System (ADS)

Omodanisi, E. O.; Salami, A. T.

2013-12-01

Hyperspectral measurements provide explicit measurements which can be used in the analysis of biodiversity change. This study was carried out in the coastal area of Lagos State, Nigeria. The objective of this study was to determine if gasoline seepage affects vegetation species distribution and reflectance; with the view to analyzing the vegetation condition. To evaluate the potential of different reflectance spectroscopy of species, the ASD Handheld2 Spectrometer was used. Three identified impacted plots of 30m by 30m were selected randomly and a control plot established in relatively undisturbed vegetated areas away from but perpendicular to the source of seepage. Each identified plot and the control consisted of five transects and measurement were taken at every 2m with about four reflectance measurement per sample point, to average out differences in reflectance as a result of different leaf angles. The radiance output of the spectrometer was converted into reflectance using the reflectance of a white reference over a standardized white spectralon panel. Indices such as Normalized Differential Vegetation Index, RedEdge Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index, Ratio Vegetation Index and Volgelmann RedEdge Index 1 were calculated to accurately estimate the chlorophyll content in the vegetation within optimal band wavelength. Shannon-Weiner's index, Spearman's rank correlation and Analysis of Variance were used to analyze the data. Cocos nucifera was observed to be the most dominant species with a relative abundance of 47.27% while Ananas comosus recorded the lowest relative abundance of 21.8%. In the control plot, Cocos nucifera had the highest relative abundance of 42.3% and Mangifera indica with the least relative abundance of 16.7%. The relationship between the indices and chlorophyll content of the vegetation were significantly higher at (p>0.01) for all the indices in all the plots; however, RedEdgeNDVI and VOG1 indices had the highest occurring frequency among the entire plots. Thus they were used to distinguish relatively healthy from relatively unhealthy vegetation and it was statistically higher at F-ratio 4.825 (p<0.01) and 3.194 (p<0.01) respectively. It was concluded that gasoline affected the condition of vegetation.Table 2: Spearman's rank correlation analysis for relating indices with chlorophyll content for the field data at p>0.01, rho - correlation coefficient. (Source: Author: 2012) Field Spectral Indices Measurement The measurement above is the averaged value for the entire transect in each plot.(Source: Author, 2012)

The effect of climate and soil conditions on tree species turnover in a Tropical Montane Cloud Forest in Costa Rica.

PubMed

Häger, Achim

2010-12-01

On a global level, Tropical Montane Cloud Forests constitute important centers of vascular plant diversity. Tree species turnover along environmental gradients plays an important role in larger scale diversity patterns in tropical mountains. This study aims to estimate the magnitude of beta diversity across the Tilardn mountain range in North-Western Costa Rica, and to elucidate the impact of climate and soil conditions on tree species turnover at a local scale. Seven climate stations measuring rainfall, horizontal precipitation (clouds and wind-driven rain) and temperatures were installed along a 2.5km transect ranging from 1200 m.a.s.l. on the Atlantic to 1200 m.a.s.l. on the Pacific slope. The ridge top climate station was located at 1500 m.a.s.l. Climate data were recorded from March through December 2003. Additionally, seven 0.05 ha plots were established. On all plots soil moisture was monitored for one year, furthermore soil type and soil chemistry were assessed. Woody plants with a diameter at breast height (dbh) > or = 5 cm were identified to species. Species' distributions were explored by feeding pairwise Serensen measures between plots into a Principal Component Analysis. Relationships between floristic similarity and environmental variables were analyzed using Mantel tests. Pronounced gradients in horizontal precipitation, temperatures and soil conditions were found across the transect. In total, 483 woody plants were identified, belonging to 132 species. Environmental gradients were paralleled by tree species turnover; the plots could be divided in three distinctive floristic units which reflected different topographic positions on the transect (lower slopes, mid slopes and ridge). Most notably there was a complete species turnover between the ridge and the lower Pacific slope. Floristic similarity was negatively correlated with differences in elevation, horizontal precipitation, temperatures and soil conditions between plots. It is suggested that beta-diversity in the study area is largely driven by species with narrow spatial ranges, due to the interactions between topography, climate and soil formation processes, especially around the wind-exposed and cloud covered ridge area. The findings emphasize the extraordinary conservation value of tropical montane cloud forests in environmentally heterogeneous areas at mid-elevations.

[Sampling optimization for tropical invertebrates: an example using dung beetles (Coleoptera: Scarabaeinae) in Venezuela].

PubMed

Ferrer-Paris, José Rafael; Sánchez-Mercado, Ada; Rodríguez, Jon Paul

2013-03-01

The development of efficient sampling protocols is an essential prerequisite to evaluate and identify priority conservation areas. There are f ew protocols for fauna inventory and monitoring in wide geographical scales for the tropics, where the complexity of communities and high biodiversity levels, make the implementation of efficient protocols more difficult. We proposed here a simple strategy to optimize the capture of dung beetles, applied to sampling with baited traps and generalizable to other sampling methods. We analyzed data from eight transects sampled between 2006-2008 withthe aim to develop an uniform sampling design, that allows to confidently estimate species richness, abundance and composition at wide geographical scales. We examined four characteristics of any sampling design that affect the effectiveness of the sampling effort: the number of traps, sampling duration, type and proportion of bait, and spatial arrangement of the traps along transects. We used species accumulation curves, rank-abundance plots, indicator species analysis, and multivariate correlograms. We captured 40 337 individuals (115 species/morphospecies of 23 genera). Most species were attracted by both dung and carrion, but two thirds had greater relative abundance in traps baited with human dung. Different aspects of the sampling design influenced each diversity attribute in different ways. To obtain reliable richness estimates, the number of traps was the most important aspect. Accurate abundance estimates were obtained when the sampling period was increased, while the spatial arrangement of traps was determinant to capture the species composition pattern. An optimum sampling strategy for accurate estimates of richness, abundance and diversity should: (1) set 50-70 traps to maximize the number of species detected, (2) get samples during 48-72 hours and set trap groups along the transect to reliably estimate species abundance, (3) set traps in groups of at least 10 traps to suitably record the local species composition, and (4) separate trap groups by a distance greater than 5-10km to avoid spatial autocorrelation. For the evaluation of other sampling protocols we recommend to, first, identify the elements of sampling design that could affect the sampled effort (the number of traps, sampling duration, type and proportion of bait) and their spatial distribution (spatial arrangement of the traps) and then, to evaluate how they affect richness, abundance and species composition estimates.

Sampling animal sign in heterogeneous environments: how much is enough?

USGS Publications Warehouse

Holbrook, Joseph D.; Arkle, Robert S.; Rachlow, Janet L.; Vierling, Kerri T.; Pilliod, David S.

2015-01-01

Animal ecologists often use animal sign as a surrogate for direct observation of organisms, especially when species are secretive or difficult to observe. Spatial heterogeneity in arid environments makes it challenging to consistently detect and precisely characterize animal sign, which can bias estimates of animal abundance or habitat use. Piute ground squirrels (Urocitellus mollis) and Owyhee harvester ants (Pogonomyrmex salinus) live in arid environments and are fossorial, which can make them difficult to observe directly. Their relative abundance can be assessed using sign (i.e., burrows and nests). We implemented an over-sampling framework (i.e., recorded an excessive amount of information) with two observers to 1) identify a sampling intensity that balanced precision with our resource constraints, and 2) assess classification and detection of squirrel burrows and ant nests across vegetation conditions. We sampled 20 1-ha plots for ground squirrel burrows and ant nests using six 4 m × 100 m belt transects. Analyses of precision and sampling effort indicated that three belt transects covering 1200 m2 per ha provided sufficient precision, while minimizing effort. Regardless of vegetation conditions, counts by two observers were strongly correlated for ground squirrel burrows (r = 0.99, P < 0.001, df = 18; slope = 0.92) and harvester ant nests (r = 0.99, P < 0.001, df = 18; slope = 1.01) indicating observer consistency and perhaps high detection probability. These findings illustrate an approach for evaluating sampling designs in many ecological contexts.

Climate-driven speedup of alpine treeline forest growth in the Tianshan Mountains, Northwestern China.

PubMed

Qi, Zhaohuan; Liu, Hongyan; Wu, Xiuchen; Hao, Qian

2015-02-01

Forest growth is sensitive to interannual climatic change in the alpine treeline ecotone (ATE). Whether the alpine treeline ecotone shares a similar pattern of forest growth with lower elevational closed forest belt (CFB) under changing climate remains unclear. Here, we reported an unprecedented acceleration of Picea schrenkiana forest growth since 1960s in the ATE of Tianshan Mountains, northwestern China by a stand-total sampling along six altitudinal transects with three plots in each transect: one from the ATE between the treeline and the forest line, and the other two from the CFB. All the sampled P. schrenkiana forest patches show a higher growth speed after 1960 and, comparatively, forest growth in the CFB has sped up much slower than that in the ATE. The speedup of forest growth at the ATE is mainly accounted for by climate factors, with increasing temperature suggested to be the primary driver. Stronger water deficit as well as more competition within the CFB might have restricted forest growth there more than that within the ATE, implying biotic factors were also significant for the accelerated forest growth in the ATE, which should be excluded from simulations and predictions of warming-induced treeline dynamics. © 2014 John Wiley & Sons Ltd.

Line intersect sampling: Ell-shaped transects and multiple intersections

Treesearch

Timothy G. Gregoire; Harry T. Valentine

2003-01-01

The probability of selecting a population element under line intersect sampling depends on the width of the particle in the direction perpendicular to the transect, as is well known. The consequence of this when using ell-shaped transects rather than straight-line transects are explicated, and modifications that preserve design-unbiasedness of Kaiser's (1983)...

Plant community composition and vegetation height, Barrow, Alaska, Ver. 1

DOE Data Explorer

Siegrist, Julia; Norby, Richard; Sloan, Victoria; Iversen, Colleen; Brooks, Jonathan; Liebig, Jennifer; Wood, Sarah

2014-04-25

This dataset contains i) the results of field surveys of plant community composition and vegetation height made between 17th and 29th July 2012 in 48, 1 x 1 m plots located in areas A-D of Intensive Site 1 at the Next-Generation Ecosystem Experiments (NGEE) Arctic site near Barrow, Alaska and ii) results of a mapping exercise undertaken in August 2013 using two perpendicular transects across each polygon containing vegetation plots to determine the boundaries of vegetation communities described in 2012.

Determining Optimal Location and Numbers of Sample Transects for Characterization of UXO Sites

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

BILISOLY, ROGER L.; MCKENNA, SEAN A.

2003-01-01

Previous work on sample design has been focused on constructing designs for samples taken at point locations. Significantly less work has been done on sample design for data collected along transects. A review of approaches to point and transect sampling design shows that transects can be considered as a sequential set of point samples. Any two sampling designs can be compared through using each one to predict the value of the quantity being measured on a fixed reference grid. The quality of a design is quantified in two ways: computing either the sum or the product of the eigenvalues ofmore » the variance matrix of the prediction error. An important aspect of this analysis is that the reduction of the mean prediction error variance (MPEV) can be calculated for any proposed sample design, including one with straight and/or meandering transects, prior to taking those samples. This reduction in variance can be used as a ''stopping rule'' to determine when enough transect sampling has been completed on the site. Two approaches for the optimization of the transect locations are presented. The first minimizes the sum of the eigenvalues of the predictive error, and the second minimizes the product of these eigenvalues. Simulated annealing is used to identify transect locations that meet either of these objectives. This algorithm is applied to a hypothetical site to determine the optimal locations of two iterations of meandering transects given a previously existing straight transect. The MPEV calculation is also used on both a hypothetical site and on data collected at the Isleta Pueblo to evaluate its potential as a stopping rule. Results show that three or four rounds of systematic sampling with straight parallel transects covering 30 percent or less of the site, can reduce the initial MPEV by as much as 90 percent. The amount of reduction in MPEV can be used as a stopping rule, but the relationship between MPEV and the results of excavation versus no-further-action decisions is site specific and cannot be calculated prior to the sampling. It may be advantageous to use the reduction in MPEV as a stopping rule for systematic sampling across the site that can then be followed by focused sampling in areas identified has having UXO during the systematic sampling. The techniques presented here provide answers to the questions of ''Where to sample?'' and ''When to stop?'' and are capable of running in near real time to support iterative site characterization campaigns.« less

Characterizing 2-D snow stratigraphy in forests based on high-resolution snow penetrometry

NASA Astrophysics Data System (ADS)

Teich, M.; Loewe, H.; Jenkins, M. J.; Schneebeli, M.

2016-12-01

Snow stratigraphy, the characteristic layering within a seasonal snowpack, has important implications for snow remote sensing, hydrology and avalanches. Forests modify snowpack properties through interception of falling snow by tree crowns, the reduction of near-surface wind speeds, and changes to the energy balance beneath and around trees leading to a highly variable stratigraphy in space and time. The lack of snowpack observations in forests limits our ability to understand the spatio-temporal evolution of snow stratigraphy as a function of forest structure and to observe snowpack response to changes in forest cover. We examined the snowpack in field campaigns using the SnowMicroPen (SMP) under tree canopies in an Engelmann spruce forest in the central Rocky Mountains in Utah, USA. Data were collected in plots beneath canopies of undisturbed, bark beetle-disturbed and salvage logged forest stands, and a non-forested meadow. In 2015 weekly-repeated SMP penetration measurements were taken along 10 m transects at 0.3 m intervals. In the winter of 2016 bi-weekly measurements were collected along 20 m transects every 0.5 m. Using a statistical model, we derived 2-D snow density profiles as a measure of stratigraphy. The small-scale patterns in snow density revealed a more heterogeneous stratigraphy in undisturbed dense stands and also beneath bark beetle-disturbed forest. In contrast, snow stratigraphy was more homogeneous in the harvested plot despite standing small diameter trees and woody debris with effective heights up to 95 cm. As expected, snow depth and layering in non-forested plots varied only slightly over the small spatial extent sampled. Observed patterns changed throughout the snow season dependent upon snow and meteorological conditions. The results contribute to the general understanding of forest-snowpack interactions at high spatial resolution, and can be used to validate snowpack and microwave models for avalanche formation processes and SWE retrieval in forests.

Vegetation analysis for arid lands geobotany

NASA Technical Reports Server (NTRS)

Barbour, M. G.; Ustin, S. L.

1985-01-01

Three primary study sites were selected for measurement of plant phenological properties and spectral analysis. The sites selected represented typical sagebrush, creosote bush, and saltbush communities in Owens Valley, CA. Community composition was studied at these three sites plus five burned sites. Ten 50 m transects at each locality were measured for percent cover (over 10 cm) by a given species. On each transect two point quarter and five nearest neighbor analyses were conducted. These data provided percent cover, cover by area, plant size, tendency for association, and recolonization patterns after a disturbance. Plots representing percentage plant cover for six sites are included.

TRANSECT STUDY OF THE INTRINSIC BIOREMEDIATION TEST PLOT: DOVER AFB

EPA Science Inventory

The work described in this report is part of a project undertaken by the Bioremediation of Chlorinated Solvents Action Team of the Remediation Technologies Development Forum, a joint U.S. Federal agency-industry collaboration, to study the natural attenuation of chlorinated ethen...

Correction of bias in belt transect studies of immotile objects

USGS Publications Warehouse

Anderson, D.R.; Pospahala, R.S.

1970-01-01

Unless a correction is made, population estimates derived from a sample of belt transects will be biased if a fraction of, the individuals on the sample transects are not counted. An approach, useful for correcting this bias when sampling immotile populations using transects of a fixed width, is presented. The method assumes that a searcher's ability to find objects near the center of the transect is nearly perfect. The method utilizes a mathematical equation, estimated from the data, to represent the searcher's inability to find all objects at increasing distances from the center of the transect. An example of the analysis of data, formation of the equation, and application is presented using waterfowl nesting data collected in Colorado.

Design unbiased estimation in line intersect sampling using segmented transects

Treesearch

David L.R. Affleck; Timothy G. Gregoire; Harry T. Valentine; Harry T. Valentine

2005-01-01

In many applications of line intersect sampling. transects consist of multiple, connected segments in a prescribed configuration. The relationship between the transect configuration and the selection probability of a population element is illustrated and a consistent sampling protocol, applicable to populations composed of arbitrarily shaped elements, is proposed. It...

Transformations of the chemical compositions of high molecular weight DOM along a salinity transect: Using two dimensional correlation spectroscopy and principal component analysis approaches

NASA Astrophysics Data System (ADS)

Abdulla, Hussain A. N.; Minor, Elizabeth C.; Dias, Robert F.; Hatcher, Patrick G.

2013-10-01

In a study of chemical transformations of estuarine high-molecular-weight (HMW, >1000 Da) dissolved organic matter (DOM) collected over a period of two years along a transect through the Elizabeth River/Chesapeake Bay system to the coastal Atlantic Ocean off Virginia, USA, δ13C values, N/C ratios, and principal component analysis (PCA) of the solid-state 13C NMR (nuclear magnetic resonance) spectra of HMW-DOM show an abrupt change in both its sources and chemical structural composition occurring around salinity 20. HMW-DOM in the lower salinity region had lighter isotopic values, higher aromatic and lower carbohydrate contents relative to that in the higher salinity region. These changes around a salinity of 20 are possibly due to introduction of a significant amount of new carbon (autotrophic DOM) to the transect. PC-1 loadings plot shows that spatially differing DOM components are similar to previously reported 13C NMR spectra of heteropolysaccharides (HPS) and carboxyl-rich alicyclic molecules (CRAM). Applying two dimensional correlation spectroscopy techniques to 1H NMR spectra from the same samples reveals increases in the contribution of N-acetyl amino sugars, 6-deoxy sugars, and sulfated polysaccharides to HPS components along the salinity transect, which suggests a transition from plant derived carbohydrates to marine produced carbohydrates within the HMW-DOM pool. In contrast to what has been suggested previously, our combined results from 13C NMR, 1H NMR, and FTIR indicate that CRAM consists of at least two different classes of compounds (aliphatic polycarboxyl compounds and lignin-like compounds).

Dynamic enhancement MRI of anterior lobe in pituitary dwarfism.

PubMed

Liu, H M; Li, Y W; Tsai, W Y; Su, C T

1995-08-01

We examined 23 patients with pituitary dwarfism by dynamic MRI; with a repetition time of 150 or 50 ms. The time-enhancement difference curves of selected regions in the anterior lobes were plotted. Another 48 patients with no definite clinical pituitary disfunction were examined with the same technique. We found that the intensity of maximum enhancement in both groups was similar, but the time to achieve maximum enhancement was delayed in pituitary dwarfism with or without stalk transection; the time seemed longest with stalk transection. There was little difference in enhancement between patients with multiple hormone deficiency or isolated growth hormone deficiency. Dynamic MRI of the anterior lobes may be an important functional imaging study, and our results imply that poor perfusion is a useful finding in pituitary dwarfism, especially in patients without stalk transection and normal pituitary height.

Comparison of point intercept and image analysis for monitoring rangeland transects

USDA-ARS?s Scientific Manuscript database

Amidst increasing workloads and static or declining budgets, both public and private land management agencies face the need to adapt resource-monitoring techniques or risk falling behind on resource monitoring volume and quality with old techniques. Image analysis of nadir plot images, acquired with...

The impact of forest roads on understory plant diversity in temperate hornbeam-beech forests of Northern Iran.

PubMed

Deljouei, Azade; Abdi, Ehsan; Marcantonio, Matteo; Majnounian, Baris; Amici, Valerio; Sohrabi, Hormoz

2017-08-01

Forest roads alter the biotic and abiotic components of ecosystems, modifying temperature, humidity, wind speed, and light availability that, in turn, cause changes in plant community composition and diversity. We aim at investigating and comparing the diversity of herbaceous species along main and secondary forest roads in a temperate-managed hornbeam-beech forest, north of Iran. Sixteen transects along main and secondary forest roads were established (eight transects along main roads and eight along secondary roads). To eliminate the effect of forest type, all transects were located in Carpinetum-Fagetum forests, the dominant forest type in the study area. The total length of each transect was 200 m (100 m toward up slope and 100 m toward down slope), and plots were established along it at different distances from road edge. The diversity of herbaceous plant species was calculated in each plot using Shannon-Wiener index, species richness, and Pielou's index. The results showed that diversity index decreased when distance from road edge increases. This decreasing trend continued up to 60 m from forest road margin, and after this threshold, the index slightly increased. Depending on the type of road (main or secondary) as well as cut or fill slopes, the area showing a statistical different plant composition and diversity measured through Shannon-Wiener, species richness, and Pielou's index is up to 10 m. The length depth of the road edge effect found in main and secondary forest roads was small, but it could have cumulative effects on forest microclimate and forest-associated biota at the island scale. Forest managers should account for the effect of road buildings on plant communities.

Evaluating rapid ground sampling and scaling estimated plant cover using UAV imagery up to Landsat for mapping arctic vegetation

NASA Astrophysics Data System (ADS)

Nelson, P.; Paradis, D. P.

2017-12-01

The small stature and spectral diversity of arctic plant taxa presents challenges in mapping arctic vegetation. Mapping vegetation at the appropriate scale is needed to visualize effects of disturbance, directional vegetation change or mapping of specific plant groups for other applications (eg. habitat mapping). Fine spatial grain of remotely sensed data (ca. 10 cm pixels) is often necessary to resolve patches of many arctic plant groups, such as bryophytes and lichens. These groups are also spectrally different from mineral, litter and vascular plants. We sought to explore method to generate high-resolution spatial and spectral data to explore better mapping methods for arctic vegetation. We sampled ground vegetation at seven sites north or west of tree-line in Alaska, four north of Fairbanks and three northwest of Bethel, respectively. At each site, we estimated cover of plant functional types in 1m2 quadrats spaced approximately every 10 m along a 100 m long transect. Each quadrat was also scanned using a field spectroradiometer (PSR+ Spectral Evolution, 400-2500 nm range) and photographed from multiple perspectives. We then flew our small UAV with a RGB camera over the transect and at least 50 m on either side collecting on imagery of the plot, which were used to generate a image mosaic and digital surface model of the plot. We compare plant functional group cover ocular estimated in situ to post-hoc estimation, either automated or using a human observer, using the quadrat photos. We also compare interpolated lichen cover from UAV scenes to estimated lichen cover using a statistical models using Landsat data, with focus on lichens. Light and yellow lichens are discernable in the UAV imagery but certain lichens, especially dark colored lichens or those with spectral signatures similar to graminoid litter, present challenges. Future efforts will focus on integrating UAV-upscaled ground cover estimates to hyperspectral sensors (eg. AVIRIS ng) for better combined spectral and spatial resolution.

Field suppression of the invasive ant Wasmannia auropunctata (Hymenoptera: Formicidae) in a tropical fruit orchard in Hawaii.

PubMed

Souza, Evann; Follett, Peter A; Price, Don K; Stacy, Elizabeth A

2008-08-01

The little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), is an invasive ant that forms supercolonies when it successfully invades new areas. W. auropunctata was first reported in Hawaii in 1999, and it has since invaded a variety of agricultural sites, including nurseries, orchards, and pastures. Amdro (hydramethylnon; in bait stations), Esteem (pyriproxyfen; broadcast bait), and Conserve (spinosad; ground spray) were tested for their efficacy against W. auropunctata in a rambutan, Nephelium lappaceum L. and mangosteen, Garcinia mangostana L., orchard by making treatments every 2 wk for 16 wk. Relative estimates of ant numbers in plots was determined by transect sampling using peanut butter-baited sticks. Significant treatment effects were observed on weeks 13-17, with reductions in ant counts occurring in the Amdro and Esteem treatments. During this period, the reduction in ant numbers from pretreatment counts averaged 47.1 and 92.5% in the Amdro and Esteem plots, respectively, whereas ant numbers in the untreated control plots increased by 185.9% compared with pretreatment counts. Conserve did not cause a reduction in ant counts as applied in our experiment. No plots for any of the treatments achieved 100% reduction. Pseudococcidae were counted on branch terminals at 4-wk intervals. The two predominant species, Nipaecoccus nipae (Maskell) and Nipaecoccus viridis (Newstead) were significantly lower in the Amdro and Esteem treatments on week 16 compared with controls. Many W. auropunctata were found nesting in protected sites in the orchard trees, which may have compromised the ground-based control methods. Absolute density estimates from shallow core samples taken from the orchard floor indicated the W. auropunctata supercolony exceeded 244 million ants and 22.7 kg wet weight per ha.

In-Situ Hydraulic Conductivities of Soils and Anomalies at a Future Biofuel Production Site

NASA Astrophysics Data System (ADS)

Williamson, M. F.; Jackson, C. R.; Hale, J. C.; Sletten, H. R.

2010-12-01

Forested hillslopes of the Upper Coastal Plain at the Savannah River Site, SC, feature a shallow clay loam argillic layer with low median saturated hydraulic conductivity. Observations from a grid of shallow, maximum-rise piezometers indicate that perching on this clay layer is common. However, flow measurements from an interflow-interception trench indicate that lateral flow is rare and most soil water percolates through the clay layer. We hypothesize that the lack of frequent lateral flow is due to penetration of the clay layer by roots of pine trees. We used ground penetrating radar (GPR) to map the soil structure and potential anomalies, such as root holes, down to two meters depth at three 10×10-m plots. At each plot, a 1×10-m trench was later back-hoe excavated along a transect that showed the most anomalies on the GPR maps. Each trench was excavated at 0.5-m intervals until the clay layer was reached (two plots were excavated to a final depth of 0.875 m and the third plot was excavated to a final depth of 1.0 m). At each interval, compact constant-head permeameters (CCHPs) were used to measure in-situ hydraulic conductivities in the clay-loam matrix and in any visually apparent anomalies. Conductivity was also estimated using a second 1×10-m transect of CCHP measurements taken within randomly placed augur holes. Additional holes targeted GPR anomalies. The second transect was created in case the back-hoe impacted conductivity readings. High-conductivity anomalies were also visually investigated by excavating with a shovel. Photographs of soil wetness were taken at visually apparent anomalies with a multispectral camera. We discovered that all visually apparent anomalies found are represented on the GPR maps, but that not all of the predicted anomalies on the GPR maps are visually apparent. We discovered that tree root holes create anomalies, but that there were also many conductivity anomalies that could not be visually distinguished from low-conductivity soil.

Welfare assessment in broiler farms: transect walks versus individual scoring.

PubMed

Marchewka, J; Watanabe, T T N; Ferrante, V; Estevez, I

2013-10-01

Current scientific approaches to welfare assessment in broilers are based on individual sampling that can be time consuming under field conditions. On the other hand, farmers conduct routine checks based on walks through the house to screen birds' health condition. We adapted the walks through following line transect methodology used in wildlife studies to explore their feasibility as a welfare assessment tool. The aim of this study was to compare broiler welfare assessed by individual sampling and transect walks. We evaluated 6 identically managed flocks. For individual sampling, we collected measures on 150 birds, including weight, breast dirtiness, hock and footpad dermatitis, lameness, and immobility. Transect observations were conducted by slowly walking on randomized paths within each house recording: immobility, lameness, back dirtiness, sickness, agony, and dead. Transect walks allowed detection of small variations (P < 0.003) in the prevalence of most welfare indicators considered with consistency in interobserver reliability (P ≥ 0.05). In addition, assessments across transects were highly consistent (P ≥ 0.05). Individual sampling was also sensitive to differences across houses (P < 0.01) with the exception of immobility (P = 0.783). No differences were found across sampling locations (P ≥ 0.05). However, both methods differed greatly in the frequency of the incidence of the parameters considered. For example, immobility varied from 0.2 ± 0.02% for transect walks to 4 ± 2.3% for individual sampling, whereas lameness varied between 0.8 ± 0.07% and 24.2 ± 4.7% for transect and samplings, respectively. It is possible that the transect approach may have overlooked walking deficiencies because a large number of birds were scored, although if this was the case, the consistency obtained in the scoring across observers and transects would be surprising. Differences may also be related to possibly biased individual sampling procedures, where less mobile and passive individuals may be more likely to be caught. Furthermore the procedure may cause fatigue and fear reactions reducing mobility. Current study provides new insights into constraints and advantages of broiler on-farm assessment methods, which should be considered for designing on-farm welfare assessment protocols.

Ecosystem services from keystone species: diversionary seeding and seed-caching desert rodents can enhance Indian ricegrass seedling establishment

USGS Publications Warehouse

Longland, William; Ostoja, Steven M.

2013-01-01

Seeds of Indian ricegrass (Achnatherum hymenoides), a native bunchgrass common to sandy soils on arid western rangelands, are naturally dispersed by seed-caching rodent species, particularly Dipodomys spp. (kangaroo rats). These animals cache large quantities of seeds when mature seeds are available on or beneath plants and recover most of their caches for consumption during the remainder of the year. Unrecovered seeds in caches account for the vast majority of Indian ricegrass seedling recruitment. We applied three different densities of white millet (Panicum miliaceum) seeds as “diversionary foods” to plots at three Great Basin study sites in an attempt to reduce rodents' over-winter cache recovery so that more Indian ricegrass seeds would remain in soil seedbanks and potentially establish new seedlings. One year after diversionary seed application, a moderate level of Indian ricegrass seedling recruitment occurred at two of our study sites in western Nevada, although there was no recruitment at the third site in eastern California. At both Nevada sites, the number of Indian ricegrass seedlings sampled along transects was significantly greater on all plots treated with diversionary seeds than on non-seeded control plots. However, the density of diversionary seeds applied to plots had a marginally non-significant effect on seedling recruitment, and it was not correlated with recruitment patterns among plots. Results suggest that application of a diversionary seed type that is preferred by seed-caching rodents provides a promising passive restoration strategy for target plant species that are dispersed by these rodents.

Long-term population monitoring: Lessons learned from an endangered passerine in Hawai‘i

USGS Publications Warehouse

Johnson, Luanne; Camp, Richard J.; Brinck, Kevin W.; Banko, Paul C.

2006-01-01

Obtaining reliable population estimates is crucial to monitoring endangered species and developing recovery strategies. The palila (Loxioides bailleui) is an endangered seed-eating Hawaiian honeycreeper restricted to the subalpine forests of Mauna Kea, a volcano on the island of Hawai‘i, USA. The species is vulnerable to extinction primarily because >90% of the population is concentrated in <30 km2 of habitat on the western slope of this high, dormant volcano. Annual surveys of the palila population have been conducted for ecological, legal, and other purposes since 1980. Because refinements to sampling protocols and analytical methods have evolved, we examined means of adapting the monitoring program to produce comparable estimates of abundance over the past 25-year period and into the future. We conducted variable circular plot surveys during the nonbreeding season (Jan–Mar) and this used data to obtain estimates of effective detection radius and annual density with Distance 4.0, Release 2. For comparability over the time-series, we excluded from analysis the data from new transects. We partitioned the 25-year data set (1980–1996 and 1997–2004) into 2 separate analyses because, beginning in 1997, observers received more training to reduce their tendency to estimate distances to 5-m intervals. We used geographic strata in the analysis of recent surveys because changes in habitat may have invalidated the density-based strata used previously. By adding observer and year and observer and time of day as co-variables, we improved the model fit to the 2 data sets, respectively. Annual estimates were confounded by changes in sampling methodology and analytical procedures over time. However, the addition of new transects, increased training for observers, and use of exact distance estimates instead of rounding also improved model fit. Habitat characteristics and behavior of palila that potentially influenced detection probability, sampling, analysis, and interpretation were regeneration of trees in response to reduced numbers of introduced browsing mammals, seasonally variable rates of vocalization, non-territoriality, and resource-tracking along an elevation gradient. We believe our adaptive approach to analysis and interpretation of 25 years of annual variable circular plot data could help guide similar long-term monitoring efforts.

Lead burdens and behavioral impairments of the lined shore crab Pachygrapsus crassipes

USGS Publications Warehouse

Hui, Clifford A.

2002-01-01

Unless a correction is made, population estimates derived from a sample of belt transects will be biased if a fraction of, the individuals on the sample transects are not counted. An approach, useful for correcting this bias when sampling immotile populations using transects of a fixed width, is presented. The method assumes that a searcher's ability to find objects near the center of the transect is nearly perfect. The method utilizes a mathematical equation, estimated from the data, to represent the searcher's inability to find all objects at increasing distances from the center of the transect. An example of the analysis of data, formation of the equation, and application is presented using waterfowl nesting data collected in Colorado.

Guided transect sampling - a new design combining prior information and field surveying

Treesearch

Anna Ringvall; Goran Stahl; Tomas Lamas

2000-01-01

Guided transect sampling is a two-stage sampling design in which prior information is used to guide the field survey in the second stage. In the first stage, broad strips are randomly selected and divided into grid-cells. For each cell a covariate value is estimated from remote sensing data, for example. The covariate is the basis for subsampling of a transect through...

Assessing relative abundance and reproductive success of shrubsteppe raptors

USGS Publications Warehouse

Lehman, Robert N.; Carpenter, L.B.; Steenhof, Karen; Kochert, Michael N.

1998-01-01

From 1991-1994, we quantified relative abundance and reproductive success of the Ferruginous Hawk (Buteo regalis), Northern Harrier (Circus cyaneus), Burrowing Owl (Speotytoc unicularia), and Short-eared Owl (Asio flammeus) on the shrubsteppe plateaus (benchlands) in and near the Snake River Birds of Prey National Conservation Area in southwestern Idaho. To assess relative abundance, we searched randomly selected plots using four sampling methods: point counts, line transects, and quadrats of two sizes. On a persampling-effort basis, transects were slightly more effective than point counts and quadrats for locating raptor nests (3.4 pairs detected/100 h of effort vs. 2.2-3.1 pairs). Random sampling using quadrats failed to detect a Short-eared Owl population increase from 1993 to 1994. To evaluate nesting success, we tried to determine reproductive outcome for all nesting attempts located during random, historical, and incidental nest searches. We compared nesting success estimates based on all nesting attempts, on attempts found during incubation, and the Mayfield model. Most pairs used to evaluate success were pairs found incidentally. Visits to historical nesting areas yielded the highest number of pairs per sampling effort (14.6/100 h), but reoccupancy rates for most species decreased through time. Estimates based on all attempts had the highest sample sizes but probably overestimated success for all species except the Ferruginous Hawk. Estimates of success based on nesting attempts found during incubation had the lowest sample sizes. All three methods yielded biased nesting snccess estimates for the Northern Harrier and Short-eared Owl. The estimate based on pairs found during incubation probably provided the least biased estimate for the Burrowing Owl. Assessments of nesting success were hindered by difficulties in confirming egg laying and nesting success for all species except the Ferruginous hawk.

Spatial variability in cost and success of revegetation in a Wyoming big sagebrush community.

PubMed

Boyd, Chad S; Davies, Kirk W

2012-09-01

The ecological integrity of the Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle and A. Young) alliance is being severely interrupted by post-fire invasion of non-native annual grasses. To curtail this invasion, successful post-fire revegetation of perennial grasses is required. Environmental factors impacting post-fire restoration success vary across space within the Wyoming big sagebrush alliance; however, most restorative management practices are applied uniformly. Our objectives were to define probability of revegetation success over space using relevant soil-related environmental factors, use this information to model cost of successful revegetation and compare the importance of vegetation competition and soil factors to revegetation success. We studied a burned Wyoming big sagebrush landscape in southeast Oregon that was reseeded with perennial grasses. We collected soil and vegetation data at plots spaced at 30 m intervals along a 1.5 km transect in the first two years post-burn. Plots were classified as successful (>5 seedlings/m(2)) or unsuccessful based on density of seeded species. Using logistic regression we found that abundance of competing vegetation correctly predicted revegetation success on 51 % of plots, and soil-related variables correctly predicted revegetation performance on 82.4 % of plots. Revegetation estimates varied from $167.06 to $43,033.94/ha across the 1.5 km transect based on probability of success, but were more homogenous at larger scales. Our experimental protocol provides managers with a technique to identify important environmental drivers of restoration success and this process will be of value for spatially allocating logistical and capital expenditures in a variable restoration environment.

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.

An indigenous Pacific Island agroforestry system: Pohnpei Island

Treesearch

Bill Raynor; James Fownes

1993-01-01

The indigenous agroforestry system on Pohnpei was studied using circular plots laid out in transect across 57 randomly-selected farms. Data were collected on species and cultivar presence, size, density, frequency, as well as soil type, slope, aspect, and other related information. Through farmer interviews, farm family demographic data was also recorded. Seasonality...

Nutrient addition dramatically accelerates microbial community succession.

PubMed

Knelman, Joseph E; Schmidt, Steven K; Lynch, Ryan C; Darcy, John L; Castle, Sarah C; Cleveland, Cory C; Nemergut, Diana R

2014-01-01

The ecological mechanisms driving community succession are widely debated, particularly for microorganisms. While successional soil microbial communities are known to undergo predictable changes in structure concomitant with shifts in a variety of edaphic properties, the causal mechanisms underlying these patterns are poorly understood. Thus, to specifically isolate how nutrients--important drivers of plant succession--affect soil microbial succession, we established a full factorial nitrogen (N) and phosphorus (P) fertilization plot experiment in recently deglaciated (∼3 years since exposure), unvegetated soils of the Puca Glacier forefield in Southeastern Peru. We evaluated soil properties and examined bacterial community composition in plots before and one year after fertilization. Fertilized soils were then compared to samples from three reference successional transects representing advancing stages of soil development ranging from 5 years to 85 years since exposure. We found that a single application of +NP fertilizer caused the soil bacterial community structure of the three-year old soils to most resemble the 85-year old soils after one year. Despite differences in a variety of soil edaphic properties between fertilizer plots and late successional soils, bacterial community composition of +NP plots converged with late successional communities. Thus, our work suggests a mechanism for microbial succession whereby changes in resource availability drive shifts in community composition, supporting a role for nutrient colimitation in primary succession. These results suggest that nutrients alone, independent of other edaphic factors that change with succession, act as an important control over soil microbial community development, greatly accelerating the rate of succession.

Nutrient Addition Dramatically Accelerates Microbial Community Succession

PubMed Central

Knelman, Joseph E.; Schmidt, Steven K.; Lynch, Ryan C.; Darcy, John L.; Castle, Sarah C.; Cleveland, Cory C.; Nemergut, Diana R.

2014-01-01

The ecological mechanisms driving community succession are widely debated, particularly for microorganisms. While successional soil microbial communities are known to undergo predictable changes in structure concomitant with shifts in a variety of edaphic properties, the causal mechanisms underlying these patterns are poorly understood. Thus, to specifically isolate how nutrients – important drivers of plant succession – affect soil microbial succession, we established a full factorial nitrogen (N) and phosphorus (P) fertilization plot experiment in recently deglaciated (∼3 years since exposure), unvegetated soils of the Puca Glacier forefield in Southeastern Peru. We evaluated soil properties and examined bacterial community composition in plots before and one year after fertilization. Fertilized soils were then compared to samples from three reference successional transects representing advancing stages of soil development ranging from 5 years to 85 years since exposure. We found that a single application of +NP fertilizer caused the soil bacterial community structure of the three-year old soils to most resemble the 85-year old soils after one year. Despite differences in a variety of soil edaphic properties between fertilizer plots and late successional soils, bacterial community composition of +NP plots converged with late successional communities. Thus, our work suggests a mechanism for microbial succession whereby changes in resource availability drive shifts in community composition, supporting a role for nutrient colimitation in primary succession. These results suggest that nutrients alone, independent of other edaphic factors that change with succession, act as an important control over soil microbial community development, greatly accelerating the rate of succession. PMID:25050551

Sediment loads and transport at constructed chutes along the Missouri River - Upper Hamburg Chute near Nebraska City, Nebraska, and Kansas Chute near Peru, Nebraska

USGS Publications Warehouse

Densmore, Brenda K.; Rus, David L.; Moser, Matthew T.; Hall, Brent M.; Andersen, Michael J.

2016-02-04

Comparisons of concentrations and loads from EWI samples collected from different transects within a study site resulted in few significant differences, but comparisons are limited by small sample sizes and large within-transect variability. When comparing the Missouri River upstream transect to the chute inlet transect, similar results were determined in 2012 as were determined in 2008—the chute inlet affected the amount of sediment entering the chute from the main channel. In addition, the Kansas chute is potentially affecting the sediment concentration within the Missouri River main channel, but small sample size and construction activities within the chute limit the ability to fully understand either the effect of the chute in 2012 or the effect of the chute on the main channel during a year without construction. Finally, some differences in SSC were detected between the Missouri River upstream transects and the chute downstream transects; however, the effect of the chutes on the Missouri River main-channel sediment transport was difficult to isolate because of construction activities and sampling variability.

A New Sample Transect through the Sierra Madre Occidental Silicic Large Igneous Province in Southern Chihuahua State, Mexico: First Stratigraphic, Petrologic, and Geochemical Results

NASA Astrophysics Data System (ADS)

Andrews, G. D.; Davila Harris, P.; Brown, S. R.; Anderson, L.; Moreno, N.

2014-12-01

We completed a field sampling transect across the northern Sierra Madre Occidental silicic large igneous province (SMO) in December 2013. Here we present the first stratigraphic, petrological, and geochemical data from the transect between Hidalgo del Parral and Guadalupe y Calvo, Chihuahua, Mexico. This is the first new transect across the SMO in 25 years and the only one between existing NE - SW transects at Chihuahua - Hermosillo and Durango - Mazatlan. The 245 km-long transect along Mexican Highway 24 crosses the boundary between the extended (Basin and Range) and non-extended (Sierra Madre Occidental plateau) parts of the SMO, and allows sampling of previously undescribed Oligocene (?) - early Miocene (?) rhyolitic ignimbrites and lavas, and occasional post-rhyolite, Miocene (?) SCORBA basaltic andesite lavas. 54 samples of rhyolitic ignimbrites (40) and lavas (7), and basaltic andesite lavas (7) were sampled along the transect, including 8 canyon sections with more than one unit. The ignimbrites are overwhelming rhyodacitic (plagioclase and hornblende or biotite phyric) or rhyolitic (quartz (+/- sanidine) in additon to plagioclase and hornblende or biotite phyric) and sparsely to highly phyric. Preliminary petrographic (phenocryst abundances) and geochemical (major and trace element) will be presented and compared to existing data from elsewhere in the SMO. Future work will include U-Pb zircon dating and whole rock and in-zircon radiogenic isotopes analyses.

A parametric generalization of the Hayne estimator for line transect sampling

USGS Publications Warehouse

Burnham, Kenneth P.

1979-01-01

The Hayne model for line transect sampling is generalized by using an elliptical (rather than circular) flushing model for animal detection. By assuming the ration of major and minor axes lengths is constant for all animals, a model results which allows estimation of population density based directly upon sighting distances and sighting angles. The derived estimator of animal density is a generalization of the Hayne estimator for line transect sampling.

Strip transect sampling and analysis for avian habitat studies

Treesearch

Richard N. Conner; James G. Dickson

1980-01-01

Censusing procedures that detect effects of habitat treatment on birds are outlined. We suggest that only relative values of bird species diversity, equitability, abundance, and species richness need be obtained. We also suggest that 4, 250-m strip transects per treatment and 8-10 trips over each transect are adequate. Aspects of sampling design that affect within-...

Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin.

PubMed

Fernandes, Itanna O; de Souza, Jorge L P

2018-01-01

Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth's natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six plots (transects) each, totaling 30 sampling plots. The transects were distributed with 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, the study used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9,165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera and 324 species/morphospecies. The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna. Until recently, most studies conducted on hydroelectric plants, located in the Amazon Basin, were carried out after the implementation of dams in order to assess their impacts on the environment and biodiversity (Benchimol and Peres 2015, Latrubesse et al. 2017, Sá-Oliveira et al. 2015). Recent studies on dam impacts have begun to be conducted prior to dam implementation (e.g. Bobrowiec and Tavares 2017, Fraga et al. 2014, Moser et al. 2014), thus providing a better overview of the impact and a better assessment of its magnitude.

Forest development following mudflow deposition, Mount St. Helens, Washington

Treesearch

Marc H. Weber; Keith S. Hadley; Peter M. Frenzen; Jerry F. Franklin

2006-01-01

Volcanic mudflows are locally important disturbance agents in the Pacific Northwest rarely studied within the context of forest succession. We describe 18 years (1981–1999) of forest development on the Muddy River mudflow deposit following the 1980 eruption of Mount St. Helens using permanent plot data collected along two transects traversing the Cedar Flats river...

The preglacial sediment record of Lake Ladoga, NW Russia - first results from a multi-proxy study on a 23 m sediment record

NASA Astrophysics Data System (ADS)

Gromig, R.; Melles, M.; Wagner, B.; Krastel, S.; Andreev, A.; Fedorov, G.; Just, J.; Wennrich, V.; Savelieva, L.; Subetto, D.; Shumilovskikh, L.

2016-12-01

The joint German-Russian project 'PLOT - Paleolimnological Transect' aims to recover lake sediment sequences along a more than 6000 km long longitudinal transect across the Eurasian Arctic in order to study the Late Quaternary climatic and environmental history. The eastern end of the PLOT transect is formed by the well-studied record from Lake El'gygytgyn (NE Siberia). Lake Ladoga (N 60°50' E 31°30') is Europe's largest lake, both by size and volume and forms the westernmost end of the transect. Whereas modern sedimentation as well as the Holocene and Late Glacial history of Lake Ladoga have intensely been studied, the preglacial history of the lake is poorly studied to date by sediment cores drilled in the 1930's. A seismic survey of Lake Ladoga in summer 2013 revealed unconformities in the western lake basin, which may separate preglacial sediments in isolated depressions from Late Glacial and Holocene sediment successions above. A 23 m long sediment core (Co1309) was retrieved from one of these depressions. Core Co1309 was investigated by XRF-scanning, magnetic susceptibility measurements, as well as pollen, grain-size, and bio-geochemical analyses. An age-depth model combining radiocarbon, OSL, and paleomagnetic dates is in progress. Both, the pollen results and the OSL ages from the base of the record indicate a deposition during MIS 5e (Eemian). The well sorted reddish sands from this interval contain dinoflagellates suggesting at least brackish conditions, likely due to the existence of a gateway connecting a precursor of the Baltic Sea with the White Sea via Lake Ladoga. The Late Glacial sequence consists of greyish varved clays of decreasing thickness upwards with sporadically intercalated sand layers. The Holocene sequence is composed of brownish diatomaceous silty clay with minor proportions of sand.

The PLOT (Paleolimnological Transect) Project in the Russian Arctic

NASA Astrophysics Data System (ADS)

Gromig, R.; Andreev, A.; Baumer, M.; Bolshiyanov, D.; Fedorov, G.; Frolova, L.; Krastel, S.; Lebas, E.; Ludikova, A.; Melles, M.; Meyer, H.; Nazarova, L.; Pestryakova, L.; Savelieva, L.; Shumilovskikh, L.; Subetto, D.; Wagner, B.; Wennrich, V.

2017-12-01

The joint Russian- German project 'PLOT - Paleolimnological Transec' aims to recover lake sediment sequences along a >6000 km long longitudinal transect across the Eurasian Arctic in order to investigate the Late Quaternary climatic and environmental history. The climate history of the Arctic is of particular interest since it is the region, which is experiencing major impact of the current climate change. The project is funded for three years (2015-2018) by the Russian and German Ministries of Research. Since 2013 extensive fieldwork, including seismic surveys, coring, and hydrological investigations, was carried out at lakes Ladoga (NW Russia, pilot study), Bolshoye Shuchye (Polar Urals), Emanda (Verkhoyansk Range, field campaign planned for August 2017), Levinson-Lessing and Taymyr (Taymyr Peninsula). Fieldwork at lakes Bolshoye Shuchye, Levinson-Lessing and Taymyr was conducted in collaboration with the Russian-Norwegian CHASE (Climate History along the Arctic Seaboard of Eurasia) project. A major objective of the PLOT project was to recover preglacial sediments. A multiproxy approach was applied to the analytical work of all cores, including (bio-)geochemical, sedimentological, geophysical, and biological analyses. First data implies the presence of preglacial sediments in the cores from all lakes so far visited. Age-depth models, based on radiocarbon dating, OSL dating, paleomagnetic measurements, identification of cryptotephra, and varve counting (where applicable), are in progress. Climate variability in the records shall be compared to that recorded at Lake Eĺgygytgyn (NE Russia), which represents the master record for the Siberian Arctic. The outcome of the PLOT project will be a better understanding of the temporal and spatial variability and development of the Arctic climate. Here, we present the major results and first key interpretations of the PLOT project, along with an outlook on the future strategy and foci. First results from lakes Ladoga, Bolshoye Shuchye, Levinson-Lessing and Taymyr will be published in a special journal issue (Boreas) in spring 2018.

Can roads be used as transects for primate population surveys?.

PubMed

Hilário, Renato R; Rodrigues, Flávio H G; Chiarello, Adriano G; Mourthé, Italo

2012-01-01

Line transect distance sampling (LTDS) can be applied to either trails or roads. However, it is likely that sampling along roads might result in biased density estimates. In this paper, we compared the results obtained with LTDS applied on trails and roads for two primate species (Callithrix penicillata and Callicebus nigrifrons) to clarify whether roads are appropriate transects to estimate densities. We performed standard LTDS surveys in two nature reserves in south-eastern Brazil. Effective strip width and population density were different between trails and roads for C. penicillata, but not for C. nigrifrons. The results suggest that roads are not appropriate for use as transects in primate surveys, at least for some species. Further work is required to fully understand this issue, but in the meantime we recommend that researchers avoid using roads as transects or treat roads and trails as covariates when sampling on roads is unavoidable. Copyright © 2012 S. Karger AG, Basel.

Relative spatial soil geochemical variability along two transects across the United States and Canada

USGS Publications Warehouse

Garrett, Robert G.

2009-01-01

The patterns of relative variability differ by transect and horizon. The N–S transect A-horizon soils show significant between-40-km scale variability for 29 elements, with only 4 elements (Ca, Mg, Pb and Sr) showing in excess of 50% of their variability at the within-40-km and ‘at-site’ scales. In contrast, the C-horizon data demonstrate significant between-40-km scale variability for 26 elements, with 21 having in excess of 50% of their variability at the within-40-km and ‘at-site’ scales. In 36 instances, the ‘at-site’ variability is statistically significant in terms of the sample preparation and analysis variability. It is postulated that this contrast between the A- and C- horizons along the N–S transect, that is dominated by agricultural land uses, is due to the local homogenization of Ap-horizon soils by tillage reducing the ‘at-site’ variability. The spatial variability is distributed similarly between scales for the A- and C-horizon soils of the E–W transect. For all elements, there is significant variability at the within-40-km scale. Notwithstanding this, there is significant between-40-km variability for 28 and 20 of the elements in the A- and C-horizon data, respectively. The differences between the two transects are attributed to (1) geology, the N–S transect runs generally parallel to regional strikes, whereas the E–W transect runs across regional structures and lithologies; and (2) land use, with agricultural tillage dominating along the N–S transect. The spatial analysis of the transect data indicates that continental-scale maps demonstrating statistically significant patterns of geochemical variability may be prepared for many elements from data on soil samples collected on a 40 x 40 km grid or similar sampling designs resulting in a sample density of 1 site per 1600 km2.

Portable gamma spectrometry: measuring soil erosion in-situ at four Critical Zone Observatories in P. R. China

NASA Astrophysics Data System (ADS)

Sanderson, N. K.; Green, S. M.; Chen, Z.; Wang, J.; Wang, Y.; Wang, R.; Yu, K.; Tu, C.; Jia, X.; Li, G.; Peng, X.; Quine, T. A.

2017-12-01

Detecting patterns of soil erosion, redistribution, and/soil nutrient loss is important for long-term soil conservation and agricultural sustainability. Caesium-137 (137Cs) and other fallout radionuclide inventories have been used over the the last 50 years to track soil erosion, transport and deposition on a catchment scale, and have been shown to be useful for informing models of temporal/spatial soil redistribution. Traditional sampling methods usually involves coring, grinding, sieving, sub-sampling and laboratory analysis using HPGe detectors, all of which can be costly and time consuming. In-situ measurements can provide a mechanism for assessment of 137Cs over larger areas that integrate the spatial variability, and expand turnover of analyses. Here, we assess the applicability of an in-situ approach based on radionuclide principles, and provide a comparison of the two approaches: laboratory vs. in-situ. The UK-China Critical Zone Observatory (CZO) programme provides an ideal research platform to assess the in-situ approach to measuring soil erosion: using a portable gamma spectrometer to determine 137Cs inventories. Four extensive field slope surveys were conducted in the CZO's, which covers four ecosystem types in China: karst, red soil, peri-urban, and loess plateau. In each CZO, 3-6 plots were measured along 2 slope transects, with 3 replicated 1 hour counts of 137Cs in each plot. In addition, 137Cs soil depth and bulk density profiles were also sampled for each plot, and lab-derived inventories calculated using traditional methods for comparison. Accurately and rapidly measuring 137Cs inventories using a portable field detector allows for a greater coverage of sampling locations and the potential for small-scale spatial integration, as well as the ability to re-visit sites over time and continually adapt and improve soil erosion/redistribution models, thus more effectively targeting areas of interest with reduced cost and time constraints.

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.

Bird population and habitat surveys in urban areas

Treesearch

Richard M. DeGraaf; Aelred D. Geis; Patricia A. Healy

1991-01-01

Breeding bird populations in six habitats in Columbia. MD. were studied to develop procedures suitable for measuring bird use of residential areas and to identify habitat characteristics that define the distribution of various common bird species. A procedure to measure bird use based on 4-min transect counts on plots measuring 91 m × 91 m proved better than point...

Nutrient availability in rangeland soils: influence of prescribed burning, herbaceous vegetation removal, overseeding with Bromus tectorum, season, and elevation

Treesearch

R. R. Blank; J. Chambers; B. Roundy; A. Whittaker

2007-01-01

Soil nutrient availability influences plant invasions. Resin capsules were used to examine soil nutrient bioavailability along 2 sagebrush-grassland elevation transects in the east Tintic Range (Utah) and Shoshone Range (Nevada). In the fall of 2001, treatments were applied to 3 replicate plots at each site, which included prescribed burning, herbaceous vegetation...

Air pollution and forest health studies along a south-north transect in Poland

Treesearch

Stefan Godzik; Jerzy Szdzuj; Tomasz Staszewski; Wlodzimierz Lukasik

1998-01-01

Air pollution, bulk deposition and throughfall, soil characteristics, needle chemistry, and forest injury were studied on six permanent plots from the south (Brenna and Salmopol in the Beskidy Mountains) to the north (Gac, the Baltic Sea coastal area) in Poland. The concentrations of sulfur dioxide and nitrogen dioxide were the highest at the Katowice location and the...

Variation in soil and forest floor characteristics along gradients of ericaceous, evergreen shrub cover in the southern Appalachians

Treesearch

Jonatha L. Horton; Barton D. Clinton; John F. Walker; Colin M. Beir; Erik T. Nilsen

2009-01-01

Ericaceous shrubs can influence soil properties in many ecosystems. In this study, we examined how soil and forest floor properties vary among sites with different ericaceous evergreen shrub basal area in the southern Appalachian mountains. We randomly located plots along transects that included open understories and understories with varying amounts of Rhododendron...

Everglades Depth Estimation Network (EDEN) Applications: Tools to View, Extract, Plot, and Manipulate EDEN Data

USGS Publications Warehouse

Telis, Pamela A.; Henkel, Heather

2009-01-01

The Everglades Depth Estimation Network (EDEN) is an integrated system of real-time water-level monitoring, ground-elevation data, and water-surface elevation modeling to provide scientists and water managers with current on-line water-depth information for the entire freshwater part of the greater Everglades. To assist users in applying the EDEN data to their particular needs, a series of five EDEN tools, or applications (EDENapps), were developed. Using EDEN's tools, scientists can view the EDEN datasets of daily water-level and ground elevations, compute and view daily water depth and hydroperiod surfaces, extract data for user-specified locations, plot transects of water level, and animate water-level transects over time. Also, users can retrieve data from the EDEN datasets for analysis and display in other analysis software programs. As scientists and managers attempt to restore the natural volume, timing, and distribution of sheetflow in the wetlands, such information is invaluable. Information analyzed and presented with these tools is used to advise policy makers, planners, and decision makers of the potential effects of water management and restoration scenarios on the natural resources of the Everglades.

Temperature-dependant shifts in a wet tropical Hawaiian forest ecosystem: impact on belowground carbon stocks, dynamics, and processes

NASA Astrophysics Data System (ADS)

Crow, S. E.; Litton, C. M.; Giardina, C. P.

2009-12-01

Global patterns suggest a positive correlation between temperature and total belowground carbon (C) flux and partitioning in temperate and tropical regions, but these relationships have yet to be tested within a given ecosystem type. We established a transect of nine permanent forest plots along an elevation gradient (800-1600 m) in native-dominated Metrosideros polymorpha / Acacia koa rainforest developed in volcanic ash soils along the windward slope of Mauna Kea, Hawaii. Along the transect parent material, bedrock age, species composition, and plant available water are nearly constant and only mean annual temperature (MAT) varies substantially (13°C-18°C). We hypothesized that warmer temperatures at lower elevations would drive greater C flux and partitioning to belowground, which represents a direct input of C into belowground stocks. Roots are often sources of stabilized soil organic matter, thus we expected that increased belowground flux and partitioning of C at higher MATs would increase soil C stocks within recalcitrant C pools, even if bulk soil C stock decreases overall. In fact, our data suggest non-linear relationships between temperature and the distribution of C among soil pools based on sequential density fractionation at 1.6 and 2.4 g mL-1, and radiocarbon-based estimates of mean residence time. The proportion of C recovered within the mineral-associated heavy fraction (>2.4 g mL-1) was greatest at the highest MAT (nearly 30% of total soil C), initially declined at the mid-MAT plots (~10% of total soil C), but then increased again at the lowest MAT plots (~25%). Although the proportion of soil C within the heavy fraction was lowest at the mid-MAT plots, the mean residence time of heavy fraction C was greatest in these plots (570-663 yr for the mid-MAT plots versus 120-220 yr for the highest MAT plots and 64-308 for the lowest MAT plots), suggesting that the mineral-associated C in the mid-MAT plots was the most stabilized. In contrast, the proportion of C recovered within the rapidly cycling light fraction (<1.6 g mL-1) initially increased as MAT decreased, from <10% to a peak of nearly 50% of total soil C in the mid-MAT plots, but then decreased again in the plots with lowest MAT. High temperature both directly and indirectly stimulates weathering in these soils-which are thought to be within the phase of maximum nutrient availability, productivity, and potential SOM stabilization during ecosystem development-through increased belowground activity. However, complex feedbacks between temperature, resource allocation, weathering rate, and carbon storage may be driving non-linear relationships between temperature and soil processes.

Estimating Dungeness crab (Cancer magister) abundance: Crab pots and dive transects compared

USGS Publications Warehouse

Taggart, S. James; O'Clair, Charles E.; Shirley, Thomas C.; Mondragon, Jennifer

2004-01-01

Dungeness crabs (Cancer magister) were sampled with commercial pots and counted by scuba divers on benthic transects at eight sites near Glacier Bay, Alaska. Catch per unit of effort (CPUE) from pots was compared to the density estimates from dives to evaluate the bias and power of the two techniques. Yearly sampling was conducted in two seasons: April and September, from 1992 to 2000. Male CPUE estimates from pots were significantly lower in April than in the following September; a step-wise regression demonstrated that season accounted for more of the variation in male CPUE than did temperature. In both April and September, pot sampling was significantly biased against females. When females were categorized as ovigerous and nonovigerous, it was clear that ovigerous females accounted for the majority of the bias because pots were not biased against nonovigerous females. We compared the power of pots and dive transects in detecting trends in populations and found that pots had much higher power than dive transects. Despite their low power, the dive transects were very useful for detecting bias in our pot sampling and in identifying the optimal times of year to sample so that pot bias could be avoided.

Edge Effects in Line Intersect Sampling With

Treesearch

David L. R. Affleck; Timothy G. Gregoire; Harry T. Valentine

2005-01-01

Transects consisting of multiple, connected segments with a prescribed configuration are commonly used in ecological applications of line intersect sampling. The transect configuration has implications for the probability with which population elements are selected and for how the selection probabilities can be modified by the boundary of the tract being sampled. As...

The effect of changes to the method of estimating the pollen count from aerobiological samples.

PubMed

Sikoparija, Branko; Pejak-Šikoparija, Tatjana; Radišić, Predrag; Smith, Matt; Soldevilla, Carmen Galán

2011-02-01

Pollen data have been recorded at Novi Sad in Serbia since 2000. The adopted method of producing pollen counts has been the use of five longitudinal transects that examine 19.64% of total sample surface. However, counting five transects is time consuming and so the main objective of this study is to investigate whether reducing the number to three or even two transects would have a significant effect on daily average and bi-hourly pollen concentrations, as well as the main characteristics of the pollen season and long-term trends. This study has shown that there is a loss of accuracy in daily average and bi-hourly pollen concentrations (an increase in % ERROR) as the sub-sampling area is reduced from five to three or two longitudinal transects. However, this loss of accuracy does not impact on the main characteristics of the season or long-term trends. As a result, this study can be used to justify changing the sub-sampling method used at Novi Sad from five to three longitudinal transects. The use of two longitudinal transects has been ruled out because, although quicker, the counts produced: (a) had the greatest amount of % ERROR, (b) altered the amount of influence of the independent variable on the dependent variable (the slope in regression analysis) and (c) the total sampled surface (7.86%) was less than the minimum requirement recommended by the European Aerobiology Society working group on Quality Control (at least 10% of total slide area).

Variability of reflectance measurements with sensor altitude and canopy type

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Vanderbilt, V. C.; Pollara, V. J.

1981-01-01

Data were acquired on canopies of mature corn planted in 76 cm rows, mature soybeans planted in 96 cm rows with 71 percent soil cover, and mature soybeans planed in 76 cm rows with 100 percent soil cover. A LANDSAT band radiometer with a 15 degree field of view was used at ten altitudes ranging from 0.2 m to 10 m above the canopy. At each altitude, measurements were taken at 15 cm intervals also a 2.0 m transect perpendicular to the crop row direction. Reflectance data were plotted as a function of altitude and horizontal position to verify that the variance of measurements at low altitudes was attributable to row effects which disappear at higher altitudes where the sensor integrate across several rows. The coefficient of variation of reflectance decreased exponentially as the sensor was elevated. Systematic sampling (at odd multiples of 0.5 times the row spacing interval) required fewer measurements than simple random sampling over row crop canopies.

Effects of observers using different methods upon the total population estimates of two resident island birds

Treesearch

Sheila Conant; Mark S. Collins; C. John Ralph

1981-01-01

During a 5-week study of the Nihoa Millerbird and Nihoa Finch, we censused birds using these techniques: two line transect methods, a variable-distance circular plot method, and spot-mapping of territories (millerbirds only). Densities derived from these methods varied greatly. Due to differences in behavior, it appeared that the two species reacted differently to the...

Spatial and temporal variability of soil hydraulic properties of topsoil affected by soil erosion

NASA Astrophysics Data System (ADS)

Nikodem, Antonin; Kodesova, Radka; Jaksik, Ondrej; Jirku, Veronika; Klement, Ales; Fer, Miroslav

2014-05-01

This study is focused on the comparison of soil hydraulic properties of topsoil that is affected by erosion processes. In order to include variable morphological and soil properties along the slope three sites - Brumovice, Vidim and Sedlčany were selected. Two transects (A, B) and five sampling sites along each one were chosen. Soil samples were taken in Brumovice after the tillage and sowing of winter wheat in October 2010 and after the wheat harvest in August 2011. At locality Vidim and Sedlčany samples were collected in May and August 2012. Soil hydraulic properties were studied in the laboratory on the undisturbed 100-cm3 soil samples placed in Tempe cells using the multi-step outflow test. Soil water retention data points were obtained by calculating water balance in the soil sample at each pressure head step of the experiment. The single-porosity model in HYDRUS-1D was applied to analyze the multi-step outflow and to obtain the parameters of soil hydraulic properties using the numerical inversion. The saturated hydraulic conductivities (Ks) and unsaturated hydraulic conductivities (Kw) for the pressure head of -2 cm of topsoil were also measured after the harvest using Guelph permeameter and Minidisk tensiometer, respectively. In general soil water retention curves measured before and after vegetation period apparently differed, which indicated soil material consolidation and soil-porous system rearrangement. Soil water retention curves obtained on the soil samples and hydraulic conductivities measured in the field reflected the position at the elevation transect and the effect of erosion/accumulation processes on soil structure and consequently on the soil hydraulic properties. The highest Ks values in Brumovice were obtained at the steepest parts of the elevation transects, that have been the most eroded. The Ks values at the bottom parts decreased due to the sedimentation of eroded soil particles. The change of the Kw values along transects didn't show similar trends. However, the variability of values within both transects was low. Higher values were obtained in transect B, where the soil was more affected by erosion. The highest values of Ks as well as the value of Kw were also obtained in the steepest part of transect A in Vidim. This trend was not observed in transect B. The results corresponded with measured retention curves. Two different trends were shown in Sedlčany. While the highest values of Ks and Kw were found in the upper part of transect A, in the case of transect B the highest values were measured at the bottom of transect. Differences observed at both localities were caused by the different terrain attributes of both transects and extent of soil erosion. Acknowledgement: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic (QJ1230319).

Evaluation of radio-tracking and strip transect methods for determining foraging ranges of Black-Legged Kittiwakes

USGS Publications Warehouse

Ostrand, William D.; Drew, G.S.; Suryan, R.M.; McDonald, L.L.

1998-01-01

We compared strip transect and radio-tracking methods of determining foraging range of Black-legged Kittiwakes (Rissa tridactyla). The mean distance birds were observed from their colony determined by radio-tracking was significantly greater than the mean value calculated from strip transects. We determined that this difference was due to two sources of bias: (1) as distance from the colony increased, the area of available habitat also increased resulting in decreasing bird densities (bird spreading). Consequently, the probability of detecting birds during transect surveys also would decrease as distance from the colony increased, and (2) the maximum distance birds were observed from the colony during radio-tracking exceeded the extent of the strip transect survey. We compared the observed number of birds seen on the strip transect survey to the predictions of a model of the decreasing probability of detection due to bird spreading. Strip transect data were significantly different from modeled data; however, the field data were consistently equal to or below the model predictions, indicating a general conformity to the concept of declining detection at increasing distance. We conclude that radio-tracking data gave a more representative indication of foraging distances than did strip transect sampling. Previous studies of seabirds that have used strip transect sampling without accounting for bird spreading or the effects of study-area limitations probably underestimated foraging range.

Effects of field applications of heptachlor on bobwhite quail and other wild animals

USGS Publications Warehouse

Rosene, W.

1965-01-01

A study of the effects of field applications of heptachlor on bobwhite quail (Colinus uirginianus) and other animals was conducted on three similar areas, two in Decatur County, Georgia, and one in Escambia County, Alabama, from February, 1958, to March, 1962. Heptachlor in granules was applied by aircraft on the Georgia areas for eradication of the imported fire ant (Solenopsis saevissima). Applications were directed by personnel of the U. S. Department of Agriculture, Plant Pest Control Division. The Alabama area remained untreated. Transects where whistling cocks were counted were superimposed on areas where coveys were counted. Size of areas varied from 14,000 to 20,000 acres. Each area had six transects, totaling 11,000 acres. Whistling cock bobwhites and coveys averaged 28 and 20 per 1,000 acres, respectively, the year before treatment on a Georgia area, and cocks and coveys averaged 25 per 1,000 acres for the duration of the study on the untreated Alabama area. Where portions of an area were treated at 2 pounds of heptachlor per acre, whistling cocks and coveys were reduced significantly, with a greater reduction where a greater amount of land was treated on the area or its transects. A decline of cocks and coveys also followed 1/2-pound applications (approaching statistical significance for coveys). Three years after treatment, cock and covey numbers were below those recorded before treatment. Whistling cocks and coveys also declined on adjoining land which remained untreated (significant for cocks, approaching significance for coveys). This decline was attributed to movements of bobwhites from untreated land to repopulate treated land. There is evidence that some loss occurred in bobwhites after they moved from untreated to treated land; the decrease in each instance was ascribed to the application of heptachlor. Songbirds were listed on the two Georgia areas. The first summer, eight more species and 458 more individuals of permanent resident birds were listed on the untreated area than on the treated area. After half of the originally untreated area was treated with heptachlor at 2 pounds per acre the following winter, the number of resident birds declined 37 percent. Some species of summer resident birds could not be found on treated land after heptachlor was applied. A small plot of 4 acres was intensively searched for dead and dying animals, and observations were made on living animals. Forty-seven days after treatment, no live animals were seen or heard on the plot, and a total of 38 dead animals had been found. Soils were sampled twice after treatment, and residues had declined in the second lot of samples. Twice animals also were obtained for analysis, and residues declined in the second group. Numbers of birds increased in the same period.

Effect of Hurricane Hugo on molluscan skeletal distributions,Salt River Bay, St. Croix, U.S. Virgin Islands

NASA Astrophysics Data System (ADS)

Miller, Arnold I.; Llewellyn, Ghislaine; Parsons, Karla M.; Cummins, Hays; Boardman, Mark R.; Greenstein, Benjamin J.; Jacobs, David K.

1992-01-01

Just prior to the passage of Hurricane Hugo over St. Croix, U.S. Virgin Islands, 35 molluscan skeletal samples were collected at 30 m intervals along a sampling transect in Salt River Bay, on the north-central coast. Three months after the hurricane, the transect was resampled to permit direct assessment of storm effects on skeletal distributions. Results indicate that spatial zonation of molluscan accumulations, associated with environmental transitions along the transect, was maintained in the wake of the hurricane. However, limited transport was diagnosed by comparing the compositions of prestorm and poststorm samples from the deepest, mud-rich subenvironment on the transect. In aggregate, the species richness of samples from the southern half of this zone increased from 16 to 40, and the abundance of species that were not among the characteristic molluscs of this subenvironment increased from 11% to 26%. These storm effects could probably not have been recognized, and attributed directly to Hugo, had there been no prestorm samples with which to compare directly the poststorm samples.

Dataset of long-term monitoring of ground-dwelling ants (Hymenoptera: Formicidae) in the influence areas of a hydroelectric power plant on the Madeira River in the Amazon Basin

PubMed Central

2018-01-01

Abstract Background Biodiversity loss is accelerating rapidly in response to increasing human influence on the Earth’s natural ecosystems. One way to overcome this problem is by focusing on places of human interest and monitoring the changes and impacts on the biodiversity. This study was conducted at six sites within the influence area of the Santo Antônio Hydroelectric Power Plant in the margins of the Madeira River in Rondônia State. The sites cover a latitudinal gradient of approximately 100 km in the Brazilian Amazon Basin. The sampling design included six sampling modules with six plots (transects) each, totaling 30 sampling plots. The transects were distributed with 0 km, 0.5 km, 1 km, 2 km, 3 km and 4 km, measured perpendicularly from the river margin towards the interior of the forest. For sampling the ground-dwelling ants, the study used the ALL (ants of the leaf litter) protocol, which is standardized globally in the inventories of ant fauna. For the purpose of impact indicators, the first two campaigns (September 2011 to November 2011) were carried out in the pre-filling period, while campaigns 3 to 10 (February 2012 to November 2014) were carried out during and after the filling of the hydroelectric reservoir. A total of 253 events with a total of 9,165 occurrences were accounted during the monitoring. The ants were distributed in 10 subfamilies, 68 genera and 324 species/morphospecies. The impact on ant biodiversity during the periods before and after filling was measured by ecological indicators and by the presence and absence of some species/morphospecies. This is the first study, as far as we know, including taxonomic and ecological treatment to monitor the impact of a hydroelectric power plant on ant fauna. New information Until recently, most studies conducted on hydroelectric plants, located in the Amazon Basin, were carried out after the implementation of dams in order to assess their impacts on the environment and biodiversity (Benchimol and Peres 2015, Latrubesse et al. 2017, Sá-Oliveira et al. 2015). Recent studies on dam impacts have begun to be conducted prior to dam implementation (e.g. Bobrowiec and Tavares 2017, Fraga et al. 2014, Moser et al. 2014), thus providing a better overview of the impact and a better assessment of its magnitude. PMID:29674939

Water-quality data for the Ohio River from New Cumberland Dam to Pike Island Dam, West Virginia and Ohio, June-November 1992

USGS Publications Warehouse

Miller, Kimberly F.; Faulkenburg, C.W.; Chambers, D.B.; Waldron, M.C.

1995-01-01

This report contains water-quality data for the Ohio River, collected during the summer and fall of 1992, from river mile 51.1 (3.3 miles upstream from New Cumberland Dam) to river mile 84.0 (0.2 miles upstream from Pike Island Dam). The data were collected to assess the effects of hydropower development on water quality. Water quality was determined by a combination of repeated synoptic field measurements and laboratory analyses. Synoptic measurements were made along a longitudinal transect with 18 mid-channel sampling sites; cross-sectional transects of water quality were measured at 5 of these sites. Water-quality measurements also were made at two sites located on the back-channel (Ohio) side of Browns Island. Water temperature, dissolved oxygen concentration, pH, and specific conductance were measured at each longitudinal-transect and back-channel sampling site. Longitudinal-transect and back-channel stations were sampled at three depths (about 3.3 feet below the surface of the water, middle of the water column, and near the bottom of the river). Cross-sectional transects consisted of three or four detailed vertical pro- files of the same characteristics. Water samples were collected from three depths at the mid-channel vertical profile in each cross-sectional transect and were analyzed for concentrations of phyto- plankton photosynthetic pigments chlorophyll a and chlorophyll b. Estimates of the depth of light penetration (Secchi disk transparency) were made at pigment-sampling locations whenever light and river-surface conditions were appropriate. Synoptic sampling usually was completed in 12 hours or less and was repeated seven times between June 25 and November 6, 1992.

German-Russian project PLOT: new postglacial-glacial-preglacial pollen records from the Lakes Ladoga and Bol'shoe Shuch'e

NASA Astrophysics Data System (ADS)

Andreev, A.; Savelieva, L.; Shumilovskikh, L.; Gromig, R.; Wennrich, V.; Fedorov, G.; Wagner, B.; Melles, M.

2017-12-01

The German-Russian project PLOT (PaleolimnoLOgical Transect) investigates the Late Quaternary environmental history along the Northern Eurasia transect. Within the scope of a pilot phase of the project we have investigated Lake Ladoga, the largest lake in Europe. Although the postglacial history of the lake was studied over the last decades, the preglacial history remained unknown. It is assumed that during the Last Interglacial Lake Ladoga was part of a precursor of the Baltic Sea, which had a connection via Ladoga and Onega Lakes to the White Sea. Sediment coring at two sites in western Ladoga Lake in September 2013 has revealed sediment succession subdivided into 5 main lithological units. The sediments studied in a 22.7 m lake core were also palynologically investigated. Pollen assemblages indicate that the lowermost sediments with pollen of Betula, Alnus, Pinus, Carpinus, Quercus, Corylus, Ulmus, Tilia, remains of fresh-water Pediastrum and Botryococcus colonies as well as cysts of marine dinoflagellates and brackish water acritarchs) were accumulated during an interglacial with climate more favorable than in the Holocene. The OSL-dated samples show the late Eemian and post Eemian ages. Lake Bol'shoe Shuch'e (Polar Urals) was cored in April 2016. The thickness of the lacustrine sediments was 54 m. According to the previous studies, most of the study area has remained ice-free over the last 50-60 ka. However, the configuration and timing of the preceding glaciations has remained unclear, because of lack continuous, long-term paleoenvironmental records in the area. Preliminary studies show that the uppermost 9 m of the sediments were accumulated during the Holocene, between 11 and 9 m - in Younger Dryas, between 11 and 9 m - in Allerod, between 11 and 25 m - in MIS 2, between 25 and 54 m - in the MIS 3. We expect that the core will provide the most continuous sediment records from the whole region which can be used to reconstruct the environmental changes.

