Effects of stocking density of the white shrimp Litopenaeus vannamei (Boone) on immunities, antioxidant status, and resistance against Vibrio harveyi in a biofloc system.

PubMed

Liu, Gang; Zhu, Songming; Liu, Dezhao; Guo, Xishan; Ye, Zhangying

2017-08-01

Determining optimum stocking density of the white shrimp Litopenaeus vannamei (Boone) is a big concern for shrimp farmers. However, few studies have assessed the influence of stocking density on the antioxidant status, immunology, digestive enzyme activities, and growth performance of white shrimp in biofloc systems. In this study, these parameters of white shrimp in a biofloc system were compared at three stocking densities: 300 orgs m -3 as low stocking density (LD), 400 orgs m -3 as medium stocking density (MD), and 500 orgs m -3 as high stocking density (HD). The feed conversion ratio in the LD group was significantly lower than that in the MD and HD groups (P < 0.05), and the ultimate individual weight in the LD group was significantly higher than that in the other two groups (P < 0.05). The antioxidant status and immunology parameters, including complement 3, complement 4, lysozyme, superoxide dismutase, glutathione peroxidase and malondialdehyde were all depressed in the HD groups. Furthermore, activities of the digestive enzymes, amylase, trypsin, and lipase were lower in the MD and HD groups than that in the LD group. The highest relative percentage survival was observed in the LD group 10 days after challenge with the pathogen Vibrio harveyi. Results of this study indicated that the immune status and welfare of white shrimp can be seriously impaired in the HD condition (i.e., ≥500 m -3 ) in biofloc systems. These findings can be used to determine suitable stocking densities in the white shrimp farming industry using the biofloc system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Controls on the spatial variability of key soil properties: comparing field data with a mechanistic soilscape evolution model

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Giraldez, J. V.

2016-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of a geostatistical versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

A look at dairy mob grazing in the Northeast

USDA-ARS?s Scientific Manuscript database

Proponents of ultra-high stocking density (UHSD) grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 kg/ha of beef cattle on small paddocks with rest periods up to 125 days. However, it is unclear if this management te...

Effect of stocking density on water quality and (Growth, Body Composition and Plasma Cortisol Content) performance of pen-reared rainbow trout ( Oncorhynchus mykiss)

NASA Astrophysics Data System (ADS)

Liu, Qun; Hou, Zhishuai; Wen, Haishen; Li, Jifang; He, Feng; Wang, Jinhuan; Guan, Biao; Wang, Qinglong

2016-08-01

The goal of the study was to examine the effect of stocking density on the water quality of culture area, as well as the growth, body composition and cortisol content of rainbow trout ( Oncorhynchus mykiss). Pen-reared trout were stocked in densities of 40, 60, 80 fish individuals m-3 (4.6, 6.6, 8.6 kg m-3, SD1, SD2 and SD3 groups, respectively) for 300 days. Compared to the water from SD1 and SD2, that from SD3 exhibited significantly higher NH 4 + -N content and COD (chemical-oxygen-demand), and a significant reduction of dissolved oxygen in day 180 (40.6 kg m-3). Stocking density was significantly associated with body weight, standard length, VSI (viscerosomatic index), CF (condition factor) and FC (food coefficient) in group SD3, particularly in day 240 and day 300 (45 or 49.3 kg m-3). Increased crude fat and decreased crude protein were displayed in high density group when the density reached to 36 kg m-3. As a cumulative effect of density-related stress, VSI, CF, FC, moisture, and crude protein content varied over time in each density group (SD1, SD2, and SD3). In summary, trout exhibited a better growth performance in low density (26.3 kg m-3) than those reared in high densities (36 and 45 kg m-3). The results indicate that rainbow trout (114.44 g ± 6.21 g, 19.69 cm ± 0.31 cm) initially stocked in 6.6 or 8.6 kg m-3 should be lightened to less than 36 kg m-3 after an intensive rearing for 240 days.

A wave function for stock market returns

NASA Astrophysics Data System (ADS)

Ataullah, Ali; Davidson, Ian; Tippett, Mark

2009-02-01

The instantaneous return on the Financial Times-Stock Exchange (FTSE) All Share Index is viewed as a frictionless particle moving in a one-dimensional square well but where there is a non-trivial probability of the particle tunneling into the well’s retaining walls. Our analysis demonstrates how the complementarity principle from quantum mechanics applies to stock market prices and of how the wave function presented by it leads to a probability density which exhibits strong compatibility with returns earned on the FTSE All Share Index. In particular, our analysis shows that the probability density for stock market returns is highly leptokurtic with slight (though not significant) negative skewness. Moreover, the moments of the probability density determined under the complementarity principle employed here are all convergent - in contrast to many of the probability density functions on which the received theory of finance is based.

Response to dietary supplementation of L-glutamine and L-glutamate in broiler chickens reared at different stocking densities under hot, humid tropical conditions.

PubMed

Shakeri, M; Zulkifli, I; Soleimani, A F; O'Reilly, E L; Eckersall, P D; Anna, A A; Kumari, S; Abdullah, F F J

2014-11-01

A study was conducted to determine whether supplementing AminoGut (a commercial dietary supplement containing a mixture of l-glutamine and l-glutamic acid) to broiler chickens stocked at 2 different densities affected performance, physiological stress responses, foot pad dermatitis incidence, and intestinal morphology and microflora. A randomized design in a factorial arrangement with 4 diets [basal diet, basal diet + 0.5% AminoGut from d 1 to 21, basal diet + 0.5% AminoGut from d 1 to 42, and basal diet + virginiamycin (0.02%) for d 1 to 42] and 2 stocking densities [0.100 m(2)/bird (23 birds/pen; LD) or 0.067 m(2)/bird (35 birds/pen; HD)]. Results showed that villi length and crypt depth were not changed by different dietary treatments. However, birds in the HD group had smaller villi (P = 0.03) compared with those of the LD group. Regardless of diet, HD consistently increased the serum concentrations of ceruloplasmin, α-1 acid glycoprotein, ovotransferin, and corticosterone (P = 0.0007), and elevated heterophil to lymphocyte ratio (0.0005). Neither AminoGut supplementation nor stocking density affected cecal microflora counts. In conclusion, under the conditions of this study, dietary supplementation of AminoGut, irrespective of stocking density, had no beneficial effect on growth performance, intestinal morphology, and physiological adaptive responses of broiler chickens raised under hot and humid tropical conditions. However, AminoGut supplementation from d 1 to 42 was beneficial in reducing mortality rate. Also, the increased serum concentrations of a wide range of acute phase proteins together with elevated corticosterone and heterophil to lymphocyte ratio suggested that high stocking density induced an acute phase response either indirectly as a result of increased incidence of inflammatory diseases such as foot pad dermatitis or possibly as a direct physiological response to the stress of high stocking density. ©2014 Poultry Science Association Inc.

Results after 20 years from a western larch levels-of-growing-stock study.

Treesearch

K.W. Seidel

1987-01-01

The 20-year growth response from a levels-of-growing-stock study in an even-aged western larch stand in eastern Oregon, first thinned at age 33, showed that trees growing at low stand densities grew more rapidly in diameter than trees in high-density plots. Height growth was relatively uniform among density levels. Both basal-area and total cubic-volume increment...

Effects of stocking density on lipid deposition and expression of lipid-related genes in Amur sturgeon (Acipenser schrenckii).

PubMed

Ren, Yuanyuan; Wen, Haishen; Li, Yun; Li, Jifang; He, Feng; Ni, Meng

2017-12-01

To investigate the correlation between lipid deposition variation and stocking density in Amur sturgeon (Acipenser schrenckii) and the possible physiological mechanism, fish were conducted in different stocking densities (LSD 5.5 kg/m 3 , MSD 8.0 kg/m 3 , and HSD 11.0 kg/m 3 ) for 70 days and then the growth index, lipid content, lipase activities, and the mRNA expressions of lipid-related genes were examined. Results showed that fish subjected to higher stocking density presented lower final body weights (FBW), specific growth ratio (SGR), and gonad adipose tissue index (GAI) (P < 0.05). Lower lipid content was observed in the liver, gonad adipose tissue and muscle in sturgeons held in HSD group (P < 0.05). The serum concentrations of triglyceride (TG), total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) decreased significantly with increasing stocking density, while no significant change was observed for low-density lipoprotein cholesterol (LDL-C). Furthermore, the cDNAs encoding lipoprotein lipase (LPL) and hepatic lipase (HL) were isolated in Amur sturgeon, respectively. The full-length LPL cDNA was composed of 1757 bp with an open reading frame of 501 amino acids, while the complete nucleotide sequences of HL covered 1747 bp encoding 499 amino acids. In the liver, the activities and mRNA levels of LPL were markedly lower in HSD group, which were consistent with the variation tendency of HL. Fish reared in HSD group also presented lower levels of activities and mRNA expression of LPL in the muscle and gonad. Moreover, the expressions of peroxisome proliferator-activated receptor α (PPARα) in both the liver and skeletal muscle were significantly upregulated in HSD group. Overall, the results indicated that high stocking density negatively affects growth performance and lipid deposition of Amur sturgeon to a certain extent. The downregulation of LPL and HL and the upregulation of PPARα may be responsible for the lower lipid distribution of Amur sturgeon in higher stocking density.

High density culture of white bass X striped bass fingerlings in raceways using power plant heated effluent

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

Collins, C.M.; Burton, G.L.; Schweinforth, R.L.

1983-06-01

White bass (Morone chrysops) X striped bass (M. saxatilis) hybrids weighing 1691/lb were initially stocked in five 24 ft/sup 3/ floating screen cages for 20 days. Hybrids averaging one inch in total length and 361 fish/lb were released in four 614 ft/sup 3/ concrete raceways. Two stocking densities, 2.6 and 5.1 fish/ft/sup 3/, were evaluated in the 94-day study using a flow rate of 300 gpm/raceway. Water temperatures averaged 79/sup 0/F and water quality was adequate throughout the production period. Fish were hand fed to satiation daily. Columnaris and Aeromonas hydrophila caused the most serious disease problems. Gas supersaturation wasmore » suspect in high mortality levels during cage culture of hybrid bass fry. Cannibalism may have been responsible for unaccountable losses prior to raceway stocking and at harvest. The study yielded 5773 hybrids weighing 658 lb. The high density treatment showed greater weight gain, average weight, average length and percent survival as well as improved food conversion. Results suggest that higher stocking densities and periodic grading may increase production and suppress cannibalism. 10 references, 3 figures, 3 tables.« less

Dairy farmers using mob grazing in Pennsylvania and New York

USDA-ARS?s Scientific Manuscript database

Proponents of ultra-high stocking density grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 500,000 lb per acre of beef cattle on small paddocks with rest periods up to 180 days. However, it is unclear if this management tec...

Influence of light-dark schedules and stocking density on behaviour, risk of leg problems and occurrence of chronic fear in broilers.

PubMed

Sanotra, G S; Lund, J Damkjer; Vestergaard, K S

2002-07-01

1. The aims of this study were to determine (1) the effect of light-dark schedules on the walking ability, the risk of tibial dyschondroplasia (TD) as well as the duration of tonic immobility (TI) reactions in commercial broiler flocks and (2) the effect of a daily dark period and reduced density on the behaviour of broiler chickens. 2. Experiment 1. Group 1 had a 2 to 8 h daily dark period from 2 to 26 d of age (light-dark programme A) at a stocking density of 28.4 chicks/m2. Group 2 had 8 h of darkness daily from 2 to 38 d of age (light-dark programme B) at 24 chicks/m2. The control group had 24 h continuous light at 28.4 chicks/m2. 3. Experiment 2. Behaviour was studied with and without a daily 8 h dark period and at high (30 chicks/m2) and low (18 chicks/m2) stocking densities. 4. Programme B reduced the prevalence of impaired walking ability, corresponding to gait score > 2, when compared with controls. The effect on walking ability corresponding to gait score > 0 approached significance. 5. Both light-dark programmes reduced the occurrence of TD. Programme B (combined with reduced stocking density), however, had the greater effect. 6. Both light-dark programmes reduced the duration of TI, compared with controls (mean = 426 s) Programme B resulted in a larger reduction (alpha = -156.9 s) than programme A (alpha = -117.0). 7. The proportions of chicks drinking, eating, pecking, scratching, standing and performing vertical wing-shakes increased--both when the 8 h dark period and the reduced stocking density were applied separately and in combination (experiment 2). 8. For all behaviours, except standing, the effect of the dark period was largest in broilers kept at the high stocking density (d 40).

Can Process Understanding Help Elucidate The Structure Of The Critical Zone? Comparing Process-Based Soil Formation Models With Digital Soil Mapping.

NASA Astrophysics Data System (ADS)

Vanwalleghem, T.; Román, A.; Peña, A.; Laguna, A.; Giráldez, J. V.

2017-12-01

There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties in the critical zone. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of traditional digital soil mapping versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

Interactive effects of a high-quality protein diet and high stocking density on the stress response and some innate immune parameters of Senegalese sole Solea senegalensis.

PubMed

Costas, Benjamín; Aragão, Cláudia; Dias, Jorge; Afonso, António; Conceição, Luís E C

2013-10-01

Amino acids (AA) regulate key metabolic pathways, including some immune responses. Therefore, this study aimed to assess whether an increased availability of dietary AA can mitigate the expected increase in plasma cortisol and metabolites levels due to high stocking density and its subsequent immunosuppression. Senegalese sole (Solea senegalensis) were maintained at low stocking density (LSD; 3.5 kg m(-2)) or high stocking density (HSD; 12 kg m(-2)) for 18 days. Additionally, both treatments were fed a control or a high protein (HP) diet (LSD, LSD HP, HSD and HSD HP). The HP diet slightly increased the levels of digestible indispensable AA, together with tyrosine and cysteine. HSD was effective in inducing a chronic stress response after 18 days of treatment since fish held at HSD presented higher plasma cortisol, glucose and lactate levels. Moreover, this increase in stress indicators translated in a decrease in plasma lysozyme, alternative complement pathway (ACP) and peroxidase activities, suggesting some degree of immunosuppression. Interestingly, while plasma glucose and lactate levels in HSD HP specimens decreased to similar values than LSD fish, plasma lysozyme, ACP and peroxidase activities increased, with even higher values than LSD groups for ACP activity. It is suggested that the HP diet may be used as functional feed since it may represent a metabolic advantage during stressful events and may counteract immunosuppression in sole.

76 FR 80993 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-27

... option of obtaining several cabinet sizes and power densities. The co-located customer may obtain a half cabinet, a low density cabinet, a medium density cabinet, a medium-high density cabinet and a high density...-location customer may obtain more power by choosing a combination of lower power density cabinets. However...

Pasture-derived greenhouse gas emissions in cow-calf production systems.

PubMed

Chiavegato, M B; Powers, W J; Carmichael, D; Rowntree, J E

2015-03-01

There is a lack of information regarding carbon dioxide (CO), methane (CH), and nitrous oxide (NO) emissions from pasture soils and the effects of grazing. The objective of this study was to quantify greenhouse gas (GHG) fluxes from pasture soils grazed with cow-calf pairs managed with different stocking rates and densities. The central hypothesis was that irrigated low-density stocking systems (SysB) would result in greater GHG emissions from pasture soils than nonirrigated high-density stocking systems (SysA) and grazing-exclusion (GRE) pasture sites. The nonirrigated high-density stocking systems consisted of 120 cow-calf pairs rotating on a total of 120 ha (stocking rate 1 cow/ha, stocking density 112,000 kg BW/ha, rest period of 60 to 90 d). The irrigated low-density stocking systems consisted of 64 cow-calf pairs rotating on a total of 26 ha of pasture (stocking rate 2.5 cows/ha, stocking density 32,700 kg BW/ha, rest period of 18 to 30 d). Both systems consisted of mixed cool-season grass-legume pastures. Static chambers were randomly placed for collection of CO, CH, and NO samples. Soil temperature (ST), ambient temperature (temperature inside the chamber; AT), and soil water content (WC) were monitored and considered explanatory variables for GHG emissions. GHG fluxes were monitored for 3 yr (2011 to 2013) at the beginning (P1) and at the end (P2) of the grazing season, always postgrazing. Paddock was the experimental unit (3 pseudoreplicates per treatment), and chambers (30 chambers per paddock) were considered multiple measurements of each experimental unit. A completely randomized design considered the term year × period as a repeated measure and chamber nested within paddock and treatment as the random term. Generally, SysB had greater CO emissions than SysA and GRE pasture sites across years and periods ( < 0.01). Soil temperature, AT, and WC had effects on CO emissions. Methane and NO emissions were observed from pasture sites of the 3 systems, but the effect of grazing was not constantly significant for CH and NO emissions. In addition, ST, AT, and WC did not conclusively explain CH and NO emissions. No clear trade-offs between GHG were observed; generally, GHG emissions increased from 2011 to 2013, which was likely associated with weather conditions, such as higher daily temperature and precipitation events. The central hypothesis that SysB would result in greater GHG emissions from pasture soils than SysA and GRE was not confirmed.

Unraveling vasotocinergic, isotocinergic and stress pathways after food deprivation and high stocking density in the gilthead sea bream.

PubMed

Skrzynska, Arleta Krystyna; Martos-Sitcha, Juan Antonio; Martínez-Rodríguez, Gonzalo; Mancera, Juan Miguel

2018-01-01

The influence of chronic stress, induced by food deprivation (FD) and/or high stocking density (HSD), was assessed on stress, vasotocinergic and isotocinergic pathways of the gilthead sea bream (Sparus aurata). Fish were randomly assigned to one of the following treatments: (1) fed at low stocking density (LSD-F; 5kg·m -3 ); (2) fed at high stocking density (HSD-F, 40kg·m -3 ); (3) food-deprived at LSD (LSD-FD); and (4) food-deprived at HSD (HSD-FD). After 21days, samples from plasma, liver, hypothalamus, pituitary and head-kidney were collected. Both stressors (FD and HSD) induced a chronic stress situation, as indicated by the elevated cortisol levels, the enhancement in corticotrophin releasing hormone (crh) expression and the down-regulation in corticotrophin releasing hormone binding protein (crhbp) expression. Changes in plasma and liver metabolites confirmed a metabolic adjustment to cope with energy demand imposed by stressors. Changes in avt and it gene expression, as well as in their specific receptors (avtrv1a, avtrv2 and itr) at central (hypothalamus and pituitary) and peripheral (liver and head-kidney) levels, showed that vasotocinergic and isotocinergic pathways are involved in physiological changes induced by FD or HSD, suggesting that different stressors are handled through different stress pathways in S. aurata. Copyright © 2017 Elsevier Inc. All rights reserved.

Stocking Density Optimization for Enhanced Bioconversion of Fly Ash Enriched Vermicompost.

PubMed

Mupambwa, Hupenyu A; Mnkeni, Pearson N S

2016-05-01

Although it is widely agreed that stocking density critically affects the rate of vermicomposting, there is no established stocking density for mixtures of fly ash and other waste materials. This study sought to optimize (Savigny, 1826) stocking density for effective biodegradation and nutrient release in a fly ash-cow dung-waste paper (FCP) mixture. Four stocking densities of 0, 12.5, 25, and 37.5 g worms kg were evaluated. Although the 12.5, 25, and 37.5 g worms kg treatments all resulted in a mature vermicompost, stocking densities of 25 and 37.5 g worms kg resulted in faster maturity, higher humification parameters, and a significantly lower final C/N ratio (range 11.1-10.4). The activity of β-glucosidase and fluorescein diacetate hydrolysis enzymes showed faster stabilization at stocking densities of 25 and 37.5 g worms kg, indicating compost stability and maturity. Similarly, a stocking density of 25 g worms kg resulted in the highest release of Olsen-extractable P and (NO + NO)-N contents. The 0-, 12.5-, 25-, and 37.5-g treatments resulted in net Olsen P increases of 16.3, 38.9, 61.0, and 53.0%, respectively, after 10 wk. Although compost maturity could be attained at stocking densities of 12.5 g worms kg, for faster production of humified and nutrient-rich FCP vermicompost, a stocking density of 25 g worms kg seems most appropriate. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Growth and yield of western larch: 15-year results of a levels-of-growing-stock study.

Treesearch

K.W. Seidel

1982-01-01

The 15-year growth response from a levels-of-growing-stock study in an even-aged western larch (Larix occidentalis Nutt.) stand in northeastern Oregon, first thinned at age 33, showed that trees growing at lower stand densities grew more rapidly in diameter but did not grow faster in height than trees in high density plots. Both basal area and...

Carbon stocks and potential carbon storage in the mangrove forests of China.

PubMed

Liu, Hongxiao; Ren, Hai; Hui, Dafeng; Wang, Wenqing; Liao, Baowen; Cao, Qingxian

2014-01-15

Mangrove forests provide important ecosystem services, and play important roles in terrestrial and oceanic carbon (C) cycling. Although the C stocks or storage in terrestrial ecosystems in China have been frequently assessed, the C stocks in mangrove forests have often been overlooked. In this study, we estimated the C stocks and the potential C stocks in China's mangrove forests by combining our own field data with data from the National Mangrove Resource Inventory Report and from other published literature. The results indicate that mangrove forests in China store about 6.91 ± 0.57 Tg C, of which 81.74% is in the top 1 m soil, 18.12% in the biomass of mangrove trees, and 0.08% in the ground layer (i.e. mangrove litter and seedlings). The potential C stocks are as high as 28.81 ± 4.16 Tg C. On average, mangrove forests in China contain 355.25 ± 82.19 Mg C ha(-1), which is consistent with the global average of mangrove C density at similar latitudes, but higher than the average C density in terrestrial forests in China. Our results suggest that C storage in mangroves can be increased by selecting high C-density species for afforestation and stand improvement, and even more by increasing the mangrove area. The information gained in this study will facilitate policy decisions concerning the restoration of mangrove forests in China. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of dietary probiotic and high stocking density on the performance, carcass yield, gut microflora, and stress indicators of broilers.

PubMed

Cengiz, Özcan; Köksal, Bekir H; Tatlı, Onur; Sevim, Ömer; Ahsan, Umair; Üner, Aykut G; Ulutaş, Pınar A; Beyaz, Devrim; Büyükyörük, Sadık; Yakan, Akın; Önol, Ahmet G

2015-10-01

A study was carried out to evaluate the effect of dietary probiotic supplementation and stocking density on the performance, relative carcass yield, gut microflora, and stress markers of broilers. One-day-old Ross 308 male broiler chickens (n = 480) were allocated to 4 experimental groups for 42 d. Each treatment had 8 replicates of 15 chicks each. Two groups were subjected to a high stocking density (HSD) of 20 birds/m² and the other 2 groups were kept at low stocking density (LSD) of 10 birds/m². A basal diet supplemented with probiotic 1 and 0.5 g/kg of diet (in starter and finisher diets, respectively) was fed to 2 treatments, one with HSD and the other with LSD, thereby making a 2 × 2 factorial arrangement. There was no interaction between stocking density (LSD and HSD) and dietary probiotic (supplemented and unsupplemented) for all the variables. Feed intake and weight gain were significantly low and feed conversion ratio was poor in broilers at HSD. Dietary probiotic significantly enhanced the feed intake and weight gain in starter phase only. Dietary probiotic supplementation had no effect (P > 0.05) on total aerobs, Salmonella sp., and Lactobacilli populations in the intestines of broilers. However, HSD reduced the Lactobacilli population only (P < 0.05). Relative breast yields were significantly higher in broilers reared at LSD than HSD. Thigh meat yield was higher in broilers in HSD group compared to LSD. Dietary probiotic did not affect the relative carcass yield and weight of lymphoid organs. Serum malondialdehyde, corticosterone, nitric oxide, and plasma heterophil:lymphocyte ratio were not affected either by stocking density or dietary probiotic supplementation. In conclusion, HSD negatively affected the performance and intestinal Lactobacilli population of broilers only, whereas probiotic supplementation enhanced the performance of broilers during the starter phase only. Total aerobes, Salmonella, Lactobacilli carcass yield, and stress indicators of broilers were not affected by the dietary supplementation of probiotic under the conditions of the present study. © 2015 Poultry Science Association Inc.

The risks and returns of stock investment in a financial market

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Mei, Dong-Cheng

2013-03-01

The risks and returns of stock investment are discussed via numerically simulating the mean escape time and the probability density function of stock price returns in the modified Heston model with time delay. Through analyzing the effects of delay time and initial position on the risks and returns of stock investment, the results indicate that: (i) There is an optimal delay time matching minimal risks of stock investment, maximal average stock price returns and strongest stability of stock price returns for strong elasticity of demand of stocks (EDS), but the opposite results for weak EDS; (ii) The increment of initial position recedes the risks of stock investment, strengthens the average stock price returns and enhances stability of stock price returns. Finally, the probability density function of stock price returns and the probability density function of volatility and the correlation function of stock price returns are compared with other literatures. In addition, good agreements are found between them.

The Effect of Different Feed and Stocking Densities on Growth And Survival Rate Of Blue Swimming Crablets (Portunus pelagicus)

NASA Astrophysics Data System (ADS)

Ariyati, R. W.; Rejeki, S.; Bosma, R. H.

2018-02-01

Blue swimming crab is targeted by commercial fisheries because of the high economic value, good taste, and attractive colors. As a result, the stock is overexploited and fisherman catch market also juveniles. The most sustainable solution would be to stop fishing for commercial trade and to culture this crab from brood to market size. This study aimed to find the best feed and stocking density for the on-growing of crablets. In 20 tanks juvenile crabs with a carapace width±1 cm were stocked in three densities; 40, 60 and 80 crablets / m2, and fed ad-libitum twice a day with either trash fish or pellets of shrimp feed, for 8 weeks. The circular (ᴓ 1.6 m x 1 m) tanks with 1 m3 of water were aerated, and temperature, salinity, dissolved oxygen and pH recorded daily. In the end, growth and survival rates were determined. In general, feeding the crablets at a density of 40 m-2 gave the highest growth. For crablest fed with pellets, the density of 40 m-2 gave significantly better growth than 80 m-2. The crablets at a density 40 m-2 having a fish diet with the density 40 m-2 grew better than 60 and 80 m-2. There was no significant difference between fed used among different densities. The lower densities resulted in higher survival, either on crablets fed with pellets or fish. But, crablets fed the fish diet and cultured in the lowest density (40 m-2) had the highest survival rate.

Design Difficulties in Stand Density Studies

Treesearch

Frank A. Bennett

1969-01-01

Designing unbiased stand density studies is difficult. An acceptable sample requires stratification of the plots of age, site, and density. When basal area, percent stocking, or Reineke's stand density index is used as the density measure, this stratification forces a high negative correlation between site and number of trees per acre. Mortality in trees per acre...

Outdoor stocking density in free-range laying hens: effects on behaviour and welfare.

PubMed

Campbell, D L M; Hinch, G N; Downing, J A; Lee, C

2017-06-01

Free-range laying hen systems are increasing within Australia and research is needed to determine optimal outdoor stocking densities. Six small (n=150 hens) experimental flocks of ISA Brown laying hens were housed with access to ranges simulating one of three outdoor stocking densities with two pen replicates per density: 2000 hens/ha, 10 000 hens/ha or 20 000 hens/ha. Birds were provided daily range access from 21 to 36 weeks of age and the range usage of 50% of hens was tracked using radio-frequency identification technology. Throughout the study, basic external health assessments following a modified version of the Welfare Quality® protocol showed most birds were in visibly good condition (although keel damage was increasingly present with age) with few differences between stocking densities. Toenail length at 36 weeks of age was negatively correlated with hours spent ranging for all pens of birds (all r⩾-0.23, P⩽0.04). At 23 weeks of age, there were no differences between outdoor stocking densities in albumen corticosterone concentrations (P=0.44). At 35 weeks of age, density effects were significant (P<0.001) where the eggs from hens in the highest outdoor stocking density showed the highest albumen corticosterone concentrations, although eggs from hens in the 10 000 hens/ha density showed the lowest concentrations (P<0.017). Behavioural observations of hens both on the range and indoors showed more dust bathing and foraging (scratching followed by ground-pecking) was performed outdoors, but more resting indoors (all P<0.001). Hens from the 2000 hens/ha densities showed the least foraging on the range but the most resting outdoors, with hens from the 20 000 hens/ha densities showing the least amount of resting outdoors (all P<0.017). Proportions of dust bathing outdoors tended to differ between the stocking densities (P=0.08). For each of the health and behavioural measures there were differences between pen replicates within stocking densities. These data show outdoor stocking density has some effects on hen welfare, and it appears that consideration of both individual and group-level behaviour is necessary when developing optimal stocking density guidelines and free-range system management practices.

Growing stock and woody biomass assessment in Asola-Bhatti Wildlife Sanctuary, Delhi, India.

PubMed

Kushwaha, S P S; Nandy, S; Gupta, Mohini

2014-09-01

Biomass is an important entity to understand the capacity of an ecosystem to sequester and accumulate carbon over time. The present study, done in collaboration with the Delhi Forest Department, focused on the estimation of growing stock and the woody biomass in the so-called lungs of Delhi--the Asola-Bhatti Wildlife Sanctuary in northern Aravalli hills. The satellite-derived vegetation strata were field-inventoried using stratified random sampling procedure. Growing stock was calculated for the individual sample plots using field data and species-specific volume equations. Biomass was estimated from the growing stock and the specific gravity of the wood. Among the four vegetation types, viz. Prosopis juliflora, Anogeissus pendula, forest plantation and the scrub, the P. juliflora was found to be the dominant vegetation in the area, covering 23.43 km(2) of the total area. The study revealed that P. juliflora forest with moderate density had the highest (10.7 m(3)/ha) while A. pendula forest with moderate density had the lowest (3.6 m(3)/ha) mean volume. The mean woody biomass was also found to be maximum in P. juliflora forest with moderate density (10.3 t/ha) and lowest in A. pendula forest with moderate density (3.48 t/ha). The total growing stock was estimated to be 20,772.95 m(3) while total biomass worked out to be 19,366.83 t. A strong correlation was noticed between the normalized difference vegetation index (NDVI) and the growing stock (R(2) = 0.84)/biomass (R(2) = 0.88). The study demonstrated that growing stock and the biomass of the woody vegetation in Asola-Bhatti Wildlife Sanctuary could be estimated with high accuracy using optical remote sensing data.

Effect of stocking density on performance, diet selection, total-tract digestion, and nitrogen balance among heifers grazing cool-season annual forages.

PubMed

Brunsvig, B R; Smart, A J; Bailey, E A; Wright, C L; Grings, E E; Brake, D W

2017-08-01

Grazing annual cool-season forages after oat grain harvest in South Dakota may allow an opportunity to increase efficient use of tillable land. However, data are limited regarding effects of stocking density on diet selection, nutrient digestion, performance, and N retention by cattle grazing annual cool-season forage. Heifers were blocked by initial BW (261 ± 11.7 kg) and randomly assigned to 1 of 12 paddocks (1.1 ha) to graze a mixture of grass and brassica for 48 d. Each paddock contained 3, 4, or 5 heifers to achieve 4 replicates of each stocking density treatment. Ruminally cannulated heifers were used to measure diet and nutrient intake. Effects of stocking density on diet and nutrient selection were measured after 2, 24, and 46 d of grazing, and BW was measured at the beginning, middle, and end of the experiment as the average of d 1 and 2, d 22 and 23, and d 47 and 48 BW, respectively. Measures of DMI and DM, OM, NDF, and ADF digestion were collected from d 18 to 23. Increased stocking density increased intake of brassica relative to grass on d 24 (quadratic, = 0.02), but increased stocking density decreased (linear, ≤ 0.01) intake of brassica compared with grass on d 48 (stocking density × time, < 0.01). Increased stocking density increased DM (quadratic, < 0.01), OM (quadratic, = 0.01), and NDF (quadratic, = 0.05) digestion, and stocking density tended to increase DMI (quadratic, = 0.07). Additionally, increased stocking density quadratically increased ( = 0.05) N retention but did not affect overall BW gains. Increased stocking density did, however, contribute to linearly decreased ( = 0.05) BW gains from d 1 to 22 of grazing, but BW gains during the latter half of the experiment were greater than BW gains from d 1 to 22. Ruminal concentration of acetate:propionate was least on d 24 of grazing, and ruminal nitrate concentration tended to linearly decrease ( = 0.06) with greater amounts of time on pasture. Ruminal liquid and particulate fill and amounts of VFA were less (quadratic, ≤ 0.01) with greater amounts of time on pasture. Apparently, binary mixtures of brassica and grass planted after oat grain harvest can provide an opportunity to increase efficient use of land by providing forage resources. Increased stocking density may facilitate a more rapid adaptation to and intake of brassica among cattle grazing brassica-grass-based pastures.

Effects of hatchery fish density on emigration, growth, survival, and predation risk of natural steelhead parr in an experimental stream channel

USGS Publications Warehouse

Tatara, Christopher P.; Riley, Stephen C.; Berejikian, Barry A.

2011-01-01

Hatchery supplementation of steelhead Oncorhynchus mykiss raises concerns about the impacts on natural populations, including reduced growth and survival, displacement, and increased predation. The potential risks may be density dependent.We examined how hatchery stocking density and the opportunity to emigrate affect the responses of natural steelhead parr in an experimental stream channel and after 15 d found no density-dependent effects on growth, emigration, or survival at densities ranging from 1-6 hatchery parr/m2. The opportunity for steelhead parr to emigrate reduced predation by coastal cutthroat trout O. clarkii clarkii on both hatchery and natural steelhead parr. The cutthroat trout exhibited a type-I functional response (constant predation rate with increased prey density) for the hatchery and composite populations. In contrast, the predation rate on natural parr decreased as hatchery stocking density increased. Supplementation with hatchery parr at any experimental stocking density reduced the final natural parr density. This decline was explained by increased emigration fromthe supplemented groups. Natural parr had higher mean instantaneous growth rates than hatchery parr. The proportion of parr emigrating decreased as parr size increased over successive experimental trials. Smaller parr had lower survival and suffered higher predation. The final density of the composite population, a measure of supplementation effectiveness, increased with the hatchery steelhead stocking rate. Our results indicate that stocking larger hatchery parr (over 50 d postemergence) at densities within the carrying capacity would have low short-term impact on the growth, survival, and emigration of natural parr while increasing the density of the composite population; in addition, a stocking density greater than 3 fish/m2 might be a good starting point for the evaluation of parr stocking in natural streams.

Predicting crappie recruitment in Ohio reservoirs with spawning stock size, larval density, and chlorophyll concentrations

USGS Publications Warehouse

Bunnell, David B.; Hale, R. Scott; Vanni, Michael J.; Stein, Roy A.

2006-01-01

Stock-recruit models typically use only spawning stock size as a predictor of recruitment to a fishery. In this paper, however, we used spawning stock size as well as larval density and key environmental variables to predict recruitment of white crappies Pomoxis annularis and black crappies P. nigromaculatus, a genus notorious for variable recruitment. We sampled adults and recruits from 11 Ohio reservoirs and larvae from 9 reservoirs during 1998-2001. We sampled chlorophyll as an index of reservoir productivity and obtained daily estimates of water elevation to determine the impact of hydrology on recruitment. Akaike's information criterion (AIC) revealed that Ricker and Beverton-Holt stock-recruit models that included chlorophyll best explained the variation in larval density and age-2 recruits. Specifically, spawning stock catch per effort (CPE) and chlorophyll explained 63-64% of the variation in larval density. In turn, larval density and chlorophyll explained 43-49% of the variation in age-2 recruit CPE. Finally, spawning stock CPE and chlorophyll were the best predictors of recruit CPE (i.e., 74-86%). Although larval density and recruitment increased with chlorophyll, neither was related to seasonal water elevation. Also, the AIC generally did not distinguish between Ricker and Beverton-Holt models. From these relationships, we concluded that crappie recruitment can be limited by spawning stock CPE and larval production when spawning stock sizes are low (i.e., CPE , 5 crappies/net-night). At higher levels of spawning stock sizes, spawning stock CPE and recruitment were less clearly related. To predict recruitment in Ohio reservoirs, managers should assess spawning stock CPE with trap nets and estimate chlorophyll concentrations. To increase crappie recruitment in reservoirs where recruitment is consistently poor, managers should use regulations to increase spawning stock size, which, in turn, should increase larval production and recruits to the fishery.

Stocking density affects the growth performance and metabolism of Amur sturgeon by regulating expression of genes in the GH/IGF axis

NASA Astrophysics Data System (ADS)

Ren, Yuanyuan; Wen, Haishen; Li, Yun; Li, Jifang

2017-07-01

The effects of stocking density on the growth and metabolism of Amur sturgeon were assessed. Amur sturgeon were grown for 70 days at three different stocking densities (low stocking density, LSD: 5.5 kg/m3; medium stocking density, MSD: 8.0 kg/m3; and high stocking density, HSD: 11.0 kg/m3), and the biometric index, muscle composition, and serum biochemical parameters were evaluated. In addition, pituitary, liver, and muscle samples were collected for gene cloning and expression analyses. After 70 days of growth, the fish maintained at HSD had significantly lower final body weight and specific growth rate, and a higher feed conversion ratio than those of the fish in the MSD and LSD groups. The HSD group had the lowest lipid and protein concentrations in serum and muscle. The serum cortisol concentration increased significantly in the HSD group, indicating that the stress-response system was activated in these fish. There was no change in the concentration of serum insulin-like growth factor 2 (IGF-2), while the concentrations of serum growth hormone (GH) and insulin-like growth factor 1 (IGF-1) decreased in the HSD group. The full-length cDNAs of GH and IGF-2 genes (995-bp and 1 207-bp long, respectively), were cloned and analyzed. In the HSD group, the expressions of GH in the pituitary and growth hormone receptor (GHR) and IGF-1 in the liver were down-regulated at the end of the 70-day experiment. In the HSD group, the transcript level of IGF-2 significantly decreased in the liver, but did not change in muscle. Overall, our results indicated that a HSD negatively affects the growth performance and leads to changes in lipid and protein metabolism in Amur sturgeon. The down-regulated expression of genes related to the GH/IGF axis may be responsible for the poor growth performance of Amur sturgeon under crowding stress.

Effects of rapid urban sprawl on urban forest carbon stocks: integrating remotely sensed, GIS and forest inventory data.