State-space modeling of population sizes and trends in Nihoa Finch and Millerbird

USGS Publications Warehouse

Gorresen, P. Marcos; Brinck, Kevin W.; Camp, Richard J.; Farmer, Chris; Plentovich, Sheldon M.; Banko, Paul C.

2016-01-01

Both of the 2 passerines endemic to Nihoa Island, Hawai‘i, USA—the Nihoa Millerbird (Acrocephalus familiaris kingi) and Nihoa Finch (Telespiza ultima)—are listed as endangered by federal and state agencies. Their abundances have been estimated by irregularly implemented fixed-width strip-transect sampling from 1967 to 2012, from which area-based extrapolation of the raw counts produced highly variable abundance estimates for both species. To evaluate an alternative survey method and improve abundance estimates, we conducted variable-distance point-transect sampling between 2010 and 2014. We compared our results to those obtained from strip-transect samples. In addition, we applied state-space models to derive improved estimates of population size and trends from the legacy time series of strip-transect counts. Both species were fairly evenly distributed across Nihoa and occurred in all or nearly all available habitat. Population trends for Nihoa Millerbird were inconclusive because of high within-year variance. Trends for Nihoa Finch were positive, particularly since the early 1990s. Distance-based analysis of point-transect counts produced mean estimates of abundance similar to those from strip-transects but was generally more precise. However, both survey methods produced biologically unrealistic variability between years. State-space modeling of the long-term time series of abundances obtained from strip-transect counts effectively reduced uncertainty in both within- and between-year estimates of population size, and allowed short-term changes in abundance trajectories to be smoothed into a long-term trend.

A forest transect of pine mountain, Kentucky: changes since E. Lucy Braun and chestnut blight

Treesearch

Tracy S. Hawkins

2006-01-01

In 1997, forest composition and structure were determined for Hi Lewis Pine Barrens State Nature Preserve, a 68-ha tract on the south slope of Pine Mountain, Harlan County, Kentucky. Data collected from 28 0.04-ha plots were used to delineate forest types. Percent canopy compositions were compared with those reported by Dr. E. Lucy Braun prior to the peak of chestnut...

Spatial heterogeneity and the distribution of bromeliad pollinators in the Atlantic Forest

NASA Astrophysics Data System (ADS)

Varassin, Isabela Galarda; Sazima, Marlies

2012-08-01

Interactions between plants and their pollinators are influenced by environmental heterogeneity, resulting in small-scale variations in interactions. This may influence pollinator co-existence and plant reproductive success. This study, conducted at the Estação Biológica de Santa Lúcia (EBSL), a remnant of the Atlantic Forest in southeastern Brazil, investigated the effect of small-scale spatial variations on the interactions between bromeliads and their pollinators. Overall, hummingbirds pollinated 19 of 23 bromeliad species, of which 11 were also pollinated by bees and/or butterflies. However, spatial heterogeneity unrelated to the spatial location of plots or bromeliad species abundance influenced the presence of pollinators. Hummingbirds were the most ubiquitous pollinators at the high-elevation transect, with insect participation clearly declining as transect elevation increased. In the redundancy analysis, the presence of the hummingbird species Phaethornis eurynome, Phaethornis squalidus, Ramphodon naevius, and Thalurania glaucopis, and the butterfly species Heliconius erato and Heliconius nattereri in each plot was correlated with environmental factors such as bromeliad and tree abundance, and was also correlated with horizontal diversity. Since plant-pollinator interactions varied within the environmental mosaics at the study site, this small-scale environmental heterogeneity may relax competition among pollinators, and may explain the high diversity of bromeliads and pollinators generally found in the Atlantic Forest.

Evaluation of terrestrial and streamside salamander monitoring techniques at Shenandoah National Park

USGS Publications Warehouse

Jung, R.E.; Droege, S.; Sauer, J.R.; Landy, R.B.

2000-01-01

In response to concerns about amphibian declines, a study evaluating and validating amphibian monitoring techniques was initiated in Shenandoah and Big Bend National Parks in the spring of 1998. We evaluate precision, bias, and efficiency of several sampling methods for terrestrial and streamside salamanders in Shenandoah National Park and assess salamander abundance in relation to environmental variables, notably soil and water pH. Terrestrial salamanders, primarily redback salamanders (Plethodon cinereus), were sampled by searching under cover objects during the day in square plots (10 to 35 m2). We compared population indices (mean daily and total counts) with adjusted population estimates from capture-recapture. Analyses suggested that the proportion of salamanders detected (p) during sampling varied among plots, necessitating the use of adjusted population estimates. However, adjusted population estimates were less precise than population indices, and may not be efficient in relating salamander populations to environmental variables. In future sampling, strategic use of capture-recapture to verify consistency of p's among sites may be a reasonable compromise between the possibility of bias in estimation of population size and deficiencies due to inefficiency associated with the estimation of p. The streamside two-lined salamander (Eurycea bislineata) was surveyed using four methods: leaf litter refugia bags, 1 m2 quadrats, 50 x 1 m visual encounter transects, and electric shocking. Comparison of survey methods at nine streams revealed congruent patterns of abundance among sites, suggesting that relative bias among the methods is similar, and that choice of survey method should be based on precision and logistical efficiency. Redback and two-lined salamander abundance were not significantly related to soil or water pH, respectively.

Linking Land-Use to Submarine Groundwater Discharge Nutrient Fluxes on Maui, Hawaii

NASA Astrophysics Data System (ADS)

Bishop, J. M.; Glenn, C. R.; Amato, D. W.; Dulaiova, H.

2014-12-01

Fertilized agricultural lands, wastewater injection, and areas with high septic system density each have substantial potential for contributing excess nutrients to the coastal waters of islands via submarine groundwater discharge (SGD). We evaluated the coastal impacts of such land-use around the island of Maui using stable isotopes (δ15N of NO3-; δ18O and δ2H of H2O) and nutrient concentrations from wells, springs, beach seeps, SGD, and coastal waters, and coupled these to coastal water SGD and nutrient fluxes using 222Rn mass balance. Flowpaths and recharge elevations for groundwater samples were determined using the δ18OH2O of samples, recharge data, modeled groundwater head, and published local meteoric water lines. Coastal groundwater samples whose flowpaths transect sugarcane plots showed highest dissolved inorganic nitrogen (DIN - NO3- + NO2-) concentrations, ranging from 225 - 450 µM, and the δ15N of those samples was on average 3.3 ± 0.6 ‰ (n = 15), as expected for urea fertilizers applied to commercial sugarcane. Samples whose flowpaths transect large amounts of septic sources showed moderate DIN concentrations (max. 100 µM), but had higher δ15N values (9.7 ± 4.8 ‰, n = 5), reflecting their sewage influence. Due to nitrate reduction during subterranean transit, groundwater and coastal waters proximal to deep, near-coast wastewater injection (Kahului) display the highest average δ15N values encountered (δ15NNO3- 18.8 ± 11.1 ‰, n = 19) and moderate DIN concentrations (max 90 µM). Average SGD nutrient fluxes among the different field sites ranged from 700 - 1,500,000 µmol/d/m of shoreline for DIN and 600 - 22,000 µmol/d/m for orthophosphate. These results indicate that areas with the highest N and P fluxes are areas where coastal groundwater flowpaths transect large tracts of sugarcane production. Although highest SGD rates occur near the Kahului wastewater injection wells (~ 2800 m3/day) the relatively low nutrient concentrations in the groundwater end member lead to comparatively modest nutrient fluxes of 270,000 and 13,000 μmol/d/m for DIN and orthophosphate, respectively. This study demonstrates the utility of coupling stable isotope and SGD-radioisotope tracers to (1) determine the source of nutrients in SGD as well as (2) the trajectories and specific fluxes of those nutrients to the coast.

Relationships among environmental variables and distribution of tree species at high elevation in the Olympic Mountains

USGS Publications Warehouse

Woodward, Andrea

1998-01-01

Relationships among environmental variables and occurrence of tree species were investigated at Hurricane Ridge in Olympic National Park, Washington, USA. A transect consisting of three plots was established down one north-and one south-facing slope in stands representing the typical elevational sequence of tree species. Tree species included subalpine fir (Abies lasiocarpa), Douglas-fir (Pseudotsuga menziesii), mountain hemlock (Tsuga mertensiana), and Pacific silver fir (Abies amabilis). Air and soil temperature, precipitation, and soil moisture were measured during three growing seasons. Snowmelt patterns, soil carbon and moisture release curves were also determined. The plots represented a wide range in soil water potential, a major determinant of tree species distribution (range of minimum values = -1.1 to -8.0 MPa for Pacific silver fir and Douglas-fir plots, respectively). Precipitation intercepted at plots depended on topographic location, storm direction and storm type. Differences in soil moisture among plots was related to soil properties, while annual differences at each plot were most often related to early season precipitation. Changes in climate due to a doubling of atmospheric CO2 will likely shift tree species distributions within, but not among aspects. Change will be buffered by innate tolerance of adult trees and the inertia of soil properties.

Transect versus grid trapping arrangements for sampling small-mammal communities

Treesearch

Dean E. Pearson; Leonard F. Ruggiero

2003-01-01

We compared transect and grid trapping arrangements for assessing small-mammal community composition and relative abundance for 2 years in 2 forest cover types in west-central Montana, USA. Transect arrangements yielded more total captures, more individual captures, and more species than grid arrangements in both cover types in both years. Differences between...

Impact of winter roads on boreal peatland carbon exchange.

PubMed

Strack, Maria; Softa, Divya; Bird, Melanie; Xu, Bin

2018-01-01

Across Canada's boreal forest, linear disturbances, including cutlines such as seismic lines and roads, crisscross the landscape to facilitate resource exploration and extraction; many of these linear disturbances cross peatland ecosystems. Changes in tree canopy cover and the compression of the peat by heavy equipment alter local thermal, hydrological, and ecological conditions, likely changing carbon exchange on the disturbance, and possibly in the adjacent peatland. We measured bulk density, water table, soil temperature, plant cover, and CO 2 and CH 4 flux along triplicate transects crossing a winter road through a wooded fen near Peace River, Alberta, Canada. Sample plots were located 1, 5, and 10 m from the road on both sides with an additional three plots on the road. Productivity of the overstory trees, when present, was also determined. The winter road had higher bulk density, shallower water table, higher graminoid cover, and thawed earlier than the adjacent peatland. Tree productivity and CO 2 flux varied between the plots, and there was no clear pattern in relation to distance from the road. The plots on the winter road acted as a greater CO 2 sink and greater CH 4 source compared to the adjacent peatland with plots on the winter road emitting on average (standard error) 479 (138) compared to 41 (10) mg CH 4  m -2  day -1 in the adjacent peatland. Considering both gases, global warming potential increased from 70 to 250 g CO 2 e m -2  year -1 in the undisturbed area to 2100 g CO 2 e m -2  year -1 on the winter road. Although carbon fluxes on any given cutline through peatland will vary depending on level of compaction, line width and vegetation community shifts, the large number of linear disturbances in Canada's boreal forest and slow recovery on peatland ecosites suggest they could represent an important anthropogenic greenhouse gas source. © 2017 John Wiley & Sons Ltd.

A survey of the occurrence of Bacillus anthracis in North American soils over two long-range transects and within post-Katrina New Orleans

USGS Publications Warehouse

Griffin, Dale W.; Petrosky, Terry; Morman, Suzette A.; Luna, Vicki A.

2009-01-01

Soil samples were collected along a north-south transect extending from Manitoba, Canada, to the US-Mexico border near El Paso, Texas in 2004 (104 samples), a group of sites within New Orleans, Louisiana following Hurricane Katrina in 2005 (19 samples), and a Gulf Coast transect extending from Sulphur, Louisiana, to DeFuniak Springs, Florida, in 2007 (38 samples). Samples were collected from the top 40 cm of soil and were screened for the presence of total Bacillus species and Bacillus anthracis (anthrax), specifically using multiplex-polymerase chain reaction (PCR). Using an assay with a sensitivity of ~170 equivalent colony-forming units (CFU) g-1 field moist soil, the prevalence rate of Bacillus sp./B. anthracis in the north-south transect and the 2005 New Orleans post-Katrina sample set were 20/5% and 26/26%, respectively. Prevalence in the 2007 Gulf Coast sample set using an assay with a sensitivity of ~4 CFU g-1 of soil was 63/0%. Individual transect-set data indicate a positive relation between occurrences of species and soil moisture or soil constituents (i.e., Zn and Cu content). The 2005 New Orleans post-Katrina data indicated that B. anthracis is readily detectable in Gulf Coast soils following flood events. The data also indicated that occurrence, as it relates to soil chemistry, may be confounded by flood-induced dissemination of germinated cells and the mixing of soil constituents for short temporal periods following an event.

A survey of the occurrence of Bacillus anthracis in North American soils over two long-range transects and within post-Katrina New Orleans

USGS Publications Warehouse

Griffin, Dale W.; Petrosky, T.; Morman, S.A.; Luna, V.A.

2009-01-01

Soil samples were collected along a north-south transect extending from Manitoba, Canada, to the US-Mexico border near El Paso, Texas in 2004 (104 samples), a group of sites within New Orleans, Louisiana following Hurricane Katrina in 2005 (19 samples), and a Gulf Coast transect extending from Sulphur, Louisiana, to DeFuniak Springs, Florida, in 2007 (38 samples). Samples were collected from the top 40 cm of soil and were screened for the presence of total Bacillus species and Bacillus anthracis (anthrax), specifically using multiplex-polymerase chain reaction (PCR). Using an assay with a sensitivity of ???170 equivalent colony-forming units (CFU) g-1 field moist soil, the prevalence rate of Bacillus sp./B. anthracis in the north-south transect and the 2005 New Orleans post-Katrina sample set were 20/5% and 26/26%, respectively. Prevalence in the 2007 Gulf Coast sample set using an assay with a sensitivity of ???4 CFU g-1 of soil was 63/0%. Individual transect-set data indicate a positive relation between occurrences of species and soil moisture or soil constituents (i.e., Zn and Cu content). The 2005 New Orleans post-Katrina data indicated that B. anthracis is readily detectable in Gulf Coast soils following flood events. The data also indicated that occurrence, as it relates to soil chemistry, may be confounded by flood-induced dissemination of germinated cells and the mixing of soil constituents for short temporal periods following an event.

SPRUCE Deep Peat Microbial Diversity, CO2 and CH4 Production in Response to Nutrient, Temperature, and pH Treatments during Incubation Studies.

DOE Data Explorer

A., Kluber Laurel [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Allen, Samantha A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hendershot, Nicholas [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, Paul J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Schadt, Christopher W. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2014-09-01

This data set contains the results of a microcosm incubation study on deep peat collected from the SPRUCE experimental site in the S1 Bog in September 2014. Microcosms were monitored for CO2 and CH4 production, and microbial community dynamics were assessed using qPCR and amplicon sequencing.The experiment was designed with a full factorial design with elevated temperature, nitrogen (N), (P), and pH treatments was used with samples from each transect serving replicates. In all, 96 microcosms were constructed to account for the 16 treatment combinations (N x P x pH x temperature), 2 time points, and 3 replicates. Temperature treatments were 6 °C, to mimic the SPRUCE ambient plot temperatures, and 15 °C to mimic the SPRUCE +9 °C treatment.

Geosphere-biosphere circulation of chemical elements in soil and plant systems from a 100 km transect from southern central Norway.

PubMed

Reimann, Clemens; Fabian, Karl; Flem, Belinda; Andersson, Malin; Filzmoser, Peter; Englmaier, Peter

2018-05-17

Geochemical element separation is studied in 14 different sample media collected at 41 sites along an approximately 100-km long transect north of Oslo. At each site, soil C and O horizons and 12 plant materials (birch/spruce/cowberry/blueberry leaves/needles and twigs, horsetail, braken fern, pine bark and terrestrial moss) were sampled. The observed concentrations of 29 elements (K, Ca, P, Mg, Mn, S, Fe, Zn, Na, B, Cu, Mo, Co, Al, Ba, Rb, Sr, Ti, Ni, Pb, Cs, Cd, Ce, Sn, La, Tl, Y, Hg, Ag) were used to investigate soil-plant relations, and to evaluate the element differentiation between different plants, or between foliage and twigs of the same plant. In relation to the soil C horizon, the O horizon is strongly enriched (O/C ratio > 5) in Ag, Hg, Cd, Sn, S and Pb. Other elements (B, K, Ca, P, S, Mn) show higher concentrations in the plants than in the substrate represented by the C horizon, and often even higher concentrations than in the soil O horizon. Elements like B, K, Ca, S, Mg, P, Ba, and Cu are well tuned to certain concentration levels in most of the plants. This is demonstrated by their lower interquartile variability in the plants than in the soil. Cross-plots of element concentration, variance, and ratios, supported by linear discrimination analysis, establish that different plants are marked by their individual element composition, which is separable from, and largely independent of the natural substrate variability across the Gjøvik transect. Element allocation to foliage or twigs of the same plants can also be separated and thus dominantly depend on metabolism, physiology, and structure linked to biological functions, and only to a lesser degree on the substrate and environmental background. The results underline the importance of understanding the biological mechanisms of plant-soil interaction in order to correctly quantify anthropogenic impact on soil and plant geochemistry. Copyright © 2018 Elsevier B.V. All rights reserved.

Methods for the quantification of coarse woody debris and an examination of its spatial patterning: A study from the Tenderfoot Creek Experimental Forest, MT

Treesearch

Paul B. Alaback; Duncan C. Lutes

1997-01-01

Methods for the quantification of coarse woody debris volume and the description of spatial patterning were studied in the Tenderfoot Creek Experimental Forest, Montana. The line transect method was found to be an accurate, unbiased estimator of down debris volume (> 10cm diameter) on 1/4 hectare fixed-area plots, when perpendicular lines were used. The Fischer...

Correction for slope in point and transect relascope sampling of downed coarse woody debris

Treesearch

Goran Stahl; Anna Ringvall; Jeffrey H. Gove; Mark J. Ducey

2002-01-01

In this article, the effect of sloping terrain on estimates in point and transect relascope sampling (PRS and TRS, respectively) is studied. With these inventory methods, a wide angle relascope is used either from sample points (PRS) or along survey lines (TRS). Characteristics associated with line-shaped objects on the ground are assessed, e.g., the length or volume...

Design of a factorial experiment with randomization restrictions to assess medical device performance on vascular tissue.

PubMed

Diestelkamp, Wiebke S; Krane, Carissa M; Pinnell, Margaret F

2011-05-20

Energy-based surgical scalpels are designed to efficiently transect and seal blood vessels using thermal energy to promote protein denaturation and coagulation. Assessment and design improvement of ultrasonic scalpel performance relies on both in vivo and ex vivo testing. The objective of this work was to design and implement a robust, experimental test matrix with randomization restrictions and predictive statistical power, which allowed for identification of those experimental variables that may affect the quality of the seal obtained ex vivo. The design of the experiment included three factors: temperature (two levels); the type of solution used to perfuse the artery during transection (three types); and artery type (two types) resulting in a total of twelve possible treatment combinations. Burst pressures of porcine carotid and renal arteries sealed ex vivo were assigned as the response variable. The experimental test matrix was designed and carried out as a split-plot experiment in order to assess the contributions of several variables and their interactions while accounting for randomization restrictions present in the experimental setup. The statistical software package SAS was utilized and PROC MIXED was used to account for the randomization restrictions in the split-plot design. The combination of temperature, solution, and vessel type had a statistically significant impact on seal quality. The design and implementation of a split-plot experimental test-matrix provided a mechanism for addressing the existing technical randomization restrictions of ex vivo ultrasonic scalpel performance testing, while preserving the ability to examine the potential effects of independent factors or variables. This method for generating the experimental design and the statistical analyses of the resulting data are adaptable to a wide variety of experimental problems involving large-scale tissue-based studies of medical or experimental device efficacy and performance.

Variation of maximum tree height and annual shoot growth of Smith fir at various elevations in the Sygera Mountains, southeastern Tibetan Plateau.

PubMed

Wang, Yafeng; Čufar, Katarina; Eckstein, Dieter; Liang, Eryuan

2012-01-01

Little is known about tree height and height growth (as annual shoot elongation of the apical part of vertical stems) of coniferous trees growing at various altitudes on the Tibetan Plateau, which provides a high-elevation natural platform for assessing tree growth performance in relation to future climate change. We here investigated the variation of maximum tree height and annual height increment of Smith fir (Abies georgei var. smithii) in seven forest plots (30 m×40 m) along two altitudinal transects between 3,800 m and 4,200/4,390 m above sea level (a.s.l.) in the Sygera Mountains, southeastern Tibetan Plateau. Four plots were located on north-facing slopes and three plots on southeast-facing slopes. At each site, annual shoot growth was obtained by measuring the distance between successive terminal bud scars along the main stem of 25 trees that were between 2 and 4 m high. Maximum/mean tree height and mean annual height increment of Smith fir decreased with increasing altitude up to the tree line, indicative of a stress gradient (the dominant temperature gradient) along the altitudinal transect. Above-average mean minimum summer (particularly July) temperatures affected height increment positively, whereas precipitation had no significant effect on shoot growth. The time series of annual height increments of Smith fir can be used for the reconstruction of past climate on the southeastern Tibetan Plateau. In addition, it can be expected that the rising summer temperatures observed in the recent past and anticipated for the future will enhance Smith fir's growth throughout its altitudinal distribution range.

Observed effects of an exceptional drought on tree mortality in a tropical dry forest

NASA Astrophysics Data System (ADS)

Medvigy, D.; Vargas, G.; Xu, X.; Smith, C. M.; Becknell, J.; Brodribb, T.; Powers, J. S.

2016-12-01

Climate models predict that the coming century will bring reduced rainfall to Neotropical dry forests. It is unknown how tropical dry forest trees will respond to such rainfall reductions. Will there be increased mortality? If so, what will be the dominant mechanism of mortality? Will certain functional groups or size classes be more susceptible to unusually dry conditions and do functional traits underlie these patterns? With these questions in mind, we analyzed the response of trees from 18 Costa Rican tropical dry forest inventory plots and from additional transects to the exceptional 2015 drought that coincided with a strong ENSO event. We compared stand-level mortality rates observed during pre-drought years (2008-2014) and during the drought year of 2015 in the inventory plots. For both inventory plots and transects, we analyzed whether particular functional groups or size classes experienced exceptional mortality after the drought. We found that mortality rates were two to three times higher during the drought than before the drought. In contrast to observations at moist tropical forests, tree size had little influence on mortality. In terms of functional groups, mortality rates of evergreen oaks growing on nutrient-poor soils particularly increased during drought. Legumes seemed less affected by the drought than non-legumes. However, elevated mortality rates were not clearly correlated with commonly-measured traits like wood density or specific leaf area. Instead, hydraulic traits like P50 or turgor loss point may be better predictors of drought-driven mortality. In addition, trees that died during the drought tended to have smaller relative growth rate prior to the drought than trees that survived the drought.

Water-quality data for the Ohio River from Willow Island Dam to Belleville Dam, West Virginia and Ohio, June-October 1991

USGS Publications Warehouse

Chambers, D.B.; Miller, K.F.; Waldron, M.C.; Falkenburg, C.W.

1994-01-01

This report contains water-quality data for the Ohio River from river mile 160.6 (1.1 mi upstream from Willow Island Dam) to river mile 203.6 (0.3 mi upstream from Belleville Dam) during the summer of 1991. Water quality was determined by a combi- nation of synoptic field measurements and laboratory analyses. Synoptic sampling consisted of 8 cross-sectional transects and a longitudinal transect with 28 mid-channel stations. Each cross- sectional transect included five vertical profiles of water temperature, dissolved oxygen concen- tration, pH, and specific conductance. Longi- tudinal transect stations were sampled at three depths (near the surface, middle of the water column, and at or near the bottom) for the same characteristics. Sampling was completed in 3 days or less, and was repeated approximately every 2 weeks from June through October 1991. Beginning in August 1991, water samples were collected at selected locations and analyzed for chlorophyll-a and pheophytin concentrations, as measures of phytoplankton biomass and phytoplankton-degradation products, respectively. The depth of light penetration was estimated at all pigment-sampling locations.

Groundwater and surface-water interaction, water quality, and processes affecting loads of dissolved solids, selenium, and uranium in Fountain Creek near Pueblo, Colorado, 2012–2014

USGS Publications Warehouse

Arnold, L. Rick; Ortiz, Roderick F.; Brown, Christopher R.; Watts, Kenneth R.

2016-11-28

In 2012, the U.S. Geological Survey, in cooperation with the Arkansas River Basin Regional Resource Planning Group, initiated a study of groundwater and surface-water interaction, water quality, and loading of dissolved solids, selenium, and uranium to Fountain Creek near Pueblo, Colorado, to improve understanding of sources and processes affecting loading of these constituents to streams in the Arkansas River Basin. Fourteen monitoring wells were installed in a series of three transects across Fountain Creek near Pueblo, and temporary streamgages were established at each transect to facilitate data collection for the study. Groundwater and surface-water interaction was characterized by using hydrogeologic mapping, groundwater and stream-surface levels, groundwater and stream temperatures, vertical hydraulic-head gradients and ratios of oxygen and hydrogen isotopes in the hyporheic zone, and streamflow mass-balance measurements. Water quality was characterized by collecting periodic samples from groundwater, surface water, and the hyporheic zone for analysis of dissolved solids, selenium, uranium, and other selected constituents and by evaluating the oxidation-reduction condition for each groundwater sample under different hydrologic conditions throughout the study period. Groundwater loads to Fountain Creek and in-stream loads were computed for the study area, and processes affecting loads of dissolved solids, selenium, and uranium were evaluated on the basis of geology, geochemical conditions, land and water use, and evapoconcentration.During the study period, the groundwater-flow system generally contributed flow to Fountain Creek and its hyporheic zone (as a single system) except for the reach between the north and middle transects. However, the direction of flow between the stream, the hyporheic zone, and the near-stream aquifer was variable in response to streamflow and stage. During periods of low streamflow, Fountain Creek generally gained flow from groundwater. However, during periods of high streamflow, the hydraulic gradient between groundwater and the stream temporarily reversed, causing the stream to lose flow to groundwater.Concentrations of dissolved solids, selenium, and uranium in groundwater generally had greater spatial variability than surface water or hyporheic-zone samples, and constituent concentrations in groundwater generally were greater than in surface water. Constituent concentrations in the hyporheic zone typically were similar to or intermediate between concentrations in groundwater and surface water. Concentrations of dissolved solids, selenium, uranium, and other constituents in groundwater samples collected from wells located on the east side of the north monitoring well transect were substantially greater than for other groundwater, surface-water, and hyporheic-zone samples. With one exception, groundwater samples collected from wells on the east side of the north transect exhibited oxic to mixed (oxic-anoxic) conditions, whereas most other groundwater samples exhibited anoxic to suboxic conditions. Concentrations of dissolved solids, selenium, and uranium in surface water generally increased in a downstream direction along Fountain Creek from the north transect to the south transect and exhibited an inverse relation to streamflow with highest concentration occurring during periods of low streamflow and lowest concentrations occurring during periods of high streamflow.Groundwater loads of dissolved solids, selenium, and uranium to Fountain Creek were small because of the small amount of groundwater flowing to the stream under typical low-streamflow conditions. In-stream loads of dissolved solids, selenium, and uranium in Fountain Creek varied by date, primarily in relation to streamflow at each transect and were much larger than computed constituent loads from groundwater. In-stream loads generally decreased with decreases in streamflow and increased as streamflow increased. In-stream loads of dissolved solids and selenium increased between the north and middle transects but generally decreased between the middle and south transects. By contrast, uranium loads generally decreased between the north and middle transects but increased between the middle and south transects. In-stream load differences between transects appear primarily to be related to differences in streamflow. However, because groundwater typically flows to Fountain Creek under low-flow conditions, and groundwater has greater concentrations of dissolved solids, selenium, and uranium than surface water in Fountain Creek, increases in loads between transects likely are affected by inflow of groundwater to the stream, which can account for a substantial proportion of the in-stream load difference between transects. When loads decreased between transects, the primary cause likely was decreased streamflow as a result of losses to groundwater and flow through the hyporheic zone. However, localized groundwater inflow likely attenuated the magnitude by which the in-stream loads decreased.The combination of localized soluble geologic sources and oxic conditions likely is the primary reason for the occurrence of high concentrations of dissolved solids, selenium, and uranium in groundwater on the east side of the north monitoring well transect. To evaluate conditions potentially responsible for differences in water quality and redox conditions, physical characteristics such as depth to water, saturated thickness, screen depth below the water table, screen height above bedrock, and aquifer hydraulic conductivity were compared by using Wilcoxon rank-sum tests. Results indicated no significant difference between depth to water, screen height above bedrock, and hydraulic conductivity for groundwater samples collected from wells on the east side of the north transect and groundwater samples from all other wells. However, saturated thickness and screen depth below the water table both were significantly smaller for groundwater samples collected from wells on the east side of the north transect than for groundwater samples from other wells, indicating that these characteristics might be related to the elevated constituent concentrations found at that location. Similarly, saturated thickness and screen depth below the water table were significantly smaller for groundwater samples under oxic or mixed (oxic-anoxic) conditions than for those under anoxic to suboxic conditions.The greater constituent concentrations at wells on the east side of the north transect also could, in part, be related to groundwater discharge from an unnamed alluvial drainage located directly upgradient from that location. Although the quantity and quality of water discharging from the drainage is not known, the drainage appears to collect water from a residential area located upgradient to the east of the wells, and groundwater could become concentrated in nitrate and other dissolved constituents before flowing through the drainage. High levels of nitrate, whether from anthropogenic or natural geologic sources, could promote more soluble forms of selenium and other constituents by affecting the redox condition of groundwater. Whether oxic conditions at wells on the east side of the north transect are the result of physical characteristics or of groundwater inflow from the alluvial drainage, the oxic conditions appear to cause increased dissolution of minerals from the shallow shale bedrock at that location. Because ratios of hydrogen and oxygen isotopes indicate evaporation likely has not had a substantial effect on groundwater, constituent concentrations at that location likely are not the result of evapoconcentration. 

Mass discharge in a tracer plume: Evaluation of the Theissen Polygon Method

PubMed Central

Mackay, Douglas M.; Einarson, Murray D.; Kaiser, Phil M.; Nozawa-Inoue, Mamie; Goyal, Sham; Chakraborty, Irina; Rasa, Ehsan; Scow, Kate M.

2013-01-01

A tracer plume was created within a thin aquifer by injection for 299 days of two adjacent “sub-plumes” to represent one type of plume heterogeneity encountered in practice. The plume was monitored by snapshot sampling of transects of fully screened wells. The mass injection rate and total mass injected were known. Using all wells in each transect (0.77 m well spacing, 1.4 points/m2 sampling density), the Theissen Polygon Method (TPM) yielded apparently accurate mass discharge (Md) estimates at 3 transects for 12 snapshots. When applied to hypothetical sparser transects using subsets of the wells with average spacing and sampling density from 1.55 to 5.39 m and 0.70 to 0.20 points/m2, respectively, the TPM accuracy depended on well spacing and location of the wells in the hypothesized transect with respect to the sub-plumes. Potential error was relatively low when the well spacing was less than the widths of the sub-plumes (> 0.35 points/m2). Potential error increased for well spacing similar to or greater than the sub-plume widths, or when less than 1% of the plume area was sampled. For low density sampling of laterally heterogeneous plumes, small changes in groundwater flow direction can lead to wide fluctuations in Md estimates by the TPM. However, sampling conducted when flow is known or likely to be in a preferred direction can potentially allow more useful comparisons of Md over multiyear time frames, such as required for performance evaluation of natural attenuation or engineered remediation systems. PMID:22324777

Characterising Vegetation Structural and Functional Differences Across Australian Ecosystems From a Network of Terrestrial Laser Scanning Survey Sites and Airborne and Satellite Image Archives

NASA Astrophysics Data System (ADS)

Phinn, S. R.; Armston, J.; Scarth, P.; Johansen, K.; Schaefer, M.; Suarez, L.; Soto-Berelov, M.; Muir, J.; Woodgate, W.; Jones, S.; Held, A. A.

2015-12-01

Vegetation structural information is critical for environmental monitoring, management and compliance assessment. In this context we refer to vegetation structural properties as vertical, horizontal and volumetric dimensions, including: canopy height; amount and distribution of vegetation by height; foliage projective cover (FPC); leaf area index (LAI); and above ground biomass. Our aim was to determine if there were significant differences between vegetation structural properties across 11 ecosystem types in Australia as measured by terrestrial laser scanner (TLS) structure metrics. The ecosystems sampled included: mesophyll vineforest, wet-dry tropical savannah, mallee woodland, subtropical eucalypt forest, mulga woodland/grassland, wet eucalypt forest, dry eucalypt forest, tall and wet eucalypt forest, and desert grassland/shrublands. Canopy height, plant area-height profiles and LAI were calculated from consistently processed TLS data using Australia's Terrestrial Ecosystem Research Network's (TERN) Supersites by the TERN AusCover remote sensing field teams from 2012-2015. The Supersites were sampled using standardised field protocols within a core set of 1 ha plots as part of a 5 km x 5 km uniform area using a RIEGL-VZ400 waveform recording TLS. Four to seven scans were completed per plot, with one centre point and then at 25 m away from the centre point along transect lines at 0o, 60o and 240o. Individual foliage profiles were sensitive to spatial variation in the distribution of plant materials. Significant differences were visible between each of the vegetation communities assessed when aggregated to plot and ecosystem type scales. Several of the communities exhibited simple profiles with either grass and shrubs (e.g. desert grassland) or grass and trees (e.g. mallee woodland). Others had multiple vegetation forms at different heights, contributing to the profile (e.g. wet eucalypt forest). The TLS data provide significantly more detail about the relative vertical and horizontal distribution of plant materials. TLS data are providing a step change in satellite image based vegetation mapping, and refining our knowledge of vegetation structure and its phenological variability. Open access plot scale TLS measurements are available through the TERN Auscover data portal.

Improving Aquatic Warbler Population Assessments by Accounting for Imperfect Detection

PubMed Central

Oppel, Steffen; Marczakiewicz, Piotr; Lachmann, Lars; Grzywaczewski, Grzegorz

2014-01-01

Monitoring programs designed to assess changes in population size over time need to account for imperfect detection and provide estimates of precision around annual abundance estimates. Especially for species dependent on conservation management, robust monitoring is essential to evaluate the effectiveness of management. Many bird species of temperate grasslands depend on specific conservation management to maintain suitable breeding habitat. One such species is the Aquatic Warbler (Acrocephalus paludicola), which breeds in open fen mires in Central Europe. Aquatic Warbler populations have so far been assessed using a complete survey that aims to enumerate all singing males over a large area. Because this approach provides no estimate of precision and does not account for observation error, detecting moderate population changes is challenging. From 2011 to 2013 we trialled a new line transect sampling monitoring design in the Biebrza valley, Poland, to estimate abundance of singing male Aquatic Warblers. We surveyed Aquatic Warblers repeatedly along 50 randomly placed 1-km transects, and used binomial mixture models to estimate abundances per transect. The repeated line transect sampling required 150 observer days, and thus less effort than the traditional ‘full count’ approach (175 observer days). Aquatic Warbler abundance was highest at intermediate water levels, and detection probability varied between years and was influenced by vegetation height. A power analysis indicated that our line transect sampling design had a power of 68% to detect a 20% population change over 10 years, whereas raw count data had a 9% power to detect the same trend. Thus, by accounting for imperfect detection we increased the power to detect population changes. We recommend to adopt the repeated line transect sampling approach for monitoring Aquatic Warblers in Poland and in other important breeding areas to monitor changes in population size and the effects of habitat management. PMID:24713994

Digital radiography and historical contextualisation of the 19th century modified human skeletal remains from the Worcester Royal Infirmary, England.

PubMed

Western, A G; Bekvalac, J

2015-09-01

Recent excavations at the Worcester Royal Infirmary revealed a large assemblage of modified skeletal remains dating to the late 19th century. The assemblage included a sample of 134 long bones, 76 of which were transected and 58 of which displayed evidence of gross pathology without transection. Transection may have been undertaken for the purposes of amputation, anatomical or morbid dissection, for surgical training or specimen preparation. In order to elucidate the motives for such modification, Direct Digital Radiography (DDR) was undertaken on the proximal and distal elements present to confirm the true prevalence of disease. The radiographic evidence revealed that some transected elements exhibited previously unobserved pathological changes. The ratios of proximal to distal elements varied between samples of pathological and non-pathological transected elements, suggesting different motives for modification. There was also a significant difference between the composition of the skeletal sample and that expected from historical records of amputation. Aggressive or acute/subacute as well as chronic stages of disease were observed, some lesions possibly relating to ascending infection following gangrenous limb ischaemia or haematogenous spread. Other rare conditions were detected using DDR, proving it to be a critical tool in the assessment of skeletal disease in the past. Copyright © 2015 Elsevier Inc. All rights reserved.

Estimating nest detection probabilities for white-winged dove nest transects in Tamaulipas, Mexico

USGS Publications Warehouse

Nichols, J.D.; Tomlinson, R.E.; Waggerman, G.

1986-01-01

Nest transects in nesting colonies provide one source of information on White-winged Dove (Zenaida asiatica asiatica) population status and reproduction. Nests are counted along transects using standardized field methods each year in Texas and northeastern Mexico by personnel associated with Mexico's Office of Flora and Fauna, the Texas Parks and Wildlife Department, and the U.S. Fish and Wildlife Service. Nest counts on transects are combined with information on the size of nesting colonies to estimate total numbers of nests in sampled colonies. Historically, these estimates have been based on the actual nest counts on transects and thus have required the assumption that all nests lying within transect boundaries are detected (seen) with a probability of one. Our objectives were to test the hypothesis that nest detection probability is one and, if rejected, to estimate this probability.

Major- and trace-element concentrations in soils from two continental-scale transects of the United States and Canada

USGS Publications Warehouse

Smith, David B.; Cannon, William F.; Woodruff, Laurel G.; Garrett, Robert G.; Klassen, Rodney; Kilburn, James E.; Horton, John D.; King, Harley D.; Goldhaber, Martin B.; Morrison, Jean M.

2005-01-01

This report contains major- and trace-element concentration data for soil samples collected from 265 sites along two continental-scale transects in North America. One of the transects extends from northern Manitoba to the United States-Mexico border near El Paso, Tex. and consists of 105 sites. The other transect approximately follows the 38th parallel from the Pacific coast of the United States near San Francisco, Calif., to the Atlantic coast along the Maryland shore and consists of 160 sites. Sampling sites were defined by first dividing each transect into approximately 40-km segments. For each segment, a 1-km-wide latitudinal strip was randomly selected; within each strip, a potential sample site was selected from the most representative landscape within the most common soil type. At one in four sites, duplicate samples were collected 10 meters apart to estimate local spatial variability. At each site, up to four separate soil samples were collected as follows: (1) material from 0-5 cm depth; (2) O horizon, if present; (3) a composite of the A horizon; and (4) C horizon. Each sample collected was analyzed for total major- and trace-element composition by the following methods: (1) inductively coupled plasmamass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICPAES) for aluminum, antimony, arsenic, barium, beryllium, bismuth, cadmium, calcium, cerium, cesium, chromium, cobalt, copper, gallium, indium, iron, lanthanum, lead, lithium, magnesium, manganese, molybdenum, nickel, niobium, phosphorus, potassium, rubidium, scandium, silver, sodium, strontium, sulfur, tellurium, thallium, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, and zinc; (2) cold vapor- atomic absorption spectrometry for mercury; (3) hydride generation-atomic absorption spectrometry for antimony and selenium; (4) coulometric titration for carbonate carbon; and (5) combustion for total carbon and total sulfur.

The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses.

PubMed

Irigoyen, Alejo J; Rojo, Irene; Calò, Antonio; Trobbiani, Gastón; Sánchez-Carnero, Noela; García-Charton, José A

2018-01-01

Underwater visual census (UVC) is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT), designed to maximize transect length (and thus the surveyed area) with respect to diving time invested in monitoring, as compared to Conventional Strip Transects (CST). Additionally, we analyze the effect of increasing transect width and length on the precision of density estimates by comparing TRT vs. CST methods using different fixed widths of 6 and 20 m (FW3 and FW10, respectively) and the Distance Sampling (DS) method, in which perpendicular distance of each fish or group of fishes to the transect line is estimated by divers up to 20 m from the transect line. The TRT was 74% more time and cost efficient than the CST (all transect widths considered together) and, for a given time, the use of TRT and/or increasing the transect width increased the precision of density estimates. In addition, since with the DS method distances of fishes to the transect line have to be estimated, and not measured directly as in terrestrial environments, errors in estimations of perpendicular distances can seriously affect DS density estimations. To assess the occurrence of distance estimation errors and their dependence on the observer's experience, a field experiment using wooden fish models was performed. We tested the precision and accuracy of density estimators based on fixed widths and the DS method. The accuracy of the estimates was measured comparing the actual total abundance with those estimated by divers using FW3, FW10, and DS estimators. Density estimates differed by 13% (range 0.1-31%) from the actual values (average = 13.09%; median = 14.16%). Based on our results we encourage the use of the Tracked Roaming Transect with Distance Sampling (TRT+DS) method for improving density estimates of species occurring at low densities and/or highly aggregated, as well as for exploratory rapid-assessment surveys in which divers could gather spatial ecological and ecosystem information on large areas during UVC.

The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses

PubMed Central

2018-01-01

Underwater visual census (UVC) is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT), designed to maximize transect length (and thus the surveyed area) with respect to diving time invested in monitoring, as compared to Conventional Strip Transects (CST). Additionally, we analyze the effect of increasing transect width and length on the precision of density estimates by comparing TRT vs. CST methods using different fixed widths of 6 and 20 m (FW3 and FW10, respectively) and the Distance Sampling (DS) method, in which perpendicular distance of each fish or group of fishes to the transect line is estimated by divers up to 20 m from the transect line. The TRT was 74% more time and cost efficient than the CST (all transect widths considered together) and, for a given time, the use of TRT and/or increasing the transect width increased the precision of density estimates. In addition, since with the DS method distances of fishes to the transect line have to be estimated, and not measured directly as in terrestrial environments, errors in estimations of perpendicular distances can seriously affect DS density estimations. To assess the occurrence of distance estimation errors and their dependence on the observer’s experience, a field experiment using wooden fish models was performed. We tested the precision and accuracy of density estimators based on fixed widths and the DS method. The accuracy of the estimates was measured comparing the actual total abundance with those estimated by divers using FW3, FW10, and DS estimators. Density estimates differed by 13% (range 0.1–31%) from the actual values (average = 13.09%; median = 14.16%). Based on our results we encourage the use of the Tracked Roaming Transect with Distance Sampling (TRT+DS) method for improving density estimates of species occurring at low densities and/or highly aggregated, as well as for exploratory rapid-assessment surveys in which divers could gather spatial ecological and ecosystem information on large areas during UVC. PMID:29324887

Carbon System Dynamics within the Papahānaumokuākea Marine National Monument

NASA Astrophysics Data System (ADS)

Kealoha, A. K.; Winn, C. D.; Kahng, S.; Alin, S. R.; Mackenzie, F. T.; Kosaki, R.

2013-12-01

Continuous underway measurements of atmospheric CO2, oceanic pCO2, pH, salinity, temperature, and oxygen were collected in surface waters within Papahānaumokuākea Marine National Monument (PMNM). Transects were conducted in the summers of 2011 and 2012 and encompassed the entire length of monument waters from approximately 21° to 28°N. Discrete samples were obtained from the underway system for the determination of spectrophotometric pH and titration alkalinity. The discrete pH samples were used to assess the consistency of the underway pH electrode and indicate that the electrode generated consistent and precise data over the duration of each cruise. The underway data collected over the entire transects show considerable variability in carbon parameters and reflects mainly the intense biological activity that occurs within coral reef ecosystems in and around the atolls comprising the Northwestern Hawaiian Archipelago. The impact of organic and inorganic metabolism on the carbon system in nearshore water was based primarily on measurements taken at French Frigate Shoals (FFS), where our most intense sampling occurred. For this analysis, all of the data collected within the area encompassed by the atoll and the surrounding ocean roughly 10 km from the 50-meter depth contour were included. These data, which span an approximate 300-km2 area, clearly show that nearshore metabolic processes influence surface water chemistry out to at least 10 km away from the shallow-water environment. Our data also show that, while the spatio-temporal complexities associated with analyzing underway data can complicate the interpretation of pCO2 and pH variability, an obvious diel trend in total alkalinity (TA) was apparent. In addition, plotting temporal changes in total dissolved inorganic carbon (DIC) and TA revealed the relative contributions of organic and inorganic metabolism to net reef metabolism.

Delineating high-density areas in spatial Poisson fields from strip-transect sampling using indicator geostatistics: application to unexploded ordnance removal.

PubMed

Saito, Hirotaka; McKenna, Sean A

2007-07-01

An approach for delineating high anomaly density areas within a mixture of two or more spatial Poisson fields based on limited sample data collected along strip transects was developed. All sampled anomalies were transformed to anomaly count data and indicator kriging was used to estimate the probability of exceeding a threshold value derived from the cdf of the background homogeneous Poisson field. The threshold value was determined so that the delineation of high-density areas was optimized. Additionally, a low-pass filter was applied to the transect data to enhance such segmentation. Example calculations were completed using a controlled military model site, in which accurate delineation of clusters of unexploded ordnance (UXO) was required for site cleanup.

A geostatistical approach for quantification of contaminant mass discharge uncertainty using multilevel sampler measurements

NASA Astrophysics Data System (ADS)

Li, K. Betty; Goovaerts, Pierre; Abriola, Linda M.

2007-06-01

Contaminant mass discharge across a control plane downstream of a dense nonaqueous phase liquid (DNAPL) source zone has great potential to serve as a metric for the assessment of the effectiveness of source zone treatment technologies and for the development of risk-based source-plume remediation strategies. However, too often the uncertainty of mass discharge estimated in the field is not accounted for in the analysis. In this paper, a geostatistical approach is proposed to estimate mass discharge and to quantify its associated uncertainty using multilevel transect measurements of contaminant concentration (C) and hydraulic conductivity (K). The approach adapts the p-field simulation algorithm to propagate and upscale the uncertainty of mass discharge from the local uncertainty models of C and K. Application of this methodology to numerically simulated transects shows that, with a regular sampling pattern, geostatistics can provide an accurate model of uncertainty for the transects that are associated with low levels of source mass removal (i.e., transects that have a large percentage of contaminated area). For high levels of mass removal (i.e., transects with a few hot spots and large areas of near-zero concentration), a total sampling area equivalent to 6˜7% of the transect is required to achieve accurate uncertainty modeling. A comparison of the results for different measurement supports indicates that samples taken with longer screen lengths may lead to less accurate models of mass discharge uncertainty. The quantification of mass discharge uncertainty, in the form of a probability distribution, will facilitate risk assessment associated with various remediation strategies.

Water-quality data for the Ohio River from New Cumberland Dam to Pike Island Dam, West Virginia and Ohio, May-October 1993

USGS Publications Warehouse

Miller, K.F.; Messinger, Terence; Waldron, M.C.; Faulkenburg, C.W.

1996-01-01

This report contains water-quality data for the Ohio River from river mile 51.1 (3.3 miles upstream from New Cumberland Dam) to river mile 84.0 (0.2 miles upstream from Pike Island Dam) that were collected during the summer and fall of 1993. The data were collected to establish the water quality of the Ohio River and to use in assessing the proposed effects of hydropower development on the water quality of the Ohio River. Water quality was determined by a combination of repeated synoptic field measurements, continuous-record monitoring, and laboratory analyses. Synoptic measurements were made along a longitudinal transect with 18 mid-channel sampling sites; cross-sectional transects of water-quality measurements were made at 5 of these sites. Water-quality measurements also were made at two sites located on the back-channel (Ohio) side of Browns Island. At each longitudinal-transect and back-channel sampling site, measurements were made of specific conductance, pH, water temperature, and dissolved oxygen conentration. Longitudinal-transect and back-channel stations were sampled at four depths (at the surface, about 3.3 feet below the surface, middle of the water column, and near the bottom of the river). Cross-sectional transects consisted of three to four detailed vertical profiles of the same characteristics. Water samples were collected from three depths at the mid-channel vertical profile in each cross-sectional transect and were analyzed for concentrations of phytoplankton photosynthetic pigments chlorophyll a and chlorophyll b. Estimates of the depth of light penetration (Secchi-disk transparency) were made at pigment-sampling locations whenever light and river-surface conditions were appropriate. Synoptic sampling usually was completed in 12 hours or less and was repeated 10 times from May through October 1993. Continuous-record monitoring of water quality consisted of hourly measurements of specific conductance, pH, water temperature, and dissolved oxygen concentration, made at a depth of 6.6 feet upstream and downstream of New Cumberland Dam. Continuous monitors were operated from May through October 1993.

Ecological effects of the harvest phase of geoduck clam (Panopea generosa Gould, 1850) aquaculture on infaunal communities in southern Puget Sound, Washington USA.

USGS Publications Warehouse

VanBlaricom, Glenn R.; Eccles, Jennifer L.; Olden, Julian D.; Mcdonald, P. Sean

2015-01-01

Intertidal aquaculture for geoducks (Panopea generosa Gould, 1850) is expanding in southern Puget Sound, Washington, where gently sloping sandy beaches are used for field culture. Geoduck aquaculture contributes significantly to the regional economy, but has become controversial because of a range of unresolved questions involving potential biological impacts on marine ecosystems. From 2008 through 2012, the authors used a “before-after-control-impact” experimental design, emphasizing spatial scales comparable with those used by geoduck culturists to evaluate the effects of harvesting market-ready geoducks on associated benthic infaunal communities. Infauna were sampled at three different study locations in southern Puget Sound at monthly intervals before, during, and after harvests of clams, and along extralimital transects extending away from the edges of cultured plots to assess the effects of harvest activities in adjacent uncultured habitat. Using multivariate statistical approaches, strong seasonal and spatial signals in patterns of abundance were found, but there was scant evidence of effects on the community structure associated with geoduck harvest disturbances within cultured plots. Likewise, no indications of significant “spillover” effects of harvest on uncultured habitat adjacent to cultured plots were noted. Complementary univariate approaches revealed little evidence of harvest effects on infaunal biodiversity and indications of modest effects on populations of individual infaunal taxa. Of 10 common taxa analyzed, only three showed evidence of reduced densities, although minor, after harvests whereas the remaining seven taxa indicated either neutral responses to harvest disturbances or increased abundance either during or in the months after harvest events. It is suggested that a relatively active natural disturbance regime, including both small-scale and large-scale events that occur with comparable intensity but more frequently than geoduck harvest events in cultured plots, has facilitated assemblage-level infaunal resistance and resilience to harvest disturbances.

Evaluation of line transect sampling based on remotely sensed data from underwater video

USGS Publications Warehouse

Bergstedt, R.A.; Anderson, D.R.

1990-01-01

We used underwater video in conjunction with the line transect method and a Fourier series estimator to make 13 independent estimates of the density of known populations of bricks lying on the bottom in shallows of Lake Huron. The pooled estimate of density (95.5 bricks per hectare) was close to the true density (89.8 per hectare), and there was no evidence of bias. Confidence intervals for the individual estimates included the true density 85% of the time instead of the nominal 95%. Our results suggest that reliable estimates of the density of objects on a lake bed can be obtained by the use of remote sensing and line transect sampling theory.

Benthic macroinvertebrate field sampling effort required to ...

EPA Pesticide Factsheets

This multi-year pilot study evaluated a proposed field method for its effectiveness in the collection of a benthic macroinvertebrate sample adequate for use in the condition assessment of streams and rivers in the Neuquén Province, Argentina. A total of 13 sites, distributed across three rivers, were sampled. At each site, benthic macroinvertebrates were collected at 11 transects. Each sample was processed independently in the field and laboratory. Based on a literature review and resource considerations, the collection of 300 organisms (minimum) at each site was determined to be necessary to support a robust condition assessment, and therefore, selected as the criterion for judging the adequacy of the method. This targeted number of organisms was collected at all sites, at a minimum, when collections from all 11 transects were combined. Subsequent bootstrapping analysis of data was used to estimate whether collecting at fewer transects would reach the minimum target number of organisms for all sites. In a subset of sites, the total number of organisms frequently fell below the target when fewer than 11 transects collections were combined.Site conditions where <300 organisms might be collected are discussed. These preliminary results suggest that the proposed field method results in a sample that is adequate for robust condition assessment of the rivers and streams of interest. When data become available from a broader range of sites, the adequacy of the field

Statistical methods for identifying and bounding a UXO target area or minefield

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

McKinstry, Craig A.; Pulsipher, Brent A.; Gilbert, Richard O.

2003-09-18

The sampling unit for minefield or UXO area characterization is typically represented by a geographical block or transect swath that lends itself to characterization by geophysical instrumentation such as mobile sensor arrays. New spatially based statistical survey methods and tools, more appropriate for these unique sampling units have been developed and implemented at PNNL (Visual Sample Plan software, ver. 2.0) with support from the US Department of Defense. Though originally developed to support UXO detection and removal efforts, these tools may also be used in current form or adapted to support demining efforts and aid in the development of newmore » sensors and detection technologies by explicitly incorporating both sampling and detection error in performance assessments. These tools may be used to (1) determine transect designs for detecting and bounding target areas of critical size, shape, and density of detectable items of interest with a specified confidence probability, (2) evaluate the probability that target areas of a specified size, shape and density have not been missed by a systematic or meandering transect survey, and (3) support post-removal verification by calculating the number of transects required to achieve a specified confidence probability that no UXO or mines have been missed.« less

Stable isotope differences among the Lake Michigan 2015 CSMI transects

EPA Science Inventory

During the Lake Michigan 2015 Cooperative Science and Monitoring Initiative (CSMI), eight transects situated near tributaries that present a gradient of phosphorus loads were sampled from nearshore to offshore during May, July, and September. Our objective was to evaluate associa...

Remote sensing with simulated unmanned aircraft imagery for precision agriculture applications

USGS Publications Warehouse

Hunt, E. Raymond; Daughtry, Craig S.T.; Mirsky, Steven B.; Hively, W. Dean

2014-01-01

An important application of unmanned aircraft systems (UAS) may be remote-sensing for precision agriculture, because of its ability to acquire images with very small pixel sizes from low altitude flights. The objective of this study was to compare information obtained from two different pixel sizes, one about a meter (the size of a small vegetation plot) and one about a millimeter. Cereal rye (Secale cereale) was planted at the Beltsville Agricultural Research Center for a winter cover crop with fall and spring fertilizer applications, which produced differences in biomass and leaf chlorophyll content. UAS imagery was simulated by placing a Fuji IS-Pro UVIR digital camera at 3-m height looking nadir. An external UV-IR cut filter was used to acquire true-color images; an external red cut filter was used to obtain color-infrared-like images with bands at near-infrared, green, and blue wavelengths. Plot-scale Green Normalized Difference Vegetation Index was correlated with dry aboveground biomass ( ${mbi {r}} = 0.58$ ), whereas the Triangular Greenness Index (TGI) was not correlated with chlorophyll content. We used the SamplePoint program to select 100 pixels systematically; we visually identified the cover type and acquired the digital numbers. The number of rye pixels in each image was better correlated with biomass ( ${mbi {r}} = 0.73$ ), and the average TGI from only leaf pixels was negatively correlated with chlorophyll content ( ${mbi {r}} = -0.72$ ). Thus, better information for crop requirements may be obtained using very small pixel sizes, but new algorithms based on computer vision are needed for analysis. It may not be necessary to geospatially register large numbers of photographs with very small pixel sizes. Instead, images could be analyzed as single plots along field transects.

Evaluation of Bare Ground on Rangelands using Unmanned Aerial Vehicles

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

Robert P. Breckenridge; Maxine Dakins

2011-01-01

Attention is currently being given to methods that assess the ecological condition of rangelands throughout the United States. There are a number of different indicators that assess ecological condition of rangelands. Bare Ground is being considered by a number of agencies and resource specialists as a lead indicator that can be evaluated over a broad area. Traditional methods of measuring bare ground rely on field technicians collecting data along a line transect or from a plot. Unmanned aerial vehicles (UAVs) provide an alternative to collecting field data, can monitor a large area in a relative short period of time, andmore » in many cases can enhance safety and time required to collect data. In this study, both fixed wing and helicopter UAVs were used to measure bare ground in a sagebrush steppe ecosystem. The data were collected with digital imagery and read using the image analysis software SamplePoint. The approach was tested over seven different plots and compared against traditional field methods to evaluate accuracy for assessing bare ground. The field plots were located on the Idaho National Laboratory (INL) site west of Idaho Falls, Idaho in locations where there is very little disturbance by humans and the area is grazed only by wildlife. The comparison of fixed-wing and helicopter UAV technology against field estimates shows good agreement for the measurement of bare ground. This study shows that if a high degree of detail and data accuracy is desired, then a helicopter UAV may be a good platform. If the data collection objective is to assess broad-scale landscape level changes, then the collection of imagery with a fixed-wing system is probably more appropriate.« less

Modeling abundance using hierarchical distance sampling

USGS Publications Warehouse

Royle, Andy; Kery, Marc

2016-01-01

In this chapter, we provide an introduction to classical distance sampling ideas for point and line transect data, and for continuous and binned distance data. We introduce the conditional and the full likelihood, and we discuss Bayesian analysis of these models in BUGS using the idea of data augmentation, which we discussed in Chapter 7. We then extend the basic ideas to the problem of hierarchical distance sampling (HDS), where we have multiple point or transect sample units in space (or possibly in time). The benefit of HDS in practice is that it allows us to directly model spatial variation in population size among these sample units. This is a preeminent concern of most field studies that use distance sampling methods, but it is not a problem that has received much attention in the literature. We show how to analyze HDS models in both the unmarked package and in the BUGS language for point and line transects, and for continuous and binned distance data. We provide a case study of HDS applied to a survey of the island scrub-jay on Santa Cruz Island, California.

Investigation of Soil Erosion and Phosphorus Transport within an Agricultural Watershed

NASA Astrophysics Data System (ADS)

Klik, A.; Jester, W.; Muhar, A.; Peinsitt, A.; Rampazzo, N.; Mentler, A.; Staudinger, B.; Eder, M.

2003-04-01

In a 40 ha agricultural used watershed in Austria, surface runoff, soil erosion and nutrient losses are measured spatially distributed with 12 small erosion plots. Crops during growing season 2002 are canola, corn, sunflower, winter wheat, winter barley, rye, sugar beets, and pasture. Canopy height and canopy cover are observed in 14-day intervals. Four times per year soil water content, shear stress and random roughness of the surface are measured in a 25 x 25 m grid (140 points). The same raster is sampled for soil texture analyses and content of different phosphorus fractions in the 0-10 cm soil depth. Spatially distributed data are used for geostatistical analysis. Along three transects hydrologic conditions of the hillslope position (top, middle, foot) are investigated by measuring soil water content and soil matrix potential. After erosive events erosion features (rills, deposition, ...) are mapped using GPS. All measured data will be used as input parameters for the Limburg Soil Erosion Model (LISEM).

Uranium isotopes in tree bark as a spatial tracer of environmental contamination near former uranium processing facilities in southwest Ohio.

PubMed

Conte, Elise; Widom, Elisabeth; Kuentz, David

2017-11-01

Inappropriate handling of radioactive waste at nuclear facilities can introduce non-natural uranium (U) into the environment via the air or groundwater, leading to anthropogenic increases in U concentrations. Uranium isotopic analyses of natural materials (e.g. soil, plants or water) provide a means to distinguish between natural and anthropogenic U in areas near sources of radionuclides to the environment. This study examines the utility of two different tree bark transects for resolving the areal extent of U atmospheric contamination using several locations in southwest Ohio that historically processed U. This study is the first to utilize tree bark sampling transects to assess environmental contamination emanating from a nuclear facility. The former Fernald Feed Materials Production Center (FFMPC; Ross, Ohio) produced U metal from natural U ores and recycled nuclear materials from 1951 to 1989. Alba Craft Laboratory (Oxford, Ohio) machined several hundred tons of natural U metal from the FFMPC between 1952 and 1957. The Herring-Hall-Marvin Safe Company (HHM; Hamilton, Ohio) intermittently fabricated slugs rolled from natural U metal stock for use in nuclear reactors from 1943 to 1951. We have measured U concentrations and isotope signatures in tree bark sampled along an ∼35 km SSE-NNW transect from the former FFMPC to the vicinity of the former Alba Craft laboratories (transect #1) and an ∼20 km SW- NE (prevailing local wind direction) transect from the FFMPC to the vicinity of the former HHM (transect #2), with a focus on old trees with thick, persistent bark that could potentially record a time-integrated signature of environmental releases of U related to anthropogenic activity. Our results demonstrate the presence of anthropogenic U contamination in tree bark from the entire study area in both transects, with U concentrations within 1 km of the FFMPC up to ∼400 times local background levels of 0.066 ppm. Tree bark samples from the Alba Craft and HHM transects exhibit increasing U concentrations within ∼5 and ∼10 km, respectively of the FFMPC. The 236 U/ 238 U isotopic ratios in tree bark from both transects increase progressively towards the FFMPC with values as high as 2.00 × 10 -4  at the FFMPC. Tree bark sampled within 1 km of the FFMPC exhibits clear evidence for both enriched and depleted uranium with 235 U/ 238 U values from 0.00461 to 0.00736, with 234 U/ 238 U activity ratio ranging from 0.53 to 0.96, and 236 U/ 238 U from 6.05 × 10 -5 to 1.05 × 10 -4 . Tree bark from transect #1 between 1 and 30 km from the FFMPC exhibits depleted and natural 235 U/ 238 U values ranging from 0.00552 to 0.00726 [ 234 U/ 238 U activity ratio: 0.69-1.04; 236 U/ 238 U: 2.49 × 10 -6 - 2.00 × 10 -4 ]. Tree bark from transect #2 sampled between 1 and ∼20 km away from the FFMPC exhibits evidence of enriched and depleted U in the environment with 235 U/ 238 U ranging from 0.00635 to 0.00738 [ 234 U/ 238 U activity ratio: 0.83-0.98; 236 U/ 238 U: 1.43 × 10 -5 - 2.00 × 10 -4 ]. Results from scanning electron microscopy with energy dispersive spectrometry provides evidence for U-rich particles as the source of contamination found in tree bark growing within 1-3 km of the former FFMPC. Such observations are consistent with the previously observed 14 μm U-rich particle identified in tree bark sampled within 1 km of the FFMPC (Conte et al., 2015). Overall, this study shows the usefulness of a tree bark sample transect to assess the areal extent of atmospheric contaminant U stemming from nuclear facilities. Copyright © 2017 Elsevier Ltd. All rights reserved.

NATURAL ATTENUATION OF MTBE

EPA Science Inventory

For the case studies, the MTBE, TBA, and BTEX plume will be studied in a longitudinal transect along the center-line of the plume, and at least two transects perpendicular to ground water flow. Water samples will be analyzed for the concentration of MTBE, TBA, BTEX, methane, sulf...

NGEE Arctic Plant Traits: Shrub Transects, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, 2016

DOE Data Explorer

Verity Salmon; Colleen Iversen; Peter Thornton; Ma

2017-03-01

Transect data is from point center quarter surveys for shrub density performed in July 2016 at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. For each sample point along the transects, moving averages for shrub density and shrub basal area are provided along with GPS coordinates, average shrub height and active layer depth. The individual height, basal area, and species of surveyed shrubs are also included. Data upload will be completed January 2017.

Evaluation of fire as a management tool for controlling Schinus terebinthifolius as secondary successional growth on abandoned agricultural land

NASA Astrophysics Data System (ADS)

Doren, Robert F.; Whiteaker, Louis D.; Larosa, Anne Marie

1991-01-01

Schinus terebinthifolius, native to South America, has become an aggressive woody weed in southern Florida, displacing native vegetation as well as rapidly invading disturbed sites. Studies to evaluate the effectiveness of fire as a management option for controlling Schinus on abandoned farmland in Everglades National Park, known as the “Hole-in-the-Donut,” began in 1979. Study plots were established to monitor any change(s) in herbaceous cover and in numbers and size of Schinus stems. Except in the control plot (which was not burned), each site was burned as often as fuel conditions permitted (usually once every one or two years), through 1985. Results indicated that both the number and density of Schinus stems increased over the course of the study. While plots that burned showed a reduction in the rate of Schinus invasion, invasion still progressed rapidly with or without the occurrence of fire. The increase in Schinus stem density from 1980 to 1985 was highly significant in all transects except one. Herbaceous cover showed no clear trends relative to burning.

Field-based evaluations of sampling techniques to support long-term monitoring of riparian ecosystems along wadeable streams on the Colorado Plateau

USGS Publications Warehouse

Scott, Michael L.; Reynolds, Elizabeth W.

2007-01-01

Compared to 5-m by 20-m tree quadrats, belt transects were shown to provide similar estimates of stand structure (stem density and stand basal area) in less than 30 percent of the time. Further, for the streams sampled, there were no statistically significant differences in stem density and basal area estimates between 10-m and 20-m belt transects and the smaller belts took approximately half the time to sample. There was, however, high variance associated with estimates of stand structure for infrequently occurring stems, such as large, relict or legacy riparian trees. Legacy riparian trees occurred in limited numbers at all sites sampled. A reachscale population census of these trees indicated that the 10-m belt transects tended to underestimate both stem density and basal area for these riparian forest elements and that a complete reach-scale census of legacy trees averaged less than one hour per site.

Methodology for Augmenting Existing Paths with Additional Parallel Transects

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

Wilson, John E.

2013-09-30

Visual Sample Plan (VSP) is sample planning software that is used, among other purposes, to plan transect sampling paths to detect areas that were potentially used for munition training. This module was developed for application on a large site where existing roads and trails were to be used as primary sampling paths. Gap areas between these primary paths needed to found and covered with parallel transect paths. These gap areas represent areas on the site that are more than a specified distance from a primary path. These added parallel paths needed to optionally be connected together into a single path—themore » shortest path possible. The paths also needed to optionally be attached to existing primary paths, again with the shortest possible path. Finally, the process must be repeatable and predictable so that the same inputs (primary paths, specified distance, and path options) will result in the same set of new paths every time. This methodology was developed to meet those specifications.« less

Design of a factorial experiment with randomization restrictions to assess medical device performance on vascular tissue

PubMed Central

2011-01-01

Background Energy-based surgical scalpels are designed to efficiently transect and seal blood vessels using thermal energy to promote protein denaturation and coagulation. Assessment and design improvement of ultrasonic scalpel performance relies on both in vivo and ex vivo testing. The objective of this work was to design and implement a robust, experimental test matrix with randomization restrictions and predictive statistical power, which allowed for identification of those experimental variables that may affect the quality of the seal obtained ex vivo. Methods The design of the experiment included three factors: temperature (two levels); the type of solution used to perfuse the artery during transection (three types); and artery type (two types) resulting in a total of twelve possible treatment combinations. Burst pressures of porcine carotid and renal arteries sealed ex vivo were assigned as the response variable. Results The experimental test matrix was designed and carried out as a split-plot experiment in order to assess the contributions of several variables and their interactions while accounting for randomization restrictions present in the experimental setup. The statistical software package SAS was utilized and PROC MIXED was used to account for the randomization restrictions in the split-plot design. The combination of temperature, solution, and vessel type had a statistically significant impact on seal quality. Conclusions The design and implementation of a split-plot experimental test-matrix provided a mechanism for addressing the existing technical randomization restrictions of ex vivo ultrasonic scalpel performance testing, while preserving the ability to examine the potential effects of independent factors or variables. This method for generating the experimental design and the statistical analyses of the resulting data are adaptable to a wide variety of experimental problems involving large-scale tissue-based studies of medical or experimental device efficacy and performance. PMID:21599963

A new field method to characterise the runoff generation potential of burned hillslopes

NASA Astrophysics Data System (ADS)

Sheridan, Gary; Lane, Patrick; Langhans, Christoph

2016-04-01

The prediction of post fire runoff generation is critical for the estimation of post fire erosion processes and rates. Typical field measures for determining infiltration model parameters include ring infiltrometers, tension infiltrometers, rainfall simulators and natural runoff plots. However predicting the runoff generating potential of post-fire hillslopes is difficult due to the high spatial variability of soil properties relative to the size of the measurement method, the poorly understood relationship between water repellence and runoff generation, known scaling issues with all the above hydraulic measurements, and logistical limitations for measurements in remote environments. In this study we tested a new field method for characterizing surface runoff generation potential that overcomes these limitations and is quick, simple and cheap to apply in the field. The new field method involves the manual application of a 40mm depth of Brilliant Blue FCF food dye along a 10cm wide and 5m long transect along the contour under slightly-ponded conditions. After 24 hours the transect is excavated to a depth of 10cm and the percentage dyed area within the soil profile recorded manually. The dyed area is an index of infiltration potential of the soil during intense rainfall events, and captures both spatial variability and water repellence effects. The dye measurements were made adjacent to long term instrumented post fire rainfall-runoff plots on 7 contrasting soil types over a 6 month period, and the results show surprisingly strong correlations (r2 = 0.9) between the runoff-ratio from the plots and the dyed area. The results are used to develop an initial conceptual model that links the dye index with an infiltration model and parameters suited to burnt hillslopes. The capacity of this method to provide a simple, and reliable indicator of post fire runoff potential from different fire severities, soil types and treatments is explored in this presentation.

Continental-scale patterns in soil geochemistry and mineralogy: results from two transects across the United States and Canada

USGS Publications Warehouse

Woodruff, L.G.; Cannon, W.F.; Eberl, D.D.; Smith, D.B.; Kilburn, J.E.; Horton, J.D.; Garrett, R.G.; Klassen, R.A.

2009-01-01

In 2004, the US Geological Survey (USGS) and the Geological Survey of Canada (GSC) initiated a pilot study that involved collection of more than 1500 soil samples from 221 sites along two continental transects across Canada and the United States. The pilot study was designed to test and refine protocols for a soil geochemical survey of North America. The two transects crossed a wide array of soil parent materials, soil ages, climatic conditions, landforms, land covers and land uses. Sample sites were selected randomly at approximately 40-km intervals from a population defined as all soils of the continent. At each site, soils representing 0 to 5 cm depth, and the O, A, and C horizons, if present, were collected and analyzed for their near-total content of over 40 major and trace elements. Soils from 0–5 cm depth were also collected for analysis of organic compounds. Results from the transects confirm that soil samples collected at a 40-km spacing reveal coherent, continental- to subcontinental-scale geochemical and mineralogical patterns that can be correlated to aspects of underlying soil parent material, soil age and climate influence. The geochemical data also demonstrate that at the continental-scale the dominance of any of these major factors that control soil geochemistry can change across the landscape. Along both transects, soil mineralogy and geochemistry change abruptly with changes in soil parent materials. However, the chemical influence of a soil’s parent material can be obscured by changing climatic conditions. For the transects, increasing precipitation from west to east and increasing temperature from north to south affect both soil mineralogy and geochemistry because of climate effects on soil weathering and leaching, and plant productivity. Regional anomalous metal concentrations can be linked to natural variations in soil parent materials, such as high Ni and Cr in soils developed on ultramafic rocks in California or high P in soils formed on weathered Ordovician limestones in central Kentucky. On local scales, anomalous metal concentrations recognized in soil profiles, such as high P in soils from animal confinement sites, are consistent with local anthropogenic disturbances. At a larger scale, the distribution of Hg across the west to east transect demonstrates that it can be difficult to distinguish between natural or anthropogenic contributions and that many factors can contribute to an element’s spatial distribution. Only three samples in a subset of seventy-three 0–5 cm depth soil samples from the north to south transect had organochlorine pesticides values above the method detection limit, apparently related to historic usage of the pesticides DDT and dieldrin.

The effect of vegetation type, microrelief, and incidence angle on radar backscatter

NASA Technical Reports Server (NTRS)

Owe, M.; Oneill, P. E.; Jackson, T. J.; Schmugge, T. J.

1985-01-01

The NASA/JPL Synthetic Aperture Radar (SAR) was flown over a 20 x 110 km test site in the Texas High Plains regions north of Lubbock during February/March 1984. The effect of incidence angle was investigated by comparing the pixel values of the calibrated and uncalibrated images. Ten-pixel-wide transects along the entire azimuth were averaged in each of the two scenes, and plotted against the calculated incidence angle of the center of each range increment. It is evident from the graphs that both the magnitudes and patterns exhibited by the corresponding transect means of the two images are highly dissimilar. For each of the cross-poles, the uncalibrated image displayed very distinct and systematic positive trends through the entire range of incidence angles. The two like-poles, however, exhibited relatively constant returns. In the calibrated image, the cross-poles exhibited a constant return, while the like-poles demonstrated a strong negative trend across the range of look-angles, as might be expected.

Batrachochytrium dendrobatidis infection patterns among Panamanian amphibian species, habitats and elevations during epizootic and enzootic stages.

PubMed

Brem, Forrest M R; Lips, Karen R

2008-09-24

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has caused declines of many amphibian populations, yet the full course of the epizootic has rarely been observed in wild populations. We determined effects of elevation, habitat, and aquatic index (AI) on prevalence of infection among Panamanian amphibians sampled along 2 elevational transects. Amphibian populations on the Santa Fé transect (SFT) had declined in 2002, while those on the El Copé transect (ECT) were healthy until September 2004. In 2004 we sampled Bd along both transects, surveying the SFT 2 yr after decline, and surveying the ECT 4 mo prior to the arrival of Bd, during the epizootic, and 2 mo later. Overall prevalence of Bd along the ECT increased from 0.0 (95% CI 0.00-0.0003) to 0.51 (95% CI 0.48-0.55) over a 3 mo period, accompanied by significant decreases in amphibian abundance and species richness in all habitats. Prevalence of infection on the ECT was highest along riparian transects and at higher elevations, but not among levels of AI. Prevalence of infection on the SFT was highest in pool transects, and at higher elevations, but not among levels of AI. Riparian amphibian abundance and species richness also declined at SFT following detection of Bd in 2002. Variation among species, microenvironmental conditions, and the length of coexistence with Bd may contribute to observed differences in prevalence of Bd and in population response.

AMPHIPOD COMMUNITY RESPONSE TO STRESS INDUCED BY ALGAL MATS IN A PACIFIC NORTHWEST ESTUARY

EPA Science Inventory

Amphipod, algal and sediment samples were taken at two- to four-week intervals from June through December, 2000 along two transects in Yaquina Bay, OR. The transects extended from within the Zostera marina bed at the river channel edge through intertidal burrowing shrimp ...

The design of sampling transects for characterizing water quality in estuaries

USGS Publications Warehouse

Jassby, A.D.; Cole, B.E.; Cloern, J.E.

1997-01-01

The high spatial variability of estuaries poses a challenge for characterizing estuarine water quality. This problem was examined by conducting monthly high-resolution transects for several water quality variables (chlorophyll a, suspended particulate matter and salinity) in San Francisco Bay (California, U.S.A.). Using these data, six different ways of choosing station locations along a transect, in order to estimate mean conditions, were compared. In addition, 11 approaches to estimating the variance of the transect mean when stations are equally spaced were compared, and the relationship between variance of the estimated transect mean and number of stations was determined. The results provide guidelines for sampling along the axis of an estuary: (1) Choose as many equally-spaced stations as practical; (2) estimate the variance of the mean y?? by var (y??)=(1/10n2)??(j=2)/(n) (y(j)-y(j-1)2, where y1,...,y(n) are the measurements at the n stations; and (3) attain the desired precision by adjusting the number of stations according to var(y??)???1/n2. The inverse power of 2 in the last step is a consequence of the underlying spatial correlation structure in San Francisco Bay; more studies of spatial structure at other estuaries are needed to determine the generality of this relationship.

Key seabird areas in southern New England identified using a community occupancy model

USGS Publications Warehouse

O'Connell, Allan F.; Flanders, Nicholas P.; Gardner, Beth; Winiarski, Kristopher J.; Paton, Peter W. C.; Allison, Taber

2015-01-01

Seabirds are of conservation concern, and as new potential risks to seabirds are arising, the need to provide unbiased estimates of species’ distributions is growing. We applied community occupancy models to detection/non-detection data collected from repeated aerial strip-transect surveys conducted in 2 large study plots off southern New England, USA; one off the coast of Rhode Island and the other in Nantucket Sound. A total of 17 seabird species were observed at least once in each study plot. We found that detection varied by survey date and effort for most species and the average detection probability across species was less than 0.4. We estimated the influence of water depth, sea surface temperature, and sea surface chl a concentration on species-specific occupancy. Diving species showed large differences between the 2 study plots in their predicted winter distributions, which were largely explained by water depth acting as a stronger predictor of occupancy in Rhode Island than in Nantucket Sound. Conversely, similarities between the 2 study plots in predicted winter distributions of surface-feeding species were explained by sea surface temperature or chlorophyll a concentration acting as predictors of these species’ occupancy in both study plots. We predicted the number of species at each site using the observed data in order to detect ‘hot-spots’ of seabird diversity and use in the 2 study plots. These results provide new information on detection of species, areas of use, and relationships with environmental variables that will be valuable for biologists and planners interested in seabird conservation in the region.

The preglacial sediment record of Lake Ladoga, Russia - first results from a seismic survey and sediment coring in 2013

NASA Astrophysics Data System (ADS)

Melles, Martin; Krastel, Sebastian; Fedorov, Grigory; Subetto, Dmitry A.; Savelieva, Larisa A.; Andreev, Andrej; Wagner, Bernd

2014-05-01

The new German-Russian project PLOT (Paleolimnological Transect) aims at investigating the Late Quaternary climatic and environmental history along a more than 6000 km long longitudinal transect crossing northern Eurasia. Special emphasis is put on the preglacial history. For this purpose shallow and deep seismic surveys shall be carried out on five lakes, which potentially host preglacial sediment records, followed by sediment coring based on the results of the seismic campaigns. The well-studied Lake El'gygytgyn represents the eastern-most location of the transect and acts as reference site. Within the scope of a pilot phase for the PLOT project, funded by the German Federal Ministry of Education and Research, we were able to investigate Lake Ladoga, which is located close to St. Petersburg at the western end of the transect. Lake Ladoga is the largest lake in Europe, covering an area of almost 18.000 km2. The modern sedimentation as well as the late glacial and Holocene history of the lake were already studied in detail over the past decades. The older, preglacial lake history, however, is only rudimentary known from a core transect drilled in the southern lake in the 1930th. The cores of up to about 60 m length were only briefly described and are not existing any more. The results from these cores, known from unpublished reports only, suggest the existence of marine sediments of presumably Eemian age, representing a time when Lake Lagoga was part of a precursor of the Baltic Sea, which had a connection via Ladoga and Onega Lakes to the White Sea and further to the Arctic Ocean. In late August/early September 2013 we carried out a seismic survey on Lake Ladoga using a Mini-GI-Gun and a 32-channel seismic streamer. In total, 1500 km of seismic profiles were measured, covering most parts of the lake. The seismic lines typically show acoustically well stratified Holocene muds overlaying rather transparent postglacial varves. These sediment successions can reach more than 10 m in thickness. They usually are bordered by a hard reflector underneath that may represent coarse-grained sediments or a till, which in most areas is not penetrated by the acoustic waves. In particular in the western part of the lake, however, these sediment successions can be underlain by sedimentary strata of up to 60 m thickness that fill steeply sloped depressions or channels. Sediment coring at two sites in western Ladoga Lake confirmed the seismic interpretation of the postglacial sediment succession. At one of these sites, the basal reflector at about 13 m depth was penetrated another ca. 10 m into preglacial sediments. According to initial pollen data, these sediments were formed during an interglacial with a slightly warmer climate than that of the Holocene. Further work is currently carried out, for instance, to identify which of the Quaternary interglacials is respresented by the sediments cored in 2013.

Ground and surface water quality along a dambo transect in Chihota smallholder farming area, Marondera district, Zimbabwe

NASA Astrophysics Data System (ADS)

Wuta, M.; Nyamadzawo, G.; Mlambo, J.; Nyamugafata, P.

2016-04-01

In many smallholder farms in sub-Saharan Africa dambos are used for grazing and crop production especially horticultural crops. Increased use of dambos especially for crop production can result in ground and surface water pollution. Ground and surface water quality along a dambo transect in Chihota, Zimbabwe, was investigated between October 2013 and February 2014. The transect was divided into; upland (control), dambo gardens (mid-slope) and the river (valley bottom). Water samples for quality assessment were collected in October 2013 (peak of dry season) and February 2014 (peak of rainy season). The collected water samples were analysed for pH, faecal coliforms, total nitrogen, electrical conductivity, total dissolved solids (TDS), and some selected nutrients (P, K, Ca, Mg, Na, Zn, and Cu). Water pH was 7.0, 6.4 and 6.1 for river water, garden and upland wells respectively. During the wet season total nitrogen (TN) concentrations were 233 mg/L for uplands, 242 mg/L for gardens and 141 mg/L for the river. During the dry season, TN concentrations were all below 20 mg/L, and were not significantly different among sampling stations along the dambo transect. Dry season faecal coliform units (fcu) were significantly different and were 37.2, 30.0 and 5.0 for upland wells, garden wells and river respectively. Wet season faecal coliforms were also significantly different and were 428.5, 258.0 and 479.4 fcu for upland wells, garden wells and river respectively. The other measured physico-chemical parameters also varied with sampling position along the transect. It was concluded that TN and fcu in sampled water varied with season and that wet season concentrations were significantly higher than dry season concentrations. High concentrations of faecal coliforms and total N during the wet season was attributed to increased water movement. Water from upland wells, garden wells and river was not suitable for human consumption according to WHO standards during both the dry and wet seasons.

Detection and distribution of Tris(2-chloroethyl) phosphate on the East Antarctic ice sheet.

PubMed

Cheng, Wenhan; Sun, Liguang; Huang, Wen; Ruan, Ting; Xie, Zhouqing; Zhang, Pengfei; Ding, Rui; Li, Ming

2013-08-01

Use of PBDEs (Polybrominated Diphenyl Ethers) has been restricted in Europe and North America in recent years. As substitute products with similar properties, OPEs (Organophosphate Esters) are now used as alternatives to PBDEs. Recent research has revealed that, similar to PBDEs, OPEs are also environmentally hazardous like PBDEs. Thus knowledge of their distribution and transport is needed to understand the extent of risk. However, studies on environmental OPEs mainly focus on Europe and North America. Knowledge in the southern hemisphere is very limited. In this study, we analyzed fresh snow samples collected along the transect from Zhongshan Station to Kunlun Station, East Antarctica. Several OPEs were detected in this transect, among which Tris(2-chloroethyl) phosphate (TCEP) had the highest frequency of quantification. It was quantified in most samples from the coastal half of the transect and was detected but not quantified in most samples in the inland half. We show that TCEP at this transect probably originated from the ocean around Antarctica. This study is the first to report the presence of TCEP on the Antarctica ice sheet, providing evidence of its long range transport from the source regions. This work also indicate that TCEP can transport hundreds of kilometers in the Antarctica. Copyright © 2013 Elsevier Ltd. All rights reserved.

Adaptation of rhizome connections in drylands: increasing tolerance of clones to wind erosion.

PubMed

Yu, Fei-Hai; Wang, Ning; He, Wei-Ming; Chu, Yu; Dong, Ming

2008-10-01

Wind erosion is a severe stress for plants in drylands, but the mechanisms by which plants withstand erosion remain largely unknown. Here, the hypothesis is tested that maintaining rhizome connections helps plants to tolerate erosion. Five transects were established across an inland dune in Inner Mongolia, China, and measurements were made of leaf number, biomass per ramet and rhizome depth of Psammochloa villosa in 45 plots. In 40 x 40 cm plots of P. villosa on another dune, the top 15 or 30 cm of sand was removed for 1.5 or 3 months to simulate short- and long-term moderate and severe erosion, respectively, with untreated plots as controls, and the rhizomes at the edges of half of the plots were severed to mimic loss of rhizome connections. Leaf number and biomass per ramet showed quadric relationships with rhizome depth; when rhizomes were exposed to the air, the associated ramets either died or became very weak. Ramet number, leaf number and biomass per plot decreased with increasing erosion severity. Rhizome connections did not affect these traits under control or short-term erosion, but increased them under long-term erosion. Rhizome connections alleviated the negative effects of erosion on P. villosa, very likely because the erosion-stressed ramets received water and/or photosynthates translocated from those connected ramets that were not subject to erosion. This study provides the first evidence that maintaining rhizome connections helps plants to tolerate erosion in drylands.

Impacts of rewetting on hydrological functioning and dissolved organic carbon flux in a degraded peatland (La Guette, France)

NASA Astrophysics Data System (ADS)

Bernard-Jannin, Léonard; Binet, Stéphane; Gogo, Sébastien; Lemoing, Franck; Zocatelli, Renata; Jozja, Nevila; Défarge, Christian; Laggoun-Défarge, Fatima

2016-04-01

In Sphagnum-dominated peatlands, dissolved organic carbon (DOC) fluxes are mainly controlled by peat water saturation state corresponding to the equilibrium between recharge/drainage fluxes and to the peat storage capacity. Rewetting is a wide spread method that has been used for restoring the global hydrological behavior of degraded peatland ecosystems. Therefore, there is a need to assess the impact of rewetting on peatland hydrology but also on the modification of dynamics and DOC fluxes that significantly impact on carbon sink function of these ecosystems. To investigate this question, meteorology, hydrological data, DOC concentrations and dissolved organic matter (DOM) quality (aromaticity and fluorescence) were monthly monitored at the watershed scales and in two piezometer transects since 2010 in a hydrologically disturbed peatland, La Guette, which experienced a rewetting action on February 2014. One piezometer transect (called downstream plots) was supposedly influenced by the hydrological restoration while the other (called upstream plots) was considered as a control. Collected data allowed studying the impact of the restoration on hydrology and dynamics and DOC fluxes in the peatland. Preliminary results indicate that water table level became more stable after the rewetting in the area affected by the restoration. This seems to have an impact on DOC quantity and quality since concentrations became higher in the same area with also a higher aromaticity degree and a larger proportion of low-weight molecules compared to upstream area. This could indicate that in the downstream area, more anaerobic conditions inhibit microorganism activity responsible for the mineralization of peat organic matter.

Spatial patterns of denitrification and its functional genes in peatlands

NASA Astrophysics Data System (ADS)

Mander, Ülo; Ligi, Teele; Truu, Marika; Truu, Jaak; Pärn, Jaan; Egorov, Sergey; Järveoja, Järvi; Vohla, Christina; Maddison, Martin; Soosaar, Kaido; Oopkaup, Kristjan; Teemusk, Alar; Preem, Jens-Konrad; Uuemaa, Evelyn

2014-05-01

This study is aimed to analyse relationships between the environmental factors and the spatial distribution of the main functional genes nirS, nirK, and nosZ regulating the denitrification process. Variations in hydrological regime, soil temperature and peat quality have been taken into the consideration at both local and global scale. Measurements of greenhouse gas (GHG) emissions using static chambers, groundwater analysis, gas and peat sampling for further laboratory analysis has been conducted in various peatlands in Iceland (two study areas, 2011), Transylvania/Romania (2012), Santa Catarina/Brazil (2012), Quebec/Canada (2012), Bashkortostan/Russian Federation (two study areas, 2012), Sichuan/China (2012), Estonia (two study areas, 2012), Florida/USA (2013, Sologne/France (2013), Jugra in West Siberia/Russia (2013), Uganda (2013), French Guyana (two study areas, 2013), Tasmania (two study areas, 2014) and New Zealand (two study areas, 2014). In each study area at least 2 transects along the groundwater depth gradient, one preferably in undisturbed, another one in drained area, and at least 3 rows of sampling sites (3-5 replicate chambers and 1 piezometer and soil sampling plot in each) in both has been established for studies. In each transect GHG emission was measured during 2-3 days in at least 5 sessions. In addition, organic sediments from the artificial riverine wetlands in Ohio/USA in 2009 and relevant gas emission studies have been used in the analyses. In the laboratories of Estonian University of Life Sciences and the University of Tartu, the peat chemical quality (pH, N, P, C, NH4, NO3) and N2O, CO2, and CH4 concentration in gas samples (50mL glass bottles and exetainers) were analysed. The peat samples for further pyrosequencing and qPCR analyses are stored in fridge by -22oC. This presentation will consider the variation of GHG emissions and hydrological conditions in the study sites. In addition, several selected biophysical factors will be taken into account. Further study will include peatland sites in Montana/USA, Columbia (Andes), Tierra del Fuego/Argentina, Pyrenees/Spain, Savo/Finland, the Netherlands, Okawango/Botswana, Heilongjiang/China, and Kamchatka/Russian Federation. Also, additional analysis will be conducted on the relationships between the intensity of CH4 emissions and methanogenesis regulating functional genes mcrA, pmoA, and dsrAB.

Vegetation associations in a rare community type - Coastal tallgrass prairie

USGS Publications Warehouse

Grace, James B.; Allain, Larry K.; Allen, Charles

2000-01-01

The coastal prairie ecoregion is located along the northwestern coastal plain of the Gulf of Mexico in North America. Because of agricultural and urban development, less than 1% of the original 3.4 million ha of this ecosystem type remains in native condition, making it one of the most endangered ecosystems in North America. The objective of this study was to characterize the vegetation and environmental relationships in a relatively pristine example of lowland coastal prairie in order to provide information for use in conservation and restoration. The study area was a small, isolated prairie located near the southern boundary of the coastal prairie region. Samples were taken along three parallel transects that spanned the prairie. Parameters measured included species composition, elevation, soil characteristics, indications of recent disturbance, above-ground biomass, and light penetration through the plant canopy. Fifty-four species were found in the 107 0.25-m2 plots and a total of 96 species were found at the site. Only two non-native species occurred in sample plots, both of which were uncommon. Cluster analysis was used to identify six vegetation groups, which were primarily dominated by members of the Poaceae or Asteraceae. A conspicuous, natural edaphic feature of the prairie was the presence of 'mima' mounds, which are raised areas approximately 0.5 to 1 m high and 5 to 10 m across. Indicator species analysis revealed a significant number of species that were largely restricted to mounds and these were predominately upland and colonizing species. Ordination was performed using nonmetric, multidimensional scaling. The dominant environmental influence on species composition was found to be elevation and a host of correlated factors including those associated with soil organic content. A secondary group of factors, consisting primarily of soil cations, was found to explain additional variance among plots. Overall, this prairie was found to contain plant associations that are now rare in the surrounding landscape. Within the prairie, plant groups were largely separated by a suite of environmental conditions associated with topography. These results suggest that conservation and restoration efforts will need to carefully consider local topographic influences in order to be successful.

Dual-tracer method to estimate coral reef response to a plume of chemically modified seawater

NASA Astrophysics Data System (ADS)

Maclaren, J. K.; Caldeira, K.

2013-12-01

We present a new method, based on measurement of seawater samples, to estimate the response of a reef ecosystem to a plume of an additive (for example, a nutrient or other chemical). In the natural environment, where there may be natural variability in concentrations, it can be difficult to distinguish between changes in concentrations that would occur naturally and changes in concentrations that result from a chemical addition. Furthermore, in the unconfined natural environment, chemically modified water can mix with waters that have not been modified, making it difficult to distinguish between effects of dilution and effects of chemical fluxes or transformations. We present a dual-tracer method that extracts signals from observations that may be affected by both natural variability and dilution. In this dual-tracer method, a substance (in our example case, alkalinity) is added to the water in known proportion to a passive conservative tracer (in our example case, Rhodamine WT dye). The resulting plume of seawater is allowed to flow over the study site. Two transects are drawn across the plume at the front and back of the study site. If, in our example, alkalinity is plotted as a function of dye concentration for the front transect, the slope of the resulting mixing line is the ratio of alkalinity to dye in the added fluid. If a similar mixing line is measured and calculated for the back transect, the slope of this mixing line will indicate the amount of added alkalinity that remains in the water flowing out of the study site per unit of added dye. The ratio of the front and back slopes indicates the fraction of added alkalinity that was taken up by the reef. The method is demonstrated in an experiment performed on One Tree Reef (Queensland, Australia) aimed at showing that ocean acidification is already affecting coral reef growth. In an effort to chemically reverse some of the changes to seawater chemistry that have occurred over the past 200 years, we added sodium hydroxide to increase alkalinity in the plume and controlled for dilution with Rhodamine WT dye. Preliminary data will be presented and analyzed using the approach described above.

Fruit availability drives the distribution of a folivorous-frugivorous primate within a large forest remnant.

PubMed

Camaratta, Danielle; Chaves, Óscar M; Bicca-Marques, Júlio César

2017-03-01

Understanding the ecological factors that influence the presence, abundance, and distribution of species within their habitats is critical for ensuring their long-term conservation. In the case of primary consumers, such as most primates, the availability and richness of plant foods are considered key drivers of population density at these variables influence the spatial distribution of social units within a finer, habitat patch level scale. We tested the hypothesis that the spatiotemporal availability and richness of plant foods, drive the spatial distribution of brown howler monkeys (Alouatta guariba clamitans) at a fine spatial scale. We established five line transects (2.6-4.3 km long) to census the population of brown howlers in Morro São Pedro, a 1,200 ha Atlantic forest remnant in southern Brazil, every 2 weeks from January to June 2015. We used data from tree inventories performed in sighting and control plots, and phenological surveys of 17 top food tree species to estimate bi-weekly food availability. We recorded a total of 95 sightings. The number of sightings per sampling period ranged from 2 to 12. The availability of fruit (ripe and unripe) was higher in sighting than in control plots, whereas leaf availability and the richness of food tree species was similar. We conclude that the spatial distribution of fruiting trees and the availability of fruit drive the pattern of habitat use, and spacing of brown howler groups in Morro São Pedro. © 2017 Wiley Periodicals, Inc.

Water-quality data for the Ohio River from Willow Island Dam to Belleville Dam, West Virginia and Ohio, May-October 1993

USGS Publications Warehouse

Miller, K.F.

1996-01-01

This report contains water-quality data for the Ohio River from river mile 160.6 (1.1 mile upstream from Willow Island Dam) to river mile 203.6 (0.3 mile upstream from Belleville Dam) that were collected during the summer and fall of 1993. The data were collected to establish the water quality of the Ohio River and to use in assessing the proposed effects of hydropower development on the water quality of the Ohio River. Water quality was monitored by a combination of synoptic field measurements, laboratory analyses, and continuous- record monitoring. Field measurements of water- quality characteristics were made along a longitudinal transect with 24 mid-channel sampling sites; cross-sectional transects of water-quality measurements were made at six of these sites. Water-quality measurements also were made at six sites located on the back-channel (West Virginia) sides of Marietta, Muskingum, and Blennerhassett Islands. At each longitudinal-transect and back- channel sampling site, measurements of specific conductance, pH, water temperature, and dissolved oxygen concentration were made at three depths (about 3.3 feet below the surface of the water, middle of the water column, and near the bottom of the river). Cross-sectional transects consisted of three to four detailed vertical profiles of the same characteristics. Water samples were collected at three depths in the mid-channel vertical profile in each cross-sectional transect and were analyzed for concentrations of phytoplankton chlorophyll a and chlorophyll b. Estimates of the depth of light penetration (Secchi disk transparency) were made at phytoplankton- pigment-sampling locations whenever light and river-surface conditions were appropriate. Each synoptic sampling event was completed in 2 days or less. The entire network was sampled 10 times from May 24 to October 27, 1993. Continuous-record monitoring of water quality consisted of hourly measurments of specific conductance, pH, water temperature, and dissolved oxygen concentration that were made at a depth of 6.6 feet at the ends of the upstream and downstream wingwalls at Willow Island Dam. Continuous-record monitors were operated from May through October 1993.

Evaluation of Scat Deposition Transects versus Radio Telemetry for Developing a Species Distribution Model for a Rare Desert Carnivore, the Kit Fox.

PubMed

Dempsey, Steven J; Gese, Eric M; Kluever, Bryan M; Lonsinger, Robert C; Waits, Lisette P

2015-01-01

Development and evaluation of noninvasive methods for monitoring species distribution and abundance is a growing area of ecological research. While noninvasive methods have the advantage of reduced risk of negative factors associated with capture, comparisons to methods using more traditional invasive sampling is lacking. Historically kit foxes (Vulpes macrotis) occupied the desert and semi-arid regions of southwestern North America. Once the most abundant carnivore in the Great Basin Desert of Utah, the species is now considered rare. In recent decades, attempts have been made to model the environmental variables influencing kit fox distribution. Using noninvasive scat deposition surveys for determination of kit fox presence, we modeled resource selection functions to predict kit fox distribution using three popular techniques (Maxent, fixed-effects, and mixed-effects generalized linear models) and compared these with similar models developed from invasive sampling (telemetry locations from radio-collared foxes). Resource selection functions were developed using a combination of landscape variables including elevation, slope, aspect, vegetation height, and soil type. All models were tested against subsequent scat collections as a method of model validation. We demonstrate the importance of comparing multiple model types for development of resource selection functions used to predict a species distribution, and evaluating the importance of environmental variables on species distribution. All models we examined showed a large effect of elevation on kit fox presence, followed by slope and vegetation height. However, the invasive sampling method (i.e., radio-telemetry) appeared to be better at determining resource selection, and therefore may be more robust in predicting kit fox distribution. In contrast, the distribution maps created from the noninvasive sampling (i.e., scat transects) were significantly different than the invasive method, thus scat transects may be appropriate when used in an occupancy framework to predict species distribution. We concluded that while scat deposition transects may be useful for monitoring kit fox abundance and possibly occupancy, they do not appear to be appropriate for determining resource selection. On our study area, scat transects were biased to roadways, while data collected using radio-telemetry was dictated by movements of the kit foxes themselves. We recommend that future studies applying noninvasive scat sampling should consider a more robust random sampling design across the landscape (e.g., random transects or more complete road coverage) that would then provide a more accurate and unbiased depiction of resource selection useful to predict kit fox distribution.

Probable errors in width distributions of sea ice leads measured along a transect

NASA Technical Reports Server (NTRS)

Key, J.; Peckham, S.

1991-01-01

The degree of error expected in the measurement of widths of sea ice leads along a single transect are examined in a probabilistic sense under assumed orientation and width distributions, where both isotropic and anisotropic lead orientations are examined. Methods are developed for estimating the distribution of 'actual' widths (measured perpendicular to the local lead orientation) knowing the 'apparent' width distribution (measured along the transect), and vice versa. The distribution of errors, defined as the difference between the actual and apparent lead width, can be estimated from the two width distributions, and all moments of this distribution can be determined. The problem is illustrated with Landsat imagery and the procedure is applied to a submarine sonar transect. Results are determined for a range of geometries, and indicate the importance of orientation information if data sampled along a transect are to be used for the description of lead geometries. While the application here is to sea ice leads, the methodology can be applied to measurements of any linear feature.

Comparison of blood chemistry values for samples collected from juvenile chinook salmon by three methods

USGS Publications Warehouse

Congleton, J.L.; LaVoie, W.J.

2001-01-01

Thirteen blood chemistry indices were compared for samples collected by three commonly used methods: caudal transection, heart puncture, and caudal vessel puncture. Apparent biases in blood chemistry values for samples obtained by caudal transection were consistent with dilution with tissue fluids: alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), triglyceride, and K+ were increased and Na+ and Cl- were decreased relative to values for samples obtained by caudal vessel puncture. Some enzyme activities (ALT, AST, LDH) and K+ concentrations were also greater in samples taken by heart puncture than in samples taken by caudal vessel puncture. Of the methods tested, caudal vessel puncture had the least effect on blood chemistry values and should be preferred for blood chemistry studies on juvenile salmonids.

Field trials of line transect methods applied to estimation of desert tortoise abundance

USGS Publications Warehouse

Anderson, David R.; Burnham, Kenneth P.; Lubow, Bruce C.; Thomas, L. E. N.; Corn, Paul Stephen; Medica, Philip A.; Marlow, R.W.

2001-01-01

We examine the degree to which field observers can meet the assumptions underlying line transect sampling to monitor populations of desert tortoises (Gopherus agassizii). We present the results of 2 field trials using artificial tortoise models in 3 size classes. The trials were conducted on 2 occasions on an area south of Las Vegas, Nevada, where the density of the test population was known. In the first trials, conducted largely by experienced biologists who had been involved in tortoise surveys for many years, the density of adult tortoise models was well estimated (-3.9% bias), while the bias was higher (-20%) for subadult tortoise models. The bias for combined data was -12.0%. The bias was largely attributed to the failure to detect all tortoise models on or near the transect centerline. The second trials were conducted with a group of largely inexperienced student volunteers and used somewhat different searching methods, and the results were similar to the first trials. Estimated combined density of subadult and adult tortoise models had a negative bias (-7.3%), again attributable to failure to detect some models on or near the centerline. Experience in desert tortoise biology, either comparing the first and second trials or in the second trial with 2 experienced biologists versus 16 novices, did not have an apparent effect on the quality of the data or the accuracy of the estimates. Observer training, specific to line transect sampling, and field testing are important components of a reliable survey. Line transect sampling represents a viable method for large-scale monitoring of populations of desert tortoise; however, field protocol must be improved to assure the key assumptions are met.

Mollusks of Manuel Antonio National Park, Pacific Costa Rica.

PubMed

Willis, S; Cortés, J

2001-12-01

The mollusks in Manuel Antonio National Park on the central section of the Pacific coast of Costa Rica were studied along thirty-six transects done perpendicular to the shore, and by random sampling of subtidal environments, beaches and mangrove forest. Seventy-four species of mollusks belonging to three classes and 40 families were found: 63 gastropods, 9 bivalves and 2 chitons, during this study in 1995. Of these, 16 species were found only as empty shells (11) or inhabited by hermit crabs (5). Forty-eight species were found at only one locality. Half the species were found at one site, Puerto Escondido. The most diverse habitat was the low rocky intertidal zone. Nodilittorina modesta was present in 34 transects and Nerita scabricosta in 30. Nodilittorina aspera had the highest density of mollusks in the transects. Only four transects did not clustered into the four main groups. The species composition of one cluster of transects is associated with a boulder substrate, while another cluster of transects associates with site. Two clusters were not associated to any of the factors recorded. Some species were present in previous studies but absent in 1995, while others were absent in the previous studies but found in 1995. For example, Siphonaria gigas was present in 1995 in many transects with a relatively high density, but absent in 1962, probably due to human predation before the establishment of the park. Including this study, a total of 97 species of mollusks in three classes and 45 families have been reported from Manuel Antonio National Park. Sixty-nine species are new reports for the area: 53 gastropods, 14 bivalves and 2 chitons. There are probably more species of mollusks at Manuel Antonio National Park, than the 97 reported here, because some areas have not been adequately sampled (e.g., deep environments) and many micro-mollusks could not be identified.

Effects of geoduck (Panopea generosa) aquaculture on resident and transient macrofauna communities of Puget Sound, Washington, USA

USGS Publications Warehouse

Mcdonald, P. Sean; Galloway, Aaron W.E.; McPeek, Kathleen C.; VanBlaricom, Glenn R.

2015-01-01

In Washington state, commercial culture of geoducks (Panopea generosa) involves large-scale out-planting of juveniles to intertidal habitats, and installation of PVC tubes and netting to exclude predators and increase early survival. Structures associated with this nascent aquaculture method are examined to determine whether they affect patterns of use by resident and transient macrofauna. Results are summarized from regular surveys of aquaculture operations and reference beaches in 2009 to 2011 at three sites during three phases of culture: (1) pregear (-geoducks, -structure), (2) gear present (+geoducks, +structures), and (3) postgear (+geoducks, -structures). Resident macroinvertebrates (infauna and epifauna) were sampled monthly (in most cases) using coring methods at low tide during all three phases. Differences in community composition between culture plots and reference areas were examined with permutational analysis of variance and homogeneity of multivariate dispersion tests. Scuba and shoreline transect surveys were used to examine habitat use by transient fish and macroinvertebrates. Analysis of similarity and complementary nonmetric multidimensional scaling were used to compare differences between species functional groups and habitat type during different aquaculture phases. Results suggest that resident and transient macrofauna respond differently to structures associated with geoduck aquaculture. No consistent differences in the community of resident macrofauna were observed at culture plots or reference areas at the three sites during any year. Conversely, total abundance of transient fish and macroinvertebrates were more than two times greater at culture plots than reference areas when aquaculture structures were in place. Community composition differed (analysis of similarity) between culture and reference plots during the gear-present phase, but did not persist to the next farming stage (postgear). Habitat complexity associated with shellfish aquaculture may attract some structure-associated transient species observed infrequently on reference beaches, and may displace other species that typically occur in areas lacking epibenthic structure. This study provides a first look at the effects of multiple phases of geoduck farming on macrofauna, and has important implications for the management of a rapidly expanding sector of the aquaculture industry.

Some comments on Anderson and Pospahala's correction of bias in line transect sampling

USGS Publications Warehouse

Anderson, D.R.; Burnham, K.P.; Chain, B.R.

1980-01-01

ANDERSON and POSPAHALA (1970) investigated the estimation of wildlife population size using the belt or line transect sampling method and devised a correction for bias, thus leading to an estimator with interesting characteristics. This work was given a uniform mathematical framework in BURNHAM and ANDERSON (1976). In this paper we show that the ANDERSON-POSPAHALA estimator is optimal in the sense of being the (unique) best linear unbiased estimator within the class of estimators which are linear combinations of cell frequencies, provided certain assumptions are met.

Top soil radioactivity assessment in a high natural radiation background area: the case of Vinaninkarena, Antsirabe-Madagascar.

PubMed

Rabesiranana, Naivo; Rasolonirina, Martin; Terina, Franck; Solonjara, Asivelo F; Andriambololona, Raoelina

2008-11-01

The village of Vinaninkarena, Antsirabe, Madagascar (47 degrees 02'40''E, 19 degrees 57'17''S) is located in a high natural radioactivity area. In order to evaluate the natural radionuclide content in soil, sampling was done on-site by the transect method (85 soil samples) and off-site through transects across and beyond the region (up to a range of 100 km), to determine the natural radioactivity variation within vs. outside the region, and to detect significant differences, taking into account spatial variability.

Sr-Nd-Hf isotopic fingerprinting of transatlantic dust derived from North Africa

NASA Astrophysics Data System (ADS)

Zhao, Wancang; Balsam, William; Williams, Earle; Long, Xiaoyong; Ji, Junfeng

2018-03-01

Long-range transport of African dust plays an important role in understanding dust-climate relationships including dust source areas, dust pathways and associated atmospheric and/or oceanic processes. Clay-sized Sr-Nd-Hf isotopic compositions can be used as geochemical fingerprints to constrain dust provenance and the pathways of long-range transported mineral dust. We investigated the clay-sized Sr-Nd-Hf isotopic composition of surface samples along four transects bordering the Sahara Desert. The transects are from Mali, Niger/Benin/Togo, Egypt and Morocco. Our results show that the Mali transect on the West African Craton (WAC) produces lower εNd (εNd-mean = -16.38) and εHf (εHf-mean = -9.59) values than the other three transects. The Egyptian transect exhibits the lowest 87Sr/86Sr ratios (87Sr/86Srmean = 0.709842), the highest εHf (εHf-mean = -0.34) and εNd values of the four transects. Comparison of the clay-sized Sr-Nd-Hf isotopic values from our North African samples to transatlantic African dust collected in Barbados demonstrates that the dust's provenance is primarily the western Sahel and Sahara as well as the central Sahel. Summer emission dust is derived mainly from the western Sahel and Sahara regions. The source of transatlantic dust in spring and autumn is more varied than in the summer and includes dust not only from western areas, but also south central areas. Comparison of the Sr-Nd-Hf isotopic fingerprints between the source and sink of transatlantic dust also suggests that a northwestward shift in dust source occurs from the winter, through the spring and into the summer. The isotopic data we develop here provide another tool for discriminating changes in dust archives resulting from paleoenvironmental evolution of source regions.

Effects of continuous cover forestry on soil moisture pattern - Beginning steps of a Hungarian study

NASA Astrophysics Data System (ADS)

Kalicz, Péter; Bartha, Dénes; Brolly, Gábor; Csáfordi, Péter; Csiszár, Ágnes; Eredics, Attila; Gribovszki, Zoltán; Király, Géza; Kollár, Tamás; Korda, Márton; Kucsara, Mihály; Nótári, Krisztina; Kornél Szegedi, Balázs; Tiborcz, Viktor; Zagyvai, Gergely; Zagyvai-Kiss, Katalin Anita

2014-05-01

Nowadays Hungarian foresters encounter a new challenge. The traditional management practices do not meet anymore with the demand of the civil society. The good old clearcut is no more a supported technology in forest regeneration. The transition to the continuous cover forestry induces much higher spatial variability compared to the even aged, more or less homogeneous, monoculture stands. The gap cutting is one of the proposed key methods in the Hungarian forestry. There is an active discussion among forest professionals how to determine the optimal gap size to maintain ideal conditions for the seedlings. Among other open questions for example how the surrounding trees modify the moisture pattern of the forest floor in the gap? In the early steps of a multidisciplinary project we established four research plots to study the spatial and temporal variability of soil moisture in the forest gap and the surrounding undisturbed stand. Each plot is located in oak (Quercus spp.) stands. Natural regeneration of oak stands is more problematic in our climate compared to the beech (Fagus sylvatica) which is located in the more humid or semi-humid areas of our country. All plots are located in the western part of Hungary: close to Sopron, Bejcgyertyános, Vép and Vajszló settlements. The last plot is an extensive research area, which is located in the riparian zone of a tributary of Feketevíz River. We monitor here the close-to-surface groundwater level fluctuation with pressure transducers. With a diurnal fluctuation based method it is possible to quantify the evapotranspiration differences between the gap and the stand. In two of the remaining stands (Bejcgyertyános and Vép) the gaps were opened in 2010. The monitoring of soil moisture began in 2013. A mobile sensor is used to monitor soil-moisture in a regular grid. The spatial variability of soil-moisture time-series shows a characteristic pattern during the growing-season. The plot in Sopron was established in 2013. Gaps with three different sizes were opened and fenced round to close out wild game. The initial status of the gap was recorded by a terrestrial laser scanner (LIDAR). From the resulting 3D point cloud high-resolution digital terrain and canopy surface model are derived which will help the planned numerical modelling. To prevent the unnecessary disturbance in this plot, two perpendicular transects were selected in each gap. The soil-moisture is monitored along these lines together with additional investigations, for example throughfall, and litter interception, tension disc infiltrometry, plant composition and cover. The microclimatic parameters such as near surface air temperature, relative humidity, radiation, wind speed and soil temperature is continuously recorded along the transects and compared to a nearby reference meteorological station located at an open area. Acknowledgment: The research was financially supported by the TÁMOP-4.2.2.A-11/1/KONV-2012-0004 joint EU-national research project

Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms.

PubMed

McGarvey, Richard; Burch, Paul; Matthews, Janet M

2016-01-01

Natural populations of plants and animals spatially cluster because (1) suitable habitat is patchy, and (2) within suitable habitat, individuals aggregate further into clusters of higher density. We compare the precision of random and systematic field sampling survey designs under these two processes of species clustering. Second, we evaluate the performance of 13 estimators for the variance of the sample mean from a systematic survey. Replicated simulated surveys, as counts from 100 transects, allocated either randomly or systematically within the study region, were used to estimate population density in six spatial point populations including habitat patches and Matérn circular clustered aggregations of organisms, together and in combination. The standard one-start aligned systematic survey design, a uniform 10 x 10 grid of transects, was much more precise. Variances of the 10 000 replicated systematic survey mean densities were one-third to one-fifth of those from randomly allocated transects, implying transect sample sizes giving equivalent precision by random survey would need to be three to five times larger. Organisms being restricted to patches of habitat was alone sufficient to yield this precision advantage for the systematic design. But this improved precision for systematic sampling in clustered populations is underestimated by standard variance estimators used to compute confidence intervals. True variance for the survey sample mean was computed from the variance of 10 000 simulated survey mean estimates. Testing 10 published and three newly proposed variance estimators, the two variance estimators (v) that corrected for inter-transect correlation (ν₈ and ν(W)) were the most accurate and also the most precise in clustered populations. These greatly outperformed the two "post-stratification" variance estimators (ν₂ and ν₃) that are now more commonly applied in systematic surveys. Similar variance estimator performance rankings were found with a second differently generated set of spatial point populations, ν₈ and ν(W) again being the best performers in the longer-range autocorrelated populations. However, no systematic variance estimators tested were free from bias. On balance, systematic designs bring more narrow confidence intervals in clustered populations, while random designs permit unbiased estimates of (often wider) confidence interval. The search continues for better estimators of sampling variance for the systematic survey mean.

Characteristics of soils in selected maize growing sites along altitudinal gradients in East African highlands

PubMed Central

Njuguna, Elijah; Gathara, Mary; Nadir, Stanley; Mwalusepo, Sizah; Williamson, David; Mathé, Pierre-Etienne; Kimani, Jackson; Landmann, Tobias; Juma, Gerald; Ong’amo, George; Gatebe, Erastus; Ru, Bruno Le; Calatayud, Paul-andré

2015-01-01

Maize is the main staple crop in the East African Mountains. Understanding how the edaphic characteristics change along altitudinal gradients is important for maximizing maize production in East African Highlands, which are the key maize production areas in the region. This study evaluated and compared the levels of some macro and micro-elements (Al, Ca, Fe, K, Mg, Mn, Na and P) and other soil parameters (pH, organic carbon content, soil texture [i.e. % Sand, % Clay and % Silt], cation exchange capacity [CEC], electric conductivity [EC], and water holding capacity [HC]). Soil samples were taken from maize plots along three altitudinal gradients in East African highlands (namely Machakos Hills, Taita Hills and Mount Kilimanjaro) characterized by graded changes in climatic conditions. For all transects, pH, Ca, K and Mg decreased with the increase in altitude. In contrast, % Silt, organic carbon content, Al and water holding capacity (HC) increased with increasing altitude. The research provides information on the status of the physical–chemical characteristics of soils along three altitudinal ranges of East African Highlands and includes data available for further research. PMID:26509187

Cryptogamic community structure as a bioindicator of soil condition along a pollution gradient.

PubMed

Rola, Kaja; Osyczka, Piotr

2014-09-01

This study aims to determine changes in the structure of cryptogamic vegetation of poor psammophilous grassland along a pollution gradient near a zinc smelter to evaluate the potential of species assemblages as bioindicators of soil condition. Lichens and bryophytes were examined in study plots along six transects in four distance zones, and the physicochemical properties of corresponding soil samples were analysed. Four different responses of species to substrate contamination were identified, with a distinct group of species resistant to and favoured by metal contamination. Although species richness decreases as one approaches the smelter, the gradual replacement of certain sensitive species by resistant ones was observed along the pollution gradient. The results enabled us to develop a useful tool to diagnose strongly polluted sites. Two different cryptogamic assemblages of well-recognised key species characteristic for strongly polluted and lightly polluted sites were distinguished. We conclude that cryptogamic community structure clearly corresponds to the degree of soil contamination, thus demonstrating high bioindicative value. The study confirmed the high relevance of the community approach in metal pollution biomonitoring.

Endosulfan, pentachlorobenzene and short-chain chlorinated paraffins in background soils from Western Europe.

PubMed

Halse, Anne Karine; Schlabach, Martin; Schuster, Jasmin K; Jones, Kevin C; Steinnes, Eiliv; Breivik, Knut

2015-01-01

Soils are major reservoirs for many persistent organic pollutants (POPs). In this study, "newly" regulated POPs i.e. Σendosulfans (α-endosulfan, β-endosulfan, endosulfan sulfate), pentachlorobenzene (PeCB), and short-chain chlorinated paraffins (SCCPs) were determined in background samples from woodland (WL) and grassland (GL) surface soil, collected along an existing latitudinal UK-Norway transect. Statistical analysis, complemented with plots showing the predicted equilibrium distribution and mobility potential, was then explored to discuss factors controlling their spatial distribution. SCCPs were detected with the highest average concentrations (35 ± 100 ng/g soil organic matter (SOM)), followed by Σendosulfans (3 ± 3 ng/g SOM) and PeCB (1 ± 1 ng/g SOM). PeCB and Σendosulfans share many similarities in their distribution in these background soils as well as with several legacy POPs. A steep decline in concentrations of SCCPs with increasing latitude indicates that their occurrence is dictated by proximity to source regions, while concentrations of Σendosulfans peaked in regions experiencing elevated precipitation rates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of even-aged management on forest birds at northern hardwood stand interfaces

Treesearch

Richard M. DeGraaf

1992-01-01

Breeding birds were counted along transects across edges of even-aged northern hardwood stands in the White Mountain National Forest, New Hampshire, U.S.A. Two replicate transects across each of 7 edge types representing 3 classes of contrast (abrupt, intermediate, and subtle) were sampled during June 1983-1985 to define species assemblages at stand edges and estimate...

Elk-effects vegetation monitoring program for Tomales Point Elk Range, Point Reyes National Seashore, California

USGS Publications Warehouse

McEachern, Kathryn; Semenoff-Irving, Marcia; van der Leeden, Pamela

2000-01-01

The monitoring program for elk effects on Tomales Point vegetation is designed to provide information on how tule elk grazing affects plant communities and rare species. The basic objective of the program is to show whether the elk are driving the vegetation into an unacceptable state by their grazing. The expectation is that as elk numbers increase, grazing pressure will increase too, resulting in unacceptable levels of any or all of the following: low vegetation ground cover, poor nutritional quality for the elk, undesirable increases in weedy species, unacceptable loss of native plant biodiversity, population declines in rare plants, population declines in plants used for food and nectar by the endangered silverspot butterfly, and increased erosion.The monitoring program has 3 basic components designed to provide complementary information on different aspects of the elk-vegetation system. Long-term plant community monitoring along permanent transects will show how plant species composition and cover are changing since cattle removal in 1979, and it will show whether any of he undesirable traits listed above are developing in the vegetation. However, monitoring these transects alone will not tell us what the effects of continued grazing by elk are apart from changes the vegetation would be undergoing anyway. In order to tease apart the elk effects from change that is happening because of cattle removal, elk exclosures are needed. By sampling inside and outside exclosures, we will be able to see how elk are modifying the rates and directions of change in the vegetation that would be happening in their absence. In a sense, the exclosures serve as a “check” on elk effects. They will allow us to interpret how much of the change is due to elk and how much can be attributed to other processes such as natural succession or weather patterns. This information will allow us to analyze whether changing elk management will have a desirable effect on the vegetation. Finally, periodic mapping and counting of plants in rare plant populations will show whether plant population ranges are expanding and populations are stable or growing. If not, then management actions can be taken to improve habitat conditions for the plants.A general summary of the rationale and sample design for each of the 3 components of the elk-effects monitoring program follows. Field sampling for the entire program should require about 15 weeks for a 2 to 3- person team, and data processing, analysis, and report writing should require about 9 weeks. Time and labor estimates for this program are given in Table A-1. In addition to elk-effects monitoring, Point Reyes staff periodically monitor fire transects and residual dry matter plots on Tomales Point. They are not included as part of the elk-effects monitoring program and they are described elsewhere. Protocols for fire and residual dry matter sampling are not included in the time estimate for the elk- effects monitoring program.

Avoiding treatment bias of REDD+ monitoring by sampling with partial replacement.

PubMed

Köhl, Michael; Scott, Charles T; Lister, Andrew J; Demon, Inez; Plugge, Daniel

2015-12-01

Implementing REDD+ renders the development of a measurement, reporting and verification (MRV) system necessary to monitor carbon stock changes. MRV systems generally apply a combination of remote sensing techniques and in-situ field assessments. In-situ assessments can be based on 1) permanent plots, which are assessed on all successive occasions, 2) temporary plots, which are assessed only once, and 3) a combination of both. The current study focuses on in-situ assessments and addresses the effect of treatment bias, which is introduced by managing permanent sampling plots differently than the surrounding forests. Temporary plots are not subject to treatment bias, but are associated with large sampling errors and low cost-efficiency. Sampling with partial replacement (SPR) utilizes both permanent and temporary plots. We apply a scenario analysis with different intensities of deforestation and forest degradation to show that SPR combines cost-efficiency with the handling of treatment bias. Without treatment bias permanent plots generally provide lower sampling errors for change estimates than SPR and temporary plots, but do not provide reliable estimates, if treatment bias occurs, SPR allows for change estimates that are comparable to those provided by permanent plots, offers the flexibility to adjust sample sizes in the course of time, and allows to compare data on permanent versus temporary plots for detecting treatment bias. Equivalence of biomass or carbon stock estimates between permanent and temporary plots serves as an indication for the absence of treatment bias while differences suggest that there is evidence for treatment bias. SPR is a flexible tool for estimating emission factors from successive measurements. It does not entirely depend on sample plots that are installed at the first occasion but allows for the adjustment of sample sizes and placement of new plots at any occasion. This ensures that in-situ samples provide representative estimates over time. SPR offers the possibility to increase sampling intensity in areas with high degradation intensities or to establish new plots in areas where permanent plots are lost due to deforestation. SPR is also an ideal approach to mitigate concerns about treatment bias.

Use of the transect method in satellite survey missions with application to the infrared astronomical satellite /IRAS/

NASA Technical Reports Server (NTRS)

Mclaughlin, W. I.; Lundy, S. A.; Ling, H. Y.; Stroberg, M. W.

1980-01-01

The coverage of the celestial sphere or the surface of the earth with a narrow-field instrument onboard a satellite can be described by a set of swaths on the sphere. A transect is a curve on this sphere constructed to sample the coverage. At each point on the transect the number of times that the field-of-view of the instrument has passed over the point is recorded. This information is conveniently displayed as an integer-valued histogram over the length of the transect. The effectiveness of the transect method for a particular observing plan and the best placement of the transects depends upon the structure of the set of observations. Survey missions are usually characterized by a somewhat parallel alignment of the instrument swaths. Using autocorrelation and cross-correlation functions among the histograms the structure of a survey has been analyzed into two components, and each is illustrated by a simple mathematical model. The complex, all-sky survey to be performed by the Infrared Astronomical Satellite (IRAS) is synthesized in some detail utilizing the objectives and constraints of that mission. It is seen that this survey possesses the components predicted by the simple models and this information is useful in characterizing the properties of the IRAS survey and the placement of the transects as a function of celestial latitude and certain structural properties of the coverage.

Vegetation studies on Vandenberg Air Force Base, California

NASA Technical Reports Server (NTRS)

Schmalzer, Paul A.; Hickson, Diana E.; Hinkle, C. Ross

1988-01-01

Vandenburg Air Force Base, located in coastal central California with an area of 98,400 ac, contains resources of considerable biological significance. Available information on the vegetation and flora of Vandenburg is summarized and new data collected in this project are presented. A bibliography of 621 references dealing with vegetation and related topics related to Vanderburg was compiled from computer and manual literature searches and a review of past studies of the base. A preliminary floristic list of 642 taxa representing 311 genera and 80 families was compiled from past studies and plants identified in the vegetation sampling conducted in this project. Fifty-two special interest plant species are known to occur or were suggested to occur. Vegetation was sampled using permanent plots and transects in all major plant communities including chaparral, Bishop pine forest, tanbark oak forest, annual grassland, oak woodland, coastal sage scrub, purple sage scrub, coastal dune scrub, coastal dunes, box elder riparian woodland, will riparian woodland, freshwater marsh, salt marsh, and seasonal wetlands. Comparison of the new vegetation data to the compostie San Diego State University data does not indicate major changes in most communities since the original study. Recommendations are made for additional studies needed to maintain and extend the environmental data base and for management actions to improve resource protection.

The potential impacts of climate change induced changes to tropical leaf albedo and its feedback on global climate

NASA Astrophysics Data System (ADS)

Doughty, C.; Shenkin, A.; Bentley, L. P.; Malhi, Y.

2017-12-01

Tropical forest leaf albedo plays a critical role in global climate by determining how much radiation the planet absorbs near the equator. However, little is known about how tropical leaf albedo could be affected by climate change and how any such changes in albedo could, in turn, impact global climate. Here we measure sunlit leaf albedo along two elevation temperature gradients (a 3000-meter gradient in Peru (10 plots) and a 1500 m gradient in Australia (10 plots) and along two wet to dry transects (a 2000 mm yr-1 gradient in Ghana (10 plots) and a 2000 mm yr-1 gradient in Brazil (10 plots). We found a highly significant increase in visible leaf albedo with wetness at both wet to dry gradients. We also found a marginally significant trend of increased albedo with warmer temperatures along one of the elevation gradients. Leaf albedo can also be impacted by changes in species composition, variations in interspecific variation, and changes in leaf chlorophyll concentrations. We removed the dominant two species from the basal area weighting for each plots but found no significant change, a directional change of interspecific variation could change albedo by 0.01 in the NIR, and changes in chlorophyll could decrease visible albedo by 0.005. We then simulated changes in tropical leaf albedo with a climate model and show that such changes could act as a small negative feedback on climate, but most likely will not have a large impact on future climate.

Adaptation of Rhizome Connections in Drylands: Increasing Tolerance of Clones to Wind Erosion

PubMed Central

Yu, Fei-Hai; Wang, Ning; He, Wei-Ming; Chu, Yu; Dong, Ming

2008-01-01

Background and Aims Wind erosion is a severe stress for plants in drylands, but the mechanisms by which plants withstand erosion remain largely unknown. Here, the hypothesis is tested that maintaining rhizome connections helps plants to tolerate erosion. Methods Five transects were established across an inland dune in Inner Mongolia, China, and measurements were made of leaf number, biomass per ramet and rhizome depth of Psammochloa villosa in 45 plots. In 40 × 40 cm plots of P. villosa on another dune, the top 15 or 30 cm of sand was removed for 1·5 or 3 months to simulate short- and long-term moderate and severe erosion, respectively, with untreated plots as controls, and the rhizomes at the edges of half of the plots were severed to mimic loss of rhizome connections. Key Results Leaf number and biomass per ramet showed quadric relationships with rhizome depth; when rhizomes were exposed to the air, the associated ramets either died or became very weak. Ramet number, leaf number and biomass per plot decreased with increasing erosion severity. Rhizome connections did not affect these traits under control or short-term erosion, but increased them under long-term erosion. Conclusions Rhizome connections alleviated the negative effects of erosion on P. villosa, very likely because the erosion-stressed ramets received water and/or photosynthates translocated from those connected ramets that were not subject to erosion. This study provides the first evidence that maintaining rhizome connections helps plants to tolerate erosion in drylands. PMID:18621966

Distribution of tabanids (Diptera: Tabanidae) along a two-sided altitudinal transect.

PubMed

Hackenberger, Branimir K; Jarić, Davorka; Krcmar, Stjepan

2009-12-01

The pattern of horse fly (Diptera: Tabanidae) distribution and correlations among biodiversity, abundance, abiotic factors, and altitude were determined along a two-sided altitudinal transect. The sampling was carried out on five 3-d periods during tabanid seasonal activity. Linen canopy traps with 1-octen-3-ol as an attractant were used at 20 sampling sites along the transect. The results showed that the qualitative composition of tabanid species can be distinguished by altitude and, especially, between southeastern and northwestern mountain slopes. The peaks of horse fly species richness and abundance were indicated at middle elevations of both slopes, where horse fly distributional groups were overlapping and most rare and infrequent species were sampled. All expected species were sampled according to species accumulation curve. The canonical correlation analysis separated species and sampling sites into three clusters; two were positively correlated with the temperature and the wind but differed in sensitivity toward them, and the third cluster was correlated with the humidity. The horse fly distribution was nonhomogenous, and the distributional patterns were only partially determined by altitude and vegetation. The determining environmental variables were different for each slope: temperature and wind for the southern slope (Mediterranean climatic zone) and humidity for the northern slope (continental climatic zone).

Sedimentation and sediment chemistry, Neopit Mill Pond, Menominee Indian Reservation, Wisconsin, 2001

USGS Publications Warehouse

Fitzpatrick, Faith A.; Peppler, Marie C.

2003-01-01

The volume, texture, and chemistry of sediment deposited in a mill pond on the West Branch of the Wolf River at Neopit, Wis., Menominee Reservation, were studied in 2001-2002. The study was accomplished by examining General Land Office Survey Notes from 1854, establishing 12 transects through the mill pond, conducting soundings of the soft and hard bottom along each transect, and collecting core samples for preliminary screening of potential contaminants. Combined information from transects, cores, and General Land Office Survey notes were used to reconstruct the pre-dam location of the West Branch of the Wolf River through the mill pond. Neopit Mill Pond contains approximately 253 acre-ft of organic-rich muck, on average about 1.2 ft thick, that was deposited after the dam was built. Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with creosote and pentachlorophenol were found in post-dam sediment samples collected from Neopit Mill Pond. Trace-element concentrations were at or near background concentrations. Further study and sampling are needed to identify the spatial extent and variability of the PAHs, pentachlorophenol, and other byproducts from wood preservatives

Using variance components to estimate power in a hierarchically nested sampling design improving monitoring of larval Devils Hole pupfish

USGS Publications Warehouse

Dzul, Maria C.; Dixon, Philip M.; Quist, Michael C.; Dinsomore, Stephen J.; Bower, Michael R.; Wilson, Kevin P.; Gaines, D. Bailey

2013-01-01

We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007–2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of yearly differences in the power of the survey. Results indicated that increasing the sample size at the lowest level of sampling represented the most realistic option to increase the survey's power, fixed plot designs had greater power than random plot designs, and the power of the larval survey varied by year. This study provides an example of how monitoring efforts may benefit from coupling variance components estimation with power analysis to assess sampling design.

[Effects of sampling plot number on tree species distribution prediction under climate change].

PubMed

Liang, Yu; He, Hong-Shi; Wu, Zhi-Wei; Li, Xiao-Na; Luo, Xu

2013-05-01

Based on the neutral landscapes under different degrees of landscape fragmentation, this paper studied the effects of sampling plot number on the prediction of tree species distribution at landscape scale under climate change. The tree species distribution was predicted by the coupled modeling approach which linked an ecosystem process model with a forest landscape model, and three contingent scenarios and one reference scenario of sampling plot numbers were assumed. The differences between the three scenarios and the reference scenario under different degrees of landscape fragmentation were tested. The results indicated that the effects of sampling plot number on the prediction of tree species distribution depended on the tree species life history attributes. For the generalist species, the prediction of their distribution at landscape scale needed more plots. Except for the extreme specialist, landscape fragmentation degree also affected the effects of sampling plot number on the prediction. With the increase of simulation period, the effects of sampling plot number on the prediction of tree species distribution at landscape scale could be changed. For generalist species, more plots are needed for the long-term simulation.

End-point diameter and total length coarse woody debris models for the United States

Treesearch

C.W. Woodall; J.A. Westfall; D.C. Lutes; S.N. Oswalt

2008-01-01

Coarse woody debris (CWD) may be defined as dead and down trees of a certain minimumsize that are an important forest ecosystem component (e.g., wildlife habitat, carbon stocks, and fuels). Due to field efficiency concerns, some natural resource inventories only measure the attributes of CWD pieces at their point of intersection with a sampling transect (e.g., transect...

The distribution of mercury in a forest floor transect across the central United States

Treesearch

Charles H. (Hobie) Perry; Michael C. Amacher; William Cannon; Randall K. Kolka; Laurel Woodruff

2009-01-01

Mercury (Hg) stored in soil organic matter may be released when the forest floor is consumed by fire. Our objective is to document the spatial distribution of forest floor Hg for a transect crossing the central United States. Samples collected by the Forest Service, U.S. Department of Agriculture's Forest Inventory and Analysis Soil Quality Indicator were tested...

Field Testing New Plot Designs and Methods for Determining Hydrophytic Vegetation during Wetland Delineations in the United States

DTIC Science & Technology

2014-03-01

Trees and woody vines are sampled in large plots with 9 m (30 ft) radii. Saplings, shrubs , and herbs are sampled in nested smaller plots with 2 m (5 ft... woody vines in 9 m (30 ft) radius plots and saplings, shrubs , and herbaceous species in 2 m (5 ft) radius plots. In herbaceous meadows, only the 2 m (5...suggests stratifying vegetation by growth forms of trees, shrubs , herbs, and vines and sampling plant communities by using nested circular plots

A field experiment and numerical modeling of a tracer at a gravel beach in Prince William Sound, Alaska

NASA Astrophysics Data System (ADS)

Guo, Qiaona; Li, Hailong; Boufadel, Michel C.; Liu, Jin

2014-12-01

Oil from the 1989 Exxon Valdez oil spill persists in many gravel beaches in Prince William Sound (Alaska, USA), despite great remedial efforts. A tracer study using lithium at a gravel beach on Knight Island, Prince William Sound, during the summer of 2008 is reported. The tracer injection and transport along a transect were simulated using the two-dimensional numerical model MARUN. Model results successfully reproduced the tracer concentrations observed at wells along the transect. A sensitivity analysis revealed that the estimated parameters are well determined. The simulated spatial distribution of tracer indicated that nutrients applied along the transect for bioremediation purposes would be washed to the sea very quickly (within a semi-diurnal tidal cycle) by virtue of the combination of the two-layered beach structure, the tidal fluctuation and the freshwater flow from inland. Thus, pore-water samples in the transect were found to be clean due to factors other than bioremediation. This may explain why the oil did not persist within the transect.

Niche modelling of marsh plants based on occurrence and abundance data.

PubMed

Lou, Yanjing; Gao, Chuanyu; Pan, Yanwen; Xue, Zhenshan; Liu, Ying; Tang, Zhanhui; Jiang, Ming; Lu, Xianguo; Rydin, Håkan

2018-03-01

The information of species' response (optimum or critical limits along environmental gradients) is a key to understanding ecological questions and to design management plans. A large number of plots (762) from 70 transects of 13 wetland sites in Northeast China were sampled along flooding gradient from marsh to wet meadow. Species response (abundance and occurrence) to flooding were modelled with Generalized Additive Models for 21 dominant plant species. We found that 20 of 21 species showed a significant response to flooding for the occurrence and abundance models, and four types of response were found: monotonically increasing, monotonically decreasing, skewed unimodal and symmetric unimodal. The species with monotonically increasing response have the deepest flooding optimum and widest niche width, followed by those with unimodal curve, and the monotonically decreasing ones have the smallest values. The optima and niche width (whether based on occurrence or abundance models) both significantly correlated with the frequency, but not with mean abundance. Abundance models outperformed occurrence models based on goodness of fit. The abundance models predicted a rather sharp shift from dominance of helophytes (Carex pseudo-curaica and C. lasiocarpa) to wet meadow species (Calamagrostis angustifolia and Carex appendiculata) if water levels drop from about 10cm above soil surface to below the surface. The defined optima and niche width based on the abundance models can be applied to better instruct restoration management. Given the time required to collect abundance data, an efficient strategy could be to monitor occurrence in many plots and abundance in a subset of these. Copyright © 2017 Elsevier B.V. All rights reserved.

Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats.

PubMed

Braun de Torrez, Elizabeth C; Wallrichs, Megan A; Ober, Holly K; McCleery, Robert A

2017-01-01

Due to increasing threats facing bats, long-term monitoring protocols are needed to inform conservation strategies. Effective monitoring should be easily repeatable while capturing spatio-temporal variation. Mobile acoustic driving transect surveys ('mobile transects') have been touted as a robust, cost-effective method to monitor bats; however, it is not clear how well mobile transects represent dynamic bat communities, especially when used as the sole survey approach. To assist biologists who must select a single survey method due to resource limitations, we assessed the effectiveness of three acoustic survey methods at detecting species richness in a vast protected area (Everglades National Park): (1) mobile transects, (2) stationary surveys that were strategically located by sources of open water and (3) stationary surveys that were replicated spatially across the landscape. We found that mobile transects underrepresented bat species richness compared to stationary surveys across all major vegetation communities and in two distinct seasons (dry/cool and wet/warm). Most critically, mobile transects failed to detect three rare bat species, one of which is federally endangered. Spatially replicated stationary surveys did not estimate higher species richness than strategically located stationary surveys, but increased the rate at which species were detected in one vegetation community. The survey strategy that detected maximum species richness and the highest mean nightly species richness with minimal effort was a strategically located stationary detector in each of two major vegetation communities during the wet/warm season.

Comparison of Relative Bias, Precision, and Efficiency of Sampling Methods for Natural Enemies of Soybean Aphid (Hemiptera: Aphididae).

PubMed

Bannerman, J A; Costamagna, A C; McCornack, B P; Ragsdale, D W

2015-06-01

Generalist natural enemies play an important role in controlling soybean aphid, Aphis glycines (Hemiptera: Aphididae), in North America. Several sampling methods are used to monitor natural enemy populations in soybean, but there has been little work investigating their relative bias, precision, and efficiency. We compare five sampling methods: quadrats, whole-plant counts, sweep-netting, walking transects, and yellow sticky cards to determine the most practical methods for sampling the three most prominent species, which included Harmonia axyridis (Pallas), Coccinella septempunctata L. (Coleoptera: Coccinellidae), and Orius insidiosus (Say) (Hemiptera: Anthocoridae). We show an important time by sampling method interaction indicated by diverging community similarities within and between sampling methods as the growing season progressed. Similarly, correlations between sampling methods for the three most abundant species over multiple time periods indicated differences in relative bias between sampling methods and suggests that bias is not consistent throughout the growing season, particularly for sticky cards and whole-plant samples. Furthermore, we show that sticky cards produce strongly biased capture rates relative to the other four sampling methods. Precision and efficiency differed between sampling methods and sticky cards produced the most precise (but highly biased) results for adult natural enemies, while walking transects and whole-plant counts were the most efficient methods for detecting coccinellids and O. insidiosus, respectively. Based on bias, precision, and efficiency considerations, the most practical sampling methods for monitoring in soybean include walking transects for coccinellid detection and whole-plant counts for detection of small predators like O. insidiosus. Sweep-netting and quadrat samples are also useful for some applications, when efficiency is not paramount. © 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.

Namib Desert Soil Microbial Community Diversity, Assembly, and Function Along a Natural Xeric Gradient.

PubMed

Scola, Vincent; Ramond, Jean-Baptiste; Frossard, Aline; Zablocki, Olivier; Adriaenssens, Evelien M; Johnson, Riegardt M; Seely, Mary; Cowan, Don A

2018-01-01

The hyperarid Namib desert is a coastal desert in southwestern Africa and one of the oldest and driest deserts on the planet. It is characterized by a west/east increasing precipitation gradient and by regular coastal fog events (extending up to 75 km inland) that can also provide soil moisture. In this study, we evaluated the role of this natural aridity and xeric gradient on edaphic microbial community structure and function in the Namib desert. A total of 80 individual soil samples were collected at 10-km intervals along a 190-km transect from the fog-dominated western coastal region to the eastern desert boundary. Seventeen physicochemical parameters were measured for each soil sample. Soil parameters reflected the three a priori defined climatic/xeric zones along the transect ("fog," "low rain," and "high rain"). Microbial community structures were characterized by terminal restriction fragment length polymorphism fingerprinting and shotgun metaviromics, and their functional capacities were determined by extracellular enzyme activity assays. Both microbial community structures and activities differed significantly between the three xeric zones. The deep sequencing of surface soil metavirome libraries also showed shifts in viral composition along the xeric transect. While bacterial community assembly was influenced by soil chemistry and stochasticity along the transect, variations in community "function" were apparently tuned by xeric stress.

Sampling Error in Relation to Cyst Nematode Population Density Estimation in Small Field Plots.

PubMed

Župunski, Vesna; Jevtić, Radivoje; Jokić, Vesna Spasić; Župunski, Ljubica; Lalošević, Mirjana; Ćirić, Mihajlo; Ćurčić, Živko

2017-06-01

Cyst nematodes are serious plant-parasitic pests which could cause severe yield losses and extensive damage. Since there is still very little information about error of population density estimation in small field plots, this study contributes to the broad issue of population density assessment. It was shown that there was no significant difference between cyst counts of five or seven bulk samples taken per each 1-m 2 plot, if average cyst count per examined plot exceeds 75 cysts per 100 g of soil. Goodness of fit of data to probability distribution tested with χ 2 test confirmed a negative binomial distribution of cyst counts for 21 out of 23 plots. The recommended measure of sampling precision of 17% expressed through coefficient of variation ( cv ) was achieved if the plots of 1 m 2 contaminated with more than 90 cysts per 100 g of soil were sampled with 10-core bulk samples taken in five repetitions. If plots were contaminated with less than 75 cysts per 100 g of soil, 10-core bulk samples taken in seven repetitions gave cv higher than 23%. This study indicates that more attention should be paid on estimation of sampling error in experimental field plots to ensure more reliable estimation of population density of cyst nematodes.

Considerations in Forest Growth Estimation Between Two Measurements of Mapped Forest Inventory Plots

Treesearch

Michael T. Thompson

2006-01-01

Several aspects of the enhanced Forest Inventory and Analysis (FIA) program?s national plot design complicate change estimation. The design incorporates up to three separate plot sizes (microplot, subplot, and macroplot) to sample trees of different sizes. Because multiple plot sizes are involved, change estimators designed for polyareal plot sampling, such as those...

Pb-concentrations and Pb-isotope ratios in soils collected along an east-west transect across the United States

USGS Publications Warehouse

Reimann, Clemens; Smith, David B.; Woodruff, Laurel G.; Flem, Belinda

2011-01-01

Analytical results for Pb-concentrations and isotopic ratios from ca. 150 samples of soil A horizon and ca. 145 samples of soil C horizon collected along a 4000-km east–west transect across the USA are presented. Lead concentrations along the transect show: (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for central to eastern USA (Missouri to Maryland) when compared to the western USA (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern USA (1.35 vs. 1.14). Lead isotopes show a distinct trend across the USA, with the highest 206Pb/207Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g., California, median A-horizon: 1.195; C-horizon: 1.216). The soil C-horizon samples show generally higher 206Pb/207Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The 206Pb/207Pb-isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb-concentration and 206Pb/207Pb-isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes.

COMPARISON OF USEPA FIELD SAMPLING METHODS FOR BENTHIC MACROINVERTEBRATE STUDIES

EPA Science Inventory

Two U.S. Environmental Protection Agency (USEPA) macroinvertebrate sampling protocols were compared in the Mid-Atlantic Highlands region. The Environmental Monitoring and Assessment Program (EMAP) wadeable streams protocol results in a single composite sample from nine transects...

Distribution, Sources, and Association of Polycyclic Aromatic Hydrocarbons, Black Carbon, and Total Organic Carbon in Size-Segregated Soil Samples Along a Background–Urban–Rural Transect

PubMed Central

Ray, Sharmila; Khillare, Pandit Sudan; Kim, Ki-Hyun; Brown, Richard J.C.

2012-01-01

Abstract Soil samples were collected over a year-long period along a background–urban–rural transect in Delhi, India for the analysis of polycyclic aromatic hydrocarbons (PAHs), black carbon (BC), and total organic carbon (TOC) in five grain size fractions, x, in μm of 0≤x<53 (I), 53≤x<250 (II), 250≤x<500 (III), 500≤x<2000 (IV), and their sum (total: T). Maximum concentrations of PAH, BC, and TOC were observed in the smallest fraction (I) comprising silt and clay, irrespective of site or season. Results of the molecular diagnostic ratios and principal component analysis (PCA) identified coal, wood, biomass burning, and vehicular emissions as major sources of PAHs at all the three sites, while BC/TOC ratios pointed toward biomass combustion as the chief source of carbonaceous species. This work presents the first such rural-urban transect study considering PAH, BC, and TOC in soil. PMID:23133309

Visualization tools for model/data comparisons and decision making during the Monterey Bay 2006 experiment.

NASA Astrophysics Data System (ADS)

Pawlowski, L.; Kolber, D.; Godin, M.; Chavez, F. P.

2006-12-01

During summer 2006, almost 100 different oceanographic sensors have captured for more than one month the properties of the waters of the Californian Central Coast. Data were assimilated in quasi-real time by three hydrodynamical models to forecast the evolution of the local conditions such as currents, sea water temperature, salinity and to adapt accordingly the sampling strategy of the involved unmanned vehicles (AUV, gliders). Due to the high diversity of data and models (sources, file structures, time and spatial coverage, periodicity of sampling), the collected informations were first converted into a standardized format which allows one to quickly find and extract the relevant variables from the main data server of the experiment. Visualization softwares were developed to provide live maps of the latest locations of instruments, surface plots and vertical transects of currents, temperature and salinity from data and models. These products were mainly used for decision making, for model intercomparison and to evaluate the quality of the data assimilation process for each model. Plots were updated several times a day and automatically posted on an internet collaborative portal. Softwares were adaptive in regards of the availability of simulations and datasets from satellite, aircraft, robotic vehicles, research vessels, moorings, drifters Their modular structures allowed a quick implementation of new instruments during the experiment. Profiles from gliders and AUV served as references for intercomparisons between models for salinity and temperature. As simulations were not synchronized between models, the involved algorithm selected, for all gliders, relevant portions of their tracks to serve as references for model intercomparison. These portions were delimited to prioritize the comparison for each model between observations and nowcasts/hindcasts and also to evaluate the loss of forecasting capabilities with time. We provide here several examples of these graphical products for different situations we encountered during the experiment.

Quantifying uncertainty in carbon and nutrient pools of coarse woody debris

NASA Astrophysics Data System (ADS)

See, C. R.; Campbell, J. L.; Fraver, S.; Domke, G. M.; Harmon, M. E.; Knoepp, J. D.; Woodall, C. W.

2016-12-01

Woody detritus constitutes a major pool of both carbon and nutrients in forested ecosystems. Estimating coarse wood stocks relies on many assumptions, even when full surveys are conducted. Researchers rarely report error in coarse wood pool estimates, despite the importance to ecosystem budgets and modelling efforts. To date, no study has attempted a comprehensive assessment of error rates and uncertainty inherent in the estimation of this pool. Here, we use Monte Carlo analysis to propagate the error associated with the major sources of uncertainty present in the calculation of coarse wood carbon and nutrient (i.e., N, P, K, Ca, Mg, Na) pools. We also evaluate individual sources of error to identify the importance of each source of uncertainty in our estimates. We quantify sampling error by comparing the three most common field methods used to survey coarse wood (two transect methods and a whole-plot survey). We quantify the measurement error associated with length and diameter measurement, and technician error in species identification and decay class using plots surveyed by multiple technicians. We use previously published values of model error for the four most common methods of volume estimation: Smalian's, conical frustum, conic paraboloid, and average-of-ends. We also use previously published values for error in the collapse ratio (cross-sectional height/width) of decayed logs that serves as a surrogate for the volume remaining. We consider sampling error in chemical concentration and density for all decay classes, using distributions from both published and unpublished studies. Analytical uncertainty is calculated using standard reference plant material from the National Institute of Standards. Our results suggest that technician error in decay classification can have a large effect on uncertainty, since many of the error distributions included in the calculation (e.g. density, chemical concentration, volume-model selection, collapse ratio) are decay-class specific.

Factors controlling floc settling velocity along a longitudinal estuarine transect

USGS Publications Warehouse

Manning, A.J.; Schoellhamer, D.H.

2013-01-01

A 147 km longitudinal transect of flocculated cohesive sediment properties in San Francisco Bay (SFB) was conducted on June 17th, 2008. Our aim was to determine the factors that control floc settling velocity along the longitudinal axis of the estuary. The INSSEV-LF video system was used to measure floc diameters and settling velocities at 30 stations at a distance of 0.7 m above the estuary bed. Floc sizes (D) ranged from 22 μm to 639 μm and settling velocities (Ws) ranged between 0.04 mm·s− 1 and 15.8 mm·s− 1 during the longitudinal transect. Nearbed turbulent shear stresses throughout the transect duration were within the 0.2–0.5 Pa range which typically stimulates flocculation growth. The individual D–Ws–floc density plots suggest the suspended sediments encountered throughout SFB were composed of both muddy cohesive sediment and mixed sediments flocs. Mass-weighted population mean settling velocity (Wsmass) ranged from 0.5 mm·s− 1 to 10 mm·s− 1. The macrofloc and microfloc (demarcation at 160 μm) sub-populations demonstrated parameterised settling velocities which spanned nearly double the range of the sample mean settling velocities (Wsmean). The macroflocs tended to dominate the suspended mass (up to 77% of the ambient suspended solid concentration; SSC) from San Pablo Bay to Carquinez Strait (the vicinity of the turbidity maximum zone). Microfloc mass was particularly significant (typically 60–100% of the SSC) in the northern section of South Bay and most of Central Bay. The transect took eleven hours to complete and was not fully synoptic. During slack tide, larger and faster settling flocs deposited, accounting for most of the longitudinal variability. The best single predictor of settling velocity was water velocity 39 min prior to sampling, not suspended-sediment concentration or salinity. Resuspension and settling lags are likely responsible for the lagged response of settling velocity to water velocity. The distribution of individual floc diameters and settling velocities indicates that floc density for a given floc diameter varies greatly. A small portion (a few percent) of suspended sediment mass in SFB is sand-sized and inclusion of sand in flocs appears likely. Fractal theory for cohesive sediment assumes that there is a single primary particle size that flocculates, which is not the case for these types of mixed sediment flocs. The wide variability in the physical, biological and chemical processes which contribute to flocculation within SFB means that spatial floc data is required in order to accurately represent the diverse floc dynamics present in the Bay system. The importance in determining accurate estimates of floc density has been highlighted by the SFB data, as these provide the basis for realistic distributions of floc dry mass and the mass settling flux across a floc population. However, although video floc sampling devices can produce the various floc property trends observed in SFB, good survey practice is still paramount. One can see that if the sampling coverage (i.e. data collection frequency) is poor, this could lead to potential mis-interpretations of the data and only limited conclusions may be drawn from such a restricted survey. For example, a limited survey (i.e. only 3 stations, compared to the 10 stations in the full survey) in South Bay produces an under-estimate in both the macrofloc SSCmacro distribution by a factor of four and the Wsmacro by a factor of two. To develop sediment transport numerical models for SFB, high quality floc size and settling data are needed to understand and simulate the depositional qualities of both suspended cohesive sediment and mixed sediments in San Francisco Bay. This study has shown that the most pragmatic solution is a physically-based approach, whereby the detailed flocs D vs. Ws spectra are parameterised in terms of their macrofloc and microfloc properties. This aids in model calibration, whilst retaining more of the dynamical aspects of the floc populations. All forms of flocculation are dynamically active processes, therefore it is important to also include both SSC and turbulence functions together with the floc data.