PubMed

Ren, Yin; Yan, Jing; Wei, Xiaohua; Wang, Yajun; Yang, Yusheng; Hua, Lizhong; Xiong, Yongzhu; Niu, Xiang; Song, Xiaodong

2012-12-30

Research on the effects of urban sprawl on carbon stocks within urban forests can help support policy for sustainable urban design. This is particularly important given climate change and environmental deterioration as a result of rapid urbanization. The purpose of this study was to quantify the effects of urban sprawl on dynamics of forest carbon stock and density in Xiamen, a typical city experiencing rapid urbanization in China. Forest resource inventory data collected from 32,898 patches in 4 years (1972, 1988, 1996 and 2006), together with remotely sensed data (from 1988, 1996 and 2006), were used to investigate vegetation carbon densities and stocks in Xiamen, China. We classified the forests into four groups: (1) forest patches connected to construction land; (2) forest patches connected to farmland; (3) forest patches connected to both construction land and farmland and (4) close forest patches. Carbon stocks and densities of four different types of forest patches during different urbanization periods in three zones (urban core, suburb and exurb) were compared to assess the impact of human disturbance on forest carbon. In the urban core, the carbon stock and carbon density in all four forest patch types declined over the study period. In the suburbs, different urbanization processes influenced forest carbon density and carbon stock in all four forest patch types. Urban sprawl negatively affected the surrounding forests. In the exurbs, the carbon stock and carbon density in all four forest patch types tended to increase over the study period. The results revealed that human disturbance played the dominant role in influencing the carbon stock and density of forest patches close to the locations of human activities. In forest patches far away from the locations of human activities, natural forest regrowth was the dominant factor affecting carbon stock and density. Copyright © 2012 Elsevier Ltd. All rights reserved.

On the emergence of a generalised Gamma distribution. Application to traded volume in financial markets

NASA Astrophysics Data System (ADS)

Duarte Queirós, S. M.

2005-08-01

This letter reports on a stochastic dynamical scenario whose associated stationary probability density function is exactly a generalised form, with a power law instead of exponencial decay, of the ubiquitous Gamma distribution. This generalisation, also known as F-distribution, was empirically proposed for the first time to adjust for high-frequency stock traded volume distributions in financial markets and verified in experiments with granular material. The dynamical assumption presented herein is based on local temporal fluctuations of the average value of the observable under study. This proposal is related to superstatistics and thus to the current nonextensive statistical mechanics framework. For the specific case of stock traded volume, we connect the local fluctuations in the mean stock traded volume with the typical herding behaviour presented by financial traders. Last of all, NASDAQ 1 and 2 minute stock traded volume sequences and probability density functions are numerically reproduced.

77 FR 28415 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

... Proposed Rule Change To Modify the NASDAQ Co-Location Super High Density Cabinet Monthly Fee May 8, 2012...- density cabinet monthly fee. The Exchange will implement the proposed change on May 1, 2012. The text of... The Exchange is modifying Rule 7034(a) by reducing its co-location super high-density cabinet on-going...

Carbon pool densities and a first estimate of the total carbon pool in the Mongolian forest-steppe.

PubMed

Dulamsuren, Choimaa; Klinge, Michael; Degener, Jan; Khishigjargal, Mookhor; Chenlemuge, Tselmeg; Bat-Enerel, Banzragch; Yeruult, Yolk; Saindovdon, Davaadorj; Ganbaatar, Kherlenchimeg; Tsogtbaatar, Jamsran; Leuschner, Christoph; Hauck, Markus

2016-02-01

The boreal forest biome represents one of the most important terrestrial carbon stores, which gave reason to intensive research on carbon stock densities. However, such an analysis does not yet exist for the southernmost Eurosiberian boreal forests in Inner Asia. Most of these forests are located in the Mongolian forest-steppe, which is largely dominated by Larix sibirica. We quantified the carbon stock density and total carbon pool of Mongolia's boreal forests and adjacent grasslands and draw conclusions on possible future change. Mean aboveground carbon stock density in the interior of L. sibirica forests was 66 Mg C ha(-1) , which is in the upper range of values reported from boreal forests and probably due to the comparably long growing season. The density of soil organic carbon (SOC, 108 Mg C ha(-1) ) and total belowground carbon density (149 Mg C ha(-1) ) are at the lower end of the range known from boreal forests, which might be the result of higher soil temperatures and a thinner permafrost layer than in the central and northern boreal forest belt. Land use effects are especially relevant at forest edges, where mean carbon stock density was 188 Mg C ha(-1) , compared with 215 Mg C ha(-1) in the forest interior. Carbon stock density in grasslands was 144 Mg C ha(-1) . Analysis of satellite imagery of the highly fragmented forest area in the forest-steppe zone showed that Mongolia's total boreal forest area is currently 73 818 km(2) , and 22% of this area refers to forest edges (defined as the first 30 m from the edge). The total forest carbon pool of Mongolia was estimated at ~ 1.5-1.7 Pg C, a value which is likely to decrease in future with increasing deforestation and fire frequency, and global warming. © 2015 John Wiley & Sons Ltd.

Infectivity and RNA patterns as functions of high- and low-dilution passage of murine sarcoma-leukemia virus: evidence for autointerference within an oncornavirus population.

PubMed

Bondurant, M C; Hackett, A J; Schaffer, F L

1973-05-01

Heterogeneity of buoyant density and RNA content of virions of Moloney murine leukemia-sarcoma complex [MSV (MLV)] was the result of passage at low dilution. Heterogeneous stocks revealed two major RNA components in the population, with the smaller component, apparent mol wt 4 x 10(6) to 5 x 10(6), becoming predominant upon serial passage at low dilution. Concomitantly, infectivity titers of both MLV and MSV decreased upon serial passage at low dilution. MSV (MLV) passaged at high dilution retained high titers and a rather homogeneous high-molecular-weight RNA population characteristic of high-buoyant-density virions. Interference of both MLV and MSV replication was demonstrated by employing mixed inocula containing both low- and high-dilution passage stocks of MSV (MLV). In contrast to results with MSV (MLV), MLV freed of MSV by limit dilution did not show heterogeneity of buoyant density or of RNA when propagated at low dilution.

Infectivity and RNA Patterns as Functions of High- and Low-Dilution Passage of Murine Sarcoma-Leukemia Virus: Evidence for Autointerference Within an Oncornavirus Population

PubMed Central

Bondurant, M. C.; Hackett, A. J.; Schaffer, F. L.

1973-01-01

Heterogeneity of buoyant density and RNA content of virions of Moloney murine leukemia-sarcoma complex [MSV (MLV)] was the result of passage at low dilution. Heterogeneous stocks revealed two major RNA components in the population, with the smaller component, apparent mol wt 4 × 106 to 5 × 106, becoming predominant upon serial passage at low dilution. Concomitantly, infectivity titers of both MLV and MSV decreased upon serial passage at low dilution. MSV (MLV) passaged at high dilution retained high titers and a rather homogeneous high-molecular-weight RNA population characteristic of high-buoyant-density virions. Interference of both MLV and MSV replication was demonstrated by employing mixed inocula containing both low- and high-dilution passage stocks of MSV (MLV). In contrast to results with MSV (MLV), MLV freed of MSV by limit dilution did not show heterogeneity of buoyant density or of RNA when propagated at low dilution. PMID:4350709

Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. II: live weight, health measures and perching.

PubMed

Steenfeldt, S; Nielsen, B L

2015-09-01

Multi-tier aviary systems, where conveyor belts below the tiers remove the manure at regular intervals, are becoming more common in organic egg production. The area on the tiers can be included in the net area available to the hens (also referred to as usable area) when calculating maximum indoor stocking densities in organic systems within the EU. In this article, results on live weight, health measures and perching are reported for organic laying hens housed in a multi-tier system with permanent access to a veranda and kept at stocking densities (D) of 6, 9 and 12 hens/m2 available floor area, with concomitant increases in the number of hens per trough, drinker, perch and nest space. In a fourth treatment, access to the top tier was blocked reducing vertical, trough, and perch access at the lowest stocking density (D6x). In all other aspects than stocking density, the experiment followed the EU regulations on the keeping of organic laying hens. Hen live weight, mortality and foot health were not affected by the stocking densities used in the present study. Other variables (plumage condition, presence of breast redness and blisters, pecked tail feathers, and perch use) were indirectly affected by the increase in stocking density through the simultaneous reduction in access to other resources, mainly perches and troughs. The welfare of the hens was mostly affected by these associated constraints, despite all of them being within the allowed minimum requirements for organic production in the EU. Although the welfare consequences reported here were assessed to be moderate to minor, it is important to take into account concurrent constraints on access to other resources when higher stocking densities are used in organic production.

Stocking equations for regeneration in mixed oak stands

Treesearch

Songlin Fei; Kim C. Steiner; James C. Finley

2007-01-01

Regeneration stocking equations for mixed-oak stands were developed based on data collected from nearly 14,000 plots in the central Appalachians. Maximum stand density was identified by plotting aggregate height against number of seedlings per plot, and was used as the reference level of the average maximum stand density (100 percent stocking or A-level stocking)....

Climatic and topographical factors affecting the vegetative carbon stock of rangelands in arid and semiarid regions of China

USGS Publications Warehouse

Zhengchao, Ren; Huazhong, Zhu; Shi, Hua; Xiaoni, Liu

2016-01-01

Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topographical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI (normalized difference vegetation index) time series datasets from 2001–2012. An improved CASA (Carnegie Ames Stanford Approach) model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4× 1014 gC, increasing linearly at an annual rate of 9.8×1011 gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500–3500 m, a slope of >30°and easterly aspect. The effect of precipitation, temperature and solar radiation on the vegetative carbon density of five rangeland types (desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest) depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for explaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.

Behavior of steelhead fry in a laboratory stream is affected by fish density but not rearing environment

USGS Publications Warehouse

Riley, Stephen C.; Tatara, Christopher P.; Berejikian, Barry A.; Flagg, Thomas A.

2009-01-01

We quantified the aggression, feeding, dominance, position choice, and territory size of naturally reared steelhead Oncorhynchus mykiss fry stocked with two types of hatchery-reared fry (from conventional and enriched rearing environments) at two densities in experimental flumes to determine how rearing environment and fish density affect the behavior of steelhead fry. We found that fry density had a significant effect on most response variables but that rearing treatment did not. The rates of threats and attacks were positively correlated with fry density, but the overall feeding rate was negatively correlated. Naturally reared fry were dominant more often at low densities, and hatchery-reared fry were dominant more often at high densities. There were no significant effects of hatchery rearing treatment on aggression, feeding, dominance, or territory size. The only significant effect of rearing treatment was on the position of naturally reared fry, which occupied more upstream positions when stocked with conventional than with enriched hatchery-reared fry. Overall, rearing environment had relatively little influence on the behavior of steelhead fry. Our results indicate that stocking hatchery-reared steelhead fry at low densities may have effects on similar-size wild fish comparable to an equivalent increase in the density of wild fish. We suggest that releasing hatchery-reared steelhead fry as a supplementation strategy may have few direct negative ecological effects on wild fry.

Limited carbon and biodiversity co-benefits for tropical forest mammals and birds.

PubMed

Beaudrot, Lydia; Kroetz, Kailin; Alvarez-Loayza, Patricia; Amaral, Eda; Breuer, Thomas; Fletcher, Christine; Jansen, Patrick A; Kenfack, David; Lima, Marcela Guimarães Moreira; Marshall, Andrew R; Martin, Emanuel H; Ndoundou-Hockemba, Mireille; O'Brien, Timothy; Razafimahaimodison, Jean Claude; Romero-Saltos, Hugo; Rovero, Francesco; Roy, Cisquet Hector; Sheil, Douglas; Silva, Carlos E F; Spironello, Wilson Roberto; Valencia, Renato; Zvoleff, Alex; Ahumada, Jorge; Andelman, Sandy

2016-06-01

The conservation of tropical forest carbon stocks offers the opportunity to curb climate change by reducing greenhouse gas emissions from deforestation and simultaneously conserve biodiversity. However, there has been considerable debate about the extent to which carbon stock conservation will provide benefits to biodiversity in part because whether forests that contain high carbon density in their aboveground biomass also contain high animal diversity is unknown. Here, we empirically examined medium to large bodied ground-dwelling mammal and bird (hereafter "wildlife") diversity and carbon stock levels within the tropics using camera trap and vegetation data from a pantropical network of sites. Specifically, we tested whether tropical forests that stored more carbon contained higher wildlife species richness, taxonomic diversity, and trait diversity. We found that carbon stocks were not a significant predictor for any of these three measures of diversity, which suggests that benefits for wildlife diversity will not be maximized unless wildlife diversity is explicitly taken into account; prioritizing carbon stocks alone will not necessarily meet biodiversity conservation goals. We recommend conservation planning that considers both objectives because there is the potential for more wildlife diversity and carbon stock conservation to be achieved for the same total budget if both objectives are pursued in tandem rather than independently. Tropical forests with low elevation variability and low tree density supported significantly higher wildlife diversity. These tropical forest characteristics may provide more affordable proxies of wildlife diversity for future multi-objective conservation planning when fine scale data on wildlife are lacking.

Effects of different rearing systems on growth, small intestinal morphology and selected indices of fermentation status in broilers.

PubMed

Li, Jianhui; Miao, Zhiqiang; Tian, Wenxia; Yang, Yu; Wang, Jundong; Yang, Ying

2017-06-01

A 3×2 factorial experiment was conducted to determine the effects of rearing system and stocking density on the growth performance, intestinal morphology and fermentation status of broilers. Broilers were kept on three rearing systems: floor litter rearing (FRS), plastic net rearing (NRS) and multilayer cage rearing system (CRS), each with two stocking densities (normal and high stocking densities). Results showed that on 7 to 28 days of age, body weight gain appeared as FRS > NRS > CRS. Whereas, CRS significantly enhanced the weight gain of broilers compared with the other systems subsequently. Broilers on FRS had higher counts of cecum Bifidobacteria and Lactobacilli at 28 days of age but had more Escherichia coli and less Bifidobacteria than CRS at 42 days of age. The FRS also decreased volatile fatty acid (VFA) concentration and jejunal villus height-to-crypt depth ratio at all ages. In conclusion, FRS appeared to benefit gut microorganisms during the early growing period along with high body weight gain of broilers, whereas this system might have a harmful effect on subsequent intestinal growth, as indicated by high E. coli, low Bifidobacteria count, low VFA concentration and villus height-to-crypt depth ratio along with low weight gain of broilers. © 2016 Japanese Society of Animal Science.

Effects of stocking density, light and perches on broiler growth.

PubMed

Velo, Ramón; Ceular, Angel

2017-02-01

The aim of this study was to determine the effect of stocking density, light intensity and light color on broiler growth. The experiment consisted of four 35-day phases during each of which 320 chickens were surveyed. The research was performed at stocking densities of four and six birds/m 2 . Illuminances of 15 and 30 lx were obtained through commercial lamps with 4000 K and 6000 K color temperatures. Lighting was used 17 h a day, between 06.00 and 23.00 hours (17 L:7 D). The results showed a decrease in body, carcass, breast and thighs weight (P < 0.05) with the increase in stocking density. Body weight decreased by 10.5% and carcass weight decreased by 9.4% at six birds/m 2 stocking density. Contrastingly, no differences were found for the tested light colors. Increasing illuminance from 15 to 30 lx caused a 1.9% decrease in body weight. The analysis of the effect of perches revealed that using perches significantly increased body (2.5%) and breast weight (11.8%). The interactions between light intensity or color and stocking density and between light intensity and light color were analyzed. © 2016 Japanese Society of Animal Science.

Bivariate sub-Gaussian model for stock index returns

NASA Astrophysics Data System (ADS)

Jabłońska-Sabuka, Matylda; Teuerle, Marek; Wyłomańska, Agnieszka

2017-11-01

Financial time series are commonly modeled with methods assuming data normality. However, the real distribution can be nontrivial, also not having an explicitly formulated probability density function. In this work we introduce novel parameter estimation and high-powered distribution testing methods which do not rely on closed form densities, but use the characteristic functions for comparison. The approach applied to a pair of stock index returns demonstrates that such a bivariate vector can be a sample coming from a bivariate sub-Gaussian distribution. The methods presented here can be applied to any nontrivially distributed financial data, among others.

Asymptotic Behavior of the Stock Price Distribution Density and Implied Volatility in Stochastic Volatility Models

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

Gulisashvili, Archil, E-mail: guli@math.ohiou.ed; Stein, Elias M., E-mail: stein@math.princeton.ed

2010-06-15

We study the asymptotic behavior of distribution densities arising in stock price models with stochastic volatility. The main objects of our interest in the present paper are the density of time averages of the squared volatility process and the density of the stock price process in the Stein-Stein and the Heston model. We find explicit formulas for leading terms in asymptotic expansions of these densities and give error estimates. As an application of our results, sharp asymptotic formulas for the implied volatility in the Stein-Stein and the Heston model are obtained.

Relative contribution of stocked walleyes in Tennessee reservoirs

USGS Publications Warehouse

Vandergoot, C.S.; Bettoli, P.W.

2003-01-01

Since the mid-1950s, fisheries biologists with the Tennessee Wildlife Resources Agency have stocked walleyes Stizostedion vitreum in several tributary reservoirs of the Cumberland and Tennessee rivers to augment declining native stocks; however, the efficacy of these management actions has never been formally evaluated. The contribution of stocked walleyes in four Tennessee reservoirs was evaluated during 1999 and 2000 by marking fry and fingerlings through oxytetracycline (OTC) immersion. Stocking densities were 13-48 fingerlings/ha, and marking efficacy was high for fish marked as fry (mean = 98%; SE = 1.7%) and fingerlings (mean = 99%; SE = 0.6%). Nearly all (94-100%; N = 509) of the age-1 and age-2 walleyes collected in the four reservoirs were OTC-marked. Based on these findings, fingerling walleyes must be stocked annually to sustain the walleye populations in these tributary impoundments.

Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes.

PubMed

Eikeset, Anne Maria; Dunlop, Erin S; Heino, Mikko; Storvik, Geir; Stenseth, Nils C; Dieckmann, Ulf

2016-12-27

The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world's largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock's feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population's age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock's historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide.

Effects of livestock species and stocking density on accretion rates in grazed salt marshes

NASA Astrophysics Data System (ADS)

Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

2015-01-01

Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management decisions of salt marshes. In our study accretion rates were higher than the current SLR. Further research is needed to include grazing effects into sedimentation models, given the importance of grazing management in the Wadden Sea area.

Forest biomass density across large climate gradients in northern South America is related to water availability but not with temperature

PubMed Central

Cayuela, Luis; González-Caro, Sebastián; Aldana, Ana M.; Stevenson, Pablo R.; Phillips, Oliver; Cogollo, Álvaro; Peñuela, Maria C.; von Hildebrand, Patricio; Jiménez, Eliana; Melo, Omar; Londoño-Vega, Ana Catalina; Mendoza, Irina; Velásquez, Oswaldo; Fernández, Fernando; Serna, Marcela; Velázquez-Rua, Cesar; Benítez, Doris; Rey-Benayas, José M.

2017-01-01

Understanding and predicting the likely response of ecosystems to climate change are crucial challenges for ecology and for conservation biology. Nowhere is this challenge greater than in the tropics as these forests store more than half the total atmospheric carbon stock in their biomass. Biomass is determined by the balance between biomass inputs (i.e., growth) and outputs (mortality). We can expect therefore that conditions that favor high growth rates, such as abundant water supply, warmth, and nutrient-rich soils will tend to correlate with high biomass stocks. Our main objective is to describe the patterns of above ground biomass (AGB) stocks across major tropical forests across climatic gradients in Northwestern South America. We gathered data from 200 plots across the region, at elevations ranging between 0 to 3400 m. We estimated AGB based on allometric equations and values for stem density, basal area, and wood density weighted by basal area at the plot-level. We used two groups of climatic variables, namely mean annual temperature and actual evapotranspiration as surrogates of environmental energy, and annual precipitation, precipitation seasonality, and water availability as surrogates of water availability. We found that AGB is more closely related to water availability variables than to energy variables. In northwest South America, water availability influences carbon stocks principally by determining stand structure, i.e. basal area. When water deficits increase in tropical forests we can expect negative impact on biomass and hence carbon storage. PMID:28301482

Forest biomass density across large climate gradients in northern South America is related to water availability but not with temperature.

PubMed

Álvarez-Dávila, Esteban; Cayuela, Luis; González-Caro, Sebastián; Aldana, Ana M; Stevenson, Pablo R; Phillips, Oliver; Cogollo, Álvaro; Peñuela, Maria C; von Hildebrand, Patricio; Jiménez, Eliana; Melo, Omar; Londoño-Vega, Ana Catalina; Mendoza, Irina; Velásquez, Oswaldo; Fernández, Fernando; Serna, Marcela; Velázquez-Rua, Cesar; Benítez, Doris; Rey-Benayas, José M

2017-01-01

Understanding and predicting the likely response of ecosystems to climate change are crucial challenges for ecology and for conservation biology. Nowhere is this challenge greater than in the tropics as these forests store more than half the total atmospheric carbon stock in their biomass. Biomass is determined by the balance between biomass inputs (i.e., growth) and outputs (mortality). We can expect therefore that conditions that favor high growth rates, such as abundant water supply, warmth, and nutrient-rich soils will tend to correlate with high biomass stocks. Our main objective is to describe the patterns of above ground biomass (AGB) stocks across major tropical forests across climatic gradients in Northwestern South America. We gathered data from 200 plots across the region, at elevations ranging between 0 to 3400 m. We estimated AGB based on allometric equations and values for stem density, basal area, and wood density weighted by basal area at the plot-level. We used two groups of climatic variables, namely mean annual temperature and actual evapotranspiration as surrogates of environmental energy, and annual precipitation, precipitation seasonality, and water availability as surrogates of water availability. We found that AGB is more closely related to water availability variables than to energy variables. In northwest South America, water availability influences carbon stocks principally by determining stand structure, i.e. basal area. When water deficits increase in tropical forests we can expect negative impact on biomass and hence carbon storage.

Effects of stocking density on growth performance, carcass traits, and foot pad lesions of White Pekin ducks.

PubMed

Xie, M; Jiang, Y; Tang, J; Wen, Z G; Huang, W; Hou, S S

2014-07-01

Two experiments were conducted to study the effects of stocking density on growth performance, carcass yield, and foot pad lesions of White Pekin ducks from hatch to 14 d of age (experiment 1) and from 14 to 42 d of age (experiment 2), respectively. All ducks were reared in raised plastic wire-floor pens with a pen size of 30 m(2), and males and females were mixed at a ratio of 1:1 in each pen of both experiments. In experiment 1, a total of 10,200 ducks that were 1 d old were allotted to 20 pens according to the stocking densities of 13, 15, 17, 19, and 21 birds/m(2) (or 8.4, 9.7, 10.9, 11.9, and 13.0 kg of actually achieved BW/m(2)), respectively, with 4 replicates per treatment. In experiment 2, a total of 3,150 ducks that were 14 d old were allotted to 15 pens according to the stocking densities of 5, 6, 7, 8, and 9 birds/m(2) (or 17.0, 20.3, 23.6, 26.9, and 29.9 kg of actually achieved BW/m(2)), respectively, with 3 replicates per treatment. The stocking density had significant effects on final BW and weight gain of starter and growing ducks (P < 0.05), but not on feed/gain and mortality in both periods (P > 0.05). The final BW and weight gain of starter and growing ducks all decreased with increasing density (P < 0.05). Final BW and weight gain of starter ducks were reduced significantly as stocking density increased from 17 to 21 birds/m(2) (P < 0.05). In addition, final BW and weight gain of growing ducks decreased significantly when stocking density was 9 birds/m(2) (P < 0.05). On the other hand, increasing stocking density did not markedly influence the carcass, breast meat, leg meat, abdominal fat, and foot pad lesions of growing ducks (P > 0.05). © 2014 Poultry Science Association Inc.

Relative density: the key to stocking assessment in regional analysis—a forest survey viewpoint.

Treesearch

Colin D. MacLean

1979-01-01

Relative density is a measure of tree crowding compared to a reference level such as normal density. This stand attribute, when compared to management standards, indicates adequacy of stocking. The Pacific Coast Forest Survey Unit assesses the relative density of each stand sampled by summing the individual density contributions of each tree tallied, thus quantifying...

Optimal-rearing density for head-starting green turtles (Chelonia mydas Linnaeus, 1758).

PubMed

Kanghae, Hirun; Thongprajukaew, Karun; Jatupornpitukchat, Sasiporn; Kittiwattanawong, Kongkiat

2016-09-01

While ex situ conservation programs of juvenile green turtles (Chelonia mydas Linnaeus, 1758), before release to natural habitats, have been conducted in several countries, the optimal-stocking density for husbandry has not yet been reported. The optimization of stocking density was the main purpose of this study. The 15-day-old post-hatching turtles (29.30 ± 0.05 g body weight) were reared in round fiberglass tanks at various stocking densities including 20 turtles/m 3 (20TM), 40 turtles/m 3 (40TM), 60 turtles/m 3 (60TM), and 80 turtles/m 3 (80TM), over an 8-week trial. Water quality, survival, growth performance, feed utilization, aggressive behavior, fecal digestive enzymes, and hematological parameters were compared between the treatments, and were used as indicators of a successful captive rearing program. The water quality across the four treatments was in the standard range, but a high-stocking density reduced the quality significantly. No mortality was observed in any treatment group. Superior growth and feed utilization were only observed with the 40TM treatment, relative to the others (P < 0.05). The turtles in this group had no aggressive behavior, as indicated by observing hind limb biting. This treatment manipulated the level of proteolytic activity of pepsin and trypsin in response to density stressor, but not amylase, lipase, and chymotrypsin. The 40TM treatment also maintained the hematological characteristics, indicating no negative effects on health status. Overall, the findings indicate that the captivity program of post-hatching turtles at 40 turtles/m 3 is the preferred option in their head-started propagation, as well as in public displays in zoos or aquaria. Zoo Biol. 35:454-461, 2016. © Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Bioenergetics estimate of the effects of stocking density on hatchery production of smallmouth bass fingerlings

USGS Publications Warehouse

Robel, G.L.; Fisher, W.L.

1999-01-01

Production of and consumption by hatchery-reared tingerling (age-0) smallmouth bass Micropterus dolomieu at various simulated stocking densities were estimated with a bioenergetics model. Fish growth rates and pond water temperatures during the 1996 growing season at two hatcheries in Oklahoma were used in the model. Fish growth and simulated consumption and production differed greatly between the two hatcheries, probably because of differences in pond fertilization and mortality rates. Our results suggest that appropriate stocking density depends largely on prey availability as affected by pond fertilization and on fingerling mortality rates. The bioenergetics model provided a useful tool for estimating production at various stocking density rates. However, verification of physiological parameters for age-0 fish of hatchery-reared species is needed.

Economic Risk of Bee Pollination in Maine Wild Blueberry, Vaccinium angustifolium.

PubMed

Asare, Eric; Hoshide, Aaron K; Drummond, Francis A; Criner, George K; Chen, Xuan

2017-10-01

Recent pollinator declines highlight the importance of evaluating economic risk of agricultural systems heavily dependent on rented honey bees or native pollinators. Our study analyzed variability of native bees and honey bees, and the risks these pose to profitability of Maine's wild blueberry industry. We used cross-sectional data from organic, low-, medium-, and high-input wild blueberry producers in 1993, 1997-1998, 2005-2007, and from 2011 to 2015 (n = 162 fields). Data included native and honey bee densities (count/m2/min) and honey bee stocking densities (hives/ha). Blueberry fruit set, yield, and honey bee hive stocking density models were estimated. Fruit set is impacted about 1.6 times more by native bees than honey bees on a per bee basis. Fruit set significantly explained blueberry yield. Honey bee stocking density in fields predicted honey bee foraging densities. These three models were used in enterprise budgets for all four systems from on-farm surveys of 23 conventional and 12 organic producers (2012-2013). These budgets formed the basis of Monte Carlo simulations of production and profit. Stochastic dominance of net farm income (NFI) cumulative distribution functions revealed that if organic yields are high enough (2,345 kg/ha), organic systems are economically preferable to conventional systems. However, if organic yields are lower (724 kg/ha), it is riskier with higher variability of crop yield and NFI. Although medium-input systems are stochastically dominant with lower NFI variability compared with other conventional systems, the high-input system breaks even with the low-input system if honey bee hive rental prices triple in the future. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Long-term decline in krill stock and increase in salps within the Southern Ocean.

PubMed

Atkinson, Angus; Siegel, Volker; Pakhomov, Evgeny; Rothery, Peter

2004-11-04

Antarctic krill (Euphausia superba) and salps (mainly Salpa thompsoni) are major grazers in the Southern Ocean, and krill support commercial fisheries. Their density distributions have been described in the period 1926-51, while recent localized studies suggest short-term changes. To examine spatial and temporal changes over larger scales, we have combined all available scientific net sampling data from 1926 to 2003. This database shows that the productive southwest Atlantic sector contains >50% of Southern Ocean krill stocks, but here their density has declined since the 1970s. Spatially, within their habitat, summer krill density correlates positively with chlorophyll concentrations. Temporally, within the southwest Atlantic, summer krill densities correlate positively with sea-ice extent the previous winter. Summer food and the extent of winter sea ice are thus key factors in the high krill densities observed in the southwest Atlantic Ocean. Krill need the summer phytoplankton blooms of this sector, where winters of extensive sea ice mean plentiful winter food from ice algae, promoting larval recruitment and replenishing the stock. Salps, by contrast, occupy the extensive lower-productivity regions of the Southern Ocean and tolerate warmer water than krill. As krill densities decreased last century, salps appear to have increased in the southern part of their range. These changes have had profound effects within the Southern Ocean food web.

Extension of biomass estimates to pre-assessment periods using density dependent surplus production approach.

PubMed

Horbowy, Jan; Tomczak, Maciej T

2017-01-01

Biomass reconstructions to pre-assessment periods for commercially important and exploitable fish species are important tools for understanding long-term processes and fluctuation on stock and ecosystem level. For some stocks only fisheries statistics and fishery dependent data are available, for periods before surveys were conducted. The methods for the backward extension of the analytical assessment of biomass for years for which only total catch volumes are available were developed and tested in this paper. Two of the approaches developed apply the concept of the surplus production rate (SPR), which is shown to be stock density dependent if stock dynamics is governed by classical stock-production models. The other approach used a modified form of the Schaefer production model that allows for backward biomass estimation. The performance of the methods was tested on the Arctic cod and North Sea herring stocks, for which analytical biomass estimates extend back to the late 1940s. Next, the methods were applied to extend biomass estimates of the North-east Atlantic mackerel from the 1970s (analytical biomass estimates available) to the 1950s, for which only total catch volumes were available. For comparison with other methods which employs a constant SPR estimated as an average of the observed values, was also applied. The analyses showed that the performance of the methods is stock and data specific; the methods that work well for one stock may fail for the others. The constant SPR method is not recommended in those cases when the SPR is relatively high and the catch volumes in the reconstructed period are low.

Extension of biomass estimates to pre-assessment periods using density dependent surplus production approach

PubMed Central

Horbowy, Jan

2017-01-01

Biomass reconstructions to pre-assessment periods for commercially important and exploitable fish species are important tools for understanding long-term processes and fluctuation on stock and ecosystem level. For some stocks only fisheries statistics and fishery dependent data are available, for periods before surveys were conducted. The methods for the backward extension of the analytical assessment of biomass for years for which only total catch volumes are available were developed and tested in this paper. Two of the approaches developed apply the concept of the surplus production rate (SPR), which is shown to be stock density dependent if stock dynamics is governed by classical stock-production models. The other approach used a modified form of the Schaefer production model that allows for backward biomass estimation. The performance of the methods was tested on the Arctic cod and North Sea herring stocks, for which analytical biomass estimates extend back to the late 1940s. Next, the methods were applied to extend biomass estimates of the North-east Atlantic mackerel from the 1970s (analytical biomass estimates available) to the 1950s, for which only total catch volumes were available. For comparison with other methods which employs a constant SPR estimated as an average of the observed values, was also applied. The analyses showed that the performance of the methods is stock and data specific; the methods that work well for one stock may fail for the others. The constant SPR method is not recommended in those cases when the SPR is relatively high and the catch volumes in the reconstructed period are low. PMID:29131850

Carbon - Bulk Density Relationships for Highly Weathered Soils of the Americas

NASA Astrophysics Data System (ADS)

Nave, L. E.

2014-12-01

Soils are dynamic natural bodies composed of mineral and organic materials. As a result of this mixed composition, essential properties of soils such as their apparent density, organic and mineral contents are typically correlated. Negative relationships between bulk density (Db) and organic matter concentration provide well-known examples across a broad range of soils, and such quantitative relationships among soil properties are useful for a variety of applications. First, gap-filling or data interpolation often are necessary to develop large soil carbon (C) datasets; furthermore, limitations of access to analytical instruments may preclude C determinations for every soil sample. In such cases, equations to derive soil C concentrations from basic measures of soil mass, volume, and density offer significant potential for purposes of soil C stock estimation. To facilitate estimation of soil C stocks on highly weathered soils of the Americas, I used observations from the International Soil Carbon Network (ISCN) database to develop carbon - bulk density prediction equations for Oxisols and Ultisols. Within a small sample set of georeferenced Oxisols (n=89), 29% of the variation in A horizon C concentrations can be predicted from Db. Including the A-horizon sand content improves predictive capacity to 35%. B horizon C concentrations (n=285) were best predicted by Db and clay content, but were more variable than A-horizons (only 10% of variation explained by linear regression). Among Ultisols, a larger sample set allowed investigation of specific horizons of interest. For example, C concentrations of plowed A (Ap) horizons are predictable based on Db, sand and silt contents (n=804, r2=0.38); gleyed argillic (Btg) horizon concentrations are predictable from Db, sand and clay contents (n=190, r2=0.23). Because soil C stock estimates are more sensitive to variation in soil mass and volume determinations than to variation in C concentration, prediction equations such as these may be used on carefully collected samples to constrain soil C stocks. The geo-referenced ISCN database allows users the opportunity to derive similar predictive relationships among measured soil parameters; continued input of new datasets from highly weathered soils of the Americas will improve the precision of these prediction equations.

EFFECTS OF LARVAL STOCKING DENSITY ON LABORATORY-SCALE AND COMMERICAL-SCALE PRODUCTION OF SUMMER FLOUNDER, PARALICHTHYS DENTATUS

EPA Science Inventory

Three experiments investigating larval stocking densities of summer flounder from hatch to metamorphosis, Paralichthys dentatus, were conducted at laboratory-scale (75-L aquaria) and at commercial scale (1,000-L tanks). Experiments 1 and 2 at commercial scale tested the densities...

A stand density management diagram for sawtimber-sized mixed upland central hardwoods

Treesearch

J.A., Jr. Kershaw; B.C. Fischer

1991-01-01

Data from 190 CFI plots located in southern and west-central Indiana are used to develop a stand density diagram for sawtimber-sized mixed upland hardwoods in the Central States. The stand density diagram utilizes the concepts of self-thinning to establish a maximum size-density curve, and the stocking standards of Gingrich (1967) to formulate imtermediate stocking...

Using a Density-Management Diagram to Develop Thinning Schedules for Loblolly Pine Plantations

Treesearch

Thomas J. Dean; V. Clark Baldwin

1993-01-01

A method for developing thinning schedules using a density-management diagram is presented. A density-management diagram is a form of stocking chart based on patterns of natural stand development. The diagram allows rotation diameter and the upper and lower limits of growing stock to be easily transformed into before and after thinning densities. Site height lines on...

Identification of fine scale and landscape scale drivers of urban aboveground carbon stocks using high-resolution modeling and mapping.

PubMed

Mitchell, Matthew G E; Johansen, Kasper; Maron, Martine; McAlpine, Clive A; Wu, Dan; Rhodes, Jonathan R

2018-05-01

Urban areas are sources of land use change and CO 2 emissions that contribute to global climate change. Despite this, assessments of urban vegetation carbon stocks often fail to identify important landscape-scale drivers of variation in urban carbon, especially the potential effects of landscape structure variables at different spatial scales. We combined field measurements with Light Detection And Ranging (LiDAR) data to build high-resolution models of woody plant aboveground carbon across the urban portion of Brisbane, Australia, and then identified landscape scale drivers of these carbon stocks. First, we used LiDAR data to quantify the extent and vertical structure of vegetation across the city at high resolution (5×5m). Next, we paired this data with aboveground carbon measurements at 219 sites to create boosted regression tree models and map aboveground carbon across the city. We then used these maps to determine how spatial variation in land cover/land use and landscape structure affects these carbon stocks. Foliage densities above 5m height, tree canopy height, and the presence of ground openings had the strongest relationships with aboveground carbon. Using these fine-scale relationships, we estimate that 2.2±0.4 TgC are stored aboveground in the urban portion of Brisbane, with mean densities of 32.6±5.8MgCha -1 calculated across the entire urban land area, and 110.9±19.7MgCha -1 calculated within treed areas. Predicted carbon densities within treed areas showed strong positive relationships with the proportion of surrounding tree cover and how clumped that tree cover was at both 1km 2 and 1ha resolutions. Our models predict that even dense urban areas with low tree cover can have high carbon densities at fine scales. We conclude that actions and policies aimed at increasing urban carbon should focus on those areas where urban tree cover is most fragmented. Copyright © 2017 Elsevier B.V. All rights reserved.

Co-assessment of biomass and soil organic carbon stocks in a future reservoir area located in Southeast Asia.

PubMed

Descloux, Stéphane; Chanudet, Vincent; Poilvé, Hervé; Grégoire, Alain

2011-02-01

An assessment of the organic carbon stock present in living or dead vegetation and in the soil on the 450 km2 of the future Nam Theun 2 hydroelectric reservoir in Lao People's Democratic Republic was made. Nine land cover types were defined on the studied area: dense, medium, light, degraded, and riparian forests; agricultural soil; swamps; water; and others (roads, construction sites, and so on). Their geographical distribution was assessed by remote sensing using two 2008 SPOT 5 images. The area is mainly covered by dense and light forests (59%), while agricultural soil and swamps account for 11% and 2%, respectively. For each of these cover types, except water, organic carbon density was measured in the five pools defined by the Intergovernmental Panel on Climate Change: aboveground biomass, litter, deadwood, belowground biomass, and soil organic carbon. The area-weighted mean carbon densities for these pools were estimated at 45.4, 2.0, 2.2, 3.4, and 62.2 tC/ha, respectively, i.e., a total of about 115±15 tC/ha for a soil thickness of 30 cm, corresponding to a total flooded organic carbon stock of 5.1±0.7 MtC. This value is much lower than the carbon density for some South American reservoirs for example where total organic carbon stocks range from 251 to 326 tC/ha. It can be mainly explained by (1) the higher biomass density of South American tropical primary rainforest than of forests in this study and (2) the high proportion of areas with low carbon density, such as agricultural or slash-and-burn zones, in the studied area.

Stocking density effects on production characteristics and body composition of market size cobia, Rachycentron canadum, reared in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Production density in excess of a critical threshold can result in a negative relationship between stocking density and fish production. This study was conducted to evaluate production characteristics of juvenile cobia Rachycentron canadum, reared to market size in production-scale recirculating aq...

Density-independent survival of wild lake trout in the Apostle Islands area of Lake Superior

USGS Publications Warehouse

Bronte, Charles R.; Schram, Stephen T.; Selgeby, James H.; Swanson, Bruce L.

1995-01-01

The lake trout (Salvelinus namaycush) stock at Gull Island Shoal in western Lake Superior was one of only a few stocks of lean lake trout in the Great Lakes that survived overfishing and predation by the sea lamprey (Petromyzon marinus). Since the mid 1960s, the abundance of wild recruits measured at age 0 and the number of age-7 to -11 wild fish recruited to the fishable stock have increased. We used the Varley-Gradwell method to test for density-dependent survival between these life stages. Survival from age-0 to ages 7–11 was not affected by increasing density, which suggests that further increases in recruitment and stock size are still possible. We suggest that testing for the existence of density-dependent survival can be used to indicate when lake trout populations are rehabilitated.

Vermicomposting of source-separated human faeces by Eisenia fetida: effect of stocking density on feed consumption rate, growth characteristics and vermicompost production.

PubMed

Yadav, Kunwar D; Tare, Vinod; Ahammed, M Mansoor

2011-06-01

The main objective of the present study was to determine the optimum stocking density for feed consumption rate, biomass growth and reproduction of earthworm Eisenia fetida as well as determining and characterising vermicompost quantity and product, respectively, during vermicomposting of source-separated human faeces. For this, a number of experiments spanning up to 3 months were conducted using soil and vermicompost as support materials. Stocking density in the range of 0.25-5.00 kg/m(2) was employed in different tests. The results showed that 0.40-0.45 kg-feed/kg-worm/day was the maximum feed consumption rate by E. fetida in human faeces. The optimum stocking densities were 3.00 kg/m(2) for bioconversion of human faeces to vermicompost, and 0.50 kg/m(2) for earthworm biomass growth and reproduction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Causes of declining survival of lake trout stocked in U.S. waters of Lake Superior in 1963-1986

USGS Publications Warehouse

Hansen, Michael J.; Ebener, Mark P.; Schorfhaar, Richard G.; Schram, Stephen T.; Schreiner, Donald R.; Selgeby, James H.; Taylor, William W.

1996-01-01

Survival of the 1963-1982 year-classes of stocked yearling lake trout Salvelinus namaycush declined significantly over time in Lake Superior. To investigate possible causes of this decline, a Ricker model of stock-recruitment was used to describe the catch per effort (CPE) of age-7 stocked lake trout in the Michigan, Minnesota, and Wisconsin waters of Lake Superior as functions of the numbers of yearlings stocked 6 years earlier (an index of density dependence), the density (CPE) of wild adult lake trout (an index of predation), and large-mesh (a?Y 114-mm stretch-measure) gill-net fishing effort (an index of fishing mortality). Declining CPE of stocked lake trout in Michigan and Wisconsin was significantly associated with increasing large-mesh gillnet fishing effort. Declining CPE of stocked lake trout in Minnesota was significantly associated with increasing density of wild lake trout. Declining survival of stocked lake trout may therefore have been caused by increased mortality in large-mesh gill-net fisheries in Michigan and Wisconsin, and by predation by wild lake trout that recently recolonized the Minnesota area. We recommend that experimental management be pursued to determine the relative importance of large-mesh gillnet fishing effort and of predation by wild lake trout on the survival of stocked lake trout in U.S. waters of Lake Superior.

High-resolution mapping of forest carbon stocks in the Colombian Amazon

NASA Astrophysics Data System (ADS)

Asner, G. P.; Clark, J. K.; Mascaro, J.; Galindo García, G. A.; Chadwick, K. D.; Navarrete Encinales, D. A.; Paez-Acosta, G.; Cabrera Montenegro, E.; Kennedy-Bowdoin, T.; Duque, Á.; Balaji, A.; von Hildebrand, P.; Maatoug, L.; Bernal, J. F. Phillips; Yepes Quintero, A. P.; Knapp, D. E.; García Dávila, M. C.; Jacobson, J.; Ordóñez, M. F.

2012-07-01

High-resolution mapping of tropical forest carbon stocks can assist forest management and improve implementation of large-scale carbon retention and enhancement programs. Previous high-resolution approaches have relied on field plot and/or light detection and ranging (LiDAR) samples of aboveground carbon density, which are typically upscaled to larger geographic areas using stratification maps. Such efforts often rely on detailed vegetation maps to stratify the region for sampling, but existing tropical forest maps are often too coarse and field plots too sparse for high-resolution carbon assessments. We developed a top-down approach for high-resolution carbon mapping in a 16.5 million ha region (> 40%) of the Colombian Amazon - a remote landscape seldom documented. We report on three advances for large-scale carbon mapping: (i) employing a universal approach to airborne LiDAR-calibration with limited field data; (ii) quantifying environmental controls over carbon densities; and (iii) developing stratification- and regression-based approaches for scaling up to regions outside of LiDAR coverage. We found that carbon stocks are predicted by a combination of satellite-derived elevation, fractional canopy cover and terrain ruggedness, allowing upscaling of the LiDAR samples to the full 16.5 million ha region. LiDAR-derived carbon maps have 14% uncertainty at 1 ha resolution, and the regional map based on stratification has 28% uncertainty in any given hectare. High-resolution approaches with quantifiable pixel-scale uncertainties will provide the most confidence for monitoring changes in tropical forest carbon stocks. Improved confidence will allow resource managers and decision makers to more rapidly and effectively implement actions that better conserve and utilize forests in tropical regions.

High-resolution Mapping of Forest Carbon Stocks in the Colombian Amazon

NASA Astrophysics Data System (ADS)

Asner, G. P.; Clark, J. K.; Mascaro, J.; Galindo García, G. A.; Chadwick, K. D.; Navarrete Encinales, D. A.; Paez-Acosta, G.; Cabrera Montenegro, E.; Kennedy-Bowdoin, T.; Duque, Á.; Balaji, A.; von Hildebrand, P.; Maatoug, L.; Bernal, J. F. Phillips; Knapp, D. E.; García Dávila, M. C.; Jacobson, J.; Ordóñez, M. F.

2012-03-01

High-resolution mapping of tropical forest carbon stocks can assist forest management and improve implementation of large-scale carbon retention and enhancement programs. Previous high-resolution approaches have relied on field plot and/or Light Detection and Ranging (LiDAR) samples of aboveground carbon density, which are typically upscaled to larger geographic areas using stratification maps. Such efforts often rely on detailed vegetation maps to stratify the region for sampling, but existing tropical forest maps are often too coarse and field plots too sparse for high resolution carbon assessments. We developed a top-down approach for high-resolution carbon mapping in a 16.5 million ha region (>40 %) of the Colombian Amazon - a remote landscape seldom documented. We report on three advances for large-scale carbon mapping: (i) employing a universal approach to airborne LiDAR-calibration with limited field data; (ii) quantifying environmental controls over carbon densities; and (iii) developing stratification- and regression-based approaches for scaling up to regions outside of LiDAR coverage. We found that carbon stocks are predicted by a combination of satellite-derived elevation, fractional canopy cover and terrain ruggedness, allowing upscaling of the LiDAR samples to the full 16.5 million ha region. LiDAR-derived carbon mapping samples had 14.6 % uncertainty at 1 ha resolution, and regional maps based on stratification and regression approaches had 25.6 % and 29.6 % uncertainty, respectively, in any given hectare. High-resolution approaches with reported local-scale uncertainties will provide the most confidence for monitoring changes in tropical forest carbon stocks. Improved confidence will allow resource managers and decision-makers to more rapidly and effectively implement actions that better conserve and utilize forests in tropical regions.

Assessing effects of stocked trout on nongame fish assemblages in southern Appalachian Mountain streams

USGS Publications Warehouse

Weaver, D.; Kwak, Thomas J.

2013-01-01

Fisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before-after, control-impact (BACI) experimental design to detect short-term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long-term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery-reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream management, and conservation of native fishes.

Effect of stocking density on performances of juvenile turbot ( Scophthalmus maximus) in recirculating aquaculture systems

NASA Astrophysics Data System (ADS)

Li, Xian; Liu, Ying; Blancheton, Jean-Paul

2013-05-01

Limited information has been available about the influence of loading density on the performances of Scophthalmus maximus, especially in recirculating aquaculture systems (RAS). In this study, turbot (13.84±2.74 g; average weight±SD) were reared at four different initial densities (low 0.66, medium 1.26, sub-high 2.56, high 4.00 kg/m2) for 10 weeks in RAS at 23±1°C. Final densities were 4.67, 7.25, 14.16, and 17.47 kg/m2, respectively, which translate to 82, 108, 214, and 282 percent coverage of the tank bottom. Density had both negative and independent impacts on growth. The final mean weight, specific growth rate (SGR), and voluntary feed intake significantly decreased and the coefficient of variation (CV) of final body weight increased with increase in stocking density. The medium and sub-high density groups did not differ significantly in SGR, mean weight, CV, food conversion rate (FCR), feed intake, blood parameters, and digestive enzymes. The protease activities of the digestive tract at pH 7, 8.5, 9, and 10 were significantly higher for the highest density group, but tended to be lower (not significantly) at pH 4 and 8.5 for the lowest density group. The intensity of protease activity was inversely related to feed intake at the different densities. Catalase activity was higher (but not significantly) at the highest density, perhaps because high density started to induce an oxidative effect in turbot. In conclusion, turbot can be cultured in RAS at a density of less than 17.47 kg/m2. With good water quality and no feed limitation, initial density between 1.26 and 2.56 kg/m2 (final: 7.25 and 14.16 kg/m2) would not negatively affect the turbot cultured in RAS. For culture at higher density, multi-level feeding devices are suggested to ease feeding competition.

Global carbon stocks and potential emissions due to mangrove deforestation from 2000 to 2012

NASA Astrophysics Data System (ADS)

Hamilton, Stuart E.; Friess, Daniel A.

2018-03-01

Mangrove forests store high densities of organic carbon, which, when coupled with high rates of deforestation, means that mangroves have the potential to contribute substantially to carbon emissions. Consequently, mangroves are strong candidates for inclusion in nationally determined contributions (NDCs) to the United Nations Framework Convention on Climate Change (UNFCCC), and payments for ecosystem services (PES) programmes that financially incentivize the conservation of forested carbon stocks. This study quantifies annual mangrove carbon stocks from 2000 to 2012 at the global, national and sub-national levels, and global carbon emissions resulting from deforestation over the same time period. Globally, mangroves stored 4.19 Pg of carbon in 2012, with Indonesia, Brazil, Malaysia and Papua New Guinea accounting for more than 50% of the global stock. 2.96 Pg of the global carbon stock is contained within the soil and 1.23 Pg in the living biomass. Two percent of global mangrove carbon was lost between 2000 and 2012, equivalent to a maximum potential of 316,996,250 t of CO2 emissions.

Increasing market efficiency in the stock markets

NASA Astrophysics Data System (ADS)

Yang, Jae-Suk; Kwak, Wooseop; Kaizoji, Taisei; Kim, In-Mook

2008-01-01

We study the temporal evolutions of three stock markets; Standard and Poor's 500 index, Nikkei 225 Stock Average, and the Korea Composite Stock Price Index. We observe that the probability density function of the log-return has a fat tail but the tail index has been increasing continuously in recent years. We have also found that the variance of the autocorrelation function, the scaling exponent of the standard deviation, and the statistical complexity decrease, but that the entropy density increases as time goes over time. We introduce a modified microscopic spin model and simulate the model to confirm such increasing and decreasing tendencies in statistical quantities. These findings indicate that these three stock markets are becoming more efficient.

Lake trout (Salvelinus namaycush) populations in Lake Superior and their restoration in 1959-1993

USGS Publications Warehouse

Hansen, Michael J.; Peck, James W.; Schorfhaar, Richard G.; Selgeby, James H.; Schreiner, Donald R.; Schram, Stephen T.; Swanson, Bruce L.; MacCallum, Wayne R.; Burnham-Curtis, Mary K.; Curtis, Gary L.; Heinrich, John W.; Young, Robert J.

1995-01-01

Naturally-reproducing populations of lake trout (Salvelinus namaycush) have been reestablished in most of Lake Superior, but have not been restored to 1929-1943 average abundance. Progress toward lake trout restoration in Lake Superior is described, management actions are reviewed, and the effectiveness of those actions is evaluated; especially stocking lake trout as a tool for building spawning stocks, and subsequently, populations of wild recruits. Widespread destruction of lake trout stocks in the 1950s due to an intense fishery and sea lamprey (Petromyzon marinus) predation resulted in lower overall phenotypic diversity than was previously present. Stocking of yearling lake trout, begun in the 1950s, produced high densities of spawners that reproduced wherever inshore spawning habitat was widespread. Sea lampreys were greatly reduced, beginning in 1961, using selective chemical toxicants and barrier dams, but continue to exert substantial mortality. Fishery regulation was least effective in Wisconsin, where excessive gillnet effort caused high by-catch of lake trout until 1991, and in eastern Michigan, where lake trout restoration was deferred in favor of a tribal fishery for lake whitefish (Coregonus clupeaformis) in 1985. Restoration of stocks was quicker in offshore areas where remnant wild lake trout survived and fishing intensity was low, and was slower in inshore areas where stocked lake trout reproduced successfully and fishing intensity was high. Inshore stocks of wild lake trout are currently about 61 % of historic abundance in Michigan and 53% in Wisconsin. Direct comparison of modern and historic abundances of inshore lake trout stocks in Minnesota and Ontario is impossible due to lack of historic stock assessment data. Stocks in Minnesota are less abundant at present than in Michigan or Wisconsin, and stocks in Ontario are similar to those in Michigan. Further progress in stock recovery can only be achieved if sea lampreys are depressed and if fisheries are constrained further than at present.

Regulation of Oil Biosynthesis in Algae

DTIC Science & Technology

2014-10-06

renewed interest in microalgae as potential feed stock for renewable fuels including high energy density aviation fuels. Microalgae accumulate large...mechanisms of TAG accumulation relevant to other microalgae and perhaps dedicated biofuel crop plants. Knowledge and understanding of algal model systems...energy density liquid fuels. Long Term Objectives. Under permissive conditions, i.e. nutrient deprivation, many microalgae accumulate oils (TAGs

Crown development: an index of stand density

Treesearch

John E. Krajicek; Kenneth A. Brinkman

1957-01-01

A study of crown characteristics of several hundred open-grown oak, hickory, and Norway spruce trees in Iowa revealed a high correlation between stem diameter and crown area. Consideration of this relationship led to the idea that perhaps here was a realistic way to measure and evaluate stand density or stocking. If, given unlimited growing space, trees of a certain...

Stock density managed in real-time

USDA-ARS?s Scientific Manuscript database

The spatio-temporal management of stocking density will be possible once virtual fencing (VF) becomes a commercial reality. VF uses sensory cues (currently audio and electrical stimulation) to change an instrumented animal's forward direction of movement. Free-ranging cattle instrumented with VF e...

Forest biomass carbon stocks and variation in Tibet's carbon-dense forests from 2001 to 2050.

PubMed

Sun, Xiangyang; Wang, Genxu; Huang, Mei; Chang, Ruiying; Ran, Fei

2016-10-05

Tibet's forests, in contrast to China's other forests, are characterized by primary forests, high carbon (C) density and less anthropogenic disturbance, and they function as an important carbon pool in China. Using the biomass C density data from 413 forest inventory sites and a spatial forest age map, we developed an allometric equation for the forest biomass C density and forest age to assess the spatial biomass C stocks and variation in Tibet's forests from 2001 to 2050. The results indicated that the forest biomass C stock would increase from 831.1 Tg C in 2001 to 969.4 Tg C in 2050, with a net C gain of 3.6 Tg C yr -1 between 2001 and 2010 and a decrease of 1.9 Tg C yr -1 between 2040 and 2050. Carbon tends to allocate more in the roots of fir forests and less in the roots of spruce and pine forests with increasing stand age. The increase of the biomass carbon pool does not promote significant augmentation of the soil carbon pool. Our findings suggest that Tibet's mature forests will remain a persistent C sink until 2050. However, afforestation or reforestation, especially with the larger carbon sink potential forest types, such as fir and spruce, should be carried out to maintain the high C sink capacity.

Forest biomass carbon stocks and variation in Tibet’s carbon-dense forests from 2001 to 2050

PubMed Central

Sun, Xiangyang; Wang, Genxu; Huang, Mei; Chang, Ruiying; Ran, Fei

2016-01-01

Tibet’s forests, in contrast to China’s other forests, are characterized by primary forests, high carbon (C) density and less anthropogenic disturbance, and they function as an important carbon pool in China. Using the biomass C density data from 413 forest inventory sites and a spatial forest age map, we developed an allometric equation for the forest biomass C density and forest age to assess the spatial biomass C stocks and variation in Tibet’s forests from 2001 to 2050. The results indicated that the forest biomass C stock would increase from 831.1 Tg C in 2001 to 969.4 Tg C in 2050, with a net C gain of 3.6 Tg C yr−1 between 2001 and 2010 and a decrease of 1.9 Tg C yr−1 between 2040 and 2050. Carbon tends to allocate more in the roots of fir forests and less in the roots of spruce and pine forests with increasing stand age. The increase of the biomass carbon pool does not promote significant augmentation of the soil carbon pool. Our findings suggest that Tibet’s mature forests will remain a persistent C sink until 2050. However, afforestation or reforestation, especially with the larger carbon sink potential forest types, such as fir and spruce, should be carried out to maintain the high C sink capacity. PMID:27703215

Effectiveness of management interventions on forest carbon stock in planted forests in Nepal.

PubMed

Dangal, Shambhu Prasad; Das, Abhoy Kumar; Paudel, Shyam Krishna

2017-07-01

Nepal has successfully established more than 370,000 ha of plantations, mostly with Pinus patula, in the last three and a half decades. However, intensive management of these planted forests is very limited. Despite the fact that the Kyoto Convention in 1997 recognized the role of plantations for forest-carbon sequestration, there is still limited knowledge on the effects of management practices and stand density on carbon-sequestration of popular plantation species (i.e. Pinus patula) in Nepal. We carried out case studies in four community forests planted between 1976 and 1990 to assess the impacts of management on forest carbon stocks. The study found that the average carbon stock in the pine plantations was 217 Mg C ha -1 , and was lower in forests with intensively managed plantations (214.3 Mg C ha -1 ) than in traditionally managed plantations (219 Mg C ha -1 ). However, it was the reverse in case of soil carbon, which was higher (78.65 Mg C ha -1 ) in the forests with intensive management. Though stand density was positively correlated with carbon stock, the proportionate increment in carbon stock was lower with increasing stand density, as carbon stock increased by less than 25% with a doubling of stand density (300-600). The total carbon stock was higher in plantations aged between 25 and 30 years compared to those aged between 30 and 35 years. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tree-centric mapping of forest carbon density from airborne laser scanning and hyperspectral data.

PubMed

Dalponte, Michele; Coomes, David A

2016-10-01

Forests are a major component of the global carbon cycle, and accurate estimation of forest carbon stocks and fluxes is important in the context of anthropogenic global change. Airborne laser scanning (ALS) data sets are increasingly recognized as outstanding data sources for high-fidelity mapping of carbon stocks at regional scales.We develop a tree-centric approach to carbon mapping, based on identifying individual tree crowns (ITCs) and species from airborne remote sensing data, from which individual tree carbon stocks are calculated. We identify ITCs from the laser scanning point cloud using a region-growing algorithm and identifying species from airborne hyperspectral data by machine learning. For each detected tree, we predict stem diameter from its height and crown-width estimate. From that point on, we use well-established approaches developed for field-based inventories: above-ground biomasses of trees are estimated using published allometries and summed within plots to estimate carbon density.We show this approach is highly reliable: tests in the Italian Alps demonstrated a close relationship between field- and ALS-based estimates of carbon stocks ( r 2  = 0·98). Small trees are invisible from the air, and a correction factor is required to accommodate this effect.An advantage of the tree-centric approach over existing area-based methods is that it can produce maps at any scale and is fundamentally based on field-based inventory methods, making it intuitive and transparent. Airborne laser scanning, hyperspectral sensing and computational power are all advancing rapidly, making it increasingly feasible to use ITC approaches for effective mapping of forest carbon density also inside wider carbon mapping programs like REDD++.

Relation of quantity of seed sown and density of seedlings to the development and survival of forest planting stock

Treesearch

W. G. Wahlenberg

1929-01-01

It is obvious that seedlings grown in dense stands can not develop so well as those grown without crowding. Nurserymen naturally wish to avoid injury to their stock from crowding, but they also desire to utilize their soil space as fully as possible. The optimum density of stand for each species and age class of nursery stock can be determined within reasonably close...

Broiler performance, body weight variance, feed and water intake, and carcass quality at different stocking densities.

PubMed

Feddes, J J R; Emmanuel, E J; Zuidhoft, M J

2002-06-01

The effects of four stocking and water nipple densities on broiler performance and carcass traits were measured in two trials. The stocking densities of 23.8, 17.9, 14.3, and 11.9 birds/m2 corresponded to 260, 195, 156, and 130 birds per pen, respectively. The water nipple densities were 5, 10, 15, and 20 birds per water nipple. Birds in Trial 1 were processed at Day 39 and those in Trial 2 were processed at Day 42. Water and feed were provided ad libitum and light was provided 23 h/ d. Water nipple density had no effect on broiler performance or carcass quality. Birds grown at 23.8 birds/m2 had lower BW (1,898 g) and carcass weights (1,334 g), whereas birds grown at 14.3 birds/m2 had the highest BW (1,985 g) and carcass weights (1,432 g). Although the treatment with 23.8 birds/m2 gave the lowest BW, the yield of broilers per unit of floor space was highest (46.0 kg/m2). The coefficient of variation for BW was higher in the treatment with 11.9 birds/m2 (15.3 %) than in the other treatments (13.0%). The birds in the treatment with 11.9 birds/m2 consumed the least feed (2,993 g/bird) and those in the 14.3 birds/m2 treatment consumed the most feed (3,183 g/bird). The amount of water consumed and the water to feed ratio was highest in the 23.8 birds/m2 treatment (5,546 mL/bird and 1.85 mL/g, respectively). Stocking density had no effect on mortality, breast yield, carcass grading, incidence of scratches, or carcass quality. It was concluded high yield per unit area with good carcass quality could be achieved when ventilation rate and air circulation were adequate.

Seedbed Density Affects Size of 3-0 Green Ash Nursery Stock

Treesearch

J.H. Stoeckeler

1967-01-01

Nursery seedbed density of 3-0 green ash, which ranged from 4 to 36 trees per square foot at Carlos Avery Nursery, Forest Lake, Minn., had a marked effect on caliper, height, fresh weight, and percent and amound of plantable stock. The highest number of good-quality trees was produced at a density of 12.5 trees per square foot.

Effects of fish density and river fertilization on algal standing stocks, invertebrates communities, and fish production in an Arctic River

USGS Publications Warehouse

Deegan, Linda A.; Peterson, B.J.; Golden, H.; McIvor, C.C.; Miller, M.C.

1997-01-01

This study examined the relative importance of bottom-up and top-down controls of an arctic stream food web by simultaneous manipulation of the top predator and nutrient availability. We created a two-step trophic system (algae to insects) by removal of the top predator (Arctic grayling, Thymallus arcticus) in fertilized and control stream reaches. Fish abundance was also increased 10 times to examine the effect of high fish density on stream ecosystem dynamics and fish. We measured the response of epilithic algae, benthic and drifting insects, and fish to nutrient enrichment and to changes in fish density. Insect grazers had little effect on algae and fish had little effect on insects. In both the control and fertilized reaches, fish growth, energy storage, and reproductive response of females declined with increased fish density. Fish growth and energy storage were more closely correlated with per capita insect availability than with per capita algal standing stock

Effects of fumonisin B1 and mycotoxin binders on growth performance, tibia characteristics, gut physiology, and stress indicators in broiler chickens raised in different stocking densities.

PubMed

Lee, S; Kim, D-H; Keum, M-C; Han, E; An, B-K; Chang, H-H; Choi, Y-H; Moon, B-H; Lee, K-W

2018-03-01

The present study was carried out to investigate the effects of stocking density, fumonisin B1 (FB), and mycotoxin binder (TB) on growth performance, bone quality, physiological stress indicators, and gut health in broiler chickens. Day-old Ross 308 male broiler chicks (n = 1,440/experiment) were randomly allocated to 72 floor pens in a 3 × 2 × 2 factorial arrangement, using 3 stocking densities (12.5 birds/m2 [HSD], 10 birds/m2 [MSD], or 7.5 birds/m2 [LSD]), 2 levels of purified FB (0 or 10 ppm), and 2 levels of TB (0 or 0.2%). Each treatment had 6 replicates (n = 6/treatment) and experiments lasted 34 days. All data were analyzed using 3-way ANOVA with stocking density level, FB, and TB as main factors. Body weight gain and feed intake were lower (P < 0.05) in broilers kept at HSD and MSD compared to LSD-housed counterparts. Birds fed an FB-contaminated diet exhibited a higher feed-to-gain ratio compared with those fed an FB-free diet (P < 0.05). None of the treatments affected intestinal morphology or ileal secretory immunoglobulin A levels. Stocking density affected tibia breaking strength (P < 0.05), which was lower in chickens housed at HSD compared with LSD-housed chickens. The heterophil/lymphocyte ratio (H/L ratio) was elevated (P < 0.05) in HSD and MSD groups compared with the LSD group. Serum nitric oxide (NO) levels were elevated (P < 0.05) in chickens fed the FB-contaminated diet compared with the control diet-fed counterparts. Significant interaction (P < 0.05) between FB and TB on serum NO levels was noted. In summary, increasing stocking density lowered growth performance and bone quality, but increased the H/L ratio. Dietary TB did not affect FB-induced increases in the feed-to-gain ratio. No interaction was observed between stocking density and FB for the measured variables.

Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

PubMed

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm(-3)) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm(-3)) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1). Higher SOC contents (320 g kg(-1)) were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1)). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth) account for 10.4 kg m(-2), compared to 3.4 kg m(-2) in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

Intercropping with switchgrass improves net greenhouse gas balance in hybrid poplar plantations on a sand soil

USDA-ARS?s Scientific Manuscript database

Highly productive, commercial hybrid poplar plantations are being managed in the Pacific Northwest for high-value timber production at relatively low stocking densities under irrigation. The open understory was used to produce switchgrass (Panicum virgatum) prior to canopy closure. The objectives ...

Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare

PubMed Central

Ruhnke, Isabelle; de Koning, Carolyn; Drake, Kelly; Skerman, Alan G.; Hinch, Geoff N.; Glatz, Philip C.

2017-01-01

Baseline information on demographics and practices on semi-intensive free-range egg farms with an outdoor stocking density of ≤1500 hens/hectare in Australia is presented. Free-range egg production is changing the structure of the egg industry in Australia and a broad variety and tiers of free-range systems have emerged due to lack of concrete legislative standards on outdoor stocking densities in the past. Information was extracted from a pre-existing online free-range poultry survey dataset, consisting of a total of 79 questions related to nutrition, pasture management, welfare and health, animal housing, environmental impact and economics. Forty-one free-range egg farms, with an outdoor stocking density of ≤1500 hens/hectare, were identified in the dataset from all major Australian states. Two types of semi-intensive free-range housing systems were documented: mobile (modified caravan/trailer) housing (56%), and fixed sheds (44%). Seventy-two percent of respondents reported >75% of the hens in the flock used the outdoor range. All respondents reported ingestion of range components by hens in the form of vegetation, insects, stones and grit. Up to 10% mortality was reported by 40% respondents with predation (34%), cannibalism (29%), heat stress (24%) and grass impaction (19.5%) as major causes. Biosecurity on farms was sub-optimal with 8 of the 10 actions implemented by <50% respondents. Customer demand, consumer sentiment and welfare were the major factors for farmers moving into free-range egg production. This study resulted in identification of current practices and key challenges on semi-intensive free-range egg farms. Applied research and communication of results to farmers is highly recommended to ensure optimum health and welfare of free-range laying hens and sustained egg production. PMID:29065169

Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare.

PubMed

Singh, Mini; Ruhnke, Isabelle; de Koning, Carolyn; Drake, Kelly; Skerman, Alan G; Hinch, Geoff N; Glatz, Philip C

2017-01-01

Baseline information on demographics and practices on semi-intensive free-range egg farms with an outdoor stocking density of ≤1500 hens/hectare in Australia is presented. Free-range egg production is changing the structure of the egg industry in Australia and a broad variety and tiers of free-range systems have emerged due to lack of concrete legislative standards on outdoor stocking densities in the past. Information was extracted from a pre-existing online free-range poultry survey dataset, consisting of a total of 79 questions related to nutrition, pasture management, welfare and health, animal housing, environmental impact and economics. Forty-one free-range egg farms, with an outdoor stocking density of ≤1500 hens/hectare, were identified in the dataset from all major Australian states. Two types of semi-intensive free-range housing systems were documented: mobile (modified caravan/trailer) housing (56%), and fixed sheds (44%). Seventy-two percent of respondents reported >75% of the hens in the flock used the outdoor range. All respondents reported ingestion of range components by hens in the form of vegetation, insects, stones and grit. Up to 10% mortality was reported by 40% respondents with predation (34%), cannibalism (29%), heat stress (24%) and grass impaction (19.5%) as major causes. Biosecurity on farms was sub-optimal with 8 of the 10 actions implemented by <50% respondents. Customer demand, consumer sentiment and welfare were the major factors for farmers moving into free-range egg production. This study resulted in identification of current practices and key challenges on semi-intensive free-range egg farms. Applied research and communication of results to farmers is highly recommended to ensure optimum health and welfare of free-range laying hens and sustained egg production.

Outdoor stocking density in free-range laying hens: radio-frequency identification of impacts on range use.

PubMed

Campbell, D L M; Hinch, G N; Dyall, T R; Warin, L; Little, B A; Lee, C

2017-01-01

The number and size of free-range laying hen (Gallus gallus domesticus) production systems are increasing within Australia in response to consumer demand for perceived improvement in hen welfare. However, variation in outdoor stocking density has generated consumer dissatisfaction leading to the development of a national information standard on free-range egg labelling by the Australian Consumer Affairs Ministers. The current Australian Model Code of Practice for Domestic Poultry states a guideline of 1500 hens/ha, but no maximum density is set. Radio-frequency identification (RFID) tracking technology was used to measure daily range usage by individual ISA Brown hens housed in six small flocks (150 hens/flock - 50% of hens tagged), each with access to one of three outdoor stocking density treatments (two replicates per treatment: 2000, 10 000, 20 000 hens/ha), from 22 to 26, 27 to 31 and 32 to 36 weeks of age. There was some variation in range usage across the sampling periods and by weeks 32 to 36 individual hens from the lowest stocking density on average used the range for longer each day (P<0.001), with fewer visits and longer maximum durations per visit (P<0.001). Individual hens within all stocking densities varied in the percentage of days they accessed the range with 2% of tagged hens in each treatment never venturing outdoors and a large proportion that accessed the range daily (2000 hens/ha: 80.5%; 10 000 hens/ha: 66.5%; 20 000 hens/ha: 71.4%). On average, 38% to 48% of hens were seen on the range simultaneously and used all available areas of all ranges. These results of experimental-sized flocks have implications for determining optimal outdoor stocking densities for commercial free-range laying hens but further research would be needed to determine the effects of increased range usage on hen welfare.

Fishing diseased abalone to promote yield and conservation

PubMed Central

Ben-Horin, Tal; Bidegain, Gorka; Lenihan, Hunter S.

2016-01-01

Past theoretical models suggest fishing disease-impacted stocks can reduce parasite transmission, but this is a good management strategy only when the exploitation required to reduce transmission does not overfish the stock. We applied this concept to a red abalone fishery so impacted by an infectious disease (withering syndrome) that stock densities plummeted and managers closed the fishery. In addition to the non-selective fishing strategy considered by past disease-fishing models, we modelled targeting (culling) infected individuals, which is plausible in red abalone because modern diagnostic tools can determine infection without harming landed abalone and the diagnostic cost is minor relative to the catch value. The non-selective abalone fishing required to eradicate parasites exceeded thresholds for abalone sustainability, but targeting infected abalone allowed the fishery to generate yield and reduce parasite prevalence while maintaining stock densities at or above the densities attainable if the population was closed to fishing. The effect was strong enough that stock and yield increased even when the catch was one-third uninfected abalone. These results could apply to other fisheries as the diagnostic costs decline relative to catch value. PMID:26880843

Fishing diseased abalone to promote yield and conservation.

PubMed

Ben-Horin, Tal; Lafferty, Kevin D; Bidegain, Gorka; Lenihan, Hunter S

2016-03-05

Past theoretical models suggest fishing disease-impacted stocks can reduce parasite transmission, but this is a good management strategy only when the exploitation required to reduce transmission does not overfish the stock. We applied this concept to a red abalone fishery so impacted by an infectious disease (withering syndrome) that stock densities plummeted and managers closed the fishery. In addition to the non-selective fishing strategy considered by past disease-fishing models, we modelled targeting (culling) infected individuals, which is plausible in red abalone because modern diagnostic tools can determine infection without harming landed abalone and the diagnostic cost is minor relative to the catch value. The non-selective abalone fishing required to eradicate parasites exceeded thresholds for abalone sustainability, but targeting infected abalone allowed the fishery to generate yield and reduce parasite prevalence while maintaining stock densities at or above the densities attainable if the population was closed to fishing. The effect was strong enough that stock and yield increased even when the catch was one-third uninfected abalone. These results could apply to other fisheries as the diagnostic costs decline relative to catch value. © 2016 The Author(s).

Fishing diseased abalone to promote yield and conservation

USGS Publications Warehouse

Ben-Horin, Tal; Lafferty, Kevin D.; Bidegain, Gorka; Lenihan, Hunter S.

2016-01-01

Past theoretical models suggest fishing disease-impacted stocks can reduce parasite transmission, but this is a good management strategy only when the exploitation required to reduce transmission does not overfish the stock. We applied this concept to a red abalone fishery so impacted by an infectious disease (withering syndrome) that stock densities plummeted and managers closed the fishery. In addition to the non-selective fishing strategy considered by past disease-fishing models, we modelled targeting (culling) infected individuals, which is plausible in red abalone because modern diagnostic tools can determine infection without harming landed abalone and the diagnostic cost is minor relative to the catch value. The non-selective abalone fishing required to eradicate parasites exceeded thresholds for abalone sustainability, but targeting infected abalone allowed the fishery to generate yield and reduce parasite prevalence while maintaining stock densities at or above the densities attainable if the population was closed to fishing. The effect was strong enough that stock and yield increased even when the catch was one-third uninfected abalone. These results could apply to other fisheries as the diagnostic costs decline relative to catch value.

Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens housed in enriched colony cages at different stocking densities.

PubMed

Gast, Richard K; Guraya, Rupa; Jones, Deana R; Anderson, Kenneth E; Karcher, Darrin M

2016-06-01

Epidemiologic analyses have linked the frequency of human infections with Salmonella enterica subspecies enterica serovar Enteritidis to the consumption of contaminated eggs and thus to the prevalence of this pathogen in commercial egg-laying flocks. Contamination of the edible contents of eggs by Salmonella Enteritidis is a consequence of the colonization of reproductive tissues in systemically infected hens. The animal welfare implications of laying hen housing systems have been widely debated, but no definitive consensus has yet emerged about the food safety significance of poultry housing options. The present study sought to determine the effects of two different bird stocking densities on the invasion of internal organs by Salmonella Enteritidis in groups of experimentally infected laying hens housed in colony cages enriched with perching and nesting areas. In two trials, groups of laying hens were distributed at two different stocking densities into colony cages and (along with a group housed in conventional cages) orally inoculated with doses of 1.0 × 10(7) cfu of Salmonella Enteritidis. At 5 to 6 d post-inoculation, hens were euthanized and samples of internal organs were removed for bacteriologic culturing. For both trials combined, Salmonella Enteritidis was recovered at a significantly (P < 0.05) greater frequency from hens in enriched colony cages at the higher stocking density than at the lower density from livers (75.0% vs. 51.4%) and ovaries (51.4% vs. 30.6%). However, spleens from hens in enriched colony cages at the higher stocking density were significantly less often positive for Salmonella Enteritidis than from hens in conventional cages at that same density (90.3% vs. 68.1%). These results suggest that stocking density can influence the susceptibility of hens to Salmonella Enteritidis, but other housing systems parameters may also contribute to the outcome of infections. Published by Oxford University Press on behalf of Poultry Science Association 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes

PubMed Central

Eikeset, Anne Maria; Dunlop, Erin S.; Heino, Mikko; Storvik, Geir; Stenseth, Nils C.; Dieckmann, Ulf

2016-01-01

The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world’s largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock’s feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population’s age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock’s historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide. PMID:27940913

Egg production and egg quality in free-range laying hens housed at different outdoor stocking densities.

PubMed

Campbell, D L M; Lee, C; Hinch, G N; Roberts, J R

2017-09-01

Free-range laying hen systems are increasing in number within Australia. Variation in outdoor stocking densities has led to development of a national information standard on free-range egg labeling, including setting a maximum density of 10,000 hens per hectare. However, there are few data on the impacts of differing outdoor densities on production and egg quality. ISA Brown hens in small (150 hens) flocks were housed in identical indoor pens, each with access (from 21 weeks) to different sized ranges simulating one of three outdoor stocking densities (2 replicates each: 2,000 hens/hectare (ha), 10,000 hens/ha, 20,000 hens/ha). Hen-day production was tracked from 21 through 35 weeks with eggs visually graded daily for external deformities. All eggs laid on one day were weighed each week. Eggs were collected from each pen at 25, 30, and 36 weeks and analyzed for egg quality. There were no effects of outdoor stocking density on average hen-day percentage production (P = 0.67), egg weight (P = 0.09), percentages of deformed eggs (P = 0.30), shell reflectivity (P = 0.74), shell breaking strength (P = 0.07), shell deformation (P = 0.83), or shell thickness (P = 0.24). Eggs from hens in the highest density had the highest percentage shell weight (P = 0.004) and eggs from the lowest density had the highest yolk color score (P < 0.001). The amount of cuticle present did not differ between densities (P = 0.95) but some aspects of shell colors (P ≤ 0.01) and location of protoporphyrin IX (P = 0.046) varied. Hen age affected the majority of measurements. Stocking density differences may be related to hen diet as previous radio-frequency identification tracking of individual hens in these flocks showed birds used the range for longer in the lowest density and the least in the highest density, including depleting the range of vegetation sooner in the smaller ranges. An additional study assessing the relationship between individual hen range use, nutrition, and egg quality is warranted. © 2017 Poultry Science Association Inc.