Recording Fathometer Techniques for Determining Distribution and Biomass of Hydrilla verticillata Royle.

DTIC Science & Technology

1980-10-01

infestation or extent of open water was measured following the same procedures described for deter- fmination of transect percent cover. This value was...procedure where the last vegetation type ended along the transect (i.e. hydrilla, eelgrass, open water ), vegetation coverage was determined for the entire...ated open water , no measurements were made. Approximately 150 to 200 prediction stations were used per monthly sample. 61. For sparse and thick

Adaptive kernel function using line transect sampling

NASA Astrophysics Data System (ADS)

Albadareen, Baker; Ismail, Noriszura

2018-04-01

The estimation of f(0) is crucial in the line transect method which is used for estimating population abundance in wildlife survey's. The classical kernel estimator of f(0) has a high negative bias. Our study proposes an adaptation in the kernel function which is shown to be more efficient than the usual kernel estimator. A simulation study is adopted to compare the performance of the proposed estimators with the classical kernel estimators.

Influence of skid trails and haul roads on understory plant richness and composition in managed forest landscapes in Upper Michigan, USA

Treesearch

David S. Buckley; Thomas R. Crow; Elizabeth A. Nauertz; Kurt E. Schulz

2003-01-01

We evaluated impacts of disturbance in interior haul roads and skid trails on understory vegetation by documenting the areal extent of these features and plant composition along 10 m x 100 m belt transects. Ten belt transects were sampled in each of three comparable northern hardwood forests under even-aged management. These forests were approximately 80 years old and...

Estimating the encounter rate variance in distance sampling

USGS Publications Warehouse

Fewster, R.M.; Buckland, S.T.; Burnham, K.P.; Borchers, D.L.; Jupp, P.E.; Laake, J.L.; Thomas, L.

2009-01-01

The dominant source of variance in line transect sampling is usually the encounter rate variance. Systematic survey designs are often used to reduce the true variability among different realizations of the design, but estimating the variance is difficult and estimators typically approximate the variance by treating the design as a simple random sample of lines. We explore the properties of different encounter rate variance estimators under random and systematic designs. We show that a design-based variance estimator improves upon the model-based estimator of Buckland et al. (2001, Introduction to Distance Sampling. Oxford: Oxford University Press, p. 79) when transects are positioned at random. However, if populations exhibit strong spatial trends, both estimators can have substantial positive bias under systematic designs. We show that poststratification is effective in reducing this bias. ?? 2008, The International Biometric Society.

Mesoscale variability observed in the Northern Adriatic in autumn 2016

NASA Astrophysics Data System (ADS)

Pasaric, Zoran; Iva, Medjugorac; Nastjenka, Supic; Tamara, Djakovac; Mirko, Orlic

2017-04-01

Quasi-synoptic measurements of hydrographic properties were performed in the Northern Adriatic along the transect extending from Rovinj to the Po River mouth in an approximately east-west direction. The depth along the transect slowly varies between 30 and 40 m. Three one-day cruises were conducted, the first on 12 Nov, the second on 18 Nov, and the third on 25 Nov 2016. During the first and the third cruise the sampling was done with a CTD probe lowered from the surface to the bottom, at eleven stations placed nearly equidistantly along the transect. Average distance between the stations was 6 km. The second cruise was conducted with a towed yo-yo profiler equipped with the CTD probe and continuously undulating between the surface and some 4 m above the bottom. With roughly three undulations per kilometer, horizontal resolution along the transect was about 200 m. The data suggest that three processes occurred during the cruises: 1) surface cooling and related vertical mixing, 2) intrusion of high-salinity waters into the western part of the transect, and 3) propagation of a mesoscale formation in a westward direction. The existence and propagation of the mesoscale feature is supported by a simple analytical model of topographic Rossby waves. By assuming that the bottom varies linearly in the direction perpendicular to the transect, the propagation speed of O(1 km/day) is obtained - in agreement with the observations.

Distribution of clay minerals on the Alaskan margin near Barrow Canyon revealed by Diffuse Spectral Reflectance measurements

NASA Astrophysics Data System (ADS)

Orsburn, C.; Ortiz, J. D.; Polyak, L.; Grebmeier, J. M.; Darby, D.

2007-12-01

Sediment clay mineral assemblages provide an excellent means of assessing the provenance of Arctic sediment due to the variety of sediment transport mechanisms at work and the existence of distinct weathering sources from differing bedrock geology. During HOTRAX Leg 1 aboard the USCG Ice breaker Healy (cruise HLY0501), we collected jumbo piston cores on the Alaskan margin near Barrow Canyon which provide detailed Holocene sedimentary records. Measurements of Diffuse Spectral Reflectance (DSR) were collected at 1cm resolution from the split surface of the cores using a Minolta CM-2600d UV/VIS spectrophotometer (400-700nm wavelength range; 10nm resolution; 3mm spot size). To interpret the resulting downcore records, we present a preliminary study using 28 coretop sediment samples collected by the Shelf-Basin Interaction program in 2004 arrayed in four transects across the shelf near Barrow Canyon. The samples were analyzed using an ASD Labspec Pro FR UV/VIS/NIR spectrometer (250-2500nm wavelength range, 2-10nm resolution; 20mm spot size). Our results indicate that the measurements from the two instruments are offset by constant factors, but can be easily compared. To estimate the clay mineralogy of the cores, we decomposed the matrix of DSR measurements from the coretop and downcore samples using principle component analysis and compared the resulting factor score patterns with mineral diffuse spectral reflectance signatures from known samples measured in our lab or available from version 5 of the USGS Digital Spectral Library. The three leading modes extracted by principle component analysis of the downcore samples are applicable to the coretops. We infer that the first principle component mode relates to smectite, the second to chlorite, and the third to a mixture of illite and goethite (herein referred to as illite - goethite). The geographic and bathymetric trends in the coretop data indicate that (1) the smectite and illite - goethite components both increase with depth and reach greater values in the two western transects than in the two eastern transects closest to the coast and Barrow Canyon, (2) the smectite and illite- goethite components are anticorrelated in the two western transects, but not in the two eastern transects, (3) chlorite decreases with depth and is highest in the two transects closest to Barrow Canyon. These results suggest that the chlorite on the Alaskan margin is transported by nearshore currents from the Bering Straight and then by bottom currents flowing through the Barrow Canyon. Accordingly, we interpret downcore chlorite peaks inferred from DSR measurements in our sediment cores as evidence of times of enhanced input of Pacific water to the Alaskan Margin.

Postoperative occipital neuralgia with and without C2 nerve root transection during atlantoaxial screw fixation: a post-hoc comparative outcome study of prospectively collected data.

PubMed

Yeom, Jin S; Buchowski, Jacob M; Kim, Ho-Joong; Chang, Bong-Soon; Lee, Choon-Ki; Riew, K Daniel

2013-07-01

Although routine transection of the C2 nerve root during atlantoaxial segmental screw fixation has been recommended by some surgeons, it remains controversial and to our knowledge no comparative studies have been performed to determine whether transection or preservation of the C2 nerve root affects patient-derived sensory outcomes. The purpose of this study is to specifically analyze patient-derived sensory outcomes over time in patients with intentional C2 nerve root transection during atlantoaxial segmental screw fixation compared with those without transection. This is a post-hoc comparative analysis of prospectively collected patient-derived outcome data. The sample consists of 24 consecutive patients who underwent intentional bilateral transection of the C2 nerve root during posterior atlantoaxial segmental screw fixation (transection group) and subsequent 41 consecutive patients without transection (preservation group). A visual analog scale (VAS) score was used for occipital neuralgia as the primary outcome measure and VAS score for neck pain, neck disability index score and Japanese Orthopedic Association score for cervical myelopathy and recovery rate, with bone union rate as the secondary outcome measure. Patient-derived outcomes including change in VAS score for occipital neuralgia over time were statistically compared between the two groups. This study was not supported by any financial sources and there is no topic-specific conflict of interest related to the authors of this study. Seven (29%) of the 24 patients in the transection group experienced increased neuralgic pain at 1 month after surgery either because of newly developed occipital neuralgia or aggravation of preexisting occipital neuralgia. Four of the seven patients required almost daily medication even at the final follow-up (44 and 80 months). On the other hand, only four (10%) of 41 patients in the preservation group had increased neuralgic pain at 1 month after surgery, and at ≥ 1 year, no patients had increased neuralgic pain. The difference in the prevalence of increased neuralgic pain between the two groups was statistically significant at all time points (3, 6, 12, and 24 months postoperatively) except at 1 month postoperatively. The intensity of neuralgic pain, which preoperatively had not been significantly different between the two groups, was significantly higher in the transection group at the final follow-up. C2 nerve root transection is not a benign procedure and, in our experience, more than a quarter of the patients experience increased neuralgic pain following C2 nerve root transection. Because the prevalence and intensity of postoperative neuralgia was significantly higher with C2 nerve root transection than with its preservation, we recommend against routine C2 nerve root transection when performing atlantoaxial segmental screw fixation. Copyright © 2013 Elsevier Inc. All rights reserved.

Chondroprotective effects of zoledronic acid on articular cartilage in dogs with experimentally induced osteoarthritis.

PubMed

Dearmin, Michael G; Trumble, Troy N; García, Anapatricia; Chambers, Jon N; Budsberg, Steven C

2014-04-01

To assess effects of zoledronic acid on biomarkers, radiographic scores, and gross articular cartilage changes in dogs with induced osteoarthritis. 21 purpose-bred hound-type dogs. The left stifle joint of each dog was examined arthroscopically to determine initial articular cartilage status, which was followed by cranial cruciate ligament (CrCL) transection to induce osteoarthritis. Dogs were assigned to 3 groups (control group, low dose [10 μg of zoledronic acid/kg], or high dose [25 μg of zoledronic acid/kg). Treatments were administered SC every 3 months for 1 year beginning the day after CrCL transection. Serum and synovial fluid samples and radiographs were obtained 0, 1, 3, 6, 9, and 12 months after transection. At 12 months, each joint was scored for cartilage defects. Serum and synovial fluid biomarkers of bone and cartilage turnover (bone-specific alkaline phosphatase, type I and II collagen, carboxy-propeptide of type II collagen, and chondroitin sulfate 846) were analyzed with ELISAs. The high-dose group had fewer total articular defects and lower severity scores in CrCL-transected stifle joints than did the control group. In addition, the high-dose group had significantly less change in collagenase cleavage of type I or II collagen in the synovial fluid at 1 and 3 months after CrCL transection than did the control group and also had greater changes in bone-specific alkaline phosphatase in synovial fluid at 3 months after CrCL transection than did the control group. Zoledronic acid had a chondroprotective effect in dogs with a transected CrCL.

Total Storage and Landscape Partitioning of Soil Organic Carbon and Phytomass Carbon in Siberia

NASA Astrophysics Data System (ADS)

Siewert, M. B.; Hanisch, J.; Weiss, N.; Kuhry, P.; Hugelius, G.

2014-12-01

We present results of detailed partitioning of soil organic carbon (SOC) and phytomass carbon (PC) from two study sites in Siberia. The study sites in the Tundra (Kytalyk) and the Taiga (Spasskaya Pad) reflect two contrasting environments in the continuous permafrost zone. In total 57 individual field sites (24 and 33 per study site respectively) have have been sampled for SOC and PC along transects cutting across different land covers. In Kytalyk the sampling depth for the soil pedons was 1 m depth. In Spasskaya Pad where the active layer was significantly deeper, we aimed for 2 m depth or tried to include at least the top of the permafrost. Here the average depth of soil profiles was 152 cm. PC was sampled from 1x1 m ground coverage plots. In Spasskaya Pad tree phytomass was also estimated on a 5x5 m plot. The SOC storage was calculated separately for the intervals 0-30 cm, 30-100 cm and 100-200 cm (the latter only for Spasskaya Pad), as well as for organic layer vs. mineral soil, active layer vs. permafrost and for cryoturbated soil horizons. Landscape partitioning was performed by thematic up-scaling using a vegetation based land cover classification of very high resolution (2x2 m) satellite imagery. Non-Metric Multidimensional Scaling (NMDS) was used to explore the relationship of SOC with PC and different soil and permafrost related variables. The results show that the different land cover classes can be considered distinct storages of SOC, but that PC is not significantly related to total SOC storage. At both study sites the 30-100 cm SOC storage is more important for the total SOC storage than the 0-30 cm interval, and large portions of the total SOC are stored in the permafrost. The largest contribution comes from wetland pedons, but highly cryoturbated individual non-wetland pedons can match these. In Kytalyk the landscape partitioning of SOC mostly follows large scale geomorphological features, while in Spasskaya pad forest type also has a large influence.

High-Resolution Remote Sensing and Stable Isotope Patterns Across Heath-Shrub-Forest Ecotone at Abisko and Vassijaure, Northern Sweden

NASA Astrophysics Data System (ADS)

Schwan, M. R.; Herrick, C.; Hobbie, E. A.; Chen, J.; Varner, R. K.; Palace, M. W.; Marek, E.; Kashi, N. N.; Smith, S. L.

2015-12-01

Rapid warming in arctic and sub-arctic environments shifts plant community structure which in turn can alter carbon cycling by releasing large stocks of carbon sequestered in arctic soils. Much work has been done in sub-arctic peatlands to understand how shifts in dominant vegetation cover can ultimately affect global carbon balances, but less focus has been given to upland environments where similar changes are occurring. Recent circumpolar expansion of deciduous shrubs and trees in sub-arctic upland environments may alter carbon cycling due to shrubs and trees sequestering less C in soils than the heath plants they typically replace. In this study we explored the relationship between nutrient and carbon cycling and above-ground vegetation on six transects which traverse an ecotone gradient from heath tundra (dominated by ericoid mycorrhizal plants) through deciduous shrubs to deciduous trees (dominated by ectomycorrhizal plants) in upland environments of sub-arctic Sweden near Vassijaure (~850 mm precipitation) and Abisko (~300 mm precipitation). We collected soil and foliage for analysis of natural abundances of stable carbon and nitrogen isotopes (δ13C and δ15N), which can be a sensitive indicator of C and N dynamics. We also took high-resolution remote aerial imagery over the transects to calculate percent cover of vegetation types using GIS software. We concurrently estimated percent cover in smaller plots on the ground of three dominant species, Empetrum nigrum, Betula nana, and Betula pubescens, to serve as ground-truthing for the aerial imagery. Analysis of vegetation cover data shows significant differences in vegetation types along the transects. Preliminary multiple regression analysis of isotopes shows that δ13C in organic soil at the Vassijaure site is mostly controlled by distance along the transect, an interaction term between transect distance and soil depth, and δ15N (adjusted r2 = 0.85, p < 0.0001). Values of δ13C were lower in soils in the shrubs and forest than in the heath. In regression analyses, δ15N was primarily controlled by depth, and secondarily by heath cover (adjusted r2 = 0.68, p < 0.0001). These results suggest that trees and shrubs are sequestering carbon, and interactions between plants and belowground soil communities may be driving nitrogen dynamics.

Critical zone properties control the fate of nitrogen during experimental rainfall in montane forests of the Colorado Front Range

USGS Publications Warehouse

Hinckley, Eve-Lyn S.; Ebel, Brian A.; Barnes, Rebecca T.; Murphy, Sheila F.; Anderson, Suzanne P.

2017-01-01

Several decades of research in alpine ecosystems have demonstrated links among the critical zone, hydrologic response, and the fate of elevated atmospheric nitrogen (N) deposition. Less research has occurred in mid-elevation forests, which may be important for retaining atmospheric N deposition. To explore the fate of N in the montane zone, we conducted plot-scale experimental rainfall events across a north–south transect within a catchment of the Boulder Creek Critical Zone Observatory. Rainfall events mimicked relatively common storms (20–50% annual exceedance probability) and were labeled with 15N-nitrate (NO3−">NO−3NO3−) and lithium bromide tracers. For 4 weeks, we measured soil–water and leachate concentrations of Br−, 15NO3−,">15NO−3,15NO3−, and NO3−">NO−3NO3− daily, followed by recoveries of 15N species in bulk soils and microbial biomass. Tracers moved immediately into the subsurface of north-facing slope plots, exhibiting breakthrough at 10 and 30 cm over 22 days. Conversely, little transport of Br− or 15NO3−">15NO−315NO3− occurred in south-facing slope plots; tracers remained in soil or were lost via pathways not measured. Hillslope position was a significant determinant of soil 15N-NO3−">NO−3NO3− recoveries, while soil depth and time were significant determinants of 15N recovery in microbial biomass. Overall, 15N recovery in microbial biomass and leachate was greater in upper north-facing slope plots than lower north-facing (toeslope) and both south-facing slope plots in August; by October, 15N recovery in microbial N biomass within south-facing slope plots had increased substantially. Our results point to the importance of soil properties in controlling the fate of N in mid-elevation forests during the summer season.

Integrated Sampling Strategy (ISS) Guide

Treesearch

Robert E. Keane; Duncan C. Lutes

2006-01-01

What is an Integrated Sampling Strategy? Simply put, it is the strategy that guides how plots are put on the landscape. FIREMON’s Integrated Sampling Strategy assists fire managers as they design their fire monitoring project by answering questions such as: What statistical approach is appropriate for my sample design? How many plots can I afford? How many plots do I...

Correlation of prostaglandin E2 concentrations in synovial fluid with ground reaction forces and clinical variables for pain or inflammation in dogs with osteoarthritis induced by transection of the cranial cruciate ligament.

PubMed

Trumble, Troy N; Billinghurst, R Clark; McIlwraith, C Wayne

2004-09-01

To evaluate the temporal pattern of prostaglandin (PG) E2 concentrations in synovial fluid after transection of the cranial cruciate ligament (CCL) in dogs and to correlate PGE2 concentrations with ground reaction forces and subjective clinical variables for lameness or pain. 19 purpose-bred adult male Walker Hounds. Force plate measurements, subjective clinical analysis of pain or lameness, and samples of synovial fluid were obtained before (baseline) and at various time points after arthroscopic transection of the right CCL. Concentrations of PGE2 were measured in synovial fluid samples, and the PGE2 concentrations were correlated with ground reaction forces and clinical variables. The PGE2 concentration increased significantly above the baseline value throughout the entire study, peaking 14 days after transection. Peak vertical force and vertical impulse significantly decreased by day 14 after transection, followed by an increase over time without returning to baseline values. All clinical variables (eg, lameness, degree of weight bearing, joint extension, cumulative pain score, effusion score, and total protein content of synovial fluid, except for WBC count in synovial fluid) increased significantly above baseline values. Significant negative correlations were detected between PGE2 concentrations and peak vertical force (r, -0.5720) and vertical impulse (r, -0.4618), and significant positive correlations were detected between PGE2 concentrations and the subjective lameness score (r, 0.5016) and effusion score (r, 0.6817). Assessment of the acute inflammatory process by measurement of PGE2 concentrations in synovial fluid may be correlated with the amount of pain or lameness in dogs.

Impacts of overgrazing in a long term traditional grazing ecosystem on vegetation around watering points in a semi-arid rangeland of North-Eastern Iran.

PubMed

Hassani, N; Asghari, H R; Frid, A S; Nurberdief, M

2008-07-01

In this study, the effects of livestock overgrazing on vegetation of the critical area around livestock watering points in a traditional grazing ecosystem was investigated on a semi-arid rangeland in North-East of Iran. Transects were placed in 8 geographical directions around watering points and samples were taken systematically. In each experimental plot, 4 m2, percentage of canopy cover, abundance, density and species richness of vegetation were calculated. The results of this study showed that the percentage of canopy cover, density and species richness were changed with distance from watering points. Critical area immediately adjacent to watering points was dominated by unpalatable Peganum harmala and contained of ruderal species such as Sophora sp. Adjacent to this was a zone dominated by species of low palatability such as Acantholimon sp. and Hulthemia persica. In areas most distant from watering points relative importance of moderately palatable species such as Artemisia herba-alba increased. These results show the negative impacts of overgrazing on vegetation and palatability in a traditional grazing ecosystem, which may indicate the necessity of a monitoring programme, to manage livestock grazing and watering points in North-East of Iran.

Contrasting elevational diversity patterns for soil bacteria between two ecosystems divided by the treeline.

PubMed

Li, Guixiang; Xu, Guorui; Shen, Congcong; Tang, Yong; Zhang, Yuxin; Ma, Keming

2016-11-01

Above- and below-ground organisms are closely linked, but how elevational distribution pattern of soil microbes shifting across the treeline still remains unknown. Sampling of 140 plots with transect, we herein investigated soil bacterial distribution pattern from a temperate forest up to a subalpine meadow along an elevational gradient using Illumina sequencing. Our results revealed distinct elevational patterns of bacterial diversity above and below the treeline in responding to changes in soil conditions: a hollow elevational pattern in the forest (correlated with soil temperature, pH, and C:N ratio) and a significantly decreasing pattern in the meadow (correlated with soil pH, and available phosphorus). The bacterial community structure was also distinct between the forest and meadow, relating to soil pH in the forest and soil temperature in the meadow. Soil bacteria did not follow the distribution pattern of herb diversity, but bacterial community structure could be predicted by herb community composition. These results suggest that plant communities have an important influence on soil characteristics, and thus change the elevational distribution of soil bacteria. Our findings are useful for future assessments of climate change impacts on microbial community.

Diversity and Abundance of Chlorophyta in Krakal Beach, Gunung Kidul, Yogyakarta

NASA Astrophysics Data System (ADS)

Putri, A. C.; Nugroho, I. C.; Firdaus, N. U. N.; Puspita, N. O. J.; Fajrin, S. A. R.; Hamzah, S. D. A.

2017-10-01

Chlorophyta plays an important role in energy flow as the main producer in marine food chain, material circulation, bioaccumulation, and bio-indicator in the intertidal zone. Several genera of Chlorophyta have been used by local society around coastal area of Gunung Kidul, Yogyakarta as local product, but the research about diversity and abundance information of Chlorophyta in Krakal beach was not yet understood. The aim of this study is to gain the information about diversity and abundancy of Chlorophyta in Krakal Beach, Gunung Kidul,Yogyakarta. This research was conducted in March 11th 2017. This research utilizes Line Transect and Stratified Random Sampling method which is used 1x1 m plot. There are six genera of Chlorophyta have been identified in this research, such as Chaetomorpha sp.; Boergesenia sp; Ulva sp.; Cladophora sp.; Enteromorpha sp.; and Halicystis sp. From 6 genera of Chlorophyta, the highest genera coverage is Enteromorpha sp. (9.88%). This research is expected to record data of macroalgae abundance especially Chlorophyta, in Krakal Beach. By this research, monitoring of macroalgae could be done and supported by government and local people to maintain the sustainability of Chlorophyta.

Use of burrow entrances to indicate densities of Townsend's ground squirrels

USGS Publications Warehouse

Van Horne, Beatrice; Schooley, Robert L.; Knick, Steven T.; Olson, G.S.; Burnham, K.P.

1997-01-01

Counts of burrow entrances have been positively correlated with densities of semi-fossorial rodents and used as an index of densities. We evaluated their effectiveness in indexing densities of Townsend's ground squirrels (Spermophilus townsendii) in the Snake River Birds of Prey National Conservation Area (SRBOPNCA), Idaho, by comparing burrow entrance densities to densities of ground squirrels estimated from livetrapping in 2 consecutive years over which squirrel populations declined by >75%. We did not detect a consistent relation between burrow entrance counts and ground squirrel density estimates within or among habitat types. Scatter plots indicated that burrow entrances had little predictive power at intermediate densities. Burrow entrance counts did not reflect the magnitude of a between-year density decline. Repeated counts of entrances late in the squirrels' active season varied in a manner that would be difficult to use for calibration of transects sampled only once during this period. Annual persistence of burrow entrances varied between habitats. Trained observers were inconsistent in assigning active-inactive status to entrances. We recommend that burrow entrance counts not be used as measures or indices of ground squirrel densities in shrubsteppe habitats, and that the method be verified thoroughly before being used in other habitats.

Geographic distributions and ecology of ornamental Curcuma (Zingiberaceae) in Northeastern Thailand.

PubMed

Khumkratok, Sutthira; Boongtiang, Kriangsuk; Chutichudet, Prasit; Pramaul, Pairot

2012-10-01

The genus Curcuma is a very important economic plant. Members of this genus were used as food, medicine and ornament plants. The objectives of this study were to examine the geographic distributions and ecological conditions in the natural habitats of Curcuma in Northeastern Thailand. Species diversity was examined using the line transect method. Ecological conditions of the species were examined using a sampling plot of 20 x 20 m. A total of five species were found including Curcuma angustifolia Roxb., C. alismatifolia Gagnep., C. gracillima Gagnep., C. parviflora Wall. and C. rhabdota. These species were in an altitudinal range between 290 m and 831 m above sea level. Four species (C. angustifolia, C. alismatifolia, C. gracillima and C. rhabdota) were distributed in open gaps in dry dipterocarp forest. One species, C. parviflora was found in the contact zone between dry dipterocarp and bamboo (Gigantochloa sp.) forest. C. rhabdota was found only in a habitat with high humidity and shading along the Thailand-Lao PDR border. Significant ecological conditions of the natural habitats of these Curcuma species were identified. Altitude is the most important factor when determining the geographic distributions of these Curcuma species in Northeastern Thailand.

Sampling procedures for inventory of commercial volume tree species in Amazon Forest.

PubMed

Netto, Sylvio P; Pelissari, Allan L; Cysneiros, Vinicius C; Bonazza, Marcelo; Sanquetta, Carlos R

2017-01-01

The spatial distribution of tropical tree species can affect the consistency of the estimators in commercial forest inventories, therefore, appropriate sampling procedures are required to survey species with different spatial patterns in the Amazon Forest. For this, the present study aims to evaluate the conventional sampling procedures and introduce the adaptive cluster sampling for volumetric inventories of Amazonian tree species, considering the hypotheses that the density, the spatial distribution and the zero-plots affect the consistency of the estimators, and that the adaptive cluster sampling allows to obtain more accurate volumetric estimation. We use data from a census carried out in Jamari National Forest, Brazil, where trees with diameters equal to or higher than 40 cm were measured in 1,355 plots. Species with different spatial patterns were selected and sampled with simple random sampling, systematic sampling, linear cluster sampling and adaptive cluster sampling, whereby the accuracy of the volumetric estimation and presence of zero-plots were evaluated. The sampling procedures applied to species were affected by the low density of trees and the large number of zero-plots, wherein the adaptive clusters allowed concentrating the sampling effort in plots with trees and, thus, agglutinating more representative samples to estimate the commercial volume.

Water-level, borehole geophysical log, and water-quality data from wells transecting the freshwater/saline-water interface of the San Antonio segment of the Edwards Aquifer, South-Central Texas, 1999-2007

USGS Publications Warehouse

Lambert, Rebecca B.; Hunt, Andrew G.; Stanton, Gregory P.; Nyman, Michael B.

2009-01-01

As a part of a 9-year (1999-2007) study done by the U.S. Geological Survey in cooperation with the San Antonio Water System to improve understanding of the San Antonio segment of the Edwards aquifer, south-central Texas, in and near the freshwater/saline-water transition zone of the aquifer, the U.S. Geological Survey collected water-level, borehole geophysical, and water-quality data during 1999-2007 from 37 wells arranged in nine transects (except for two wells) across the freshwater/saline-water interface of the aquifer. This report presents the data collected and also describes the data-collection, analytical, and quality-assurance methods used. The wells, constructed with casing from land surface into the upper part of the aquifer and completed as open hole in the aquifer, are in Uvalde County (East Uvalde transect), in Medina County (South Medina and Devine wells), in Bexar County (Pitluk, Mission, and San Antonio transects), in Comal and Guadalupe Counties (Tri-County transect), in Comal County (New Braunfels transect), and in Hays County (Fish Hatchery, San Marcos, and Kyle transects). Data collected included continuous water level at 18 wells; fluid electrical conductivity and temperature with depth (fluid profiles) obtained by borehole geophysical logging of 15 wells; discrete (periodic) samples for major ions and trace elements at 36 wells; stable isotopes or stable isotopes and tritium at 27 wells; dissolved gases obtained by pumping (or collecting flow) of 19 wells; and continuous specific conductance and temperature at three of the wells equipped with continuous water-level sensors.

Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats

PubMed Central

Wallrichs, Megan A.; Ober, Holly K.; McCleery, Robert A.

2017-01-01

Due to increasing threats facing bats, long-term monitoring protocols are needed to inform conservation strategies. Effective monitoring should be easily repeatable while capturing spatio-temporal variation. Mobile acoustic driving transect surveys (‘mobile transects’) have been touted as a robust, cost-effective method to monitor bats; however, it is not clear how well mobile transects represent dynamic bat communities, especially when used as the sole survey approach. To assist biologists who must select a single survey method due to resource limitations, we assessed the effectiveness of three acoustic survey methods at detecting species richness in a vast protected area (Everglades National Park): (1) mobile transects, (2) stationary surveys that were strategically located by sources of open water and (3) stationary surveys that were replicated spatially across the landscape. We found that mobile transects underrepresented bat species richness compared to stationary surveys across all major vegetation communities and in two distinct seasons (dry/cool and wet/warm). Most critically, mobile transects failed to detect three rare bat species, one of which is federally endangered. Spatially replicated stationary surveys did not estimate higher species richness than strategically located stationary surveys, but increased the rate at which species were detected in one vegetation community. The survey strategy that detected maximum species richness and the highest mean nightly species richness with minimal effort was a strategically located stationary detector in each of two major vegetation communities during the wet/warm season. PMID:29134138

West margin of North America - A synthesis of recent seismic transects

USGS Publications Warehouse

Fuis, G.S.

1998-01-01

A comparison of the deep structure along nine recent transects of the west margin of North America shows many important similarities and differences. Common tectonic elements identified in the deep structure along these transects include actively subducting oceanic crust, accreted oceanic/arc (or oceanic-like) lithosphere of Mesozoic through Cenozoic ages. Cenozoic accretionary prisms, Mesozoic accretionary prisms, backstops to the Mesozoic prisms, and undivided lower crust. Not all of these elements are present along all transects. In this study, nine transects, including four crossing subduction zones and five crossing transform faults, are plotted at the same scale and vertical exaggeration (V.E. 1:1), using the above scheme for identifying tectonic elements. The four subduction-zone transects contain actively subducting oceanic crust. Cenozoic accretionary prisms, and bodies of basaltic rocks accreted in the Cenozoic, including remnants of a large, oceanic plateau in the Oregon and Vancouver Island transects. Rocks of age and composition (Eocene basalt) similar to the oceanic plateau are currently subducting in southern Alaska, where they are doubled up on top of Pacific oceanic crust and have apparently created a giant asperity, or impediment to subduction. Most of the subduction-zone transects also contain Mesozoic accretionary prisms, and two of them, Vancouver Island and Alaska, also contain thick, technically underplated bodies of late Mesozoic/early Cenozoic oceanic lithosphere, interpreted as fragments of the extinct Kula plate. In the upper crust, most of the five transform-fault transects (all in California) reflect: (1) tectonic wedging of a Mesozoic accretionary prism into a backstop, which includes Mesozoic/early Cenozoic forearc rocks and Mesozoic ophiolitic/arc basement rocks: and (2) shuffling of the subduction margin of California by strike-slip faulting. In the lower crust, they may reflect migration of the Mendocino triple junction northward (seen in rocks east of the San Andreas fault) and cessation of Farallon-plate subduction (seen in rocks west of the San Andreas fault). In northern California, lower-crustal rocks east of the San Andreas fault have oceanic-crustal velocity and thickness and contain patches of high reflectivity. They may represent basaltic rocks magmatically underplated in the wake of the migration of the Mendocino triple junction, or they may represent stalled, subducted fragments of the Farallon/Gorda plate. The latter alternative does not fit the accepted 'slabless window' model for the migration of the triple junction. This lower-crustal layer and the Moho are offset at the San Andreas and Maacama faults. In central California, a similar lower-crustal layer is observed west of the San Andreas fault. West of the continental slope, it is Pacitic oceanic crust, but beneath the continent it may represent either Pacific oceanic crust, stalled, subducted fragments (microplates) of the Farallon plate, or basaltic rocks magmatically underplated during subduction of the Pacific/Farallon ridge or during breakup of the subducted Farallon plate. The transect in southern California is only partly representative of regional structure, as the structure here is 3-dimensional. In the upper crust, a Mesozoic prism has been thrust beneath crystalline basement rocks of the San Gabriel Mountains and Mojave Desert. In the mid-crust, a bright reflective zone is interpreted as a possible 'master' decollement that can be traced from the fold-and-thrust belt of the Los Angeles basin northward to at least the San Andreas fault. A Moho depression beneath the San Gabriel Mountains is consistent with downwelling of lithospheric mantle beneath the Transverse Ranges that appears to be driving the compression across the Transverse Ranges and Los Angeles basin. ?? 1998 Elsevier Science B.V. All rights reserved.

Evidence of divergent selection for drought and cold tolerance at landscape and local scales in Abies alba Mill. in the French Mediterranean Alps.

PubMed

Roschanski, Anna M; Csilléry, Katalin; Liepelt, Sascha; Oddou-Muratorio, Sylvie; Ziegenhagen, Birgit; Huard, Frédéric; Ullrich, Kristian K; Postolache, Dragos; Vendramin, Giovanni G; Fady, Bruno

2016-02-01

Understanding local adaptation in forest trees is currently a key research and societal priority. Geographically and ecologically marginal populations provide ideal case studies, because environmental stress along with reduced gene flow can facilitate the establishment of locally adapted populations. We sampled European silver fir (Abies alba Mill.) trees in the French Mediterranean Alps, along the margin of its distribution range, from pairs of high- and low-elevation plots on four different mountains situated along a 170-km east-west transect. The analysis of 267 SNP loci from 175 candidate genes suggested a neutral pattern of east-west isolation by distance among mountain sites. F(ST) outlier tests revealed 16 SNPs that showed patterns of divergent selection. Plot climate was characterized using both in situ measurements and gridded data that revealed marked differences between and within mountains with different trends depending on the season. Association between allelic frequencies and bioclimatic variables revealed eight genes that contained candidate SNPs, of which two were also detected using F(ST) outlier methods. All SNPs were associated with winter drought, and one of them showed strong evidence of selection with respect to elevation. Q(ST)-F(ST) tests for fitness-related traits measured in a common garden suggested adaptive divergence for the date of bud flush and for growth rate. Overall, our results suggest a complex adaptive picture for A. alba in the southern French Alps where, during the east-to-west Holocene recolonization, locally advantageous genetic variants established at both the landscape and local scales. © 2015 John Wiley & Sons Ltd.

Log sampling methods and software for stand and landscape analyses.

Treesearch

Lisa J. Bate; Torolf R. Torgersen; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

2008-01-01

We describe methods for efficient, accurate sampling of logs at landscape and stand scales to estimate density, total length, cover, volume, and weight. Our methods focus on optimizing the sampling effort by choosing an appropriate sampling method and transect length for specific forest conditions and objectives. Sampling methods include the line-intersect method and...

Enhancing fish Underwater Visual Census to move forward assessment of fish assemblages: An application in three Mediterranean Marine Protected Areas

PubMed Central

Thiriet, Pierre; Di Franco, Antonio; Francour, Patrice

2017-01-01

Monitoring fish assemblages is needed to assess whether Marine Protected Areas (MPAs) are meeting their conservation and fisheries management goals, as it allows one to track the progress of recovery of exploited species and associated communities. Underwater Visual Census techniques (UVC) are used to monitor fish assemblages in MPAs. UVCs should be adapted to fish abundance, body-size and behaviour, which can strongly affect fish detectability. In Mediterranean subtidal habitats, however, UVC strip transects of one surface area (25x5 m2) are commonly used to survey the whole fish assemblage, from large shy fish to small crypto-benthic fish. Most high trophic level predators (HTLPs) are large shy fish which rarely swim close to divers and, consequently, their abundance may be under-estimated with commonly used transects. Here, we propose an improvement to traditional transect surveys to better account for differences in behaviour among and within species. First, we compared the effectiveness of combining two transect surface areas (large: 35x20 m2; medium: 25x5 m2) in quantifying large, shy fish within and outside Mediterranean MPAs. We identified species-specific body-size thresholds defining a smaller and a larger size class better sampled by medium and large transects respectively. Combining large and medium transects provided more accurate biomass and species richness estimates for large, shy species than using medium transects alone. We thus combined the new approach with two other transect surface areas commonly used to survey crypto-benthic (10x1 m2) and necto-benthic (25x5 m2) species in order to assess how effectively MPAs protection the whole fish assemblage. We verified that MPAs offer significant protection for HTLPs, their response in terms of biomass and density increase in MPAs was always higher in magnitude than other functional groups. Inside MPAs, the contribution of HTLP reached >25% of total fish biomass, against < 2% outside MPAs. Surveys with multiple transect surface areas allow for a more realistic assessment of the structure of the whole fish assemblage and better assessment of potential recovery of HTLPs within reserves of HTLP. PMID:28594836

Enhancing fish Underwater Visual Census to move forward assessment of fish assemblages: An application in three Mediterranean Marine Protected Areas.

PubMed

Prato, Giulia; Thiriet, Pierre; Di Franco, Antonio; Francour, Patrice

2017-01-01

Monitoring fish assemblages is needed to assess whether Marine Protected Areas (MPAs) are meeting their conservation and fisheries management goals, as it allows one to track the progress of recovery of exploited species and associated communities. Underwater Visual Census techniques (UVC) are used to monitor fish assemblages in MPAs. UVCs should be adapted to fish abundance, body-size and behaviour, which can strongly affect fish detectability. In Mediterranean subtidal habitats, however, UVC strip transects of one surface area (25x5 m2) are commonly used to survey the whole fish assemblage, from large shy fish to small crypto-benthic fish. Most high trophic level predators (HTLPs) are large shy fish which rarely swim close to divers and, consequently, their abundance may be under-estimated with commonly used transects. Here, we propose an improvement to traditional transect surveys to better account for differences in behaviour among and within species. First, we compared the effectiveness of combining two transect surface areas (large: 35x20 m2; medium: 25x5 m2) in quantifying large, shy fish within and outside Mediterranean MPAs. We identified species-specific body-size thresholds defining a smaller and a larger size class better sampled by medium and large transects respectively. Combining large and medium transects provided more accurate biomass and species richness estimates for large, shy species than using medium transects alone. We thus combined the new approach with two other transect surface areas commonly used to survey crypto-benthic (10x1 m2) and necto-benthic (25x5 m2) species in order to assess how effectively MPAs protection the whole fish assemblage. We verified that MPAs offer significant protection for HTLPs, their response in terms of biomass and density increase in MPAs was always higher in magnitude than other functional groups. Inside MPAs, the contribution of HTLP reached >25% of total fish biomass, against < 2% outside MPAs. Surveys with multiple transect surface areas allow for a more realistic assessment of the structure of the whole fish assemblage and better assessment of potential recovery of HTLPs within reserves of HTLP.

Persulfate injection into a gasoline source zone

NASA Astrophysics Data System (ADS)

Sra, Kanwartej S.; Thomson, Neil R.; Barker, Jim F.

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O82 -, SO42 -, Na+, dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for > 10 months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in M indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M increased by > 100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone.

Latitudinal transects in the southeastern Pacific Ocean reveal a diverse but patchy distribution of phycotoxins.

PubMed

Trefault, N; Krock, B; Delherbe, N; Cembella, A; Vásquez, M

2011-10-01

Phycotoxin distribution and abundance was determined during an oceanographic expedition along a latitudinal transect of 27° extent in the southeastern Pacific Ocean, from the fjords of Tierra del Fuego Island to offshore Copiapó in the Atacama region along the Chilean coast. Plankton samples were harvested at regular intervals during the entire cruise and later analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for domoic acid (DA) and lipophilic toxins. Although no evident toxic algal bloom was encountered during this transect, several phycotoxin analogues from distinct toxin groups were detected. These phycotoxins included DA, the pectenotoxins PTX-2, PTX-2sa and PTX-11, dinophystoxin-1 (DTX-1) and gymnodimine (GYM), which is the first report of this latter toxin in the southeast Pacific. A region-specific and rather disjunct distribution of GYM, DA and DTX-1 was observed, whereas PTX-2, PTX-2sa and PTX-11 were more widely distributed over almost the entire transect. This work represents the first assessment of lipophilic toxins through a wide latitudinal transect of the southeastern Pacific, revealing a patchy distribution of several phycotoxins and pointing out the specific geographical distribution of the putative toxigenic organisms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Maintaining a permanent plot data base for growth and yield research: Solutions to some recurring problems

Treesearch

John C. Byrne

1993-01-01

Methods for solving some recurring problems of maintaining a permanent plot data base for growth and yield reseuch are described. These methods include documenting data from diverse sampling designs, changing sampling designs, changing field procedures, and coordinating activities in the plots with the land management agency. Managing a permanent plot data base (...

36 CFR 9.42 - Well records and reports, plots and maps, samples, tests and surveys.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Well records and reports, plots and maps, samples, tests and surveys. Any technical data gathered... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Well records and reports, plots and maps, samples, tests and surveys. 9.42 Section 9.42 Parks, Forests, and Public Property...

Are Adult Crambid Snout Moths (Crambinae) and Larval Stages of Lepidoptera Suitable Tools for an Environmental Monitoring of Transgenic Crops? — Implications of a Field Test

PubMed Central

Lang, Andreas; Dolek, Matthias; Theißen, Bernhard; Zapp, Andreas

2011-01-01

Butterflies and moths (Lepidoptera) have been suggested for the environmental monitoring of genetically modified (GM) crops due to their suitability as ecological indicators, and because of the possible adverse impact of the cultivation of current transgenic crops. The German Association of Engineers (VDI) has developed guidelines for the standardized monitoring of Lepidoptera describing the use of light traps for adult moths, transect counts for adult butterflies, and visual search for larvae. The guidelines suggest recording adults of Crambid Snout Moths during transect counts in addition to butterflies, and present detailed protocols for the visual search of larvae. In a field survey in three regions of Germany, we tested the practicability and effort-benefit ratio of the latter two VDI approaches. Crambid Snout Moths turned out to be suitable and practical indicators, which can easily be recorded during transect counts. They were present in 57% of the studied field margins, contributing a substantial part to the overall Lepidoptera count, thus providing valuable additional information to the monitoring results. Visual search of larvae generated results in an adequate effort-benefit ratio when searching for lepidopteran larvae of common species feeding on nettles. Visual search for larvae living on host plants other than nettles was time-consuming and yielded much lower numbers of recorded larvae. Beating samples of bushes and trees yielded a higher number of species and individuals. This method is especially appropriate when hedgerows are sampled, and was judged to perform intermediate concerning the relationship between invested sampling effort and obtained results for lepidopteran larvae. In conclusion, transect counts of adult Crambid Moths and recording of lepidopteran larvae feeding on nettles are feasible additional modules for an environmental monitoring of GM crops. Monitoring larvae living on host plants other than nettles and beating samples of bushes and trees can be used as a supplementary tool if necessary or desired. PMID:26467735

High Resolution Observations of Dissolved Iron Distribution Along a Coastal Offshore Transect in the Eastern North Atlantic.

NASA Astrophysics Data System (ADS)

Blain, S.; Laes, A.; Laan, P.; Achterberg, E.; de Baar, H.

2002-12-01

In order to better understand and quantify the inputs of iron from below in the water column a detailed section from the coast to offshore has been studied in the eastern North Atlantic. The section, extended from 47°36 58 N, 4°14 51 W (depth 96 m) to 46°00 00 N, 8°00 00 W (depth 4912 m). The cruise took place in March 2002, on board R/V Pelagia, as part of the European Union project IRONAGES. Fifteen stations have been sampled for dissolved iron (DFe) and nutrients analysis. Go Flo bottles mounted on a kevlar cable were used for clean seawater sampling in the water column. A torpedo fish and trace metal clean bellows pump were used for surface sampling. Sample were filtered on-line through an 0.2 μm cartridge. The DFe concentrations were measured onboard using a FIA method with on line preconcentration (8-HQ resin) and chemiluminescence detection (mean blank = 28 pM, mean limit of detection= 39 pM). The coastal stations over the shelf showed the highest concentrations of DFe. In this part of the transect, the concentration decreased from the surface to the bottom. Maxima (1-2.4 nM) were associated with increase in turbidity demonstrating the DFe inputs associated with re-suspended sediments and/or pore waters. In the eastern part of the transect, water of the Loire river has been identified has a source of iron. Close to the shelf break the two dimensional iron distribution became more complex. A tidal front, internal waves and slope currents created a patchy distribution of DFe. Evertheless the input from below was always observable at depth between 500 and 1200 m. Finally, in the western part of the transect, off the plateau, the concentration of DFe was strongly correlated with the occurrence of different water masses (see abstract by A. Laës).

Horizonal and Vertical Spatial Patterns of Radon and Other Soil-gases Across the El Pilar Fault Trace at Guaraphiche, Edo. Surce (Venezuela)

NASA Astrophysics Data System (ADS)

LaBrecque, J. J.

2002-05-01

Soil-gases (radon, thoron, carbon dioxide and hydrogen) were measured at 63-cm depths along a transect perpendicular to the rupture (fault trace) from the 1997 Caricao earthquake (Mw=6.9) at Guarapiche, state of Sucre (Venezuela). The transect was about 40 meters long with ten sampling points with the spacings was smaller near the rupture. The shapes of the horizontal spatial patterns for radon (Rn-222), thoron (Rn-220) and total radon (Rn-222+Rn-220) were similar; the gas concentrations increased from both ends of the transect toward the rupture where a dip (valley) occurred. Both carbon dioxide and hydrogen gases showed anomalous values at the same sampling points. Twin peaks (anomalies) had been previously reported and suggested that they were due to blockage in the rupture. We have also determined soil-gases from 25-cm to 155-cm depths near the rupture and at the ends of the transect. The results showed that the soil-gas concentrations were not only higher in the upper levels (less than 65-cm) near the fault trace but were similar or greater than the lower levels. Thus, producing the twin peaks when soil-gas sampling was performed at the 65-cm depth. When the sampling was performed at only 45-cm depth the dip over the rupture was much less and the patterns looked more like a broad doublet peak. In conclusion, one can clearly see that not only positive soil-gas anomalies can occur over a fault trace but also negative ones too. 1) This work was partially funded by a research contract from the Venezuelan National Science Foundation (CONICIT Proyecto S1-95000448). 2) Mailing Address: Centro de Quimica, 8424 NW 56th Street, Suite 00204,Miami, Fl 33166 (USA). E-mail jjlabrec@ivic.ve FAX: +58-212-504-1214

DELTA-13C VALUES OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) COLLECTED FROM TWO CREOSOTE-CONTAMINATED WASTE SITES

EPA Science Inventory

Groundwater samples were collected from the American Creosote Works (ACW) Superfund site in Pensacola, Florida in June and September 1994. Sampling wells were located along a transect leading away from the most contaminated area. PAHs were extracted from the groundwater samples w...

Statistical and Multifractal Evaluation of Soil Compaction in a Vineyard

NASA Astrophysics Data System (ADS)

Marinho, M.; Raposo, J. R.; Mirás Avalos, J. M.; Paz González, A.

2012-04-01

One of the detrimental effects caused by agricultural machines is soil compaction, which can be defined by an increase in soil bulk density. Soil compaction often has a negative impact on plant growth, since it reduces the macroporosity and soil permeability and increases resistance to penetration. Our research explored the effect of the agricultural machinery on soil when trafficking through a vineyard at a small spatial scale, based on the evaluation of the soil compaction status. The objectives of this study were: i) to quantify soil bulk density along transects following wine row, wheel track and outside track, and, ii) to characterize the variability of the bulk density along these transects using multifractal analysis. The field work was conducted at the experimental farm of EVEGA (Viticulture and Enology Centre of Galicia) located in Ponte San Clodio, Leiro, Orense, Spain. Three parallel transects were marked on positions with contrasting machine traffic effects, i.e. vine row, wheel-track and outside-track. Undisturbed samples were collected in 16 points of each transect, spaced 0.50 m apart, for bulk density determination using the cylinder method. Samples were taken in autumn 2011, after grape harvest. Since soil between vine rows was tilled and homogenized beginning spring 2011, cumulative effects of traffic during the vine growth period could be evaluated. The distribution patterns of soil bulk density were characterized by multifractal analysis carried out by the method of moments. Multifractality was assessed by several indexes derived from the mass exponent, τq, the generalized dimension, Dq, and the singularity spectrum, f(α), curves. Mean soil bulk density values determined for vine row, outside-track and wheel-track transects were 1.212 kg dm-3, 1.259 kg dm-3and 1.582 kg dm-3, respectively. The respective coefficients of variation (CV) for these three transects were 7.76%, 4.82% and 2.03%. Therefore mean bulk density under wheel-track was 30.5% higher than along the vine row. Vine row and outside-track positions showed not significant differences between means. The bulk density of the wheel-track transect also showed the lowest CV. The multifractal spectra of the three transects were asymmetric curves, rather short toward the left and much longer toward the right. The width of the right deviating shaped multifractal spectra was ranked as: wine row > outside-track ≈ wheel-track. Entropy dimension, D1, was 0.998, 0.992 and 0.992 for vine row, outside-track and track transects, respectively. These results show different patterns of variability of bulk density for parallel transects. They also suggest that multifractal parameters may be useful in assessing the variability of other soil properties such as soil particle density, soil porosity or soil water content, at different spatial scales as well. Acknowledgments. This work was funded in part by Spanish Ministry of Science and Innovation (MICINN) in the frame of project CGL2009-13700-C02. Financial support from CAPES/GOV., Brazil, is also acknowledged by Prof. M. Marinho.

Comparing Methods of Assessing Dog Rabies Vaccination Coverage in Rural and Urban Communities in Tanzania

PubMed Central

Sambo, Maganga; Johnson, Paul C. D.; Hotopp, Karen; Changalucha, Joel; Cleaveland, Sarah; Kazwala, Rudovick; Lembo, Tiziana; Lugelo, Ahmed; Lushasi, Kennedy; Maziku, Mathew; Mbunda, Eberhard; Mtema, Zacharia; Sikana, Lwitiko; Townsend, Sunny E.; Hampson, Katie

2017-01-01

Rabies can be eliminated by achieving comprehensive coverage of 70% of domestic dogs during annual mass vaccination campaigns. Estimates of vaccination coverage are, therefore, required to evaluate and manage mass dog vaccination programs; however, there is no specific guidance for the most accurate and efficient methods for estimating coverage in different settings. Here, we compare post-vaccination transects, school-based surveys, and household surveys across 28 districts in southeast Tanzania and Pemba island covering rural, urban, coastal and inland settings, and a range of different livelihoods and religious backgrounds. These approaches were explored in detail in a single district in northwest Tanzania (Serengeti), where their performance was compared with a complete dog population census that also recorded dog vaccination status. Post-vaccination transects involved counting marked (vaccinated) and unmarked (unvaccinated) dogs immediately after campaigns in 2,155 villages (24,721 dogs counted). School-based surveys were administered to 8,587 primary school pupils each representing a unique household, in 119 randomly selected schools approximately 2 months after campaigns. Household surveys were conducted in 160 randomly selected villages (4,488 households) in July/August 2011. Costs to implement these coverage assessments were $12.01, $66.12, and $155.70 per village for post-vaccination transects, school-based, and household surveys, respectively. Simulations were performed to assess the effect of sampling on the precision of coverage estimation. The sampling effort required to obtain reasonably precise estimates of coverage from household surveys is generally very high and probably prohibitively expensive for routine monitoring across large areas, particularly in communities with high human to dog ratios. School-based surveys partially overcame sampling constraints, however, were also costly to obtain reasonably precise estimates of coverage. Post-vaccination transects provided precise and timely estimates of community-level coverage that could be used to troubleshoot the performance of campaigns across large areas. However, transects typically overestimated coverage by around 10%, which therefore needs consideration when evaluating the impacts of campaigns. We discuss the advantages and disadvantages of these different methods and make recommendations for how vaccination campaigns can be better monitored and managed at different stages of rabies control and elimination programs. PMID:28352630

Paleo-Productivity across the Paleocene-Eocene Thermal Maximum, Walvis Ridge Transect (ODP Sites 1262, 1263, and 1266)

NASA Astrophysics Data System (ADS)

Chun, C. O.; Delaney, M. L.; Zachos, J. C.

2005-12-01

Walvis Ridge transect (Ocean Drilling Program (ODP) Leg 208) provides the first high-resolution depth-transect of deep-sea sediments recovered from the south Atlantic across the P/E boundary. A geographically restricted depth transect (~ 2.2 km, water depths between 2500 and 4770 m) allows us to constrain the surface waters by assuming marine productivity conditions in the overlying water column are similar across all sites. The sediment record will reveal variations for processes that are water-depth dependent. We use the geochemical tracers; biogenic barium, phosphorus, calcium carbonate, and the redox sensitive trace elements manganese and uranium, to reconstruct nutrient burial, paleoproductivity, and bottom water redox chemistry across the Paleocene-Eocene Thermal Maximum (PETM). We calculate our concentrations on a calcium carbonate-free basis to account for dilution by non-carbonate sediments. Trace metal enrichment factors (EFs) are calculated relative to bulk crustal averages. We chose three sites from the depth transect: the shallowest (Site 1263, 2717 m water depth), an intermediate site (Site 1266, 3798 m water depth), and the deepest site (Site 1262, 4755 m water depth). We sampled each site at a sample resolution of ~ 1-2 kyr for 5 m.y. centered at 55 Ma. Uranium EFs at the shallow site exhibits values ~ 5 pre-event and drop to values near crustal averages during and after the carbon isotope excursion (CIE). No dramatic changes in U EFs across the P/E boundary are recorded at the deep and intermediate sites. Mn EFs range between 2.9 -8.6 prior to the event across all three sites, suggesting an oxygenated depositional environment. At the boundary, Mn EFs drop to crustal averages at all sites, then gradually return to pre-event values, indicating more reducing environments during the CIE, a possible explanation for the benthic extinction event (BEE) observed across this transect. Ba excess and reactive phosphorus exhibit decreased concentrations during the CIE with gradual return to pre-event values at the shallowest and deepest sites. We will compare the paleo-productivity and redox chemistry response at the Walvis Ridge sites across the PETM.

The transect method: a novel approach to on-farm welfare assessment of commercial turkeys

PubMed Central

Marchewka, Joanna; Estevez, Inma; Vezzoli, Giuseppe; Ferrante, Valentina; Makagon, Maja M.

2015-01-01

Currently, no animal-based protocol for on-farm welfare assessment of commercial turkeys is available. The birds’ size and flighty nature make obtaining a representative sample using traditional methods difficult. The transect walks (TW) approach provides a potential alternative for on-farm assessments of turkey welfare. We compared the TW approach with a traditional method, and data collected as the birds were moved out of the house during the load out process (L). Ten commercial 19- to 20-week-old Hybrid turkey flocks were evaluated (1 flock/house/farm). Half of the flocks were housed on farms deemed as “faring well” by the company, the other half were on “suboptimal” farms. Each house was subdivided longitudinally into 4 transects. Two observers walked the transects in random order, recording the total number of birds per transect that were immobile; lame; aggressive towards a mate; interacting with humans; with visible head, vent, or back wounds; engaging in mounting behaviors; small; featherless; dirty; sick; terminal; or dead. Flocks were re-evaluated on the same day using the individual sampling method (S), where randomly selected birds were scored as they took 10 steps. Flocks were re-assessed within 48 h of the transect evaluation, as birds were funneled out of the house during load out. Using ANOVAs we determined the effects of observers, method, management, and their interactions on proportions of turkeys per house within each category. Outcome parameters were not affected by management (P > 0.05 for all) or observer (P > 0.05 for most), but an assessment method effect was detected (P < 0.05). S differed from the 2 other methods (P < 0.05) for most parameters except aggression towards a mate, back wounds, dirty, sick, and vent wounds. Differences were not detected between data collected using TW and during L, except for dead (P = 0.0007) and immobile (P = 0.007). Results suggest that the TW method is a promising tool for on-farm turkey welfare assessment as it produced results similar to those obtained at L when all birds could be scored individually. PMID:25577791

The transect method: a novel approach to on-farm welfare assessment of commercial turkeys.

PubMed

Marchewka, Joanna; Estevez, Inma; Vezzoli, Giuseppe; Ferrante, Valentina; Makagon, Maja M

2015-01-01

Currently, no animal-based protocol for on-farm welfare assessment of commercial turkeys is available. The birds' size and flighty nature make obtaining a representative sample using traditional methods difficult. The transect walks (TW) approach provides a potential alternative for on-farm assessments of turkey welfare. We compared the TW approach with a traditional method, and data collected as the birds were moved out of the house during the load out process (L). Ten commercial 19- to 20-week-old Hybrid turkey flocks were evaluated (1 flock/house/farm). Half of the flocks were housed on farms deemed as "faring well" by the company, the other half were on "suboptimal" farms. Each house was subdivided longitudinally into 4 transects. Two observers walked the transects in random order, recording the total number of birds per transect that were immobile; lame; aggressive towards a mate; interacting with humans; with visible head, vent, or back wounds; engaging in mounting behaviors; small; featherless; dirty; sick; terminal; or dead. Flocks were re-evaluated on the same day using the individual sampling method (S), where randomly selected birds were scored as they took 10 steps. Flocks were re-assessed within 48 h of the transect evaluation, as birds were funneled out of the house during load out. Using ANOVAs we determined the effects of observers, method, management, and their interactions on proportions of turkeys per house within each category. Outcome parameters were not affected by management (P>0.05 for all) or observer (P>0.05 for most), but an assessment method effect was detected (P<0.05). S differed from the 2 other methods (P<0.05) for most parameters except aggression towards a mate, back wounds, dirty, sick, and vent wounds. Differences were not detected between data collected using TW and during L, except for dead (P=0.0007) and immobile (P=0.007). Results suggest that the TW method is a promising tool for on-farm turkey welfare assessment as it produced results similar to those obtained at L when all birds could be scored individually. © The Author 2015. Published by Oxford University Press on behalf of Poultry Science Association.

Forest structure and downed woody debris in boreal, temperate, and tropical forest fragments.

PubMed

Gould, William A; González, Grizelle; Hudak, Andrew T; Hollingsworth, Teresa Nettleton; Hollingsworth, Jamie

2008-12-01

Forest fragmentation affects the heterogeneity of accumulated fuels by increasing the diversity of forest types and by increasing forest edges. This heterogeneity has implications in how we manage fuels, fire, and forests. Understanding the relative importance of fragmentation on woody biomass within a single climatic regime, and along climatic gradients, will improve our ability to manage forest fuels and predict fire behavior. In this study we assessed forest fuel characteristics in stands of differing moisture, i.e., dry and moist forests, structure, i.e., open canopy (typically younger) vs. closed canopy (typically older) stands, and size, i.e., small (10-14 ha), medium (33 to 60 ha), and large (100-240 ha) along a climatic gradient of boreal, temperate, and tropical forests. We measured duff, litter, fine and coarse woody debris, standing dead, and live biomass in a series of plots along a transect from outside the forest edge to the fragment interior. The goal was to determine how forest structure and fuel characteristics varied along this transect and whether this variation differed with temperature, moisture, structure, and fragment size. We found nonlinear relationships of coarse woody debris, fine woody debris, standing dead and live tree biomass with mean annual median temperature. Biomass for these variables was greatest in temperate sites. Forest floor fuels (duff and litter) had a linear relationship with temperature and biomass was greatest in boreal sites. In a five-way multivariate analysis of variance we found that temperature, moisture, and age/structure had significant effects on forest floor fuels, downed woody debris, and live tree biomass. Fragment size had an effect on forest floor fuels and live tree biomass. Distance from forest edge had significant effects for only a few subgroups sampled. With some exceptions edges were not distinguishable from interiors in terms of fuels.

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

NASA Technical Reports Server (NTRS)

Huemmrich, Karl Fred; Gamon, John A.; Tweedie, Craig E.; Campbell, Petya K. Entcheva; Landis, David R.; Middleton, Elizabeth M.

2013-01-01

Non-vascular plants (lichens and mosses) are significant components of tundra landscapes and may respond to climate change differently from vascular plants affecting ecosystem carbon balance. Remote sensing provides critical tools for monitoring plant cover types, as optical signals provide a way to scale from plot measurements to regional estimates of biophysical properties, for which spatial-temporal patterns may be analyzed. Gas exchange measurements were collected for pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow, AK. These functional types were found to have three significantly different values of light use efficiency (LUE) with values of 0.013 plus or minus 0.0002, 0.0018 plus or minus 0.0002, and 0.0012 plus or minus 0.0001 mol C mol (exp -1) absorbed quanta for vascular plants, mosses and lichens, respectively. Discriminant analysis of the spectra reflectance of these patches identified five spectral bands that separated each of these vegetation functional types as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Along the transect, area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. The patch-level statistical discriminant functions applied to in situ hyperspectral reflectance data collected along the transect successfully unmixed cover fractions of the vegetation functional types. The unmixing functions, developed from the transect data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine variability in distribution of the vegetation functional types for an area near Barrow, AK. Spatial variability of LUE was derived from the observed functional type distributions. Across this landscape, a fivefold variation in tundra LUE was observed. LUE calculated from the functional type cover fractions was also correlated to a spectral vegetation index developed to detect vegetation chlorophyll content. The concurrence of these alternate methods suggest that hyperspectral remote sensing can distinguish functionally distinct vegetation types and can be used to develop regional estimates of photosynthetic LUE in tundra landscapes.

Comparison of Two Multifractal Analysis Methods: Generalized Structure Function and Multifractal Spectrum

NASA Astrophysics Data System (ADS)

Morato, M. Carmen; Castellanos, M. Teresa; Bird, Nigel; Tarquis, Ana M.

2016-04-01

Soil variability has often been a constant expected factor to take in account in soil studies. This variability could be considered to be composed of "functional" variations plus random fluctuations or noise. Multifractal formalism, first proposed by Mandelbrot (1982), is suitable for variables with self-similar distribution on a spatial domain. Multifractal analysis can provide insight into spatial variability of crop or soil parameters. In soil science, it has been quite popular to characterize the scaling property of a variable measured along a transect as a mass distribution of a statistical measure on a length domain of the studied transect. To do this, it divides it into a number of self similar segments and estimate the partition function and mass function. Based on this, the multifractal spectra (MFS) is calculated. However, another technique can be applied focus its attention in the variations of a measure analyzing the moments of the absolute differences at different scales, the Generalized Structure Function (GSF), and extracting the Generalized Hurst exponents. The aim of this study is to compare both techniques in a transect data. A common 1024 m transect across arable fields at Silsoe in Bedfordshire, east-central England were analyzed with these two multifractal methods. Properties studied were total porosity (Porosity), gravimetric water content (GWC) and nitrogen oxide flux (NO2 flux). The results showed in both methods that NO2 flux presents a clear multifractal character and a weak one in the GWC and Porosity cases. Several parameters were calculated from both methods and are discussed. On the other hand, using the partition function all the scale ranges were used, meanwhile in the GSF a shorter range of scales showed linear behavior in the bilog plots used to estimate the parameters. GWC exhibits a linear pattern from increments of 4 till 256 meters, Porosity showed this behavior from 4 till 64 meters. In case of NO2 flux only from 32 to 256 meters showed it. However, the relation between the mass exponent function and the GSF, found in the literature, was positively verified in the three variables.

SPRUCE Peat Physical and Chemical Characteristics from Experimental Plot Cores, 2012

DOE Data Explorer

Iversen, C. M. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hanson, P. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Brice, D. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Phillips, J. R. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; McFarlane, K. J. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Hobbie, E. A. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.; Kolka, R. K. [Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

2012-01-01

This data set reports the results of physical and chemical analyses of peat core samples from the SPRUCE experimental study plots located in the S1-Bog. On August 13-15, 2012, a team of SPRUCE investigators and collaborators collected core samples of peat in the SPRUCE experimental plots. The goal was to characterize the biological, physical, and chemical characteristics of peat, and how those characteristics changed throughout the depth profile of the bog, prior to the initialization of the SPRUCE experimental warming and CO2 treatments. Cores were collected from 16 experimental plots; samples were collected from the hummock and hollow surfaces to depths of 200-300 cm in defined increments. Three replicate cores were collected from both hummock and hollow locations in each plot. The coring locations within each plot were mapped

The detectability of nitrous oxide mitigation efficacy in intensively grazed pastures using a multiple-plot micrometeorological technique

NASA Astrophysics Data System (ADS)

McMillan, A. M. S.; Harvey, M. J.; Martin, R. J.; Bromley, A. M.; Evans, M. J.; Mukherjee, S.; Laubach, J.

2014-05-01

Methodologies are required to verify agricultural greenhouse gas mitigation at scales relevant to farm management. Micrometeorological techniques provide a viable approach for comparing fluxes between fields receiving mitigation treatments and control fields. However, they have rarely been applied to spatially verifying treatments aimed at mitigating nitrous oxide emission from intensively grazed pastoral systems. We deployed a micrometeorological system to compare N2O flux among several ~1.5 ha plots in intensively grazed dairy pasture. The sample collection and measurement system is referred to as the Field-Scale Nitrous Oxide Mitigation Assessment System (FS-NOMAS) and used a tuneable diode laser absorption spectrometer to measure N2O gradients to high precision at four locations along a 300 m transect. The utility of the FS-NOMAS to assess mitigation efficacy depends largely on its ability to resolve very small vertical N2O gradients. The performance of the FS-NOMAS was assessed in this respect in laboratory and field-based studies. The FS-NOMAS could reliably resolve gradients of 0.039 ppb between a height of 0.5 and 1.0 m. The gradient resolution achieved corresponded to the ability to detect an inter-plot N2O flux difference of 26 μg N2O-N m-2 h-1 under the most commonly encountered conditions of atmospheric mixing (quantified here by a turbulent transfer coefficient), but this ranged from 11 to 59 μg N2O-N m-2 h-1 as the transfer coefficient ranged between its 5th and 95th percentile. Assuming a likely value of 100 μg N2O-N m-2 h-1 for post-grazing N2O fluxes from intensively grazed New Zealand dairy pasture, the system described here would be capable of detecting a mitigation efficacy of 26% for a single (40 min) comparison. We demonstrate that the system has considerably greater sensitivity to treatment effects by measuring cumulative fluxes over extended periods.

The detectability of nitrous oxide mitigation efficacy in intensively grazed pastures using a multiple plot micrometeorological technique

NASA Astrophysics Data System (ADS)

McMillan, A. M. S.; Harvey, M. J.; Martin, R. J.; Bromley, A. M.; Evans, M. J.; Mukherjee, S.; Laubach, J.

2013-10-01

Methodologies are required to verify agricultural greenhouse gas mitigation at scales relevant to farm management. Micrometeorological techniques provide a viable approach for comparing fluxes between fields receiving mitigation treatments and control fields. However, they have rarely been applied to spatially verifying treatments aimed at mitigating nitrous oxide emission from intensively grazed pastoral systems. We deployed a micrometeorological system to compare N2O flux among several ~ 1.5 ha plots in intensively grazed dairy pasture. The sample collection and measurement system is referred to as the Field-Scale Nitrous Oxide Mitigation Assessment System (FS-NOMAS) and used a tuneable diode laser absorption spectrometer to measure N2O gradients to high precision at four locations along a 300 m transect. The utility of the FS-NOMAS to assess mitigation efficacy depends largely on its ability to resolve very small vertical N2O gradients. The performance of the FS-NOMAS was assessed in this respect in laboratory and field-based studies. The FS-NOMAS could reliably resolve gradients of 0.039 ppb between a height of 0.5 m and 1.0 m. The gradient resolution achieved corresponded to the ability to detect an inter-plot N2O flux difference of 26.4 μg N2O-N m-2 h-1 under the most commonly encountered conditions of atmospheric mixing (quantified here by a turbulent transfer coefficient), but this ranged from 11 to 59 μg N2O-N m-2 h-1 as the transfer coefficient ranged between its 5th and 95th percentile. Assuming a likely value of 100 μg N2O-N m-2 h-1 for post-grazing N2O fluxes from intensively grazed New Zealand dairy pasture, the system described here would be capable of detecting a mitigation efficacy of 26% for a single (40 min) comparison. We demonstrate that the system has considerably greater sensitivity to treatment effects by measuring cumulative fluxes over extended periods.

Changes in avian and plant communities of aspen woodlands over 12 years after livestock removal in the northwestern Great Basin

USGS Publications Warehouse

Earnst, Susan L.; Dobkin, David S.; Ballard, Jennifer A.

2012-01-01

Riparian and quaking aspen (Populus tremuloides) woodlands are centers of avian abundance and diversity in the western United States, but they have been affected adversely by land use practices, particularly livestock grazing. In 1990, cattle were removed from a 112,500-ha national wildlife refuge in southeastern Oregon. Thereafter, we monitored changes in vegetation and bird abundance in years 1–3 (phase 1) and 10–12 (phase 2) in 17 riparian and 9 snow-pocket aspen plots. On each 1.5-ha plot, we sampled vegetation in 6 transects. Three times during each breeding season, observers recorded all birds 50 m to each side of the plot's 150-m centerline for 25 minutes. We analyzed data with multivariate analysis of variance and paired t tests with p values adjusted for multiple comparisons. In both periods, riparian and snow-pocket aspen produced extensive regeneration of new shoots (x̄ = 2646 stems/ha and 7079 stems/ha, respectively). By phase 2, a 64% increase in medium-diameter trees in riparian stands indicated successful recruitment into the overstory, but this pattern was not seen in snow-pocket stands, where the density of trees was over 2 times greater. By phase 2 in riparian and snow-pocket stands, native forb cover had increased by 68% and 57%, respectively, mesic shrub cover had increased by 29% and 58%, and sagebrush cover had decreased by 24% and 31%. Total avian abundance increased by 33% and 39% in riparian and snow-pocket aspen, respectively, ground or understory nesters increased by 133% and 67% and overstory nesters increased by 34% and 33%. Similarly, ground or understory foragers increased by 25% and 32%, aerial foragers by 55% and 57%, and overstory foragers by 66% and 43%. We interpreted the substantial regeneration of aspen shoots, increased densities of riparian forbs and shrubs, and increased avian abundances as a multitrophic-level response to the total removal of livestock and as substantial movement toward recovery of biological integrity.

Where do the Field Plots Belong? A Multiple-Constraint Sampling Design for the BigFoot Project

NASA Astrophysics Data System (ADS)

Kennedy, R. E.; Cohen, W. B.; Kirschbaum, A. A.; Gower, S. T.

2002-12-01

A key component of a MODIS validation project is effective characterization of biophysical measures on the ground. Fine-grain ecological field measurements must be placed strategically to capture variability at the scale of the MODIS imagery. Here we describe the BigFoot project's revised sampling scheme, designed to simultaneously meet three important goals: capture landscape variability, avoid spatial autocorrelation between field plots, and minimize time and expense of field sampling. A stochastic process places plots in clumped constellations to reduce field sampling costs, while minimizing spatial autocorrelation. This stochastic process is repeated, creating several hundred realizations of plot constellations. Each constellation is scored and ranked according to its ability to match landscape variability in several Landsat-based spectral indices, and its ability to minimize field sampling costs. We show how this approach has recently been used to place sample plots at the BigFoot project's two newest study areas, one in a desert system and one in a tundra system. We also contrast this sampling approach to that already used at the four prior BigFoot project sites.

Variations in Pb concentrations and Pb-isotope ratios in soils collected along an east-west transect across the United States

NASA Astrophysics Data System (ADS)

Smith, David; Woodruff, Laurel; Reimann, Clemens; Flem, Belinda

2014-05-01

Soil A-horizon and C-horizon samples were collected along a 4000 km long transect cutting the USA from the west to the east coast. For purposes of site selection, the transect was divided into approximately 40-km segments. For each segment, a 1-km2 target area was selected at random. Soil A- and C-horizon samples were collected at a site within each target area that was most representative of the surrounding landscape. The samples were air-dried at ambient temperature, disaggregated, and sieved through a 2-mm stainless steel screen. The <2-mm material was crushed to <150 µm in a ceramic mill prior to chemical analysis. Lead was analyzed in all the A- and C-horizon samples by inductively coupled plasma-mass spectrometry following a 4-acid digestion. The complete dataset can be found in Smith et al., 2005. Pb-isotope ratio measurements were carried out on 159 soil A-horizon and 137 soil C-horizon samples on an inductively coupled sector field plasma mass spectrometer (SF-ICP-MS; ELEMENT 1, Finnigan MAT) in the laboratory of the Geological Survey of Norway (NGU), following a 7 N HNO3 digestion. Lead concentrations along the transect show (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for the central to eastern U.S. (Missouri to Maryland) when compared to the western U.S. (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern US (1.35 vs. 1.14). Lead isotopes show a distinct trend across the U.S., with the highest 206Pb/207Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g. California, median A-horizon: 1.195; C-horizon:1.216). The soil C-horizon samples show generally higher 206Pb/207Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The 206Pb/207Pb isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb concentration and 206Pb/207Pb isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes. The results of this study demonstrate that often none of above two requirements for the use of Pb isotopes in environmental sciences will be met. REFERENCES Smith, D.B., Cannon, W.F., Woodruff, L.G., Garrett, R.G., Klassen, R., Kilburn, J.E., Horton, J.D., King, H.D., Goldhaber, M.B., Morrison, J.M., 2005. Major- and trace-element concentrations in soils from two continental-scale transects of the United States and Canada. U.S. Geol. Surv. Open-File Rep. 2005-1253.

Number of pins in two-stage stratified sampling for estimating herbage yield

Treesearch

William G. O' Regan; C. Eugene Conrad

1975-01-01

In a two-stage stratified procedure for sampling herbage yield, plots are stratified by a pin frame in stage one, and clipped. In stage two, clippings from selected plots are sorted, dried, and weighed. Sample size and distribution of plots between the two stages are determined by equations. A way to compute the effect of number of pins on the variance of estimated...

Demonstration of line transect methodologies to estimate urban gray squirrel density

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

Hein, E.W.

1997-11-01

Because studies estimating density of gray squirrels (Sciurus carolinensis) have been labor intensive and costly, I demonstrate the use of line transect surveys to estimate gray squirrel density and determine the costs of conducting surveys to achieve precise estimates. Density estimates are based on four transacts that were surveyed five times from 30 June to 9 July 1994. Using the program DISTANCE, I estimated there were 4.7 (95% Cl = 1.86-11.92) gray squirrels/ha on the Clemson University campus. Eleven additional surveys would have decreased the percent coefficient of variation from 30% to 20% and would have cost approximately $114. Estimatingmore » urban gray squirrel density using line transect surveys is cost effective and can provide unbiased estimates of density, provided that none of the assumptions of distance sampling theory are violated.« less

Richness and cover of nontimber economic plants along altitude in temperate Himalayan forest-use types.