Parapenaeus longirostris (Lucas, 1846) an early warning indicator species of global warming in the central Mediterranean Sea

NASA Astrophysics Data System (ADS)

Colloca, Francesco; Mastrantonio, Gianluca; Lasinio, Giovanna Jona; Ligas, Alessandro; Sartor, Paolo

2014-10-01

The effect of temperature increase on the stock of the deep-sea pink shrimp (Parapenaeus longirostris) was analysed along the western coasts of Italy (North Tyrrhenian-Ligurian Sea: Geographical Sub-Area 9). This crustacean is currently one of the most important commercial species of the trawl fisheries in the Mediterranean Sea. Landings of the species in the North Tyrrhenian-Ligurian Sea have grown consistently during the last years following a rapid increase in the stock size. Since the deep-sea pink shrimp stock is exploited on the same fishing ground of other heavily overexploited stocks in a full mixed and poorly selective fishery, its condition seems to be largely independent of the current fishing exploitation pattern suggesting a positive role of climate change on the dynamic of the stock. To test this hypothesis we investigated the effect of sea surface temperature (SST) on density and distribution of P. longirostris by means of general additive models (GAMs). Two different models were developed for the whole stock and for the recruits (CL < 20 mm) using time series of MEDITS (International bottom trawl survey in the Mediterranean) survey density indices (n km- 2) covering the period 1995-2010. Predictors included were geographical coordinates, quarterly averaged minimum SST, sampling depth and year. Spawners density was included as predictor into the GAM for recruits. The best GAM for the whole stock explained 67.1% of the total deviance, showing a clear increase in density in concomitance with the expansion of the stock northward. We found a significant positive effect of the min SST of all seasons, as expected considering that P. longirostris spawn all year round, with the highest influence played by summer min SST, either in the same or previous year. The best model for recruits explained 64.9% of the total deviance. Recruitment increased linearly with the density of spawners showing a positive temporal trend and an expansion northward. The observed trend in recruitment appeared significantly linked to minimum SST in summer and during the autumn of the previous year, with a positive effect on shrimp density over 23.5 °C and 14 °C respectively. The climate-related changes in recruitment appeared to be the key process driving the dynamics of the stock, involving either higher production or survival in the planktonic stages, or owing to changes in the quality/quantity of nursery habitats.

Frequency and Duration of Fecal Shedding of Salmonella Enteritidis by Experimentally Infected Laying Hens Housed in Enriched Colony Cages at Different Stocking Densities

PubMed Central

Gast, Richard K.; Guraya, Rupa; Jones, Deana R.; Anderson, Kenneth E.; Karcher, Darrin M.

2017-01-01

Human infections with Salmonella Enteritidis are often attributed to the consumption of contaminated eggs, so the prevalence of this pathogen in egg-laying poultry is an important public health risk factor. Numerous and complex environmental influences on Salmonella persistence and transmission are exerted by management practices and housing facilities used in commercial egg production. In recent years, the animal welfare implications of poultry housing systems have guided the development of alternatives to traditional cage-based housing, but their food safety consequences are not yet fully understood. The present study assessed the effects of different bird stocking densities on the frequency and duration of fecal shedding of S. Enteritidis in groups of experimentally infected laying hens housed in colony cages enriched with perching and nesting areas. In two trials, groups of laying hens were distributed at two stocking densities (648 and 973 cm2/bird) into enriched colony cages and (along with a group housed in conventional cages at 648 cm2/bird) orally inoculated with doses of 1.0 × 108 cfu of S. Enteritidis. At 10 weekly postinoculation intervals, samples of voided feces were collected from beneath each cage and cultured to detect S. Enteritidis. Fecal shedding of S. Enteritidis was detected for up to 10 weeks postinoculation by hens in all three housing treatment groups. The overall frequency of positive fecal cultures was significantly (P < 0.05) greater from conventional cages than from enriched colony cages (at the lower stocking density) for the total of all sampling dates (45.0 vs. 33.3%) and also for samples collected at 4–9 weeks postinfection. Likewise, the frequency of S. Enteritidis isolation from feces from conventional cages was significantly greater than from enriched colony cages (at the higher hen stocking density) for the sum of all samples (45.0 vs. 36.7%) and at 6 weeks postinoculation. Moreover, the frequency of S. Enteritidis fecal recovery from enriched colony cages at the higher hen stocking was significantly greater than from similar cages at the lower stocking density for all 10 sampling dates combined (39.4 vs. 33.3%). These results suggest that stocking density can affect S. Enteritidis intestinal colonization and fecal shedding in laying hens, but some other difference between conventional and enriched colony cage systems appears to exert an additional influence. PMID:28443289

The high order dispersion analysis based on first-passage-time probability in financial markets

NASA Astrophysics Data System (ADS)

Liu, Chenggong; Shang, Pengjian; Feng, Guochen

2017-04-01

The study of first-passage-time (FPT) event about financial time series has gained broad research recently, which can provide reference for risk management and investment. In this paper, a new measurement-high order dispersion (HOD)-is developed based on FPT probability to explore financial time series. The tick-by-tick data of three Chinese stock markets and three American stock markets are investigated. We classify the financial markets successfully through analyzing the scaling properties of FPT probabilities of six stock markets and employing HOD method to compare the differences of FPT decay curves. It can be concluded that long-range correlation, fat-tailed broad probability density function and its coupling with nonlinearity mainly lead to the multifractality of financial time series by applying HOD method. Furthermore, we take the fluctuation function of multifractal detrended fluctuation analysis (MF-DFA) to distinguish markets and get consistent results with HOD method, whereas the HOD method is capable of fractionizing the stock markets effectively in the same region. We convince that such explorations are relevant for a better understanding of the financial market mechanisms.

Avian and amphibian use of fenced and unfenced stock ponds in northeastern Oregon forests.

Treesearch

Evelyn L. Bull; Jerry W. Deal; Janet E. Hohmann

2001-01-01

The abundance of birds and amphibian larvae was compared between fenced and unfenced stock ponds in 1993 to determine if fencing improved the habitat for these species in northeastern Oregon. Stock ponds that were fenced had significantly higher densities of bird species, guilds, and taxonomic groups than stock ponds that were unfenced. No differences in the relative...

Stochastic GARCH dynamics describing correlations between stocks

NASA Astrophysics Data System (ADS)

Prat-Ortega, G.; Savel'ev, S. E.

2014-09-01

The ARCH and GARCH processes have been successfully used for modelling price dynamics such as stock returns or foreign exchange rates. Analysing the long range correlations between stocks, we propose a model, based on the GARCH process, which is able to describe the main characteristics of the stock price correlations, including the mean, variance, probability density distribution and the noise spectrum.

The stage-classified matrix models project a significant increase in biomass carbon stocks in China’s forests between 2005 and 2050

PubMed Central

Hu, Huifeng; Wang, Shaopeng; Guo, Zhaodi; Xu, Bing; Fang, Jingyun

2015-01-01

China’s forests are characterized by young age, low carbon (C) density and a large plantation area, implying a high potential for increasing C sinks in the future. Using data of provincial forest area and biomass C density from China’s forest inventories between 1994 and 2008 and the planned forest coverage of the country by 2050, we developed a stage-classified matrix model to predict biomass C stocks of China’s forests from 2005 to 2050. The results showed that total forest biomass C stock would increase from 6.43 Pg C (1 Pg = 1015 g) in 2005 to 9.97 Pg C (95% confidence interval: 8.98 ~ 11.07 Pg C) in 2050, with an overall net C gain of 78.8 Tg C yr−1 (56.7 ~ 103.3 Tg C yr−1; 1 Tg = 1012 g). Our findings suggest that China’s forests will be a large and persistent biomass C sink through 2050. PMID:26110831

The stage-classified matrix models project a significant increase in biomass carbon stocks in China's forests between 2005 and 2050.

PubMed

Hu, Huifeng; Wang, Shaopeng; Guo, Zhaodi; Xu, Bing; Fang, Jingyun

2015-06-25

China's forests are characterized by young age, low carbon (C) density and a large plantation area, implying a high potential for increasing C sinks in the future. Using data of provincial forest area and biomass C density from China's forest inventories between 1994 and 2008 and the planned forest coverage of the country by 2050, we developed a stage-classified matrix model to predict biomass C stocks of China's forests from 2005 to 2050. The results showed that total forest biomass C stock would increase from 6.43 Pg C (1 Pg = 10(15) g) in 2005 to 9.97 Pg C (95% confidence interval: 8.98 ~ 11.07 Pg C) in 2050, with an overall net C gain of 78.8 Tg C yr(-1) (56.7 ~ 103.3 Tg C yr(-1); 1 Tg = 10(12) g). Our findings suggest that China's forests will be a large and persistent biomass C sink through 2050.

Impacts of feedlot floor condition, deposition frequency, and inhibitors on N2O and CH4 emissions from feedlot dung and urine patches.

PubMed

Liao, Wenhua; Liu, Chunjing; Gao, Zhiling

2018-04-09

Patches of dung and urine are major contributors to the feedlot gas emissions. This study investigated the impacts of dung deposition frequency (partly reflecting animal stocking density of a feedlot), dairy feedlot floor conditions (old floor indicated with the presence of consolidated manure pad [CMP] vs. new floor with the absence of consolidated manure pad [CMPn]), and application of dicyandiamide (DCD) and hydroquinone (HQ) on nitrous oxide (N 2 O) and methane (CH 4 ) emissions from patches in the laboratory, and the integrative impacts were expressed in terms of global warming potential (CO 2 -equivalent). Dung deposition frequency, feedlot floor condition, and application of inhibitors showed inverse impacts on N 2 O and CH 4 emissions from patches. Greenhouse gas (GHG) emissions from the dung, urine, and dung+urine patches on the CMP feedlot surface were approximately 7.48, 87.35, and 7.10 times those on the CMPn feedlot surface (P < 0.05). Meanwhile, GHG emissions from CMP and CMPn feedlot surfaces under high deposition frequency condition were approximately 10 and 1.7 times those under low-frequency condition. Moreover, application of HQ slightly reduced the GHG emission from urine patches, by 14.9% (P > 0.05), while applying DCD or DCD+HQ significantly reduced the GHG, by 60.3% and 65.0%, respectively (P < 0.05). Overall, it is necessary to include feedlot management such as animal stocking density and feedlot floor condition to the process of determining emission factors for feedlots. In the future, field measurements to quantitatively evaluate the relative contribution of nitrification and denitrification to the N 2 O emissions of feedlot surfaces are highly required for effective N 2 O control. This study shows that feedlot CH 4 and N 2 O emissions inversely respond to the dicyandiamide (DCD) application. Applying DCD significantly reduces GHG emissions of feedlot urine patches. Feedlot floor condition and stocking density strongly impact feedlot GHG emissions. Including feedlot floor condition and stocking density in the feedlot EF determining process is necessary.

Digital Mapping of Soil Organic Carbon Contents and Stocks in Denmark

PubMed Central

Adhikari, Kabindra; Hartemink, Alfred E.; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B.; Greve, Mogens H.

2014-01-01

Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0−5, 5−15, 15−30, 30−60 and 60−100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg−1 was reported for 0−5 cm soil, whereas there was on average 2.2 g SOC kg−1 at 60−100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg−1 was found at 60−100 cm soil depth. Average SOC stock for 0−30 cm was 72 t ha−1 and in the top 1 m there was 120 t SOC ha−1. In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories. PMID:25137066

Digital mapping of soil organic carbon contents and stocks in Denmark.

PubMed

Adhikari, Kabindra; Hartemink, Alfred E; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B; Greve, Mogens H

2014-01-01

Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories.

The Effect of Season and Stock Density on Blue Oak Establishment

Treesearch

Lillian M. Hall; Melvin R. George; Theodore E. Adams; Peter B. Sands; Douglas D. McCreary

1991-01-01

Cattle have been faulted as a possible cause for poor oak regeneration in California's hardwood rangelands. This study sought to determine the effects of stock density and season of grazing on blue oak (Quercus douglasii) establishment. Year old blue oak seedlings were transplanted into annual grass/rose clover pastures at the Sierra Foothill...

A cost-efficient method to assess carbon stocks in tropical peat soil

NASA Astrophysics Data System (ADS)

Warren, M. W.; Kauffman, J. B.; Murdiyarso, D.; Anshari, G.; Hergoualc'h, K.; Kurnianto, S.; Purbopuspito, J.; Gusmayanti, E.; Afifudin, M.; Rahajoe, J.; Alhamd, L.; Limin, S.; Iswandi, A.

2012-11-01

Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m-3; Cd) as a function of bulk density (gC cm-3; Bd), which can be used to rapidly estimate belowground carbon storage using Bd measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (Cd = Bd × 495.14 + 5.41, R2 = 0.93, n = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm-3, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation Cd = Bd × 468.76 + 5.82, with R2 = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease Cd estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%.

The influences of delay time on the stability of a market model with stochastic volatility

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Mei, Dong-Cheng

2013-02-01

The effects of the delay time on the stability of a market model are investigated, by using a modified Heston model with a cubic nonlinearity and cross-correlated noise sources. These results indicate that: (i) There is an optimal delay time τo which maximally enhances the stability of the stock price under strong demand elasticity of stock price, and maximally reduces the stability of the stock price under weak demand elasticity of stock price; (ii) The cross correlation coefficient of noises and the delay time play an opposite role on the stability for the case of the delay time <τo and the same role for the case of the delay time >τo. Moreover, the probability density function of the escape time of stock price returns, the probability density function of the returns and the correlation function of the returns are compared with other literatures.

The Effects of Prenatal Stocking Densities on the Fear Responses and Sociality of Goat (Capra hircus) Kids

PubMed Central

Chojnacki, Rachel M.; Vas, Judit; Andersen, Inger Lise

2014-01-01

Prenatal stress (stress experienced by a pregnant mother) and its effects on offspring have been comprehensively studied but relatively little research has been done on how prenatal social stress affects farm animals such as goats. Here, we use the operational description of ‘stress’ as “physical or perceived threats to homeostasis.” The aim of this study was to investigate the prenatal effects of different herd densities on the fear responses and sociality of goat kids. Pregnant Norwegian dairy goats were exposed to high, medium or low prenatal animal density treatments throughout gestation (1.0, 2.0 or 3.0 m2 per animal, respectively). One kid per litter was subjected to two behavioral tests at 5 weeks of age. The ‘social test’ was applied to assess the fear responses, sociality and social recognition skills when presented with a familiar and unfamiliar kid and the ‘separation test’ assessed the behavioral coping skills when isolated. The results indicate goat kids from the highest prenatal density of 1.0 m2 were more fearful than the kids from the lower prenatal densities (i.e. made more escape attempts (separation test: P < 0.001) and vocalizations (social test: P < 0.001; separation test: P < 0.001). This effect was more pronounced in females than males in the high density (vocalizations; social test: P < 0.001; separation test: P  =  0.001) and females were generally more social than males. However, goat kids did not differentiate between a familiar and an unfamiliar kid at 5 weeks of age and sociality was not affected by the prenatal density treatment. We conclude that high animal densities during pregnancy in goats produce offspring that have a higher level of fear, particularly in females. Behavioral changes in offspring that occur as an effect of prenatal stress are of high importance as many of the females are recruited to the breeding stock of dairy goats. PMID:24710177

Cyclic development of igneous features and their relationship to high-temperature hydrothermal features in the Henderson porphyry molybdenum deposit, Colorado

USGS Publications Warehouse

Carten, R.B.; Geraghty, E.P.; Walker, B.M.

1988-01-01

The Henderson porphyry molybdenum deposit was formed by the superposition of coupled alteration and mineralization events, of varying intensity and size, that were associated with each of at least 11 intrusions. Deposition of molybdenite was accompanied by time-equivalent silicic and potassic alteration. High-temperature alteration and mineralization are spatially and temporally linked to the crystallization of compositionally zoned magma in the apex of stocks. Differences in hydrothermal features associated with each intrusion (e.g., mass of ore, orientation and type of veins, density of veins, and intensity of alteration) correlate with differences in primary igneous features (e.g., composition, texture, morphology, and size). The systematic relations between hydrothermal and magmatic features suggest that primary magma compositions, including volatile contents, largely control the geometry, volume, level of emplacement, and mechanisms of crystallization of stocks. These elements in turn govern the orientations and densities of fractures, which ultimately determine the distribution patterns of hydrothermal alteration and mineralization. -from Authors

Re-evaluation of forest biomass carbon stocks and lessons from the world's most carbon-dense forests.

PubMed

Keith, Heather; Mackey, Brendan G; Lindenmayer, David B

2009-07-14

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized.

Re-evaluation of forest biomass carbon stocks and lessons from the world's most carbon-dense forests

PubMed Central

Keith, Heather; Mackey, Brendan G.; Lindenmayer, David B.

2009-01-01

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized. PMID:19553199

A stocking diagram for midwestern eastern cotonwood-silver maple-American sycamore bottomland forests

Treesearch

David R. Larsen; Daniel C. Dey; Thomas. Faust

2010-01-01

A stocking diagram for Midwestern bottomland eastern cottonwood (Populus deltoides Bartram ex Marsh.)-silver maple (Acer saccharinum L.)-American sycamore (Platanus occidentalis L.) forests was developed following the methods of S.F. Gingrich (1967. Measuring and evaluating stocking and stand density in upland...

Informing Species Conservation at Multiple Scales Using Data Collected for Marine Mammal Stock Assessments

PubMed Central

Grech, Alana; Sheppard, James; Marsh, Helene

2011-01-01

Background Conservation planning and the design of marine protected areas (MPAs) requires spatially explicit information on the distribution of ecological features. Most species of marine mammals range over large areas and across multiple planning regions. The spatial distributions of marine mammals are difficult to predict using habitat modelling at ecological scales because of insufficient understanding of their habitat needs, however, relevant information may be available from surveys conducted to inform mandatory stock assessments. Methodology and Results We use a 20-year time series of systematic aerial surveys of dugong (Dugong dugong) abundance to create spatially-explicit models of dugong distribution and relative density at the scale of the coastal waters of northeast Australia (∼136,000 km2). We interpolated the corrected data at the scale of 2 km * 2 km planning units using geostatistics. Planning units were classified as low, medium, high and very high dugong density on the basis of the relative density of dugongs estimated from the models and a frequency analysis. Torres Strait was identified as the most significant dugong habitat in northeast Australia and the most globally significant habitat known for any member of the Order Sirenia. The models are used by local, State and Federal agencies to inform management decisions related to the Indigenous harvest of dugongs, gill-net fisheries and Australia's National Representative System of Marine Protected Areas. Conclusion/Significance In this paper we demonstrate that spatially-explicit population models add value to data collected for stock assessments, provide a robust alternative to predictive habitat distribution models, and inform species conservation at multiple scales. PMID:21464933

Soil Organic Carbon Pools and Stocks in Permafrost-Affected Soils on the Tibetan Plateau

PubMed Central

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm−3) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm−3) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg−1. Higher SOC contents (320 g kg−1) were found in OPOM while MOM had the lowest SOC contents (29 g kg−1). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0–30 cm depth) account for 10.4 kg m−2, compared to 3.4 kg m−2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation. PMID:23468904

Consumption dynamics of the adult piscivorous fish community in Spirit Lake, Iowa

USGS Publications Warehouse

Liao, H.; Pierce, C.L.; Larscheid, J.G.

2004-01-01

At Spirit Lake, one of Iowa's most important fisheries, walleye Sander vitreus (formerly Stizostedion vitreum) is one of the most popular species with anglers. Despite a century of walleye stocking and management in Spirit Lake, walleye growth rate, size structure, and angler harvest continue to decline. Our purpose was to determine the magnitude and dynamics of walleye population consumption relative to those of other piscivorous species in Spirit Lake, which would allow managers to judge the feasibility of increasing the abundance, growth rate, and size structure of the walleye population. We quantified food consumption by the adult piscivorous fish community in Spirit Lake over a 3-year period. Data on population dynamics, diet, energy density, and water temperature from 1995 to 1997 were used in bioenergetics models to estimate total consumption by walleye, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieu, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus, and northern pike Esox lucius. Estimated annual consumption by the piscivorous community varied roughly fourfold, ranging from 154,752 kg in 1995 to 662,776 kg in 1997. Walleyes dominated total consumption, accounting for 68, 73, and 90% (1995-1997, respectively) of total food consumption. Walleyes were also the dominant consumers of fish, accounting for 76, 86, and 97% of piscivorous consumption; yellow perch followed, accounting for 16% of piscivorous consumption in 1995 and 12% in 1996. Yellow perch were the predominant fish prey species in all 3 years, accounting for 68, 52, and 36% of the total prey consumed. Natural reproduction is weak, so high walleye densities are maintained by intensive stocking. Walleye stocking drives piscivorous consumption in Spirit Lake, and yearly variation in the cannibalism of stocked walleye fry may be an important determinant of walleye year-class strength and angler success. Reducing walleye stocking intensity, varying stocking intensity from year to year, and attempting to match stocking intensity with the abundance of prey species other than walleye may improve the walleye fishery in Spirit Lake.

Relative abundance, site fidelity, and survival of adult lake trout in Lake Michigan from 1999 to 2001: Implications for future restoration strategies

USGS Publications Warehouse

Bronte, C.R.; Holey, M.E.; Madenjian, C.P.; Jonas, J.L.; Claramunt, R.M.; McKee, P.C.; Toneys, M.L.; Ebener, M.P.; Breidert, B.; Fleischer, G.W.; Hess, R.; Martell, A.W.; Olsen, E.J.

2007-01-01

We compared the relative abundance of lake trout Salvelinus namaycush spawners in gill nets during fall 1999–2001 in Lake Michigan at 19 stocked spawning sites with that at 25 unstocked sites to evaluate how effective site-specific stocking was in recolonizing historically important spawning reefs. The abundance of adult fish was higher at stocked onshore and offshore sites than at unstocked sites. This suggests that site-specific stocking is more effective at establishing spawning aggregations than relying on the ability of hatchery-reared lake trout to find spawning reefs, especially those offshore. Spawner densities were generally too low and too young at most sites to expect significant natural reproduction. However, densities were sufficiently high at some sites for reproduction to occur and therefore the lack of recruitment was attributable to other factors. Less than 3% of all spawners could have been wild fish, which indicates that little natural reproduction occurred in past years. Wounding by sea lamprey Petromyzon marinus was generally lower for Seneca Lake strain fish and highest for strains from Lake Superior. Fish captured at offshore sites in southern Lake Michigan had the lowest probability of wounding, while fish at onshore sites in northern Lake Michigan had the highest probability. The relative survival of the Seneca Lake strain was higher than that of the Lewis Lake or the Marquette strains for the older year-classes examined. Survival differences among strains were less evident for younger year-classes. Recaptures of coded-wire-tagged fish of five strains indicated that most fish returned to their stocking site or to a nearby site and that dispersal from stocking sites during spawning was about 100 km. Restoration strategies should rely on site-specific stocking of lake trout strains with good survival at selected historically important offshore spawning sites to increase egg deposition and the probability of natural reproduction in Lake Michigan.

Effects of genetics, management intensity, and seedling density on early stocking in loblolly pine

Treesearch

Scott D. Roberts; Randall J. Rousseau; B. Landis Herrin

2015-01-01

Rapid establishment and early tree growth can be key factors in successful plantation management. This generally entails planting good quality planting stock at a seedling density appropriate for the management objectives and then managing at an appropriate intensity with a goal of fully occupying the site as quickly as possible within the context of those objectives....

Effects of straw processing and pen stocking density on holstein dairy heifers: ii) behavior and hygiene

USDA-ARS?s Scientific Manuscript database

The effects of pen-stocking density and straw processing on the daily behavior traits and hygiene of Holstein dairy heifers housed in a freestall system are not understood. Our objective was to evaluate these factors in a trial with a 2 × 3 factorial arrangement of straw-processing (GOOD or POOR) an...

Use of black carp (Mylopharyngodon piceus) in biological control of intermediate host snails of fish-borne zoonotic trematodes in nursery ponds in the Red River Delta, Vietnam

PubMed Central

2013-01-01

Background The risks of fish-borne zoonotic trematodes (FZT) to human health constitute an important problem in Vietnam. The infection of humans with these trematodes, such as small liver trematodes (Clonorchis sinensis and Opisthorchis viverrini), intestinal trematodes (Heterophyidae) and others is often thought to be linked to fish culture in areas where the habit of eating raw fish is common. Juvenile fish produced in nurseries are often heavily infected with FZT and since fishes are sold to aquaculture facilities for growth, control of FZT in these fishes should be given priority. Controlling the first intermediate host (i.e., freshwater gastropods), would be an attractive approach, if feasible. The black carp, Mylopharyngodon piceus, is a well-known predator of freshwater snails and is already used successfully for biological control of snails in various parts of the world including Vietnam. Here we report the first trials using it for biological control of intermediate host snails in nursery ponds stocked with 1-week old fry (10–12 mm in length) of Indian carp, Labeo rohita. Methods Semi-field and field experiments were set up to test the effect of black carp on snail populations. In the semi-field experiment a known quantity of snails was initially introduced into a pond which was subsequently stocked with black carp. In the field trial in nursery ponds, density of snails was estimated prior to a nursing cycle and at the end of the cycle (after 9 weeks). Results The results showed that black carp affect the density of snail populations in both semi-field and field conditions. The standing crop of snails in nursery ponds, however, was too high for 2 specimens to greatly reduce snail density within the relatively short nursing cycle. Conclusions We conclude that the black carp can be used in nursery ponds in Northern Vietnam for snail control. Juvenile black carp weighing 100 - 200g should be used because this size primarily prey on intermediate hosts of FZT and other studies have shown that it does not prey on fish fry of other species. It may be necessary to use a high stocking density of black carp or to reduce snail density in the nursery ponds using other measures (e.g. mud removal) prior to stocking fry in order for the black carp to keep the density of intermediate host snails at a very low level. PMID:23680382

Landscape patterns and soil organic carbon stocks in agricultural bocage landscapes

NASA Astrophysics Data System (ADS)

Viaud, Valérie; Lacoste, Marine; Michot, Didier; Walter, Christian

2014-05-01

Soil organic carbon (SOC) has a crucial impact on global carbon storage at world scale. SOC spatial variability is controlled by the landscape patterns resulting from the continuous interactions between the physical environment and the society. Natural and anthropogenic processes occurring and interplaying at the landscape scale, such as soil redistribution in the lateral and vertical dimensions by tillage and water erosion processes or spatial differentiation of land-use and land-management practices, strongly affect SOC dynamics. Inventories of SOC stocks, reflecting their spatial distribution, are thus key elements to develop relevant management strategies to improving carbon sequestration and mitigating climate change and soil degradation. This study aims to quantify SOC stocks and their spatial distribution in a 1,000-ha agricultural bocage landscape with dairy production as dominant farming system (Zone Atelier Armorique, LTER Europe, NW France). The site is characterized by high heterogeneity on short distance due to a high diversity of soils with varying waterlogging, soil parent material, topography, land-use and hedgerow density. SOC content and stocks were measured up to 105-cm depth in 200 sampling locations selected using conditioned Latin hypercube sampling. Additive sampling was designed to specifically explore SOC distribution near to hedges: 112 points were sampled at fixed distance on 14 transects perpendicular from hedges. We illustrate the heterogeneity of spatial and vertical distribution of SOC stocks at landscape scale, and quantify SOC stocks in the various landscape components. Using multivariate statistics, we discuss the variability and co-variability of existing spatial organization of cropping systems, environmental factors, and SOM stocks, over landscape. Ultimately, our results may contribute to improving regional or national digital soil mapping approaches, by considering the distribution of SOC stocks within each modeling unit and by accounting for the impact of sensitive ecosystems.

Comparative performance of high-density oligonucleotide sequencing and dideoxynucleotide sequencing of HIV type 1 pol from clinical samples.

PubMed

Günthard, H F; Wong, J K; Ignacio, C C; Havlir, D V; Richman, D D

1998-07-01

The performance of the high-density oligonucleotide array methodology (GeneChip) in detecting drug resistance mutations in HIV-1 pol was compared with that of automated dideoxynucleotide sequencing (ABI) of clinical samples, viral stocks, and plasmid-derived NL4-3 clones. Sequences from 29 clinical samples (plasma RNA, n = 17; lymph node RNA, n = 5; lymph node DNA, n = 7) from 12 patients, from 6 viral stock RNA samples, and from 13 NL4-3 clones were generated by both methods. Editing was done independently by a different investigator for each method before comparing the sequences. In addition, NL4-3 wild type (WT) and mutants were mixed in varying concentrations and sequenced by both methods. Overall, a concordance of 99.1% was found for a total of 30,865 bases compared. The comparison of clinical samples (plasma RNA and lymph node RNA and DNA) showed a slightly lower match of base calls, 98.8% for 19,831 nucleotides compared (protease region, 99.5%, n = 8272; RT region, 98.3%, n = 11,316), than for viral stocks and NL4-3 clones (protease region, 99.8%; RT region, 99.5%). Artificial mixing experiments showed a bias toward calling wild-type bases by GeneChip. Discordant base calls are most likely due to differential detection of mixtures. The concordance between GeneChip and ABI was high and appeared dependent on the nature of the templates (directly amplified versus cloned) and the complexity of mixes.

Forest Dynamics at the Missouri Ozark Forest Ecosystem Project viewed through stocking diagrams

Treesearch

David R. Larsen; John M. Kabrick; Stephen R. Shifley; Randy G. Jensen

2017-01-01

Stocking diagrams come in two forms, the Gingrich diagram and the density management diagram. While they both present the same information about a forest stand, they each provide a different perspective on the data being displayed. Density management diagrams have been around since the 1930s and the Gingrich diagram has been around since the 1960s, but applications of...

From Models to Measurements: Comparing Downed Dead Wood Carbon Stock Estimates in the U.S. Forest Inventory

PubMed Central

Domke, Grant M.; Woodall, Christopher W.; Walters, Brian F.; Smith, James E.

2013-01-01

The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.’s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles) in the conterminous U.S. was 9 percent (145.1 Tg) greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg) greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg) smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events. PMID:23544112

From models to measurements: comparing downed dead wood carbon stock estimates in the U.S. forest inventory.

PubMed

Domke, Grant M; Woodall, Christopher W; Walters, Brian F; Smith, James E

2013-01-01

The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.'s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles) in the conterminous U.S. was 9 percent (145.1 Tg) greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg) greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg) smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

Using an experimental manipulation to determine the effectiveness of a stock enhancement program

USGS Publications Warehouse

Stewart, David R.; Long, James M.

2015-01-01

We used an experimental manipulation to determine the impact of stocking 178 mm channel catfish Ictalurus punctatus in six impoundments. The study design consisted of equal numbers (two) of control, ceased-stock, and stocked treatments that were sampled one year before and two years after stocking. Relative abundance, growth, size structure, and average weight significantly changed over time based on samples collected with hoop nets. Catch rates decreased at both ceased-stock lakes and increased for one stocked lake, while growth rates changed for at least one ceased-stock and stocked lake. The average weight of channel catfish in the ceased-stock treatment increased by 6% and 25%, whereas weight decreased by 28% and 78% in both stocked lakes. The variability in observed responses between lakes in both ceased-stock and stocked treatments indicates that a one-size-fits-all stocking agenda is impractical, suggesting lake specific and density-dependent mechanisms affect channel catfish population dynamics.

Effects of genotype and population density on growth performance, carcass characteristics, and cost-benefits of broiler chickens in north central Nigeria.

PubMed

Yakubu, Abdulmojeed; Ayoade, John A; Dahiru, Yakubu M

2010-04-01

The influence of genotype and stocking densities on growth performance, carcass qualities, and cost-benefits of broilers were examined in a 28-day trial. Two hundred and seven 4-week-old birds each of Anak Titan and Arbor Acre hybrid broiler types were randomly assigned to three stocking density treatments of 8.3, 11.1, and 14.3 birds/m(2) in a 2 x 3 factorial arrangement. Final body weight, average weekly body weight and average weekly feed intake were affected (P < 0.05) by strain, with higher means recorded for Arbor Acres. However, average weekly body weight gain and feed conversion ratio were similar (P > 0.05) in both genetic groups. The effect of placement density on some growth parameters did not follow a linear trend. Arbor Acres had significantly (P < 0.05) higher relative (%) fasted body, carcass, back, neck, and wing weights compared to Anak Titans. Housing density effect (P < 0.05) was observed for relative (%) fasted body, shank, and wing weights of birds. However, the relative weights of visceral organs of birds were not significantly (P > 0.05) influenced by genotype and housing density. The economic analysis revealed that higher gross margin was recorded for Arbor Acres compared to Anak Titans (euro 2.76 versus euro 2.19; P < 0.05, respectively). Conversely, stocking rate did not exert any influence (P > 0.05) on profit margin. Genotype x stocking density interaction effect was significant for some of the carcass indices investigated. It is concluded that under sub-humid conditions of a tropical environment, the use of Arbor Acre genetic type as well as a placement density of 14.3 birds/m(2) appeared to be more profitable.

Past and prospective carbon stocks in forests of northern Wisconsin: a report from the Chequamegon-Nicolet National Forest Climate Change Response Framework

Treesearch

Richard Birdsey; Yude Pan; Maria Janowiak; Susan Stewart; Sarah Hines; Linda Parker; Stith Gower; Jeremy Lichstein; Kevin McCullough; Fangmin Zhang; Jing Chen; David Mladenoff; Craig Wayson; Chris Swanston

2014-01-01

This report assesses past and prospective carbon stocks for 4.5 million ha of forest land in northern Wisconsin, including a baseline assessment and analysis of the impacts of disturbance and management on carbon stocks. Carbon density (amount of carbon stock per unit area) averages 237 megagrams (Mg) per ha, with the National Forest lands having slightly higher carbon...

Multiaged silviculture of ponderosa pine

Treesearch

Kevin L. O' Hara

2005-01-01

Ponderosa pine (Pinus ponderosa P. & C. Lawson) is highly suitable for management using multiaged systems. This suitability is primarily the result of a frequent, low severity disturbance regime, but also because it naturally occurs at low densities and has a long history of management to promote multiple age classes. Several different stocking...

Top pruning

Treesearch

Thomas D. Landis

2005-01-01

Controlling plant height is always a challenge because shoot growth is stimulated in modem nursery environments (Figure 1). To further aggravate the problem, economics forces nurseries to grow their stock at high densities and so plants want to outgrow their neighbors. Inducing mild stresses helps to slow height growth but this has only limited application. Chemical...

Defoliation of Flourensia cernua (tarbush) with high-density mixed-species stocking

USDA-ARS?s Scientific Manuscript database

Interest in shrub use by livestock is increasing along with the rising demands placed on rangelands worldwide. Historically, Flourensia cernua (tarbush) has increased in the Chihuahuan Desert but receives limited use by cattle. Cattle, sheep and goats co-grazed eight 0.6 ha tarbush-dominated paddock...

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

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

White, G.C.

1989-03-01

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

A tree-by-tree measure of site utilization for grand fir related to stand density index

Treesearch

Albert R. Stage

1968-01-01

The usefulness of stand density index (SDI) has been limited by lack of a way to partition its nonlinear expression into additive components to describe the relative stocking of a stand by species or quality classes. In this paper, a linear equation is derived to permit such a partition. A closely related expression for grand fir stocking is given that retains the...

Developing Inventory Projection Models Using Empirical Net Forest Growth and Growing-Stock Density Relationships Across U.S. Regions and Species Group

Treesearch

Prakash Nepal; Peter J. Ince; Kenneth E. Skog; Sun J. Chang

2012-01-01

This paper describes a set of empirical net forest growth models based on forest growing-stock density relationships for three U.S. regions (North, South, and West) and two species groups (softwoods and hardwoods) at the regional aggregate level. The growth models accurately predict historical U.S. timber inventory trends when we incorporate historical timber harvests...

Predator response to releases of American shad larvae in the Susquehanna River basin

USGS Publications Warehouse

Johnson, James H.; Ringler, N.H.

1998-01-01

Predation on American shad (Alosa sapidissima) larvae within the first two hours of release was examined from 1989 to 1992 on 31 occasions at stocking sites in the Susquehanna River basin. Twenty-two fish species consumed shad larvae; the dominant predators were spotfin shiner (Cyprinella spiloptera), mimic shiner (Notropis volucellus) and juvenile smallmouth bass (Micropterus dolomieu). The number of shad larvae found in predator stomachs ranged from 0 to 900. Mortality of shad larvae at the stocking site was usually less than 2%. The greatest mortality (9.6%) occurred at the highest stocking level (1.5 million larvae). Highly variable predation rates and release levels of shad insufficient to achieve predator satiation hindered the ability to determine a specific type of functional response of predators. Predator numbers increased with stocking density, indicating short-term aggregation at the release site. Because of practical problems associated with releasing the large numbers of larvae that would be required to satiate predators, routine stocking at these levels is probably unreasonable. Releases of 400,000 to 700,000 larvae may reduce predation by offsetting depensatory mechanisms that operate on small releases and the effects of increased predation due to predator aggregation on large releases. Night stocking may reduce predation on larval shad at the release site.

Stocking density, milking duration, and lying times of lactating cows on Canadian freestall dairy farms.

PubMed

Charlton, G L; Haley, D B; Rushen, J; de Passillé, A M

2014-05-01

Lying time is an important measure of cow comfort, and the lying behavior of dairy cattle can now be recorded automatically with the use of accelerometers. To assess the effect that stall stocking density and the time that cows spend away from the home pen being milked has on the lying behavior of Holstein cattle, a total of 111 commercial freestall dairy farms were visited in Canada. Accelerometers were used to automatically record the lying behavior of 40 focal cows per farm. Total duration of lying, lying bout frequency, and the mean duration of lying bouts were calculated. Pen population was the total number of cows in the pen. To calculate stall stocking density (%) the number of cows in the pen and the number of useable stalls were counted and multiplied by 100, and the length × width of the pen was divided by the number of cows in the pen to calculate area/cow (m(2)). Time away from the pen per day was recorded from when the first cow in each pen was taken out of the home pen for milking until the last cow returned to the home pen after milking, and this time was multiplied by daily milking frequency. The median value for lying duration at the farm level was 10.6h/d, with 10.5 lying bouts/d, and a median lying bout duration of 1.2h. Stall stocking density ranged from 52.2 to 160.0%, with very few farms (7%) stocking at greater than 120%. Although stall stocking density was not significantly correlated with lying behavior, the results showed that no farm with stocking density greater that 100% achieved an average herd lying duration of 12h/d or higher, whereas 21.6% of farms with a stocking density of 100% or less did achieve the target lying time of ≥ 12 h/d, as recommended by the Canadian Code of Practice (χ(2)=4.86, degrees of freedom = 1). Area/cow (m(2)) was not correlated with any aspect of lying behavior, but regardless of space per cow, pen population was correlated with daily frequency and duration of lying bouts. As the number of cows in the pen increased, lying daily bout frequency increased (correlation coefficient = 0.24) and lying bout duration decreased (correlation coefficient = -0.30). Lying behavior was affected by the time the cows were away from the pen being milked. When cows were away from the pen for longer than 3.7h/d, no farm achieved the recommended herd median lying time of 12h/d or longer. These results suggest that providing 1 stall for each cow in the pen and minimizing time away from the pen are important factors if cattle are to achieve the recommended daily lying duration of 12h/d. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Environmental and management factors affecting the welfare of chickens on commercial farms in the United Kingdom and Denmark stocked at five densities.

PubMed

Jones, T A; Donnelly, C A; Stamp Dawkins, M

2005-08-01

Data from a large commercial-scale experiment in which 10 major broiler producer companies stocked whole houses of birds at 30, 34, 38, 42, and 46 kg/m2 were analyzed to identify 1) temperature and humidity profiles achieved throughout the growth cycle, 2) management practices and equipment that contributed to observed variation in environmental conditions, and 3) the extent to which environmental variables affected bird welfare. The study involved a total of 2.7 million birds in 114 houses on commercial farms with measurement of a wide range of environmental and bird variables. Much of the variation in broiler health and welfare was associated with the percentage of time a company could maintain house temperature and RH within limits recommended by the breeder company. RH in the first week of life was particularly important to later health, suggesting that better control of humidity might lead to improved welfare. Key management factors affecting bird welfare were those relating to good ventilation and air control such as the type of ventilation, type of drinker, numbers of stockmen, and litter type. Controlling the environment, particularly temperature, humidity, and air and litter quality, is crucial to broiler chicken welfare. This does not mean that stocking density is unimportant, but lowering stocking density on its own, without regard to the environment the birds experience, is not sufficient. Genuine improvements in bird welfare will come from setting standards that combine stocking density, safeguards on the environment, and the genetic makeup of the birds.

Does pulse-grazing influence within- and between-grazing season dietary quality of yearling steers in shortgrass steppe?

USDA-ARS?s Scientific Manuscript database

Pulse-grazing, high stock density with short grazing periods (weeks) followed by long (months to > 1 year) rest periods, is a grazing management strategy posited to decrease preferential selection by cattle and increase utilization of forage, but influences on dietary quality of grazing animals in s...

Hematology and plasma chemistry reference intervals for cultured tilapia (Oreochromis hybrid).

PubMed

Hrubec, Terry C.; Cardinale, Jenifer L.; Smith, Stephen A.

2000-01-01

Tilapia are a commonly aquacultured fish yet little is known about their normal physiology and response to disease. In this study we determined the results of complete hematologic (n=40) and plasma biochemical profiles (n=63) in production tilapia (Oreochromis hybrids). The fish were raised in recirculating systems with a high stocking density (120 g/L), and were in the middle of a 15-month production cycle. Blood was analyzed using standard techniques, and reference intervals were determined using nonparametric methods. Non-production tilapia (n=15) from low-density tanks (4 g/L) also were sampled; the clinical chemistry results were compared to reference intervals from the fish raised in high-density tanks. Differences were noted in plasma protein, calcium and phosphorus concentrations, such that reference intervals for high-density production tilapia were not applicable to fish raised under different environmental and management conditions.

Predicting Stand and Stock Tables from a Spacing Study in Naturally Regenerated Longleaf Pine

Treesearch

Robert M. Farrar

1985-01-01

A prediction system is presented whereby stand and stock tables are calculated for young natural longleaf pine stands of varying initial density. Tables can be output for stand conditions of 10 to 20 years of age, 300 to 1,500 initial trees per acre (at age lo), and 70 to 80 feet in site index (index age 50). The system also allows one to translate from density...

Short-term increases in stocking density affect the lying and social behavior, but not the productivity, of lactating Holstein dairy cows.

PubMed

Krawczel, P D; Klaiber, L B; Butzler, R E; Klaiber, L M; Dann, H M; Mooney, C S; Grant, R J

2012-08-01

Reduced access to resources because of increased stocking density may have a detrimental effect on the behavior of the lactating dairy cow. The objective of this study was to determine the short-term responses in behavior, productivity, fecal cortisol metabolites, and udder and leg hygiene of lactating Holstein dairy cows housed at stocking densities of 100 (1 cow per freestall and headlock), 113, 131, and 142%. Multiparous cows (n=92) and primiparous cows (n=44) were assigned to 1 of 4 pens (34 cows per pen) in a 4-row freestall barn. Pens were balanced for parity, milk production, and days in milk. Stocking densities were imposed for 14 d using a 4 × 4 Latin square design. Time spent feeding and time spent ruminating were quantified by 24 h of direct observation of focal cows (n=12 per pen) beginning at 0800 h on d 11 of each period. Data loggers recorded lying behavior (time and bouts) from the same focal cows per pen at 1-min intervals during the final 5 d of each period. Fecal cortisol metabolites were quantified from samples collected on d 13 and 14 of each period from the same focal cows. Displacements from the feed barrier were recorded on a pen basis after 9 milkings over the last 4 d of each period. Productivity was assessed on a pen basis from milk yield (recorded from d 10 to 14 of each period) and milk components (quantified from composite samples collected on d 12 of each period). Milk composition was further analyzed for milk fatty acid profiles, which were determined from a subset (n=6 per pen) of the focal cows. Data were analyzed using the MIXED procedure of SAS, with the pen (n=4 per treatment, except displacements where n=3 per treatment) as the experimental unit. Feeding and ruminating (h/d) did not differ among treatments. Lying time was reduced at stocking densities of 131 and 142%, relative to 100 or 113%. Lying bouts were not affected by treatment. Stocking densities of 131 and 142% reduced the percentage of time cows spent ruminating within a freestall relative to 100%. Displacements from the feed bunk increased linearly across treatments. Fecal cortisol metabolites, udder hygiene score, milk yields, milk composition, and milk fatty acids did not differ among treatments. Decreased lying time and increased aggression at the feed bunk suggest that an alteration of the time budgets of lactating dairy cows may occur at higher stocking densities, but it is unclear at what point these changes might have further biological consequences. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A statistical analysis of UK financial networks

NASA Astrophysics Data System (ADS)

Chu, J.; Nadarajah, S.

2017-04-01

In recent years, with a growing interest in big or large datasets, there has been a rise in the application of large graphs and networks to financial big data. Much of this research has focused on the construction and analysis of the network structure of stock markets, based on the relationships between stock prices. Motivated by Boginski et al. (2005), who studied the characteristics of a network structure of the US stock market, we construct network graphs of the UK stock market using same method. We fit four distributions to the degree density of the vertices from these graphs, the Pareto I, Fréchet, lognormal, and generalised Pareto distributions, and assess the goodness of fit. Our results show that the degree density of the complements of the market graphs, constructed using a negative threshold value close to zero, can be fitted well with the Fréchet and lognormal distributions.

Effect of less intensive rearing conditions on litter characteristics, growth performance, carcase injuries and meat quality of broilers.

PubMed

Meluzzi, A; Fabbri, C; Folegatti, E; Sirri, F

2008-09-01

1. The objective was to compare the effect of two litter types (wheat straw and wood shavings) and two different rearing conditions (Treated and Control) on welfare indicators, broiler performance, carcase injuries, particularly hock and foot pad dermatitis (FPD), litter characteristics and meat quality. 2. Treated conditions were characterised by a low stocking density (11 birds/m(2)), short photoperiod (16 h light: 8 h dark) and a large amount of litter (3 to 4.5 kg/m(2), respectively, for wheat straw or wood shavings). Control conditions were a high stocking density (14 birds/m(2)), long photoperiod (23 h light:1 h dark) and small amount of litter (2.3 to 3 kg/m(2), respectively, for wheat straw or wood shavings). In addition, the effects of two widely used litter materials, wheat straw and wood shavings, were investigated. 3. The combined effects of lower stocking density, greater amount of litter material and a photoperiod similar to the natural one, reduced the occurrence of FPD in Treated groups keeping the FPD score under the European threshold. 4. Improved rearing conditions led to faster growth rate associated with inferior feed efficiency, whereas litter type exerted negligible effects on broiler performance. 5. Litter moisture content, nitrogen and ammonia released by the litter were lower in Treated groups than Control groups. The use of wood shavings resulted in lower moisture and nitrogen concentrations in the litter.

Increasing leaf vein density by mutagenesis: laying the foundations for C4 rice.

PubMed

Feldman, Aryo B; Murchie, Erik H; Leung, Hei; Baraoidan, Marietta; Coe, Robert; Yu, Su-May; Lo, Shuen-Fang; Quick, William P

2014-01-01

A high leaf vein density is both an essential feature of C4 photosynthesis and a foundation trait to C4 evolution, ensuring the optimal proportion and proximity of mesophyll and bundle sheath cells for permitting the rapid exchange of photosynthates. Two rice mutant populations, a deletion mutant library with a cv. IR64 background (12,470 lines) and a T-DNA insertion mutant library with a cv. Tainung 67 background (10,830 lines), were screened for increases in vein density. A high throughput method with handheld microscopes was developed and its accuracy was supported by more rigorous microscopy analysis. Eight lines with significantly increased leaf vein densities were identified to be used as genetic stock for the global C4 Rice Consortium. The candidate population was shown to include both shared and independent mutations and so more than one gene controlled the high vein density phenotype. The high vein density trait was found to be linked to a narrow leaf width trait but the linkage was incomplete. The more genetically robust narrow leaf width trait was proposed to be used as a reliable phenotypic marker for finding high vein density variants in rice in future screens.

Status and trends of the rainbow trout population in the Lees Ferry reach of the Colorado River downstream from Glen Canyon Dam, Arizona, 1991–2009

USGS Publications Warehouse

Makinster, Andrew S.; Persons, William R.; Avery, Luke A.

2011-01-01

The Lees Ferry reach of the Colorado River, a 25-kilometer segment of river located immediately downstream from Glen Canyon Dam, has contained a nonnative rainbow trout (Oncorhynchus mykiss) sport fishery since it was first stocked in 1964. The fishery has evolved over time in response to changes in dam operations and fish management. Long-term monitoring of the rainbow trout population downstream of Glen Canyon Dam is an essential component of the Glen Canyon Dam Adaptive Management Program. A standardized sampling design was implemented in 1991 and has changed several times in response to independent, external scientific-review recommendations and budget constraints. Population metrics (catch per unit effort, proportional stock density, and relative condition) were estimated from 1991 to 2009 by combining data collected at fixed sampling sites during this time period and at random sampling sites from 2002 to 2009. The validity of combining population metrics for data collected at fixed and random sites was confirmed by a one-way analysis of variance by fish-length class size. Analysis of the rainbow trout population metrics from 1991 to 2009 showed that the abundance of rainbow trout increased from 1991 to 1997, following implementation of a more steady flow regime, but declined from about 2000 to 2007. Abundance in 2008 and 2009 was high compared to previous years, which was likely the result of increased early survival caused by improved habitat conditions following the 2008 high-flow experiment at Glen Canyon Dam. Proportional stock density declined between 1991 and 2006, reflecting increased natural reproduction and large numbers of small fish in samples. Since 2001, the proportional stock density has been relatively stable. Relative condition varied with size class of rainbow trout but has been relatively stable since 1991 for fish smaller than 152 millimeters (mm), except for a substantial decrease in 2009. Relative condition was more variable for larger size classes, and substantial decreases were observed for the 152-304-mm size class in 2009 and 305-405-mm size class in 2008 that persisted into 2009.

Urban Land Use Change Effects on Below and Aboveground Carbon Stocks—a Global Perspective and Future Research Needs

NASA Astrophysics Data System (ADS)

Pouyat, R. V.; Chen, Y.; Yesilonis, I.; Day, S.

2014-12-01

Land use change (LUC) has a significant impact on both above- and below-ground carbon (C) stocks; however, little is known about the net effects of urban LUC on the C cycle and climate system. Moreover, as climate change becomes an increasingly pressing concern, there is growing evidence that urban policy and management decisions can have significant regional impacts on C dynamics. Soil organic carbon (SOC) varies significantly across ecoregions at global and continental scales due to differential sensitivity of primary production, substrate quality, and organic matter decay to changes in temperature and soil moisture. These factors are highly modified by urban LUC due to vegetation removal, soil relocation and disruption, pollution, urban heat island effects, and increased atmospheric CO2 concentrations. As a result, on a global scale urban LUC differentially affects the C cycle from ecoregion to ecoregion. For urban ecosystems, the data collected thus far suggests urbanization can lead to both an increase and decrease in soil C pools and fluxes, depending on the native ecosystem being impacted by urban development. For example, in drier climates, urban landscapes accumulate higher C densities than the native ecosystems they replaced. Results suggest also that soil C storage in urban ecosystems is highly variable with very high (> 20.0) and low (< 2.0) C densities (kg m-2 to a 1 m depth) present in the landscape at any one time. Moreover, similar to non-urban soils, total SOC densities are consistently 2-fold greater than aboveground stocks. For those soils with low SOC densities, there is potential to increase C sequestration through management, but specific urban related management practices need to be evaluated. In addition, urban LUC is a human-driven process and thus can be modified or adjusted to reduce its impacts on the C cycle. For example, policies that influence development patterns, population density, management practices, and other human factors can greatly ameliorate the impact of urban LUC on the C cycle. However, even with the recent and rapid expansion of newly acquired data, the net effects of urban LUC on C stocks and fluxes have not been comprehensively addressed. Furthermore, how sensitive these changes are to urban planning, policy decisions, and site management needs to be explored.

Impacts of Daily Bag Limit Reductions on Angler Effort in Wisconsin Walleye Lakes

USGS Publications Warehouse

Beard, T.D.; Cox, S.P.; Carpenter, S.R.

2003-01-01

Angler effort is an important factor affecting recreational fisheries. However, angler responses are rarely incorporated into recreational fisheries regulations or predictions. Few have attempted to examine how daily bag limit regulations affect total angling pressure and subsequent stock densities. Our paper develops a theoretical basis for predicting angler effort and harvest rate based on stock densities and bag limit regulations. We examined data from a management system that controls the total exploitation of walleyes Sander vitreus (formerly Stizostedion vitreum) in northern Wisconsin lakes and compared these empirical results with the predictions from a theoretical effort and harvest rate response model. The data indicated that higher general angler effort occurs on lakes regulated with a 5-walleye daily limit than on lakes regulated with either a 2- or 3-walleye daily limit. General walleye catch rates were lower on lakes with a 5-walleye limit than on lakes with either a 2- or 3-walleye daily limit. An effort response model predicted a logarithmic relationship between angler effort and adult walleye density and that an index of attractiveness would be greater on lakes with high bag limits. Predictions from the harvest rate model with constant walleye catchability indicated that harvest rates increased nonlinearly with increasing density. When the effort model was fitted to data from northern Wisconsin, we found higher lake attractiveness at 5-walleye-limit lakes. We conclude that different groups of anglers respond differently to bag limit changes and that reliance on daily bag limits may not be sufficient to maintain high walleye densities in some lakes in this region.

Derivation of a northern-hemispheric biomass map for use in global carbon cycle models

NASA Astrophysics Data System (ADS)

Thurner, Martin; Beer, Christian; Santoro, Maurizio; Carvalhais, Nuno; Wutzler, Thomas; Schepaschenko, Dmitry; Shvidenko, Anatoly; Kompter, Elisabeth; Levick, Shaun; Schmullius, Christiane

2013-04-01

Quantifying the state and the change of the World's forests is crucial because of their ecological, social and economic value. Concerning their ecological importance, forests provide important feedbacks on the global carbon, energy and water cycles. In addition to their influence on albedo and evapotranspiration, they have the potential to sequester atmospheric carbon dioxide and thus to mitigate global warming. The current state and inter-annual variability of forest carbon stocks remain relatively unexplored, but remote sensing can serve to overcome this shortcoming. While for the tropics wall-to-wall estimates of above-ground biomass have been recently published, up to now there was a lack of similar products covering boreal and temperate forests. Recently, estimates of forest growing stock volume (GSV) were derived from ENVISAT ASAR C-band data for latitudes above 30° N. Utilizing a wood density and a biomass compartment database, a forest carbon density map covering North-America, Europe and Asia with 0.01° resolution could be derived out of this dataset. Allometric functions between stem, branches, root and foliage biomass were fitted and applied for different leaf types (broadleaf, needleleaf deciduous, needleleaf evergreen forest). Additionally, this method enabled uncertainty estimation of the resulting carbon density map. Intercomparisons with inventory-based biomass products in Russia, Europe and the USA proved the high accuracy of this approach at a regional scale (r2 = 0.70 - 0.90). Based on the final biomass map, the forest carbon stocks and densities (excluding understorey vegetation) for three biomes were estimated across three continents. While 40.7 ± 15.7 Gt of carbon were found to be stored in boreal forests, temperate broadleaf/mixed forests and temperate conifer forests contain 24.5 ± 9.4 Gt(C) and 14.5 ± 4.8 Gt(C), respectively. In terms of carbon density, most of the carbon per area is stored in temperate conifer (62.1 ± 20.7 Mg(C)/ha(Forest)) and broadleaf/mixed forests (58.0 ± 22.1 Mg(C)/ha(Forest)), whereas boreal forests have a carbon density of only 40.0 ± 15.4 Mg(C)/ha(Forest). While European forest carbon stocks are relatively small, the carbon density is higher compared to the other continents. The derived biomass map substantially improves the knowledge on the current carbon stocks of the northern-hemispheric boreal and temperate forests, serving as a new benchmark for spatially explicit and consistent biomass mapping with moderate spatial resolution. This product can be of great value for global carbon cycle models as well as national carbon monitoring systems. Further investigations concentrate on improving biomass parameterizations and representations in such kind of models. The presented map will help to improve the simulation of biomass spatial patterns and variability and enables identifying the dominant influential factors like climatic conditions and disturbances.

Forest plantations in the Midsouth, U.S.A.

Treesearch

James F. Rosson

1995-01-01

Timberland that has been artificially regenerated in the seven Midsouth States was analyzed by ownership, forest type, stocking class, age, tree density, basal area, site class, and volume. Growing-stock volumes of natural stands and plantations were compared.

Scaling in the distribution of intertrade durations of Chinese stocks

NASA Astrophysics Data System (ADS)

Jiang, Zhi-Qiang; Chen, Wei; Zhou, Wei-Xing

2008-10-01

The distribution of intertrade durations, defined as the waiting times between two consecutive transactions, is investigated based upon the limit order book data of 23 liquid Chinese stocks listed on the Shenzhen Stock Exchange in the whole year 2003. A scaling pattern is observed in the distributions of intertrade durations, where the empirical density functions of the normalized intertrade durations of all 23 stocks collapse onto a single curve. The scaling pattern is also observed in the intertrade duration distributions for filled and partially filled trades and in the conditional distributions. The ensemble distributions for all stocks are modeled by the Weibull and the Tsallis q-exponential distributions. Maximum likelihood estimation shows that the Weibull distribution outperforms the q-exponential for not-too-large intertrade durations which account for more than 98.5% of the data. Alternatively, nonlinear least-squares estimation selects the q-exponential as a better model, in which the optimization is conducted on the distance between empirical and theoretical values of the logarithmic probability densities. The distribution of intertrade durations is Weibull followed by a power-law tail with an asymptotic tail exponent close to 3.

The roles of the trading time risks on stock investment return and risks in stock price crashes

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Dong, Zhi-Wei; Yang, Guo-Hui; Long, Chao

2017-03-01

The roles of the trading time risks (TTRs) on stock investment return and risks are investigated in the condition of stock price crashes with Hushen300 data (CSI300) and Dow Jones Industrial Average (ˆDJI), respectively. In order to describe the TTR, we employ the escape time that the stock price drops from the maximum to minimum value in a data window length (DWL). After theoretical and empirical research on probability density function of return, the results in both ˆDJI and CSI300 indicate that: (i) As increasing DWL, the expectation of returns and its stability are weakened. (ii) An optimal TTR is related to a maximum return and minimum risk of stock investment in stock price crashes.

Carbon stock of Moso bamboo (Phyllostachys pubescens) forests along a latitude gradient in the subtropical region of China.

PubMed

Xu, Mengjie; Ji, Haibao; Zhuang, Shunyao

2018-01-01

Latitude is an important factor that influences the carbon stock of Moso bamboo (Phyllostachys pubescens) forests. Accurate estimation of the carbon stock of Moso bamboo forest can contribute to sufficient evaluation of forests in carbon sequestration worldwide. Nevertheless, the effect of latitude on the carbon stock of Moso bamboo remains unclear. In this study, a field survey with 36 plots of Moso bamboo forests along a latitude gradient was conducted to investigate carbon stock. Results showed that the diameter at breast height (DBH) of Moso bamboo culms increased from 8.37 cm to 10.12 cm that well fitted by Weibull model, whereas the bamboo culm density decreased from 4722 culm ha-1 to 3400 culm ha-1 with increasing latitude. The bamboo biomass carbon decreased from 60.58 Mg C ha-1 to 48.31 Mg C ha-1 from north to south. The total carbon stock of Moso bamboo forests, which comprises soil and biomass carbon, ranged from 87.83 Mg C ha-1 to 119.5 Mg C ha-1 and linearly increased with latitude. As a fast-growing plant, Moso bamboo could be harvested amounts of 6.0 Mg C ha-1 to 7.6 Mg C ha-1 annually, which indicates a high potential of this species for carbon sequestration. Parameters obtained in this study can be used to accurately estimate the carbon stock of Moso bamboo forest to establish models of the global carbon balance.

Carbon stock of Moso bamboo (Phyllostachys pubescens) forests along a latitude gradient in the subtropical region of China

PubMed Central

Xu, Mengjie; Ji, Haibao

2018-01-01

Latitude is an important factor that influences the carbon stock of Moso bamboo (Phyllostachys pubescens) forests. Accurate estimation of the carbon stock of Moso bamboo forest can contribute to sufficient evaluation of forests in carbon sequestration worldwide. Nevertheless, the effect of latitude on the carbon stock of Moso bamboo remains unclear. In this study, a field survey with 36 plots of Moso bamboo forests along a latitude gradient was conducted to investigate carbon stock. Results showed that the diameter at breast height (DBH) of Moso bamboo culms increased from 8.37 cm to 10.12 cm that well fitted by Weibull model, whereas the bamboo culm density decreased from 4722 culm ha−1 to 3400 culm ha−1 with increasing latitude. The bamboo biomass carbon decreased from 60.58 Mg C ha−1 to 48.31 Mg C ha−1 from north to south. The total carbon stock of Moso bamboo forests, which comprises soil and biomass carbon, ranged from 87.83 Mg C ha−1 to 119.5 Mg C ha−1 and linearly increased with latitude. As a fast-growing plant, Moso bamboo could be harvested amounts of 6.0 Mg C ha−1 to 7.6 Mg C ha−1 annually, which indicates a high potential of this species for carbon sequestration. Parameters obtained in this study can be used to accurately estimate the carbon stock of Moso bamboo forest to establish models of the global carbon balance. PMID:29451911

Artificial propagation of coregonines in the management of the Laurentian Great Lakes

USGS Publications Warehouse

Todd, Thomas N.

1986-01-01

Numerous stresses caused wide fluctuations in the abundance of Great Lakes coregonine fishes during the last century. State, Provincial, and Federal agencies attempted to bolster these fisheries by stocking more than 32 billion fry of lake whitefish (Coregonus clupeaformis) and 6 billion fry of lake herring (C. artedii) over a period of about 90 years (1870-1960). Propagation efforts were unsuccessful in arresting the decline of these fishes, perhaps because the stocking densities were too low. It appears that stocking densities must exceed 41% of the natural hatch to produce measurable success in a planting program that augments natural reproduction. Stocking of any of the Great Lakes with lake whitefish at these levels would require several billion fry per lake annually. Such a program is too large to be practical and intensified protection of the remaining stocks would be more cost effective. A species such as the shortnose cisco (C. reighardi) which has only a small number of extant individuals, and can therefore be significantly augmented with fewer stocked fish, may be a much better candidate for propagation than is the lake whitefish. Propagation of coregonines in the Great Lakes should be considered only in localities that have little or no natural recruitment and then only for rehabilitation, and only if accompanied by adequate assessment of the performance of the stocked fish.

Impact of deforestation on soil carbon stock and its spatial distribution in the Western Black Sea Region of Turkey.

PubMed

Kucuker, Mehmet Ali; Guney, Mert; Oral, H Volkan; Copty, Nadim K; Onay, Turgut T

2015-01-01

Land use management is one of the most critical factors influencing soil carbon storage and the global carbon cycle. This study evaluates the impact of land use change on the soil carbon stock in the Karasu region of Turkey which in the last two decades has undergone substantial deforestation to expand hazelnut plantations. Analysis of seasonal soil data indicated that the carbon content decreased rapidly with depth for both land uses. Statistical analyses indicated that the difference between the surface carbon stock (defined over 0-5 cm depth) in agricultural and forested areas is statistically significant (Agricultural = 1.74 kg/m(2), Forested = 2.09 kg/m(2), p = 0.014). On the other hand, the average carbon stocks estimated over the 0-1 m depth were 12.36 and 12.12 kg/m(2) in forested and agricultural soils, respectively. The carbon stock (defined over 1 m depth) in the two land uses were not significantly different which is attributed in part to the negative correlation between carbon stock and bulk density (-0.353, p < 0.01). The soil carbon stock over the entire study area was mapped using a conditional kriging approach which jointly uses the collected soil carbon data and satellite-based land use images. Based on the kriging map, the spatially soil carbon stock (0-1 m dept) ranged about 2 kg/m(2) in highly developed areas to more than 23 kg/m(2) in intensively cultivated areas as well as the averaged soil carbon stock (0-1 m depth) was estimated as 10.4 kg/m(2). Copyright © 2014 Elsevier Ltd. All rights reserved.

Biological control experiment of excess propagation of Cyclops for drinking water security.

PubMed

Lin, Tao; Cui, Fu-Yi; Liu, Dong-Mei

2007-01-01

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this study, an ecological project was put forward for the excess propagation control of Cyclops by stocking the filter-feeding fishes such as silver carp and bighead carp under the condition of no extraneous nutrient feeding. The results of experiments with different stocking biomass showed that the propagation of Cyclops could be controlled effectively, and the water quality was improved simultaneously by impacting on nutriment level and plankton community structure at proper stocking density of 30 g/m3 of water. The growth of Cyclops may not be effectually controlled with lower biomass of fish (10 g), and the natural food chain relation may be destroyed for Cyclops dying out in water while the intense stocking of 120 g per cubic meter of water. In addition, the high predator pressure may accelerate supplemental rate of nutrients from bottom sediments to water body to add the content of total nitrogen and phosphorus in water.

[Faunal characteristics and distribution pattern of crustaceans in the vicinity of Pearl River estuary].

PubMed

Huang, Zi-Rong; Sun, Dian-Rong; Chen, Zuo-Zhi; Zhang, Han-Hua; Wang, Xue-Hui; Wang, Yue-Zhong; Fang, Hong-Da; Dong, Yan-Hong

2009-10-01

Based on the data of bottom trawl surveys in the vicinity of Pearl River estuary in August (summer), October (autumn), December (winter) 2006, and April (spring) 2007, the faunal characteristics and distribution pattern of crustaceans were analyzed. A total of 54 species belonging to 25 genera, 17 families, and 2 orders were collected, including 22 species of shrimps, 22 species of crabs, and 10 species of squills. Most of the crustaceans were tropical-subtropical warm-water species, a few of them were eurythermal species, and no warm-water and cold-water species occurred. Euryhaline species were most abundant, followed by halophile species, and the low-salinity species were the least. Most of the crustacean species belonged to the fauna of Indian Ocean-western Pacific Ocean. The faunal assemblages were closer to those of the East China Sea, Philippine Sea, Indonesia Sea, and the Japan Sea, and estranger with those of the Yellow Sea, Bohai Sea, and Korea Sea. The dominant species were Metapenaeus joyner, Oratosquilla oratoria, Charybdis miles, Portunus sanguinolentus, Harpiosquilla harpax, Charybdis feriatus, Charybdis japonica, Oratosquilla nepa, Solenocera crassicornis, Portunus trituberculatus, and Calappa philargius. The crustaceans had the largest species number (33) in autumn and the least one (26) in spring, and the highest stock density at the water depth of < 40 m, especially at 10-20 m. The average stock density of the crustaceans was estimated to be 99.60 kg x km(-2), with the highest (198.93 kg x km(-2)) in summer and the lowest (42.35 kg x km(-2)) in spring. Of the 3 species groups, crabs had the highest stock density (41.81 kg x km(-2)), followed by shrimps (38.91 kg x km(-2)), and squills (18.88 kg x km(-2)). The stock densities of the 3 species groups showed an obvious seasonal variation. Shrimps had the highest stock density (120.32 kg x km(-2)) in summer and the lowest density (0.67 kg x km(-2)) in spring, while crabs and squills had the highest density (62.01 and 29.49 kg x km(-2), respectively) in winter and the lowest density (24.64 and 6.30 kg x km(-2), respectively) in autumn.

Lumber recovery from small-diameter ponderosa pine from Flagstaff, Arizona

Treesearch

Eini C. Lowell; David W. Green

2001-01-01

Thousands of acres of densely stocked ponderosa pine forests surround Flagstaff, AZ. These stands are at high risk of fire, insect, and disease outbreak. Stand density management activity can be expensive, but product recovery from the thinned material could help defray removal costs. This project evaluated the yield and economic return of lumber recovered from small-...

Effects of deer exclosures on oak regeneration in closed-canopy stands

Treesearch

Angela M. Yuska; Kim C. Steiner; James C. Finley

2008-01-01

Studies of the effects of high deer densities on forest regeneration have shown altered species composition and reduced diversity in stands regenerating after harvest. The effects of browsing in fully stocked, undisturbed stands are less well known but important, as establishment of seedlings of oaks and other species prior to disturbance is very important for self-...

High-resolution forest carbon stocks and emissions in the Amazon.

PubMed

Asner, Gregory P; Powell, George V N; Mascaro, Joseph; Knapp, David E; Clark, John K; Jacobson, James; Kennedy-Bowdoin, Ty; Balaji, Aravindh; Paez-Acosta, Guayana; Victoria, Eloy; Secada, Laura; Valqui, Michael; Hughes, R Flint

2010-09-21

Efforts to mitigate climate change through the Reduced Emissions from Deforestation and Degradation (REDD) depend on mapping and monitoring of tropical forest carbon stocks and emissions over large geographic areas. With a new integrated use of satellite imaging, airborne light detection and ranging, and field plots, we mapped aboveground carbon stocks and emissions at 0.1-ha resolution over 4.3 million ha of the Peruvian Amazon, an area twice that of all forests in Costa Rica, to reveal the determinants of forest carbon density and to demonstrate the feasibility of mapping carbon emissions for REDD. We discovered previously unknown variation in carbon storage at multiple scales based on geologic substrate and forest type. From 1999 to 2009, emissions from land use totaled 1.1% of the standing carbon throughout the region. Forest degradation, such as from selective logging, increased regional carbon emissions by 47% over deforestation alone, and secondary regrowth provided an 18% offset against total gross emissions. Very high-resolution monitoring reduces uncertainty in carbon emissions for REDD programs while uncovering fundamental environmental controls on forest carbon storage and their interactions with land-use change.

Altitudinal variation of soil organic carbon stocks in temperate forests of Kashmir Himalayas, India.

PubMed

Ahmad Dar, Javid; Somaiah, Sundarapandian

2015-02-01

Soil organic carbon stocks were measured at three depths (0-10, 10-20, and 20-30 cm) in seven altitudes dominated by different forest types viz. Populus deltoides, 1550-1800 m; Juglans regia, 1800-2000 m; Cedrus deodara, 2050-2300 m; Pinus wallichiana, 2000-2300 m; mixed type, 2200-2400 m; Abies pindrow, 2300-2800 m; and Betula utilis, 2800-3200 m in temperate mountains of Kashmir Himalayas. The mean range of soil organic carbon (SOC) stocks varied from 39.07 to 91.39 Mg C ha(-1) in J. regia and B. utilis forests at 0-30 cm depth, respectively. Among the forest types, the lowest mean range of SOC at three depths (0-10, 10-20, and 20-30 cm) was observed in J. regia (18.55, 11.31, and 8.91 Mg C ha(-1), respectively) forest type, and the highest was observed in B. utilis (54.10, 21.68, and 15.60 Mg C ha(-1), respectively) forest type. SOC stocks showed significantly (R (2) = 0.67, P = 0.001) an increasing trend with increase in altitude. On average, the percentages of SOC at 0-10-, 10-20-, and 20-30-cm depths were 53.2, 26.5, and 20.3 %, respectively. Bulk density increased significantly with increase in soil depth and decreased with increase in altitude. Our results suggest that SOC stocks in temperate forests of Kashmir Himalaya vary greatly with forest type and altitude. The present study reveals that SOC stocks increased with increase in altitude at high mountainous regions. Climate change in these high mountainous regions will alter the carbon sequestration potential, which would affect the global carbon cycle.

Access to syringes for HIV prevention for injection drug users in St. Petersburg, Russia: syringe purchase test study

PubMed Central

2013-01-01

Background The HIV epidemic in Russia is concentrated among injection drug users (IDUs). This is especially true for St. Petersburg where high HIV incidence persists among the city’s estimated 80,000 IDUs. Although sterile syringes are legally available, access for IDUs may be hampered. To explore the feasibility of using pharmacies to expand syringe access and provide other prevention services to IDUs, we investigated the current access to sterile syringes at the pharmacies and the correlation between pharmacy density and HIV prevalence in St. Petersburg. Methods 965 pharmacies citywide were mapped, classified by ownership type, and the association between pharmacy density and HIV prevalence at the district level was tested. We selected two districts among the 18 districts – one central and one peripheral – that represented two major types of city districts and contacted all operating pharmacies by phone to inquire if they stocked syringes and obtained details about their stock. Qualitative interviews with 26 IDUs provided data regarding syringe access in pharmacies and were used to formulate hypotheses for the pharmacy syringe purchase test wherein research staff attempted to purchase syringes in all pharmacies in the two districts. Results No correlation was found between the density of pharmacies and HIV prevalence at the district level. Of 108 operating pharmacies, 38 (35%) did not sell syringes of the types used by IDUs; of these, half stocked but refused to sell syringes to research staff, and the other half did not stock syringes at all. Overall 70 (65%) of the pharmacies did sell syringes; of these, 49 pharmacies sold single syringes without any restrictions and 21 offered packages of ten. Conclusions Trainings for pharmacists need to be conducted to reduce negative attitudes towards IDUs and increase pharmacists’ willingness to sell syringes. At a structural level, access to safe injection supplies for IDUs could be increased by including syringes in the federal list of mandatory medical products sold by pharmacies. PMID:23452390

Population regulation in Gyrodactylus salaris - Atlantic salmon (Salmo salar L.) interactions: testing the paradigm.

PubMed

Ramírez, Raúl; Bakke, Tor A; Harris, Philip D

2015-07-25

Gyrodactylus salaris is a directly transmitted ectoparasite that reproduces in situ on its fish host. Wild Norwegian (East Atlantic) salmon stocks are thought to be especially susceptible to the parasite due to lack of co-adaptation, contrary to Baltic salmon stocks. This study i) identifies whether time- and density-dependent mechanisms in gyrodactylid population growth exist in G. salaris-Atlantic salmon interactions and ii) based on differences between Norwegian and Baltic stocks, determines whether the 'Atlantic susceptible, Baltic resistant' paradigm holds as an example of local adaptation. A total of 18 datasets of G. salaris population growth on individually isolated Atlantic salmon (12 different stocks) infected with three parasite strains were re-analysed using a Bayesian approach. Datasets included over 2000 observations of 388 individual fish. The best fitting model of population growth was time-limited; parasite population growth rate declined consistently from the beginning of infection. We found no evidence of exponential population growth in any dataset. In some stocks, a density dependence in the size of the initial inoculum limited the maximum rate of parasite population growth. There is no evidence to support the hypothesis that all Norwegian and Scottish Atlantic salmon stocks are equally susceptible to G. salaris, while Baltic stocks control and limit infections due to co-evolution. Northern and Western Norwegian as well as the Scottish Shin stocks, support higher initial parasite population growth rates than Baltic, South-eastern Norwegian, or the Scottish Conon stocks, and several Norwegian stocks tested (Akerselva, Altaelva, Lierelva, Numedalslågen), and the Scottish stocks (i.e. Conon, Shin), were able to limit infections after 40-50 days. No significant differences in performance of the three parasite strains (Batnfjordselva, Figga, and Lierelva), or the two parasite mitochondrial haplotypes (A and F) were observed. Our study shows a spectrum of growth rates, with some fish of the South-eastern Norwegian stocks sustaining parasite population growth rates overlapping those seen on Baltic Neva and Indalsälv stocks. This observation is inconsistent with the 'Baltic-resistant, Atlantic-susceptible' hypothesis, but suggests heterogeneity, perhaps linked to other host resistance genes driven by selection for local disease syndromes.

Subsoil carbon accumulation on an arable Mollisol is retention dominated, in contrast to input driven carbon dynamics in topsoil

NASA Astrophysics Data System (ADS)

Beem-Miller, Jeffrey; Lehmann, Johannes

2017-04-01

The majority of the world's soil organic carbon (OC) stock is stored below 30 cm in depth, yet sampling for soil OC assessment rarely goes below 30 cm. Recent studies suggest that subsoil OC is distinct from topsoil OC in quantity and quality: subsoil OC concentrations are typically much lower and turnover times are much longer, but the mechanisms involved in retention and input of OC to the subsoil are not well understood. Improving our understanding of subsoil OC is essential for balancing the global carbon budget and confronting the challenge of global climate change. This study was undertaken to assess the relationship between OC stock and potential drivers of OC dynamics, including both soil properties and environmental covariates, in topsoil (0 to 30 cm) versus subsoil (30 to 75 cm). The performance of commonly used depth functions in predicting OC stock from 0 to 75 cm was also assessed. Depth functions are a useful tool for extrapolating OC stock below the depth of sampling, but may poorly model "hot spots" of OC accumulation, and be inadequate for modelling the distinct dynamics of topsoil and subsoil OC when applied with a single functional form. We collected two hundred soil cores on an arable Mollisol, sectioned into five depth increments (0-10, 10-20, 20-30, 30-50, and 50-75 cm), and performed the following analyses on each depth increment: concentration of OC, inorganic C, permanganate oxidizable carbon (POXC), and total N, as well as texture, pH, and bulk density; a digital elevation model was used to calculate elevation, slope, curvature, and soil topographic wetness index. We found that topsoil OC stocks were significantly correlated (p < 0.05) with terrain variables, texture, and pH, while subsoil OC stock was only significantly correlated with topsoil OC stock and soil pH. Total OC stock was highly spatially variable, and the relationship between surface soil properties, terrain variables, and subsoil OC stock was spatially variable as well. Hot spots of subsoil OC accumulation were correlated with higher pH (> 7.0), flat topography, a high OC to total N ratio, and a high ratio of POXC to OC. These findings suggest that at this site, topsoil OC stock is input driven, while OC accumulation in the subsoil is retention dominated. Accordingly, a new depth function is proposed that uses a linear relationship to model OC stock in topsoil and a power function to model OC stock in the subsoil. The combined depth function performed better than did negative exponential, power, and linear functions alone.