PubMed

Tariq, Akash; Adnan, Muhammad; AbdElsalam, Naser M; Fouad, Hassan; Hussain, Kamran; Ullah, Riaz; Ullah, Ahsan

2014-01-01

Pakistani Himalaya stretches over a wide range of altitudinal gradients and supports high diversity of medicinal plants that are an important source for rural livelihood. Altitudinal effects on ground vegetation have already been indicated but ground vegetation is also under severe threat of grazing and over collection. The present study investigated the effect of altitude on medicinal plants abundance in both old-growth and derived woodland forests. Each of the five line transects was selected in old-growth and derived woodland forests. Each line transect consisted of four plots distributed at four altitudinal levels (2200, 2300, 2400, and 2500 m asl). Species richness under derived woodland had shown strong negative correlation (r = -0.95) with altitude while it was found to be nonsignificant under old-growth. Cover of most of the species such as Veronica laxa (r = -0.95, P ≤ 0.05) had shown significant negative correlation with altitude under derived woodland. Cover abundance of some species like Valeriana jatamansi and Viola canescens has also shown significant negative correlation under old-growth forest. Derived woodland can decrease the cover abundance of valuable medicinal plants towards extension at higher altitudes. Thus, protection of the derived woodland could serve as a tool for the improvement of rural livelihood and ecological restoration.

Richness and Cover of Nontimber Economic Plants along Altitude in Temperate Himalayan Forest-Use Types

PubMed Central

Tariq, Akash; Adnan, Muhammad; AbdElsalam, Naser M.; Fouad, Hassan; Hussain, Kamran; Ullah, Ahsan

2014-01-01

Pakistani Himalaya stretches over a wide range of altitudinal gradients and supports high diversity of medicinal plants that are an important source for rural livelihood. Altitudinal effects on ground vegetation have already been indicated but ground vegetation is also under severe threat of grazing and over collection. The present study investigated the effect of altitude on medicinal plants abundance in both old-growth and derived woodland forests. Each of the five line transects was selected in old-growth and derived woodland forests. Each line transect consisted of four plots distributed at four altitudinal levels (2200, 2300, 2400, and 2500 m asl). Species richness under derived woodland had shown strong negative correlation (r = −0.95) with altitude while it was found to be nonsignificant under old-growth. Cover of most of the species such as Veronica laxa (r = −0.95, P ≤ 0.05) had shown significant negative correlation with altitude under derived woodland. Cover abundance of some species like Valeriana jatamansi and Viola canescens has also shown significant negative correlation under old-growth forest. Derived woodland can decrease the cover abundance of valuable medicinal plants towards extension at higher altitudes. Thus, protection of the derived woodland could serve as a tool for the improvement of rural livelihood and ecological restoration. PMID:25032237

Standardized mean differences cause funnel plot distortion in publication bias assessments.

PubMed

Zwetsloot, Peter-Paul; Van Der Naald, Mira; Sena, Emily S; Howells, David W; IntHout, Joanna; De Groot, Joris Ah; Chamuleau, Steven Aj; MacLeod, Malcolm R; Wever, Kimberley E

2017-09-08

Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, sample size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small sample size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a sample size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results.

Standardized mean differences cause funnel plot distortion in publication bias assessments

PubMed Central

Van Der Naald, Mira; Sena, Emily S; Howells, David W; IntHout, Joanna; De Groot, Joris AH; Chamuleau, Steven AJ; MacLeod, Malcolm R

2017-01-01

Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, sample size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small sample size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a sample size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results. PMID:28884685

New methods for sampling sparse populations

Treesearch

Anna Ringvall

2007-01-01

To improve surveys of sparse objects, methods that use auxiliary information have been suggested. Guided transect sampling uses prior information, e.g., from aerial photographs, for the layout of survey strips. Instead of being laid out straight, the strips will wind between potentially more interesting areas. 3P sampling (probability proportional to prediction) uses...

Detecting spatial structures in throughfall data: the effect of extent, sample size, sampling design, and variogram estimation method

NASA Astrophysics Data System (ADS)

Voss, Sebastian; Zimmermann, Beate; Zimmermann, Alexander

2016-04-01

In the last three decades, an increasing number of studies analyzed spatial patterns in throughfall to investigate the consequences of rainfall redistribution for biogeochemical and hydrological processes in forests. In the majority of cases, variograms were used to characterize the spatial properties of the throughfall data. The estimation of the variogram from sample data requires an appropriate sampling scheme: most importantly, a large sample and an appropriate layout of sampling locations that often has to serve both variogram estimation and geostatistical prediction. While some recommendations on these aspects exist, they focus on Gaussian data and high ratios of the variogram range to the extent of the study area. However, many hydrological data, and throughfall data in particular, do not follow a Gaussian distribution. In this study, we examined the effect of extent, sample size, sampling design, and calculation methods on variogram estimation of throughfall data. For our investigation, we first generated non-Gaussian random fields based on throughfall data with heavy outliers. Subsequently, we sampled the fields with three extents (plots with edge lengths of 25 m, 50 m, and 100 m), four common sampling designs (two grid-based layouts, transect and random sampling), and five sample sizes (50, 100, 150, 200, 400). We then estimated the variogram parameters by method-of-moments and residual maximum likelihood. Our key findings are threefold. First, the choice of the extent has a substantial influence on the estimation of the variogram. A comparatively small ratio of the extent to the correlation length is beneficial for variogram estimation. Second, a combination of a minimum sample size of 150, a design that ensures the sampling of small distances and variogram estimation by residual maximum likelihood offers a good compromise between accuracy and efficiency. Third, studies relying on method-of-moments based variogram estimation may have to employ at least 200 sampling points for reliable variogram estimates. These suggested sample sizes exceed the numbers recommended by studies dealing with Gaussian data by up to 100 %. Given that most previous throughfall studies relied on method-of-moments variogram estimation and sample sizes << 200, our current knowledge about throughfall spatial variability stands on shaky ground.

Detecting spatial structures in throughfall data: The effect of extent, sample size, sampling design, and variogram estimation method

NASA Astrophysics Data System (ADS)

Voss, Sebastian; Zimmermann, Beate; Zimmermann, Alexander

2016-09-01

In the last decades, an increasing number of studies analyzed spatial patterns in throughfall by means of variograms. The estimation of the variogram from sample data requires an appropriate sampling scheme: most importantly, a large sample and a layout of sampling locations that often has to serve both variogram estimation and geostatistical prediction. While some recommendations on these aspects exist, they focus on Gaussian data and high ratios of the variogram range to the extent of the study area. However, many hydrological data, and throughfall data in particular, do not follow a Gaussian distribution. In this study, we examined the effect of extent, sample size, sampling design, and calculation method on variogram estimation of throughfall data. For our investigation, we first generated non-Gaussian random fields based on throughfall data with large outliers. Subsequently, we sampled the fields with three extents (plots with edge lengths of 25 m, 50 m, and 100 m), four common sampling designs (two grid-based layouts, transect and random sampling) and five sample sizes (50, 100, 150, 200, 400). We then estimated the variogram parameters by method-of-moments (non-robust and robust estimators) and residual maximum likelihood. Our key findings are threefold. First, the choice of the extent has a substantial influence on the estimation of the variogram. A comparatively small ratio of the extent to the correlation length is beneficial for variogram estimation. Second, a combination of a minimum sample size of 150, a design that ensures the sampling of small distances and variogram estimation by residual maximum likelihood offers a good compromise between accuracy and efficiency. Third, studies relying on method-of-moments based variogram estimation may have to employ at least 200 sampling points for reliable variogram estimates. These suggested sample sizes exceed the number recommended by studies dealing with Gaussian data by up to 100 %. Given that most previous throughfall studies relied on method-of-moments variogram estimation and sample sizes ≪200, currently available data are prone to large uncertainties.

Vegetation patterns and environmental gradients in coastal meadows on the Yukon-Kuskokwim Delta, Alaska

USGS Publications Warehouse

Kincheloe, Karen L.; Stehn, Robert A.

1991-01-01

Tundra vegetation and environmental variables were sampled on the Yukon–Kuskokwim delta in western Alaska. On transects extending from intertidal mudflat to upland tundra, we estimated cover by vascular plant species, soil moisture, salinity, relative elevation, depth to permafrost, and distance upriver from the coast. Two-way indicator species analysis (TWINSPAN) classified 21 communities. Ordination by detrended correspondence analysis (DECORANA) revealed a gradient correlated with the combination of elevation, permafrost depth, and salinity along the first axis for both upriver and downriver transects.

Persulfate injection into a gasoline source zone.

PubMed

Sra, Kanwartej S; Thomson, Neil R; Barker, Jim F

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O8(2-), SO4(2-), Na(+), dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for >10months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in [Formula: see text] indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M˙DIC increased by >100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone. Copyright © 2013 Elsevier B.V. All rights reserved.

Optimizing variable radius plot size and LiDAR resolution to model standing volume in conifer forests

Treesearch

Ram Kumar Deo; Robert E. Froese; Michael J. Falkowski; Andrew T. Hudak

2016-01-01

The conventional approach to LiDAR-based forest inventory modeling depends on field sample data from fixed-radius plots (FRP). Because FRP sampling is cost intensive, combining variable-radius plot (VRP) sampling and LiDAR data has the potential to improve inventory efficiency. The overarching goal of this study was to evaluate the integration of LiDAR and VRP data....

Environmental parameters of the Tennessee River in Alabama. 1: Thermal stratification

NASA Technical Reports Server (NTRS)

Rosing, L. M.

1976-01-01

Thermal stratification data of a transect across Wheeler Reservoir are correlated with the climatological data at the time of sampling. This portion of the Tennessee River is used as a heat sink for the effluent from the three reactor Browns Ferry Nuclear Power Plant. The transect sampling line is 1.3 miles below this point of effluence. Data are presented by weekly samplings for one year prior to plant operations. Post-operational data are presented with one reactor in operation and with two reactors in partial operation. Data gathering was terminated when the plant ceased operations. The results indicate that the effluent for partial plant operation were inconclusive. As a result, recommendations include continuing the sampling when the plant resumes operation at full capacity. Recommendations also include developing math models with the presented thermal and climatological data to be used for predicting the effluent impact in the river with varying climatological conditions and also to predict the effectiveness of the cooling towers.

Predicting yellow toadflax infestations in the Flat Tops Wilderness of Colorado

USGS Publications Warehouse

Sutton, J.R.; Stohlgren, T.J.; Beck, K.G.

2007-01-01

Understanding species-environment relationships is important to predict the spread of non-native species. Yellow toadflax (Linaria vulgaris Mill.) is an invasive perennial recently found in the Flat Tops Wilderness of the White River National Forest on the western slope of the Colorado Rocky Mountains. We hypothesized yellow toadflax occurrence could be predicted from easily measured site characteristics. We used logistic regression with stepwise selection to generate a model to predict yellow toadflax occurrence on a particular plot based on that site's physical characteristics. The experimental design was a paired-plot study in two locations using circular 1,018-m2 plots. Sixty-eight plots that did not contain yellow toadflax and 65 plots that contained yellow toadflax were sampled at the Ripple Creek site in 1999. In 2000, 54 non-toadflax plots and 55 toadflax-containing plots were sampled in the Marvine Creek site. Site characteristics sampled included: vegetation type; under-canopy light level; slope; aspect; soil properties; presence of disturbance, trails, and/or water; and total species richness. A model that correctly classified >90% of the 242 plots sampled included two vegetation type parameters, the presence of trails, and total species richness. Yellow toadflax is most often found in areas that were open-canopy sites, along trails, and with higher species diversity plots (>23 species). This approach can be used for other species in other areas to rapidly identify areas vulnerable to invasion. ?? 2007 Springer Science+Business Media, Inc.

The Distribution and Magnitude of Glacial Erosion on 103-year Timescales at Engabreen, Norway

NASA Astrophysics Data System (ADS)

Rand, C.; Goehring, B. M.

2017-12-01

We derive the magnitudes of glacial erosion integrated over 103-year timescales across a transect transverse to the direction of ice flow at Engabreen, Norway. Understanding the distribution of glacial erosion is important for several reasons, including sediment budgeting to fjord environments, development of robust landscape evolution models, and if a better understanding between erosion and ice-bed interface properties (e.g., sliding rate, basal water pressure) can be developed, we can use records of glacial erosion to infer glaciological properties that can ultimately benefit models of past and future glaciers. With few exceptions, measurements of glacial erosion are limited to the historical past and even then are rare owing to the difficulty of accessing the glacier bed. One method proven useful in estimating glacial erosion on 103-year timescales is to measure the remaining concentrations of cosmogenic nuclides that accumulate in exposed bedrock during periods of retracted glacier extent and are removed by glacial erosion and radioactive decay during ice cover. Here we will present measurements of 14C and 10Be measured in proglacial bedrock from Engabreen. Our transects are ca. 600 and 400 meters in front of the modern ice front, and based on historical imagery, was ice covered until the recent past. Initial 10Be results show an increase in concentrations of nearly an order of magnitude from the samples near the center of the glacial trough to those on the lateral margin, consistent with conceptual models of glacial erosion parameterized in terms of sliding velocity. Naïve exposure ages that assume no subglacial erosion range from 0.22 - 9.04 ka. More importantly, we can estimate erosion depths by assuming zero erosion of the highest concentration sample along the two transects and calculate the amount of material removed to yield the lower concentrations elsewhere along the two transects. Results indicate minimum erosion depths of 1-183 cm for most ice proximal transect and 7-56 cm for the more distal one.

Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2003 through 2014

USGS Publications Warehouse

Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

2016-04-25

Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

Ecological Relationships between Meloidogyne spartinae and Salt Marsh Grasses in Connecticut

PubMed Central

Elmer, W. H.

2008-01-01

Healthy specimens of selected grasses were collected from salt marshes and grown in the greenhouse. Plants were inoculated with Meloidogyne spartinae to determine the host range of this nematode. After 12 weeks, Spartina alterniflora plants formed root galls in response to infection and increased M. spartinae populations. Spartina patens, Spartina cynosuroides, Juncus gerardii and Distichlis spicata were non-hosts. In order to determine the natural distribution of M. spartinae in dieback areas, S. alterniflora plants were sampled from transects adjacent to dieback areas in Madison, CT, at low tide. Plants were sampled at the top or the creek and at 1-m intervals to the lowest area of plant growth at the low tide water's edge. Five samples were taken over an elevation drop of 90 cm. Two transects were taken each day on 21 June and 5 July 2007, and one transect was taken on 31 October 2007. Meloidogyne spartinae galls per gram root were higher at the higher elevations. In late June and early July 2007, M. spartinae developed more quickly in the higher elevations, perhaps because peat and sediments were drier and warmer away from low tide water levels. The effects of M. spartinae on S. alterniflora and the role of the nematode in marsh decline and dieback in the northeast United States remain to be determined. PMID:19440262

Optimal design of a plot cluster for monitoring

Treesearch

Charles T. Scott

1993-01-01

Traveling costs incurred during extensive forest surveys make cluster sampling cost-effective. Clusters are specified by the type of plots, plot size, number of plots, and the distance between plots within the cluster. A method to determine the optimal cluster design when different plot types are used for different forest resource attributes is described. The method...

Metadata (MD)

Treesearch

Robert E. Keane

2006-01-01

The Metadata (MD) table in the FIREMON database is used to record any information about the sampling strategy or data collected using the FIREMON sampling procedures. The MD method records metadata pertaining to a group of FIREMON plots, such as all plots in a specific FIREMON project. FIREMON plots are linked to metadata using a unique metadata identifier that is...

Measurement of the Isotopic Signature of Soil Carbon Dioxide: Methods Development and Initial Field Results

NASA Astrophysics Data System (ADS)

Kayler, Z.; Rugh, W.; Mix, A. C.; Bond, B. J.; Sulzman, E. W.

2005-12-01

Soil respiration is a significant component of ecosystem respiration and its isotopic composition is likely to lend insight into ecosystem processes. We have designed probes to determine the isotopic signature of soil-respired CO2 using a two end-member mixing model approach (i.e., Keeling plot). Each probe consists of three 35 ml PVC chambers cased in fiberglass mesh and connected to the soil surface via stainless steel tubing with a septa-lined swagelok fitting. Chambers are vertically connected such that they sample gases at depth intervals centered on 5, 15, and 30 cm. Gases are sampled via a hand vacuum pump equipped with a two-way valve, which allows vials pre-filled with N2 gas in the laboratory to be evacuated and re-filled with only a single septa puncture in the field. Data indicate samples can be stored reliably for up to three days if punctured septa are coated in silicone sealant. To test whether this field sampling method was robust, we constructed a carbon-free sand column out of PVC pipe into which we plumbed a tank of known CO2 concentration and isotopic composition. We have tested the effects of wetting and flow rate on our ability to reproduce tank values. A linear model (geometric mean regression) yielded a more negative isotopic value than the actual gas, but a simple polynomial curve fit the tank value. After laboratory testing, the probes were established in a steep drainage in the H.J. Andrews LTER site in the Cascade Mountains of western Oregon (as part of the Andrews Airshed project). We established a transect of five 10 m2 plots with four soil probes and a companion respiration collar and measured soil CO2 efflux and soil δ13CO2 values biweekly from June-Sept. Results indicate there is a clear difference in isotopic and respiration flux patterns between the north- and south-facing slopes, with the north facing slope exhibiting higher fluxes and more 13C enriched respiration. The temporal pattern of respiration correlates well with decreasing soil moisture over the summer. In addition, flux and isotopic samples collected every 4 hours over a 24 hour period suggested strong diel patterns in both measures, with more enriched δ13C respired from soils in early morning and more δ13C depleted values during the day, suggesting that photosynthetic uptake and CO2 recycling by the aboveground vegetation influence soil-respired CO2 values.

Geological controls on soil parent material geochemistry along a northern Manitoba-North Dakota transect

USGS Publications Warehouse

Klassen, R.A.

2009-01-01

As a pilot study for mapping the geochemistry of North American soils, samples were collected along two continental transects extending east–west from Virginia to California, and north–south from northern Manitoba to the US–Mexican border and subjected to geochemical and mineralogical analyses. For the northern Manitoba–North Dakota segment of the north–south transect, X-ray diffraction analysis and bivariate relations indicate that geochemical properties of soil parent materials may be interpreted in terms of minerals derived from Shield and clastic sedimentary bedrock, and carbonate sedimentary bedrock terranes. The elements Cu, Zn, Ni, Cr and Ti occur primarily in silicate minerals decomposed by aqua regia, likely phyllosilicates, that preferentially concentrate in clay-sized fractions; Cr and Ti also occur in minerals decomposed only by stronger acid. Physical glacial processes affecting the distribution and concentration of carbonate minerals are significant controls on the variation of trace metal background concentrations.

Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys

USGS Publications Warehouse

Obbard, Martyn E.; Stapleton, Seth P.; Middel, Kevin R.; Thibault, Isabelle; Brodeur, Vincent; Jutras, Charles

2015-01-01

The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture–recapture studies indicate abundance was likely unchanged between 1986 and 2005, declines in body condition and survival occurred during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double-observer and distance sampling protocols. We surveyed small islands in James Bay and eastern Hudson Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark–recapture distance sampling and sight–resight models yielded an estimate of 860 (SE = 174) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (943; SE = 174) suggests that abundance is unlikely to have changed significantly since 1986. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture–recapture) and this survey. A conservative management approach is warranted given previous increases in duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012

USGS Publications Warehouse

Obbard, Martyn E.; Middel, Kevin R.; Stapleton, Seth P.; Thibault, Isabelle; Brodeur, Vincent; Jutras, Charles

2013-01-01

The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture-recapture studies indicate that abundance remained stable between 1986 and 2005, declines in body condition and survival were documented during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double observer and distance sampling protocols. We also surveyed small islands in Hudson Bay and James Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark-recapture distance sampling and sightresight models yielded a model-averaged estimate of 868 (SE: 177) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (951; SE: 177) suggests that abundance has remained unchanged. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture) and this survey. A conservative management approach is warranted given the previous increases in the duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

Community structures of actively growing bacteria shift along a north-south transect in the western North Pacific

PubMed Central

Taniguchi, Akito; Hamasaki, Koji

2008-01-01

Bacterial community structures and their activities in the ocean are tightly coupled with organic matter fluxes and thus control ocean biogeochemical cycles. Bromodeoxyuridine (BrdU), halogenated nucleoside and thymidine analogue, has been recently used to monitor actively growing bacteria (AGB) in natural environments. We labelled DNA of proliferating cells in seawater bacterial assemblages with BrdU and determined community structures of the bacteria that were possible key species in mediating biochemical reactions in the ocean. Surface seawater samples were collected along a north-south transect in the North Pacific in October 2003 and subjected to BrdU magnetic beads immunocapture and PCR-DGGE (BUMP-DGGE) analysis. Change of BrdU-incorporated community structures reflected the change of water masses along a north-south transect from subarctic to subtropical gyres in the North Pacific. We identified 25 bands referred to AGB as BrdU-incorporated phylotypes, belonging to Alphaproteobacteria (5 bands), Betaproteobacteria (1 band), Gammaproteobacteria (4 bands), Cytophaga-Flavobacterium-Bacteroides (CFB) group bacteria (5 bands), Gram-positive bacteria (6 bands), and Cyanobacteria (4 bands). BrdU-incorporated phylotypes belonging to Vibrionales, Alteromonadales and Gram-positive bacteria appeared only at sampling stations in a subtropical gyre, while those belonging to Roseobacter-related bacteria and CFB group bacteria appeared at the stations in both subarctic and subtropical gyres. Our result revealed phylogenetic affiliation of AGB and their dynamic change along with north-south environmental gradients in open oceans. Different species of AGB utilize different amount and kinds of substrates, which can affect the change of organic matter fluxes along transect. PMID:18177366

Visual search for tropical web spiders: the influence of plot length, sampling effort, and phase of the day on species richness.

PubMed

Pinto-Leite, C M; Rocha, P L B

2012-12-01

Empirical studies using visual search methods to investigate spider communities were conducted with different sampling protocols, including a variety of plot sizes, sampling efforts, and diurnal periods for sampling. We sampled 11 plots ranging in size from 5 by 10 m to 5 by 60 m. In each plot, we computed the total number of species detected every 10 min during 1 hr during the daytime and during the nighttime (0630 hours to 1100 hours, both a.m. and p.m.). We measured the influence of time effort on the measurement of species richness by comparing the curves produced by sample-based rarefaction and species richness estimation (first-order jackknife). We used a general linear model with repeated measures to assess whether the phase of the day during which sampling occurred and the differences in the plot lengths influenced the number of species observed and the number of species estimated. To measure the differences in species composition between the phases of the day, we used a multiresponse permutation procedure and a graphical representation based on nonmetric multidimensional scaling. After 50 min of sampling, we noted a decreased rate of species accumulation and a tendency of the estimated richness curves to reach an asymptote. We did not detect an effect of plot size on the number of species sampled. However, differences in observed species richness and species composition were found between phases of the day. Based on these results, we propose guidelines for visual search for tropical web spiders.

Characterizing the phylogenetic tree community structure of a protected tropical rain forest area in Cameroon.

PubMed

Manel, Stéphanie; Couvreur, Thomas L P; Munoz, François; Couteron, Pierre; Hardy, Olivier J; Sonké, Bonaventure

2014-01-01

Tropical rain forests, the richest terrestrial ecosystems in biodiversity on Earth are highly threatened by global changes. This paper aims to infer the mechanisms governing species tree assemblages by characterizing the phylogenetic structure of a tropical rain forest in a protected area of the Congo Basin, the Dja Faunal Reserve (Cameroon). We re-analyzed a dataset of 11538 individuals belonging to 372 taxa found along nine transects spanning five habitat types. We generated a dated phylogenetic tree including all sampled taxa to partition the phylogenetic diversity of the nine transects into alpha and beta components at the level of the transects and of the habitat types. The variation in phylogenetic composition among transects did not deviate from a random pattern at the scale of the Dja Faunal Reserve, probably due to a common history and weak environmental variation across the park. This lack of phylogenetic structure combined with an isolation-by-distance pattern of taxonomic diversity suggests that neutral dispersal limitation is a major driver of community assembly in the Dja. To assess any lack of sensitivity to the variation in habitat types, we restricted the analyses of transects to the terra firme primary forest and found results consistent with those of the whole dataset at the level of the transects. Additionally to previous analyses, we detected a weak but significant phylogenetic turnover among habitat types, suggesting that species sort in varying environments, even though it is not predominating on the overall phylogenetic structure. Finer analyses of clades indicated a signal of clustering for species from the Annonaceae family, while species from the Apocynaceae family indicated overdispersion. These results can contribute to the conservation of the park by improving our understanding of the processes dictating community assembly in these hyperdiverse but threatened regions of the world.

Determination of complex electromechanical coefficients for piezoelectric materials

NASA Astrophysics Data System (ADS)

Du, Xiao-Hong

Sugar maple decline, a result of many possible biotic and abiotic causes, has been a problem in northern Pennsylvania since the early 1980s. Several studies have focused on specific causes, yet few have tried to look at a wide array. The purpose of this research was to investigate stresses in sugar maple forest plots in northern Pennsylvania. Three studies were undertaken. The first study examined the spatial extent of sugar maple on 248 plots in Bailey's ecoregions 212F and 212G, which are glaciated and unglaciated regions, respectively. In addition, a health assessment of sugar maple in Pennsylvania was made, with a resulting separation in population between healthy and unhealthy stands occurring at 20 percent dead sugar maple basal area. The second study was conducted to evaluate a statistical sampling design of 28 forested plots, from the above studies population of plots (248), and to provide data on physical and chemical soil variability and sample size estimation for other researchers. The variability of several soil parameters was examined within plots and between health classes of sugar maple and sample size estimations were derived for these populations. The effect of log-normal transformations on reducing variability and sample sizes was examined and soil descriptions of the plots sampled in 1998 were compared to the USDA Soil Survey mapping unit series descriptions for the plot location. Lastly, the effect of sampling intensity on the detection of significant differences between health class treatments was examined. The last study addressed sugar maple decline in northern Pennsylvania during the same period as the first study (approximately 1979-1989) but on 28 plots chosen from the first studies population. These were the same plots used in the second study on soil variability. Recent literature on sugar maple decline has focused on specific causes and few have tried to look at a wide array. This paper investigates stresses in sugar maple plots related to moisture and how these interact with other stresses such as chemistry, insect defoliation, geology, aspect, slope, topography, and atmospheric deposition.

Multifractal analyis of soil invertebrates along a transect under different land uses

NASA Astrophysics Data System (ADS)

Machado Siqueira, Glécio; Alves Silva, Raimunda; Vidal-Vázquez, Eva; Paz-González, Antonio

2017-04-01

Soil fauna play a central role in many essential ecosystem processes. Land use and management can have a dramatic effect upon soil invertebrate community. Indices based on soil invertebrates abundance and diversity are fundamental for soil quality assessment. Many soil properties and attributes have been shown to exhibit spatial variabilityThe aim of this study was to analyze the scaling heterogeneity of the soil invertebrate community sampled using pitfall traps across a transect. The field study was conducted at Mata Roma municipality, Maranhão State, Brazil. Transects were marked under seven different agricultural/forestry land uses (millet, soybean, maize, eucalyptus, pasture, secondary savannah and native savannah). Native vegetation was considered as a reference, whereas the agricultural fields showed a range of soil use intensities. Along these transects 130 pitfall per land use were installed. First, differences in community assemblages and composition under different land use systems were evaluated using classical indices. Then, the spatial distribution of soil fauna trapped by pitfall techniques, characterized through generalized dimension, Dq, and singularity spectra, f(α) - α, showed a well-defined multifractal structure. Differences in scaling heterogeneity and other multifractal characteristics were examined in relation to land use intensification.

Four soil orders on a Vermont mountaintop-one-third of the world`s soil orders in a 2500-square-meter research plot

Treesearch

Thomas R. Villars; Scott W. Bailey; Donald S. Ross

2015-01-01

As part of the Vermont Long-Term Soil Monitoring Project, five 50 x 50 m plots were established on protected forestland across Vermont. In 2002, ten randomly selected subplots at each monitoring plot were sampled. The 10 pedons sampled at the high-elevation spruce-fir “Forehead” plot on Mount Mansfield were found to include soils of four taxonomic Orders: Entisols,...

Where are the Black Walnut Trees in Michigan? 1995

Treesearch

J. Michael Vasievich; Neal P. Kingsley

1995-01-01

The latest Michigan forest inventory was completed in 1993 by the North Central Forest Experiment Station and the Michigan DNR, Forest Management Division. In total, 18,484 sample points were examined on aerial photographs to identify ground sample plots. Of these, 10,849 forest plots were visited and measured on the ground by field crews. These plot measurements...

Modeling the uncertainty of estimating forest carbon stocks in China

NASA Astrophysics Data System (ADS)

Yue, T. X.; Wang, Y. F.; Du, Z. P.; Zhao, M. W.; Zhang, L. L.; Zhao, N.; Lu, M.; Larocque, G. R.; Wilson, J. P.

2015-12-01

Earth surface systems are controlled by a combination of global and local factors, which cannot be understood without accounting for both the local and global components. The system dynamics cannot be recovered from the global or local controls alone. Ground forest inventory is able to accurately estimate forest carbon stocks at sample plots, but these sample plots are too sparse to support the spatial simulation of carbon stocks with required accuracy. Satellite observation is an important source of global information for the simulation of carbon stocks. Satellite remote-sensing can supply spatially continuous information about the surface of forest carbon stocks, which is impossible from ground-based investigations, but their description has considerable uncertainty. In this paper, we validated the Lund-Potsdam-Jena dynamic global vegetation model (LPJ), the Kriging method for spatial interpolation of ground sample plots and a satellite-observation-based approach as well as an approach for fusing the ground sample plots with satellite observations and an assimilation method for incorporating the ground sample plots into LPJ. The validation results indicated that both the data fusion and data assimilation approaches reduced the uncertainty of estimating carbon stocks. The data fusion had the lowest uncertainty by using an existing method for high accuracy surface modeling to fuse the ground sample plots with the satellite observations (HASM-SOA). The estimates produced with HASM-SOA were 26.1 and 28.4 % more accurate than the satellite-based approach and spatial interpolation of the sample plots, respectively. Forest carbon stocks of 7.08 Pg were estimated for China during the period from 2004 to 2008, an increase of 2.24 Pg from 1984 to 2008, using the preferred HASM-SOA method.

Escherichia coli sampling reliability at a frequently closed Chicago beach: monitoring and management implications

USGS Publications Warehouse

Whitman, Richard L.; Nevers, Meredith B.

2004-01-01

Monitoring beaches for recreational water quality is becoming more common, but few sampling designs or policy approaches have evaluated the efficacy of monitoring programs. The authors intensively sampled water for E. coli (N=1770) at 63rd Street Beach, Chicago for 6 months in 2000 in order to (1) characterize spatial-temporal trends, (2) determine between and within transect variation, and (3) estimate sample size requirements and determine sampling reliability.E. coli counts were highly variable within and between sampling sites but spatially and diurnally autocorrelated. Variation in counts decreased with water depth and time of day. Required number of samples was high for 70% precision around the critical closure level (i.e., 6 within or 24 between transect replicates). Since spatial replication may be cost prohibitive, composite sampling is an alternative once sources of error have been well defined. The results suggest that beach monitoring programs may be requiring too few samples to fulfill management objectives desired. As the recreational water quality national database is developed, it is important that sampling strategies are empirically derived from a thorough understanding of the sources of variation and the reliability of collected data. Greater monitoring efficacy will yield better policy decisions, risk assessments, programmatic goals, and future usefulness of the information.

Effects of Spontaneous Colonization by Eriophorum vaginatum on Belowground C and N Mobilization and Greenhouse Gas Emissions in a Restored Boreal Peatland

NASA Astrophysics Data System (ADS)

Lazcano, C.; Brummell, M.; Strack, M.

2016-12-01

Peatland restoration aims at recovering the ecological function of these ecosystems as active C sinks by re-establishing Sphagnum-dominated vegetation. In addition, restoration encourages the establishment of naturally occurring vascular plant species from the local seed bank. Whereas these plants could contribute to a substantial short-term increase in C sequestration due to their large biomass accumulation, their impacts on peat biogeochemistry are complex and belowground C and N mobilization could be substantial, leading to increased greenhouse gas emissions. We investigated the effects of cottongrass (Eriophorum vaginatum), a common vascular plant species colonizing extracted peatlands, on porewater dissolved organic C (DOC) and total dissolved N (TDN) as well as CO2, CH4 and N2O fluxes in a cutover boreal bog in Alberta (Canada), restored three years prior to the study. We hypothesized that cottongrass would increase the concentration of DOC and TDN in porewater as well as net N2O and CH4 emission from peat compared to areas of bare peat or moss. We studied porewater chemistry and net gas exchange for CO2, CH4, and N2O, using static chambers, over one growing season (May-September 2015) and we compared between plots containing cottongrass and plots lacking vascular plants. Plots were located along a transect of increasing water table, to discriminate between the effects of cottongrass and the prevailing hydrological conditions on porewater chemistry and gas fluxes. Cottongrass presence had contrasting effects on porewater DOC chemistry depending on wetness of the site, reducing DOC concentration in dry sites but increasing it at wet sites as compared with bare plots. This suggests that DOC mobilization is primarily controlled by hydrological conditions rather than cottongrass presence. However, cottongrass significantly increased CH4 emissions independently of the plot moisture. Cottongrass presence reduced net emission of N2O in the later part of the growing season, with cottongrass plots frequently acting as net consumers in July and August. Porewater TDN was significantly higher under cottongrass at the wettest area of the site than under either bare or cottongrass plots at the drier area, suggesting nitrogen mobilization from peat by an interaction between cottongrass roots and water.

How To ... Guide

Treesearch

Duncan C. Lutes; Robert E. Keane; John F. Caratti; Carl H. Key; Nathan C. Benson

2006-01-01

This is probably the most critical phase of FIREMON sampling because this plot ID must be unique across all plots that will be entered in the FIREMON database. The plot identifier is made up of three parts: Registration Code, Project Code, and Plot Number.The FIREMON Analysis Tools program will allow summarization and comparison of plots only if...

Factors Influencing Uptake of Sylvatic Plague Vaccine Baits by Prairie Dogs.

PubMed

Abbott, Rachel C; Russell, Robin E; Richgels, Katherine L D; Tripp, Daniel W; Matchett, Marc R; Biggins, Dean E; Rocke, Tonie E

2017-11-20

Sylvatic plague vaccine (SPV) is a virally vectored bait-delivered vaccine expressing Yersinia pestis antigens that can protect prairie dogs (Cynomys spp.) from plague and has potential utility as a management tool. In a large-scale 3-year field trial, SPV-laden baits containing the biomarker rhodamine B (used to determine bait consumption) were distributed annually at a rate of approximately 100-125 baits/hectare along transects at 58 plots encompassing the geographic ranges of four species of prairie dogs. We assessed site- and individual-level factors related to bait uptake in prairie dogs to determine which were associated with bait uptake rates. Overall bait uptake for 7820 prairie dogs sampled was 70% (95% C.I. 69.9-72.0). Factors influencing bait uptake rates by prairie dogs varied by species, however, in general, heavier animals had greater bait uptake rates. Vegetation quality and day of baiting influenced this relationship for black-tailed, Gunnison's, and Utah prairie dogs. For these species, baiting later in the season, when normalized difference vegetation indices (a measure of green vegetation density) are lower, improves bait uptake by smaller animals. Consideration of these factors can aid in the development of species-specific SPV baiting strategies that maximize bait uptake and subsequent immunization of prairie dogs against plague.

Factors influencing uptake of sylvatic plague vaccine baits by prairie dogs

USGS Publications Warehouse

Abbott, Rachel C.; Russell, Robin E.; Richgels, Katherine; Tripp, Daniel W.; Matchett, Marc R.; Biggins, Dean E.; Rocke, Tonie E.

2017-01-01

Sylvatic plague vaccine (SPV) is a virally vectored bait-delivered vaccine expressing Yersinia pestis antigens that can protect prairie dogs (Cynomys spp.) from plague and has potential utility as a management tool. In a large-scale 3-year field trial, SPV-laden baits containing the biomarker rhodamine B (used to determine bait consumption) were distributed annually at a rate of approximately 100–125 baits/hectare along transects at 58 plots encompassing the geographic ranges of four species of prairie dogs. We assessed site- and individual-level factors related to bait uptake in prairie dogs to determine which were associated with bait uptake rates. Overall bait uptake for 7820 prairie dogs sampled was 70% (95% C.I. 69.9–72.0). Factors influencing bait uptake rates by prairie dogs varied by species, however, in general, heavier animals had greater bait uptake rates. Vegetation quality and day of baiting influenced this relationship for black-tailed, Gunnison’s, and Utah prairie dogs. For these species, baiting later in the season, when normalized difference vegetation indices (a measure of green vegetation density) are lower, improves bait uptake by smaller animals. Consideration of these factors can aid in the development of species-specific SPV baiting strategies that maximize bait uptake and subsequent immunization of prairie dogs against plague.

Macrophyte species distribution, indices of biotic integrity and sampling intensity in isolated Florida marshes

EPA Science Inventory

This study tested macrophyte condition metrics calculated after decreasing the effort and area of sampling by 33% to 66%, as tested in 74 emergent isolated wetlands. Four belted transects from wetland edge to center were established and rooted macrophytes were identified. The eff...

User’s guide to the North Pacific Pelagic Seabird Database 2.0

USGS Publications Warehouse

Drew, Gary S.; Piatt, John F.; Renner, Martin

2015-07-13

The North Pacific Pelagic Seabird Database (NPPSD) was created in 2005 to consolidate data on the oceanic distribution of marine bird species in the North Pacific. Most of these data were collected on surveys by counting species within defined areas and at known locations (that is, on strip transects). The NPPSD also contains observations of other bird species and marine mammals. The original NPPSD combined data from 465 surveys conducted between 1973 and 2002, primarily in waters adjacent to Alaska. These surveys included 61,195 sample transects with location, environment, and metadata information, and the data were organized in a flat-file format. In developing NPPSD 2.0, our goals were to add new datasets, to make significant improvements to database functionality and to provide the database online. NPPSD 2.0 includes data from a broader geographic range within the North Pacific, including new observations made offshore of the Russian Federation, Japan, Korea, British Columbia (Canada), Oregon, and California. These data were imported into a relational database, proofed, and structured in a common format. NPPSD 2.0 contains 351,674 samples (transects) collected between 1973 and 2012, representing a total sampled area of 270,259 square kilometers, and extends the time series of samples in some areas—notably the Bering Sea—to four decades. It contains observations of 16,988,138 birds and 235,545 marine mammals and is available on the NPPSD Web site. Supplementary materials include an updated set of standardized taxonomic codes, reference maps that show the spatial and temporal distribution of the survey efforts and a downloadable query tool.

Dynamics of vegetation and soils of oak/saw palmetto scrub after fire: Observations from permanent transects

NASA Technical Reports Server (NTRS)

Schmalzer, Paul A.; Hinkle, G. Ross

1991-01-01

Ten permanent 15 m transects previously established in two oak/saw palmetto scrub stands burned in December 1986, while two transects remained unburned. Vegetation in the greater than 0.5 m and the less than 0.5 m layers on these transects was sampled at 6, 12, 18, 24, and 36 months postburn and determined structural features of the vegetation (height, percent bare ground, total cover). The vegetation data were analyzed from each sampling by height layer using detrended correspondence analysis ordination. Vegetation data for the greater than 0.5 m layer for the entire time sequence were combined and analyzed using detrended correspondence analysis ordination. Soils were sampled at 6, 12, 18, and 24 months postburn and analyzed for pH, conductivity, organic matter, exchangeable cations (Ca, Mg, K, Na), NO3-N, NH4-N, Al, available metals (Cu, Fe, Mn, Zn), and PO4-P. Shrub species recovered at different rates postfire with saw palmetto reestablishing cover greater than 0.5 m within one year, but the scrub oaks had not returned to preburn cover greater than 0.5 m in 3 years after the fire. These differences in growth rates resulted in dominance shifts after the fire with saw palmetto increasing relative to the scrub oaks. Overall changes in species richness were minor, although changes occurred in species richness by height layers due to different growth rates. Soils of well drained and poorly drained sites differed markedly. Soil responses to the fire appeared minor. Soil pH increased at 6 and 12 months postfire; calcium increased at 6 months postburn. Nitrate-nitrogen increased at 12 months postburn. Low values of conductivity, PO4-P, Mg, K, Na, and Fe at 12 months postburn may be related to heavy rainfall the preceding month. Seasonal variability in some soil parameters appeared to occur.

Geochemistry of soils along a transect from Central Mexico to the Pacific Coast: a pilot study for continental-scale geochemical mapping

USGS Publications Warehouse

Chiprés, J.A.; de la Calleja,; Tellez, J.I.; Jiménez, F.; Cruz, Carlos; Guerrero, E.G.; Castro, J.; Monroy, M.G.; Salinas, J.C.

2009-01-01

The Mexican Geological Survey (SGM), the National Institute of Statistics, Geography and Informatics (INEGI) and the Autonomous University of San Luis Potosi (UASLP) have established a multidisciplinary team with the objective of creating a national program of geochemical mapping of soils in Mexico. This is being done as part of the North American Soil Geochemical Landscapes Project in partnership with the US Geological Survey and the Geological Survey of Canada. As the first step, a pilot study was conducted over a transect that extends from the Mexico–US border near Ciudad Juarez in the north to the Pacific Ocean in the south. This pilot transect was conducted in two phases, and this paper presents results from the first phase, which sampled soils at about a 40-km spacing along a 730-km transect beginning in Central Mexico and ending at the Pacific Coast. Samples were collected from the A and C horizons at each site and 60 elements were analyzed. This pilot study demonstrates that geochemical mapping based on a 40-km spacing is adequate to identify broad-scale geochemical patterns. Geologic influence (i.e., soil parent material) was the most important factor influencing the distribution of elements along the transect, followed by the influence of regional mineralization. The study also showed that influence by human activities over the transect is minimal except possibly in large mining districts. A comparison of element abundance in the A horizon with the environmental soil guidelines in Mexico showed that the natural concentrations of the studied soils were lower than the established threshold for soil restoration with the exception of V and As. The former had a median value (75 mg/kg) approximately equal to the value established in Mexico for soil restoration in agricultural and residential lands (78 mg/kg), and the latter had three values higher than the 22 mg/kg threshold for soil restoration in agricultural and residential lands. These cases demonstrate the importance of knowing the national- and regional-scale geochemistry of Mexican soils as a support for the decision-making process, particularly for the proper formulation and application of soil guidelines designed to protect human and ecosystem health.

SPRUCE Shrub-Layer Growth Assessments in S1-Bog Plots and SPRUCE Experimental Plots beginning in 2010

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

Hanson, P.J.; Phillips, J.R.; Brice, D.J.

This data set reports shrub layer growth assessments for the S1-Bog on the Marcell Experimental Forest in Minnesota from 2010 through 2017. Data were obtained by destructively harvesting two 0.25 m2 plots within defined plot areas of the S1-Bog or SPRUCE experimental plots. In 2015, SPRUCE plots 4, 6, 8, 10, 11, 13, 16, 17, 19 and 20 were enclosed in the SPRUCE enclosures. Prior to 2015 all data are for open ambient conditions. In early years a distinct hummock and a hollow sampling square were both collected, but in later years unsampled hollow areas became unavailable due to priormore » sampling or instrument installations. All vegetation material above the Sphagnum surface of the bog was clipped and transferred to plastic storage bags which were then frozen until the samples could be sorted. Sorting was done by species, tissue type (leaves vs. stems) and tissue age (current-year vs. older tissues).« less

Early changes in muscle atrophy and muscle fiber type conversion after spinal cord transection and peripheral nerve transection in rats.

PubMed

Higashino, Kosaku; Matsuura, Tetsuya; Suganuma, Katsuyoshi; Yukata, Kiminori; Nishisho, Toshihiko; Yasui, Natsuo

2013-05-20

Spinal cord transection and peripheral nerve transection cause muscle atrophy and muscle fiber type conversion. It is still unknown how spinal cord transection and peripheral nerve transection each affect the differentiation of muscle fiber type conversion mechanism and muscle atrophy. The aim of our study was to evaluate the difference of muscle weight change, muscle fiber type conversion, and Peroxisome proliferator-activated receptor-γ coactivatior-1α (PGC-1α) expression brought about by spinal cord transection and by peripheral nerve transection. Twenty-four Wistar rats underwent surgery, the control rats underwent a laminectomy; the spinal cord injury group underwent a spinal cord transection; the denervation group underwent a sciatic nerve transection. The rats were harvested of the soleus muscle and the TA muscle at 0 week, 1 week and 2 weeks after surgery. Histological examination was assessed using hematoxylin and eosin (H&E) staining and immunofluorescent staing. Western blot was performed with 3 groups. Both sciatic nerve transection and spinal cord transection caused muscle atrophy with the effect being more severe after sciatic nerve transection. Spinal cord transection caused a reduction in the expression of both sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection produced an increase in expression of sMHC protein and PGC-1α protein in the soleus muscle. The results of the expression of PGC-1α were expected in other words muscle atrophy after sciatic nerve transection is less than after spinal cord transection, however muscle atrophy after sciatic nerve transection was more severe than after spinal cord transection. In the conclusion, spinal cord transection diminished the expression of sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection enhanced the expression of sMHC protein and PGC-1α protein in the soleus muscle.

Partitioning and transport of total and methyl mercury in the Lower Fox River, Wisconsin

USGS Publications Warehouse

Hurley, J.P.; Cowell, S.E.; Shafer, M.M.; Hughes, P.E.

1998-01-01

To investigate transport and partitioning processes of Hg(T) in the Fox River, we coupled detailed time series data of total mercury (Hg(T)) at the river mouth with transect sampling in the Lower Fox River. Unfiltered Hg(T) concentrations in the Fox River during the study period (April 1994-October 1995) ranged from 1.8 to 182 ng L(-1) with a median of 24.8 ng L-1, predominantly (93.6%) in the particulate phase. These levels were significantly elevated compared with other large tributaries to Lake Michigan (Hurley, J. P.; Shafer, M. M.; Cowell, S. E.; Overdier, J. T.; Hughes, P. E.; Armstrong, D. E. Environ. Sci. Technol. 1996, 30, 20932098). Transect sampling revealed progressively increasing water column Hg(T) concentrations and Hg(T) particulate enrichment downstream, which were consistent with trends in sediment Hg(T) levels in the river. Resuspended sediments are likely the predominant source of Hg from the Fox River into Green Bay. Despite elevated Hg(T) concentrations, methyl mercury (MeHg) concentrations were relatively low, suggesting limited bioavailability of Hg(T) associated with sediments.To investigate transport and partitioning processes of HgT in the Fox River, we coupled detailed time series data of total mercury (HgT) at the river mouth with transect sampling in the Lower Fox River. Unfiltered HgT concentrations in the Fox River during the study period (April 1994-October 1995) ranged from 1.8 to 182 ng L-1 with a median of 24.8 ng L-1, predominantly (93.6%) in the particulate phase. These levels were significantly elevated compared with other large tributaries to Lake Michigan. Transect sampling revealed progressively increasing water column HgT concentrations and HgT particulate enrichment downstream, which were consistent with trends in sediment HgT levels in the river. Resuspended sediments are likely the predominant source of Hg from the Fox River into Green Bay. Despite elevated HgT concentrations, methyl mercury (MeHg) concentrations were relatively low, suggesting limited bioavailability of HgT associated with sediments.

Recreational water quality response to a filtering barrier at a Great Lakes beach

USGS Publications Warehouse

Przybyla-Kelly, Kasia; Nevers, Meredith; Breitenbach, Cathy; Whitman, Richard L.

2013-01-01

Recent research has sought to determine the off- or onshore origin of fecal indicator bacteria (FIB) in order to improve local recreational water quality. In an effort to reduce offshore contamination, a filtering barrier (FB) was installed at Calumet Beach, Lake Michigan, Chicago, IL. A horseshoe-shaped curtain (146 m long, 0.18 mm apparent opening size, 1.5–1.6 m deepest point) was designed to exclude FIB containing or promoting debris and thus reduce the number of swimming advisories during the examination period of July through September 2012. Mean water Escherichia coli concentrations were significantly lower at southern transects (S; outside FB) than at transects within the FB (WN) and at northern transects (N; outside FB) (1.45 log (MPN)/100 ml vs. 1.74 and 1.72, respectively, p < 0.05, n = 234). Turbidity was significantly higher at the WN transects (p < 0.001, n = 233), but it tended to increase throughout the sampling season within and outside the FB. E. coli in adjacent foreshore sand was significantly lower at the WN transects. A combination of factors might explain higher E. coli and turbidity within the FB including increased sediment resuspension, trapped algae, shallowing within the FB, and large lake hydrodynamic processes. This remediation approach may find better use in a different hydrodynamic setting, but the results of this experiment provide insight on sources of contamination and nearshore dynamics that may direct future beach management strategies.

Isotope and fatty acid trends along continental shelf depth gradients: Inshore versus offshore hydrological influences on benthic trophic functioning

NASA Astrophysics Data System (ADS)

Chouvelon, T.; Schaal, G.; Grall, J.; Pernet, F.; Perdriau, M.; A-Pernet, E. J.; Le Bris, H.

2015-11-01

Anthropogenic activities and land-based inputs into the sea may influence the trophic structure and functioning of coastal and continental shelf ecosystems, despite the numerous opportunities and services the latter offer to humans and wildlife. In addition, hydrological structures and physical dynamics potentially influence the sources of organic matter (e.g., terrestrial versus marine, or fresh material versus detrital material) entering marine food webs. Understanding the significance of the processes that influence marine food webs and ecosystems (e.g., terrestrial inputs, physical dynamics) is crucially important because trophic dynamics are a vital part of ecosystem integrity. This can be achieved by identifying organic matter sources that enter food webs along inshore-offshore transects. We hypothesised that regional hydrological structures over wide continental shelves directly control the benthic trophic functioning across the shelf. We investigated this issue along two transects in the northern ecosystem of the Bay of Biscay (north-eastern Atlantic). Carbon and nitrogen stable isotope analysis (SIA) and fatty acid analysis (FAA) were conducted on different complementary ecosystem compartments that include suspended particulate organic matter (POM), sedimentary organic matter (SOM), and benthic consumers such as bivalves, large crustaceans and demersal fish. Samples were collected from inshore shallow waters (at ∼1 m in depth) to more than 200 m in depth on the offshore shelf break. Results indicated strong discrepancies in stable isotope (SI) and fatty acid (FA) compositions in the sampled compartments between inshore and offshore areas, although nitrogen SI (δ15N) and FA trends were similar along both transects. Offshore the influence of a permanently stratified area (described previously as a ;cold pool;) was evident in both transects. The influence of this hydrological structure on benthic trophic functioning (i.e., on the food sources available for consumers) was especially apparent across the northern transect, due to unusual carbon isotope compositions (δ13C) in the compartments. At stations under the cold pool, SI and FA organism compositions indicated benthic trophic functioning based on a microbial food web, including a significant contribution of heterotrophic planktonic organisms and/or of SOM, notably in stations under the cold pool. On the contrary, inshore and shelf break areas were characterised by a microalgae-based food web (at least in part for the shelf break area, due to slope current and upwelling that can favour fresh primary production sinking on site). SIA and FAA were relevant and complementary tools, and consumers better medium- to long-term system integrators than POM samples, for depicting the trophic functioning and dynamics along inshore-offshore transects over continental shelves.

Procedures for establishing and maintaining permanent plots for silvicultural and yield research.

Treesearch

Robert O. Curtis

1983-01-01

This paper reviews procedures for establishing and maintaining permanent plots for silvicultural and yield research; discusses purposes, sampling, and plot design; points out common errors; and makes recommendations for research plot designs and procedures for measuring and recording data.

Evaluation of a Proposed Modified F/FB-111 Crew Seat and Restraint System.

DTIC Science & Technology

1981-11-01

each target’s path in the X-Z plane throughout the impact. (See sample plots.) Computing velocities and accelerations was a simple matter in the...until this work unit is retired. The experimental results will eventually be recorded within a permanent data bank at AFAMRL. The sample data plots were... experimental results will eventually be recorded within a permanent data bank at AFAMRL. The sample data plots were selected based on the subject who had the

Spatial variation in below ground carbon cycling in a pristine peatland, driven by present and past vegetation

NASA Astrophysics Data System (ADS)

Mathijssen, Paul; Knorr, Klaus-Holger; Gałka, Mariusz; Borken, Werner

2017-04-01

Peat carbon cycling is controlled by both large scale factors, such as climate and hydrological setting, and small scale factors, such as microtopography, vegetation, litter quality, and rooting depth. These small scale factors commonly vary within peatlands, causing variation in the carbon balance at different locations within the same site. Understanding the relationship between small scale carbon cycling and vegetation helps us to assess the variation of carbon dynamics of peatlands, because vegetation composition acts as an integrator of factors such as microtopography, hydrology, and nutrient level. Variation in vegetation illustrates spatial variation of these underlying factors. Furthermore, the presence of certain plant species affects carbon cycling directly through litter quality or aeration through root tissues. In order to understand these within-site variations in terms of carbon cycling, we investigated carbon accumulation, decomposition, and biogeochemistry of pore waters along a transect of peat cores with changing vegetation and water levels in an ombrotrophic peatland in southern Patagonia. The transect ran from a Sphagnum magellanicum dominated spot with relatively high water table, to intermediately wet spots with mixed Sphagnum/shrubs vegetation, or dominated by Cyperaceae, eventually to a more elevated and drier spot dominated by cushion plants (mainly Astelia pumila). There were large differences in peat accumulation rates and peat densities, with faster peat growth and lower densities under Sphagnum, but overall carbon accumulation rates were quite similar in the various microenvironments. At most plots C/N ratios decreased with depth, concurrent with increasing humification index derived from FT-IR spectra. But under cushion plants this relation was opposite: more humification with depth, but also C/N ratios increases. This reflected the differing source material at depth under the cushion plants, and that the cushion plant peat layers were formed on top of Sphagnum peat. The divergent source material throughout a peat core makes it difficult to use C/N ratios to indicate peat decomposition rates. Although the low peat density and higher C/N ratios indicate that overall carbon turnover is slow at Sphagnum plots, pore water methane concentrations were elevated. At cushion plant plots, however, higher redox potentials exist until greater depths due to aerenchymous roots, inhibiting methane production and release. Our results demonstrate that large variation exists within pristine bogs, in terms of decomposition patterns, organic matter quality, and carbon turnover pathways, corresponding to variation in surface moisture levels and vegetation. Furthermore, variation in carbon cycling properties are maintained in buried peat layers and reflect more the organic material of that layer, than the current surface carbon dynamics.

Human exposure to soil contaminants in subarctic Ontario, Canada.

PubMed

Reyes, Ellen Stephanie; Liberda, Eric Nicholas; Tsuji, Leonard James S

2015-01-01

Chemical contaminants in the Canadian subarctic present a health risk with exposures primarily occurring via the food consumption. Characterization of soil contaminants is needed in northern Canada due to increased gardening and agricultural food security initiatives and the presence of known point sources of pollution. A field study was conducted in the western James Bay Region of Ontario, Canada, to examine the concentrations of polychlorinated biphenyls, dichlorodiphenyltrichloroethane and its metabolites (ΣDDT), other organochlorines, and metals/metalloids in potentially contaminated agriculture sites. Exposure pathways were assessed by comparing the estimated daily intake to acceptable daily intake values. Ninety soil samples were collected at random (grid sampling) from 3 plots (A, B, and C) in Fort Albany (on the mainland), subarctic Ontario, Canada. The contaminated-soil samples were analysed by gas chromatography with an electron capture detector or inductively coupled plasma mass spectrometer. The range of ΣDDT in 90 soil samples was below the limit of detection to 4.19 mg/kg. From the 3 soil plots analysed, Plot A had the highest ΣDDT mean concentration of 1.12 mg/kg, followed by Plot B and Plot C which had 0.09 and 0.01 mg/kg, respectively. Concentrations of other organic contaminants and metals in the soil samples were below the limit of detection or found in low concentrations in all plots and did not present a human health risk. Exposure analyses showed that the human risk was below regulatory thresholds. However, the ΣDDT concentration in Plot A exceeded soil guidelines set out by the Canadian Council of Ministers of the Environment of 0.7 mg/kg, and thus the land should not be used for agricultural or recreational purposes. Both Plots B and C were below threshold limits, and this land can be used for agricultural purposes.

On estimation in k-tree sampling

Treesearch

Christoph Kleinn; Frantisek Vilcko

2007-01-01

The plot design known as k-tree sampling involves taking the k nearest trees from a selected sample point as sample trees. While this plot design is very practical and easily applied in the field for moderate values of k, unbiased estimation remains a problem. In this article, we give a brief introduction to the...

Measurements and Interpretation of Surface Mixing Ratios of CH4 and CO and δ 13C and δ D of CH4 in Air from Pacific Ocean Transects Between Auckland, New Zealand and Los Angeles, California

NASA Astrophysics Data System (ADS)

Ajie, H. O.; Tyler, S. C.; Gotoh, A. A.; McMillan, A. M.; Rice, A. L.; Lowe, D. C.

2003-12-01

We report on measurements of atmospheric CH4 and CO mixing ratios and δ 13C of CH4 from air samples collected every 2.5 to 5° latitude along a transect over the Pacific Ocean using container ships of P&O Nedlloyd (formerly Blue Star) shipping line. Data presented here begins in June 1996 and extends to January 2002. Scientists from the National Institute of Water and Atmospheric Research in New Zealand and from University of California, Irvine alternate sampling trips so that a transect between Auckland, New Zealand (35° S) and Los Angeles, California (35° N) can be sampled over a period of ˜15 days approximately every four months. Data sets from the two laboratories are intercalibrated through a sample exchange program. The data provide detail on the spatial and seasonal variation of CH4 and CO mixing ratios and stable isotope ratios of CH4 over the Pacific equatorial region, including the Intertropical Convergence Zone (ITCZ) and both northern and southern temperate zones to about 30° latitude, including the South Pacific Convergence Zone (SPCZ). Data from 18 transect samplings so far clearly show that δ 13C in the mid latitudes of both hemispheres are ˜6 months out of phase. In June, a minimum in δ 13C CH4 in the southern hemisphere (SH) coincides approximately with the maximum in the northern hemisphere (NH) seasonal cycle. Because the NH is less enriched in 13C than the SH this situation results in a remarkably flat gradient between 30° N and 30° S. In November the opposite situation occurs with the SH mid latitude maximum coinciding with the minimum in the NH cycle, leading to a relatively large gradient of ˜0.5‰ between the hemispheres. We discuss how CH4 and CO mixing ratios are related to the changing positions and strengths of the ITCZ and SPCZ and how this data can be used in multi-dimensional models of atmospheric chemistry and transport to better define CH4 sources and sinks both temporally and spatially.

Redox speciation of dissolved iron in the northeastern atlantic ocean.

NASA Astrophysics Data System (ADS)

Ussher, S. J.; Achterberg, E. P.; Worsfold, P. J.

2003-04-01

Dissolved iron (<0.2 micron) and iron(II) (<0.2 micron) distributions were determined during the Iron from Below and Iron from Above research cruises in the North Eastern Atlantic Ocean. The cruises were part of the EU Ironages project. Iron(II) was measured on-board ship using an iron(II) specific, automated flow injection analyser with luminol chemiluminescence detection [1]. Total dissolved iron (DFe) was determined in a land-based laboratory, using the same FI technique but with prior reduction of iron(III) to iron(II) [2]. The limits of detection for the methods were 5 -15 pM and 35 pM respectively, the analysis time was 8 - 10 minutes per sample (minimum of 3 replicates). The Iron from Below expedition took place over the European Continental Shelf, 200 km South West of Brittany (France) in March 2002. A transect between 47.61°N, 4.24°W and 46.00°N, 8.01°W was completed. Over the transect, the depth increased from 100 m to 5000 m. Iron(II) concentrations ranged between 10 and 100 pM and DFe between 0.2 and 1 nM, with the higher concentrations (Fe(II) ca. > 50 pM and DFe ca. > 0.8 nM) generally found in the shallow shelf waters. These observations imply that benthic inputs and sediment resuspension may form important inputs of dissolved iron and iron(II) in the shelf waters. Iron speciation measurements were also made for underway surface and shallow cast samples during the Iron from Above cruise October 2002. Fe(II) and DFe concentrations were typically 5 to 50 pM and 0.2 to 0.6 nM, respectively. Sampling was carried out within a grid in the Canary Basin around 5 degrees W of the Canary Islands, an area assumed to be strongly influenced by the Saharan dust plume. Observed Fe(II) concentrations are compared and ratioed to the DFe concentrations, and indicate that iron(II) forms an important fraction (between 5 and 15%) of the total dissolved iron concentration in the study areas. Data plots for surface samples are presented with the corresponding physical oceanographic and solar irradiance data. The concentrations of Fe(II) observed during our studies exceed the values predicted from thermodynamic equilibrium modelling. This indicates that there is a steady supply of Fe(II) (possibly from photoreduction and/or biological origins) and/or Fe(II) is prevented from oxidation through stabilisation mechanisms (possibly by organic ligands). [1] A. R. Bowie, E. P. Achterberg, P. N. Sedwick, S. Ussher, P. J. Worsfold, Environ. Sci. Technol., 36, (2002) 4600. [2] A. R. Bowie, E. P. Achterberg, R. F. C. Mantoura, P. J. Worsfold, Anal. Chim. Acta, 377, (1998) 113.

Monitoring biological impacts of space shuttle launches from Vandenberg Air Force Base: Establishment of baseline conditions

NASA Technical Reports Server (NTRS)

Schmaizer, Paul A.; Hinkle, C. Ross

1987-01-01

Space shuttle launches produce environmental impacts resulting from the formation of an exhaust cloud containing hydrogen chloride aerosols and aluminum oxide particulates. Studies have shown that most impacts occur near-field (within 1.5 km) of the launch site while deposition from launches occurs far-field (as distant as 22 km). In order to establish baseline conditions of vegetation and soils in the areas likely to be impacted by shuttle launches from Vandenberg Air Force Base (VAFB), vegetation and soils in the vicinity of Space Launch Complex-6 (SLC-6) were sampled and a vegetation map prepared. The areas likely to be impacted by launches were determined considering the structure of the launch complex, the prevailing winds, the terrain, and predictions of the Rocket Exhaust Effluent Diffusion Model (REEDM). Fifty vegetation transects were established and sampled in March 1986 and resampled in September 1986. A vegetation map was prepared for six Master Planning maps surrounding SLC-6 using LANDSAT Thematic Mapper imagery as well as color and color infrared aerial photography. Soil samples were collected form the 0 to 7.5 cm layer at all transects in the wet season and at a subsample of the transects in the dry season and analyzed for pH, organic matter, conductivity, cation exchange capacity, exchangeable Ca, Mg, Na, K, and Al, available NH3-N, PO4-P, Cu, Fe, Mn, Zn, and TKN.

Groundwater flow, nutrient, and stable isotope dynamics in the parafluvial-hyporheic zone of the regulated Lower Colorado River (Texas, USA) over the course of a small flood

NASA Astrophysics Data System (ADS)

Briody, Alyse C.; Cardenas, M. Bayani; Shuai, Pin; Knappett, Peter S. K.; Bennett, Philip C.

2016-06-01

Periodic releases from an upstream dam cause rapid stage fluctuations in the Lower Colorado River near Austin, Texas, USA. These daily pulses modulate fluid exchange and residence times in the hyporheic zone where biogeochemical reactions are typically pronounced. The effects of a small flood pulse under low-flow conditions on surface-water/groundwater exchange and biogeochemical processes were studied by monitoring and sampling from two dense transects of wells perpendicular to the river. The first transect recorded water levels and the second transect was used for water sample collection at three depths. Samples were collected from 12 wells every 2 h over a 24-h period which had a 16-cm flood pulse. Analyses included nutrients, carbon, major ions, and stable isotopes of water. The relatively small flood pulse did not cause significant mixing in the parafluvial zone. Under these conditions, the river and groundwater were decoupled, showed potentially minimal mixing at the interface, and did not exhibit any discernible denitrification of river-borne nitrate. The chemical patterns observed in the parafluvial zone can be explained by evaporation of groundwater with little mixing with river water. Thus, large pulses may be necessary in order for substantial hyporheic mixing and exchange to occur. The large regulated river under a low-flow and small flood pulse regime functioned mainly as a gaining river with little hydrologic connectivity beyond a narrow hyporheic zone.

Cucumber plants (cucumis sativus l.) growth and crop yield of chicken manure fertilized with plant spacing

NASA Astrophysics Data System (ADS)

Pratiwi Aritonang, Sri; Panjaitan, Ernitha; Parsaulian Tondang, Fetrus

2018-03-01

The research was conducted in Tanjung Sari, Kecamatan Medan Selayang Kotamadya Medan ± 32 meters above sea level. It started since July 2016 to September 2016. It was designed with randomization block design with two factorial experiments which are chicken manure and plant spacing. First factor was 4 doses of chicken manure, symbolized by K; K0 = 1.5 kg/plot, K1 = 2 kg/plot, K2 = 2.5 kg/plot and K3 = 3 kg/plot. Second was 4 different plant spacing, symbolized by J; J0 = 30 cm x 60 cm, J1 =: 35 cm x 60 cm, J2 = 40 cm x 60 cm and J3 = 45 cm x 60 cm. The result shows that giving 3kg/plot of chicken manure increases plant height to 162.15 cm with 22.44 number of leaves. Fresh fruits per sample was weight 1121.88 g and per plot is 4.52 kg with 9.17 and 36.67 units of fruits per sample and plot respectively. With 45 cm x 60 cm (J3) for plant spacing gives a plant with the height of 160.51 cm and 22.85 number of leaves. Fresh fruits obtained is 1216.67 g and 9.33 units per sample while per plot gives 4.90 kg and 7.33 units of fresh fruits. This plant spacing leads to a better output for the yield compared to narrower spacing. There are no interaction between chicken manure dosage and plant spacing towards plant height, number of leaves, fresh fruits weight and units per sample and plot.

Hydrologic and geomorphic data from the Piceance Basin, Colorado, 1972-77

USGS Publications Warehouse

Frickel, Donald G.

1978-01-01

Erosion measurements made during the period 1972-77 in the Piceance basin of northwestern Colorado are presented in tabular form. Most of the measurements consist of repeated surveys of ground-surface altitudes along monumented transects at 45 hillslope sites and 121 channel sites. The sites were generally resurveyed annualy and after significant hydrologic events. Also included are precipitation, runoff, and sediment-yield data for five small plots with different physical characteristics. The data were collected as part of erosion rate, sediment transport, and channel morphology studies being conducted in conjunction with development of the oil-shale resource of the area. The channel measurements were made to determine rates of aggradation , degradation, and lateral movement. The hillslope measurements were obtained to show rates of soil erosion in the area. (Woodard-USGS)

The Distribution between the Dissolved and the Particulate Forms of 49 Metals across the Tigris River, Baghdad, Iraq

PubMed Central

Hamad, Samera Hussein; Schauer, James Jay; Shafer, Martin Merrill; Abed Al-Raheem, Esam; Satar, Hyder

2012-01-01

The distribution of dissolved and particulate forms of 49 elements was investigated along transect of the Tigris River (one of the major rivers of the world) within Baghdad city and in its major tributary (Diyala River) from 11 to 28 July 2011. SF-ICP-MS was used to measure total and filterable elements at 17 locations along the Tigris River transect, two samples from the Diyala River, and in one sample from the confluence of the two rivers. The calculated particulate forms were used to determine the particle-partition coefficients of the metals. No major changes in the elements concentrations down the river transect. Dissolved phases dominated the physical speciation of many metals (e.g., As, Mo, and Pt) in the Tigris River, while Al, Fe, Pb, Th, and Ti were exhibiting high particulate fractions, with a trend of particle partition coefficients of [Ti(40) > Th(35) > Fe(15) > Al(13) > Pb(4.5)] ∗ 106 L/kg. Particulate forms of all metals exhibited high concentrations in the Diyala River, though the partition coefficients were low due to high TSS (~270 mg/L). A comparison of Tigris with the major rivers of the world showed that Tigris quality in Baghdad is comparable to Seine River quality in Paris. PMID:23304083

Do sampling methods differ in their utility for ecological monitoring? Comparison of line-point intercept, grid-point intercept, and ocular estimate methods

USDA-ARS?s Scientific Manuscript database

This study compared the utility of three sampling methods for ecological monitoring based on: interchangeability of data (rank correlations), precision (coefficient of variation), cost (minutes/transect), and potential of each method to generate multiple indicators. Species richness and foliar cover...

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys.

PubMed

Futch, J Carrie; Griffin, Dale W; Lipp, Erin K

2010-04-01

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys

USGS Publications Warehouse

Futch, J. Carrie; Griffin, Dale W.; Lipp, Erin K.

2010-01-01

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.

Morphological and Genetic Variation along a North-to-South Transect in Stipa purpurea, a Dominant Grass on the Qinghai-Tibetan Plateau: Implications for Response to Climate Change

PubMed Central

You, Jianling; Qi, Danhui; Zhou, Yin; Chen, Jiakuan; Song, Zhiping

2016-01-01

Estimating the potential of species to cope with rapid environmental climatic modifications is of vital importance for determining their future viability and conservation. The variation between existing populations along a climatic gradient may predict how a species will respond to future climate change. Stipa purpurea is a dominant grass species in the alpine steppe and meadow of the Qinghai-Tibetan Plateau (QTP). Ecological niche modelling was applied to S. purpurea, and its distribution was found to be most strongly correlated with the annual precipitation and the mean temperature of the warmest quarter. We established a north-to-south transect over 2000 km long on the QTP reflecting the gradients of temperature and precipitation, and then we estimated the morphological by sampling fruited tussocks and genetic divergence by using 11 microsatellite markers between 20 populations along the transect. Reproductive traits (the number of seeds and reproductive shoots), the reproductive-vegetative growth ratio and the length of roots in the S. purpurea populations varied significantly with climate variables. S. purpurea has high genetic diversity (He = 0.585), a large effective population size (Ne >1,000), and a considerable level of gene flow between populations. The S. purpurea populations have a mosaic genetic structure: some distant populations (over 1000 km apart) clustered genetically, whereas closer populations (< 100 km apart) had diverged significantly, suggesting local adaptation. Asymmetrical long-distance inter-population gene flow occurs along the sampling transect and might be mediated by seed dispersal via migratory herbivores, such as the chiru (Pantholops hodgsonii). These findings suggest that population performance variation and gene flow both facilitate the response of S. purpurea to climate change. PMID:27580056

Morphological and Genetic Variation along a North-to-South Transect in Stipa purpurea, a Dominant Grass on the Qinghai-Tibetan Plateau: Implications for Response to Climate Change.

PubMed

Liu, Wensheng; Zhao, Yao; You, Jianling; Qi, Danhui; Zhou, Yin; Chen, Jiakuan; Song, Zhiping

2016-01-01

Estimating the potential of species to cope with rapid environmental climatic modifications is of vital importance for determining their future viability and conservation. The variation between existing populations along a climatic gradient may predict how a species will respond to future climate change. Stipa purpurea is a dominant grass species in the alpine steppe and meadow of the Qinghai-Tibetan Plateau (QTP). Ecological niche modelling was applied to S. purpurea, and its distribution was found to be most strongly correlated with the annual precipitation and the mean temperature of the warmest quarter. We established a north-to-south transect over 2000 km long on the QTP reflecting the gradients of temperature and precipitation, and then we estimated the morphological by sampling fruited tussocks and genetic divergence by using 11 microsatellite markers between 20 populations along the transect. Reproductive traits (the number of seeds and reproductive shoots), the reproductive-vegetative growth ratio and the length of roots in the S. purpurea populations varied significantly with climate variables. S. purpurea has high genetic diversity (He = 0.585), a large effective population size (Ne >1,000), and a considerable level of gene flow between populations. The S. purpurea populations have a mosaic genetic structure: some distant populations (over 1000 km apart) clustered genetically, whereas closer populations (< 100 km apart) had diverged significantly, suggesting local adaptation. Asymmetrical long-distance inter-population gene flow occurs along the sampling transect and might be mediated by seed dispersal via migratory herbivores, such as the chiru (Pantholops hodgsonii). These findings suggest that population performance variation and gene flow both facilitate the response of S. purpurea to climate change.

Status of important prey fishes in the U.S. waters of Lake Ontario, 2013: Introduction and methods, alewife, rainbow smelt, sculpins, and round goby

USGS Publications Warehouse

Walsh, Maureen; Weidel, Brian C.; Connerton, Michael J.

2014-01-01

Lake Ontario has a mean depth of 86 m (282 ft) and a maximum depth of 244 m (801 ft) (Herdendorf 1982). The southern, New York portion of the lake has the deepest water (Figure 1). In New York waters, about 67% of the lake is <160 m (525 ft) deep and about 82% of the lake is <180 m (591 ft) deep. The U.S. Geological Survey (USGS) and New York State Department of Environmental Conservation (NYSDEC) have cooperatively assessed Lake Ontario prey fishes each year since 1978. Bottom trawl assessments were initially focused on Alewife Alosa pseudoharengus (April), Rainbow Smelt Osmerus mordax (June), and Slimy Sculpin Cottus cognatus (October). Seasonal survey timing corresponded to the peak catches in 1972 when collections were made every month May to October (Owens et al. 2003). Twelve transects were established at approximately 25-km intervals along the U.S. shoreline (Figure 2). Alewife assessment was conducted at all transects, Rainbow Smelt assessment at all transects except Fair Haven, and six transects representing eastern, southern, and western lake areas were sampled for Slimy Sculpin (Figure 2). Changes in the Lake Ontario ecosystem (species invasion, oligotrophication, native species rebound) require ongoing evaluation of current methods which sometimes necessitate redistribution of trawl effort, or changes in sampling designs and/or gear. For instance, the spring Alewife assessment is now used also to assess invasive Round Goby Neogobius melanostomus population dynamics. Likewise, the fall benthic fish assessment (formerly sculpin assessment) now also tracks dynamics of the rebounding native Deepwater Sculpin Myoxocephalus thompsonii population, the apparent declining population of Slimy Sculpin, and fall distribution of Round Goby.

SnagPRO: snag and tree sampling and analysis methods for wildlife

Treesearch

Lisa J. Bate; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

2008-01-01

We describe sampling methods and provide software to accurately and efficiently estimate snag and tree densities at desired scales to meet a variety of research and management objectives. The methods optimize sampling effort by choosing a plot size appropriate for the specified forest conditions and sampling goals. Plot selection and data analyses are supported by...

The importance of plot size and the number of sampling seasons on capturing macrofungal species richness.