Effects of human population density and proximity to markets on coral reef fishes vulnerable to extinction by fishing.

PubMed

Brewer, T D; Cinner, J E; Green, A; Pressey, R L

2013-06-01

Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life-history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing. © 2012 Society for Conservation Biology.

Spatial patterns of carbon, biodiversity, deforestation threat, and REDD+ projects in Indonesia.

PubMed

Murray, Josil P; Grenyer, Richard; Wunder, Sven; Raes, Niels; Jones, Julia P G

2015-10-01

There are concerns that Reduced Emissions from Deforestation and forest Degradation (REDD+) may fail to deliver potential biodiversity cobenefits if it is focused on high carbon areas. We explored the spatial overlaps between carbon stocks, biodiversity, projected deforestation threats, and the location of REDD+ projects in Indonesia, a tropical country at the forefront of REDD+ development. For biodiversity, we assembled data on the distribution of terrestrial vertebrates (ranges of amphibians, mammals, birds, reptiles) and plants (species distribution models for 8 families). We then investigated congruence between different measures of biodiversity richness and carbon stocks at the national and subnational scales. Finally, we mapped active REDD+ projects and investigated the carbon density and potential biodiversity richness and modeled deforestation pressures within these forests relative to protected areas and unprotected forests. There was little internal overlap among the different hotspots (richest 10% of cells) of species richness. There was also no consistent spatial congruence between carbon stocks and the biodiversity measures: a weak negative correlation at the national scale masked highly variable and nonlinear relationships island by island. Current REDD+ projects were preferentially located in areas with higher total species richness and threatened species richness but lower carbon densities than protected areas and unprotected forests. Although a quarter of the total area of these REDD+ projects is under relatively high deforestation pressure, the majority of the REDD+ area is not. In Indonesia at least, first-generation REDD+ projects are located where they are likely to deliver biodiversity benefits. However, if REDD+ is to deliver additional gains for climate and biodiversity, projects will need to focus on forests with the highest threat to deforestation, which will have cost implications for future REDD+ implementation. © 2015 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of Society for Conservation Biology.

Floor space covered by broiler chickens kept at stocking densities according to Council Directive 2007/43/EC.

PubMed

Giersberg, M F; Hartung, J; Kemper, N; Spindler, B

2016-07-30

It is controversially discussed whether the stocking densities set by the EU Directive 2007/43/EC allow a species-appropriate housing of broiler chickens. To calculate the exact area broilers occupy due to their physical size and shape, planimetric measurements using a colour-contrast method were carried out. In total, 1949 photographs of standing and 1482 of squatting chickens, taken from a top view, were analysed. A computer program counted the pixels representing the previously weighed animal in the photograph and calculated the animal area. The average area covered by chickens with 400 g live weight was 116.64±13.12 cm(2) in a standing and 138.61±12.92 cm(2) in a squatting position. These areas increased linearly as a function of live weight to 452.57±58.89 cm(2) (R(2)=0.90 standing) and 513.54±42.70 cm(2) (R(2)=0.82 squatting) at the end of the study (3200 g live weight). Squatting chickens occupied more space compared with a standing position in most of the tested weight classes (P<0.05). Depending on target weights, stocking densities and body positions, broilers occupied 48.5-77.7 per cent of 1 m(2) Thus, from a physical point of view, simultaneous resting is possible at any stocking density provided by the EU Directive and at common target weights. British Veterinary Association.

The association between price, competition, and demand factors on private sector anti-malarial stocking and sales in western Kenya: considerations for the AMFm subsidy.

PubMed

O'Meara, Wendy Prudhomme; Obala, Andrew; Thirumurthy, Harsha; Khwa-Otsyula, Barasa

2013-06-05

Households in sub-Saharan Africa are highly reliant on the retail sector for obtaining treatment for malaria fevers and other illnesses. As donors and governments seek to promote the use of artemisinin combination therapy in malaria-endemic areas through subsidized anti-malarials offered in the retail sector, understanding the stocking and pricing decisions of retail outlets is vital. A survey of all medicine retailers serving Bungoma East District in western Kenya was conducted three months after the launch of the AMFm subsidy in Kenya. The survey obtained information on each anti-malarial in stock: brand name, price, sales volume, outlet characteristics and GPS co-ordinates. These data were matched to household-level data from the Webuye Health and Demographic Surveillance System, from which population density and fever prevalence near each shop were determined. Regression analysis was used to identify the factors associated with retailers' likelihood of stocking subsidized artemether lumefantrine (AL) and the association between price and sales for AL, quinine and sulphadoxine-pyrimethamine (SP). Ninety-seven retail outlets in the study area were surveyed; 11% of outlets stocked subsidized AL. Size of the outlet and having a pharmacist on staff were associated with greater likelihood of stocking subsidized AL. In the multivariable model, total volume of anti-malarial sales was associated with greater likelihood of stocking subsidized AL and competition was important; likelihood of stocking subsidized AL was considerably higher if the nearest neighbour stocked subsidized AL. Price was a significant predictor of sales volume for all three types of anti-malarials but the relationship varied, with the largest price sensitivity found for SP drugs. The results suggest that helping small outlets overcome the constraints to stocking subsidized AL should be a priority. Competition between retailers and prices can play an important role in greater adoption of AL.

The association between price, competition, and demand factors on private sector anti-malarial stocking and sales in western Kenya: considerations for the AMFm subsidy

PubMed Central

2013-01-01

Background Households in sub-Saharan Africa are highly reliant on the retail sector for obtaining treatment for malaria fevers and other illnesses. As donors and governments seek to promote the use of artemisinin combination therapy in malaria-endemic areas through subsidized anti-malarials offered in the retail sector, understanding the stocking and pricing decisions of retail outlets is vital. Methods A survey of all medicine retailers serving Bungoma East District in western Kenya was conducted three months after the launch of the AMFm subsidy in Kenya. The survey obtained information on each anti-malarial in stock: brand name, price, sales volume, outlet characteristics and GPS co-ordinates. These data were matched to household-level data from the Webuye Health and Demographic Surveillance System, from which population density and fever prevalence near each shop were determined. Regression analysis was used to identify the factors associated with retailers’ likelihood of stocking subsidized artemether lumefantrine (AL) and the association between price and sales for AL, quinine and sulphadoxine-pyrimethamine (SP). Results Ninety-seven retail outlets in the study area were surveyed; 11% of outlets stocked subsidized AL. Size of the outlet and having a pharmacist on staff were associated with greater likelihood of stocking subsidized AL. In the multivariable model, total volume of anti-malarial sales was associated with greater likelihood of stocking subsidized AL and competition was important; likelihood of stocking subsidized AL was considerably higher if the nearest neighbour stocked subsidized AL. Price was a significant predictor of sales volume for all three types of anti-malarials but the relationship varied, with the largest price sensitivity found for SP drugs. Conclusion The results suggest that helping small outlets overcome the constraints to stocking subsidized AL should be a priority. Competition between retailers and prices can play an important role in greater adoption of AL. PMID:23738604

Production of High Density Aviation Fuels via Novel Zeolite Catalyst Routes

DTIC Science & Technology

1989-10-23

range fraction of a naphthenic crude; saturation of an aromatic FCC cycle stock I the appropriate boiling range: saturation of an appropriate boiling...aromatic hydrocarbons and selected aromatic feedstocks to the corresponding mono- and dicyclic naphthenes in the aviation turbine fuel boiling range; and...Paraffins from Naphthenic Refinery Feed Streams .......... 8 Solvent Extraction ........................................... 8 Shape Selective Catalytic

The effects of regional angling effort, angler behavior, and harvesting efficiency on landscape patterns of overfishing.

PubMed

Hunt, Len M; Arlinghaus, Robert; Lester, Nigel; Kushneriuk, Rob

2011-10-01

We used a coupled social-ecological model to study the landscape-scale patterns emerging from a mobile population of anglers exploiting a spatially structured walleye (Sander vitreus) fishery. We systematically examined how variations in angler behaviors (i.e., relative importance of walleye catch rate in guiding fishing site choices), harvesting efficiency (as implied by varying degrees of inverse density-dependent catchability of walleye), and angler population size affected the depletion of walleye stocks across 157 lakes located near Thunder Bay (Ontario, Canada). Walleye production biology was calibrated using lake-specific morphometric and edaphic features, and angler fishing site choices were modeled using an empirically grounded multi-attribute utility function. We found support for the hypothesis of sequential collapses of walleye stocks across the landscape in inverse proportionality of travel cost from the urban residence of anglers. This pattern was less pronounced when the regional angler population was low, density-dependent catchability was absent or low, and angler choices of lakes in the landscape were strongly determined by catch rather than non-catch-related attributes. Thus, our study revealed a systematic pattern of high catch importance reducing overfishing potential at low and aggravating overfishing potential at high angler population sizes. The analyses also suggested that density-dependent catchability might have more serious consequences for regional overfishing states than variations in angler behavior. We found little support for the hypotheses of systematic overexploitation of the most productive walleye stocks and homogenized catch-related qualities among lakes sharing similar access costs to anglers. Therefore, one should not expect anglers to systematically exploit the most productive fisheries or to equalize catch rates among lakes through their mobility and other behaviors. This study underscores that understanding landscape overfishing dynamics involves a careful appreciation of angler population size and how it interacts with the attributes that drive angler behaviors and depensatory mechanisms such as inverse density-dependent catchability. Only when all of these ingredients are considered and understood can one derive reasonably predictable patterns of overfishing in the landscape. These patterns range from self-regulating systems with low levels of regional fishing pressure to sequential collapse of walleye fisheries from the origin of angling effort.

Charting Availability of Processed and Unprocessed Foods in School Neighbourhood Nutrition Environments in an Urban Australian Setting

PubMed Central

Oaken, Holly; Vaughan, Lisa; Fa'avale, Nicola

2017-01-01

School Neighbourhood Nutrition Environments (SNNEs) can facilitate or impede healthy eating. This study describes the SNNEs surrounding 6 Good Start Program (GSP) schools in 5 suburbs in Logan, Queensland. Relative density of healthy and unhealthy food outlets was calculated for SNNEs surrounding GSP (6) and non-GSP (10) schools within the 5 suburbs. Relative accessibility of minimally processed and highly processed food and drink in SNNEs of the 6 GSP schools was determined using shelf measurements of snack foods. Unhealthy outlets greatly outnumber healthy outlets (mean relative density 15.6%, median 19.1%). The majority of outlets stock predominantly highly processed food and drink. Study areas are dominated by unhealthy food outlets and highly processed food. PMID:28553361

Accounting for density reduction and structural loss in standing dead trees: Implications for forest biomass and carbon stock estimates in the United States

Treesearch

Grant M. Domke; Christopher W. Woodall; James E. Smith

2011-01-01

Standing dead trees are one component of forest ecosystem dead wood carbon (C) pools, whose national stock is estimated by the U.S. as required by the United Nations Framework Convention on Climate Change. Historically, standing dead tree C has been estimated as a function of live tree growing stock volume in the U.S.'s National Greenhouse Gas Inventory. Initiated...

Local overfishing may be avoided by examining parameters of a spatio-temporal model

PubMed Central

Shackell, Nancy; Mills Flemming, Joanna

2017-01-01

Spatial erosion of stock structure through local overfishing can lead to stock collapse because fish often prefer certain locations, and fisheries tend to focus on those locations. Fishery managers are challenged to maintain the integrity of the entire stock and require scientific approaches that provide them with sound advice. Here we propose a Bayesian hierarchical spatio-temporal modelling framework for fish abundance data to estimate key parameters that define spatial stock structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). The consideration of these spatial parameters in the stock assessment process can help identify the erosion of structure and assist in preventing local overfishing. We use Atlantic cod (Gadus morhua) in eastern Canada as a case study an examine the behaviour of these parameters from the height of the fishery through its collapse. We identify clear signals in parameter behaviour under circumstances of destructive stock erosion as well as for recovery of spatial structure even when combined with a non-recovery in abundance. Further, our model reveals the spatial pattern of areas of high and low density persists over the 41 years of available data and identifies the remnant patches. Models of this sort are crucial to recovery plans if we are to identify and protect remaining sources of recolonization for Atlantic cod. Our method is immediately applicable to other exploited species. PMID:28886179

Local overfishing may be avoided by examining parameters of a spatio-temporal model.

PubMed

Carson, Stuart; Shackell, Nancy; Mills Flemming, Joanna

2017-01-01

Spatial erosion of stock structure through local overfishing can lead to stock collapse because fish often prefer certain locations, and fisheries tend to focus on those locations. Fishery managers are challenged to maintain the integrity of the entire stock and require scientific approaches that provide them with sound advice. Here we propose a Bayesian hierarchical spatio-temporal modelling framework for fish abundance data to estimate key parameters that define spatial stock structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). The consideration of these spatial parameters in the stock assessment process can help identify the erosion of structure and assist in preventing local overfishing. We use Atlantic cod (Gadus morhua) in eastern Canada as a case study an examine the behaviour of these parameters from the height of the fishery through its collapse. We identify clear signals in parameter behaviour under circumstances of destructive stock erosion as well as for recovery of spatial structure even when combined with a non-recovery in abundance. Further, our model reveals the spatial pattern of areas of high and low density persists over the 41 years of available data and identifies the remnant patches. Models of this sort are crucial to recovery plans if we are to identify and protect remaining sources of recolonization for Atlantic cod. Our method is immediately applicable to other exploited species.

Destiny-yield relationship for channel catfish reared in a biofloc technology production system

USDA-ARS?s Scientific Manuscript database

The effect of stocking density on yield of stocker channel catfish and water quality in a biofloc technology production system was studied in this completely randomized design experiment. Fingerling channel catfish (Ictalurus punctatus; 48.0 g/fish, 17.8 cm/fish) were stocked into nine continuously ...

Ecosystem carbon stocks in Pinus palustris forests

Treesearch

Lisa Samuelson; Tom Stokes; John R. Butnor; Kurt H. Johnsen; Carlos A. Gonzalez-Benecke; Pete Anderson; Jason Jackson; Lorenzo Ferrari; Tim A. Martin; Wendell P. Cropper

2014-01-01

Longleaf pine (Pinus palustris Mill.) restoration in the southeastern United States offers opportunities for carbon (C) sequestration. Ecosystem C stocks are not well understood in longleaf pine forests, which are typically of low density and maintained by prescribed fire. The objectives of this research were to develop allometric equations for...

Global distribution of soil organic carbon - Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world

NASA Astrophysics Data System (ADS)

Köchy, M.; Hiederer, R.; Freibauer, A.

2015-04-01

The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg when using the original values for bulk density. Adjusting the HWSD's bulk density (BD) of soil high in organic carbon results in a mass of 1230 Pg, and additionally setting the BD of Histosols to 0.1 g cm-3 (typical of peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols alone introduces a range of -56 to +180 Pg C into the estimate of global SOC mass in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. With more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils, whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

Repeated prescribed fires decrease stocks and change attributes of coarse woody debris in a temperate eucalypt forest.

PubMed

Aponte, Cristina; Tolhurst, Kevin G; Bennett, Lauren T

2014-07-01

Previous studies have found negligible effects of single prescribed fires on coarse woody debris (CWD), but the cumulative effects of repeated low-intensity prescribed fires are unknown. This represents a knowledge gap for environmental management because repeated prescribed fires are a key tool for mitigating wildfire risk, and because CWD is recognized as critical to forest biodiversity and functioning. We examined the effects of repeated low-intensity prescribed fires on the attributes and stocks of (fallen) CWD in a mixed-species eucalypt forest of temperate Australia. Prescribed fire treatments were a factorial combination of two seasons (Autumn, Spring) and two frequencies (three yearly High, 10 yearly Low), were replicated over five study areas, and involved two to seven low-intensity fires over 27 years. Charring due to prescribed fires variously changed carbon and nitrogen concentrations and C to N ratios of CWD pieces depending on decay class, but did not affect mean wood density. CWD biomass and C and N stocks were significantly less in Fire than Control treatments. Decreases in total CWD C stocks of -8 Mg/ha in Fire treatments were not balanced by minor increases in pyrogenic (char) C (-0.3 Mg/ha). Effects of prescribed fire frequency and season included significantly less C and N stocks in rotten CWD in High than Low frequency treatments, and in the largest CWD pieces in Autumn than Spring treatments. Our study demonstrates that repeated low-intensity prescribed fires have the potential to significantly decrease CWD stocks, in pieces of all sizes and particularly decayed pieces, and to change CWD chemical attributes. CWD is at best a minor stock of pyrogenic C under such fire regimes. These findings suggest a potential trade-off in the management of temperate eucalypt forests between sustained reduction of wildfire risk, and the consequences of decreased CWD C stocks, and of changes in CWD as a habitat and biogeochemical substrate. Nonetheless, negative impacts on CWD of repeated low-intensity prescribed fires could be lessened by fire intervals of 10 rather than three years (to decrease losses of decayed CWD), and fires in moist rather than dry conditions (to conserve large CWD).

Airborne Lidar-Based Estimates of Tropical Forest Structure in Complex Terrain: Opportunities and Trade-Offs for REDD+

NASA Technical Reports Server (NTRS)

Leitold, Veronika; Keller, Michael; Morton, Douglas C.; Cook, Bruce D.; Shimabukuro, Yosio E.

2015-01-01

Background: Carbon stocks and fluxes in tropical forests remain large sources of uncertainty in the global carbon budget. Airborne lidar remote sensing is a powerful tool for estimating aboveground biomass, provided that lidar measurements penetrate dense forest vegetation to generate accurate estimates of surface topography and canopy heights. Tropical forest areas with complex topography present a challenge for lidar remote sensing. Results: We compared digital terrain models (DTM) derived from airborne lidar data from a mountainous region of the Atlantic Forest in Brazil to 35 ground control points measured with survey grade GNSS receivers. The terrain model generated from full-density (approx. 20 returns/sq m) data was highly accurate (mean signed error of 0.19 +/-0.97 m), while those derived from reduced-density datasets (8/sq m, 4/sq m, 2/sq m and 1/sq m) were increasingly less accurate. Canopy heights calculated from reduced-density lidar data declined as data density decreased due to the inability to accurately model the terrain surface. For lidar return densities below 4/sq m, the bias in height estimates translated into errors of 80-125 Mg/ha in predicted aboveground biomass. Conclusions: Given the growing emphasis on the use of airborne lidar for forest management, carbon monitoring, and conservation efforts, the results of this study highlight the importance of careful survey planning and consistent sampling for accurate quantification of aboveground biomass stocks and dynamics. Approaches that rely primarily on canopy height to estimate aboveground biomass are sensitive to DTM errors from variability in lidar sampling density.

Airborne lidar-based estimates of tropical forest structure in complex terrain: opportunities and trade-offs for REDD+

PubMed

Leitold, Veronika; Keller, Michael; Morton, Douglas C; Cook, Bruce D; Shimabukuro, Yosio E

2015-12-01

Carbon stocks and fluxes in tropical forests remain large sources of uncertainty in the global carbon budget. Airborne lidar remote sensing is a powerful tool for estimating aboveground biomass, provided that lidar measurements penetrate dense forest vegetation to generate accurate estimates of surface topography and canopy heights. Tropical forest areas with complex topography present a challenge for lidar remote sensing. We compared digital terrain models (DTM) derived from airborne lidar data from a mountainous region of the Atlantic Forest in Brazil to 35 ground control points measured with survey grade GNSS receivers. The terrain model generated from full-density (~20 returns m -2 ) data was highly accurate (mean signed error of 0.19 ± 0.97 m), while those derived from reduced-density datasets (8 m -2 , 4 m -2 , 2 m -2 and 1 m -2 ) were increasingly less accurate. Canopy heights calculated from reduced-density lidar data declined as data density decreased due to the inability to accurately model the terrain surface. For lidar return densities below 4 m -2 , the bias in height estimates translated into errors of 80-125 Mg ha -1 in predicted aboveground biomass. Given the growing emphasis on the use of airborne lidar for forest management, carbon monitoring, and conservation efforts, the results of this study highlight the importance of careful survey planning and consistent sampling for accurate quantification of aboveground biomass stocks and dynamics. Approaches that rely primarily on canopy height to estimate aboveground biomass are sensitive to DTM errors from variability in lidar sampling density.

76 FR 38715 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-01

... of a pair of power receptacles (60 amps 208 volts), which would provide enough power for a high density cabinet. The proposed fee for installation of the pair of the 60-amp 208-volt power receptacles is... Exchange to earn a profit. In the case of the proposed fees for a pair of the 60-amp power receptacles and...

Seasonal Changes in Adult Longevity and Pupal Weight of the Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) with Implications for Interpreting Pheromone Trap Catch

Treesearch

Christopher Asaro; C. Wayne Berisford

2001-01-01

Pheromone trap catches of the Nantucket pine tip moth, Rhyacionia frustrana (Corn-stock), are often much higher during the first generation as compared with later generations, regardless of population density or damage levels. One hypothesis proposed to explain this phenomenon is reduced adult longevity during summer due to high temperatures. In this...

A GIS-based tool for estimating tree canopy cover on fixed-radius plots using high-resolution aerial imagery

Treesearch

Sara A. Goeking; Greg C. Liknes; Erik Lindblom; John Chase; Dennis M. Jacobs; Robert. Benton

2012-01-01

Recent changes to the Forest Inventory and Analysis (FIA) Program's definition of forest land precipitated the development of a geographic information system (GIS)-based tool for efficiently estimating tree canopy cover for all FIA plots. The FIA definition of forest land has shifted from a density-related criterion based on stocking to a 10 percent tree canopy...

When is pin cherry (Prunus pensylvanica L.) a problem in Allegheny hardwoods?

Treesearch

Todd E. Ristau; Stephen B. Horsley

2006-01-01

Pin cherry (Prunus pensylvanica L.) has important effects on early stand development when it occurs at high densities. We used data describing the first 15 years of stand development in eight clearcuts and used plots that had at least 25 black cherry or 100 desirable seedlings at age 3, as well as different levels of pin cherry stocking. Our findings...

Status of lake trout rehabilitation in the Northern Refuge of Lake Michigan

USGS Publications Warehouse

Madenjian, Charles P.; DeSorcie, Timothy J.

1999-01-01

The Northern Refuge in Lake Michigan was established in 1985 as part of a rehabilitation program to stock yearling lake trout Salvelinus namaycush in areas with the best potential for success. Stocking of hatchery-reared lake trout within the refuge began in 1986 at three reefs: Boulder Reef, Gull Island Reef, and Richards Reef. On each reef from 1991 to 1997 we conducted gill-net surveys during the fall spawning season to evaluate performance of adult lake trout, and we conducted beam trawl surveys for naturally reproduced age-0 lake trout in the spring. Criteria to evaluate performance included spawner density, growth, maturity, and mortality. We found no evidence of natural reproduction by lake trout from our surveys. Nevertheless, density of spawning lake trout on Boulder Reef (69 fish/305 m of gill net/night) and Gull Island Reef (34 fish/305 m of gill net/night) appeared to be sufficiently high to initiate a self-sustaining population. Growth and maturity rates of lake trout in the Northern Refuge were similar to those for lake trout stocked in the nearshore region of Lake Michigan. In the Northern Refuge, growth rate for the Marquette strain of lake trout was slightly higher than for the Lewis Lake strain. Annual mortality estimates from catch curve analyses ranged from 0.46 to 0.41, and therefore, these estimates approached a level that was considered to be sufficiently low to allow for a self-sustaining population. Thus, it appeared that the lack of evidence for natural reproduction by lake trout in the Northern Refuge should not be attributed to inability of the population to attain a sufficiently large stock of spawners.

Using Grizzly Bears to Assess Harvest-Ecosystem Tradeoffs in Salmon Fisheries

PubMed Central

MacDuffee, Misty; Mangel, Marc; Paquet, Paul; Wilmers, Christopher C.

2012-01-01

Implementation of ecosystem-based fisheries management (EBFM) requires a clear conceptual and quantitative framework for assessing how different harvest options can modify benefits to ecosystem and human beneficiaries. We address this social-ecological need for Pacific salmon fisheries, which are economically valuable but intercept much of the annual pulse of nutrient subsidies that salmon provide to terrestrial and aquatic food webs. We used grizzly bears, vectors of salmon nutrients and animals with densities strongly coupled to salmon abundance, as surrogates for “salmon ecosystem” function. Combining salmon biomass and stock-recruitment data with stable isotope analysis, we assess potential tradeoffs between fishery yields and bear population densities for six sockeye salmon stocks in Bristol Bay, Alaska, and British Columbia (BC), Canada. For the coastal stocks, we find that both bear densities and fishery yields would increase substantially if ecosystem allocations of salmon increase from currently applied lower to upper goals and beyond. This aligning of benefits comes at a potential cost, however, with the possibility of forgoing harvests in low productivity years. In contrast, we detect acute tradeoffs between bear densities and fishery yields in interior stocks within the Fraser River, BC, where biomass from other salmon species is low. There, increasing salmon allocations to ecosystems would benefit threatened bear populations at the cost of reduced long-term yields. To resolve this conflict, we propose an EBFM goal that values fisheries and bears (and by extension, the ecosystem) equally. At such targets, ecosystem benefits are unexpectedly large compared with losses in fishery yields. To explore other management options, we generate tradeoff curves that provide stock-specific accounting of the expected loss to fishers and gain to bears as more salmon escape the fishery. Our approach, modified to suit multiple scenarios, provides a generalizable method to resolve conflicts over shared resources in other systems. PMID:22505845

Using grizzly bears to assess harvest-ecosystem tradeoffs in salmon fisheries.

PubMed

Levi, Taal; Darimont, Chris T; Macduffee, Misty; Mangel, Marc; Paquet, Paul; Wilmers, Christopher C

2012-01-01

Implementation of ecosystem-based fisheries management (EBFM) requires a clear conceptual and quantitative framework for assessing how different harvest options can modify benefits to ecosystem and human beneficiaries. We address this social-ecological need for Pacific salmon fisheries, which are economically valuable but intercept much of the annual pulse of nutrient subsidies that salmon provide to terrestrial and aquatic food webs. We used grizzly bears, vectors of salmon nutrients and animals with densities strongly coupled to salmon abundance, as surrogates for "salmon ecosystem" function. Combining salmon biomass and stock-recruitment data with stable isotope analysis, we assess potential tradeoffs between fishery yields and bear population densities for six sockeye salmon stocks in Bristol Bay, Alaska, and British Columbia (BC), Canada. For the coastal stocks, we find that both bear densities and fishery yields would increase substantially if ecosystem allocations of salmon increase from currently applied lower to upper goals and beyond. This aligning of benefits comes at a potential cost, however, with the possibility of forgoing harvests in low productivity years. In contrast, we detect acute tradeoffs between bear densities and fishery yields in interior stocks within the Fraser River, BC, where biomass from other salmon species is low. There, increasing salmon allocations to ecosystems would benefit threatened bear populations at the cost of reduced long-term yields. To resolve this conflict, we propose an EBFM goal that values fisheries and bears (and by extension, the ecosystem) equally. At such targets, ecosystem benefits are unexpectedly large compared with losses in fishery yields. To explore other management options, we generate tradeoff curves that provide stock-specific accounting of the expected loss to fishers and gain to bears as more salmon escape the fishery. Our approach, modified to suit multiple scenarios, provides a generalizable method to resolve conflicts over shared resources in other systems.

High-density fiber optic biosensor arrays

NASA Astrophysics Data System (ADS)

Epstein, Jason R.; Walt, David R.

2002-02-01

Novel approaches are required to coordinate the immense amounts of information derived from diverse genomes. This concept has influenced the expanded role of high-throughput DNA detection and analysis in the biological sciences. A high-density fiber optic DNA biosensor was developed consisting of oligonucleotide-functionalized, 3.1 mm diameter microspheres deposited into the etched wells on the distal face of a 500 micrometers imaging fiber bundle. Imaging fiber bundles containing thousands of optical fibers, each associated with a unique oligonucleotide probe sequence, were the foundation for an optically connected, individually addressable DNA detection platform. Different oligonucleotide-functionalized microspheres were combined in a stock solution, and randomly dispersed into the etched wells. Microsphere positions were registered from optical dyes incorporated onto the microspheres. The distribution process provided an inherent redundancy that increases the signal-to-noise ratio as the square root of the number of sensors examined. The representative amount of each probe-type in the array was dependent on their initial stock solution concentration, and as other sequences of interest arise, new microsphere elements can be added to arrays without altering the existing detection capabilities. The oligonucleotide probe sequences hybridize to fluorescently-labeled, complementary DNA target solutions. Fiber optic DNA microarray research has included DNA-protein interaction profiles, microbial strain differentiation, non-labeled target interrogation with molecular beacons, and single cell-based assays. This biosensor array is proficient in DNA detection linked to specific disease states, single nucleotide polymorphism (SNP's) discrimination, and gene expression analysis. This array platform permits multiple detection formats, provides smaller feature sizes, and enables sensor design flexibility. High-density fiber optic microarray biosensors provide a fast, reversible format with the detection limit of a few hundred molecules.

Synergies between climate and management for Atlantic cod fisheries at high latitudes

PubMed Central

Kjesbu, Olav Sigurd; Bogstad, Bjarte; Devine, Jennifer A.; Gjøsæter, Harald; Howell, Daniel; Ingvaldsen, Randi B.; Nash, Richard D. M.; Skjæraasen, Jon Egil

2014-01-01

The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and positive changes in population size, this invariably leads to questions about whether favorable climatic conditions or good management (or both) were responsible. The Barents Sea cod (Gadus morhua) stock has recently increased markedly and the spawning stock biomass is now at an unprecedented high. We identify the crucial social and environmental factors that made this unique growth possible. The relationship between vital rates of Barents Sea cod stock productivity (recruitment, growth, and mortality) and environment is investigated, followed by simulations of population size under different management scenarios. We show that the recent sustained reduction in fishing mortality, facilitated by the implementation of a “harvest control rule,” was essential to the increase in population size. Simulations show that a drastic reduction in fishing mortality has resulted in a doubling of the total population biomass compared with that expected under the former management regime. However, management alone was not solely responsible. We document that prevailing climate, operating through several mechanistic links, positively reinforced management actions. Heightened temperature resulted in an increase in the extent of the suitable feeding area for Barents Sea cod, likely offering a release from density-dependent effects (for example, food competition and cannibalism) through prolonged overlap with prey and improved adult stock productivity. Management and climate may thus interact to give a positive outlook for exploited high-latitude marine resources. PMID:24550465

Synergies between climate and management for Atlantic cod fisheries at high latitudes.

PubMed

Kjesbu, Olav Sigurd; Bogstad, Bjarte; Devine, Jennifer A; Gjøsæter, Harald; Howell, Daniel; Ingvaldsen, Randi B; Nash, Richard D M; Skjæraasen, Jon Egil

2014-03-04

The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and positive changes in population size, this invariably leads to questions about whether favorable climatic conditions or good management (or both) were responsible. The Barents Sea cod (Gadus morhua) stock has recently increased markedly and the spawning stock biomass is now at an unprecedented high. We identify the crucial social and environmental factors that made this unique growth possible. The relationship between vital rates of Barents Sea cod stock productivity (recruitment, growth, and mortality) and environment is investigated, followed by simulations of population size under different management scenarios. We show that the recent sustained reduction in fishing mortality, facilitated by the implementation of a "harvest control rule," was essential to the increase in population size. Simulations show that a drastic reduction in fishing mortality has resulted in a doubling of the total population biomass compared with that expected under the former management regime. However, management alone was not solely responsible. We document that prevailing climate, operating through several mechanistic links, positively reinforced management actions. Heightened temperature resulted in an increase in the extent of the suitable feeding area for Barents Sea cod, likely offering a release from density-dependent effects (for example, food competition and cannibalism) through prolonged overlap with prey and improved adult stock productivity. Management and climate may thus interact to give a positive outlook for exploited high-latitude marine resources.

Mapping High Biomass Corridors for Climate and Biodiversity Co-Benefits

NASA Astrophysics Data System (ADS)

Jantz, P.; Goetz, S. J.; Laporte, N. T.

2013-12-01

A key issue in global conservation is how climate mitigation activities can secure biodiversity co-benefits. Tropical deforestation releases significant amounts of CO2 to the atmosphere and results in widespread biodiversity loss. The dominant strategy for forest conservation has been protected area designation. However, maintaining biodiversity in protected areas requires ecological exchange with ecosystems in which they are embedded. At current funding levels, existing conservation strategies are unlikely to prevent further loss of connectivity between protected areas and surrounding landscapes. The emergence of REDD+, a mechanism for funding carbon emissions reductions from deforestation in developing countries, suggests an alignment of goals and financial resources for protecting forest carbon, maintaining biodiversity in protected areas, and minimizing loss of forest ecosystem services. Identifying, protecting and sustainably managing vegetation carbon stocks between protected areas can provide both climate mitigation benefits through avoided CO2 emissions from deforestation and biodiversity benefits through the targeted protection of forests that maintain connectivity between protected areas and surrounding ecosystems. We used a high resolution, pan-tropical map of vegetation carbon stocks derived from MODIS, GLAS lidar and field measurements to map corridors that traverse areas of highest aboveground biomass between protected areas. We mapped over 13,000 corridors containing 49 GtC, accounting for 14% of unprotected vegetation carbon stock in the tropics. In the majority of cases, carbon density in corridors was commensurate with that of the protected areas they connect, suggesting significant opportunities for achieving climate mitigation and biodiversity co-benefits. To further illustrate the utility of this approach, we conducted a multi-criteria analysis of corridors in the Brazilian Amazon, identifying high biodiversity, high vegetation carbon stock corridors with low opportunity costs which may be good candidates for inclusion in climate mitigation activities like those being considered under REDD+.

Environmental Assessment: Lake Yankton Fish Population Renovation Project Yankton County, South Dakota and Cedar County, Nebraska

DTIC Science & Technology

2014-08-01

2013 for largemouth bass only. Year Largemouth bass CPUE1 (Total no/hr) PSD2 RSD -P3 1994 61 80 43 1995 61 49 9 1996 84 57 17 1997 59 95 15 1998...of 50-80 for bass is desirable for a pond manager with trophy bass goals. 3 RSD (relative stock density) - The relative stock density is the...percentage of fish of any designated length-group in a sample of fish. Within that sample the RSD -P is the percentage of those fish that are of preferred

Low intensity, mixed livestock grazing improves the breeding abundance of a common insectivorous passerine.

PubMed

Evans, Darren M; Redpath, Stephen M; Evans, Sharon A; Elston, David A; Gardner, Charles J; Dennis, Peter; Pakeman, Robin J

2006-12-22

Livestock grazing is a major driver of ecosystem change and has been associated with significant declines in various bird species in Britain and worldwide. However, there is little experimental evidence to show how grazing affects bird populations. We manipulated livestock densities in a replicated field experiment and found that mixed sheep and cattle grazing, at low intensity, improved the breeding abundance of a common upland passerine, the meadow pipit Anthus pratensis, after two years. Plots stocked with sheep alone (at high or low density) or not stocked at all held fewer pipit territories. Despite a year-on-year decline in pairs of meadow pipits in intensively grazed plots, we found no effect of sheep number on breeding abundance. Our results support the hypothesis that mixed species of herbivores generate greater heterogeneity in vegetation structure, which modifies prey availability, resulting in a greater abundance of birds. The results of our study should inform the management of grassland areas and enhance the abundance of some bird species, particularly in areas that have seen significant shifts from mixed livestock grazing to grazing dominated by single species of animals.

Bioeconomic modeling for a small-scale sea cucumber fishery in Yucatan, Mexico

PubMed Central

Hernández-Flores, Alvaro; Cuevas-Jiménez, Alfonso; Condal, Alfonso; Espinoza-Méndez, Juan Carlos

2018-01-01

Due to the heavy exploitation of holothurians over the last few decades, it is necessary to implement fishing regulations aimed at reversing this situation. Holothurians require specific regulations that take into account their biology and ecology. Their behavior to group and form patches as a strategy for feeding, defense and reproduction, makes them vulnerable to overfishing. The higher the population density, the higher the catchability coefficient, and because they are sedentary organisms, the catchability does not change significantly until the density is very low. Hence, the stock assessment of holothurians can be improved by analyzing their spatial distribution. This paper proposes a stock assessment technique that considers the spatial distribution pattern of the sea cucumber Isostichopus badionotus from Yucatan, Mexico. A bioeconomic spatial model was developed to explain the interactions between fishing effort allocation, quasi-profits and the population in the short term. Because of the high price of the species and the low production costs, artisanal fishers preferred to maximize short-term quasi-profits, rather than the long-term benefits they could gain with low fishing mortality rates. PMID:29315339

Bioeconomic modeling for a small-scale sea cucumber fishery in Yucatan, Mexico.

PubMed

Hernández-Flores, Alvaro; Cuevas-Jiménez, Alfonso; Poot-Salazar, Alicia; Condal, Alfonso; Espinoza-Méndez, Juan Carlos

2018-01-01

Due to the heavy exploitation of holothurians over the last few decades, it is necessary to implement fishing regulations aimed at reversing this situation. Holothurians require specific regulations that take into account their biology and ecology. Their behavior to group and form patches as a strategy for feeding, defense and reproduction, makes them vulnerable to overfishing. The higher the population density, the higher the catchability coefficient, and because they are sedentary organisms, the catchability does not change significantly until the density is very low. Hence, the stock assessment of holothurians can be improved by analyzing their spatial distribution. This paper proposes a stock assessment technique that considers the spatial distribution pattern of the sea cucumber Isostichopus badionotus from Yucatan, Mexico. A bioeconomic spatial model was developed to explain the interactions between fishing effort allocation, quasi-profits and the population in the short term. Because of the high price of the species and the low production costs, artisanal fishers preferred to maximize short-term quasi-profits, rather than the long-term benefits they could gain with low fishing mortality rates.

Turnover and storage of soil organic carbon from different land uses on an elevation gradient in the Peruvian Andes

NASA Astrophysics Data System (ADS)

Oliver, Viktoria; Kala, Jose; Lever, Rebecca; Oliveras, Imma; Arn Teh, Yit

2015-04-01

Tropical soils account for a third of global soil C and play a critical role in regulating atmospheric CO2 concentrations. The continuing fast rates of deforestation in the tropics for agricultural expansion and subsequent abandonment of new land uses are of particular interest to the science of soil C because of the associated C losses and potential for C sequestration. This study seeks to improve understanding of soil C stock changes within managed land in different ecosystems over a 2600 m gradient in the south-eastern Peruvian Andes. Using a density fractionation technique and natural abundance isotopes, the effects of the diverse range of local land use changes on 23 sites were investigated: grazing and burning on high altitude montane grasslands; burning in montane cloud forests; agricultural practices (cultivated and abandoned banana plantations, pastures of different grazing intensity), selective logging and secondary forest succession in the premontane forests. Overall, the montane grasslands and montane cloud forest had very similar soil C stocks down to 30 cm (167 ± 12 and 162 ± 36 Mg C ha-1), with the premontane forest containing approximately 35 % less soil C (61 ± 2.5 Mg C ha-1). The majority of the soil C pool (75 %) was recovered in the mineral - associated density fraction, with the montane grasslands containing on average ~ 10 % less C in this fraction than the premontane soils. Burning and grazing in the montane grasslands had no significant influence on the total C stocks but the distribution of physical density fractions were altered, with significantly lower labile fractions and burning alone causing higher occluded LFs. Burning in the upper montane forest had no significant effect on soil C stocks, except on one of the sites, which may have been a result of burning intensity or site-specific micro climate differences. Agricultural practices in the premontane elevation showed variable results in both total soil C and its distribution within the soil. Pineapple plantations had no effect on total soil C but significant losses in the free LF. Cultivated banana soils had significant total C losses (16.3 ± 0.5 Mg C ha-1), with the majority coming from the stable heavy F. The recovery of soil C was notable on an abandoned banana plantation of eight years due to the input of more recalcitrant material with forest regrowth and the same was found with the secondary forest. The total soil C stocks in the pasture soils were directly linked to the proportion of forest and grass derived C in the soil, with pasture sites containing the most forest derived C showing similar total C stocks to the mature forest. The data from this study show that the ability of the soils to maintain SOC stocks during land use changes are largely impacted by the physical distribution of C in the soil, the origin of C and dependent on type of land use.

Structural stocking guides: a new look at an old friend

Treesearch

Jeffrey H. Gove

2004-01-01

A parameter recovery-based model is developed that allows the incorporation of diameter distribution information directly into stocking guides. The method is completely general in applicability across different guides and forest types and could be adapted to other systems such as density management diagrams. It relies on a simple measure of diameter distribution shape...

Applications of statistical and atomic physics to the spectral line broadening and stock markets

NASA Astrophysics Data System (ADS)

Volodko, Dmitriy

The purpose of this investigation is the application of time correlation function methodology on the theoretical research of the shift of hydrogen and hydrogen-like spectral lines due to electrons and ions interaction with the spectral line emitters-dipole ionic-electronic shift (DIES) and the describing a behavior of stock-market in terms of a simple physical model simulation which obeys Levy statistical distribution---the same as that of the real stock-market index. Using Generalized Theory of Stark broadening of electrons in plasma we discovered a new source of the shift of hydrogen and hydrogen-like spectral lines that we called a dipole ionic-electronic shift (DIES). This shift results from the indirect coupling of electron and ion microfields in plasmas which is facilitated by the radiating atom/ion. We have shown that the DIES, unlike all previously known shifts, is highly nonlinear and has a different sign for different ranges of plasma parameters. The most favorable conditions for observing the DIES correspond to plasmas of high densities, but of relatively low temperature. For the Balmer-alpha line of hydrogen with the most favorable observational conditions Ne > 1018 cm-3, T < 2 eV, the DIES has been already confirmed experimentally. Based on the study of the time correlations and of the probability distribution of fluctuations in the stock market, we developed a relatively simple physical model, which simulates the Dow Jones Industrials index and makes short-term (a couple of days) predictions of its trend.

First record of Aedes (Stegomyia) albopictus in Belgium.

PubMed

Schaffner, Francis; Van Bortel, Wim; Coosemans, Marc

2004-06-01

The 1st record of Aedes albopictus in Belgium was made in a village in Oost-Vlaanderen Province. Two preimaginal stages were collected on October 31, 2000, in the used tire stock of a recycling company that imports tires from the USA and Japan. The species has reproduced on site, and local environmental conditions make its establishment possible. Anopheles plumbeus was a common companion species found in tires in high densities.

Influence of Honey Bee Genotype and Wintering Method on Wintering Performance of Varroa destructor (Parasitiformes: Varroidae)-Infected Honey Bee (Hymenoptera: Apidae) Colonies in a Northern Climate.

PubMed

Bahreini, Rassol; Currie, Robert W

2015-08-01

The objective of this study was to assess the effectiveness of a cooperative breeding program designed to enhance winter survival of honey bees (Apis mellifera L.) when exposed to high levels of varroa (Varroa destructor Anderson and Trueman) in outdoor-wintered and indoor-wintered colonies. Half of the colonies from selected and unselected stocks were randomly assigned to be treated with late autumn oxalic acid treatment or to be left untreated. Colonies were then randomly assigned to be wintered either indoors (n = 37) or outdoors (n = 40). Late autumn treatment with oxalic acid did not improve wintering performance. However, genotype of bees affected colony survival and the proportion of commercially viable colonies in spring, as indicated by greater rates of colony survival and commercially viable colonies for selected stock (43% survived and 33% were viable) in comparison to unselected stock (19% survived and 9% were viable) across all treatment groups. Indoor wintering improved spring bee population score, proportion of colonies surviving, and proportion of commercially viable colonies relative to outdoor wintering (73% of selected stock and 41% of unselected stock survived during indoor wintering). Selected stock showed better "tolerance" to varroa as the selected stock also maintained higher bee populations relative to unselected stock. However, there was no evidence of "resistance" in selected colonies (reduced mite densities). Collectively, this experiment showed that breeding can improve tolerance to varroa and this can help minimize colony loss through winter and improve colony wintering performance. Overall, colony wintering success of both genotypes of bees was better when colonies were wintered indoors than when colonies were wintered outdoors. © 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.

Stand Density and Canopy Gaps

Treesearch

Boris Zeide

2004-01-01

Estimation of stand density is based on a relationship between number of trees and their average diameter in fully stocked stands. Popular measures of density (Reineke’s stand density index and basal area) assume that number of trees decreases as a power function of diameter. Actually, number of trees drops faster than predicted by the power function because the number...

Growth and soil moisture in thinned lodgepole pine.

Treesearch

Walter G. Dahms

1971-01-01

A lodgepole pine levels-of-growing-stock study showed that trees growing at lower stand densities had longer crowns and grew more rapidly in diameter but did not grow significantly faster in height. Gross cubic-volume increment decreased with decreasing stand density. The decrease was small per unit of density at the higher densities but much greater at the lower...

Extreme value modelling of Ghana stock exchange index.

PubMed

Nortey, Ezekiel N N; Asare, Kwabena; Mettle, Felix Okoe

2015-01-01

Modelling of extreme events has always been of interest in fields such as hydrology and meteorology. However, after the recent global financial crises, appropriate models for modelling of such rare events leading to these crises have become quite essential in the finance and risk management fields. This paper models the extreme values of the Ghana stock exchange all-shares index (2000-2010) by applying the extreme value theory (EVT) to fit a model to the tails of the daily stock returns data. A conditional approach of the EVT was preferred and hence an ARMA-GARCH model was fitted to the data to correct for the effects of autocorrelation and conditional heteroscedastic terms present in the returns series, before the EVT method was applied. The Peak Over Threshold approach of the EVT, which fits a Generalized Pareto Distribution (GPD) model to excesses above a certain selected threshold, was employed. Maximum likelihood estimates of the model parameters were obtained and the model's goodness of fit was assessed graphically using Q-Q, P-P and density plots. The findings indicate that the GPD provides an adequate fit to the data of excesses. The size of the extreme daily Ghanaian stock market movements were then computed using the value at risk and expected shortfall risk measures at some high quantiles, based on the fitted GPD model.

Effect of stocking density and different diets on growth of Percula Clownfish, Amphiprion percula (Lacepede, 1802).

PubMed

Chambel, João; Severiano, Vera; Baptista, Teresa; Mendes, Susana; Pedrosa, Rui

2015-01-01

The aim of this study was to evaluate the influence of stocking density (0.5, 1, 2 and 3 fishL(-1)) and commercial marine fish diets (diet A, B, C and D) over four months on specific growth rate, condition factor, percentage without anomalous pigmentation (partial or total lack of white bands -miss-band) and survival of juvenile Amphiprion percula. Results showed that at 0.5 fishL(-1) densities induced the best survival (100%) and also the maximum percentage of fish without miss-band (58.33 +/-4.417%). The maximum SGR was obtained for the 0.5 fishL(-1) (0.459 ± 0.023% cm/day). However, the best condition factor (2.53 +/- 0.27) was achieved for 2 fishL(-1) densities. There were no significant differences in survival (68.9 to 84.5%), fish without miss-bands (18.03 to 26.92%) and condition factor (1.92 to 2.1) among diets during the experimental period. On the other hand, diet C (with 41% crude protein) supported the best SGR (0.485 ± 0.001% cmday(-1)). The results suggested that stocking density are critical and more relevant when compared with the different diet tested, namely on specific growth rate, condition factor, the miss-band and survival of juvenile percula clownfish. This study has particular significance with regards to anemonefishes husbandry in terms of survival and production efficiency.

Simulated effects of YY-male stocking and manual suppression for eradicating nonnative Brook Trout populations

USGS Publications Warehouse

Schill, Daniel J.; Meyer, Kevin A.; Hansen, Michael J.

2017-01-01

Eradication of nonnative Brook Trout Salvelinus fontinalis populations is difficult to achieve with standard techniques, such as electrofishing removal or piscicides; new approaches are needed. A novel concept is to stock “supermale” hatchery fish with wild conspecifics. Supermales (MYY) have two Y-chromosomes, resulting in offspring that are all males; over time, successful supermale reproduction could eradicate the wild population. We constructed an age-structured stochastic model to investigate the effects of manually suppressing wild fish and stocking MYY fingerlings on the long-term viability of hypothetical nonnative Brook Trout populations. In streams, an annual stocking rate of supermales equivalent to 50% of wild age-0 Brook Trout density combined with an annual selective suppression rate equivalent to 50% of wild Brook Trout density resulted in a time to extirpation of only 2–4 years if supermale fitness was equivalent to wild male fitness. However, time to extirpation in streams was 5–15 years if supermale fitness was 80% lower than wild male fitness. In alpine lakes, higher supermale stocking rates and nonselective gillnetting were required to eradicate Brook Trout populations. If supermales were assumed to be as fit as wild males, however, any supermale stocking rate greater than 49% in alpine lakes or 60% in streams achieved eradication in 10 years or less, regardless of the suppression rate. Because manual suppression and the stocking of MYY fingerlings can readily be conducted at the levels assumed in our simulations, use of such an integrated pest management (IPM) approach could extirpate undesirable Brook Trout populations within reasonably short periods of time. Given the recent successful development of an MYY Brook Trout broodstock capable of producing large numbers of MYY fingerlings and given the positive results of the present simulations for both streams and alpine lakes, field testing of MYY stocking is warranted within an IPM program that includes manual suppression for eradicating undesirable Brook Trout populations.

Biomass and carbon stock potential of Gliricidia Sepium as an alternative energy at Timor Tengah Utara Regency, East Nusa Tenggara Province, Indonesia

NASA Astrophysics Data System (ADS)

Prima, F. H.; Hariyadi; Hartono, A.

2018-03-01

The utilization of biomass from plants is one efforts for the fulfillment an availability of alternative energy in indonesia. Gliricidia sepium is a tolerant species that can grow in dry land. However its utilization as renewable energy source is non-optimized. This study aims to analyze the potential carbon stocks and biomass from Gliricidia sepium as a raw material for alternative energy in East Nusa Tenggara. This study was conducted in November 2015 and located in Humusu Sainiup, Timor Tengah Utara Regency, East Nusa Tenggara Province. The method used in collecting data was applied in three different land-use, namely monoculture Gliricidia sepium, polyculture between Gliricidia sepium and Leucaena leucocephala, and polyculture between Gliricidia sepium and Zea mays. We used the allometric equation from Ketterings namely B = 0.11ρD2+0,62 and C = 0.5 x B. The results showed that the different land-use will give different value of carbon stocks which is in this study the biggest value of carbon stocks was found in monoculture of Gliricidia sp (35.35 tC ha-1) compared with Gliricidia sp + Leucaena sp (18.83 tC ha-1), and Gliricidia sp + Zea mays (13.79 tC ha-1). The value of biomass and carbon stocks was influenced by wood density, trees density, and diameter at breast height (dbh).

Soil organic carbon distribution in an agricultural catchment in Southern Brazil: from hillslope to catchment scale.

NASA Astrophysics Data System (ADS)

Trigalet, Sylvain; Chartin, Caroline; Van Oost, Kristof; van Wesemael, Bas

2017-04-01

Understanding the soil organic carbon (SOC) distribution a few decades after conversion to cropland and plantations in a hilly catchment in southern Brazil is challenging due to scale-dependent controlling factors. Firstly, SOC, bulk density (BD) and texture were measured by depth intervals along 18 soil profiles located in three topographical positions (sloping plateau, central back slope and concave foot slope) in cropland and forest with contrasting slopes. SOC stocks in concave footslope position were not significantly different between fields on steep (11.1 kg C m-2) and gentle slopes (12.8 kg C m-2). However, in eroding profiles, SOC stocks are twice as high in fields on gentle slopes (17.6/12.6 kg C m-2) compared to steep slopes (8.3/7.1 kg C m-2). SOC stocks on steep slope on cropland (8.8 kg C m-2) are three times lower than SOC stocks on steep slope under undisturbed forest (23.7 kg C m-2). On gentle slopes, the effect of deforestation on SOC stocks was not so drastic (14.3 and 14.4 kg C m-2). Therefore, contrasting topography generates different patterns of SOC redistribution in the catchment. The effect of conversion to cropland is probably due to soil redistribution by water and tillage erosion aggravated by the steep terrain. Secondly, in order to assess the heterogeneity of SOC distribution at catchment scale, samples were collected at 10-20; 40-50 and 75-85 cm in 167 soil profiles sampled with an auger. SOC concentrations (gC kg-1 ) in numerous bulk soil samples (n = 378) were predicted by VIS-NIR spectroscopy and partial least-square regression models. SOC stocks were assessed by a mass preserving spline tool by interpolating SOC mass at the three non-contiguous depth intervals. Samples of calibration-validation dataset (n = 95) were used for physical SOC fractionation allowing the measurement of carbon associated with < 20 μm fraction. Multivariate linear regression models and Pearson correlation coefficients were used to assess the influence of several covariates on SOC stocks, SOC in bulk soil and fractions. This integrated approach highlights how SOC distribution is influenced by different proximal or distal controlling factors that are scale-dependent. Spectroscopy increases the density of samples available at catchment scale while SOC fractionation provides information on SOC quality on a representative subset of samples.

Inventory-based estimates of forest biomass carbon stocks in China: A comparison of three methods

Treesearch

Zhaodi Guo; Jingyun Fang; Yude Pan; Richard Birdsey

2010-01-01

Several studies have reported different estimates for forest biomass carbon (C) stocks in China. The discrepancy among these estimates may be largely attributed to the methods used. In this study, we used three methods [mean biomass density method (MBM), mean ratio method (MRM), and continuous biomass expansion factor (BEF) method (abbreviated as CBM)] applied to...

Factors affecting stall use for different freestall bases.

PubMed

Wagner-Storch, A M; Palmer, R W; Kammel, D W

2003-06-01

The objective of this study was to compare stall use (stall occupancy and cow position) by barn side for factors affecting stall use. A closed circuit television system recorded stall use four times per day for a 9-mo period starting May 9, 2001. Six factors were analyzed: stall base, distance to water, stall location within stall base section, stall location within barn, inside barn temperature, and length of time cows were exposed to stall bases. Two barn sides with different stocking densities were analyzed: low (66%), with cows milked by robotic milker; and high (100%), with cows milked 2X in parlor. Six stall base types were tested: two mattresses, a waterbed, a rubber mat, concrete, and sand (high side only). The base types were grouped 3 to 7 stalls/section and randomly placed in each row. Cows spent more time in mattress-based stalls, but the highest percentage lying was in sand-based stalls. The following significant stall occupancy percentages were found: sand had the highest percentage of cows lying on the high stocking density side (69%), followed by mattress type 1 (65%) > mattress type 2 (57%) > waterbed (45%) > rubber mat (33%) > concrete (23%). Mattress type 1 had the highest percentage stalls occupied (88%), followed by mattress type 2 (84%) > sand (79%) > soft rubber mat (65%) > waterbed (62%) > concrete (39%). On the low stocking rate side, mattress type 1 had the highest percentage cows lying (45%) and occupied (59.6%), followed by mattress type 2 > waterbed > soft rubber mat > concrete. Cow lying and stalls occupied percentages were highest for stalls 1) not at the end of a section, and 2) on the outside row, and varied by base type for time cows exposed to stalls and inside barn temperature. Lying and occupied percentages were different for different mattress types. The percentage of stalls with cows standing was higher for mat and mattress-based stalls. Results show mattress type 1 and sand to be superior and rubber mats and concrete inferior stall bases.

Decline of lake herring (Coregonus artedii) in Lake Superior: an analysis of the Wisconsin herring fishery, 1936-78

USGS Publications Warehouse

Selgeby, James H.

1982-01-01

Annual harvests of lake herring (Coregonus artedii) in American waters of Lake Superior declined from an average of 2 million kg in 1936–62 to less than 25 000 kg in 1978. Analysis of commercial fishing records revealed that the sequential overexploitation of discrete unit stocks caused the collapse of the herring population in Wisconsin waters. In each of six major spawning areas, catch exceeded the productive capacity of the stock and the stock failed. Because stocks in the six areas were exploited sequentially, mostly in groups of two or three simultaneously, the demise of the stocks was not readily apparent until the last two failed in the early 1960s. After the collapse of the last major spawning stock, the fishery dwindled but may have continued to overexploit the remaining small stocks. The residual populations were apparently able only to replace themselves. Some form of density-independent mortality was apparently operating to prevent their recovery during the 1960s and 1970s.Key words: lake herring, overfishing, Lake Superior

Estimating forest carbon dynamics in South Korea from 1954 to 2050 - coupling global forestry model and forest soil carbon model

NASA Astrophysics Data System (ADS)

Lee, Jongyeol; Kim, Moonil; Lakyda, Ivan; Pietsch, Stephan; Shvidenko, Anatoly; Kraxner, Florian; Forsell, Nicklas; Son, Yowhan

2016-04-01

There have been demands on reporting national forest carbon (C) inventories to mitigate global climate change. Global forestry models estimate growth of stem volume and C at various spatial and temporal scales but they do not consider dead organic matter (DOM) C. In this study, we simulated national forest C dynamics in South Korea with a calibrated global forestry model (G4M model) and a module of DOM C dynamics in Korean forest C model (FBDC model). 3890 simulation units (1-16 km2) were established in entire South Korea. Growth functions of stem for major tree species (Pinus densiflora, P. rigida, Larix kaempferi, Quercus variabilis, Q. mongolica, and Q. acutissima) were estimated by internal mechanism of G4M model and Korean yield tables. C dynamics in DOMs were determined by balance between input and output (decomposition) of DOMs in the FBDC model. Annual input of DOM was estimated by multiplying C stock of biomass compartment with turnover rate. Decomposition of DOM was estimated by C stock of DOM, mean air temperature, and decay rate. C stock in each C pool was initialized by spin-up process with consideration of severe deforestation by Japanese exploitation and Korean War. No disturbance was included in the simulation process. Total forest C stock (Tg C) and mean C density (Mg C ha-1) decreased from 657.9 and 112.1 in 1954 to 607.2 and 103.4 in 1973. Especially, C stock in mineral soil decreased at a rate of 0.5 Mg C ha-1 yr-1 during the period due to suppression of regeneration. However, total forest C stock (Tg C) and mean C density (Mg C ha-1) gradually increased from 607.0 and 103.4 in 1974 to 1240.7 and 211.3 in 2015 due to the national reforestation program since 1973. After the reforestation program, Korean forests became C sinks. Model estimates were also verified by comparison of these estimates and national forest inventory data (2006-2010). High similarity between the model estimates and the inventory data showed a reliability of down-scaled global forestry model and integration of DOM C module. Finally, total C stock gradually increased to 1749.8 Tg C in 2050 at a rate of 2.5 Tg C yr-1 and it might be attributed to mature of forest. However, total forest C stock might be overestimated in the future due to the exclusion of disturbance in simulation. This study was supported by Korea Forest Service (S111315L100120) and Korean Ministry of Environment (2014001310008).

Development of high temperature silicone adhesive formulations for thermal protection system applications

NASA Technical Reports Server (NTRS)

Hockridge, R. R.

1973-01-01

Trade-off studies and screening evaluations were made of commercial polymers and silicone foam sheet stock. A low modulus, low density 0.26 gm/cc modification was developed of the GE-RESD PD-200 system based upon GE RTV-560 silicone polymer. The bond system modification was initially characterized for mechanical and thermal properties, evaluated for application methods, and its capability demonstrated as a strain arrestor bond system.

JPRS Report, Science & Technology Europe

DTIC Science & Technology

1992-08-12

Head on Chip Industry, Plans [Heinrich von Pierer Interview; Bonn DIE WELT, 15 Jun 92] 33 Swiss Contraves Develops High-Density Multichip Module... Investment costs are low because the method is based on low pressure, 0.1-1.0 MPA, during injection. This permits the use of simpler molds and...For example, ABS Pumpen AG [ABS Pumps German Stock Corporation] in Lohmar needed 1.5 years to define the "Ceramic Compo- nents for Friction

What distinguishes individual stocks from the index?

NASA Astrophysics Data System (ADS)

Wagner, F.; Milaković, M.; Alfarano, S.

2010-01-01

Stochastic volatility models decompose the time series of financial returns into the product of a volatility factor and an iid noise factor. Assuming a slow dynamic for the volatility factor, we show via nonparametric tests that both the index as well as its individual stocks share a common volatility factor. While the noise component is Gaussian for the index, individual stock returns turn out to require a leptokurtic noise. Thus we propose a two-component model for stocks, given by the sum of Gaussian noise, which reflects market-wide fluctuations, and Laplacian noise, which incorporates firm-specific factors such as firm profitability or growth performance, both of which are known to be Laplacian distributed. In the case of purely Gaussian noise, the chi-squared probability for the density of individual stock returns is typically on the order of 10-20, while it increases to values of O(1) by adding the Laplace component.

Analyses of the structure of group correlations in Korean financial markets

NASA Astrophysics Data System (ADS)

Ko, Jeung Su; Lim, Gyuchang; Kim, Kyungsik

2012-12-01

In this paper, we construct and analyze the structure of cross-correlations in two Korean stock markets, the Korea Composite Stock Price Index (KOSPI) and the Korea Securities Dealers Automated Quotation (KOSDAQ). We investigate a remarkable agreement between the theoretical prediction and the empirical data concerning the density of eigenvalues in the KOSPI and the KOSDAQ. We estimate daily cross-correlations with respect to price fluctuations of 629 KOSPI and 650 KOSDAQ stock entities for the period from 2006 to 2010. The research for the structure of group correlations undress the market-wide effect by using the Markowitz multi-factor model and network-based approach. We find stock entities that involve the same business sectors and verify the structure of group correlations by applying a network-based approach. In particular, the KOSPI has a dense correlation besides overall group correlations for stock entities, whereas both correlations are less for the KOSDAQ than for the KOSPI.

Carbon stock and its responses to climate change in Central Asia.

PubMed

Li, Chaofan; Zhang, Chi; Luo, Geping; Chen, Xi; Maisupova, Bagila; Madaminov, Abdullo A; Han, Qifei; Djenbaev, Bekmamat M

2015-05-01

Central Asia has a land area of 5.6 × 10(6) km(2) and contains 80-90% of the world's temperate deserts. Yet it is one of the least characterized areas in the estimation of the global carbon (C) stock/balance. This study assessed the sizes and spatiotemporal patterns of C pools in Central Asia using both inventory (based on 353 biomass and 284 soil samples) and process-based modeling approaches. The results showed that the C stock in Central Asia was 31.34-34.16 Pg in the top 1-m soil with another 10.42-11.43 Pg stored in deep soil (1-3 m) of the temperate deserts. They amounted to 18-24% of the global C stock in deserts and dry shrublands. The C stock was comparable to that of the neighboring regions in Eurasia or major drylands around the world (e.g. Australia). However, 90% of Central Asia C pool was stored in soil, and the fraction was much higher than in other regions. Compared to hot deserts of the world, the temperate deserts in Central Asia had relatively high soil organic carbon density. The C stock in Central Asia is under threat from dramatic climate change. During a decadal drought between 1998 and 2008, which was possibly related to protracted La Niña episodes, the dryland lost approximately 0.46 Pg C from 1979 to 2011. The largest C losses were found in northern Kazakhstan, where annual precipitation declined at a rate of 90 mm decade(-1) . The regional C dynamics were mainly determined by changes in the vegetation C pool, and the SOC pool was stable due to the balance between reduced plant-derived C influx and inhibited respiration. © 2015 John Wiley & Sons Ltd.

Proceedings of the National Silviculture Workshop: Density of Stocking Control; Eugene, Oregon; October 13-15, 1976

Treesearch

Jack H. Usher; Daniel B. Jones; A. R. Stage; Benjamin A. Roach; Gilbert B. Schubert; Darrell W. Crawford; Gilbert H. Schubert; Walter Fox; Edward A. Smith; Richard E. Lowrey Sofes; Richard F. Watt

1976-01-01

The 1976 National Silviculture Workshop was held in Eugene, Oregon, on October 13-15, 1976. The objectives were to discuss second growth management of individual stands, with particular emphasis on the control of stand density.

Local fluctuations of the signed traded volumes and the dependencies of demands: a copula analysis

NASA Astrophysics Data System (ADS)

Wang, Shanshan; Guhr, Thomas

2018-03-01

We investigate how the local fluctuations of the signed traded volumes affect the dependence of demands between stocks. We analyze the empirical dependence of demands using copulas and show that they are well described by a bivariate K copula density function. We find that large local fluctuations strongly increase the positive dependence but lower slightly the negative one in the copula density. This interesting feature is due to cross-correlations of volume imbalances between stocks. Also, we explore the asymmetries of tail dependencies of the copula density, which are moderate for the negative dependencies but strong for the positive ones. For the latter, we reveal that large local fluctuations of the signed traded volumes trigger stronger dependencies of demands than of supplies, probably indicating a bull market with persistent raising of prices.

Basal area or stocking percent: which works best in controlling density in natural shortleaf pine stands

Treesearch

Ivan L. Sander

1986-01-01

Results from a shortleaf pine thinning study in Missouri show that continually thinning a stand to the same basal area will eventually create an understocked stand and reduce yields. Using stocking percent to control thinning intensity allows basal area to increase as stands get older. The best yield should occur when shortleaf pine is repeatedly thinned to 60 percent...

Quality response of 29-year-old, even-aged central hardwoods after thinning

Treesearch

David L. Sonderman

1984-01-01

Describes the quality response of a 29-year-old upland hardwood stand grown for 6 years under different levels of residual stand density. Both the number of defects per square foot of surface area and the number of epicormic branches changed under different stocking levels. The results suggest that the effect of stocking on potential stem quality of certain species may...

Stand density management of southern bottomland hardwoods

Treesearch

J.C.G. Goelz; J.S. Meadows

1997-01-01

We present tools to guide stand density management of southern bottomiand hardwoods and we provide guidance in their implementation. We present stocking guides for southern bottomland hardwoods and variants for associated forest types, water tupelo (Nyssa aquarica L.) and sweetgum (Liquidumbar styraciflua L.). The A-line...

Effect of dietary supplementation of l-tryptophan on thermal tolerance and oxygen consumption rate in Cirrhinus mrigala fingerlings under varied stocking density.

PubMed

Tejpal, C S; Sumitha, E B; Pal, A K; Shivananda Murthy, H; Sahu, N P; Siddaiah, G M

2014-04-01

A 60 day feeding trial was conducted to study the effect of dietary l-tryptophan on thermal tolerance and oxygen consumption rate of freshwater fish, mrigala, Cirrhinus mrigala reared under ambient temperature at low and high stocking density. Four hundred eighty fingerlings were distributed into eight experimental groups. Four groups each of low density group (10 fishes/75L water) and higher density group (30 fishes/75L water) were fed a diet containing 0, 0.68, 1.36 or 2.72% l-tryptophan in the diet, thus forming eight experimental groups namely, Low density control (LC) (basal feed +0% l-tryptophan); LT1 (basal feed+0.68% l-tryptophan); LT2 (basal feed+1.36% l-tryptophan); LT3 (basal feed+2.72% l-tryptophan); high density control (HC) (basal feed+0% l-tryptophan); HT1 (basal feed+0.68% l-tryptophan); HT2 (basal feed+1.36% l-tryptophan); and HT3 (basal feed+2.72% l-tryptophan) were fed at 3% of the body weight. The test diets having crude protein 34.33±0.23 to 35.81±0.18% and lipid 423.49±1.76 to 425.85±0.31KCal/100g were prepared using purified ingredients. The possible role of dietary l-tryptophan on thermal tolerance and oxygen consumption rate was assessed in terms of critical thermal maxima (CTMax), critical thermal minima (CTMin), lethal thermal maxima (LTMax) and lethal thermal minima (LTMin). The CTMax, CTMin, LTMax and LTMin values were found to be significantly higher (p<0.05) in the treatment groups with CTMax 42.94±0.037 (LT2); LT Max 43.18±0.070 (LT2); CTMin 10.47±0.088 (LT2) and LTMin 9.42±0.062 (LT3), whereas the control group showed a lower tolerance level. The same trend was observed in the high density group (CTMax 42.09±0.066 (LT3); LTMax 43 23±0.067 (HT3); CTMin 10.98±0.040 (HT3) and LTMin 9.74±0.037 (HT3). However, gradual supplementation of dietary l-tryptophan in the diet significantly reduced the oxygen consumption rate in both the low density group (Y=-26.74x+222.4, r²=0.915) and the high density group (Y=-32.96x+296.5, r²=0.8923). Dietary supplementation of l-tryptophan at a level of 1.36% improved the thermal tolerance level and reduced the oxygen consumption rate in C. mrigala fingerlings. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterization and reproducibility of HepG2 hanging drop spheroids toxicology in vitro.

PubMed

Hurrell, Tracey; Ellero, Andrea Antonio; Masso, Zelie Flavienne; Cromarty, Allan Duncan

2018-02-21

Hepatotoxicity remains a major challenge in drug development despite preclinical toxicity screening using hepatocytes of human origin. To overcome some limitations of reproducing the hepatic phenotype, more structurally and functionally authentic cultures in vitro can be introduced by growing cells in 3D spheroid cultures. Characterisation and reproducibility of HepG2 spheroid cultures using a high-throughput hanging drop technique was performed and features contributing to potential phenotypic variation highlighted. Cultured HepG2 cells were seeded into Perfecta 3D® 96-well hanging drop plates and assessed over time for morphology, viability, cell cycle distribution, protein content and protein-mass profiles. Divergent aspects which were assessed included cell stocks, seeding density, volume of culture medium and use of extracellular matrix additives. Hanging drops are advantageous due to no complex culture matrix being present, enabling background free extractions for downstream experimentation. Varying characteristics were observed across cell stocks and batches, seeding density, culture medium volume and extracellular matrix when using immortalized HepG2 cells. These factors contribute to wide-ranging cellular responses and highlights concerns with respect to generating a reproducible phenotype in HepG2 hanging drop spheroids. Copyright © 2018 Elsevier Ltd. All rights reserved.

Shade tree diversity and aboveground carbon stocks in Theobroma cacao agroforestry systems: implications for REDD+ implementation in a West African cacao landscape.

PubMed

Dawoe, Evans; Asante, Winston; Acheampong, Emmanuel; Bosu, Paul

2016-12-01

The promotion of cacao agroforestry is one of the ways of diversifying farmer income and creating incentives through their inclusion in REDD+ interventions. We estimated the aboveground carbon stocks in cacao and shade trees, determined the floristic diversity of shade trees and explored the possibility of implementing REDD+ interventions in cacao landscapes. Using replicated multi-site transect approach, data were collected from nine 1-ha plots established on 5 km long transects in ten cacao growing districts in Ghana West Africa. Biomass of cacao and shade trees was determined using allometric equations. One thousand four hundred and one (1401) shade trees comprising 109 species from 33 families were recorded. Total number of species ranged from 34 to 49. Newbouldia laevis (Bignoniacea) was the most frequently occurring specie and constituted 43.2 % of all shade trees. The most predominant families were Sterculiaceae and Moraceae (10 species each), followed by Meliaceae and Mimosaceae (8 species each) and Caesalpiniacaea (6 species). Shannon diversity indices (H', H max and J') and species richness were low compared to other similar studies. Shade tree densities ranged from 16.2 ± 3.0 to 22.8 ± 1.7 stems ha -1 and differed significantly between sites. Carbon stocks of shade trees differed between sites but were similar in cacao trees. The average C stock in cacao trees was 7.45 ± 0.41 Mg C ha -1 compared with 8.32 ± 1.15 Mg C ha -1 in the shade trees. Cacao landscapes in Ghana have the potential of contributing to forest carbon stocks enhancement by increasing the stocking density of shade trees to recommended levels.

Distribution characteristics of stock market liquidity

NASA Astrophysics Data System (ADS)

Luo, Jiawen; Chen, Langnan; Liu, Hao

2013-12-01

We examine the distribution characteristics of stock market liquidity by employing the generalized additive models for location, scale and shape (GAMLSS) model and three-minute frequency data from Chinese stock markets. We find that the BCPE distribution within the GAMLSS framework fits the distributions of stock market liquidity well with the diagnosis test. We also find that the stock market index exhibits a significant impact on the distributions of stock market liquidity. The stock market liquidity usually exhibits a positive skewness, but a normal distribution at a low level of stock market index and a high-peak and fat-tail shape at a high level of stock market index.

Quantifying long-term changes in carbon stocks and forest structure from Amazon forest degradation

NASA Astrophysics Data System (ADS)

Rappaport, Danielle I.; Morton, Douglas C.; Longo, Marcos; Keller, Michael; Dubayah, Ralph; Nara dos-Santos, Maiza

2018-06-01

Despite sustained declines in Amazon deforestation, forest degradation from logging and fire continues to threaten carbon stocks, habitat, and biodiversity in frontier forests along the Amazon arc of deforestation. Limited data on the magnitude of carbon losses and rates of carbon recovery following forest degradation have hindered carbon accounting efforts and contributed to incomplete national reporting to reduce emissions from deforestation and forest degradation (REDD+). We combined annual time series of Landsat imagery and high-density airborne lidar data to characterize the variability, magnitude, and persistence of Amazon forest degradation impacts on aboveground carbon density (ACD) and canopy structure. On average, degraded forests contained 45.1% of the carbon stocks in intact forests, and differences persisted even after 15 years of regrowth. In comparison to logging, understory fires resulted in the largest and longest-lasting differences in ACD. Heterogeneity in burned forest structure varied by fire severity and frequency. Forests with a history of one, two, and three or more fires retained only 54.4%, 25.2%, and 7.6% of intact ACD, respectively, when measured after a year of regrowth. Unlike the additive impact of successive fires, selective logging before burning did not explain additional variability in modeled ACD loss and recovery of burned forests. Airborne lidar also provides quantitative measures of habitat structure that can aid the estimation of co-benefits of avoided degradation. Notably, forest carbon stocks recovered faster than attributes of canopy structure that are critical for biodiversity in tropical forests, including the abundance of tall trees. We provide the first comprehensive look-up table of emissions factors for specific degradation pathways at standard reporting intervals in the Amazon. Estimated carbon loss and recovery trajectories provide an important foundation for assessing the long-term contributions from forest degradation to regional carbon cycling and advance our understanding of the current state of frontier forests.

Estimating Soil Organic Carbon Stocks and Spatial Patterns with Statistical and GIS-Based Methods

PubMed Central

Zhi, Junjun; Jing, Changwei; Lin, Shengpan; Zhang, Cao; Liu, Qiankun; DeGloria, Stephen D.; Wu, Jiaping

2014-01-01

Accurately quantifying soil organic carbon (SOC) is considered fundamental to studying soil quality, modeling the global carbon cycle, and assessing global climate change. This study evaluated the uncertainties caused by up-scaling of soil properties from the county scale to the provincial scale and from lower-level classification of Soil Species to Soil Group, using four methods: the mean, median, Soil Profile Statistics (SPS), and pedological professional knowledge based (PKB) methods. For the SPS method, SOC stock is calculated at the county scale by multiplying the mean SOC density value of each soil type in a county by its corresponding area. For the mean or median method, SOC density value of each soil type is calculated using provincial arithmetic mean or median. For the PKB method, SOC density value of each soil type is calculated at the county scale considering soil parent materials and spatial locations of all soil profiles. A newly constructed 1∶50,000 soil survey geographic database of Zhejiang Province, China, was used for evaluation. Results indicated that with soil classification levels up-scaling from Soil Species to Soil Group, the variation of estimated SOC stocks among different soil classification levels was obviously lower than that among different methods. The difference in the estimated SOC stocks among the four methods was lowest at the Soil Species level. The differences in SOC stocks among the mean, median, and PKB methods for different Soil Groups resulted from the differences in the procedure of aggregating soil profile properties to represent the attributes of one soil type. Compared with the other three estimation methods (i.e., the SPS, mean and median methods), the PKB method holds significant promise for characterizing spatial differences in SOC distribution because spatial locations of all soil profiles are considered during the aggregation procedure. PMID:24840890

Determining maximum stand density index in mixed species stands for strategic-scale stocking assessments

Treesearch

Chris W. Woodall; Patrick D. Miles; John S. Vissage

2005-01-01

Stand density index (SDI), although developed for use in even-aged monocultures, has been used for assessing stand density in large-scale forest inventories containing diverse tree species and size distributions. To improve application of SDI in unevenaged, mixed species stands present in large-scale forest inventories, trends in maximum SDI across diameter classes...

Influence of residual stand density on regeneration of northern hardwoods

Treesearch

W. B. Leak; Dale S. Solomon

1975-01-01

In a study of hardwood regeneration, experimental plots were treated to produce residual densities of 40, 60, 80, and 100 square feet of basal area per acre with 30, 45, and 60 percent sawtimber. After 9 years, numbers of stems and percent stocking were estimated for each species and they were rated for reproductive potential under different residual densities. Data...

Effects of stand density on top height estimation for ponderosa pine

Treesearch

Martin Ritchie; Jianwei Zhang; Todd Hamilton

2012-01-01

Site index, estimated as a function of dominant-tree height and age, is often used as an expression of site quality. This expression is assumed to be effectively independent of stand density. Observation of dominant height at two different ponderosa pine levels-of-growing-stock studies revealed that top height stability with respect to stand density depends on the...