PubMed

Li, Huili; Ostermann, Anne; Karunarathna, Samantha C; Xu, Jianchu; Hyde, Kevin D; Mortimer, Peter E

2018-07-01

The species-area relationship is an important factor in the study of species diversity, conservation biology, and landscape ecology. A deeper understanding of this relationship is necessary, in order to provide recommendations on how to improve the quality of data collection on macrofungal diversity in different land use systems in future studies, a systematic assessment of methodological parameters, in particular optimal plot sizes. The species-area relationship of macrofungi in tropical and temperate climatic zones and four different land use systems were investigated by determining the macrofungal species richness in plot sizes ranging from 100 m 2 to 10 000 m 2 over two sampling seasons. We found that the effect of plot size on recorded species richness significantly differed between land use systems with the exception of monoculture systems. For both climate zones, land use system needs to be considered when determining optimal plot size. Using an optimal plot size was more important than temporal replication (over two sampling seasons) in accurately recording species richness. Copyright © 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Collaboration During the NASA ABoVE Airborne SAR Campaign: Sampling Strategies Used by NGEE Arctic and Other Partners in Alaska and Western Canada

NASA Astrophysics Data System (ADS)

Wullschleger, S. D.; Charsley-Groffman, L.; Baltzer, J. L.; Berg, A. A.; Griffith, P. C.; Jafarov, E. E.; Marsh, P.; Miller, C. E.; Schaefer, K. M.; Siqueira, P.; Wilson, C. J.; Kasischke, E. S.

2017-12-01

There is considerable interest in using L- and P-band Synthetic Aperture Radar (SAR) data to monitor variations in aboveground woody biomass, soil moisture, and permafrost conditions in high-latitude ecosystems. Such information is useful for quantifying spatial heterogeneity in surface and subsurface properties, and for model development and evaluation. To conduct these studies, it is desirable that field studies share a common sampling strategy so that the data from multiple sites can be combined and used to analyze variations in conditions across different landscape geomorphologies and vegetation types. In 2015, NASA launched the decade-long Arctic-Boreal Vulnerability Experiment (ABoVE) to study the sensitivity and resilience of these ecosystems to disturbance and environmental change. NASA is able to leverage its remote sensing strengths to collect airborne and satellite observations to capture important ecosystem properties and dynamics across large spatial scales. A critical component of this effort includes collection of ground-based data that can be used to analyze, calibrate and validate remote sensing products. ABoVE researchers at a large number of sites located in important Arctic and boreal ecosystems in Alaska and western Canada are following common design protocols and strategies for measuring soil moisture, thaw depth, biomass, and wetland inundation. Here we elaborate on those sampling strategies as used in the 2017 summer SAR campaign and address the sampling design and measurement protocols for supporting the ABoVE aerial activities. Plot size, transect length, and distribution of replicates across the landscape systematically allowed investigators to optimally sample a site for soil moisture, thaw depth, and organic layer thickness. Specific examples and data sets are described for the Department of Energy's Next-Generation Ecosystem Experiments (NGEE Arctic) project field sites near Nome and Barrow, Alaska. Future airborne and satellite campaigns will be conducted by the NASA ABoVE team and additional collaboration is encouraged.

Estimating the quadratic mean diameter of fine woody debris for forest type groups of the United States

Treesearch

Christopher W. Woodall; Vicente J. Monleon

2009-01-01

The Forest Inventory and Analysis program of the Forest Service, U.S. Department of Agriculture conducts a national inventory of fine woody debris (FWD); however, the sampling protocols involve tallying only the number of FWD pieces by size class that intersect a sampling transect with no measure of actual size. The line intersect estimator used with those samples...

Propagation of vent CO2 in a subtropical shallow-water ecosystem assessed by stable carbon isotopes

NASA Astrophysics Data System (ADS)

Cheng, Y. F.; Chen, C. T. A.; Liao, Y. M.; Lin, Y. S.

2016-02-01

Carbon cycle of the ocean plays an important role in the global change associated with the emission of CO2. Anthropogenic CO2 dissolves in seawater, changes carbon chemistry of the ocean, and affects marine life in different and complicated ways. In this study, we investigated stable carbon isotope systematics of a shallow-water hydrothermal field near the Kueishantao Islet off NE Taiwan, which has vent gas composition dominated by CO2 and world record breaking low pH hydrothermal fluids. By studying this natural laboratory of ocean acidification, we aim at clarifying to which extent the high dosage of CO2 propagates in the subtropical shallow-water ecosystem, and how it affects the carbon cycle. Samples of seawater and suspended particles were collected from stations of two nearshore-offshore transects, one with hydrothermal vents at the nearshore end (Transect M, 1230 m long) and the other serving as the baseline (Transect B, 1560 m long). Surface seawater of Transect M showed increasing pH in the offshore direction, from 5.8 at the vent mouths to 7.6 at the most distant station. In contrast, pH of surface water decreased seaward from 8.0 to 7.8 in Transect B. The δ13C values of the vent CO2 averaged -6.4‰, consistent with the range attributed to mantle CO2. Seawater DIC δ13C values of Transect M were 13C-depleted (as negative as -2.5‰) at the vent mouths, and became increasingly 13C-enriched till 0.7‰ at the most distant station. This pattern is in clear contrast to that of Transect B, the DIC δ13C values of which decreased from 0.7 to 0.6 ‰ in the offshore direction. We concluded that the vent CO2 has propagated in the surface ocean at least >700 m away from the hydrothermal field. Our next step is to explore how the vent CO2 affects the stable carbon isotopes of particulate organic matter, and to assess the effect of vent CO2 using quantitative approaches.

Location and description of transects for ecological studies in floodplain forests of the lower Suwannee River, Florida

USGS Publications Warehouse

Lewis, L.J.; Light, H.M.; Darst, M.R.

2001-01-01

Twelve transects were established in floodplain forests along the lower Suwannee River, Florida, as the principal data collection sites for a comprehensive study conducted by the U.S. Geological Survey and the Suwannee River Water Management District from 1996 to 2001. Data collected along the 12 transects included hydrologic conditions, land-surface elevations, soils, and vegetation of floodplain forests in relation to river flow. Transect locations are marked in the field with permanent markers at approximately 30 meter intervals. Detailed descriptions of the 12 transects and their locations are provided so that they can be used for future ecological studies. Descriptions of the transects include contact information necessary for access to the property on which the transects are located, maps showing transect locations and routes from the nearest city or major road, small scale maps of each transect showing marker locations, latitude and longitude of each marker, compass bearings of each transect line and graphs showing land-surface elevations of the transect with marker locations.

Satellite-Based Evidence for Shrub and Graminoid Tundra Expansion in Northern Quebec from 1986-2010

NASA Technical Reports Server (NTRS)

McManus, K. M.; Morton, D. C.; Masek, J. G.; Wang, D.; Sexton, J. O.; Nagol, J.; Ropars, P.; Boudreau, S.

2012-01-01

Global vegetation models predict rapid poleward migration of tundra and boreal forest vegetation in response to climate warming. Local plot and air-photo studies have documented recent changes in high-latitude vegetation composition and structure, consistent with warming trends. To bridge these two scales of inference, we analyzed a 24-year (1986-2010) Landsat time series in a latitudinal transect across the boreal forest-tundra biome boundary in northern Quebec province, Canada. This region has experienced rapid warming during both winter and summer months during the last forty years. Using a per-pixel (30 m) trend analysis, 30% of the observable (cloud-free) land area experienced a significant (p < 0.05) positive trend in the Normalized Difference Vegetation Index (NDVI). However, greening trends were not evenly split among cover types. Low shrub and graminoid tundra contributed preferentially to the greening trend, while forested areas were less likely to show significant trends in NDVI. These trends reflect increasing leaf area, rather than an increase in growing season length, because Landsat data were restricted to peak-summer conditions. The average NDVI trend (0.007/yr) corresponds to a leaf-area index (LAI) increase of 0.6 based on the regional relationship between LAI and NDVI from the Moderate Resolution Spectroradiometer (MODIS). Across the entire transect, the area-averaged LAI increase was 0.2 during 1986-2010. A higher area-averaged LAI change (0.3) within the shrub-tundra portion of the transect represents a 20-60% relative increase in LAI during the last two decades. Our Landsat-based analysis subdivides the overall high-latitude greening trend into changes in peak-summer greenness by cover type. Different responses within and among shrub, graminoid, and tree-dominated cover types in this study indicate important fine-scale heterogeneity in vegetation growth. Although our findings are consistent with community shifts in low-biomass vegetation types over multi-decadal time scales, the response in tundra and forest ecosystems to recent warming was not uniform.

Methodological considerations of terrestrial laser scanning for vegetation monitoring in the sagebrush steppe

USGS Publications Warehouse

Anderson, Kyle E.; Glenn, Nancy; Spaete, Lucas; Shinneman, Douglas; Pilliod, David S.; Arkle, Robert; McIlroy, Susan; Derryberry, DeWayne R.

2017-01-01

Terrestrial laser scanning (TLS) provides fast collection of high-definition structural information, making it a valuable field instrument to many monitoring applications. A weakness of TLS collections, especially in vegetation, is the occurrence of unsampled regions in point clouds where the sensor’s line-of-sight is blocked by intervening material. This problem, referred to as occlusion, may be mitigated by scanning target areas from several positions, increasing the chance that any given area will fall within the scanner’s line-of-sight from at least one position. Because TLS collections are often employed in remote regions where the scope of sampling is limited by logistical factors such as time and battery power, it is important to design field protocols which maximize efficiency and support increased quantity and quality of the data collected. This study informs researchers and practitioners seeking to optimize TLS sampling methods for vegetation monitoring in dryland ecosystems through three analyses. First, we quantify the 2D extent of occluded regions based on the range from single scan positions. Second, we measure the efficacy of additional scan positions on the reduction of 2D occluded regions (area) using progressive configurations of scan positions in 1 ha plots. Third, we test the reproducibility of 3D sampling yielded by a 5-scan/ha sampling methodology using redundant sets of scans. Analyses were performed using measurements at analysis scales of 5 to 50 cm across the 1-ha plots, and we considered plots in grass and shrub-dominated communities separately. In grass-dominated plots, a center-scan configuration and 5 cm pixel size sampled at least 90% of the area up to 18 m away from the scanner. In shrub-dominated plots, sampling at least 90% of the area was only achieved within a distance of 12 m. We found that 3 and 5 scans/ha are needed to sample at least ~ 70% of the total area (1 ha) in the grass and shrub-dominated plots, respectively, using 5 cm pixels to measure sampling presence-absence. The reproducibility of 3D sampling provided by a 5 position scan layout across 1-ha plots was 50% (shrub) and 70% (grass) using a 5-cm voxel size, whereas at the 50-cm voxel scale, reproducibility of sampling was nearly 100% for all plot types. Future studies applying TLS in similar dryland environments for vegetation monitoring may use our results as a guide to efficiently achieve sampling coverage and reproducibility in datasets.

Methodological considerations of terrestrial laser scanning for vegetation monitoring in the sagebrush steppe.

PubMed

Anderson, Kyle E; Glenn, Nancy F; Spaete, Lucas P; Shinneman, Douglas J; Pilliod, David S; Arkle, Robert S; McIlroy, Susan K; Derryberry, DeWayne R

2017-10-23

Terrestrial laser scanning (TLS) provides fast collection of high-definition structural information, making it a valuable field instrument to many monitoring applications. A weakness of TLS collections, especially in vegetation, is the occurrence of unsampled regions in point clouds where the sensor's line-of-sight is blocked by intervening material. This problem, referred to as occlusion, may be mitigated by scanning target areas from several positions, increasing the chance that any given area will fall within the scanner's line-of-sight from at least one position. Because TLS collections are often employed in remote regions where the scope of sampling is limited by logistical factors such as time and battery power, it is important to design field protocols which maximize efficiency and support increased quantity and quality of the data collected. This study informs researchers and practitioners seeking to optimize TLS sampling methods for vegetation monitoring in dryland ecosystems through three analyses. First, we quantify the 2D extent of occluded regions based on the range from single scan positions. Second, we measure the efficacy of additional scan positions on the reduction of 2D occluded regions (area) using progressive configurations of scan positions in 1 ha plots. Third, we test the reproducibility of 3D sampling yielded by a 5-scan/ha sampling methodology using redundant sets of scans. Analyses were performed using measurements at analysis scales of 5 to 50 cm across the 1-ha plots, and we considered plots in grass and shrub-dominated communities separately. In grass-dominated plots, a center-scan configuration and 5 cm pixel size sampled at least 90% of the area up to 18 m away from the scanner. In shrub-dominated plots, sampling at least 90% of the area was only achieved within a distance of 12 m. We found that 3 and 5 scans/ha are needed to sample at least ~ 70% of the total area (1 ha) in the grass and shrub-dominated plots, respectively, using 5 cm pixels to measure sampling presence-absence. The reproducibility of 3D sampling provided by a 5 position scan layout across 1-ha plots was 50% (shrub) and 70% (grass) using a 5-cm voxel size, whereas at the 50-cm voxel scale, reproducibility of sampling was nearly 100% for all plot types. Future studies applying TLS in similar dryland environments for vegetation monitoring may use our results as a guide to efficiently achieve sampling coverage and reproducibility in datasets.

The Distribution and Abundance of Leaf Litter Arthropods in MOFEP Sites 1, 2, and 3

Treesearch

Jan Weaver; Sarah Heyman

1997-01-01

In June 1993, we collected 144 leaf litter samples from 36 plots (4 samples/plot) located in MOFEP forest sites 1, 2 and 3. Half of the plots were placed randomly on northeast-facing stands (ELT 18), and half randomly placed on southwest-facing stands (ELT 17). Arthropods were extracted using Tullgren funnels, and then sorted into morpho-species, counted, and measured...

Effects of cycle length and plot density on estimators for a national-scale forest monitoring sample design

Treesearch

Francis A. Roesch; Todd A. Schroeder; James T. Vogt

2017-01-01

The resilience of a National Forest Inventory and Monitoring sample design can sometimes depend upon the degree to which it can adapt to fluctuations in funding. If a budget reduction necessitates the observation of fewer plots per year, some practitioners weigh the problem as a tradeoff between reducing the total number of plots and measuring the original number of...

Analysis of arson fire debris by low temperature dynamic headspace adsorption porous layer open tubular columns.

PubMed

Nichols, Jessica E; Harries, Megan E; Lovestead, Tara M; Bruno, Thomas J

2014-03-21

In this paper we present results of the application of PLOT-cryoadsorption (PLOT-cryo) to the analysis of ignitable liquids in fire debris. We tested ignitable liquids, broadly divided into fuels and solvents (although the majority of the results presented here were obtained with gasoline and diesel fuel) on three substrates: Douglas fir, oak plywood and Nylon carpet. We determined that PLOT-cryo allows the analyst to distinguish all of the ignitable liquids tested by use of a very rapid sampling protocol, and performs better (more recovered components, higher efficiency, lower elution solvent volumes) than a conventional purge and trap method. We also tested the effect of latency (the time period between applying the ignitable liquid and ignition), and we tested a variety of sampling times and a variety of PLOT capillary lengths. Reliable results can be obtained with sampling time periods as short as 3min, and on PLOT capillaries as short as 20cm. The variability of separate samples was also assessed, a study made possible by the high throughput nature of the PLOT-cryo method. We also determined that the method performs better than the conventional carbon strip method that is commonly used in fire debris analysis. Published by Elsevier B.V.

Roadside versus remote: Is the habitat sampled by the Breeding Bird Survey in Maryland representative of statewide conditions?

USGS Publications Warehouse

Boone, D.D.; Sauer, J.R.; Thomas, I.; Handley, Lawrence R.; D'Erchia, Frank J.; Charron, Tammy M.

2000-01-01

The North American Breeding Bird Survey (BBS) has received criticism that the bird habitat sampled along the 24.5 mile long roadside transects may not be proportional to regional totals. If true, trends in bird populations recorded by the BBS may not be sensitive predictors of regional or continental change in songbird abundance. To test whether the approximately 60 BBS routes in Maryland representatively sample the state's habitat, a geographic information system (GIS) database was compiled of significant bird habitat identified from remotely sensed landcover and land-use information (e.g., Multi-Resolution Land Characteristics Consortiumclassified Landsat Thematic Mapper imagery, etc.). These GIS data layers were analyzed to determine the statewide acreage of identified habitats as well as the acreage in each of the major physiographic regions of Maryland. Regional and statewide totals were also extracted for the subsample of habitat within 30 m of the BBS transects. The results of the comparison of regional and statewide habitat totals with the BBS sample showed very low proportional difference for nearly all of the identified habitat parameters. For Maryland and perhaps other urbanizing states, the BBS provides an accurate sample of available songbird habitats.

Water table and overbank flow frequency changes due to suburbanization-induced channel incision, Virginia Coastal Plain, USA

NASA Astrophysics Data System (ADS)

Hancock, G.; Mattell, N.; Christianson, E.; Wacksman, J.

2004-12-01

Channel incision is a widely observed response to increased flow in urbanized watersheds, but the effects of channel lowering on riparian water tables is not well documented. In a rapidly incising suburban stream in the Virginia Coastal Plain, we hypothesize that incision has lowered floodplain water tables and decreased the overbank flow frequency, and suggest these changes impact vegetation distribution in a diverse, protected riparian habitat. The monitored stream is a tributary to the James River draining 1.3 km2, of which 15% is impervious cover. Incision has occurred largely through upstream migration of a one m high knickpoint at a rate of 1-2 m/yr, primarily during high flow events. We installed 33 wells in six floodplain transects to assess water table elevations beneath the floodplain adjacent to the incising stream. To document the impacts of incision, two transects are located 30 and 50 m upstream of the knickpoint in unincised floodplain, and the remainder are 5, 30, 70, and 100 m downstream of the knickpoint in incised floodplain. In one transect above and two below, pressure transducers attached to dataloggers provide a high-resolution record of water table response to storm events. Significant differences have been observed in the water table above and below the knickpoint. Above the knickpoint, the water table is relatively flat and is 0.2-0.4 m below the floodplain surface. Water table response to precipitation events is nearly immediate, with the water table rising to the floodplain surface in significant rainfall events. In the transect immediately downstream of the knickpoint, the water table possesses a steep gradient, rising from ~1 m below the floodplain at the stream to 0.3 m below the surface within 20 m. In the most downstream transects, the water table is relatively flat, but is one m below the floodplain surface, equivalent to the depth of incision generated by knickpoint passage. Upstream of the knickpoint, overbank flooding occurs frequently, while below the knickpoint the majority of storm flow is contained within the incised channel and occupation of the floodplain is rare. Plant diversity surveys reveal differences in the total density of herbaceous growth and species distribution between the floodplain above and below the knickpoint. Results from >100 plots show that there is more leaf litter, less exposed ground, and a decrease in floodplain species cover in the incised portion of the floodplain. The changes in flood frequency and water table elevation appear to have allowed one invasive species, Japanese stilt grass (Microstegium vimineum), to become dominant in the floodplain understory, displacing native wetland species.

Lead transport into Bayou Trepagnier wetlands in Louisiana, USA.

PubMed

Devall, Margaret S; Thien, Leonard B; Ellgaard, Erik; Flowers, George

2006-01-01

Establishment of a petroleum refinery in 1916 near the headwaters of Bayou Trepagnier with subsequent dredging of the bayou resulted in spoil banks containing high levels of Pb. A large swamp abuts the eastern bank of the bayou. Cores were taken from 15 baldcypress [Taxodium distichum (L.) Richard] trees growing in the swamp along a 610-m transect (nine trees) and a 183-m transect (six trees) running perpendicular from the spoil bank. The cores were crossdated, annual rings were measured, and 5-yr segments of the cores were prepared and analyzed for heavy metals. Soil samples were collected along one transect and analyzed for metals. Levels of Pb in Bayou Trepagnier swamp trees were compared to levels in nine baldcypress trees growing along Stinking Bayou, a reference area. During the last 100 yr, Pb in growth rings of swamp baldcypress trees averaged 8.6 mg/kg (SD 4.88) along one transect and 7.9 mg/kg (SD 5.39) along the other. Lead in the soil along the first transect dropped from >2700 mg/kg (spoil bank) to 10 mg/kg at 420 m into the swamp. Baldcypress trees growing near the refinery on the spoil bank along Bayou Trepagnier (covered in an earlier study) averaged 4.5 mg/kg Pb, and trees along Stinking Bayou averaged 2.1 mg/kg. Trees in the swamp soil with 10 to 425 mg/kg Pb concentrated much more Pb than trees growing on the heavily polluted bank. Greater uptake of Pb by trees in the swamp is discussed in terms of soil dynamics and Pb sources.

Efficacy of the organic-certified insecticide Diatect II against the boll weevil (Anthonomus grandis) in cotton.

PubMed

Sappington, Thomas W

2002-10-01

The efficacy of the organic insecticide Diatect II against boll weevil (Anthonomus grandis Boheman) in cotton (Gossypium hirsutum L) in the Lower Rio Grande Valley of Texas were assessed in small-plot field trials and greenhouse cage tests using azinphos-methyl treatments as a standard for comparison. Plastic sheets were placed in the furrows of the treated plots to retrieve boll weevils which dropped from the plants after being killed by the insecticides. Samples of live weevils taken by a tractor-mounted vacuum sampler revealed a modest, but significant, reduction in boll weevil populations in Diatect II plots. However, samples of dead weevils indicated that this reduction was due to movement of weevils out of the plots rather than to mortality. This interpretation is supported by greenhouse cage studies, where mortality in Diatect II treated cages was no greater than that in untreated control cages. The effects of insecticide treatments in small plots can be confounded easily and quickly by interplot movement of target insects. Although the relative effects of various compounds can usually be assessed by sampling the populations in plots soon after treatment, the best measure of efficacy is obtained by directly sampling insects that have died in the plot. This parameter is insulated from the effects of interplot movement, unless the toxicant is slow to immobilize the target insect. Taken together, our results indicate little efficacy by Diatect II against boll weevil under our test conditions.

Measuring pasture degradation on the Qinghai-Tibet Plateau using hyperspectral dissimilarities and indices

NASA Astrophysics Data System (ADS)

Meyer, Hanna; Lehnert, Lukas W.; Wang, Yun; Reudenbach, Christoph; Bendix, Jörg

2013-10-01

Despite that relevance of pasture degradation on the Qinghai-Tibet Plateau (QTP) is widely postulated, its extent is still unknown. However, livestock grazing is widely accepted as a major factor. This study investigated spectral differences of vegetation patterns along gradients of grazing intensities using plot-based hyperspectral measurements. The measurements were used to define spectral indicators for pasture degradation, which were applied to map asserted proxies for degradation from satellite images. For this purpose, hyperspectral measurements were taken at 11 sites on the north-eastern QTP using a transect design from heavy grazing and therefore asserted degradation near the settlement to less degradation with increasing distance. Potential spectral indicators for degradation were derived from the spectra by calculating the size of continuum removed absorption features and narrow-band indices (NBI). They were compared between degraded and less degraded plots. Linear regressions between proxies and each of the potential spectral indicators were calculated to assess its predictive power. The findings were transferred to larger scales by applying the indicators on two WorldView-2 (WV-2) scenes. Spectral differences between degraded and less degraded plots were obvious regarding a wide range of tested indicators. Several NBIs were considered as good indicators for vegetation cover and species numbers. WV-2 images could be successfully classified into vegetation cover whilst the estimation of species numbers was afflicted with uncertainties. The results demonstrate the potential to estimate degradation proxies using spectrometer measurements and satellite data. Applying these techniques will contribute to a better estimation of spatial degradation patterns on the QTP.

Post-fire salvage logging alters species composition and reduces cover, richness, and diversity in Mediterranean plant communities.

PubMed

Leverkus, Alexandro B; Lorite, Juan; Navarro, Francisco B; Sánchez-Cañete, Enrique P; Castro, Jorge

2014-01-15

An intense debate exists on the effects of post-fire salvage logging on plant community regeneration, but scant data are available derived from experimental studies. We analyzed the effects of salvage logging on plant community regeneration in terms of species richness, diversity, cover, and composition by experimentally managing a burnt forest on a Mediterranean mountain (Sierra Nevada, S Spain). In each of three plots located at different elevations, three replicates of three treatments were implemented seven months after the fire, differing in the degree of intervention: "Non-Intervention" (all trees left standing), "Partial Cut plus Lopping" (felling 90% of the trees, cutting the main branches, and leaving all the biomass in situ), and "Salvage Logging" (felling and piling the logs, and masticating the woody debris). Plant composition in each treatment was monitored two years after the fire in linear point transects. Post-fire salvage logging was associated with reduced species richness, Shannon diversity, and total plant cover. Moreover, salvaged sites hosted different species assemblages and 25% lower cover of seeder species (but equal cover of resprouters) compared to the other treatments. Cover of trees and shrubs was also lowest in Salvage Logging, which could suggest a potential slow-down of forest regeneration. Most of these results were consistent among the three plots despite plots hosting different plant communities. Concluding, our study suggests that salvage logging may reduce species richness and diversity, as well as the recruitment of woody species, which could delay the natural regeneration of the ecosystem. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gap characteristics of southeastern Ohio second-growth forests

Treesearch

David M. Hix; Katherine K. Helfrich

2003-01-01

Transect sampling was used to assess the features of 30 gaps encountered in upland oak stands on the Wayne National Forest. Tip-ups caused the most canopy gaps (52 percent), two-thirds of which were small (

Statistical Algorithms Accounting for Background Density in the Detection of UXO Target Areas at DoD Munitions Sites

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

Matzke, Brett D.; Wilson, John E.; Hathaway, J.

2008-02-12

Statistically defensible methods are presented for developing geophysical detector sampling plans and analyzing data for munitions response sites where unexploded ordnance (UXO) may exist. Detection methods for identifying areas of elevated anomaly density from background density are shown. Additionally, methods are described which aid in the choice of transect pattern and spacing to assure with degree of confidence that a target area (TA) of specific size, shape, and anomaly density will be identified using the detection methods. Methods for evaluating the sensitivity of designs to variation in certain parameters are also discussed. Methods presented have been incorporated into the Visualmore » Sample Plan (VSP) software (free at http://dqo.pnl.gov/vsp) and demonstrated at multiple sites in the United States. Application examples from actual transect designs and surveys from the previous two years are demonstrated.« less

Genome flux and stasis in a five millennium transect of European prehistory

PubMed Central

Gamba, Cristina; Jones, Eppie R.; Teasdale, Matthew D.; McLaughlin, Russell L.; Gonzalez-Fortes, Gloria; Mattiangeli, Valeria; Domboróczki, László; Kővári, Ivett; Pap, Ildikó; Anders, Alexandra; Whittle, Alasdair; Dani, János; Raczky, Pál; Higham, Thomas F. G.; Hofreiter, Michael; Bradley, Daniel G; Pinhasi, Ron

2014-01-01

The Great Hungarian Plain was a crossroads of cultural transformations that have shaped European prehistory. Here we analyse a 5,000-year transect of human genomes, sampled from petrous bones giving consistently excellent endogenous DNA yields, from 13 Hungarian Neolithic, Copper, Bronze and Iron Age burials including two to high (~22 × ) and seven to ~1 × coverage, to investigate the impact of these on Europe’s genetic landscape. These data suggest genomic shifts with the advent of the Neolithic, Bronze and Iron Ages, with interleaved periods of genome stability. The earliest Neolithic context genome shows a European hunter-gatherer genetic signature and a restricted ancestral population size, suggesting direct contact between cultures after the arrival of the first farmers into Europe. The latest, Iron Age, sample reveals an eastern genomic influence concordant with introduced Steppe burial rites. We observe transition towards lighter pigmentation and surprisingly, no Neolithic presence of lactase persistence. PMID:25334030

Genome flux and stasis in a five millennium transect of European prehistory.

PubMed

Gamba, Cristina; Jones, Eppie R; Teasdale, Matthew D; McLaughlin, Russell L; Gonzalez-Fortes, Gloria; Mattiangeli, Valeria; Domboróczki, László; Kővári, Ivett; Pap, Ildikó; Anders, Alexandra; Whittle, Alasdair; Dani, János; Raczky, Pál; Higham, Thomas F G; Hofreiter, Michael; Bradley, Daniel G; Pinhasi, Ron

2014-10-21

The Great Hungarian Plain was a crossroads of cultural transformations that have shaped European prehistory. Here we analyse a 5,000-year transect of human genomes, sampled from petrous bones giving consistently excellent endogenous DNA yields, from 13 Hungarian Neolithic, Copper, Bronze and Iron Age burials including two to high (~22 × ) and seven to ~1 × coverage, to investigate the impact of these on Europe's genetic landscape. These data suggest genomic shifts with the advent of the Neolithic, Bronze and Iron Ages, with interleaved periods of genome stability. The earliest Neolithic context genome shows a European hunter-gatherer genetic signature and a restricted ancestral population size, suggesting direct contact between cultures after the arrival of the first farmers into Europe. The latest, Iron Age, sample reveals an eastern genomic influence concordant with introduced Steppe burial rites. We observe transition towards lighter pigmentation and surprisingly, no Neolithic presence of lactase persistence.

Comparison of aboveground vegetation and soil seed bank composition at sites of different grazing intensity around a savanna-woodland watering point in West Africa.

PubMed

Sanou, Lassina; Zida, Didier; Savadogo, Patrice; Thiombiano, Adjima

2018-06-11

Grazing removes a plant's aboveground vegetative and reproductive tissues and can modify the soil seed bank, potentially impacting the restoration of preferred species. Knowledge about aboveground vegetation and species composition of soil seed bank and the processes that contribute to vegetation recovery on and surrounding watering points subjected to grazing is lacking. Successful restoration strategies hinge on addressing these knowledge gaps. We assessed the effects of livestock grazing on aboveground vegetation and soil seed bank characteristics along a river bank and surrounding areas subject to different grazing intensities and draw implications for restoration. Plots (50 × 50 m) were established along five transects representing differing levels of grazing intensity. Soil samples were taken from three layers within each plot to determine soil properties and species composition of soil seed bank using the seedling emergence method. Heavy grazing resulted in the disappearance of perennial grasses, a reduction in species diversity and a decrease in soil nutrients with increased soil depth. Overall, the similarity between the extant aboveground vegetation and flora within the soil seed bank was low. The soil seed bank was dominated by herbaceous species and two woody species, suggesting that many woody species are not accumulating in the soil. With increasing soil depth, the seed density and richness declined. Canonical correspondence analyses (CCAs) showed that emerged seedlings from the soil seed bank were significantly influenced by soil carbon, organic matter, total nitrogen, total potassium and soil cation exchange capacity. This finding suggests that current grazing practices have a negative impact on the vegetation surrounding watering points; hence there is a need for improved grazing management strategies and vegetation restoration in these areas. The soil seed bank alone cannot restore degraded river banks; active transfer of propagules from adjacent undisturbed forest areas is essential.

Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem

PubMed Central

Averett, Joshua P.; McCune, Bruce; Parks, Catherine G.; Naylor, Bridgett J.; DelCurto, Tim; Mata-González, Ricardo

2016-01-01

Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The importance of any one of these factors is debated and likely ecosystem dependent. We evaluated the importance of various correlates of plant invasions in the Wallowa Mountain Range of northeastern Oregon and explored whether non-native species distributions differed from native species along an elevation gradient. Vascular plant communities were sampled in summer 2012 along three mountain roads. Transects (n = 20) were evenly stratified by elevation (~70 m intervals) along each road. Vascular plant species abundances and environmental parameters were measured. We used indicator species analysis to identify habitat affinities for non-native species. Plots were ordinated in species space, joint plots and non-parametric multiplicative regression were used to relate species and community variation to environmental variables. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness occurring at mid–elevations. Species composition was strongly related to elevation and canopy openness. Overlays of trait and environmental factors onto non-metric multidimensional ordinations identified the montane-subalpine community transition and over-story canopy closure exceeding 60% as potential barriers to non-native species establishment. Unlike native species, non-native species showed little evidence for high-elevation or closed-canopy specialization. These data suggest that non-native plants currently found in the Wallowa Mountains are dependent on open canopies and disturbance for establishment in low and mid elevations. Current management objectives including restoration to more open canopies in dry Rocky Mountain forests, may increase immigration pressure of non-native plants from lower elevations into the montane and subalpine zones. PMID:26824750

Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem.

PubMed

Averett, Joshua P; McCune, Bruce; Parks, Catherine G; Naylor, Bridgett J; DelCurto, Tim; Mata-González, Ricardo

2016-01-01

Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The importance of any one of these factors is debated and likely ecosystem dependent. We evaluated the importance of various correlates of plant invasions in the Wallowa Mountain Range of northeastern Oregon and explored whether non-native species distributions differed from native species along an elevation gradient. Vascular plant communities were sampled in summer 2012 along three mountain roads. Transects (n = 20) were evenly stratified by elevation (~70 m intervals) along each road. Vascular plant species abundances and environmental parameters were measured. We used indicator species analysis to identify habitat affinities for non-native species. Plots were ordinated in species space, joint plots and non-parametric multiplicative regression were used to relate species and community variation to environmental variables. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness occurring at mid-elevations. Species composition was strongly related to elevation and canopy openness. Overlays of trait and environmental factors onto non-metric multidimensional ordinations identified the montane-subalpine community transition and over-story canopy closure exceeding 60% as potential barriers to non-native species establishment. Unlike native species, non-native species showed little evidence for high-elevation or closed-canopy specialization. These data suggest that non-native plants currently found in the Wallowa Mountains are dependent on open canopies and disturbance for establishment in low and mid elevations. Current management objectives including restoration to more open canopies in dry Rocky Mountain forests, may increase immigration pressure of non-native plants from lower elevations into the montane and subalpine zones.

Seasonal abundance and habitat use of bird species in and around Wondo Genet Forest, south-central Ethiopia.

PubMed

Girma, Zerihun; Mamo, Yosef; Mengesha, Girma; Verma, Ashok; Asfaw, Tsyon

2017-05-01

The habitat use and seasonal migratory pattern of birds in Ethiopia is less explored as compared to diversity studies. To this end, this study aimed at investigating the patterns of distribution related to seasonality and the effect of habitat characteristics (elevation, slope, and average vegetation height) on habitat use of birds of Wondo Genet Forest Patch. A stratified random sampling design was used to assess the avian fauna across the four dominant habitat types found in the study area: natural forest, wooded grassland, grassland, and agroforestry land. A point transect count was employed to investigate avian species richness and abundance per habitat type per season. Ancillary data, such as elevation above sea level, latitude and longitude, average vegetation height, and percent slope inclination, were recorded with a GPS and clinometers per plot. A total of 33 migratory bird species were recorded from the area, of which 20 species were northern (Palearctic) migrants while 13 were inter-African migrants. There was a significant difference in the mean abundance of migratory bird species between dry and wet seasons ( t  = 2.13, p  = .038, df  = 44). The variation in mean abundance per plot between the dry and wet seasons in the grassland habitat was significant ( t  = 2.35, p  = .051, df  = 7). In most habitat types during both dry and wet seasons, omnivore birds were the most abundant. While slope was a good predictor for bird species abundance in the dry season, altitude and average vegetation height accounted more in the wet season. The patch of forest and its surrounding is an important bird area for migratory, endemic, and global threatened species. Hence, it is conservation priority area, and the study suggests that conservation coupled with ecotourism development is needed for its sustainability.

Decadal changes in potassium, calcium, and magnesium in a deciduous forest soil

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

Mulholland, Patrick J; Johnson, Dale W.; Todd Jr, Donald E

2008-01-01

Decadal changes in soil exchangeable K{sup +}, Ca{sup 2+}, and Mg{sup 2+} concentrations and contents from 1972 to 2004 in eight intensively monitored plots on Walker Branch Watershed were compared with estimates of increments or decrements in vegetation and detritus. The results from these eight plots compared favorably with those from a more extensive set from 24 soil sampling plots sampled in 1972 and 2004. Increases in exchangeable K{sup +} were noted between 1972 and 1982, but few changes were noted between 1982 and 2004 despite significant increments in vegetation and detritus and significant potential losses by leaching. Total Kmore » contents of soils in the 0- to 60-cm sampling depth were very large and a slight amount of weathering could have replenished the K{sup +} lost from exchanges sites. With one notable exception, exchangeable Ca{sup 2+} and Mg{sup 2+} concentrations and contents decreased continuously during the sampling period. Decreases in exchangeable Ca{sup 2+} could be attributed mostly to increments in biomass and detritus, whereas decreases in exchangeable Mg{sup 2+} could not and were attributed to leaching. The major exception to these patterns was in the case of exchangeable Ca{sup 2+}, where significant increases were noted in one plot and attributed to Ca release from the decomposition of Ca-rich coarse woody debris from oak (Quercus spp.) mortality. With minor exceptions, soils and changes in soils among the eight intensively sampled core plots were similar to those in a more extensive set of plots distributed across the watershed. This study shows that averaging among plots can mask significant and important spatial patterns in soil change that must be taken into account in assessing long-term trends.« less

Phenotypic variation in California populations of valley oak (Quercus lobata Née) sampled along elevational gradients

Treesearch

Ana L. Albarrán-Lara; Jessica W. Wright; Paul F. Gugger; Annette Delfino-Mix; Juan Manuel Peñaloza-Ramírez; Victoria L. Sork

2015-01-01

California oaks exhibit tremendous phenotypic variation throughout their range. This variation reflects phenotypic plasticity in tree response to local environmental conditions as well as genetic differences underlying those phenotypes. In this study, we analyze phenotypic variation in leaf traits for valley oak adults sampled along three elevational transects and in...

Impacts of sampling design and estimation methods on nutrient leaching of intensively monitored forest plots in the Netherlands.

PubMed

de Vries, W; Wieggers, H J J; Brus, D J

2010-08-05

Element fluxes through forest ecosystems are generally based on measurements of concentrations in soil solution at regular time intervals at plot locations sampled in a regular grid. Here we present spatially averaged annual element leaching fluxes in three Dutch forest monitoring plots using a new sampling strategy in which both sampling locations and sampling times are selected by probability sampling. Locations were selected by stratified random sampling with compact geographical blocks of equal surface area as strata. In each sampling round, six composite soil solution samples were collected, consisting of five aliquots, one per stratum. The plot-mean concentration was estimated by linear regression, so that the bias due to one or more strata being not represented in the composite samples is eliminated. The sampling times were selected in such a way that the cumulative precipitation surplus of the time interval between two consecutive sampling times was constant, using an estimated precipitation surplus averaged over the past 30 years. The spatially averaged annual leaching flux was estimated by using the modeled daily water flux as an ancillary variable. An important advantage of the new method is that the uncertainty in the estimated annual leaching fluxes due to spatial and temporal variation and resulting sampling errors can be quantified. Results of this new method were compared with the reference approach in which daily leaching fluxes were calculated by multiplying daily interpolated element concentrations with daily water fluxes and then aggregated to a year. Results show that the annual fluxes calculated with the reference method for the period 2003-2005, including all plots, elements and depths, lies only in 53% of the cases within the range of the average +/-2 times the standard error of the new method. Despite the differences in results, both methods indicate comparable N retention and strong Al mobilization in all plots, with Al leaching being nearly equal to the leaching of SO(4) and NO(3) with fluxes expressed in mol(c) ha(-1) yr(-1). This illustrates that Al release, which is the clearest signal of soil acidification, is mainly due to the external input of SO(4) and NO(3).

The chemical characteristics of soil in control and experimentally thinned plots in mesic oak forests along a historical deposition gradient

Treesearch

Ralph E. J. Boerner; Elaine Kennedy Sutherland

1997-01-01

This study examined the variations in the chemical parameters of soils of seven forests located along a historical deposition gradient spanning 8.5° longitude from southern Illinois to central West Virginia. Four to six mature control plots were sampled on two of the sites, and two experimentally thinned and two control plots were sampled on the remaining five sites....

Characterizing the Phylogenetic Tree Community Structure of a Protected Tropical Rain Forest Area in Cameroon

PubMed Central

Munoz, François; Couteron, Pierre; Hardy, Olivier J.; Sonké, Bonaventure

2014-01-01

Tropical rain forests, the richest terrestrial ecosystems in biodiversity on Earth are highly threatened by global changes. This paper aims to infer the mechanisms governing species tree assemblages by characterizing the phylogenetic structure of a tropical rain forest in a protected area of the Congo Basin, the Dja Faunal Reserve (Cameroon). We re-analyzed a dataset of 11538 individuals belonging to 372 taxa found along nine transects spanning five habitat types. We generated a dated phylogenetic tree including all sampled taxa to partition the phylogenetic diversity of the nine transects into alpha and beta components at the level of the transects and of the habitat types. The variation in phylogenetic composition among transects did not deviate from a random pattern at the scale of the Dja Faunal Reserve, probably due to a common history and weak environmental variation across the park. This lack of phylogenetic structure combined with an isolation-by-distance pattern of taxonomic diversity suggests that neutral dispersal limitation is a major driver of community assembly in the Dja. To assess any lack of sensitivity to the variation in habitat types, we restricted the analyses of transects to the terra firme primary forest and found results consistent with those of the whole dataset at the level of the transects. Additionally to previous analyses, we detected a weak but significant phylogenetic turnover among habitat types, suggesting that species sort in varying environments, even though it is not predominating on the overall phylogenetic structure. Finer analyses of clades indicated a signal of clustering for species from the Annonaceae family, while species from the Apocynaceae family indicated overdispersion. These results can contribute to the conservation of the park by improving our understanding of the processes dictating community assembly in these hyperdiverse but threatened regions of the world. PMID:24936786

Microbial processes and communities in sediment samples along a transect across the Lusi mud volcano, Indonesia

NASA Astrophysics Data System (ADS)

Krueger, Martin; Straaten, Nontje; Mazzini, Adriano

2015-04-01

The Lusi eruption represents one of the largest ongoing sedimentary hosted geothermal systems. This eruption started in 2006 following to a 6.3 M earthquake that stroke Java Island. Since then it has been spewing boiling mud from a central crater with peaks reaching 180.000 m3 per day. Today an area of about 8 km2 is covered by locally dried mud breccia where a network of hundreds of satellite seeping pools is active. Numerous investigations focused on the study of offshore microbial colonies that commonly thrive at offshore methane seeps and mud volcanoes, however very little has been done for onshore seeping structures. Lusi represents a unique opportunity to complete a comprehensive study of onshore microbial communities fed by the seepage of CH4 and CO2 as well as of heavier liquid hydrocarbons originating from several km below the surface. We conducted a sampling campaign at the Lusi site collecting samples of fresh mud close to the erupting crater using a remote controlled drone. In addition we completed a transect towards outer parts of the crater to collect older, weathered samples for comparison. In all samples active microorganisms were present. The highest activities for CO2 and CH4 production as well as for CH4 oxidation and hydrocarbon degradation were observed in medium-age mud samples collected roughly in the middle of the transect. Rates for aerobic methane oxidation were high, as was the potential of the microbial communities to degrade hydrocarbons (oils, alkanes, BTEX tested). The data suggests a transition of microbial populations from an anaerobic, hydrocarbon-driven metabolism in fresher samples from center or from small seeps to more generalistic, aerobic microbial communities in older, more consolidated sediments. Currently, the microbial communities in the different sediment samples are analyzed using quantitative PCR and T-RFLP combined with MiSeq sequencing. This study represents an initial step to better understand onshore seepage systems and provides an ideal analogue for comparison with the better investigated offshore structures.

Spatial variability in soil organic carbon in a tropical montane landscape: associations between soil organic carbon and land use, soil properties, vegetation, and topography vary across plot to landscape scales

NASA Astrophysics Data System (ADS)

de Blécourt, Marleen; Corre, Marife D.; Paudel, Ekananda; Harrison, Rhett D.; Brumme, Rainer; Veldkamp, Edzo

2017-08-01

Presently, the lack of data on soil organic carbon (SOC) stocks in relation to land-use types and biophysical characteristics prevents reliable estimates of ecosystem carbon stocks in montane landscapes of mainland SE Asia. Our study, conducted in a 10 000 ha landscape in Xishuangbanna, SW China, aimed at assessing the spatial variability in SOC concentrations and stocks, as well as the relationships of SOC with land-use types, soil properties, vegetation characteristics and topographical attributes at three spatial scales: (1) land-use types within a landscape (10 000 ha), (2) sampling plots (1 ha) nested within land-use types (plot distances ranging between 0.5 and 12 km), and (3) subplots (10 m radius) nested within sampling plots. We sampled 27 one-hectare plots - 10 plots in mature forests, 11 plots in regenerating or highly disturbed forests, and 6 plots in open land including tea plantations and grasslands. We used a sampling design with a hierarchical structure. The landscape was first classified according to land-use types. Within each land-use type, sampling plots were randomly selected, and within each plot we sampled within nine subplots. SOC concentrations and stocks did not differ significantly across the four land-use types. However, within the open-land category, SOC concentrations and stocks in grasslands were higher than in tea plantations (P < 0.01 for 0-0.15 m, P = 0.05 for 0.15-0.30 m, P = 0.06 for 0-0.9 m depth). The SOC stocks to a depth of 0.9 m were 177.6 ± 19.6 (SE) Mg C ha-1 in tea plantations, 199.5 ± 14.8 Mg C ha-1 in regenerating or highly disturbed forests, 228.6 ± 19.7 Mg C ha-1 in mature forests, and 236.2 ± 13.7 Mg C ha-1 in grasslands. In this montane landscape, variability within plots accounted for more than 50 % of the overall variance in SOC stocks to a depth of 0.9 m and the topsoil SOC concentrations. The relationships of SOC concentrations and stocks with land-use types, soil properties, vegetation characteristics, and topographical attributes varied across spatial scales. Variability in SOC within plots was determined by litter layer carbon stocks (P < 0.01 for 0-0.15 m and P = 0.03 for 0.15-0.30 and 0-0.9 m depth) and slope (P ≤ 0.01 for 0-0.15, 0.15-0.30, and 0-0.9 m depth) in open land, and by litter layer carbon stocks (P < 0.001 for 0-0.15, 0.15-0.30 and 0-0.9 m depth) and tree basal area (P < 0.001 for 0-0.15 m and P = 0.01 for 0-0.9 m depth) in forests. Variability in SOC among plots in open land was related to the differences in SOC concentrations and stocks between grasslands and tea plantations. In forests, the variability in SOC among plots was associated with elevation (P < 0.01 for 0-0.15 m and P = 0.09 for 0-0.9 m depth). The scale-dependent relationships between SOC and its controlling factors demonstrate that studies that aim to investigate the land-use effects on SOC need an appropriate sampling design reflecting the controlling factors of SOC so that land-use effects will not be masked by the variability between and within sampling plots.

Split-plot microarray experiments: issues of design, power and sample size.

PubMed

Tsai, Pi-Wen; Lee, Mei-Ling Ting

2005-01-01

This article focuses on microarray experiments with two or more factors in which treatment combinations of the factors corresponding to the samples paired together onto arrays are not completely random. A main effect of one (or more) factor(s) is confounded with arrays (the experimental blocks). This is called a split-plot microarray experiment. We utilise an analysis of variance (ANOVA) model to assess differentially expressed genes for between-array and within-array comparisons that are generic under a split-plot microarray experiment. Instead of standard t- or F-test statistics that rely on mean square errors of the ANOVA model, we use a robust method, referred to as 'a pooled percentile estimator', to identify genes that are differentially expressed across different treatment conditions. We illustrate the design and analysis of split-plot microarray experiments based on a case application described by Jin et al. A brief discussion of power and sample size for split-plot microarray experiments is also presented.

Effects of Eriophorum vaginatum on N_{2}O emissions at a restored peatland

NASA Astrophysics Data System (ADS)

Brummell, Martin; Lazcano, Cristina; Strack, Maria

2016-04-01

Restoration of peatlands extracted for horticultural peat production includes both deliberate and accidental introduction of a wide range of plant species, including vascular plants and bryophytes. The roots of vascular plants provide a channel for the movement of greenhouse gases (GHG) including N2O in many soil ecosystems, and may stimulate production of N2O or have other effects via the release of root exudates that are then taken up by soil microorganisms such as heterotrophic denitrifiers. Here we carried out a field study in order to evaluate the effects of Eriophorum vaginatum, an abundant sedge at the harvested peatland at Seba Beach, Alberta, Canada, (53° 27'17.2"N 114° 52'52.0"W) where restoration efforts began in late 2012, and is the dominant ground cover in some areas. We hypothesized that E. vaginatum would increase net N2O production from peat compared to areas of bare peat or moss. We measured net GHG exchange for CO2, CH4, and N2O over one growing season (May-September 2015) using static chambers within this peatland to compare between plots containing E. vaginatum and plots lacking vascular plants. Plots were located along a transect of increasing water table, in order to discriminate between the effects of E. vaginatum and the prevailing hydrological conditions on N2O fluxes. Net fluxes of N2O from the peat to the atmosphere were observed throughout the experimental area, as well as fluxes in the opposite direction, in which the peat removed N2O from the atmosphere inside the chamber. Non-zero fluxes were highly variable in both occurrence and magnitude, though a small number of plots accounted for the majority of measured fluxes. Neither aboveground biomass of E. vaginatum nor its presence in a plot was correlated with either frequency or direction of N2O flux measurements. Other factors, such as water table fluctuations and temperature may be stronger drivers of these microbially-mediated processes than vegetation at this stage of the restoration.

Effects of tree-to-tree variations on sap flux-based transpiration estimates in a forested watershed

NASA Astrophysics Data System (ADS)

Kume, Tomonori; Tsuruta, Kenji; Komatsu, Hikaru; Kumagai, Tomo'omi; Higashi, Naoko; Shinohara, Yoshinori; Otsuki, Kyoichi

2010-05-01

To estimate forest stand-scale water use, we assessed how sample sizes affect confidence of stand-scale transpiration (E) estimates calculated from sap flux (Fd) and sapwood area (AS_tree) measurements of individual trees. In a Japanese cypress plantation, we measured Fd and AS_tree in all trees (n = 58) within a 20 × 20 m study plot, which was divided into four 10 × 10 subplots. We calculated E from stand AS_tree (AS_stand) and mean stand Fd (JS) values. Using Monte Carlo analyses, we examined potential errors associated with sample sizes in E, AS_stand, and JS by using the original AS_tree and Fd data sets. Consequently, we defined optimal sample sizes of 10 and 15 for AS_stand and JS estimates, respectively, in the 20 × 20 m plot. Sample sizes greater than the optimal sample sizes did not decrease potential errors. The optimal sample sizes for JS changed according to plot size (e.g., 10 × 10 m and 10 × 20 m), while the optimal sample sizes for AS_stand did not. As well, the optimal sample sizes for JS did not change in different vapor pressure deficit conditions. In terms of E estimates, these results suggest that the tree-to-tree variations in Fd vary among different plots, and that plot size to capture tree-to-tree variations in Fd is an important factor. This study also discusses planning balanced sampling designs to extrapolate stand-scale estimates to catchment-scale estimates.

Elevation-dependent changes in n-alkane δD and soil GDGTs across the South Central Andes

NASA Astrophysics Data System (ADS)

Nieto-Moreno, Vanesa; Rohrmann, Alexander; van der Meer, Marcel T. J.; Sinninghe Damsté, Jaap S.; Sachse, Dirk; Tofelde, Stefanie; Niedermeyer, Eva M.; Strecker, Manfred R.; Mulch, Andreas

2016-11-01

Surface uplift of large plateaus may significantly influence regional climate and more specifically precipitation patterns and temperature, sometimes complicating paleoaltimetry interpretations. Thus, understanding the topographic evolution of tectonically active mountain belts benefits from continued development of reliable proxies to reduce uncertainties in paleoaltimetry reconstructions. Lipid biomarker-based proxies provide a novel approach to stable isotope paleoaltimetry and complement authigenic or pedogenic mineral proxy materials, in particular outside semi-arid climate zones where soil carbonates are not abundant but (soil) organic matter has a high preservation potential. Here we present δD values of soil-derived n-alkanes and mean annual air temperature (MAT) estimates based on branched glycerol dialkyl glycerol tetraether (brGDGT) distributions to assess their potential for paleoelevation reconstructions in the southern central Andes. We analyzed soil samples across two environmental and hydrological gradients that include a hillslope (26-28°S) and a valley (22-24°S) transect on the windward flanks of Central Andean Eastern Cordillera in NW Argentina. Our results show that present-day n-alkane δD values and brGDGT-based MAT estimates are both linearly related with elevation and in good agreement with present-day climate conditions. Soil n-alkanes show a δD lapse rate (Δ (δD)) of - 1.64 ‰ / 100 m (R2 = 0.91, p < 0.01) at the hillslope transect, within the range of δD lapse rates from precipitation and surface waters in other tropical regions in the Andes like the Eastern Cordillera in Colombia and Bolivia and the Equatorial and Peruvian Andes. BrGDGT-derived soil temperatures are similar to monitored winter temperatures in the region and show a lapse rate of ΔT = - 0.51 °C / 100 m (R2 = 0.91, p < 0.01), comparable with lapse rates from in situ soil temperature measurements, satellite-derived land-surface temperatures at this transect, and weather stations from the Eastern Cordillera at similar latitude. As a result of an increasing leeward sampling position along the valley transect lapse rates are biased towards lower values and display higher scatter (Δ (δD) = - 0.95 ‰ / 100 m, R2 = 0.76, p < 0.01 and ΔT = - 0.19 °C / 100 m, R2 = 0.48, p < 0.05). Despite this higher complexity, they are in line with lapse rates from stream-water samples and in situ soil temperature measurements along the same transect. Our results demonstrate that both soil n-alkane δD values and MAT reconstructions based on brGDGTs distributions from the hillslope transect (Δ (δD) = - 1.64 ‰ / 100 m, R2 = 0.91, p < 0.01 and ΔT = - 0.51 °C / 100 m, R2 = 0.91, p < 0.01) track the direct effects of orography on precipitation and temperature and hence the combined effects of local and regional hydrology as well as elevation.

Sequential sampling of ribes populations in the control of white pine blister rust (Cronartium ribicola Fischer) in California

Treesearch

Harold R. Offord

1966-01-01

Sequential sampling based on a negative binomial distribution of ribes populations required less than half the time taken by regular systematic line transect sampling in a comparison test. It gave the same control decision as the regular method in 9 of 13 field trials. A computer program that permits sequential plans to be built readily for other white pine regions is...

Variation in biotic assemblages and stream-habitat data with sampling strategy and method in tidal segments of Highland and Marchand Bayous, Galveston County, Texas, 2007

USGS Publications Warehouse

Mabe, Jeffrey A.; Moring, J. Bruce

2008-01-01

The U.S. Geological Survey, in cooperation with the Houston-Galveston Area Council and the Galveston Bay Estuary Program under the authority of the Texas Commission on Environmental Quality, did a study in 2007 to assess the variation in biotic assemblages (benthic macroinvertebrate and fish communities) and stream-habitat data with sampling strategy and method in tidal segments of Highland Bayou and Marchand Bayou in Galveston County. Data were collected once in spring and once in summer 2007 from four stream sites (reaches) (short names Hitchcock, Fairwood, Bayou Dr, and Texas City) of Highland Bayou and from one reach (short name Marchand) in Marchand Bayou. Only stream-habitat data from summer 2007 samples were used for this report. Additional samples were collected at the Hitchcock, Fairwood, and Bayou Dr reaches (multisample reaches) during summer 2007 to evaluate variation resulting from sampling intensity and location. Graphical analysis of benthic macroinvertebrate community data using a multidimensional scaling technique indicates there are taxonomic differences between the spring and summer samples. Seasonal differences in communities primarily were related to decreases in the abundance of chironomids and polychaetes in summer samples. Multivariate Analysis of Similarities tests of additional summer 2007 benthic macroinvertebrate samples from Hitchcock, Fairwood, and Bayou Dr indicated significant taxonomic differences between the sampling locations at all three reaches. In general, the deepwater samples had the smallest numbers for benthic macroinvertebrate taxa richness and abundance. Graphical analysis of species-level fish data indicates no consistent seasonal difference in fish taxa across reaches. Increased seining intensity at the multisample reaches did not result in a statistically significant difference in fish communities. Increased seining resulted in some changes in taxa richness and community diversity metrics. Diversity increases associated with increased electrofishing intensity were relatively consistent across the two multisample electrofishing reaches (Hitchcock and Fairwood). Differences in the physical characteristics of the Highland and Marchand Bayou reaches are largely the result of the differences in channel gradient and position in the drainage network or watershed of each reach. No trees were observed on the bank adjacent to the five transects at either the Bayou Dr or Texas City reaches. Riparian vegetation at the more downstream Fairwood, Bayou Dr, and Texas City reaches was dominated by less-woody and more-herbaceous shrubs, and grasses and forbs, than at the more upstream Hitchcock and Marchand reaches. The width of the vegetation buffer was variable among all reaches and appeared to be more related to the extent of anthropogenic development in the riparian zone rather than to natural changes in the riparian buffer. Four additional transects per reach were sampled for habitat variables at Hitchcock, Fairwood, and Bayou Dr. Medians of most stream-habitat variables changed with increased sampling intensity (addition of two and four transects to the standard five transects), although none of the differences in medians were statistically significant. All habitat quality index values for the five reaches scored in the intermediate category. Increasing sampling intensity did not change the habitat quality index score for any of the reaches.

Spectral reflectance patterns and temporal dynamics of common understory types in hemi-boreal forests in Järvselja, Estonia

NASA Astrophysics Data System (ADS)

Nikopensius, Maris; Raabe, Kairi; Pisek, Jan

2014-05-01

The knowledge about spectral properties and seasonal dynamics of understory layers in boreal forests currently holds several gaps. This introduces severe uncertainties while modelling the carbon balance of this ecosystem, which is expected to be prone to major shifts with climate change in the future. In this work the seasonal reflectance dynamics in European hemi-boreal forests are studied. The data for this study was collected at Järvselja Training and Experimental Forestry District (Estonia, 27.26°E 58.30°N). Measurements were taken in three different stands. The silver birch (Betula Pendula Roth) stand grows on typical brown gley-soil and its understory vegetation is dominated by a mixture of several grass species. The Scots pine (Pinus sylvestris) stand grows on a bog with understory vegetation composed of sparse labrador tea, cotton grass, and a continuous Sphagnum moss layer. The third stand, Norway spruce (Picea abies), grows on a Gleyi Ferric Podzol site with understory vegetation either partially missing or consisting of mosses such as Hylocomium splendens or Pleurozium schreberi [1]. The sampling design was similar to the study by Rautiainen et al. [3] in northern European boreal forests. At each study site, a 100 m long permanent transect was marked with flags. In addition, four intensive study plots (1 m × 1 m) were marked next to the transects at 20 m intervals. The field campaign lasted from May to September 2013. For each site the fractional cover of understory and understory spectra were estimated ten times i.e. every 2 to 3 weeks. Results from Järvselja forest were compared with the seasonal profiles from boreal forests in Hyytiälä, Finland [2]. References [1] A. Kuusk, M. Lang, J. Kuusk, T. Lükk, T. Nilson, M. Mõttus, M. Rautiainen, and A. Eenmäe, "Database of optical and structural data for validation of radiative transfer models", Technical Report, September 2009 [2] M. Rautiainen, M. Mõttus, J. Heiskanen, A. Akujärvi, T. Majasalmi, P. Stenberg, "Seasonal reflectance dynamics of common understory types in a northern Europe boreal forest," Remote Sensing of Environment, vol. 115, pp. 3020-3028, July 2011

Geochemical gradients in soil O-horizon samples from southern Norway: Natural or anthropogenic?

USGS Publications Warehouse

Reimann, C.; Englmaier, P.; Flem, B.; Gough, L.; Lamothe, P.; Nordgulen, O.; Smith, D.

2009-01-01

Forty soil O- and C-horizon samples were collected along a south-to-north transect extending inland for approximately 200 km from the southern tip of Norway. The elements As, Au, Bi, Cd, Cu, Ga, Ge, Hf, Hg, In, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, V, W, Zn and Zr all show a distinct decrease in concentration in soil O-horizons with increasing distance from the coast. The elements showing the strongest coastal enrichment, some by more than an order of magnitude compared to inland samples, are Au, Bi, As, Pb, Sb and Sn. Furthermore, the elements Cd (median O-/median C-horizon = 31), C, Sb, Ag, K, S, Ge (10), Hg, Pb, As, Bi, Sr (5), Se, Au, Ba, Na, Zn, P, Cu and Sn (2) are all strongly enriched in the O-horizon when compared to the underlying C-horizon. Lead isotope ratios, however, do not show any gradient with distance from the coast (declining Pb concentration). Along a 50 km topographically steep east-west transect in the centre of the survey area, far from the coast but crossing several vegetation zones, similar element enrichment patterns and concentration gradients can be observed in the O-horizon. Lead isotope ratios in the O-horizon correlate along both transects with pH and the C/N-ratio, both proxies for the quality of the organic material. Natural conditions in southern Norway, related to climate and vegetation, rather than long range atmospheric transport of air pollutants (LRT), cause the observed features. ?? 2008 Elsevier Ltd.

Effects of Canals and Roads on Hydrologic Conditions and Health of Atlantic White Cedar at Emily and Richardson Preyer Buckridge Coastal Reserve, North Carolina, 2003-2006

USGS Publications Warehouse

Ferrell, Gloria M.; Strickland, A. Gerald; Spruill, Timothy B.

2007-01-01

The effects of canals and roads on hydrologic conditions and on the health of Atlantic white cedar at the Emily and Richardson Preyer Buckridge Coastal Reserve in North Carolina were evaluated by using data collected from the 1980s to 2006. Water levels were monitored along two transects established perpendicular to roads and canals in areas of healthy and unhealthy Atlantic white cedar as part of a study conducted from February 2003 through March 2006. Because of the low hydraulic gradient at the Reserve, the rate and direction of water movement are sensitive to disturbance. Canals increased drainage and contributed to lower water levels in some parts of the Reserve, whereas roads, depending on orientation, impeded drainage. Canals also appeared to facilitate movement of brackish water from the Alligator River into the interior of the Reserve during storms and wind tides. Data indicate that an influx of brackish water occurred in mid-September 2005 several days after the passage of Hurricane Ophelia. Although precipitation amounts and wind speeds associated with Hurricane Ophelia were not large, substantial changes in specific conductance occurred at the canal site on the unhealthy Atlantic white cedar transect. No corresponding increase in specific conductance was observed at the canal site on the healthy Atlantic white cedar transect. The specific conductance of water samples from canals and piezometers was highly correlated with concentrations of chloride and sodium. Ion ratios of some of the water samples, particularly samples with high specific conductance, were similar to those of seawater. Thermal and chemical stratification of water in the canals occurred during summer and winter months, and turnover and mixing occurred in the spring and fall. Upwelling of ground water as a result of excavation for roads did not appear to have a significant effect on the water quality of samples from the canals or piezometers. The specific conductance of water samples from piezometers installed in the root zone of healthy stands of Atlantic white cedar generally was lower than in water samples from unhealthy stands. This pattern also was observed in samples from piezometers installed on the transects and in other areas of the Reserve. Roads appear to have isolated some areas of the Reserve from the high-conductivity water in nearby canals. The paths by which brackish water entered the Reserve cannot be determined from the data obtained during this investigation. It appears that water can enter the Reserve from various directions, depending on wind patterns and water levels in the Alligator River.

A sampling plan for riparian birds of the Lower Colorado River-Final Report

USGS Publications Warehouse

Bart, Jonathan; Dunn, Leah; Leist, Amy

2010-01-01

A sampling plan was designed for the Bureau of Reclamation for selected riparian birds occurring along the Colorado River from Lake Mead to the southerly International Boundary with Mexico. The goals of the sampling plan were to estimate long-term trends in abundance and investigate habitat relationships especially in new habitat being created by the Bureau of Reclamation. The initial objective was to design a plan for the Gila Woodpecker (Melanerpes uropygialis), Arizona Bell's Vireo (Vireo bellii arizonae), Sonoran Yellow Warbler (Dendroica petechia sonorana), Summer Tanager (Piranga rubra), Gilded Flicker (Colaptes chrysoides), and Vermilion Flycatcher (Pyrocephalus rubinus); however, too little data were obtained for the last two species. Recommendations were therefore based on results for the first four species. The study area was partitioned into plots of 7 to 23 hectares. Plot borders were drawn to place the best habitat for the focal species in the smallest number of plots so that survey efforts could be concentrated on these habitats. Double sampling was used in the survey. In this design, a large sample of plots is surveyed a single time, yielding estimates of unknown accuracy, and a subsample is surveyed intensively to obtain accurate estimates. The subsample is used to estimate detection ratios, which are then applied to the results from the extensive survey to obtain unbiased estimates of density and population size. These estimates are then used to estimate long-term trends in abundance. Four sampling plans for selecting plots were evaluated based on a simulation using data from the Breeding Bird Survey. The design with the highest power involved selecting new plots every year. Power with 80 plots surveyed per year was more than 80 percent for three of the four species. Results from the surveys were used to provide recommendations to the Bureau of Reclamation for their surveys of new habitat being created in the study area.

Double sampling to estimate density and population trends in birds

USGS Publications Warehouse

Bart, Jonathan; Earnst, Susan L.

2002-01-01

We present a method for estimating density of nesting birds based on double sampling. The approach involves surveying a large sample of plots using a rapid method such as uncorrected point counts, variable circular plot counts, or the recently suggested double-observer method. A subsample of those plots is also surveyed using intensive methods to determine actual density. The ratio of the mean count on those plots (using the rapid method) to the mean actual density (as determined by the intensive searches) is used to adjust results from the rapid method. The approach works well when results from the rapid method are highly correlated with actual density. We illustrate the method with three years of shorebird surveys from the tundra in northern Alaska. In the rapid method, surveyors covered ~10 ha h-1 and surveyed each plot a single time. The intensive surveys involved three thorough searches, required ~3 h ha-1, and took 20% of the study effort. Surveyors using the rapid method detected an average of 79% of birds present. That detection ratio was used to convert the index obtained in the rapid method into an essentially unbiased estimate of density. Trends estimated from several years of data would also be essentially unbiased. Other advantages of double sampling are that (1) the rapid method can be changed as new methods become available, (2) domains can be compared even if detection rates differ, (3) total population size can be estimated, and (4) valuable ancillary information (e.g. nest success) can be obtained on intensive plots with little additional effort. We suggest that double sampling be used to test the assumption that rapid methods, such as variable circular plot and double-observer methods, yield density estimates that are essentially unbiased. The feasibility of implementing double sampling in a range of habitats needs to be evaluated.

PHLUX: Photographic Flux Tools for Solar Glare and Flux

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

2010-12-02

A web-based tool to a) analytically and empirically quantify glare from reflected light and determine the potential impact (e.g., temporary flash blindness, retinal burn), and b) produce flux maps for central receivers. The tool accepts RAW digital photographs of the glare source (for hazard assessment) or the receiver (for flux mapping), as well as a photograph of the sun for intensity and size scaling. For glare hazard assessment, the tool determines the retinal irradiance (W/cm2) and subtended source angle for an observer and plots the glare source on a hazard spectrum (i.e., low-potential for flash blindness impact, potential for flashmore » blindness impact, retinal burn). For flux mapping, the tool provides a colored map of the receiver scaled by incident solar flux (W/m2) and unwraps the physical dimensions of the receiver while accounting for the perspective of the photographer (e.g., for a flux map of a cylindrical receiver, the horizontal axis denotes receiver angle in degrees and the vertical axis denotes vertical position in meters; for a flat panel receiver, the horizontal axis denotes horizontal position in meters and the vertical axis denotes vertical position in meters). The flux mapping capability also allows the user to specify transects along which the program plots incident solar flux on the receiver.« less

Population ecology of the gulf ribbed mussel across a salinity gradient: recruitment, growth and density

USGS Publications Warehouse

Honig, Aaron; Supan, John; LaPeyre, Megan K.

2015-01-01

Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences. Recruitment, growth, mortality, population size structure and density of the gulf coast ribbed mussel, Geukensia granosissima, were examined across a salinity gradient in southeastern Louisiana. Data were collected along 100-m transects at interior and edge marsh plots located at duplicate sites in upper (salinity ~4 psu), central (salinity ~8 psu) and lower (salinity ~15 psu) Barataria Bay, Louisiana, U.S.A. Growth, mortality and recruitment were measured in established plots from April through November 2012. Mussel densities were greatest within the middle bay (salinity ~8) regardless of flooding regime, but strongly associated with highest stem densities of Juncus roemerianus vegetation. Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior marsh and low salinity sites. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability, host vegetation community distribution along the salinity gradient, salinity tolerance of the mussel, and reduced predation at higher salinity edge sites.

Modeling grain size variations of aeolian gypsum deposits at White Sands, New Mexico, using AVIRIS imagery

USGS Publications Warehouse

Ghrefat, H.A.; Goodell, P.C.; Hubbard, B.E.; Langford, R.P.; Aldouri, R.E.

2007-01-01

Visible and Near-Infrared (VNIR) through Short Wavelength Infrared (SWIR) (0.4-2.5????m) AVIRIS data, along with laboratory spectral measurements and analyses of field samples, were used to characterize grain size variations in aeolian gypsum deposits across barchan-transverse, parabolic, and barchan dunes at White Sands, New Mexico, USA. All field samples contained a mineralogy of ?????100% gypsum. In order to document grain size variations at White Sands, surficial gypsum samples were collected along three Transects parallel to the prevailing downwind direction. Grain size analyses were carried out on the samples by sieving them into seven size fractions ranging from 45 to 621????m, which were subjected to spectral measurements. Absorption band depths of the size fractions were determined after applying an automated continuum-removal procedure to each spectrum. Then, the relationship between absorption band depth and gypsum size fraction was established using a linear regression. Three software processing steps were carried out to measure the grain size variations of gypsum in the Dune Area using AVIRIS data. AVIRIS mapping results, field work and laboratory analysis all show that the interdune areas have lower absorption band depth values and consist of finer grained gypsum deposits. In contrast, the dune crest areas have higher absorption band depth values and consist of coarser grained gypsum deposits. Based on laboratory estimates, a representative barchan-transverse dune (Transect 1) has a mean grain size of 1.16 ??{symbol} (449????m). The error bar results show that the error ranges from - 50 to + 50????m. Mean grain size for a representative parabolic dune (Transect 2) is 1.51 ??{symbol} (352????m), and 1.52 ??{symbol} (347????m) for a representative barchan dune (Transect 3). T-test results confirm that there are differences in the grain size distributions between barchan and parabolic dunes and between interdune and dune crest areas. The t-test results also show that there are no significant differences between modeled and laboratory-measured grain size values. Hyperspectral grain size modeling can help to determine dynamic processes shaping the formation of the dunes such as wind directions, and the relative strengths of winds through time. This has implications for studying such processes on other planetary landforms that have mineralogy with unique absorption bands in VNIR-SWIR hyperspectral data. ?? 2006 Elsevier B.V. All rights reserved.

The effects of landscape position on plant species density: Evidence of past environmental effects in a coastal wetland

USGS Publications Warehouse

Grace, J.B.; Guntenspergen, G.R.

1999-01-01

Here we propose that an important cause of variation in species density may be prior environmental conditions that continue to influence current patterns. In this paper we investigated the degree to which species density varies with location within the landscape, independent of contemporaneous environmental conditions. The area studied was a coastal marsh landscape subject to periodic storm events. To evaluate the impact of historical effects, it was assumed that the landscape position of a plot relative to the river's mouth ('distance from sea') and to the edge of a stream channel ('distance from shore') would correlate with the impact of prior storm events, an assumption supported by previous studies. To evaluate the importance of spatial location on species density, data were collected from five sites located at increasing distances from the river's mouth along the Middle Pearl River in Louisiana. At each site, plots were established systematically along transects perpendicular to the shoreline. For each of the 175 Plots, we measured elevation, soil salinity, percent of plot recently disturbed, percent of sunlight captured by the plant canopy (as a measure of plant abundance), and plant species density. Structural equation analysis ascertained the degree to which landscape position variables explained variation in species density that could not be explained by current environmental indicators. Without considering landscape variables, 54% of the variation in species density could be explained by the effects of salinity, flooding, and plant abundance. When landscape variables were included, distance from shore was unimportant but distance from sea explained an additional 12% of the variance in species density (R2 of final model = 66%). Based on these results it appears that at least some of the otherwise unexplained variation in species density can be attributed to landscape position, and presumably previous storm events. We suggest that future studies may gain additional insight into the factors controlling current patterns of species density by examining the effects of position within the landscape.

Detection and monitoring of invasive exotic plants: a comparison of four sampling methods

Treesearch

Cynthia D. Huebner

2007-01-01

The ability to detect and monitor exotic invasive plants is likely to vary depending on the sampling method employed. Methods with strong qualitative thoroughness for species detection often lack the intensity necessary to monitor vegetation change. Four sampling methods (systematic plot, stratified-random plot, modified Whittaker, and timed meander) in hemlock and red...

Development of a Long-term Sampling Network to Monitor Restoration Success in the Southwest Coastal Everglades: Vegetation, Hydrology, and Sediments

USGS Publications Warehouse

Smith, Thomas J.

2004-01-01

Introduction and History Hurricane Andrew, a Category 5 storm, crossed the southern Florida peninsula on the morning of August 24, 1992 (Fig. 1). Following the storm, the National Park Service conducted an environmental damage assessment to gauge the storm's impacts on the natural resources of south Florida Park Service holdings (Pimm et al., 1994). Although hurricanes have impacted Park Service lands such as the Everglades in the past (Houston and Powell, 2003), no systematic, permanent sampling scheme has been established to monitor long-term recovery (or lack thereof) following disturbance. In October 1992, vegetation monitoring plots were established in heavily damaged areas of mangrove forest on the southwest coast of the Everlgades, along the Lostmans and Broad Rivers (Smith et al., 1994, see Fig. 2). As the permanent plot network was being established, funding was awarded for the South Florida Global Climate Change project (SOFL-GCC). This led to the establishment of a network of hydrological monitoring stations (Anderson and Smith, 2004). Finally, sediment elevation tables (SETs) were installed at many locations. SETs provide the means to measure very small changes (2 mm) in the sediment surface elevation accurately over time (Cahoon et al., 2002). We also set up marker horizons to measure accretion of sediment at each site (Smith and Cahoon, 2003). Sampling sites were located along three transects extending from upstream freshwater wetlands to downstream saltwater wetlands along the Shark, Lostmans and Chatham Rivers in Everglades National Park (Fig. 2). While we were developing our sampling network for basic scientific research needs, concern mounted over the health of the Greater Everglades Ecosystem and in particular over the influence of decreased freshwater flows (Smith et al., 1989). Ecosystem restoration planning was begun, resulting in the multi-agency, $8 billion Comprehensive Everglades Restoration Plan (CERP). Our co-located sampling networks Fig. 3) allow us to track the interaction of hydrology, sediment, and vegetation over time, and will provide the opportunity to monitor the progress of the Everglades restoration and to gauge its success. Our earlier research questions have been modified over time to place a major emphasis on CERP needs, while still recognizing the importance of other processes, including disturbance and sea-level rise. Our research addresses processes relevant to the following restoration and related questions: * How will increasing freshwater flow affect wetland primary production? * Will increasing freshwater inflow alter nutrient availability? * Does recovery following disturbance in mangroves depend on freshwater inflow? * Will the position of vegetation ecotones change in response to upstream water management? * What will be the influence of global climate change, such as sea-level rise, on the Everglades restoration? * Will processes of wetlands soil formation be altered by sea-level rise and changed freshwater inflow?

A new method for estimating the demographic history from DNA sequences: an importance sampling approach

PubMed Central

Ait Kaci Azzou, Sadoune; Larribe, Fabrice; Froda, Sorana

2015-01-01

The effective population size over time (demographic history) can be retraced from a sample of contemporary DNA sequences. In this paper, we propose a novel methodology based on importance sampling (IS) for exploring such demographic histories. Our starting point is the generalized skyline plot with the main difference being that our procedure, skywis plot, uses a large number of genealogies. The information provided by these genealogies is combined according to the IS weights. Thus, we compute a weighted average of the effective population sizes on specific time intervals (epochs), where the genealogies that agree more with the data are given more weight. We illustrate by a simulation study that the skywis plot correctly reconstructs the recent demographic history under the scenarios most commonly considered in the literature. In particular, our method can capture a change point in the effective population size, and its overall performance is comparable with the one of the bayesian skyline plot. We also introduce the case of serially sampled sequences and illustrate that it is possible to improve the performance of the skywis plot in the case of an exponential expansion of the effective population size. PMID:26300910

Mercury distribution and transport in the North Atlantic Ocean along the GEOTRACES-GA01 transect

NASA Astrophysics Data System (ADS)

Cossa, Daniel; Heimbürger, Lars-Eric; Pérez, Fiz F.; García-Ibáñez, Maribel I.; Sonke, Jeroen E.; Planquette, Hélène; Lherminier, Pascale; Boutorh, Julia; Cheize, Marie; Lukas Menzel Barraqueta, Jan; Shelley, Rachel; Sarthou, Géraldine

2018-04-01

We report here the results of total mercury (HgT) determinations along the 2014 Geotraces Geovide cruise (GA01 transect) in the North Atlantic Ocean (NA) from Lisbon (Portugal) to the coast of Labrador (Canada). HgT concentrations in unfiltered samples (HgTUNF) were log-normally distributed and ranged between 0.16 and 1.54 pmol L-1, with a geometric mean of 0.51 pmol L-1 for the 535 samples analysed. The dissolved fraction (< 0.45 µm) of HgT (HgTF), determined on 141 samples, averaged 78 % of the HgTUNF for the entire data set, 84 % for open seawaters (below 100 m) and 91 % if the Labrador Sea data are excluded, where the primary production was high (with a winter convection down to 1400 m). HgTUNF concentrations increased eastwards and with depth from Greenland to Europe and from subsurface to bottom waters. The HgTUNF concentrations were similarly low in the subpolar gyre waters ( ˜ 0.45 pmol L-1), whereas they exceeded 0.60 pmol L-1 in the subtropical gyre waters. The HgTUNF distribution mirrored that of dissolved oxygen concentration, with highest concentration levels associated with oxygen-depleted zones. The relationship between HgTF and the apparent oxygen utilization confirms the nutrient-like behaviour of Hg in the NA. An extended optimum multiparameter analysis allowed us to characterize HgTUNF concentrations in the different source water types (SWTs) present along the transect. The distribution pattern of HgTUNF, modelled by the mixing of SWTs, show Hg enrichment in Mediterranean waters and North East Atlantic Deep Water and low concentrations in young waters formed in the subpolar gyre and Nordic seas. The change in anthropogenic Hg concentrations in the Labrador Sea Water during its eastward journey suggests a continuous decrease in Hg content in this water mass over the last decades. Calculation of the water transport driven by the Atlantic Meridional Overturning Circulation across the Portugal-Greenland transect indicates northward Hg transport within the upper limb and southward Hg transport within the lower limb, with resulting net northward transport of about 97.2 kmol yr-1.

Farms, pastures and woodlands: the fine-scale distribution of Palearctic Culicoides spp. biting midges along an agro-ecological gradient.

PubMed

Rigot, T; Drubbel, M Vercauteren; Delécolle, J-C; Gilbert, M

2013-03-01

The spatial epidemiology of Bluetongue virus (BTV) at the landscape level relates to the fine-scale distribution and dispersal capacities of its vectors, midges belonging to the genus Culicoides Latreille (Diptera: Ceratopogonidae). Although many previous researches have carried out Culicoides sampling on farms, little is known of the fine-scale distribution of Culicoides in the landscape immediately surrounding farms. The aim of this study was to gain a better understanding of Culicoides populations at increasing distances from typical dairy farms in north-west Europe, through the use of eight Onderstepoort-type black-light traps positioned along linear transects departing from farms, going through pastures and entering woodlands. A total of 16 902 Culicoides were collected in autumn 2008 and spring 2009. The majority were females, of which more than 97% were recognized as potential vectors. In pastures, we found decreasing numbers of female Culicoides as a function of the distance to the farm. This pattern was modelled by leptokurtic models, with parameters depending on season and species. By contrast, the low number of male Culicoides caught were homogeneously distributed along the transects. When transects entered woodlands, we found a higher abundance of Culicoides than expected considering the distance of the sampling sites to the farm, although this varied according to species. © 2012 The Authors. Medical and Veterinary Entomology © 2012 The Royal Entomological Society.

Evaluation of aerial transects for counting winter mallards

USGS Publications Warehouse

Reinecke, K.J.; Brown, M.W.; Nassar, J.R.

1992-01-01

Winter waterfowl surveys rarely use sampling methods, and little is known about the precision and biases of their population estimates. Consequently, we developed aerial transect surveys (n=5) in 4 strata comprising 16 substrata in the lower Mississippi Alluvial Valley during winters 1987-88 through 1989-90 to estimate mallard (Anas platyrhynchos) population indices and determine regional patterns of habitat use. Mallard population indices ranged from 1,147,628 (SE=192,341) in December 1988 to 1,790,708 (SE=179,406) in January 1988. Coefficients of variation (CV's) for early winter surveys averaged 0.15 and those for late winter surveys averaged 0.10. During early winter, 59-69% of mallards were on wetlands with water regimes managed for waterfowl; whereas in late winter, 52-79% used wetlands with unmanaged water regimes. Late winter was wet during 1987-88 and 1988-89, and most mallards (62-68%) were on naturally flooded croplands. Use of forested wetlands (3-11%) and moist-soil habitats (3-29%) varied among surveys but was not correlated with water conditions. The number of mallards using naturally flooded croplands (e.g., >1,100,000 in Jan 1988) illustrated the extent of habitat use on private lands. We recommend transect surveys (e.g., 5-yr intervals) for evaluating responses of mallard populations to management programs and as a sampling framework for integrating regional waterfowl research and management data.

Temporal Dynamics and Spatial Variation of Azoxystrobin and Propiconazole Resistance in Zymoseptoria tritici: A Hierarchical Survey of Commercial Winter Wheat Fields in the Willamette Valley, Oregon.

PubMed

Hagerty, Christina H; Anderson, Nicole P; Mundt, Christopher C

2017-03-01

Fungicide resistance can cause disease control failure in agricultural systems, and is particularly concerning with Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat. In North America, the first quinone outside inhibitor resistance in Z. tritici was discovered in the Willamette Valley of Oregon in 2012, which prompted this hierarchical survey of commercial winter wheat fields to monitor azoxystrobin- and propiconazole-resistant Z. tritici. Surveys were conducted in June 2014, January 2015, May 2015, and January 2016. The survey was organized in a hierarchical scheme: regions within the Willamette Valley, fields within the region, transects within the field, and samples within the transect. Overall, frequency of azoxystrobin-resistant isolates increased from 63 to 93% from June 2014 to January 2016. Resistance to azoxystrobin increased over time even within fields receiving no strobilurin applications. Propiconazole sensitivity varied over the course of the study but, overall, did not significantly change. Sensitivity to both fungicides showed no regional aggregation within the Willamette Valley. Greater than 80% of spatial variation in fungicide sensitivity was at the smallest hierarchical scale (within the transect) of the survey for both fungicides, and the resistance phenotypes were randomly distributed within sampled fields. Results suggest a need for a better understanding of the dynamics of fungicide resistance at the landscape level.

Chemical element concentrations in four lichens on a transect entering Voyageurs National Park

USGS Publications Warehouse

Bennett, J.; Wetmore, C.M.

1997-01-01

A three factor transect study was conducted to test the hypothesis that chemical elements from air emissions in the vicinity of International Falls, Minnesota could not be detected in lichens along a 24 km transect reaching into Voyageurs National Park. It was hypothesized that element concentrations in lichens would decline exponentially downwind and would reach background values at a distance before the park boundary. Four species (Cladina rangiferina, Evernia mesomorpha, Hypogymnia physodes, and Parmelia sulcata) were sampled at ten sites for 3 years and 17 chemical elements were measured. The most notable result was a curvilinear geographic trend for many elements, which decreased from International Falls and then increased towards the park. This trend was significant for many anthropogenic elements, including S, Hg, Cd, and Cr, and for all four species. This type of distribution pattern has been observed in Hypogymnia physodes in other studies downwind of a steel mill and an oil refinery. Cladina, a ground-dwelling lichen, generally had lower tissue concentrations of the elements than the three epiphytic species. Tissue concentrations over the 3 years of sampling declined an average of 12%. Sufficient evidence exists to conclude that lichen tissue element concentrations in the vicinity of International Falls may be related to local air emissions, and that an exponential decline of element concentrations downwind of the sources does not apply to this situation.

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

NASA Astrophysics Data System (ADS)

Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

1984-07-01

Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

Velocity, bathymetry, and transverse mixing characteristics of the Ohio River upstream from Cincinnati, Ohio, October 2004-March 2006

USGS Publications Warehouse

Koltun, G.F.; Ostheimer, Chad J.; Griffin, Michael S.

2006-01-01

Velocity, bathymetry, and transverse (cross-channel) mixing characteristics were studied in a 34-mile study reach of the Ohio River extending from the lower pool of the Captain Anthony Meldahl Lock and Dam, near Willow Grove, Ky, to just downstream from the confluence of the Licking and Ohio Rivers, near Newport, Ky. Information gathered in this study ultimately will be used to parameterize hydrodynamic and water-quality models that are being developed for the study reach. Velocity data were measured at an average cross-section spacing of about 2,200 feet by means of boat-mounted acoustic Doppler current profilers (ADCPs). ADCP data were postprocessed to create text files describing the three-dimensional velocity characteristics in each transect. Bathymetry data were measured at an average transect spacing of about 800 feet by means of a boat-mounted single-beam echosounder. Depth information obtained from the echosounder were postprocessed with water-surface slope and elevation information collected during the surveys to compute stream-bed elevations. The bathymetry data were written to text files formatted as a series of space-delimited x-, y-, and z-coordinates. Two separate dye-tracer studies were done on different days in overlapping stream segments in an 18.3-mile section of the study reach to assess transverse mixing characteristics in the Ohio River. Rhodamine WT dye was injected into the river at a constant rate, and concentrations were measured in downstream cross sections, generally spaced 1 to 2 miles apart. The dye was injected near the Kentucky shoreline during the first study and near the Ohio shoreline during the second study. Dye concentrations were measured along transects in the river by means of calibrated fluorometers equipped with flow-through chambers, automatic temperature compensation, and internal data loggers. The use of flow-through chambers permitted water to be pumped continuously out of the river from selected depths and through the fluorometer for measurement as the boat traversed the river. Time-tagged concentration readings were joined with horizontal coordinate data simultaneously captured from a differentially corrected Global Positioning System (GPS) device to create a plain-text, comma-separated variable file containing spatially tagged dye-concentration data. Plots showing the transverse variation in relative dye concentration indicate that, within the stream segments sampled, complete transverse mixing of the dye did not occur. In addition, the highest concentrations of dye tended to be nearest the side of the river from which the dye was injected. Velocity, bathymetry, and dye-concentration data collected during this study are available for Internet download by means of hyperlinks in this report. Data contained in this report were collected between October 2004 and March 2006.

Effects of wildfires on ash Carbon, Nitrogen and C/N ratio in Mediterranean forests

NASA Astrophysics Data System (ADS)

Pereira, P.; Ubeda, X.; Martin, D. A.

2009-04-01

Carbon (C) and Nitrogen(N) are key nutrients in ecosystems health and the more affected by fire temperatures, because of their low temperatures of volatilization. After a wildfire, due higher temperatures reached, a great amount of C and N can be evacuated from the ecosystems and the percentage of C and N not vaporized is concentrated in ashes. Hence, the study of ash C and N is of major importance because will be linked with the capacity of ecosystem recuperation. The aim of this work is study the C, and C/N of three wildfires occurred in Mediterranean forests dominated by Quercus suber and Pinus pinea in Portugal. In the first wildfire, named "Quinta do Conde", we collected 30 samples, in the second, "Quinta da Areia", 32 samples and the third, "Casal do Sapo" 40 samples To estimate the consequences of wildfires in the parameters in study, we collected several samples of unburned litter near burned areas, composed by the same vegetation. The results showed that wildfires induced in % of Total Carbon (%TC) ashes content a non significantly reduction in Quinta do Conde plot (at a p<0,05) and significantly in Quinta da Areia plot (p<0.001) and Casal do Sapo plot (p<0.001). In % of Total Nitrogen (%TN) ashes content we observed in Quinta do Conde plot a significant increase (p<0.001), a non significant decrease in Quinta da Areia plot (at a p<0,05) and a significant reduce in Casal do Sapo plot (p<0.01). The The C/N ratio suffer a significant (p<0.001) reduction in Quinta do Conde and Quinta da Areia plots and at a p<0.01 in Casal do Sapo plot. In all parameters in study, wilfires induced a greater spatial variability, by the analysis of the Coefficient of Variation. Our tests effectuated in laboratory with samples collected near wildfires occurrence and exposed to the temperature gradient (150°, 200°, 250°, 300°, 350°, 400°, 450°, 500°, 550°C) fit with the results obtained. With temperature gradient, we identified a decrease of %TC ash content of Quercus suber samples and a rise until the 300°C in Pinus pinaster samples decreasing thereafter especially after the 400°C. In %TN we identified a rise in both species reducing abruptly at 450°C. C/N ratio decrease importantly after the 150°C. Theses results showed us that wildfires can have different effects C and N litter resources, depending on the severity and temperature reached. Crossing the results obtained in laboratory simulations with the samples collected in wildfires we will have an idea about the severity and temperature occurred in each wildfire. Overall, the lower severity were observed in Quinta do Conde plot and the higher in Casal do Sapo plot, being Quinta da Areia in a middle position. The C and N levels after a wildfire will determine the capacity of landscape recuperation and according the data obtained this will be higher in Quinta do Conde plot and lesser in Casal do Sapo plot. These hypothesis will be confirmed by field observation. Keywords: Carbon, Nitrogen, C/N ratio, wildfires, ashes, Quinta do Conde, Quinta da Areia, Casal do Sapo, Quercus suber, Pinus pinaster, Laboratory simulations, Severity, Landscape recuperation.

Generating Continuous Surface Probability Maps from Airborne Video Using Two Sampling Intensities Along the Video Transect

Treesearch

Dennis M. Jacobs; William H. Cooke

2000-01-01

Airborne videography can be an effective tool for assessing the effects of catastrophic events on forest conditions. However, there is some question about the appropriate sampling intensity to use, especially when trying to develop correlations with probabilistic data sets such as are assembled through the Forest Inventory and Analysis (FIA) surveys. We used airborne...

Occurrence of Cymbasoma longispinosum Bourne, 1890 in the Curuçá River estuary.

PubMed

Leite, Natália R; Pereira, Luci C C; Abrunhosa, Fernando; Pires, Marcus A B; Costa, Rauquírio M da

2010-09-01

The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 μm-mesh net tows from a small boat. Additional subsurface water samples were collected for the determination of environmental parameters. Males and females of Cymbasoma longispinosum were only observed during September and November/2003. The highest number of organisms was found in September/2003 at the Muriá River transect. The presence of C. longispinosum in samples obtained during September and November/2003 could probably be related to the reproductive period of this species in the studied estuary, which is directly related to the dry period in the region. The highest salinity values and the highest number of individuals observed in September/2003 corroborate with the previous assumption, since no C. longispinosum was found during the months comprising the rainy period (January to June).

Fire Effects at the Tundra-Boreal Ecotone in Interior Alaska

NASA Astrophysics Data System (ADS)

Howard, B. K.; Mack, M. C.; Johnstone, J. F.; Walker, X. J.; Roland, C.

2016-12-01

Climate warming in northern latitudes has led to an intensification of disturbance by wildfire. Little is known about the effects of fire on tundra vegetation. Changes in vegetation composition could have important implications for carbon cycling , and may feedback positively or negatively to future climate change (Randerson et al., 2006). Our study utilizes extensive pre-fire ecological data collected by the National Park Service (NPS) Inventory and Monitoring (I&M) program to assess the prefire conditions important in driving successional pathways within Denali National Park and Preserve. In 2013, the East Toklat fire burned 30,000 acres of tussock tundra and mixed white and black spruce forest at a high severity, which encompassed 50 NPS plots that were originally monitored in 2003. Our sampling occurred the summer of 2016 following the same NPS protocols to assess post-fire vegetation composition. In addition, we conducted a seeding experiment using locally collected white and black spruce seed to assess natural and potential tree regeneration in unburned and post fire environments. Seed traps were established along our transects to assess seed rain. A multivariate approach will be used to assess post-fire community dynamics and future field seasons will address tree germination and survival rates. These data will then be coupled with pre and post-fire ecological data to parse out important factors driving secondary succession.

Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

PubMed

Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

2016-03-01

We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities.

Examining patterns of bat activity in Bandelier National Monument, New Mexico, using walking point transects

USGS Publications Warehouse

Ellison, L.E.; Everette, A.L.; Bogan, M.A.

2005-01-01

We conducted a preliminary study using small field crews, a single Anabat II detector coupled with a laptop computer, and point transects to examine patterns of bat activity at a scale of interest to local resource managers. The study was conducted during summers of 1996–1998 in Bandelier National Monument in the Jemez Mountains of northern New Mexico, a landscape with distinct vegetation zones and high species richness of bats. We developed simple models that described general patterns of acoustic activity within 4 vegetation zones based primarily on nightly variation and a qualitative index of habitat complexity. Bat acoustic activity (number of bat passes&sol point) did not vary dramatically among a limited sample of transects within a vegetation zone during 1996. In 1997 and 1998, single transects within each vegetation zone were established, and bat activity did not vary annually within these zones. Acoustic activity differed among the 4 vegetation zones of interest, with the greatest activity occurring in riparian canyon bottomland, intermediate activity in coniferous forest and a 1977 burned zone, and lowest activity in piñon-juniper woodlands. We identified 68.5% of 2,529 bat passes recorded during point-transect surveys to species using an echolocation call reference library we established for the area and qualitative characteristics of bat calls. Bat species richness and composition differed among vegetation zones. Results of these efforts were consistent with general knowledge of where different bat species typically forage and with the natural history of bats of New Mexico, suggesting such a method might have value for drawing inferences about bat activity in different vegetation zones.

Fish populations associated with habitat-modified piers and natural woody debris in Piedmont Carolina reservoirs

USGS Publications Warehouse

Barwick, R.D.; Kwak, T.J.; Noble, R.L.; Barwick, D.H.

2004-01-01

A primary concern associated with reservoir shoreline residential development is reduction of littoral habitat complexity and diversity. One potential approach to compensate for this is the deployment of artificial-habitat modules under existing piers, but the benefit of this practice has not been demonstrated. To evaluate the effect of pier habitat modifications on fish populations in two Piedmont Carolina reservoirs, we studied 77 piers located on forty-seven, 100-m transects that were modified using plastic "fish hab" modules augmented with brush (brushed habs), hab modules alone (habs), or left unaltered for reference purposes. We sampled fish from all piers and transects during April, July, and October 2001 using a boat-mounted electrofisher. With few exceptions, catch rates were higher at brushed-hab piers and piers with habs than at reference piers during all seasons. Similarly, during spring and summer, fish abundance was generally higher on transects containing natural woody debris, brushed habs, and habs than on reference-developed transects; however, during fall, there were exceptions. Therefore, fish abundance associated with shorelines in these reservoirs appears to be related to the structural complexity of available habitat rather than structure composition. One year after installation, 92% of pier owners responding to a mail survey expressed satisfaction with pier modifications. Supplementing piers with habitat structures is recommended to enhance littoral habitat complexity for fishes in residentially developed reservoirs.

Spatial patterns of soil nitrification and nitrate export from forested headwaters in the northeastern United States

USGS Publications Warehouse

Ross, D.S.; Shanley, J.B.; Campbell, J.L.; Lawrence, G.B.; Bailey, S.W.; Likens, G.E.; Wemple, B.C.; Fredriksen, G.; Jamison, A.E.

2012-01-01

Nitrogen export from small forested watersheds is known to be affected by N deposition but with high regional variability. We studied 10 headwater catchments in the northeastern United States across a gradient of N deposition (5.4 - 9.4 kg ha -1 yr -1) to determine if soil nitrification rates could explain differences in stream water NO 3 - export. Average annual export of two years (October 2002 through September 2004) varied from 0.1 kg NO 3 --N ha -1 yr -1 at Cone Pond watershed in New Hampshire to 5.1 kg ha -1 yr -1 at Buck Creek South in the western Adirondack Mountains of New York. Potential net nitrification rates and relative nitrification (fraction of inorganic N as NO 3 -) were measured in Oa or A soil horizons at 21-130 sampling points throughout each watershed. Stream NO 3 - export was positively related to nitrification rates (r 2 = 0.34, p = 0.04) and the relative nitrification (r 2 = 0.37, p = 0.04). These relationships were much improved by restricting consideration to the 6 watersheds with a higher number of rate measurements (59-130) taken in transects parallel to the streams (r 2 of 0.84 and 0.70 for the nitrification rate and relative nitrification, respectively). Potential nitrification rates were also a better predictor of NO 3 - export when data were limited to either the 6 sampling points closest to the watershed outlet (r 2 = 0.75) or sampling points <250 m from the watershed outlet (r 2 = 0.68). The basal area of conifer species at the sampling plots was negatively related to NO 3 - export. These spatial relationships found here suggest a strong influence of near-stream and near-watershed-outlet soils on measured stream NO 3 - export. Copyright 2012 by the American Geophysical Union.

Red imported fire ant impacts on upland arthropods in Southern Mississippi

USGS Publications Warehouse

Epperson, D.M.; Allen, Craig R.

2010-01-01

Red imported fire ants (Solenopsis invicta) have negative impacts on a broad array of invertebrate species. We investigated the impacts of fire ants on the upland arthropod community on 20???40 ha study sites in southern Mississippi. Study sites were sampled from 19972000 before, during, and after fire ant bait treatments to reduce fire ant populations. Fire ant abundance was assessed with bait transects on all sites, and fire ant population indices were estimated on a subset of study sites. Species richness and diversity of other ant species was also assessed from bait transects. Insect biomass and diversity was determined from light trap samples. Following treatments, fire ant abundance and population indices were significantly reduced, and ant species diversity and richness were greater on treated sites. Arthropod biomass, species diversity and species richness estimated from light trap samples were negatively correlated with fire ant abundance, but there were no observable treatment effects. Solenopsis invicta has the potential to negatively impact native arthropod communities resulting in a potential loss of both species and function.

Surface-sediment grain-size distribution and sediment transport in the subaqueous Mekong Delta, Vietnam

NASA Astrophysics Data System (ADS)

Nguyen, T. T.; Stattegger, K.; Nittrouer, C.; Phung, P. V.; Liu, P.; DeMaster, D. J.; Bui, D. V.; Le, A. D.; Nguyen, T. N.

2016-02-01

Collected surface-sediment samples in coastal water around Mekong Delta (from distributary channels to Ca Mau Peninsula) were analyzed to determine surface-sediment grain-size distribution and sediment-transport trend in the subaqueous Mekong Delta. The grain-size data set of 238 samples was obtained by using the laser instrument Mastersizer 2000 and LS Particle Size Analyzer. Fourteen samples were selected for geochemical analysis (total-organic and carbonate content). These geochemical results were used to assist in interpreting variations of granulometricparamenters along the cross-shore transects. Nine transects were examined from CungHau river mouth to Ca Mau Peninsula and six thematic maps on the whole study area were made. The research results indicate that: (1) generally, the sediment becomes finer from the delta front downwards to prodelta and becomes coarser again and poorer sorted on the adjacent inner shelf due to different sources of sediment; (2) sediment-granulometry parameters vary among sedimentary sub-environments of the underwater part of Mekong Delta, the distance from sediment source and hydrodynamic regime controlling each region; (3) the net sediment transport is southwest toward the Ca Mau Peninsula.

Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data

USGS Publications Warehouse

Junttila, Virpi; Kauranne, Tuomo; Finley, Andrew O.; Bradford, John B.

2015-01-01

Modern operational forest inventory often uses remotely sensed data that cover the whole inventory area to produce spatially explicit estimates of forest properties through statistical models. The data obtained by airborne light detection and ranging (LiDAR) correlate well with many forest inventory variables, such as the tree height, the timber volume, and the biomass. To construct an accurate model over thousands of hectares, LiDAR data must be supplemented with several hundred field sample measurements of forest inventory variables. This can be costly and time consuming. Different LiDAR-data-based and spatial-data-based sampling designs can reduce the number of field sample plots needed. However, problems arising from the features of the LiDAR data, such as a large number of predictors compared with the sample size (overfitting) or a strong correlation among predictors (multicollinearity), may decrease the accuracy and precision of the estimates and predictions. To overcome these problems, a Bayesian linear model with the singular value decomposition of predictors, combined with regularization, is proposed. The model performance in predicting different forest inventory variables is verified in ten inventory areas from two continents, where the number of field sample plots is reduced using different sampling designs. The results show that, with an appropriate field plot selection strategy and the proposed linear model, the total relative error of the predicted forest inventory variables is only 5%–15% larger using 50 field sample plots than the error of a linear model estimated with several hundred field sample plots when we sum up the error due to both the model noise variance and the model’s lack of fit.

Primary non-transecting bulbar urethroplasty long-term success rates are similar to transecting urethroplasty.

PubMed

Anderson, Kirk M; Blakely, Stephen A; O'Donnell, Colin I; Nikolavsky, Dmitriy; Flynn, Brian J

2017-01-01

To review the long-term outcomes of transecting versus non-transecting urethroplasty to repair bulbar urethral strictures. A retrospective review was conducted of 342 patients who underwent anterior urethroplasty performed by a single surgeon from 2003 to 2014. Patients were excluded from further analysis if there had been prior urethroplasty, stricture location outside the bulbous urethra, or age <18 years. In the transecting group, surgical techniques used included excision and primary anastomosis and augmented anastomotic urethroplasty. In the non-transecting group, surgical techniques used included non-transecting anastomotic urethroplasty and dorsal and/or ventral buccal grafting. The primary endpoint was stricture resolution in transecting vs. non-transecting bulbar urethroplasty. Success was defined as freedom from secondary procedures including dilation, urethrotomy, or repeat urethroplasty. One hundred and fifty-two patients met inclusion criteria. At a mean follow-up of 65 months (range: 10-138 months), stricture-free recurrence in the transecting and non-transecting groups was similar, 83% (n = 85/102) and 82% (n = 41/50), respectively (p = 0.84). Surgical technique (p = 0.91), stricture length (p = 0.8), and etiology (p = 0.6) did not affect stricture recurrence rate on multivariate analysis. There was no difference detected in time to stricture recurrence (p = 0.21). In this retrospective series, transecting and non-transecting primary bulbar urethroplasty resulted in similar long-term stricture resolution rate. Prospective studies are needed to determine what differences may present in outcomes related to sexual function and long-term success.

Tracing Sources of Organic Matter and Nitrate in the San Francisco Bay-Delta-River Ecosystem Using Isotopic Techniques: Comparison of Insights Gained from Fixed-site, Synoptic, and Diel Sampling Strategies

NASA Astrophysics Data System (ADS)

Kendall, C.; Silva, S. R.; Doctor, D. H.; Wankel, S. D.; Chang, C. C.; Bergamaschi, B. A.; Kratzer, C. R.; Dahlgren, R. A.; Fleenor, W. E.

2005-12-01

Understanding the sources and sinks for organics and nitrate is critical for devising effective strategies to reduce their loads in ecosystems and mitigate local problems of low dissolved oxygen levels and/or production of disinfection byproducts during water treatment. Since isotopic techniques are effective methods for quantifying the sources and sinks of organics and nutrients, we have analyzed particulate organic matter (POM), nitrate, dissolved inorganic and organic carbon (DIC, DOC), and water isotope samples from selected sites since 2000. Our studies indicate that isotope data are a useful adjunct to traditional methods for assessing and monitoring sources of organics and nutrients. The original sampling in 2000-2001 used the classical fixed-site and fixed-time interval sampling approach, where sites on the San Joaquin River and its major tributaries were sampled bimonthly from July to October for chemistry and isotopes (Kratzer et al., 2004: see URL below). Subsequently, samples were collected during 4 transects along the San Joaquin River (10/02, 3/03, 9/03, and 7/04); the first and last of these transects extended through the Delta to the Bay. Several sites were sampled during diel studies in 8/04 and 7/05. Although fixed-site sampling is the norm in watershed studies, we have found that isotope and chemical data collected during longitudinal transects of the river and diel sampling of several sites along short river reaches have been more useful in convincing colleagues that isotope measurements are extremely useful adjuncts to traditional methods for assessing and monitoring sources of organics and nutrients during ecosystem restoration programs. Furthermore, we have concluded that while the obvious value of isotopes for water resources management is to tell us things about water resources that we didn't know before, what convinces the skeptic is when the isotopes tell us things about water resources that contradict what we thought we knew before. This work will highlight these and other insights developed using varied sampling strategies, and suggest guidelines for how to approach future studies in biologically active and human impacted rivers like the San Joaquin River system.

Physical and Chemical Data from Eolian Sediment Collected Along a Transect from the Mojave Desert to the Colorado Plateau

USGS Publications Warehouse

Goldstein, Harland L.; Reynolds, Richard L.; Reheis, Marith C.; Yount, James C.; Lamothe, Paul J.

2007-01-01

This report presents data and describes the methodology for magnetic, geochemical, and textural measurements of sediment and bedrock samples collected along a transect across the Southwestern United States (fig. 1). The results presented here support a study that examines compositional variations of mineral dust deposited during the past few centuries in isolated natural traps spanning a region from the Mojave Desert of southern California to the central Colorado Plateau (Goldstein and others, in press; fig. 1). In particular, the study addresses the spatial and temporal variations in dust composition in the context of landscape geochemistry over a large area of the southwestern United States.

Sampling plantations to determine white-pine weevil injury

Treesearch

Robert L. Talerico; Robert W., Jr. Wilson

1973-01-01

Use of 1/10-acre square plots to obtain estimates of the proportion of never-weeviled trees necessary for evaluating and scheduling white-pine weevil control is described. The optimum number of trees to observe per plot is estimated from data obtained from sample plantations in the Northeast and a table is given. Of sample size required to achieve a standard error of...

VAM populations in relation to grass invasion associated with forest decline.

PubMed

Vosatka, M; Cudlin, P; Mejstrik, V

1991-01-01

Spruce stands in Northern Bohemia forests, damaged to various degrees by industrial pollution, have shown establishment of grass cover following tree defoliation. Populations of vesicular-arbuscular mycorrhizal (VAM) fungi were studied under this grass cover in four permanent plots with spruce under different levels of pollution stress. Soil and root samples were collected in April and June within each plot as follows: (1) sites without grass, (2) sites with initial stages of grass invasion, and (3) sites with fully developed grass cover. In all plots, the highest number of propagules were recovered from samples taken from sites having full grass cover. Mycorrhizal infection of grass was highest in the plot with the severest pollution damage and lowest in the least damaged plot. The development of grass cover and VAM infection of grass increased with tree defoliation caused by air pollution.

Plot shape effects on plant species diversity measurements

USGS Publications Warehouse

Keeley, Jon E.; Fotheringham, C.J.

2005-01-01

Abstract. Question: Do rectangular sample plots record more plant species than square plots as suggested by both empirical and theoretical studies?Location: Grasslands, shrublands and forests in the Mediterranean-climate region of California, USA.Methods: We compared three 0.1-ha sampling designs that differed in the shape and dispersion of 1-m2 and 100-m2 nested subplots. We duplicated an earlier study that compared the Whittaker sample design, which had square clustered subplots, with the modified Whittaker design, which had dispersed rectangular subplots. To sort out effects of dispersion from shape we used a third design that overlaid square subplots on the modified Whittaker design. Also, using data from published studies we extracted species richness values for 400-m2 subplots that were either square or 1:4 rectangles partially overlaid on each other from desert scrub in high and low rainfall years, chaparral, sage scrub, oak savanna and coniferous forests with and without fire.Results: We found that earlier empirical reports of more than 30% greater richness with rectangles were due to the confusion of shape effects with spatial effects, coupled with the use of cumulative number of species as the metric for comparison. Average species richness was not significantly different between square and 1:4 rectangular sample plots at either 1- or 100-m2. Pairwise comparisons showed no significant difference between square and rectangular samples in all but one vegetation type, and that one exhibited significantly greater richness with squares. Our three intensive study sites appear to exhibit some level of self-similarity at the scale of 400 m2, but, contrary to theoretical expectations, we could not detect plot shape effects on species richness at this scale.Conclusions: At the 0.1-ha scale or lower there is no evidence that plot shape has predictable effects on number of species recorded from sample plots. We hypothesize that for the mediterranean-climate vegetation types studied here, the primary reason that 1:4 rectangles do not sample greater species richness than squares is because species turnover varies along complex environmental gradients that are both parallel and perpendicular to the long axis of rectangular plots. Reports in the literature of much greater species richness recorded for highly elongated rectangular strips than for squares of the same area are not likely to be fair comparisons because of the dramatically different periphery/area ratio, which includes a much greater proportion of species that are using both above and below-ground niche space outside the sample area.

A Unimodal Model for Double Observer Distance Sampling Surveys.

PubMed

Becker, Earl F; Christ, Aaron M

2015-01-01

Distance sampling is a widely used method to estimate animal population size. Most distance sampling models utilize a monotonically decreasing detection function such as a half-normal. Recent advances in distance sampling modeling allow for the incorporation of covariates into the distance model, and the elimination of the assumption of perfect detection at some fixed distance (usually the transect line) with the use of double-observer models. The assumption of full observer independence in the double-observer model is problematic, but can be addressed by using the point independence assumption which assumes there is one distance, the apex of the detection function, where the 2 observers are assumed independent. Aerially collected distance sampling data can have a unimodal shape and have been successfully modeled with a gamma detection function. Covariates in gamma detection models cause the apex of detection to shift depending upon covariate levels, making this model incompatible with the point independence assumption when using double-observer data. This paper reports a unimodal detection model based on a two-piece normal distribution that allows covariates, has only one apex, and is consistent with the point independence assumption when double-observer data are utilized. An aerial line-transect survey of black bears in Alaska illustrate how this method can be applied.

Analysis of Sample Size, Counting Time, and Plot Size from an Avian Point Count Survey on Hoosier National Forest, Indiana

Treesearch

Frank R. Thompson; Monica J. Schwalbach

1995-01-01

We report results of a point count survey of breeding birds on Hoosier National Forest in Indiana. We determined sample size requirements to detect differences in means and the effects of count duration and plot size on individual detection rates. Sample size requirements ranged from 100 to >1000 points with Type I and II error rates of <0.1 and 0.2. Sample...

Procedures to handle inventory cluster plots that straddle two or more conditions

Treesearch

Jerold T. Hahn; Colin D. MacLean; Stanford L. Arner; William A. Bechtold

1995-01-01

We review the relative merits and field procedures for four basic plot designs to handle forest inventory plots that straddle two or more conditions, given that subplots will not be moved. A cluster design is recommended that combines fixed-area subplots and variable-radius plot (VRP) sampling. Each subplot in a cluster consists of a large fixed-area subplot for...

A Simulation Approach to Assessing Sampling Strategies for Insect Pests: An Example with the Balsam Gall Midge

PubMed Central

Carleton, R. Drew; Heard, Stephen B.; Silk, Peter J.

2013-01-01

Estimation of pest density is a basic requirement for integrated pest management in agriculture and forestry, and efficiency in density estimation is a common goal. Sequential sampling techniques promise efficient sampling, but their application can involve cumbersome mathematics and/or intensive warm-up sampling when pests have complex within- or between-site distributions. We provide tools for assessing the efficiency of sequential sampling and of alternative, simpler sampling plans, using computer simulation with “pre-sampling” data. We illustrate our approach using data for balsam gall midge (Paradiplosis tumifex) attack in Christmas tree farms. Paradiplosis tumifex proved recalcitrant to sequential sampling techniques. Midge distributions could not be fit by a common negative binomial distribution across sites. Local parameterization, using warm-up samples to estimate the clumping parameter k for each site, performed poorly: k estimates were unreliable even for samples of n∼100 trees. These methods were further confounded by significant within-site spatial autocorrelation. Much simpler sampling schemes, involving random or belt-transect sampling to preset sample sizes, were effective and efficient for P. tumifex. Sampling via belt transects (through the longest dimension of a stand) was the most efficient, with sample means converging on true mean density for sample sizes of n∼25–40 trees. Pre-sampling and simulation techniques provide a simple method for assessing sampling strategies for estimating insect infestation. We suspect that many pests will resemble P. tumifex in challenging the assumptions of sequential sampling methods. Our software will allow practitioners to optimize sampling strategies before they are brought to real-world applications, while potentially avoiding the need for the cumbersome calculations required for sequential sampling methods. PMID:24376556

Effects of processed oil shale on the element content of Atriplex cancescens

USGS Publications Warehouse

Anderson, B.M.

1982-01-01

Samples of four-wing saltbush were collected from the Colorado State University Intensive Oil Shale Revegetation Study Site test plots in the Piceance basin, Colorado. The test plots were constructed to evaluate the effects of processed oil shale geochemistry on plant growth using various thicknesses of soil cover over the processed shale and/or over a gravel barrier between the shale and soil. Generally, the thicker the soil cover, the less the influence of the shale geochemistry on the element concentrations in the plants. Concentrations of 20 elements were larger in the ash of four-wing saltbush growing on the plot with the gravel barrier (between the soil and processed shale) when compared to the sample from the control plot. A greater water content in the soil in this plot has been reported, and the interaction between the increased, percolating water and shale may have increased the availability of these elements for plant uptake. Concentrations of boron, copper, fluorine, lithium, molybdenum, selenium, silicon, and zinc were larger in the samples grown over processed shale, compared to those from the control plot, and concentrations for barium, calcium, lanthanum, niobium, phosphorus, and strontium were smaller. Concentrations for arsenic, boron, fluorine, molybdenum, and selenium-- considered to be potential toxic contaminants--were similar to results reported in the literature for vegetation from the test plots. The copper-to-molybdenum ratios in three of the four samples of four-wing saltbush growing over the processed shale were below the ratio of 2:1, which is judged detrimental to ruminants, particularly cattle. Boron concentrations averaged 140 ppm, well above the phytotoxicity level for most plant species. Arsenic, fluorine, and selenium concentrations were below toxic levels, and thus should not present any problem for revegetation or forage use at this time.

Saugus River and Tributaries, Lynn Malden, Revere and Saugus, Massachusetts. Flood Damage Reduction. Volume 8. Appendix K. Environmental

DTIC Science & Technology

1989-06-01

K10 Summary of Soil Analyses for the Salt Marsh Transects K32 KI1 Plant Community Composition Data Along Compartment K33 B Transect K12 Plant...Community Composition Data Along Compartment K33 I Transect K13 Plant Community Composition Data Along Compartment K33 K1 Transect K14 Plant Community... Composition Data Along Compartment K34 K3 Transect K15 Plant Community Composition Data Along Compartment K34 L2 Transect K16 Plant Community Composition

Cooperative Alaska Forest Inventory

Treesearch

Thomas Malone; Jingjing Liang; Edmond C. Packee

2009-01-01

The Cooperative Alaska Forest Inventory (CAFI) is a comprehensive database of boreal forest conditions and dynamics in Alaska. The CAFI consists of field-gathered information from numerous permanent sample plots distributed across interior and south-central Alaska including the Kenai Peninsula. The CAFI currently has 570 permanent sample plots on 190 sites...

EFFECTS OF REPEATED DROUGHTS ON SOIL MICROARTHROPOD COMMUNITIES IN THE NORTHERN CHIHUHUAN DESERT

EPA Science Inventory

Soil microarthropods were sampled in plots centered on creosotebushes(Larrea tridentata) and in plots centered on mesquite(Prosopis glandulosa) coppice dunes. Nine plots in each area were covered by rain-out shelters with greenhouse plastic roofs which excluded natural rainfall a...

Ground sample data for the Conterminous U.S. Land Cover Characteristics Database

Treesearch

Robert Burgan; Colin Hardy; Donald Ohlen; Gene Fosnight; Robert Treder

1999-01-01

Ground sample data were collected for a land cover database and raster map that portray 159 vegetation classes at 1 km2 resolution for the conterminous United States. Locations for 3,500 1 km2 ground sample plots were selected randomly across the United States. The number of plots representing each vegetation class was weighted by the proportionate coverage of each...

A hierarchical model combining distance sampling and time removal to estimate detection probability during avian point counts

USGS Publications Warehouse

Amundson, Courtney L.; Royle, J. Andrew; Handel, Colleen M.

2014-01-01

Imperfect detection during animal surveys biases estimates of abundance and can lead to improper conclusions regarding distribution and population trends. Farnsworth et al. (2005) developed a combined distance-sampling and time-removal model for point-transect surveys that addresses both availability (the probability that an animal is available for detection; e.g., that a bird sings) and perceptibility (the probability that an observer detects an animal, given that it is available for detection). We developed a hierarchical extension of the combined model that provides an integrated analysis framework for a collection of survey points at which both distance from the observer and time of initial detection are recorded. Implemented in a Bayesian framework, this extension facilitates evaluating covariates on abundance and detection probability, incorporating excess zero counts (i.e. zero-inflation), accounting for spatial autocorrelation, and estimating population density. Species-specific characteristics, such as behavioral displays and territorial dispersion, may lead to different patterns of availability and perceptibility, which may, in turn, influence the performance of such hierarchical models. Therefore, we first test our proposed model using simulated data under different scenarios of availability and perceptibility. We then illustrate its performance with empirical point-transect data for a songbird that consistently produces loud, frequent, primarily auditory signals, the Golden-crowned Sparrow (Zonotrichia atricapilla); and for 2 ptarmigan species (Lagopus spp.) that produce more intermittent, subtle, and primarily visual cues. Data were collected by multiple observers along point transects across a broad landscape in southwest Alaska, so we evaluated point-level covariates on perceptibility (observer and habitat), availability (date within season and time of day), and abundance (habitat, elevation, and slope), and included a nested point-within-transect and park-level effect. Our results suggest that this model can provide insight into the detection process during avian surveys and reduce bias in estimates of relative abundance but is best applied to surveys of species with greater availability (e.g., breeding songbirds).

Branchfall as a Demographic Filter for Epiphyte Communities: Lessons from Forest Floor-Based Sampling

PubMed Central

Sarmento Cabral, Juliano; Petter, Gunnar; Mendieta-Leiva, Glenda; Wagner, Katrin; Zotz, Gerhard; Kreft, Holger

2015-01-01

Local variation in the abundance and richness of vascular epiphytes is often attributed to environmental characteristics such as substrate and microclimate. Less is known, however, about the impacts of tree and branch turnover on epiphyte communities. To address this issue, we surveyed branches and epiphytes found on the forest floor in 96 transects in two forests (Atlantic rainforest in Brazil and Caribbean rainforest in Panama). In the Brazilian forest, we additionally distinguished between edge and core study sites. We quantified branch abundance, epiphyte abundance, richness and proportion of adults to investigate the trends of these variables over branch diameter. Branches <2 cm in diameter comprised >90% of all branches on the forest floor. Abundance and richness of fallen epiphytes per transect were highest in the Brazilian core transects and lowest in the Panamanian transects. The majority of epiphytes on the floor (c. 65%) were found attached to branches. At all three study sites, branch abundance and branch diameter were negatively correlated, whereas epiphyte abundance and richness per branch, as well as the proportion of adults were positively correlated with branch diameter. The relationship between branch diameter and absolute epiphyte abundance or richness differed between study sites, which might be explained by differences in forest structure and dynamics. In the Panamanian forest, epiphytes had been previously inventoried, allowing an evaluation of our surveying method by comparing canopy and forest floor samplings. Individuals found on the forest floor corresponded to 13% of all individuals on branches <10 cm in diameter (including crowns), with abundance, richness and composition trends on forest floor reflecting canopy trends. We argue that forest floor surveys provide useful floristic and, most notably, demographic information particularly on epiphytes occurring on the thinnest branches, which are least accessible. Here, branchfall acts as an important demographic filter structuring epiphyte communities. PMID:26083417

Carbon and Nitrogen Response to Forced Inundation of Hyporheic Sediment along an Elevational Transect of the Columbia River

NASA Astrophysics Data System (ADS)

Goldman, A. E.; Graham, E.; Crump, A.; Kennedy, D.; Romero, E. B.; Anderson, C.; Dana, K. L.; Fredrickson, J.; Stegen, J.

2016-12-01

Diel and seasonal fluctuations of river water discharge in the dam-controlled Hanford Reach of the Columbia River (Washington State, USA) result in irregular wetting and drying of hyporheic sediments within ten meters of the shoreline. As such, nearshore inundation histories vary from seconds to years since last river water exposure and have generated a gradient in groundcover ranging from barren gravel to sparse grasses to trees. In order to understand how history of inundation influences the response of carbon and nitrogen cycling to rewetting, we conducted 0.5-hour and 25-hour forced-inundation laboratory incubations on samples collected every two meters along three 6-meter elevational transects of shoreline along the Hanford Reach. At the time of sample collection, sediment along our elevational transect ranged from currently inundated to one year since last inundation. Incubation sediments were characterized based on spatial and temporal changes in nitrogen and carbon characteristics. We measured headspace CO2, non-particulate organic carbon (NPOC), total organic matter, organic acids, C/N, NO3-, NO2-, NH4+, pH, and moisture content. We found high rates of aerobic respiration at the lowest elevations, attributed to an initial pulse of CO2 not seen at higher elevations, and accumulation of labile organic carbon (i.e., glucose, NPOC) at the highest elevations. We are currently investigating microbial communities with 16S and ITS sequencing in order to explore potential community shifts along the transect and linkages between fungal communities and nitrogen cycling. Our results suggest that inundation history may lead to spatial isolation of microbial communities with subsequent differences in ability to respond to wet-dry cycles. Examining how variations in hydrology impact carbon and nitrogen cycling allows for a more robust understanding of how climate change may alter microbially-mediated interactions and transformations within the hyporheic zone.

Optimization of Surveys with Internet Operated Deep-sea Crawlers, as an Integrated Tool for Ocean Cabled Observatories: Monitoring the Benthic Community of a Methane Hydrates Site in Barkley Canyon (BC, Canada)

NASA Astrophysics Data System (ADS)

Chatzievangelou, D.; Suarez, A.; Aguzzi, J.; Bigham, K.; Thomsen, L.

2017-12-01

Deep-sea research is entering an era of coordinated, multidisciplinary monitoring of benthic ecosystems, from local and regional to global scale. Technological advances, such as the development of ocean cabled observatories and mobile vehicles operating within them, raise the issue of "smart" study designs. The objective is optimizing the balance among reduced effort (i.e. sampling, data transfer and storage, a posteriori treatment), accurate representation of the monitored ecosystems and a minimal ecological footprint. For this study, 18 linear imaging transects ( 25 m each, 1 Hz frequency) were performed by the Internet Operated Deep-sea Crawler "Wally" at the Barkley Canyon hydrates site (870 m depth) within the Ocean Networks Canada NEPTUNE observatory, generating a total of 19920 images. In order to evaluate sampling effort, species accumulation curves were calculated against the number of transects, and the permanence time of mobile individuals in the crawler's field of view was used to assess the number of individuals captured for different potential imaging frequencies. The effect of the crawler caterpillars on benthic organisms was evaluated by comparing the images of disturbed (i.e previous tracks) vs. undisturbed seabed. The analyses showed that maximum species richness (i.e. 18 species) was achieved after 10 transects, while 0.33 Hz and 0.5 Hz imaging frequencies captured more than 95% of the individuals counted with the original 1 Hz method. Preliminary results indicate no differences in the numbers of benthic animals between the disturbed and the undisturbed seabed parts. These findings allow the design of future experiments under similar conditions with minimized costs and effort without compromising data quality. Finally, the low invasiveness of the crawler as a monitoring platform, as long as certain protocols are followed, is highlighted. Ongoing analyses of the same transects assess the varying macro- and megafauna, in relation to the distance from a nearby, small ( 2-3 m high) hydrate mound.

Agricultural matrices affect ground ant assemblage composition inside forest fragments

PubMed Central

Dos Santos, Iracenir Andrade; Ramos, Flavio Nunes; Majer, Jonathan David; Vilela, Evaldo Ferreira

2018-01-01

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was ‘generalist’ both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an ‘ocean of crops’. PMID:29791493

Agricultural matrices affect ground ant assemblage composition inside forest fragments.

PubMed

Assis, Diego Santana; Dos Santos, Iracenir Andrade; Ramos, Flavio Nunes; Barrios-Rojas, Katty Elena; Majer, Jonathan David; Vilela, Evaldo Ferreira

2018-01-01

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was 'generalist' both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an 'ocean of crops'.

Neutral carbohydrate geochemistry of particulate material in the central equatorial Pacific

NASA Astrophysics Data System (ADS)

Hernes, Peter J.; Hedges, John I.; Peterson, Michael L.; Wakeham, Stuart G.; Lee, Cindy

Neutral carbohydrate compositions were determined for particulate samples from plankton net tows, shallow floating sediment traps, mid-depth and deep moored sediment traps, and sediment cores collected along a north-south transect in the central equatorial Pacific Ocean during the U.S. JGOFS EqPac program. Total neutral carbohydrate depth profiles and patterns along the transect follow essentially the same trends as bulk and organic carbon (OC) fluxes—attenuating with depth, high near the equator and decreasing poleward. OC-normalized total aldose (TCH 2,O) yields along the transect and with depth do not show any consitent patterns. Relative to a planktonic source, neutral carbohydrate compositions in sediment trap and sediment core samples reflect preferential loss of ribose and storage carbohydrates rich in glucose, and preferential preservation of structural carbohydrates rich in rhamnose, xylose, fucose, and mannose. There is also evidence for an intermediately labile component rich in galactose. It appears that compositional signatures of neutral carbohydrates in sediments are more dependent upon their planktonic source than on any particular diagenetic pathway. Relative to other types of organic matter, neutral carbohydrates are better preserved in calcareous oozes from 12°S to 5°N than in red clays at 9°N based on OC-normalized TCH 2O yields, due to either differing sources or sorption characteristics. Weight per cent glucose generally decreases with increased degradation of organic material in the central equatorial Pacific region. Based on weight per cent glucose, comparisons of samples between Survey I (El Niõn) and Survey II (non-El Niño) indicate that during Survey I, organic material in the epipelagic zone in the northern hemisphere may have undergone more degradation than organic material in the southern hemisphere.

Spatial and Temporal Genetic Analyses Show High Gene Flow Among European Corn Borer (Lepidoptera: Crambidae) Populations Across the Central U.S. Corn Belt

USDA-ARS?s Scientific Manuscript database

European corn borer, Ostrinia nubilalis, were sampled at 13 sites along two perpendicular 720 km transects intersecting in central Iowa, and two generations later at 4 of the same sites separated by 150-km in the cardinal directions. More than 50 moths from each sample location and time were genoty...

Impact and Recovery Pattern of a Spring Fire on a Pacific Coast Marsh - Observations and Implications for Endangered Species

NASA Astrophysics Data System (ADS)

Brown, L. N.; Willis, K. S.; Ambrose, R. F.; MacDonald, G. M.

2015-12-01

The flammability of California coastal marsh vegetation is highest in winter and spring when dominant high marsh plants such as Sarcocornia pacifica are dormant. With climate change the number of cool-season fires are increasing in the state, and marsh systems are becoming more vulnerable to fire disturbance. Very little information exists in peer-reviewed or grey literature on the presence of fire in Pacific Coast tidal marshes. In 1993, the Green Meadows fire in Ventura County, California burned a small portion of tidally influenced Sarcocornia­-dominated marsh at Point Mugu. After the May 2013 Springs Fire burned a similar portion of the salt marsh vegetation, we conducted a two-year vegetation recovery survey using transects of surface vegetation plots and MODIS derived NDVI remote sensing monitoring. Recovery during the first year was limited. Sixteen months into the recovery period, percent plant coverage reached an average of approximately 60% for all plots in the burned area, as opposed to an average of 100% in control plots, and remained at that level for the duration of the study. NDVI did not approach near pre-fire conditions until 19 months after the fire. While recovery may have been influenced by California's current extreme drought conditions, the recurrence of fire and rate of recovery raise many important questions as to the role of fire in Pacific coast tidal marshes. For example, the lack of Salicornia cover over more than an entire breeding season would be detrimental to protected species such as Rallus obsoletus. Fire adds new vulnerabilities on critical tidal marsh habitat already taxed by the threat of sea-level rise, coastal squeeze and invasive species.

Detailed p- and s-wave velocity models along the LARSE II transect, Southern California

USGS Publications Warehouse

Murphy, J.M.; Fuis, G.S.; Ryberg, T.; Lutter, W.J.; Catchings, R.D.; Goldman, M.R.

2010-01-01

Structural details of the crust determined from P-wave velocity models can be improved with S-wave velocity models, and S-wave velocities are needed for model-based predictions of strong ground motion in southern California. We picked P- and S-wave travel times for refracted phases from explosive-source shots of the Los Angeles Region Seismic Experiment, Phase II (LARSE II); we developed refraction velocity models from these picks using two different inversion algorithms. For each inversion technique, we calculated ratios of P- to S-wave velocities (VP/VS) where there is coincident P- and S-wave ray coverage.We compare the two VP inverse velocity models to each other and to results from forward modeling, and we compare the VS inverse models. The VS and VP/VS models differ in structural details from the VP models. In particular, dipping, tabular zones of low VS, or high VP/VS, appear to define two fault zones in the central Transverse Ranges that could be parts of a positive flower structure to the San Andreas fault. These two zones are marginally resolved, but their presence in two independent models lends them some credibility. A plot of VS versus VP differs from recently published plots that are based on direct laboratory or down-hole sonic measurements. The difference in plots is most prominent in the range of VP = 3 to 5 km=s (or VS ~ 1:25 to 2:9 km/s), where our refraction VS is lower by a few tenths of a kilometer per second from VS based on direct measurements. Our new VS - VP curve may be useful for modeling the lower limit of VS from a VP model in calculating strong motions from scenario earthquakes.

Patterns of seed bank and vegetation diversity along a tidal freshwater river.

PubMed

Elsey-Quirk, Tracy; Leck, Mary Allessio

2015-12-01

Species richness and diversity may increase with spatial scale related to increased area and heterogeneity of habitat. Yet, in bidirectional hydrologically connected tidal ecosystems, secondary dispersal via hydrochory has the potential to homogenize seed banks, and both life history characteristics and tolerances to environmental conditions influence the composition of plant communities. How species richness, diversity, and composition of seed banks and vegetation change along environmental gradients and at different spatial scales is not well understood. We explored the relationships of seed bank and vegetation diversity across 135 plots along a tidal freshwater river in the Delaware Estuary, USA. Species richness and diversity were partitioned across three hierarchical spatial scales: individual plots, transects perpendicular to the tidal channel, and river kilometers. Community structure was also examined as it related to distance from the tidal channel and location along the tidal river. Species richness was 89 in the seed bank and 54 in the vegetation. Species-area relationships revealed that species richness reached a near maximum asymptote inland (20 m from channel) for the seed bank and at the edge (0 m) for the vegetation. Rare occurrences of species in the seed bank and vegetation were greatest 5 m from the channel edge. As spatial scale increased, seed bank richness increased, associated with the progressive accumulation of species. Seed bank diversity, however, was maximized within small plot areas and along the river. Diversity of the vegetation was maximized locally due to the abundance of a few common species. These findings suggest that suites of common species contributed to high localized vegetation diversity, yet large spatial scales maximized the number and diversity of species in the seed bank and vegetation through rare encounters, as well as the complexity of the landscape. © 2015 Botanical Society of America.

Lead isotope data bank; 2,624 samples and analyses cited

USGS Publications Warehouse

Doe, Bruce R.

1976-01-01

The Lead Isotope Data Bank (LIDB) was initiated to facilitate plotting data. Therefore, the Bank reflects data most often used in plotting rather than comprises a comprehensive tabulation of lead isotope data. Up until now, plotting was done using card decks processed by computer with tapes plotted by a Gerber plotter and more recently a CRT using a batch mode. Lack of a uniform format for sample identification was not a great impediment. With increase in the size of the bank, hand sorting is becoming prohibitive and ·plans are underway to put the bank into a uniform format on DISK with a card backup so that it may be accessed by use of IRIS on the DECK 10 computer at the U.S.G.S. facility in Denver. Plots will be constructed on a CRT. Entry of the bank into the IRIS accessing program is scheduled for completion in FY 1976

Optimum nonparametric estimation of population density based on ordered distances

USGS Publications Warehouse

Patil, S.A.; Kovner, J.L.; Burnham, Kenneth P.

1982-01-01

The asymptotic mean and error mean square are determined for the nonparametric estimator of plant density by distance sampling proposed by Patil, Burnham and Kovner (1979, Biometrics 35, 597-604. On the basis of these formulae, a bias-reduced version of this estimator is given, and its specific form is determined which gives minimum mean square error under varying assumptions about the true probability density function of the sampled data. Extension is given to line-transect sampling.

Effect of Proximity to a Cattle Feedlot on Escherichia coli O157:H7 Contamination of Leafy Greens and Evaluation of the Potential for Airborne Transmission

PubMed Central

Wells, James E.; Bono, James L.; Woodbury, Bryan L.; Kalchayanand, Norasak; Norman, Keri N.; Suslow, Trevor V.; López-Velasco, Gabriela; Millner, Patricia D.

2014-01-01

The impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance). Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased. Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur. Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust. Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination. PMID:25452286

Statistical Strategy for Inventorying and Monitoring the Ecosystem Resources of the State of Jalisco at Multiple Scales and Resolution Levels

Treesearch

Robin M. Reich; Hans T. Schreuder

2006-01-01

The sampling strategy involving both statistical and in-place inventory information is presented for the natural resources project of the Green Belt area (Centuron Verde) in the Mexican state of Jalisco. The sampling designs used were a grid based ground sample of a 90x90 m plot and a two-stage stratified sample of 30 x 30 m plots. The data collected were used to...

The pros and cons of funnel plots as an aid to risk communication and patient decision making.

PubMed

Rakow, Tim; Wright, Rebecca J; Spiegelhalter, David J; Bull, Catherine

2015-05-01

Funnel plots, which simultaneously display a sample statistic and the corresponding sample size for multiple cases, have a range of applications. In medicine, they are used to display treatment outcome rates and caseload volume by institution, which can inform strategic decisions about health care delivery. We investigated lay people's understanding of such plots and explored their suitability as an aid to individual treatment decisions. In two studies, 172 participants answered objective questions about funnel plots representing the surgical outcomes (survival or mortality rates) of institutions varying in caseload, and indicated their preferred institutions. Accuracy for extracting objective information was high, unless question phrasing was inconsistent with the plot's survival/mortality framing, or participants had low numeracy levels. Participants integrated caseload-volume and outcome-rate data when forming preferences, but were influenced by reference lines on the plot to make inappropriate discriminations between institutions with similar outcome rates. With careful choice of accompanying language, funnel plots can be readily understood and are therefore a useful tool for communicating risk. However, they are less effective as a decision aid for individual patient's treatment decisions, and we recommend refinements to the standard presentation of the plots if they are to be used for that purpose. © 2014 The British Psychological Society.

Developing effective sampling designs for monitoring natural resources in Alaskan national parks: an example using simulations and vegetation data

USGS Publications Warehouse

Thompson, William L.; Miller, Amy E.; Mortenson, Dorothy C.; Woodward, Andrea

2011-01-01

Monitoring natural resources in Alaskan national parks is challenging because of their remoteness, limited accessibility, and high sampling costs. We describe an iterative, three-phased process for developing sampling designs based on our efforts to establish a vegetation monitoring program in southwest Alaska. In the first phase, we defined a sampling frame based on land ownership and specific vegetated habitats within the park boundaries and used Path Distance analysis tools to create a GIS layer that delineated portions of each park that could be feasibly accessed for ground sampling. In the second phase, we used simulations based on landcover maps to identify size and configuration of the ground sampling units (single plots or grids of plots) and to refine areas to be potentially sampled. In the third phase, we used a second set of simulations to estimate sample size and sampling frequency required to have a reasonable chance of detecting a minimum trend in vegetation cover for a specified time period and level of statistical confidence. Results of the first set of simulations indicated that a spatially balanced random sample of single plots from the most common landcover types yielded the most efficient sampling scheme. Results of the second set of simulations were compared with field data and indicated that we should be able to detect at least a 25% change in vegetation attributes over 31. years by sampling 8 or more plots per year every five years in focal landcover types. This approach would be especially useful in situations where ground sampling is restricted by access.

Quantification of extraradical soil mycelium and ectomycorrhizas of Boletus edulis in a Scots pine forest with variable sporocarp productivity.

PubMed

De la Varga, Herminia; Agueda, Beatriz; Martínez-Peña, Fernando; Parladé, Javier; Pera, Joan

2012-01-01

The availability of most edible ectomycorrhizal mushrooms depends on their natural fructification. Sporocarp formation of these fungi is linked to habitat characteristics and climate conditions, but these data alone do not explain all the trends of fungal fruiting and dynamics. It could be hypothesized that the amount of soil mycelia could also be related to the production of carpophores. Soil samples (five cylinders of 250 cm(3) per plot) were taken monthly, from September to November, in five fenced permanent plots (5 × 5 m) in Pinar Grande (Soria, Spain), a Pinus sylvestris stand situated in the north of the Sistema Ibérico mountain range. Plots were chosen to establish a gradient of Boletus edulis productivity from 0 to 38.5 kg/ha year, according to the mean fresh weight of sporocarps collected during the last 10 years. B. edulis ectomycorrhizal root tips were identified in each soil sample according to its morphology and counted. DNA extractions were performed with the PowerSoil(TM) DNA Isolation Kit and quantification of extraradical soil mycelium by real-time polymerase chain reaction using specific primers and a TaqMan® probe. The concentration of soil mycelium of B. edulis (mg mycelium/g soil) did not differ significantly between plots (p = 0.1397), and sampling time (p = 0.7643) within the fructification period. The number of mycorrhizal short roots per soil volume showed significant differences between the plots (p = 0.0050) and the three sampling times (p < 0.0001). No significant correlation between the number of mycorrhizas and the productivity of the plot (kg of B. edulis/ha year) was detected (p = 0.615). A statistically significant positive correlation (p = 0.0481) was detected between the concentration of mycelia of B. edulis in the soil samples and the presence of short roots mycorrhizal with B. edulis in these samples. The productivity of the plots, in terms of sporocarps produced during the last 10 years, was not correlated either with the concentration of soil mycelium or with the presence or abundance of ectomycorrhizas.

Plastic pollution in the South Pacific subtropical gyre.

PubMed

Eriksen, Marcus; Maximenko, Nikolai; Thiel, Martin; Cummins, Anna; Lattin, Gwen; Wilson, Stiv; Hafner, Jan; Zellers, Ann; Rifman, Samuel

2013-03-15

Plastic marine pollution in the open ocean of the southern hemisphere is largely undocumented. Here, we report the result of a (4489 km) 2424 nautical mile transect through the South Pacific subtropical gyre, carried out in March-April 2011. Neuston samples were collected at 48 sites, averaging 50 nautical miles apart, using a manta trawl lined with a 333 μm mesh. The transect bisected a predicted accumulation zone associated with the convergence of surface currents, driven by local winds. The results show an increase in surface abundance of plastic pollution as we neared the center and decrease as we moved away, verifying the presence of a garbage patch. The average abundance and mass was 26,898 particles km(-2) and 70.96 g km(-2), respectively. 88.8% of the plastic pollution was found in the middle third of the samples with the highest value of 396,342 particles km(-2) occurring near the center of the predicted accumulation zone. Copyright © 2013 Elsevier Ltd. All rights reserved.

Confidence limits for contribution plots in multivariate statistical process control using bootstrap estimates.

PubMed

Babamoradi, Hamid; van den Berg, Frans; Rinnan, Åsmund

2016-02-18

In Multivariate Statistical Process Control, when a fault is expected or detected in the process, contribution plots are essential for operators and optimization engineers in identifying those process variables that were affected by or might be the cause of the fault. The traditional way of interpreting a contribution plot is to examine the largest contributing process variables as the most probable faulty ones. This might result in false readings purely due to the differences in natural variation, measurement uncertainties, etc. It is more reasonable to compare variable contributions for new process runs with historical results achieved under Normal Operating Conditions, where confidence limits for contribution plots estimated from training data are used to judge new production runs. Asymptotic methods cannot provide confidence limits for contribution plots, leaving re-sampling methods as the only option. We suggest bootstrap re-sampling to build confidence limits for all contribution plots in online PCA-based MSPC. The new strategy to estimate CLs is compared to the previously reported CLs for contribution plots. An industrial batch process dataset was used to illustrate the concepts. Copyright © 2016 Elsevier B.V. All rights reserved.

Geochemical and Morphologic Evolution of Soil-Covered Hillslopes in the Feather River Basin, California: Responses to Channel Incision

NASA Astrophysics Data System (ADS)

Weinman, B.; Yoo, K.; Mudd, S. M.; Hurst, M. D.; Mayer, K.; Maher, K.

2009-12-01

Tectonically driven changes in channel incision rates lead to changes in hillslope erosion rates that propagate upslope. In an effort to understand how these changes affect soil geochemistry, this study theoretically and empirically integrates sediment transport and chemical weathering. Here, we focus on a tributary basin of the Middle Folk Feather River (FR) in Sierra Nevada, California. This basin is adjusting to an increase in main stem channel incision that has resulted in rapidly eroding, steep hillslopes near the main stem channel and gentler, more slowly eroding slopes further upstream. To constrain how geomorphic signals (i.e., knickpoint) propagate upslope and affect soil geochemistry, soils were sampled in July 2009 along three hillslope transects within the FR basin: transect POMD (40% slope at 780m elevation), FTA (70% slope at 680m elevation), and BRC (90% slope at 630m elevation). To capture and bracket a coupled change in soil geochemistry upslope, transects were specifically chosen so that POMD is downstream of the knickpoint of the main channel, FTA in a transitional region, and BRC upstream of the knickpoint. Along each ~50 m transect, soil pits were dug <10 m apart of each other to depths of about 1m. CRN samples were collected from the upper saprolite and undisturbed B horizons to determine the soil production rates. For constraining soil mixing, sediment ages, and chemical weathering, OSL and geochemistry samples were collected every ~10 cm in the A, B, and saprolite horizons. Judging from the soil color, the abundances of pedogenic iron oxides systematically are greater in the less steep hillslopes. This is consistent with a preliminary view that the soils have briefer residence times in the steeper hillslopes, which have greater rates of channel incision at their lower boundaries. One contrast to our expectations, however, was that the soils were not consistently thicker in the gentler hillslopes, which presumably undergo reduced rates of soil erosion. Additionally, within each hillslope, soil thicknesses were largely constant, ~50-70 cm thick. Therefore, tree throw, which appears to be dominant soil production mechanism at the site, may be capable of buffering soil thickness against the variation of soil erosion rate. While we are still in the preliminary stages of the OSL and CRN work, transect profiles of major oxide elements Si, Al, Fe, Ca, Mg, Na, K, P, and Mn versus potentially immobile elements such as Zr and Ti in the soils are used to infer how channel incision affects soil geochemistry in the three hillslopes. In the future, these results will be coupled with LiDAR, OSL, CRN, and pore-water chemistry work for a more holistic view of how the morphology and geochemistry of hillslopes evolve together in their responses to tectonic forcing.

Forest health monitoring in New England: 1990 annual report

Treesearch

Robert T. Brooks; David R. Dickson; William B. Burkman; Imants Millers; Margaret Miller-Weeks; Ellen Cooter; Luther Smith; Luther Smith

1992-01-01

The USDA Forest Service, in cooperation with the U.S. Environmental Protection Agency and the New England State Forestry Agencies initiated field sampling for the Forest Health Monitoring program in 1990. Two hundred and sixty-three permanent sample plots were established. Measurements were taken to characterize the physical conditions of the plots. This publication...

Study of the Effect on Ionic Conductivity and Structral Morphology of the SR Doped Lanthanum Gallate Solid Electrolyte

NASA Astrophysics Data System (ADS)

Sood, Kapil; Singh, K.; Pandey, O. P.

2013-07-01

In the present study, lanthanum gallate and Sr-doped lanthanum gallate samples were prepared by conventional solid state reaction method. The phase conformation has been performed by using X-ray diffraction (XRD) study. The elemental composition has been confirmed using energy dispersive spectroscopy (EDS) analysis. Ac conductivity of the samples has been measured in the frequency range 0.1-106 Hz and from 50-800 °C. The impedance plots among real and complex impedances at particular temperature have been discussed. The behavior shows the effect of bulk and grain boundary effects of the doped sample. The impedance plots with frequency have been analyzed. The plots have been well fitted to equivalent circuit model. The conductivity shows the Arrhenius type of behavior. The activation energy has been calculated from the plots and represents that the conductivity through the material is mainly ionic. The structural morphology of the samples has been investigated using scanning electron microscope (SEM). The micrograph shows that the porosity and grain size both decreases with Sr-doping.

Integrated biochemical, molecular genetic, and bioacoustical analysis of mesoscale variability of the euphausiid Nematoscelis difficilis in the California Current

NASA Astrophysics Data System (ADS)

Bucklin, Ann; Wiebe, Peter H.; Smolenack, Sara B.; Copley, Nancy J.; Clarke, M. Elizabeth

2002-03-01

Integrated assessment of the euphausiid Nematoscelis difficilis (Crustacea; Euphausiacea) and the zooplankton assemblage of the California Current was designed to investigate individual, population, and community responses to mesoscale variability in biological and physical characters of the ocean. Zooplankton samples and observational data were collected along a cross-shelf transect of the California Current in association with the California Cooperative Fisheries Investigations (CalCOFI) Survey during October 1996. The transect crossed three domains defined by temperature and salinity: nearshore, mid-Current, and offshore. Individual N. difficilis differed in physiological condition along the transect, with higher size-corrected concentrations of four central metabolic enzymes (citrate synthetase, hexokinase, lactate dehydrogenase (LDH), and phosphoglucose isomerase (PGI)) for euphausiids collected in nearshore waters than in mid-Current and offshore waters. There was little variation in the DNA sequences of the genes encoding PGI and LDH (all DNA changes were either silent or heterozygous base substitutions), suggesting that differences in enzyme concentration did not result from underlying molecular genetic variation. The population genetic makeup of N. difficilis varied from sample to sample based on haplotype frequencies of mitochondrial cytochrome oxidase I (mtCOI; P=0.029). There were significant differences between pooled nearshore and offshore samples, based on allele frequencies at two sites of common substitutions in the mtCOI sequence ( P=0.020 and 0.026). Silhouette and bioacoustical backscattering measurements of the zooplankton assemblage of the top 100 m showed marked diel vertical migration of the scattering layer, of which euphausiids were a small but significant fraction. The biochemical and molecular assays are used as indices of complex physiological (i.e., growth and condition) and genetic (i.e., mortality) processes; the bioacoustical observations provide insight into the ecosystem context for the single-species measurements. All data are intended for integration into predictive models of secondary production and biomass concentration in the ocean.

Opinions on Suicide and Perceived Barriers to Care in a Sample of United States Marine Non-Commissioned Officers: Implications for Future Frontline Supervisors’ Suicide Prevention Training Programs

DTIC Science & Technology

2013-11-06

the Scree plot (Figure 3) and the analysis was repeated saving these four factors. The Kaiser - Meyer - Olkin measure of sampling adequacy was .95...the Scree plot (Figure 4) and the analysis was repeated saving these three factors. The Kaiser - Meyer - Olkin measure of sampling adequacy was .90, above

The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography.

PubMed

Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P C

2016-07-01

Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Randomized clinical trial of stapler versus clamp-crushing transection in elective liver resection.

PubMed

Rahbari, N N; Elbers, H; Koch, M; Vogler, P; Striebel, F; Bruckner, T; Mehrabi, A; Schemmer, P; Büchler, M W; Weitz, J

2014-02-01

Various devices have been developed to facilitate liver transection and reduce blood loss in liver resections. None of these has proven superiority compared with the classical clamp-crushing technique. This randomized clinical trial compared the effectiveness and safety of stapler transection with that of clamp-crushing during open liver resection. Patients admitted for elective open liver resection between January 2010 and October 2011 were assigned randomly to stapler transection or the clamp-crushing technique. The primary endpoint was the total amount of intraoperative blood loss. Secondary endpoints included transection time, duration of operation, complication rates and resection margins. A total of 130 patients were enrolled, 65 to clamp-crushing and 65 to stapler transection. There was no difference between groups in total intraoperative blood loss: median (i.q.r.) 1050 (525-1650) versus 925 (450-1425) ml respectively (P = 0·279). The difference in total intraoperative blood loss normalized to the transection surface area was not statistically significant (P = 0·092). Blood loss during parenchymal transection was significantly lower in the stapler transection group (P = 0·002), as were the parenchymal transection time (mean(s.d.) 30(21) versus 9(7) min for clamp-crushing and stapler transection groups respectively; P < 0·001) and total duration of operation (mean(s.d.) 221(86) versus 190(85) min; P = 0·047). There were no significant differences in postoperative morbidity (P = 0·863) or mortality (P = 0·684) between groups. Stapler transection is a safe technique but does not reduce intraoperative blood loss in elective liver resection compared with the clamp-crushing technique. NCT01049607 (http://www.clinicaltrials.gov). © 2014 BJS Society Ltd. Published by John Wiley & Sons Ltd.

A gradient model of vegetation and climate utilizing NOAA satellite imagery. Phase 1: Texas transect

NASA Technical Reports Server (NTRS)

Greegor, D. H.; Norwine, J.

1981-01-01

A new experimental climatological model/variable termed the sponge, a measure of moisture availability based on daily temperature maxima and minima and precipitation, is tested for potential biogeographic, ecological, and agro-climatological applications. Results, depicted in tabular and graphic from, suggest that, as a generalized climatic index, sponge's simplicity and sensitivity make particularly appropriate for trans-regional biogeographic studies (e.g., large-area and global vegetation monitoring). The feasibility of utilizing NOAA/AVHRR data for vegetation classification was investigated and a vegetation gradient model that utilizes sponge, and AVHRR pixel data (channels 1 and 2) were obtained for 12 locations. The normalized difference values for the AVHRR data when plotted against vegetation characteristics (biomass, net productivity, leaf area) and sponge values suggest that a multivariate gradient model incorporating AVHRR and sponge data may indeed be useful in global vegetation stratification and monitoring.

A gradient model of vegetation and climate utilizing NOAA satellite imagery. Phase 1: Texas transect

NASA Technical Reports Server (NTRS)

Greegor, D.; Norwine, J. (Principal Investigator)

1981-01-01

A climatological model/variable termed the sponge (a measure of moisture availability based on daily temperature maxima and minima, and precipitation) was tested for potential biogeograhic, ecological, and agro-climatological applications. Results, depicted in tabular and graphic form, suggest that, as generalized climatic index, sponge is particularly appropriate for large-area and global vegetation monitoring. The feasibility of utilizing NOAA/AVHRR data for vegetation classification was investigated and a vegetation gradient model that utilizes sponge and AVHRR data was initiated. Along an east-west Texas gradient, vegetation, sponge, and AVHRR pixel data (channels 1 and 2) were obtained for 12 locations. The normalized difference values for the AVHRR data when plotted against vegetation characteristics (biomass, net productivity, leaf area) and sponge values along the Texas gradient suggest that a multivariate gradient model incorporating AVHRR and sponge data may indeed be useful in global vegetation stratification and monitoring.

Termite assemblages from oil palm agroecosystems across Riau Province, Sumatra, Indonesia

NASA Astrophysics Data System (ADS)

Saputra, Andi; Jalaludin, Nur-Atiqah; Hazmi, Izfa Riza; Rahim, Faszly

2016-11-01

Termite survey was conducted at six oil palm agroecosystem sites in Riau Province, Sumatra, Indonesia to document species richness across the sites. Six sites were surveyed by using continuous transect representing gradients of oil palm landuse across Indragiri Hulu to Bengkalis District since February 5th, 2015 until May 21st, 2015. Termites were sampled by modified transect protocols (100 m × 4 m × 10 cm). A total of 23 species belonging to two families and five subfamilies were collected. The termite assemblage was dominated by wood-feeding termites. The major family collected was Rhinotermitidae which included some pest species, such as Coptotermes curvignathus, C. sepangensis, C. kalshoveni, Schedorhinotermes malaccensis, S. medioobscurus, S. brevialatus, and S. javanicus.

Towards the harmonization between National Forest Inventory and Forest Condition Monitoring. Consistency of plot allocation and effect of tree selection methods on sample statistics in Italy.

PubMed

Gasparini, Patrizia; Di Cosmo, Lucio; Cenni, Enrico; Pompei, Enrico; Ferretti, Marco

2013-07-01

In the frame of a process aiming at harmonizing National Forest Inventory (NFI) and ICP Forests Level I Forest Condition Monitoring (FCM) in Italy, we investigated (a) the long-term consistency between FCM sample points (a subsample of the first NFI, 1985, NFI_1) and recent forest area estimates (after the second NFI, 2005, NFI_2) and (b) the effect of tree selection method (tree-based or plot-based) on sample composition and defoliation statistics. The two investigations were carried out on 261 and 252 FCM sites, respectively. Results show that some individual forest categories (larch and stone pine, Norway spruce, other coniferous, beech, temperate oaks and cork oak forests) are over-represented and others (hornbeam and hophornbeam, other deciduous broadleaved and holm oak forests) are under-represented in the FCM sample. This is probably due to a change in forest cover, which has increased by 1,559,200 ha from 1985 to 2005. In case of shift from a tree-based to a plot-based selection method, 3,130 (46.7%) of the original 6,703 sample trees will be abandoned, and 1,473 new trees will be selected. The balance between exclusion of former sample trees and inclusion of new ones will be particularly unfavourable for conifers (with only 16.4% of excluded trees replaced by new ones) and less for deciduous broadleaves (with 63.5% of excluded trees replaced). The total number of tree species surveyed will not be impacted, while the number of trees per species will, and the resulting (plot-based) sample composition will have a much larger frequency of deciduous broadleaved trees. The newly selected trees have-in general-smaller diameter at breast height (DBH) and defoliation scores. Given the larger rate of turnover, the deciduous broadleaved part of the sample will be more impacted. Our results suggest that both a revision of FCM network to account for forest area change and a plot-based approach to permit statistical inference and avoid bias in the tree sample composition in terms of DBH (and likely age and structure) are desirable in Italy. As the adoption of a plot-based approach will keep a large share of the trees formerly selected, direct tree-by-tree comparison will remain possible, thus limiting the impact on the time series comparability. In addition, the plot-based design will favour the integration with NFI_2.

High spatial variability in biogeochemical rates and microbial communities across Louisiana salt marsh landscapes

NASA Astrophysics Data System (ADS)

Roberts, B. J.; Chelsky, A.; Bernhard, A. E.; Giblin, A. E.

2017-12-01

Salt marshes are important sites for retention and transformation of carbon and nutrients. Much of our current marsh biogeochemistry knowledge is based on sampling at times and in locations that are convenient, most often vegetated marsh platforms during low tide. Wetland loss rates are high in many coastal regions including Louisiana which has the highest loss rates in the US. This loss not only reduces total marsh area but also changes the relative allocation of subhabitats in the remaining marsh. Climate and other anthropogenic changes lead to further changes including inundation patterns, redox conditions, salinity regimes, and shifts in vegetation patterns across marsh landscapes. We present results from a series of studies examining biogeochemical rates, microbial communities, and soil properties along multiple edge to interior transects within Spartina alterniflora across the Louisiana coast; between expanding patches of Avicennia germinans and adjacent S. alterniflora marshes; in soils associated with the four most common Louisiana salt marsh plants species; and across six different marsh subhabitats. Spartina alterniflora marsh biogeochemistry and microbial populations display high spatial variability related to variability in soil properties which appear to be, at least in part, regulated by differences in elevation, hydrology, and redox conditions. Differences in rates between soils associated with different vegetation types were also related to soil properties with S. alterniflora soils often yielding the lowest rates. Biogeochemical process rates vary significantly across marsh subhabitats with individual process rates differing in their hotspot habitat(s) across the marsh. Distinct spatial patterns may influence the roles that marshes play in retaining and transforming nutrients in coastal regions and highlight the importance of incorporating spatial sampling when scaling up plot level measurements to landscape or regional scales.

The same but different: equally megadiverse but taxonomically variant spider communities along an elevational gradient

NASA Astrophysics Data System (ADS)

Malumbres-Olarte, Jagoba; Crespo, Luís; Cardoso, Pedro; Szűts, Tamás; Fannes, Wouter; Pape, Thomas; Scharff, Nikolaj

2018-04-01

Spatial variation in biodiversity is one of the key pieces of information for the delimitation and prioritisation of protected areas. This information is especially important when the protected area includes different climatic and habitat conditions and communities, such as those along elevational gradients. Here we test whether the megadiverse communities of spiders along an elevational gradient change according to two diversity models - a monotonic decrease or a hump-shaped pattern in species richness. We also measure compositional variation along and within elevations, and test the role of the preference of microhabitat (vegetation strata) and the functional (guild) structure of species in the changes. We sampled multiple spider communities using standardised and optimised sampling in three forest types, each at a different elevation along a climatic gradient. The elevational transects were at increasing horizontal distances (between 0.1 and 175 km) in the Udzungwa Mountains, Eastern Arc Mountains, Tanzania. The number of species was similar between plots and forest types, and therefore the pattern did not match either diversity model. However, species composition changed significantly with a gradual change along elevations. Although the number of species per microhabitat and guild also remained similar across elevations, the number of individuals varied, e.g. at higher elevations low canopy vegetation was inhabited by more spiders, and the spiders belonging to guilds that typically use this microhabitat were more abundant. Our findings reflex the complex effects of habitat-microhabitat interactions on spider communities at the individual, species and guild levels. If we aim to understand and conserve some of the most diverse communities in the world, researchers and managers may need to place more attention to small scale and microhabitat characteristics upon which communities depend.

Preliminary Results of Double-Sample Forest Inventory of Pine and Mixed Stands with High- and Low-Density LiDAR

Treesearch

Robert C. Parker; Patrick A. Glass

2004-01-01

LiDAR data (0.5 and 1 m postings) were used in a double-sample forest inventory on the Lee Experimental Forest, Louisiana. Phase 2 plots were established with DGPS. Tree d.b.h. (> 4.5 inches) and two sample heights were measured on every 10 th plot of the Phase 1 sample. Volume was computed for natural and planted pine and mixed hardwood species. LiDAR trees were...

3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

USGS Publications Warehouse

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river.

Statistical Algorithms for Designing Geophysical Surveys to Detect UXO Target Areas

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

O'Brien, Robert F.; Carlson, Deborah K.; Gilbert, Richard O.

2005-07-29

The U.S. Department of Defense is in the process of assessing and remediating closed, transferred, and transferring military training ranges across the United States. Many of these sites have areas that are known to contain unexploded ordnance (UXO). Other sites or portions of sites are not expected to contain UXO, but some verification of this expectation using geophysical surveys is needed. Many sites are so large that it is often impractical and/or cost prohibitive to perform surveys over 100% of the site. In that case, it is particularly important to be explicit about the performance required of the survey. Thismore » article presents the statistical algorithms developed to support the design of geophysical surveys along transects (swaths) to find target areas (TAs) of anomalous geophysical readings that may indicate the presence of UXO. The algorithms described here determine 1) the spacing between transects that should be used for the surveys to achieve a specified probability of traversing the TA, 2) the probability of both traversing and detecting a TA of anomalous geophysical readings when the spatial density of anomalies within the TA is either uniform (unchanging over space) or has a bivariate normal distribution, and 3) the probability that a TA exists when it was not found by surveying along transects. These algorithms have been implemented in the Visual Sample Plan (VSP) software to develop cost-effective transect survey designs that meet performance objectives.« less

Statistical Algorithms for Designing Geophysical Surveys to Detect UXO Target Areas

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

O'Brien, Robert F.; Carlson, Deborah K.; Gilbert, Richard O.

2005-07-28

The U.S. Department of Defense is in the process of assessing and remediating closed, transferred, and transferring military training ranges across the United States. Many of these sites have areas that are known to contain unexploded ordnance (UXO). Other sites or portions of sites are not expected to contain UXO, but some verification of this expectation using geophysical surveys is needed. Many sites are so large that it is often impractical and/or cost prohibitive to perform surveys over 100% of the site. In such cases, it is particularly important to be explicit about the performance required of the surveys. Thismore » article presents the statistical algorithms developed to support the design of geophysical surveys along transects (swaths) to find target areas (TAs) of anomalous geophysical readings that may indicate the presence of UXO. The algorithms described here determine (1) the spacing between transects that should be used for the surveys to achieve a specified probability of traversing the TA, (2) the probability of both traversing and detecting a TA of anomalous geophysical readings when the spatial density of anomalies within the TA is either uniform (unchanging over space) or has a bivariate normal distribution, and (3) the probability that a TA exists when it was not found by surveying along transects. These algorithms have been implemented in the Visual Sample Plan (VSP) software to develop cost-effective transect survey designs that meet performance objectives.« less

Permanent-plot procedures for silvicultural and yield research.

Treesearch

Robert O. Curtis; David D. Marshall

2005-01-01

This paper reviews purposes and procedures for establishing and maintaining permanent plots for silvicultural and yield research, sampling and plot design, common errors, and procedures for measuring and recording data. It is a revision and update of a 1983 publication. Although some details are specific to coastal Pacific Northwest conditions, most of the material is...

National FIA plot intensification procedure report

Treesearch

Jock A. Blackard; Paul L. Patterson

2014-01-01

The Forest Inventory and Analysis (FIA) program of the U.S. Forest Service (USFS) measures a spatially distributed base grid of forest inventory plots across the United States. The sampling intensity of plots may be increased in some regions when warranted by specific inventory objectives. Several intensification methods have been developed within FIA and USFS National...

Bacterial, Fungal, and Actinomycete Populations in Soils Receiving Repeated Applications of 2,4-Dichlorophenoxyacetic Acid and Trifluralin 1

PubMed Central

Breazeale, F. W.; Camper, N. D.

1970-01-01

Soil samples were collected from an untreated plot and plots receiving repeated applications of 2,4-dichlorophenoxyacetic acid (2,4-D) and α,α,α-trifluoro-2, 6-dinitro-N,N-dipropyl-p-toluidine (trifluralin); they were then plated on media specific for bacteria, fungi, and actinomycetes. The actinomycete colony count in the trifluralin-treated plot was greater than the control, but the same as the control in the 2,4-D-treated plot. The bacterial count was lower in both treated plots. Fungal colonies in the trifluralin-treated plots were greater than the control, but not different from the control in the 2,4-D-treated plot. PMID:5437308

Round versus rectangular: Does the plot shape matter?

NASA Astrophysics Data System (ADS)

Iserloh, Thomas; Bäthke, Lars; Ries, Johannes B.

2016-04-01

Field rainfall simulators are designed to study soil erosion processes and provide urgently needed data for various geomorphological, hydrological and pedological issues. Due to the different conditions and technologies applied, there are several methodological aspects under review of the scientific community, particularly concerning design, procedures and conditions of measurement for infiltration, runoff and soil erosion. Extensive discussions at the Rainfall Simulator Workshop 2011 in Trier and the Splinter Meeting at EGU 2013 "Rainfall simulation: Big steps forward!" lead to the opinion that the rectangular shape is the more suitable plot shape compared to the round plot. A horizontally edging Gerlach trough is installed for sample collection without forming unnatural necks as is found at round or triangle plots. Since most research groups did and currently do work with round plots at the point scale (<1m²), a precise analysis of the differences between the output of round and square plots are necessary. Our hypotheses are: - Round plot shapes disturb surface runoff, unnatural fluvial dynamics for the given plot size such as pool development especially directly at the plot's outlet occur. - A square plot shape prevent these problems. A first comparison between round and rectangular plots (Iserloh et al., 2015) indicates that the rectangular plot could indeed be the more suitable, but the rather ambiguous results make a more elaborate test setup necessary. The laboratory test setup includes the two plot shapes (round, square), a standardised silty substrate and three inclinations (2°, 6°, 12°). The analysis of the laboratory test provide results on the best performance concerning undisturbed surface runoff and soil/water sampling at the plot's outlet. The analysis of the plot shape concerning its influence on runoff and erosion shows that clear methodological standards are necessary in order to make rainfall simulation experiments comparable. Reference: Iserloh, T., Pegoraro, D., Schlösser, A., Thesing, H., Seeger, M., Ries, J.B. (2015): Rainfall simulation experiments: Influence of water temperature, water quality and plot design on soil erosion and runoff. Geophysical Research Abstracts, Vol. 17, EGU2015-5817.

Grays Harbor and Chehalis River Improvements to Navigation Environmental Studies. Grays Harbor Ocean Disposal Study. Literature Review and Preliminary Benthic Sampling,

DTIC Science & Technology

1980-05-01

transects extending approximately 16 kilometers from the mouth of Grays Harbor. Sub- samples were taken for grain size analysis and wood content. The...samples were thert was".d on a 1.0 mm screen to separate benthic organisms from non-living materials. Consideration of the grain size analysis ...Nutrients 17 B. Field Study 18 Methods 18 Grain Size Analysis 18 Wood Analysis 21 Wood Fragments 21 Sediment Types 21 Discussion 24 IV. BIOLOGICAL

Experimental manipulations of snow-depth: Effects on nutrient content of caribou forage

USGS Publications Warehouse

Walsh, Noreen E.; McCabe, Thomas R.; Welker, J.M.; Parsons, A.N.

1997-01-01

We investigated the potential effects of global climate change on arctic tundra vegetation used as caribou forage. A total of 96 experimental plots was established at six sites on the coastal plain of the Arctic National Wildlife Refuge, Alaska, in 1993 and 1994. We erected snow-fences to increase the amount of snow deposition, and therefore delay the date of the snowmelt on 48 plots (referred to as increased snow/late melting plots). We used black mesh netting on the surface of the snow to increase the rate of melting on 24 plots; the remaining 24 plots served as controls. In July 1994, we collected green leaves from Eriophorum vaginatum, Salix planifolia, and Betula nana and analysed these samples for total carbon and total nitrogen content. Ratios of carbon to nitrogen differed among treatments for all three species. Generally, C:N ratios for B. nana and E. vaginatum on increased snow/late melting plots were lower than on control plots. C:N ratios for S. planifolia on increased snow/late melting plots did not differ from controls, but were lower than on plots which started to melt early. These results may be due to the timing of nitrogen translocation from leaf and stem tissue into storage organs, or due to an increase in available nitrogen input to the system. Further sampling is needed to adequately determine the mechanism responsible for increased nitrogen content of caribou forage in areas with increased amount of snow and delayed snowmelt. ?? 1997 Blackwell Science Ltd.

Vegetation responses to natural regulation of elk in Rocky Mountain National Park

USGS Publications Warehouse

Zeigenfuss, Linda C.; Singer, Francis J.; Bowden, David

1999-01-01

Some grazing-induced responses were detected. Grazing-resistant species such as sedges (native), timothy (exotic), and club mosses increased and the amount of bare ground increased on some grazed sites. However, the changes within this sampling program alone were not alarming. The amount of bare ground increase was minor (4%), and grass and shrub cover increased in the shrub plots. The inferential power ofthis sample design was limited to the study plots only. Other factors (climate change, succession) were not controlled for using fenced plots and the sensitivity ofthe methods and plots to detect change were limited. For example, the low number oftransects in willow was not adequate to monitor conditions on the entire winter range. Lacking controls, observed changes may have been due to other factors (climate trends, beaver dam abandonment, stream channel changes), not elk herbivory alone. We recommend using a new sampling design that would include controls, pretreatment data, random site selection, and much more replication.

Alternative sampling designs and estimators for annual surveys

Treesearch

Paul C. Van Deusen

2000-01-01

Annual forest inventory systems in the United States have generally converged on sampling designs that: (1) measure equal proportions of the total number of plots each year; and (2) call for the plots to be systematically dispersed. However, there will inevitably be a need to deviate from the basic design to respond to special requests, natural disasters, and budgetary...

On fixed-area plot sampling for downed coarse woody debris

Treesearch

Jeffrey H. Gove; Paul C. Van Deusen

2011-01-01

The use of fixed-area plots for sampling down coarse woody debris is reviewed. A set of clearly defined protocols for two previously described methods is established and a new method, which we call the 'sausage' method, is developed. All methods (protocols) are shown to be unbiased for volume estimation, but not necessarily for estimation of population...

Environmental persistence of the nucleopolyhedrosis virus of the gypsy moth, Lymantria dispar L

Treesearch

J.D. Podgwaite; Kathleen Stone Shields; R.T. Zerillo; R.B. Bruen

1979-01-01

A bioassay technique was used to estimate the concentrations of infectious gypsy moth nucleopolyhedrosis virus (NPV) that occur naturaIly in leaf, bark, litter, and soil samples taken from woodland plots in Connecticut and Pennsylvania. These concentrations were then compared to those in samples taken sequentially after treatment of these plots with NPV. Results...

The new Brazilian national forest inventory

Treesearch

Joberto V. de Freitas; Yeda M. M. de Oliveira; Doadi A. Brena; Guilherme L.A. Gomide; Jose Arimatea Silva; < i> et al< /i>

2009-01-01

The new Brazilian national forest inventory (NFI) is being planned to be carried out through five components: (1) general coordination, led by the Brazilian Forest Service; (2) vegetation mapping, which will serve as the basis for sample plot location; (3) field data collection; (4) landscape data collection of 10 x 10-km sample plots, based on high-resolution...

Nutrient availability at Mer Bleue bog measured by PRSTM probes

NASA Astrophysics Data System (ADS)

Wang, M.; Moore, T. R.; Talbot, J.

2015-12-01

Bogs, covering ~0.7 million km2 in Canada, store a large amount of C and N. As nutrient deficient ecosystems, it's critical to examine the nutrient availabilities and seasonal dynamics. We used Plant Root Simulators (PRSTM) at Mer Bleue bog to provide some baseline data on nutrient availability and its variability. In particular, we focused on ammonium, nitrate, phosphate, calcium, magnesium and potassium, iron, sulphate and aluminum. We placed PRS probes at a depth of 5 - 15 cm in pristine plots and plots with long term N, P and K fertilization for 4 weeks and determined the availability of these nutrients, from spring through to fall. Probes were also placed beneath the water table in hummock and hollow microtopography and along a transect including part of the bog which had been drained through the creation of a ditch 80 years ago. The result showed that there was limited available ammonium, nitrate and phosphate in the bog, the seasonal variation of nutrient availabilities probably due to mineralization, an increase in the availability of some nutrients between different water table depths or as a result of drainage, and the relative availability of nutrients compared to the input from fertilization. We suggest that PRS probes could be a useful tool to examine nutrient availability and dynamics in wetlands, with careful consideration of installing condition, for example, proper exposure period, depth relative to water table etc.

Comparison of transect sampling and object-oriented image classification methods of urbanizing catchments

NASA Astrophysics Data System (ADS)

Yang, Y.; Tenenbaum, D. E.

2009-12-01

The process of urbanization has major effects on both human and natural systems. In order to monitor these changes and better understand how urban ecological systems work, urban spatial structure and the variation needs to be first quantified at a fine scale. Because the land-use and land-cover (LULC) in urbanizing areas is highly heterogeneous, the classification of urbanizing environments is the most challenging field in remote sensing. Although a pixel-based method is a common way to do classification, the results are not good enough for many research objectives which require more accurate classification data in fine scales. Transect sampling and object-oriented classification methods are more appropriate for urbanizing areas. Tenenbaum used a transect sampling method using a computer-based facility within a widely available commercial GIS in the Glyndon Catchment and the Upper Baismans Run Catchment, Baltimore, Maryland. It was a two-tiered classification system, including a primary level (which includes 7 classes) and a secondary level (which includes 37 categories). The statistical information of LULC was collected. W. Zhou applied an object-oriented method at the parcel level in Gwynn’s Falls Watershed which includes the two previously mentioned catchments and six classes were extracted. The two urbanizing catchments are located in greater Baltimore, Maryland and drain into Chesapeake Bay. In this research, the two different methods are compared for 6 classes (woody, herbaceous, water, ground, pavement and structure). The comparison method uses the segments in the transect method to extract LULC information from the results of the object-oriented method. Classification results were compared in order to evaluate the difference between the two methods. The overall proportions of LULC classes from the two studies show that there is overestimation of structures in the object-oriented method. For the other five classes, the results from the two methods are similar, except for a difference in the proportions of the woody class. The segment to segment comparison shows that the resolution of the light detection and ranging (LIDAR) data used in the object-oriented method does affect the accuracy of the classification. Shadows of trees and structures are still a big problem in the object-oriented method. For classes that make up a small proportion of the catchments, such as water, neither method was capable of detecting them.

Scale and Sampling Effects on Floristic Quality

PubMed Central

2016-01-01

Floristic Quality Assessment (FQA) is increasingly influential for making land management decisions, for directing conservation policy, and for research. But, the basic ecological properties and limitations of its metrics are ill defined and not well understood–especially those related to sample methods and scale. Nested plot data from a remnant tallgrass prairie sampled annually over a 12-year period, were used to investigate FQA properties associated with species detection rates, species misidentification rates, sample year, and sample grain/area. Plot size had no apparent effect on Mean C (an area’s average Floristic Quality level), nor did species detection levels above 65% detection. Simulated species misidentifications only affected Mean C values at greater than 10% in large plots, when the replaced species were randomly drawn from the broader county-wide species pool. Finally, FQA values were stable over the 12-year study, meaning that there was no evidence that the metrics exhibit year effects. The FQA metric Mean C is demonstrated to be robust to varied sample methodologies related to sample intensity (plot size, species detection rate), as well as sample year. These results will make FQA measures even more appealing for informing land-use decisions, policy, and research for two reasons: 1) The sampling effort needed to generate accurate and consistent site assessments with FQA measures is shown to be far lower than what has previously been assumed, and 2) the stable properties and consistent performance of metrics with respect to sample methods will allow for a remarkable level of comparability of FQA values from different sites and datasets compared to other commonly used ecological metrics. PMID:27489959

The hexagon/panel system for selecting FIA plots under an annual inventory

Treesearch

Gary J. Brand; Mark D. Nelson; Daniel G. Wendt; Kevin K. Nimerfro

2000-01-01

Forest Inventory and Analysis (FIA) is changing to an annual nationwide forest inventory. This paper describes the sampling grid used to distribute FIA plots across the landscape and to allocate them to a particular measurement year. We also describe the integration of the F1A and Forest Health Monitoring (FHM) plot networks.

Effects of plot size on forest-type algorithm accuracy

Treesearch

James A. Westfall

2009-01-01

The Forest Inventory and Analysis (FIA) program utilizes an algorithm to consistently determine the forest type for forested conditions on sample plots. Forest type is determined from tree size and species information. Thus, the accuracy of results is often dependent on the number of trees present, which is highly correlated with plot area. This research examines the...

Adding uncertainty to forest inventory plot locations: effects on analyses using geospatial data

Treesearch

Alexia A. Sabor; Volker C. Radeloff; Ronald E. McRoberts; Murray Clayton; Susan I. Stewart

2007-01-01

The Forest Inventory and Analysis (FIA) program of the USDA Forest Service alters plot locations before releasing data to the public to ensure landowner confidentiality and sample integrity, but using data with altered plot locations in conjunction with other spatially explicit data layers produces analytical results with unknown amounts of error. We calculated the...

A standardized data structure for describing and exchanging data from remeasured growth and yield plots

Treesearch

Michael D. Sweet; John C. Byrne

1990-01-01

Proposes standard data definitions and format to facilitate the sharing of growth and yield permanent plot data for the development, testing, and improvement of tree or stand growth models. The data structure presented provides standards for documenting sampling design, plot location and summary descriptors, measurement dates, treatments, site attributes, and...

The response of tundra springtails (Collembola, Hexapoda) to human activity on the Murman coast of the Kola Penisula, Russia

NASA Astrophysics Data System (ADS)

Olejniczak, Izabella; Boniecki, Paweł; Kaliszewicz, Anita; Panteleeva, Ninel

2018-03-01

This study was carried out in the Dalne Zelentsy settlement (69°07‧N, 36°03‧E) on the Barents Sea of the Kola Penisula in Russia. Three transects were established: the 'new garden transect'; the 'old garden transect'; and the 'settlement transect'. Overall, the number of springtails increased with distance from the 'settlement' and decreased from the 'old garden' towards the tundra. However, in the case of the 'new garden transect' there were no clear trends in springtail abundance. Eleven species of springtail were found, with Parisotoma notabilis being found at each of the studied areas along the transects. Trends in the species diversity of the springtail communities were not clear, and the values of H‧ ranged from 1.36 to 2.08. The springtail communities located 10 m from the 'new garden' and the 'old garden' were characterized by low species diversity compared with the other sites along the transects (H‧ values of 1.36 and 1.67, respectively). There were no differences in species diversity among the springtail communities along the 'settlement transect'.

PLOT3D user's manual

NASA Technical Reports Server (NTRS)

Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.

1990-01-01

PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.

BENTHIC AMPHIPOD COMMUNITY RESPONSE TO STRESS INDUCED BY ALGAL MATS IN A PACIFIC NORTHWEST ESTUARY

EPA Science Inventory

Amphipod, algal biomass and sediment samples were taken at two- to four-week intervals from June through December, 2000 along lines perpendicular to two transects in Yaquina Bay, OR, extending from within the Zostera marina bed at the river channel edge through intertidal burrowi...

Longleaf Pine Seed Dispersal

Treesearch

William D. Boyer

1963-01-01

Production and dispersal of longleaf pine (Pinus palustris Mill.) seeds were sampled in 1955, 1957, and 1958 on the Escambia Experimental Forest in southwest Alabama.Two transects of seed traps were established at right angles to each of four forest walls enclosing a rectangular 80-acre clearing. Walls were oriented in the cardinal...

Incidense of spider mites in South Texas cotton fields

USDA-ARS?s Scientific Manuscript database

The incidence of spider mites was evaluated· in four locations of south Texas between Progreso (Hidalgo Co.) to Bishop (Nueces Co.). This is an area with a south to north transect of 125 miles from south Progreso to north Bishop (respectively).The other two intermediate sampled locations were Harlin...

Rotational stability test for the diagnosis of radial collateral ligament rupture in the fingers: Anatomical study.

PubMed

Lazarus, P; Hidalgo Diaz, J J; Prunières, G; Pire, E; Taleb, C; Honecker, S; Bellemère, P; Fontaine, C; Liverneaux, P A

2017-04-01

Diagnosing rupture of the radial collateral ligament (RCL) of the finger metacarpophalangeal (MCP) joints is difficult. The aim of this cadaver study was to validate a rotational test for the MCP after RCL transection. With the MCP and proximal interphalangeal joints in flexion, rotation along the axis of the proximal phalanx was applied through an extended distal interphalangeal joint to 36 cadaver fingers. Each finger's pulp described an arc of pronation and supination that was noted on the palm. The test was repeated three times: before transection, after transection of the proper collateral ligament (CL) and after transection of both the proper and accessory CLs. Rotational arcs were measured in pronation and supination. Mean length of the pronation arc after transection of the main RCL was 17.53mm, while it was only 12.41mm before transection for the supination arc. Mean length of the pronation arc after transection of both CLs was 22.83mm compared to only 11.93mm before transection. Our results show a significant difference in pronation stability of the MCP joint after transection of the RCL proper. We can conclude that this rotational stability test is a valid test for diagnosing RCL rupture in MCP joints. Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.

Reptile and amphibian responses to large-scale wildfires in southern California

USGS Publications Warehouse

Rochester, C.J.; Brehme, C.S.; Clark, D.R.; Stokes, D.C.; Hathaway, S.A.; Fisher, R.N.

2010-01-01

In 2003, southern California experienced several large fires that burned thousands of hectares of wildlife habitats and conserved lands. To investigate the effects of these fires on the reptile and amphibian communities, we compared the results from prefire herpetofauna and vegetation sampling to two years of postfire sampling across 38 burned and 17 unburned plots. The sampling plots were spread over four vegetation types and four open space areas within San Diego County. Our capture results indicated that burned chaparral and coastal sage scrub plots lost herpetofaunal species diversity after the fires and displayed a significant shift in overall community structure. Shrub and tree cover at the burned plots, averaged across the second and third postfire years, had decreased by 53 in chaparral and 75 in coastal sage scrub. Additionally, postfire herpetofauna community structure at burned plots was more similar to that found in unburned grasslands. In grassland and woodland/riparian vegetation plots, where shrub and tree cover was not significantly affected by fires, we found no differences in the herpetofaunal species diversity or community composition. At the individual species level, Sceloporus occidentalis was the most abundant reptile in these areas both before and after the fires. We saw increases in the net capture rates for several lizard species, including Aspidoscelis tigris, Phrynosoma coronatum, and Uta stansburiana in burned chaparral plots and Aspidoscelis hyperythra and U. stansburiana in burned coastal sage scrub plots. The toad, Bufo boreas, was detected at significantly fewer burned plots in chaparral after the fires. Additionally, we documented decreases in the number of plots occupied by lizards (Elgaria multicarinata), salamanders (Batrachoseps major), and snakes (Coluber constrictor, Lampropeltis getula, Pituophis catenifer, and Masticophis lateralis) in coastal sage scrub and chaparral after the fires. We discuss the individual species results as they relate to such life-history traits as the susceptibility to initial mortality, the response to the altered postfire habitat, and shifts in the availability of potential prey. We foresee that a continued unnatural fire regime will result in a simplification of the southern California reptile and amphibian communities. ?? 2010 Society for the Study of Amphibians and Reptiles.

Effects of processed oil shale on the element content of Atriplex cancescens

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

Anderson, B.M.

1982-01-01

Samples of four-wing saltbush were collected from the Colorado State University Intensive Oil Shale Revegetation Study Site test plots in the Piceance basin, Colorado. The test plots were constructed to evaluate the effects of processed oil shale geochemistry on plant growth using various thicknesses of soil cover over the processed shale and/or over a gravel barrier between the shale and soil. Generally, the thicker the soil cover, the less the influence of the shale geochemistry on the element concentrations in the plants. Concentrations of 20 elements were larger in the ash of four-wing saltbush growing on the plot with themore » gravel barrier (between the soil and processed shale) when compared to the sample from the control plot. A greater water content in the soil in this plot has been reported, and the interaction between the increased, percolating water and shale may have increased the availability of these elements for plant uptake. Concentrations of boron, copper, fluorine, lithium, molybdenum, selenium, silicon, and zinc were larger in the samples grown over processed shale, compared to those from the control plot, and concentrations for barium, calcium, lanthanum, niobium, phosphorus, and strontium were smaller. Concentrations for arsenic, boron, fluorine, molybdenum, and selenium - considered to be potential toxic contaminants - were similar to results reported in the literature for vegetation from the test plots. The copper-to-molybdenum ratios in three of the four samples of four-wing saltbush growing over the processed shale were below the ratio of 2:1, which is judged detrimental to ruminants, particularly cattle. Boron concentrations averaged 140 ppM, well above the phytotoxicity level for most plant species. Arsenic, fluorine, and selenium concentrations were below toxic levels, and thus should not present any problem for revegetation or forage use at this time.« less

Monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm on permanent plots: sampling methods and statistical properties of data

Treesearch

A.R. Mason; H.G. Paul

1994-01-01

Procedures for monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm are recommended based on many years experience in sampling these species in eastern Oregon and Washington. It is shown that statistically reliable estimates of larval density can be made for a population by sampling host trees in a series of permanent plots in a...

Sources of groundwater based on Helium analyses in and near the freshwater/saline-water transition zone of the San Antonio segment of the Edwards Aquifer, South-Central Texas, 2002-03

USGS Publications Warehouse

Hunt, Andrew G.; Lambert, Rebecca B.; Fahlquist, Lynne

2010-01-01

This report evaluates dissolved noble gas data, specifically helium-3 and helium-4, collected by the U.S. Geological Survey, in cooperation with the San Antonio Water System, during 2002-03. Helium analyses are used to provide insight into the sources of groundwater in the freshwater/saline-water transition zone of the San Antonio segment of the Edwards aquifer. Sixty-nine dissolved gas samples were collected from 19 monitoring wells (categorized as fresh, transitional, or saline on the basis of dissolved solids concentration in samples from the wells or from fluid-profile logging of the boreholes) arranged in five transects, with one exception, across the freshwater/saline-water interface (the 1,000-milligrams-per-liter dissolved solids concentration threshold) of the Edwards aquifer. The concentration of helium-4 (the dominant isotope in atmospheric and terrigenic helium) in samples ranged from 63 microcubic centimeters per kilogram at standard temperature (20 degrees Celsius) and pressure (1 atmosphere) in a well in the East Uvalde transect to 160,587 microcubic centimeters per kilogram at standard temperature and pressure in a well in the Kyle transect. Helium-4 concentrations in the 10 saline wells generally increase from the western transects to the eastern transects. Increasing helium-4 concentrations from southwest to northeast in the transition zone, indicating increasing residence time of groundwater from southwest to northeast, is consistent with the longstanding conceptualization of the Edwards aquifer in which water recharges in the southwest, flows generally northeasterly (including in the transition zone, although more slowly than in the fresh-water zone), and discharges at major springs in the northeast. Excess helium-4 was greater than 1,000 percent for 60 of the 69 samples, indicating that terrigenic helium is largely present and that most of the excess helium-4 comes from sources other than the atmosphere. The helium data of this report cannot be used to identify sources of groundwater in and near the transition zone of the Edwards aquifer in terms of specific geologic (stratigraphic) units or hydrogeologic units (aquifers or confining units). However, the data indicate that the source or sources of the helium, and thus the water in which the helium is dissolved, in the transition zone are mostly terrigenic in origin rather than atmospheric. Whether most helium in and near the transition zone of the Edwards aquifer originated either in rocks outside the transition zone and at depth or in the adjacent Trinity aquifer is uncertain; but most of the helium in the transition zone had to enter the transition zone from the Trinity aquifer because the Trinity aquifer is the hydrogeologic unit immediately beneath and laterally adjacent to the transition zone of the Edwards aquifer. Thus the helium data support a hypothesis of sufficient hydraulic connection between the Trinity and Edwards aquifers to allow movement of water from the Trinity aquifer to the transition zone of the Edwards aquifer.

Assessing the value of multi-receiver low-frequency electromagnetic-induction (EMI) measurement for assessing variation in soil moisture content in field experiments with winter wheat (Triticum aestivum)

NASA Astrophysics Data System (ADS)

Shanahan, Peter; Binley, Andrew; Dodd, Ian; Whalley, Richard; Watts, Chris; Ashton, Rhys; Ober, Eric

2014-05-01

In large plant breeding field trials with multiple genotypes, measuring soil water status (an indicator of crop water uptake) by conventional techniques (e.g. core extraction and penetration resistance) is limited by the cost and effort needed to achieve sufficient replication to apply robust statistical analysis. Geophysical methods may provide a more cost-effective means of more assessing valuable information about soil water status for such studies. We present here results from a field experiment using geophysical techniques for remote mapping of soil water content on sandy loam and silt loam soils in spring/summer 2013 in the UK. The aim of the study was to assess electromagnetic-induction (EMI) conductivity measurements for sensitivity to variations in shallow soil electrical properties and the spatial and temporal mapping of soil water. The CMD Mini-Explorer (GF Instruments) operates with three receiver coils at fixed distances from a transmitter coil (0.32 m, 0.71 m, 1.2 m). Measurement of magnetic field quadrature in horizontal coplanar (HC) and vertical coplanar (VC) of the three receiver coils provides six depths of investigation for the given coil spacing cumulative sensitivities. At the two field sites the instrument was applied to measuring apparent electrical conductivity (ECa) below 7.0 x 1.8 m plots consisting of 23 rain fed winter wheat cultivars and bare soil fallow control plots. These plots were sown in March 2013 and organised into a randomised block design. Electrical resistivity tomography (ERT) surveys along 15 m transects were also conducted at the two sites in order to compare EMI measured ECa. Our results show that progressive soil drying at both sites due to crop uptake significantly decreased (p<0.05) soil ECa. The difference in soil ECa as a result of water uptake between cultivars was found to be significant (p<0.05) from one of the coil configurations (coil spacing 1.8m in HC mode), and only at the silty loam site (no significant difference was found in data from the sandy loam site). The difference in soil ECa over time was expected owing to crop root development and low rainfall during the growing season. It was expected that soil ECa between certain cultivars in the June and July would differ over all investigation depths at both sites. It was not possible in this study to produce calibrations for EMI measured ECa from the ERT data. Our study confirms the suitability of multi-core EMI devices for efficient and repeatable measurements of soil ECa in trials of winter wheat cultivars, providing data on soil ECa with minimal user requirements and instrument error. Differences in soil ECa as a result of crop water uptake was, however, not fully conclusive, since water extraction by the different cultivars is difficult to detect with the instrument, especially on sandy textured soils. The full-depth of investigation (1.8 m) of the instrument used on silt loam soil textures can provide qualitative data on crop performance. Over time, with gradual soil drying, the instrument detected reductions in ECa at all depths of investigation in both sandy and silt textured soils. Further analysis will be done using profiles of electrical conductivity determined from inversions of measured ECa values. ERT data calibration of EMI measured ECa was not possible due to lower than expected variation in ECa measured along the 15 m transect over the field season. This has meant a change in the methodology by having transects crossing soil with greater vertical variation in ECa (determined from field EMI surveys) and surface conditions (e.g. bare and cropped soil).

Halogen Radicals Promote the Photodegradation of Microcystins in Estuarine Systems.

PubMed

Parker, Kimberly M; Reichwaldt, Elke S; Ghadouani, Anas; Mitch, William A

2016-08-16

The transport of microcystin, a hepatotoxin produced by cyanobacteria (e.g., Microcystis aeruginosa), to estuaries can adversely affect estuarine and coastal ecosystems. We evaluated whether halogen radicals (i.e., reactive halogen species (RHS)) could significantly contribute to microcystin photodegradation during transport within estuaries. Experiments in synthetic and natural water samples demonstrated that the presence of seawater halides increased quantum yields for microcystin indirect photodegradation by factors of 3-6. Additional experiments indicated that photoproduced RHS were responsible for this effect. Despite the fact that dissolved organic matter (DOM) concentrations decreased in more saline waters, the calculated photochemical half-life of microcystin decreased 6-fold with increasing salinity along a freshwater-estuarine transect due to the halide-associated increase in quantum yield. Modeling of microcystin photodegradation along this transect indicated that the time scale for RHS-mediated microcystin photodegradation is comparable to the time scale of transport. Microcystin concentrations decline by ∼98% along the transect when considering photodegradation by RHS, but only by ∼54% if this pathway were ignored. These results suggest the importance of considering RHS-mediated photodegradation in future models of microcystin fate in freshwater-estuarine systems.

Multivariate analysis of the geochemistry and mineralogy of soils along two continental-scale transects in North America

USGS Publications Warehouse

Drew, L.J.; Grunsky, E.C.; Sutphin, D.M.; Woodruff, L.G.

2010-01-01

Soils collected in 2004 along two North American continental-scale transects were subjected to geochemical and mineralogical analyses. In previous interpretations of these analyses, data were expressed in weight percent and parts per million, and thus were subject to the effect of the constant-sum phenomenon. In a new approach to the data, this effect was removed by using centered log-ratio transformations to 'open' the mineralogical and geochemical arrays. Multivariate analyses, including principal component and linear discriminant analyses, of the centered log-ratio data reveal the effects of soil-forming processes, including soil parent material, weathering, and soil age, at the continental-scale of the data arrays that were not readily apparent in the more conventionally presented data. Linear discriminant analysis of the data arrays indicates that the majority of the soil samples collected along the transects can be more successfully classified with Level 1 ecological regional-scale classification by the soil geochemistry than soil mineralogy. A primary objective of this study is to discover and describe, in a parsimonious way, geochemical processes that are both independent and inter-dependent and manifested through compositional data including estimates of the elements and corresponding mineralogy. ?? 2010.

Elevational change in woody tissue CO2 efflux in a tropical mountain rain forest in southern Ecuador.

PubMed

Zach, Alexandra; Horna, Viviana; Leuschner, Christoph

2008-01-01

Much uncertainty exists about the magnitude of woody tissue respiration and its environmental control in highly diverse tropical moist forests. In a tropical mountain rain forest in southern Ecuador, we measured the apparent diurnal gas exchange of stems and coarse roots (diameter 1-4 cm) of trees from representative families along an elevational transect with plots at 1050, 1890 and 3050 m a.s.l. Mean air temperatures were 20.8, 17.2 and 10.6 degrees C, respectively. Stem and root CO(2) efflux of 13 to 21 trees per stand from dominant families were investigated with an open gas exchange system while stand microclimate was continuously monitored. Substantial variation in respiratory activity among and within species was found at all sites. Mean daily CO(2) release rates from stems declined 6.6-fold from 1.38 micromol m(-2) s(-1) at 1050 m to 0.21 micromol m(-2) s(-1) at 3050 m. Mean daily CO(2) release from coarse roots decreased from 0.35 to 0.20 micromol m(-2) s(-1) with altitude, but the differences were not significant. There was, thus, a remarkable shift from a high ratio of stem to coarse root respiration rates at the lowest elevation to an apparent equivalence of stem and coarse root CO(2) efflux rates at the highest elevation. We conclude that stem respiration, but not root respiration, greatly decreases with elevation in this transect, coinciding with a substantial decrease in relative stem diameter increment and a large increase in fine and coarse root biomass production with elevation.

Towards Novel Techniques for Root Phenotyping Using GPR

NASA Astrophysics Data System (ADS)

Kobylinski, C.; Neely, H.; Everett, M. E.; Hays, D. B.; Lewis, K.

2017-12-01

The ability to phenotype roots in situ would provide information for carbon sequestration potential through increased root mass, possible water-seeking strategies by plants, and generate data for plant breeders. One technique for root phenotyping is to measure differences in soil moisture and use this data to infer root presence or absence. Current technologies for soil moisture detection include electromagnetic induction and neutron moisture meters; however, ground penetrating radar (GPR) has been suggested to monitor root phenotypes. The objective of this study is to use GPR as a novel technique for detecting roots and classifying root phenotypes based on the detection of differences in dielectric permittivity in response to changes in soil water content. The study will be conducted at two sites in Texas: Thrall, TX (Burleson clay) and Lubbock, TX (Olton clay loam). Three root types will be investigated: fibrous (grain sorghum), tap root (cowpea), and mixed (9-species). Data will be collected along a 10 m linear transect in each plot with a PulseEkko GPR bi-static unit operating at a radio frequency of 500 MHz. Additionally, an EM38-MK2 survey will be performed along each transect. Soil surface moisture readings will be collected with a ML3 ThetaProbe soil moisture sensor and a neutron moisture meter will be used to obtain soil moisture measurements down to 1.2 m. Measurements will be collected every two weeks throughout the growing season. Soil properties including particle size distribution, cation exchange capacity, and bulk density will also be measured. GPR's ability to distinguish root types across soils will be assessed.

Seasonal variability in CDOM absorption and fluorescence properties in the Barataria Basin, Louisiana, USA.

PubMed

Singh, Shatrughan; D'Sa, Eurico; Swenson, Erick

2010-01-01

Absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) along a 124 km transect in the Barataria Basin, a large estuary located in Louisiana, USA, were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from (3.25 +/- 0.56) to (20.76 +/- 2.43) m(-1) for the three month high flow period whereas it varied from (1.48 +/- 1.08) to (25.45 +/- 7.03) m(-1) for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runoff in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak, lowest the T-peak, and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.

Effects of Nitrogen Fertilization and Thinning Treatments on Subsurface Soil Carbon and Nitrogen

NASA Astrophysics Data System (ADS)

Gross, C. D.; James, J. N.; Harrison, R. B.

2016-12-01

Increases in intensively managed forest plantations have caused concern for the long-term productivity and sustainability of these stands, as decreased organic matter retention and shorter rotations can substantially impact soil nutrition both in the short- and long-term. This study aims to provide data for regional responses of soil carbon (C) and nitrogen (N) by depth to fertilization and thinning treatments. Soil was sampled at an intensively managed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation in northwestern Oregon, USA. Nine 0.2-ha plots were sampled with at least three pits per plot. Management regimes included no treatment (control), fertilization (F+), minimal thinning (mT), repeated thinning (rT), and combination treatments (mTF+ and rTF+). Fertilized plots received a total of 1120 kg N ha-1 as urea over 16 years. Bulk density and chemical analysis samples were taken in the middle of succeeding soil layers at depths of 0.1, 0.2, 0.5, 1.0, and 1.5 m. Forest floor samples were collected from a randomly placed quadrat. Preliminary results show an increase in total soil C and N of 113 and 106%, respectively, on the mTF+ plot compared to a control plot. The subsoil, defined here as below 0.2 m, contained over 50% of both soil C and N on the mTF+ plot and experienced greater C and N increases than the surface soil following treatment. This study demonstrates that forest management practices over a relatively short time span (<30 years) can significantly alter subsoil, which comprises a substantial portion of biologically available C and N in terrestrial ecosystems. Subsoil processes are critical to our understanding of changes in soil quality and our ability to accurately assess changes in soil C and N reservoirs.

Macrophyte monitoring along the Trentino side of the Lake Garda

NASA Astrophysics Data System (ADS)

Pellegrini, Giovanna; Monauni, Catia; Fedrizzi, Fabio; Laura, Fravezzi; Paola, Testa; Silvia, Costaraoss; Mario, Mazzurana; Gaetano, Patti; Barbara, Zennaro

2013-04-01

Macrophytes, that grow along the Trentino shorezone of the Lake Garda, were sampled and mapped during summer 2010. The sampling protocol foresees a lake bottom survey until the depth of 15 using GPS system, for identifying sampling sites and transects, waterproof camcorder, batiscope and a rake. The proof of 13/14 meters is the internal limit for macrophyte development. The area between 6 and 13/14 meters was surveyed with a robot camcorder placed on a boat of the fireworks brigade of Trento. This boat was used to track the 14 km of the shorezone of the Trentino part of the Lake Garda. The investigation result is a survey of a wide carex prairie that has no interruption all along the lake perimeter. An inflatable boat was used to inspect the shorezone using a batiscope. The macrophyte samples were collected using a rake. The number of mapped sites is 15, transects are 15 and identified 18 different species. During 2011, in conjunction with the flight MIVIS within the EULAKES project, the macrophyte distribution was confirmed and further inspection was carried out for sampling and classifying caracee. Among the species collected, Chara globularis was present in all sites sampled, while sites 0 and 12, corresponding respectively to local reserve Val Gola and the bay of Torbole, showed the highest biodiversity among sites, with 11 species collected of the 18 total. Within each site, higher number of species were collected between 2 and 5 meters depth's.

Reliability of confidence intervals calculated by bootstrap and classical methods using the FIA 1-ha plot design

Treesearch

H. T. Schreuder; M. S. Williams

2000-01-01

In simulation sampling from forest populations using sample sizes of 20, 40, and 60 plots respectively, confidence intervals based on the bootstrap (accelerated, percentile, and t-distribution based) were calculated and compared with those based on the classical t confidence intervals for mapped populations and subdomains within those populations. A 68.1 ha mapped...

Guidelines for sampling aboveground biomass and carbon in mature central hardwood forests

Treesearch

Martin A. Spetich; Stephen R. Shifley

2017-01-01

As impacts of climate change expand, determining accurate measures of forest biomass and associated carbon storage in forests is critical. We present sampling guidance for 12 combinations of percent error, plot size, and alpha levels by disturbance regime to help determine the optimal size of plots to estimate aboveground biomass and carbon in an old-growth Central...

Effects of Small-Scale Dead Wood Additions on Beetles in Southeastern U.S

Treesearch

Kier D. Klepzig; Michael L. Ferro; Michael D. Ulyshen; Matthew L. Gimmel; Jolie B. Mahfouz; Allan E. Tiarks; Chris E. Carlton

2012-01-01

Pitfall traps were used to sample beetles (Coleoptera) in plots with or without inputs of dead loblolly pine (Pinus taeda L.) wood at four locations (Louisiana, Mississippi, North Carolina and Texas) on the coastal plain of the southeastern United States. The plots were established in 1998 and sampling took place in 1998, 1999, and 2002 (only 1998...

Quality control of measurements made on fixed-area sample plots

Treesearch

Ola Lindgren

2000-01-01

The paper describes results from a large program for quality control of forest measurements. The performance of 87 surveyors was evaluated. Tree heights were usually measured well, whereas the counting of tree-rings on increment cores was a source of considerable bias for many surveyors. During tree count on sample plots, many surveyors had a tendency to forget trees,...

A test of point-sampling in northern hardwoods

Treesearch

Dale S. Solomon

1975-01-01

Plot- and point-sampling were compared with a complete inventory of two different stands of northern hardwoods. Prisms with basal-area factors of 5, 10, 20, 30, and 40 and a ¼-acre plot were used. Only the 5-factor prism gave a significantly different estimate. Therefore, a prism factor of 10 or greater is suggested for use in northern hardwoods.

Edaphic and light conditions of sympatric plant morphotypes in western Amazonia.

PubMed

Roncal, Julissa

2014-01-01

Here I present a dataset of edaphic and light conditions associated with the occurrence of sympatric morphotypes of Geonomamacrostachys (Arecaceae/Palmae), a candidate case study from Amazonia hypothesized to have evolved under ecological speciation. Transects were established in three lowland rainforests in Peru, and the abundance of each local morphotype of this species was recorded in a total area of 4.95 hectares. Composite soil samples and hemispherical photographs were taken along the transects were the species occurred to obtain information on soil nutrients, soil texture, and indirect measurements of light availability. The raw and summary tables disclose the characteristics of each study site and habitats within them, which could be useful to soil scientists, ecologists, and conservationists engaged in similar research activities or meta-analyses in Amazonia.

Vegetation monitoring and classification using NOAA/AVHRR satellite data

NASA Technical Reports Server (NTRS)

Greegor, D. H., Jr.; Norwine, J. R.

1983-01-01

A vegetation gradient model, based on a new surface hydrologic index and NOAA/AVHRR meteorological satellite data, has been analyzed along a 1300 km east-west transect across the state of Texas. The model was developed to test the potential usefulness of such low-resolution data for vegetation stratification and monitoring. Normalized Difference values (ratio of AVHRR bands 1 and 2, considered to be an index of greenness) were determined and evaluated against climatological and vegetation characteristics at 50 sample locations (regular intervals of 0.25 deg longitude) along the transect on five days in 1980. Statistical treatment of the data indicate that a multivariate model incorporating satellite-measured spectral greenness values and a surface hydrologic factor offer promise as a new technique for regional-scale vegetation stratification and monitoring.

[Effects of revegetation approach and terrain on plant species diversity as a result of converting croplands to forests in the Loess region of western Shanxi Province, China].

PubMed

Wu, Wen Juan; Zha, Tong Gang; Zhang, Zhi Qiang

2017-04-18

The plant species diversity of stands converted from croplands as affected by revegetation approaches and terrains was studied using the transect line plot sampling. The goal of the study was to provide reference for evaluation reforestation effects and forest management in the Loess region of western Shanxi Province. The results showed that revegetation approach had a great influence on plant species diversity in stands. The number of species in the natural restoration forest (NF) was 1.6 times of that of Robinia pseudoacacia plantation (RP), the Shannon index of NF was higher, and the Pielou index of NF was lower. Slope position had significant effect on the species diversity, and the three species diversity indices were all in order of bottom of loess gully > middle slope of loess gully > slope of loess hill > top of loess hill. The species diversity indices on the shady slope were higher than those on the sunny slope, while the difference was not significant. Integrated effects of terrain and revegetation approach had significant influences on species diversity. The species diversity was highest at the bottom of shady slope of NF, and the species evenness was highest at the bottom of shady slope of RP. For improving the species diversity, the afforestation design in the Loess area must consider terrain position and the natural forest recovery process following the principle of 'selecting suitable tree species for the right site'.

Q-mode versus R-mode principal component analysis for linear discriminant analysis (LDA)

NASA Astrophysics Data System (ADS)

Lee, Loong Chuen; Liong, Choong-Yeun; Jemain, Abdul Aziz

2017-05-01

Many literature apply Principal Component Analysis (PCA) as either preliminary visualization or variable con-struction methods or both. Focus of PCA can be on the samples (R-mode PCA) or variables (Q-mode PCA). Traditionally, R-mode PCA has been the usual approach to reduce high-dimensionality data before the application of Linear Discriminant Analysis (LDA), to solve classification problems. Output from PCA composed of two new matrices known as loadings and scores matrices. Each matrix can then be used to produce a plot, i.e. loadings plot aids identification of important variables whereas scores plot presents spatial distribution of samples on new axes that are also known as Principal Components (PCs). Fundamentally, the scores matrix always be the input variables for building classification model. A recent paper uses Q-mode PCA but the focus of analysis was not on the variables but instead on the samples. As a result, the authors have exchanged the use of both loadings and scores plots in which clustering of samples was studied using loadings plot whereas scores plot has been used to identify important manifest variables. Therefore, the aim of this study is to statistically validate the proposed practice. Evaluation is based on performance of external error obtained from LDA models according to number of PCs. On top of that, bootstrapping was also conducted to evaluate the external error of each of the LDA models. Results show that LDA models produced by PCs from R-mode PCA give logical performance and the matched external error are also unbiased whereas the ones produced with Q-mode PCA show the opposites. With that, we concluded that PCs produced from Q-mode is not statistically stable and thus should not be applied to problems of classifying samples, but variables. We hope this paper will provide some insights on the disputable issues.

Effect of proximity to a cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens and evaluation of the potential for airborne transmission.

PubMed

Berry, Elaine D; Wells, James E; Bono, James L; Woodbury, Bryan L; Kalchayanand, Norasak; Norman, Keri N; Suslow, Trevor V; López-Velasco, Gabriela; Millner, Patricia D

2015-02-01

The impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance). Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased. Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur. Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust. Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

A statistically valid method for using FIA plots to guide spectral class rejection in producing stratification maps

Treesearch

Michael L. Hoppus; Andrew J. Lister

2002-01-01

A Landsat TM classification method (iterative guided spectral class rejection) produced a forest cover map of southern West Virginia that provided the stratification layer for producing estimates of timberland area from Forest Service FIA ground plots using a stratified sampling technique. These same high quality and expensive FIA ground plots provided ground reference...

Sampling design for long-term regional trends in marine rocky intertidal communities

USGS Publications Warehouse

Irvine, Gail V.; Shelley, Alice

2013-01-01

Probability-based designs reduce bias and allow inference of results to the pool of sites from which they were chosen. We developed and tested probability-based designs for monitoring marine rocky intertidal assemblages at Glacier Bay National Park and Preserve (GLBA), Alaska. A multilevel design was used that varied in scale and inference. The levels included aerial surveys, extensive sampling of 25 sites, and more intensive sampling of 6 sites. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope ≤30° was rare. This unexpected finding illustrated one value of probability-based surveys and led to a shift in the target habitat type to include steeper, more mixed rocky habitat. Subsequently, we evaluated the statistical power of different sampling methods and sampling strategies to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles Balanomorpha, the mussel Mytilus trossulus, and the rockweed Fucus distichus subsp. evanescens. There was greatest power to detect trends in Mytilus and lesser power for barnacles and Fucus. Because of its greater power, the extensive, coarse-grained sampling scheme was adopted in subsequent years over the intensive, fine-grained scheme. The sampling attributes that had the largest effects on power included sampling of “vertical” line transects (vs. horizontal line transects or quadrats) and increasing the number of sites. We also evaluated the power of several management-set parameters. Given equal sampling effort, sampling more sites fewer times had greater power. The information gained through intertidal monitoring is likely to be useful in assessing changes due to climate, including ocean acidification; invasive species; trampling effects; and oil spills.

Barrier effects of remote high mountain on atmospheric metal transport in the eastern Tibetan Plateau.

PubMed

Bing, Haijian; Zhou, Jun; Wu, Yanhong; Luo, Xiaosan; Xiang, Zhongxiang; Sun, Hongyang; Wang, Jipeng; Zhu, He

2018-07-01

Anthropogenic metals adsorbed on suspended fine particles can be deposited on remote and inaccessible high mountains by long-range atmospheric transport. In this study, we investigated the cadmium (Cd) and lead (Pb) in the soils, mosses and rainfall of three transects on the Gongga Mountain, eastern Tibetan Plateau, to understand the mountain interception effects on their atmospheric transport. The concentrations of Cd and Pb in the soils and mosses displayed a pattern of eastern transect>northern transect>western transect. The distribution of Cd and Pb on the eastern transect increased from 2000 to 2900m a.s.l. (above sea level), decreased toward the timberline, and increased again with altitude; on the northern transect, it generally decreased with altitude whereas a distribution trend was not clearly observed on the western transect. The Cd and Pb concentrations in the rainfall of the eastern transect generally decreased with altitude, and they were higher inside forests than outside forests and temporally higher in the winter than the summer. The Pb isotopic ratios coupled with moss bio-monitoring distinguished anthropogenic sources of Cd and Pb on the eastern and northern transects, whereas bedrock weathering was the main source of Cd and Pb on the western transect. We proposed a conceptual model to delineate the effects of terrain, local climate and vegetation on the transport of atmospheric metals. Our results highlighted the high mountains in the eastern Tibetan Plateau as an effective natural barrier limiting atmospheric metal transport. Copyright © 2018 Elsevier B.V. All rights reserved.

Unmanned Aerial Survey of Elephants

PubMed Central

Vermeulen, Cédric; Lejeune, Philippe; Lisein, Jonathan; Sawadogo, Prosper; Bouché, Philippe

2013-01-01

The use of a UAS (Unmanned Aircraft System) was tested to survey large mammals in the Nazinga Game Ranch in the south of Burkina Faso. The Gatewing ×100™ equipped with a Ricoh GR III camera was used to test animal reaction as the UAS passed, and visibility on the images. No reaction was recorded as the UAS passed at a height of 100 m. Observations, made on a set of more than 7000 images, revealed that only elephants (Loxodonta africana) were easily visible while medium and small sized mammals were not. The easy observation of elephants allows experts to enumerate them on images acquired at a height of 100 m. We, therefore, implemented an aerial strip sample count along transects used for the annual wildlife foot count. A total of 34 elephants were recorded on 4 transects, each overflown twice. The elephant density was estimated at 2.47 elephants/km2 with a coefficient of variation (CV%) of 36.10%. The main drawback of our UAS was its low autonomy (45 min). Increased endurance of small UAS is required to replace manned aircraft survey of large areas (about 1000 km of transect per day vs 40 km for our UAS). The monitoring strategy should be adapted according to the sampling plan. Also, the UAS is as expensive as a second-hand light aircraft. However the logistic and flight implementation are easier, the running costs are lower and its use is safer. Technological evolution will make civil UAS more efficient, allowing them to compete with light aircraft for aerial wildlife surveys. PMID:23405088

Comparison of line transects and point counts for monitoring spring migration in forested wetlands

USGS Publications Warehouse

Wilson, R.R.; Twedt, D.J.; Elliott, A.B.

2000-01-01

We compared the efficacy of 400-m line transects and sets of three point counts at detecting avian richness and abundance in bottomland hardwood forests and intensively managed cottonwood (Populus deltoides) plantations within the Mississippi Alluvial Valley. We detected more species and more individuals on line transects than on three point counts during 218 paired surveys conducted between 24 March and 3 June, 1996 and 1997. Line transects also yielded more birds per unit of time, even though point counts yielded higher estimates of relative bird density. In structurally more-complex bottomland hardwood forests, we detected more species and individuals on line transects, but in more-open cottonwood plantations, transects surpassed point counts only at detecting species within 50 m of the observer. Species richness and total abundance of Nearctic-Neotropical migrants and temperate migrants were greater on line transects within bottomland hardwood forests. Within cottonwood plantations, however, only species richness of Nearctic-Neotropical migrants and total abundance of temperate migrants were greater on line transects. Because we compared survey techniques using the same observer, within the same forest stand on a given day, we assumed that the technique yielding greater estimates of avian species richness and total abundance per unit of effort is superior. Thus, for monitoring migration within hardwood forests of the Mississippi Alluvial Valley, we recommend using line transects instead of point counts.

Sample size and the detection of a hump-shaped relationship between biomass and species richness in Mediterranean wetlands

USGS Publications Warehouse

Espinar, J.L.

2006-01-01

Questions: What is the observed relationship between biomass and species richness across both spatial and temporal scales in communities of submerged annual macrophytes? Does the number of plots sampled affect detection of hump-shaped pattern? Location: Don??ana National Park, southwestern Spain. Methods: A total of 102 plots were sampled during four hydrological cycles. In each hydrological cycle, the plots were distributed randomly along an environmental flooding gradient in three contrasted microhabitats located in the transition zone just below the upper marsh. In each plot (0.5 m x 0.5 m), plant density and above- and below-ground biomass of submerged vegetation were measured. The hump-shaped model was tested by using a generalized linear model (GLM). A bootstrap procedure was used to test the effect of the number of plots on the ability to detect hump-shaped patterns. Result: The area exhibited low species density with a range of 1 - 9 species and low values of biomass with a range of 0.2 - 87.6 g-DW / 0.25 m2. When data from all years and all microhabitats were combined, the relationships between biomass and species richness showed a hump-shaped pattern. The number of plots was large enough to allow detection of the hump-shaped pattern across microhabitats but it was too small to confirm the hump-shaped pattern within each individual microhabitat. Conclusion: This study provides evidence of hump-shaped patterns across microhabitats when GLM analysis is used. In communities of submerged annual macrophytes in Mediterranean wetlands, the highest species density occurs in intermediate values of biomass. The bootstrap procedure indicates that the number of plots affects the detection of hump-shaped patterns. ?? IAVS; Opulus Press.

Polar plot representation of time-resolved fluorescence.

PubMed

Eichorst, John Paul; Wen Teng, Kai; Clegg, Robert M

2014-01-01

Measuring changes in a molecule's fluorescence emission is a common technique to study complex biological systems such as cells and tissues. Although the steady-state fluorescence intensity is frequently used, measuring the average amount of time that a molecule spends in the excited state (the fluorescence lifetime) reveals more detailed information about its local environment. The lifetime is measured in the time domain by detecting directly the decay of fluorescence following excitation by short pulse of light. The lifetime can also be measured in the frequency domain by recording the phase and amplitude of oscillation in the emitted fluorescence of the sample in response to repetitively modulated excitation light. In either the time or frequency domain, the analysis of data to extract lifetimes can be computationally intensive. For example, a variety of iterative fitting algorithms already exist to determine lifetimes from samples that contain multiple fluorescing species. However, recently a method of analysis referred to as the polar plot (or phasor plot) is a graphical tool that projects the time-dependent features of the sample's fluorescence in either the time or frequency domain into the Cartesian plane to characterize the sample's lifetime. The coordinate transformations of the polar plot require only the raw data, and hence, there are no uncertainties from extensive corrections or time-consuming fitting in this analysis. In this chapter, the history and mathematical background of the polar plot will be presented along with examples that highlight how it can be used in both cuvette-based and imaging applications.

Albedo of bare ice near the Trans-Antarctic Mountains to represent sea-glaciers on the tropical ocean of Snowball Earth

NASA Astrophysics Data System (ADS)

Warren, S. G.; Dadic, R.; Mullen, P.; Schneebeli, M.; Brandt, R. E.

2012-12-01

The albedos of snow and ice surfaces are, because of their positive feedback, crucial to the initiation, maintenance, and termination of a snowball event, as well as for determining the ice thickness on the ocean. Despite the name, Snowball Earth would not have been entirely snow-covered. As on modern Earth, evaporation would exceed precipitation over much of the tropical ocean. After a transient period with sea ice, the dominant ice type would probably be sea-glaciers flowing in from higher latitude. As they flowed equatorward into the tropical region of net sublimation, their surface snow and subsurface firn would sublimate away, exposing bare glacier ice to the atmosphere and to solar radiation. This ice would be freshwater (meteoric) ice, which originated from snow and firn, so it would contain numerous air bubbles, which determine the albedo. The modern surrogate for this type of ice (glacier ice exposed by sublimation, which has never experienced melting), are the bare-ice surfaces of the Antarctic Ice Sheet near the Trans-Antarctic Mountains. These areas have been well mapped because of their importance in the search for meteorites. A transect across an icefield can sample ice of different ages that has traveled to different depths en route to the sublimation front. On a 6-km transect from snow to ice near the Allan Hills, spectral albedo was measured and 1-m core samples were collected. This short transect is meant to represent a north-south transect across many degrees of latitude on the snowball ocean. Surfaces on the transect transitioned through the sequence: new snow - old snow - firn - young white ice - old blue ice. The transect from snow to ice showed a systematic progression of decreasing albedo at all wavelengths, as well as decreasing specific surface area (SSA; ratio of air-ice interface area to ice mass) and increasing density. The measured spectral albedos are integrated over wavelength and weighted by the spectral solar flux to obtain broadband albedos. These range from 0.8 for snow to 0.55-0.6 for blue ice, which is in the range that favors thick ice over the tropical ocean of Snowball Earth. Air bubbles in the ice, as well as cracks, are responsible for the reflection of sunlight; their contributions to SSA were determined by micro-computed tomography. Scattering by bubbles dominates; removing cracks from the radiative-transfer calculation causes only a slight reduction of albedo. Although what determines the albedo is the SSA of bubbles or snow grains, the broadband albedo also shows a systematic relation to the snow or ice density, suggesting that density might serve as a surrogate variable that will be easier to predict than SSA in an ice-sheet model, using a parameterization for firn densification.

Biological and physical factors controlling aggregate stability under different climatic conditions in Southern Spain.

NASA Astrophysics Data System (ADS)

Ángel Gabarrón-Galeote, Miguel; Damián Ruiz-Sinoga, Jose; Francisco Martinez-Murillo, Juan; Lavee, Hanoch

2013-04-01

Soil aggregation is a key factor determining the soil structure. The presence of stable aggregates is essential to maintain a good soil structure, that in turn plays an important role in sustaining agricultural productivity and preserving environmental quality. A wide range of physical and biological soil components are involved in the aggregate formation and stabilization, namely clay mineral content; the quantity and quality of organic matter, that can be derived from plants, fungal hyphae, microorganism and soil animals; and the soil water content. Climatic conditions, through their effect on soil water content, vegetation cover and organic matter content, are supposed to affect soil aggregation. Thus the main objective of this research is to analyse the effect of organic matter, clay content and soil water content on aggregate stability along a climatic transect in Southern Spain. This study was conducted in four catchments along a pluviometric gradient in the South of Spain (rainfall depth decreases from west to east from more than 1000 mm year-1 to less than 300 mm year-1) and was based on a methodology approximating the climatic gradient in Mediterranean conditions. The selected sites shared similar conditions of geology, topography and soil use, which allowed making comparisons among them and relating the differences to the pluviometric conditions. In February 2007, 250 disturbed and undisturbed samples from the first 5cm of the soil were collected along the transect. We measured the aggregate stability, organic matter, clay content and bulk density of every sample. In the field we measured rainfall, air temperature, relative humidity, wind speed, wind direction, solar radiation, potential evapotranspiration, soil water content, vegetation cover and presence of litter. Our results suggest that aggregate stability is a property determined by a great number of highly variable factors, which can make extremely difficult to predict its behavior taking in account only a few of them. The climate exerted a great influence in aggregate stability and could determine by itself the soil structure along the climate transect. As a result, properties unrelated in a specific point of the climate transect became highly associated if we took it into account completely. Along the climate transect analyzed could be defined two areas, separated by a threshold located between 573.6 mm y-1 and 335.9 mm y-1. In the wettest part soil structure was mainly determined by biotic factors and in the driest part was highly probable that abiotic factors play a key role determining aggregate stability.

Multi-element study of sediments from the river Khai River - Nha Trang Bay estuarine system, South China Sea.

NASA Astrophysics Data System (ADS)

Koukina, Sofia; Lobus, Nikolai; Peresypkin, Valery; Baturin, Gleb; Smurov, Andrey

2013-04-01

Major (Al, Fe, Ti, Mg, Ca, Na, K), minor (Mn) and trace (Cr, Ni, Cd, V, Zn, Cu, Pb, Sb, Bi, Sn, Ag, Li, Co, As, Zr, Mo, Hg) elements along with nutrients (TOC, TS, TP) and TIC were first determined in ten surface sediment samples from the Khai River - Nha Trang Bay estuarine system, South China Sea. According to the sediment quality guidelines and reference background values, most of the element contents that were studied were below the threshold levels, while the content of Ag exceeded significantly the hazardous levels in the most of the samples along the river - sea transect. The local anthropogenic and/or environmental sources of Ag within the region need special study. Aluminum and lithium normalization indicated some specific features in the abundance and distribution of the elements along the salinity gradient. The mean grain size of the sediments decreased from the river part to the bay part of the transect. Sedimentary TOC was relatively low (1-2 %) and showed independent distribution along the river - sea transect in relation to the other elements that were studied. Ca, Ba and Sr distribution showed some sporadic enrichment and were largely controlled by the TIC content in sediments. Sedimentary TP, Al, Fe, Mn, Ti, Na, K, Li, Co, Cs, Zn and V varied within the narrow range and tended to increase seaward. These elements are most likely controlled by the accumulation of their fine grained aluminosilicate host minerals and materials at sites determined by hydrodynamic conditions, i. e., in the sea floor depression. TS, As, Sn, Bi, U, Cd and Mo were relatively low in the sediments studied and tended to decrease seaward with the slight elevation in the intermediate part of the transect. These elements can be scavenged by and/or co-precipitated with the dissolved and particulate materials of the river discharge and further deposited on the river - sea geochemical barrier in the course of estuarine sedimentation. The distribution of Ni, Cr, Zr Cu, Pb, Sb, Hg and, especially, Ag was characterized by anomalous high concentrations in the intermediate part of the river - sea transect at sites located in the harbor zone. This might be due to the point anthropogenic pollution from local human activities, i.e., fishing, shipping, fueling, waste and sewage sludge outflow, and, especially, from the construction of new touristic facilities in the Nha Trang Bay. Overall, the abundance and distribution of the environmental/anthropogenic elements are controlled by various estuarine biogeochemical processes characteristic for the marginal filter of the estuarine water mixing zone.

Comparison between surgical and standing percutaneous contact Nd:YAG laser periosteal transection for potential treatment of equine limb deformities

NASA Astrophysics Data System (ADS)

Tate, Lloyd P.; Baines, Steven J.; Meuten, Donald J.; Stefanacci, J.

1994-09-01

Medial and lateral aspects of both radiuses were subjected to periosteal transection of nine healthy equine foals. One site per foal was subjected to surgical periosteal transection and elevation under general anesthesia. The remaining three sites of each foal after injection of a local anesthetic received Nd:YAG contact percutaneous periosteal transection. All radiuses were evaluated radiographically prior to periosteal transection and immediately prior to euthanasia. Foals were euthanized at 3 days, 31 to 34 days, and 67 days post-periosteal transection and gross postmortem and histologic examination performed on each site. Radiographically, periosteal proliferation occurred at all the conventional surgery sites and a majority of the percutaneous laser sites by 30 days post-treatment and was present at 67 days. No limb angulations were noted to occur in any of the foals. The conclusion of the study was that Nd:YAG percutaneous laser periosteal transection was successful in producing periosteal obliteration but with a different histologic appearance than that produced by conventional surgery.

Non-transecting bulbar urethroplasty

PubMed Central

Andrich, Daniela E.; Mundy, Anthony R.

2015-01-01

Excision and end-to-end anastomosis (EPA) has been the preferred urethroplasty technique for short bulbar strictures and is associated with an excellent functional outcome. Driven by concerns over the potential morbidity associated with dividing the urethra, therefore compromising spongiosal blood flow, as well as spongiofibrosis being superficial in the majority of non-traumatic bulbar strictures, the non-transecting technique for bulbar urethroplasty has been developed with the aim of achieving the same success as EPA without the morbidity associated with transection. This manuscript highlights the fundamental principles underlying the ongoing debate—transection or non-transection of the strictured bulbar urethra? The potential advantages of avoiding dividing the corpus spongiosum of the urethra are discussed. The non-transecting anastomotic procedure together with its various modifications are decribed in detail. Our experience with this technique is presented. Non-transecting excision of spongiofibrosis with preservation of well vascularised underlying spongiosum provides an excellent alternative to dividing the urethra during urethroplasty for short non-traumatic proximal bulbar strictures. PMID:26816808

Vegetation dynamics during the late Pleistocene in the Barreirinhas region, Maranhão State, northeastern Brazil, based on carbon isotopes in soil organic matter

NASA Astrophysics Data System (ADS)

Pessenda, Luiz Carlos Ruiz; Ribeiro, Adauto de Souza; Gouveia, Susy Eli Marques; Aravena, Ramon; Boulet, Rene; Bendassolli, José Albertino

2004-09-01

The study place is in the Barreirinhas region, Maranhão State, northeastern Brazil. A vegetation transect of 78 km was studied among four vegetation types: Restinga (coastal vegetation), Cerrado (woody savanna), Cerradão (dense woody savanna), and Forest, as well as three forested sites around Lagoa do Caçó, located approximately 10 km of the transect. Soil profiles in this transect were sampled for δ13C analysis, as well as buried charcoal fragments were used for 14C dating. The data interpretation indicated that approximately between 15,000 and ˜9000 14C yr B.P., arboreal vegetation prevailed in the whole transect, probably due to the presence of a humid climate. Approximately between ˜9000 and 4000-3000 14C yr B.P., there was the expansion of the savanna, probably related to the presence of drier climate. From ˜4000-3000 14C yr B.P. to the present, the results indicated an increase in the arboreal density in the area, due to the return to a more humid and probably similar climate to the present. The presence of buried charcoal fragments in several soil depths suggested the occurrence of palaeofires during the Holocene. The vegetation dynamic inferred in this study for northeastern Brazil is in agreement with the results obtained in areas of Amazon region, based on pollen analysis of lake sediments and carbon isotope analysis of soil organic matter (SOM), implying than similar climatic conditions have affected these areas during the late Pleistocene until the present.