Growth of ponderosa pine thinned to different stocking levels in central Oregon: 30-year results.

Treesearch

P.H. Cochran; James W. Barrett

1999-01-01

Periodic annual increments (PAI) for survivor diameters decreased curvilinearly with increasing stand density. Gross volume and basal areas PAIs increased linearly with increasing stand density. Growth of basal area and volume for the 20 largest trees per acre were reduced curvilinearly with increasing stand density. Bark beetles were the primary cause of mortality. No...

Assessing Carbon Storage and Sequestration of Seagrass Meadows on the Pacific Coast of Canada

NASA Astrophysics Data System (ADS)

Postlethwaite, V. R.; McGowan, A. E.; Robinson, C.; Kohfeld, K. E.; Pellatt, M. G.; Yakimishyn, J.; Chastain, S. G.

2016-12-01

Recent estimates suggest that seagrasses are highly efficient carbon sinks, storing a disproportionate amount of carbon for their relatively small area (only approximately 0.2% of the global ocean), and that they may bury carbon up to 12 times faster than terrestrial forests. Unfortunately, seagrass meadows are being lost at a rate of 0.4-2.6% yr-1, potentially releasing 0.15-1.02 Pg (billion tonnes) carbon dioxide into the atmosphere annually. Research on seagrass carbon stocks has been mainly limited to areas in the Mediterranean, Southeast Asia, and Western Australia, and specifically has been very limited in the Northeast Pacific. We aim to characterize the carbon storage and sequestration occurring in the Pacific Rim National Park Reserve and the Clayoquot Sound area, off the western coast of Vancouver Island, British Columbia (BC). Each of our sites varied in environmental characteristics representative of BC's seagrass meadows, including freshwater influence. Six cores, plus one from a "reference" site were taken from each meadow. Loss on ignition (LOI) and elemental analysis will be used to determine organic C and carbonate content. Additionally, we will use dry bulk density, 210Pb dating and seagrass density data to determine carbon accumulation rates and total meadow carbon stocks to provide a comprehensive picture of carbon storage and sequestration in BC's seagrass meadows. Carbon storage results will contribute to global estimates of seagrass carbon stocks via the Commission for Environmental Cooperation, as well as assist in marine ecosystem conservation planning and help in understanding the value of these ecosystems, especially as a means of climate change mitigation.

Recent changes in the estimation of standing dead tree biomass and carbon stocks in the U.S. forest inventory

Treesearch

Grant M. Domke; Christopher W. Woodall; James E. Smith

2012-01-01

Until recently, standing dead tree biomass and carbon (C) has been estimated as a function of live tree growing stock volume in the U.S. Forest Service, Forest Inventory and Analysis (FIA) Program. Traditional estimates of standing dead tree biomass/C attributes were based on merchantability standards that did not reflect density reductions or structural loss due to...

Forty years later at Taylor Woods: Merging the old and new (P-53)

Treesearch

John D. Bailey

2008-01-01

The Taylor Woods "Levels-of-Growing-Stock" study was established in 1962 to create a replicated ponderosa pine density experiment for the Southwest, making a valuable addition to research in the Fort Valley Experimental Forest. Basal area treatments ranged from 5-20 m2/ha (19-80 ft2/ac) when installed, designed as growing stock levels 30/40, 60, 80, 100, 120...

Critical thresholds in sea lice epidemics: evidence, sensitivity and subcritical estimation

PubMed Central

Frazer, L. Neil; Morton, Alexandra; Krkošek, Martin

2012-01-01

Host density thresholds are a fundamental component of the population dynamics of pathogens, but empirical evidence and estimates are lacking. We studied host density thresholds in the dynamics of ectoparasitic sea lice (Lepeophtheirus salmonis) on salmon farms. Empirical examples include a 1994 epidemic in Atlantic Canada and a 2001 epidemic in Pacific Canada. A mathematical model suggests dynamics of lice are governed by a stable endemic equilibrium until the critical host density threshold drops owing to environmental change, or is exceeded by stocking, causing epidemics that require rapid harvest or treatment. Sensitivity analysis of the critical threshold suggests variation in dependence on biotic parameters and high sensitivity to temperature and salinity. We provide a method for estimating the critical threshold from parasite abundances at subcritical host densities and estimate the critical threshold and transmission coefficient for the two epidemics. Host density thresholds may be a fundamental component of disease dynamics in coastal seas where salmon farming occurs. PMID:22217721

Based on BP Neural Network Stock Prediction

ERIC Educational Resources Information Center

Liu, Xiangwei; Ma, Xin

2012-01-01

The stock market has a high profit and high risk features, on the stock market analysis and prediction research has been paid attention to by people. Stock price trend is a complex nonlinear function, so the price has certain predictability. This article mainly with improved BP neural network (BPNN) to set up the stock market prediction model, and…

Increased natural mortality at low abundance can generate an Allee effect in a marine fish.

PubMed

Kuparinen, Anna; Hutchings, Jeffrey A

2014-10-01

Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite-a demographic Allee effect. Northwest Atlantic cod (Gadus morhua) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing.

Climate-driven trends in stem wood density of tree species in the eastern United States: Ecological impact and implications for national forest carbon assessments

Treesearch

Brian J. Clough; Miranda T. Curzon; Grant M. Domke; Matthew B. Russell; Christopher W. Woodall

2017-01-01

Aim: For trees, wood density is linked to competing energetic demands and therefore reflects responses to the environment. Climatic trends in wood density are recognized, yet their contribution to regional biogeographical patterns or impact on forest biomass stocks is not understood. This study has the following two objectives: (O1) to characterize wood density–climate...

Effect of climate region and stocking density on ostrich (Struthio camelus) productive performances.

PubMed

Bouyeh, M; Seidavi, A; Mohammadi, H; Sahoo, A; Laudadio, V; Tufarelli, V

2017-02-01

The effects of three climates (hot and dry, mild and humid and Alpine) and three flock densities (<100, 100-300 and >300 m 2 ) on ostrich reproductive and productive traits were studied. Data were compared with the benchmark target sets by the World Ostrich Association (Ostrich benchmark Performance Targets. Version 2, May, 2008) for reproductive qualifications of ostrich. No significant difference was observed on egg production, weight, fertility, hatchability and day-old chicks weight among the three climate conditions; however, the Alpine climate had a lower performance trend. Mild and humid climates had a significant effect of age at sexual maturity for both males and females as well as on the duration of egg production season. Stocking density did not show significant difference on egg production, hatchability, age of male and female at sexual maturity and on duration of egg production season, while an area >300 m 2 showed a reduction in egg weight and day-old chick weight. Further, an area <100 m 2 led to a weaker ostrich fertility rate. Results showed that the ostrich would have a better performance under hot and dry and mild and humid climates as compared to Alpine climate with a stocking density of 100-300 m 2 area per breeder bird. Thus, climatic intervention strategies at Alpine regions may be carried out for maintaining optimal reproductive qualification of ostrich so as to improve the productivity in this sector. © 2016 Blackwell Verlag GmbH.

Temporal and spatial distributions of dominant shrimp stocks and their relationship with the hydrological environment in the East China Sea

NASA Astrophysics Data System (ADS)

Lü, Huaqing; Song, Haitang; Bayly, Chris

2007-10-01

To provide a scientific and technological base for fishery administration, holding a moratorium on fishing, and combating habitat degradation, a shrimp stock survey was carried out in May, August, and November 1998 and in February 1999. The study was conducted in the area between 26°00' N and 33°00' N and to the west of 127°00' E in the East China Sea using a multi-sac trawl-net, with 115 stations being sampled. Up to 2001, we had found 121 species, which belong to 63 genera under 22 families, and 41 species are of high economic value and in great abundance. Nine shrimp species were of great economic importance, whose stock accounted for 76.8% of the demersal total. They were Parapenaeus fissuroides, Metapenaeopsis philippi, Palaemon gravieri, Metapenaeopsis barbata, Solenocera koelbeli, Solenocera crassicornis, Trachypenaeus curvirostris, Solenocera melantho and Parapenaeopsis hardwickii (listed in stock order). The nine species belong to the curythermal and eurysaline community and high thermal and high saline community, had different migration patterns and stocks, and their distribution patterns could be generally classified into three types: (1) dominating in the north or the south; (2) dominating to the north of and in the coast to the south of 30°00' N; and (3) dominating to the east of 60 m isobath, which were related to six water masses in the ECS near two lines, i.e., the 60 m isobath and 30°00'N latitudinal lines. Densely habited shrimps were found in all four seasons due to temperature and salinity frontiers and upwelling. The general stock density index was relatively higher in spring, summer, and autumn, when it surpassed 10 kg/h, while in winter, it was only 6.8 kg/h which might be caused by overfishing. According to the spawning areas of the nine species and their distribution patterns, to attain sustainable development of the shrimp fishery in the ECS, it is imperative to protect fishing areas and to hold a moratorium on catching to the west of 60 m isobath from April through October, and between 60 m and 100 m isobaths and to the south of 30°N from June through August and to limit fishing in winter.

Potential Carbon Stock Changes in Arizona's Ecosystems Due to Projected Climate Change

NASA Astrophysics Data System (ADS)

Finley, B. K.; Ironside, K.; Hungate, B. A.; Hurteau, M.; Koch, G. W.

2011-12-01

Climate change can alter the role of plants and soils as sources or sinks of atmospheric carbon dioxide and result in changes in long-term carbon storage. To understand the sensitivity of Arizona's ecosystems to climate change, we quantified the present carbon stocks in Arizona's major ecosystem types using the NASA-CASA (Carnegie Ames Stanford Approach) model. Carbon stocks for each vegetation type included surface mineral soil, dead wood litter, standing wood and live leaf biomass. The total Arizona ecosystem carbon stock is presently 1775 MMtC, 545 MMtC of which is in Pinus ponderosa and Pinus edulis forests and woodlands. Evergreen forest vegetation, predominately Pinus ponderosa, has the largest current C density at 11.3 kgC/m2, while Pinus edulis woodlands have a C density of 6.0 kgC/m2. A change in climate will impact the suitable range for each tree species, and consequentially the amount of C stored. Present habitat ranges for these tree species are projected to have widespread mortality and likely will be replaced by herbaceous species, resulting in a loss of C stored. We evaluated the C storage implications over the 2010 to 2099 period of climate change based on output from GCMs with contrasting projections for the southwestern US: MPI-ECHAM5, which projects warming and reduced precipitation, and UKMO-HadGEM, which projects warming and increased precipitation. These projected changes are end points of a spectrum of possible future climate scenarios. The vegetation distribution models used describe potential suitable habitat, and we assumed that the growth rate for each vegetation type would be one-third of the way to full C density for each 30 year period up to 2099. With increasing temperature and decreasing precipitation predictions under the MPI-ECHAM5 model, P. ponderosa and P. edulis vegetation show a decrease in carbon stored from 545 MMtC presently to 116 MMtC. With the combined increase in temperature and precipitation, C storage in these vegetation types is projected to increase to 808 MMtC. Our results indicate that future C storage in Arizona is highly dependent on precipitation. Given that most climate models for the Southwest predict a more arid future, it is likely that C storage will decrease in Arizona ecosystems, as it has in response to recent droughts, reducing mitigation of rising human emissions.

Another Look at the Volatility of Stock Prices

ERIC Educational Resources Information Center

Maruszewski, Richard F., Jr.

2007-01-01

Investors are interested in the volatility of a stock for various reasons. One investor may desire to purchase a low volatility stock for peace of mind. Another may be interested in a high volatility stock in order to have the opportunity to buy low and sell high as the price of the stock oscillates. This author had the fortunate timing of reading…

Massive carbon addition to an organic-rich Andosol increased the subsoil but not the topsoil carbon stock

NASA Astrophysics Data System (ADS)

Zieger, Antonia; Kaiser, Klaus; Ríos Guayasamín, Pedro; Kaupenjohann, Martin

2018-05-01

Andosols are among the most carbon-rich soils, with an average of 254 Mg ha-1 organic carbon (OC) in the upper 100 cm. A current theory proposes an upper limit for OC stocks independent of increasing carbon input, because of finite binding capacities of the soil mineral phase. We tested the possible limits in OC stocks for Andosols with already large OC concentrations and stocks (212 g kg-1 in the first horizon, 301 Mg ha-1 in the upper 100 cm). The soils received large inputs of 1800 Mg OC ha-1 as sawdust within a time period of 20 years. Adjacent soils without sawdust application served as controls. We determined total OC stocks as well as the storage forms of organic matter (OM) of five horizons down to 100 cm depth. Storage forms considered were pyrogenic carbon, OM of < 1.6 g cm-3 density and with little to no interaction with the mineral phase, and strongly mineral-bonded OM forming particles of densities between 1.6 and 2.0 g cm-3 or > 2.0 g cm-3. The two fractions > 1.6 g cm-3 were also analysed for aluminium-organic matter complexes (Al-OM complexes) and imogolite-type phases using ammonium-oxalate-oxalic-acid extraction and X-ray diffraction (XRD). Pyrogenic organic carbon represented only up to 5 wt % of OC, and thus contributed little to soil OM. In the two topsoil horizons, the fraction between 1.6 and 2.0 g cm-3 had 65-86 wt % of bulk soil OC and was dominated by Al-OM complexes. In deeper horizons, the fraction > 2.0 g cm-3 contained 80-97 wt % of the bulk soil's total OC and was characterized by a mixture of Al-OM complexes and imogolite-type phases, with proportions of imogolite-type phases increasing with depth. In response to the sawdust application, only the OC stock at 25-50 cm depth increased significantly (α = 0.05, 1 - β = 0.8). The increase was entirely due to increased OC in the two fractions > 1.6 g cm-3. However, there was no significant increase in the total OC stocks within the upper 100 cm. The results suggest that long-term large OC inputs cannot be taken up by the obviously OC-saturated topsoil but induce downward migration and gradually increasing storage of OC in subsurface soil layers. The small additional OC accumulation despite the extremely large OC input over 20 years, however, shows that long time periods of high input are needed to promote the downward movement and deep soil storage of OC.

The trading time risks of stock investment in stock price drop

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Tang, Nian-Sheng; Mei, Dong-Cheng; Li, Yun-Xian; Zhang, Wan

2016-11-01

This article investigates the trading time risk (TTR) of stock investment in the case of stock price drop of Dow Jones Industrial Average (ˆDJI) and Hushen300 data (CSI300), respectively. The escape time of stock price from the maximum to minimum in a data window length (DWL) is employed to measure the absolute TTR, the ratio of the escape time to data window length is defined as the relative TTR. Empirical probability density functions of the absolute and relative TTRs for the ˆDJI and CSI300 data evidence that (i) whenever the DWL increases, the absolute TTR increases, the relative TTR decreases otherwise; (ii) there is the monotonicity (or non-monotonicity) for the stability of the absolute (or relative) TTR; (iii) there is a peak distribution for shorter trading days and a two-peak distribution for longer trading days for the PDF of ratio; (iv) the trading days play an opposite role on the absolute (or relative) TTR and its stability between ˆDJI and CSI300 data.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Status of lake trout rehabilitation on Six Fathom Bank and Yankee Reef in Lake Huron

USGS Publications Warehouse

Madenjian, Charles P.; DeSorcie, Timothy J.; McClain, Jerry R.; Woldt, Aaron P.; Holuszko, Jeffrey D.; Bowen, Charles A.

2004-01-01

Six Fathom Bank, an offshore reef in the central region of Lake Huron's main basin, was stocked annually with hatchery-reared lake trout Salvelinus namaycush during 1985–1998, and nearby Yankee Reef was stocked with hatchery-reared lake trout in 1992, 1997, and annually during 1999–2001. We conducted gill-net surveys during spring and fall to evaluate performances of each of the various strains of lake trout, as well as the performance of the entire lake trout population (all strains pooled), on these two offshore reefs during 1992–2000. Criteria to evaluate performance included the proportion of “wild” fish within the population, spawner density, adult survival, growth, maturity, and wounding rate by sea lamprey Petromyzon marinus. Although naturally reproduced age-0 lake trout fry were caught on Six Fathom Bank and Yankee Reef, wild lake trout did not recruit to the adult population to any detectable degree. The density of spawning lake trout on Six Fathom Bank (>100 fish/305 m of gill net) during 1995–1998 appeared to be sufficiently high to initiate a self-sustaining population. However, annual mortality estimates for all lake trout strains pooled from catch curve analyses ranged from 0.48 to 0.62, well exceeding the target level of 0.40 suggested for lake trout rehabilitation. Annual mortality rate for the Seneca Lake strain (0.34) was significantly lower than that for the Superior–Marquette (0.69) and Lewis Lake (0.69) strains. This disparity in survival among strains was probably attributable to the lower sea-lamprey-induced mortality experienced by the Seneca Lake strain. The relatively high mortality experienced by adult lake trout partly contributed to the lack of successful natural recruitment to the adult population on these offshore reefs, but other factors were probably also involved. We recommend that both stocking of the Seneca Lake strain and enhanced efforts to reduce sea lamprey abundance in Lake Huron be continued.

Mapping the variation of soil organic carbon (SOC) stock in time and space in Sicily, an extremely variable semi-arid Mediterranean region, highlighted that C was lost in area rich in organic C and gained in poor-C areas

NASA Astrophysics Data System (ADS)

Schillaci, Calogero; Acutis, Marco; Lombardo, Luigi; Lipani, Aldo; Fantappiè, Maria; Märker, Michael; Saia, Sergio

2017-04-01

The stock of organic carbon in the soil (SOC) is an indicator of soil ability to support agro-ecosystems productivity and resilience to environmental changes (Schillaci et al. 2016; 2017). In addition, SOC stock change through space and especially time is a valuable indicator of the soil ability to sequester CO2 from the atmosphere and thus its potential to reduce the greenhouse gas effect. In the present work, we mapped (1-km resolution) the space-time variation of the SOC stock after 15 years (1993 to 2008) in a semi-arid Mediterranean area (25,286 km2) after modelling SOC concentration (0-0.4 m depth) with boosted regression trees (BRT) and computing the SOC stock after the application of the bulk density maps of ISRIC (soilgrid.com, Hengl et al., 2014). The area under study (Sicily, south of Italy) has a plenty of contrasting environments, with changing ecosystems, soils, and microclimatic regions. The BRT procedure was run with a set of 25 predictors per year, including land use, soil traits, morphometric indicators and remote sensing covariates (derived from Landsat5 data). The BRT output consisted of a high pseudo-R2(=0.71 for 1993 and 0.63 for 2008) of the SOC concentration, low uncertainty (standard deviation < 0.76 g C kg-1) and root mean square error (4.33 g SOC kg-1 in 1993 and 8.39 g SOC kg-1 in 2008). The maps of the SOC stock variation in time were produced as absolute change (t SOC ha-1 15 years-1) or percentage variation compared to the initial stock (1993). In the whole area, positive mean and median stock percentage variations were found (+10.9%±28.2% [mean±s.d.] and +8.55%, respectively). Strong SOC stock losses (-62.0% to -17.3%, corresponding to the data lower than the mean-s.d.) were found in 15.5% of the area and these pixel were mostly found in mountainous environments with high initial SOC stock and extensively used for forestry. This decrease was likely due to both high erosion rates and a short-term change in the climate, especially temperature. A high and positive percentage variation of the SOC stock (+39.1 % to +180.0%, corresponding to the data higher than the mean+s.d.) was found in 14.3% of the area under study. These environments are dominated by non-irrigated arable lands and characterized by low SOC, low rainfall and high temperature. In these conditions, the increase of the SOC stock found in 15 years likely occurred to the compulsory application of some Good Agricultural and Environmental Conditions, some of which were compulsory during the study period. Despite the mean SOC stock absolute change (and thus its percent variation) in time was positive, and the area under study corresponds to an administrative Italian region, the present results call policy to take into account of the variation of carbon at least at district level. This would allow establishing measures to protect the most vulnerable and higher SOC-stocking areas and increase the soil ability to sequester C in a view of the creation of a CO2 accounting system, with C credits and debits, at the national and European level. The increase of SOC concentration found irrespective of the land use also suggests that the agronomical measures to be favored to increase SOC should focus on agricultural aspects different from the crop and likely address to the soil and residue management. Referece: Hengl T, de Jesus JM, MacMillan RA, Batjes NH, Heuvelink GBM, et al. (2014) SoilGrids1km — Global Soil Information Based on Automated Mapping. PLoS ONE 9(8): e105992. doi:10.1371/journal.pone.0105992 Schillaci C., Saia S., Santesso M., Perego A., Brenna S., Acutis M., 2016. The importance of bioclimatic, pedology and land cover on mapping SOC stock with geostatistical approaches: the case study of the flat terrains in Po valley plain (Lombardy) agroecosystems. Proceedings of "Nuove avversità e nuovi servizi per gli Agroecosistemi" XIX Convegno Nazionale di Agrometeorologia - AIAM 2016 (Ventura F, Pieri L, eds.), pp 68-72 Bologna (BO), Italy, 14-16 June 2016 10.6092/unibo/amsacta/5164 Schillaci, C., Lombardo, L., Saia, S., Fantappiè, M., Märker, M., Acutis, M., 2017. Modelling the topsoil carbon stock of agricultural lands with the Stochastic Gradient Treeboost in a semi-arid Mediterranean region. Geoderma 286, 35-45. doi:10.1016/j.geoderma.2016.10.

Soil structure, microbial biomass and carbon and nitrogen stocks as influenced by conventional tillage and conservation techniques

NASA Astrophysics Data System (ADS)

Abrougui, Khaoula; Khemis, Chiheb; Cornelis, Wim; Chehaibi, Sayed

2017-04-01

To evaluate the impact of tillage systems on soil environment, it is necessary to quantify the modifications to physical, chemical and biological properties. The objective of this study was to evaluate the short-term impact of different tillage systems in organic farming on soil resistance to penetration, bulk density, microbial biomass, organic matter, and carbon and nitrogen stocks. The tillage systems included conventional tillage (CT), 'agronomic' tillage (AT) and superficial (shallow) tillage (ST), with ST being a non-inversion practice. Tests were carried out on alluvial poorly developed soil (10% clay, 57% silt, 33% sand) in the Higher Institute of Agronomy of Chott Meriem (Tunisia). The soil resistance to penetration was measured with a penetrologger till 50 cm depth along with soil water content measurements. Bulk density (g cm-3) was measured by a cylinder densimeter on samples collected every 10 cm till 30 cm depth. Microbial biomass is a determining factor in soil biological quality because of its role in the regulation, transformation and storage of nutrients. To count the germs, we used the method of enumeration after incorporation into agar. The Walkley and Black method was used for the determination of soil organic matter, and Kjeldahl's for the analysis of total nitrogen content. Carbon and nitrogen stocks (t ha-1) were then calculated as a function of carbon and nitrogen contents, bulk density and the horizon depth. Shallow tillage without inversion ST showed the best values in terms of soil resistance and bulk density. Indeed, soil resistance was 3.1, 2.4 and 2 MPa under CT, AT and ST respectively at 40 cm depth. By adopting this conservation technique, we noted an increase in organic matter with 53% as compared to CT (from 1.9% to 2.9%) and thus a significant increase in C (from 12.5 to 14.5 g kg-1) and N (from 5 to 8 g kg-1) stocks, particularly in the topsoil. In fact, the increase of organic matter in the topsoil constituted a reserve of essential nutrients which allowed the development and boosted the activity of living beings from 756 to 780 UFC g-1 x 105 in the topsoil as compared to CT. The overall increase of C stocks in the topsoil for ST significantly contributes to carbon sequestration.

Exploring effective sampling design for monitoring soil organic carbon in degraded Tibetan grasslands.

PubMed

Chang, Xiaofeng; Bao, Xiaoying; Wang, Shiping; Zhu, Xiaoxue; Luo, Caiyun; Zhang, Zhenhua; Wilkes, Andreas

2016-05-15

The effects of climate change and human activities on grassland degradation and soil carbon stocks have become a focus of both research and policy. However, lack of research on appropriate sampling design prevents accurate assessment of soil carbon stocks and stock changes at community and regional scales. Here, we conducted an intensive survey with 1196 sampling sites over an area of 190 km(2) of degraded alpine meadow. Compared to lightly degraded meadow, soil organic carbon (SOC) stocks in moderately, heavily and extremely degraded meadow were reduced by 11.0%, 13.5% and 17.9%, respectively. Our field survey sampling design was overly intensive to estimate SOC status with a tolerable uncertainty of 10%. Power analysis showed that the optimal sampling density to achieve the desired accuracy would be 2, 3, 5 and 7 sites per 10 km(2) for lightly, moderately, heavily and extremely degraded meadows, respectively. If a subsequent paired sampling design with the optimum sample size were performed, assuming stock change rates predicted by experimental and modeling results, we estimate that about 5-10 years would be necessary to detect expected trends in SOC in the top 20 cm soil layer. Our results highlight the utility of conducting preliminary surveys to estimate the appropriate sampling density and avoid wasting resources due to over-sampling, and to estimate the sampling interval required to detect an expected sequestration rate. Future studies will be needed to evaluate spatial and temporal patterns of SOC variability. Copyright © 2016. Published by Elsevier Ltd.

Updated analysis of flatfish recruitment response to climate variability and ocean conditions in the Eastern Bering Sea

NASA Astrophysics Data System (ADS)

Wilderbuer, Thomas; Stockhausen, William; Bond, Nicholas

2013-10-01

This study provides a retrospective analysis of the relationship between physical oceanography, biology and recruitment of three Eastern Bering Sea flatfish stocks: flathead sole (Hippoglossoides elassodon), northern rock sole (Lepidopsetta polyxystra), and arrowtooth flounder (Atheresthes stomias) during the period 1978-2005. Stock assessment model estimates of recruitment and spawning stock size indicate that temporal patterns in productivity are consistent with decadal scale (or shorter) patterns in climate variability, which may influence marine survival during the early life history phases. Density-dependence (through spawning stock size) was statistically significant in a Ricker stock-recruit model of flatfish recruitment that included environmental terms. Wind-driven advection of northern rock sole and flathead sole larvae to favorable nursery grounds was found to coincide with years of above-average recruitment. Ocean forcing of Bristol Bay surface waters during springtime was mostly on-shelf (eastward) during the 1980s and again in the early 2000s, but was off-shelf (westerly) during the 1990s, corresponding with periods of good and poor recruitment, respectively. Finally, the Arctic Oscillation was found to be an important indicator of arrowtooth flounder productivity. Model results were applied to IPCC (Intergovernmental Panel on Climate Change) future springtime wind scenarios to predict the future impact of climate on northern rock sole productivity and indicated that a moderate future increase in recruitment might be expected because the climate trends favor on-shelf transport but that density-dependence will dampen this effect such that northern rock sole abundance will not be substantially affected by climate change.

Does turbidity induced by Carassius carassius limit phytoplankton growth? A mesocosm study.

PubMed

He, Hu; Hu, En; Yu, Jinlei; Luo, Xuguang; Li, Kuanyi; Jeppesen, Erik; Liu, Zhengwen

2017-02-01

It is well established that benthivorous fish in shallow lakes can create turbid conditions that influence phytoplankton growth both positively, as a result of elevated nutrient concentration in the water column, and negatively, due to increased attenuation of light. The net effect depends upon the degree of turbidity induced by the benthivores. Stocked Carassius carassius dominate the benthivorous fish fauna in many nutrient-rich Chinese subtropical and tropical shallow lakes, but the role of the species as a potential limiting factor in phytoplankton growth is ambiguous. Clarification of this relationship will help determine the management strategy and cost of restoring eutrophic lakes in China and elsewhere. Our outdoor mesocosm experiment simulating the effect of high density of crucian carp on phytoplankton growth and community structure in eutrophic shallow lakes suggests that stocking with this species causes resuspension of sediment, thereby increasing light attenuation and elevating nutrient concentrations. However, the effect of light attenuation was insufficient to offset the impact of nutrient enhancement on phytoplankton growth, and significant increases in both phytoplankton biomass and chlorophyll a concentrations were recorded. Crucian carp stocking favored the dominance of diatoms and led to lower percentages (but not biomass) of buoyant cyanobacteria. The dominance of diatoms may be attributed to a competitive advantage of algal cells with high sedimentation velocity in an environment subjected to frequent crucian carp-induced resuspension and entrainment of benthic algae caused by the fish foraging activities. Our study demonstrates that turbidity induced by stocked crucian carp does not limit phytoplankton growth in eutrophic waters. Thus, removal of this species (and presumably other similar taxa) from subtropical or tropical shallow lakes, or suspension of aquaculture, is unlikely to boost phytoplankton growth, despite the resulting improvements in light availability.

Online Stock Market Games for High Schools.

ERIC Educational Resources Information Center

Lopus, Jane; Placone, Dennis

2002-01-01

Identifies a Web site providing information about stock market simulations for high school economics courses. Divides the information into two tables: (1) the structure of online stock market games; and (2) the determination of portfolio values of online stock market games. States that changes and updates are available at Web sites. (JEH)

Evaluating pollination deficits in pumpkin production in New York.

PubMed

Petersen, J D; Huseth, A S; Nault, B A

2014-10-01

Potential decreases in crop yield from reductions in bee-mediated pollination services threaten food production demands of a growing population. Many fruit and vegetable growers supplement their fields with bee colonies during crop bloom. The extent to which crop production requires supplementary pollination services beyond those provided by wild bees is not well documented. Pumpkin, Cucurbita pepo L., requires bee-mediated pollination for fruit development. Previous research identified the common eastern bumble bee, Bombus impatiens (Cresson), as the most efficient pumpkin pollinator. Two concomitant studies were conducted to examine pollination deficits in New York pumpkin fields from 2011 to 2013. In the first study, fruit weight, seed set, and B. impatiens visits to pumpkin flowers were compared across fields supplemented with B. impatiens colonies at a recommended stocking density of five colonies per hectare, a high density of 15 colonies per hectare, or not supplemented with bees. In the second study, fruit weight and seed set of pumpkins that received supplemental pollen through hand-pollination were compared with those that were open-pollinated by wild bees. Results indicated that supplementing pumpkin fields with B. impatiens colonies, regardless of stocking density, did not increase fruit weight, seed set, or B. impatiens visits to pumpkin flowers. Fruit weight and seed set did not differ between hand- and open-pollinated treatments. In general, we conclude that pumpkin production in central New York is not limited by inadequate pollination services provided by wild bees and that on average, supplementation with B. impatiens colonies did not improve pumpkin yield.

Effects of rearing temperature and density on growth, survival and development of sea cucumber larvae, Apostichopus japonicus (Selenka)

NASA Astrophysics Data System (ADS)

Liu, Guangbin; Yang, Hongsheng; Liu, Shilin

2010-07-01

In laboratory conditions, effects of rearing temperature and stocking density were examined on hatching of fertilized egg and growth of auricularia larvae of Apostichopus japonicus respectively. Data series like larval length and density, metamorphic time, and survival rate of the larvae were recorded. Statistics showed that for A. japonicus, survival rate (from fertilized egg to late auricularia) decreased significantly with the increasing rearing temperature ( P<0.05). At different temperatures SGR was statistically significant as well ( P<0.05) from day 1, and maximal SGR was found on day 9 at 24°C (159.26±3.28). This study clearly indicated that at low temperature (<24°C), metamorphic rate was remarkably higher than at higher temperature (>26°C). Hatching rate was significantly different between 0.2-5 ind./ml groups and 20-50 ind./ml groups. Rearing larvae at the higher density had the smaller maximal-length, whereas needed longer time to complete metamorphosis. This study suggested that 21°C and 0.4 ind./ml can be used as the most suitable rearing temperature and stocking density for large -scale artificial breeding of A. japonicus’s larvae.

The dynamics of a fish stock exploited in two fishing zones.

PubMed

Mchich, R; Auger, P; Raïss, N

2000-12-01

This work presents a specific stock-effort dynamical model. The stocks correspond to two populations of fish moving and growing between two fishery zones. They are harvested by two different fleets. The effort represents the number of fishing boats of the two fleets that operate in the two fishing zones. The bioeconomical model is a set of four ODE's governing the fishing efforts and the stocks in the two fishing areas. Furthermore, the migration of the fish between the two patches is assumed to be faster than the growth of the harvested stock. The displacement of the fleets is also faster than the variation in the number of fishing boats resulting from the investment of the fishing income. So, there are two time scales: a fast one corresponding to the migration between the two patches, and a slow time scale corresponding to growth. We use aggregation methods that allow us to reduce the dimension of the model and to obtain an aggregated model for the total fishing effort and fish stock of the two fishing zones. The mathematical analysis of the model is shown. Under some conditions, we obtain a stable equilibrium, which is a desired situation, as it leads to a sustainable harvesting equilibrium, keeping the stock at exploitable densities.

Trial finds biomass harvest of cobia unaffected by stocking density in RAS

USDA-ARS?s Scientific Manuscript database

Cobia, Rachycentron canadum, were reared for 119 days from 322 g to market size in production-scale recirculating aquaculture systems at in-tank densities of 10, 20, or 30 kg/m3. No significant differences were detected in growth rate, survival, feed efficiency or body composition. This study is t...

Changes in carbon stock associated with post-settlement wetland conversion in Southern Ontario, Canada, and implications for Holocene carbon dynamics

NASA Astrophysics Data System (ADS)

Byun, E.; Finkelstein, S. A.; Cowling, S. A.; Badiou, P.

2017-12-01

Organic matter accumulation often exceeds total respiration in wetlands, which makes them a sink in the global carbon cycle. Efforts are ongoing to inventory global wetland carbon stocks, but there remain non-negligible uncertainties for the present day as well as for the Holocene. Recent work compiling regional data for global-scale estimations is likely to be conservative as there are still poorly evaluated sites. In temperate regions, wetland conversion for other land uses has been so prevalent that accurate estimates of the extent of natural wetlands prior to disturbance have been difficult to achieve. Most studies of long-term peat carbon accumulation address boreal/subarctic bogs and fens, and more recently, tropical peat swamps. Temperate swamps and marshes are often categorized as non-peat forming wetlands and have not been explicitly considered in Holocene carbon storage. This study aims to reassess wetlands in southern Ontario as an example of an underestimated organic carbon stock. By combining two wetland maps, one for pre-settlement (before 1850 AD) extent and the other for current land cover, pre-settlement wetland cover was reconstructed and assigned to one of five wetland classes (bog, fen, tree/shrub swamp, and marsh). Carbon density for each wetland class was obtained from a peatland inventory for southeastern Ontario, including peat core data from swamp and marsh sites. Potential organic carbon stock in each wetland class was quantified by the product of the extent and the carbon density, resulting in an estimate of 3.3 PgC for pre-settlement wetlands in the study area, and 1.3 PgC stored in present-day wetlands. The difference gives 2 PgC loss for the past 150 years, but this represents a maximum potential as 56-81% of the original wetlands were converted to croplands that will retain some carbon. This study highlights the importance of temperate wetlands not included in syntheses of global peatland carbon over the Holocene. Southern Ontario is only a part of the enormous landmass in the temperate Northern Hemisphere, which suggests potentially high carbon storage when scaling up globally. Future work is needed to better quantify all the potential wetland carbon through more studies of organic carbon stocks in swamps and marshes, the most common wetland types in this region of the temperate zone.

Impacts of airborne lidar pulse density on estimating biomass stocks and changes in a selectively logged tropical forest

Treesearch

Carlos Alberto Silva; Andrew Thomas Hudak; Lee Alexander Vierling; Carine Klauberg; Mariano Garcia; Antonio Ferraz; Michael Keller; Jan Eitel; Sassan Saatchi

2017-01-01

Airborne lidar has become a well-suited technology for predicting and mapping many tropical forest attributes, including aboveground biomass (AGB). However, trade-offs exist between lidar pulse density and acquisition cost. The aim of this study was to evaluate the influence of lidar pulse density on AGB change predictions using airborne lidar and field plot data in a...

Large Differences in Global and Regional Total Soil Carbon Stock Estimates Based on SoilGrids, HWSD, and NCSCD: Intercomparison and Evaluation Based on Field Data From USA, England, Wales, and France

NASA Astrophysics Data System (ADS)

Tifafi, Marwa; Guenet, Bertrand; Hatté, Christine

2018-01-01

Soils are the major component of the terrestrial ecosystem and the largest organic carbon reservoir on Earth. However, they are a nonrenewable natural resource and especially reactive to human disturbance and climate change. Despite its importance, soil carbon dynamics is an important source of uncertainty for future climate predictions and there is a growing need for more precise information to better understand the mechanisms controlling soil carbon dynamics and better constrain Earth system models. The aim of our work is to compare soil organic carbon stocks given by different global and regional databases that already exist. We calculated global and regional soil carbon stocks at 1 m depth given by three existing databases (SoilGrids, the Harmonized World Soil Database, and the Northern Circumpolar Soil Carbon Database). We observed that total stocks predicted by each product differ greatly: it is estimated to be around 3,400 Pg by SoilGrids and is about 2,500 Pg according to Harmonized World Soil Database. This difference is marked in particular for boreal regions where differences can be related to high disparities in soil organic carbon concentration. Differences in other regions are more limited and may be related to differences in bulk density estimates. Finally, evaluation of the three data sets versus ground truth data shows that (i) there is a significant difference in spatial patterns between ground truth data and compared data sets and that (ii) data sets underestimate by more than 40% the soil organic carbon stock compared to field data.

Results of the second national forest soil inventory in Germany - Interpretation of level and stock profiles for PCDD/F and PCB in terms of vegetation and humus type.

PubMed

Pandelova, Marchela; Henkelmann, Bernhard; Bussian, Bernd M; Schramm, Karl-Werner

2018-01-01

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were detected in 86 humic topsoil layers and in a subset of 11 randomly selected top mineral forest soils at the depths of 0-5cm and 5-10cm collected from different federal states of Germany. The distribution of these persistent organic pollutants (POPs) in humic topsoils with respect to vegetation cover (coniferous vs. deciduous vs. mixed), total organic carbon (TOC), altitude and latitude data was investigated. There is cross correlation between the contents and TOC while the correlation with latitude indicates higher abundances of POPs in central Germany where there is high population density accompanied with industrial activities. The calculated stocks suggest that humus type (mor, mull, or moder) in conjunction with forest type can explain the relative POPs abundances in different soil layers. Generally, humic topsoils show highest contents of POPs compare to the two mineral soils with a ratio of 100:10:1. However, the stock humic layers of coniferous stands contribute about 50% to the total stock, whereas at deciduous stands the stock is mainly located in the upper mineral soil layer (0-5cm). The soil-water distribution coefficients (Kd) were calculated to estimate the potential translocation in the different soil types. The Kd values vary among the PCBs and PCDD/Fs congeners and are most variable for humic topsoils. There is pronounced chemical abundance in the top mineral soils with increasing Kd and this points to non-water bound transport processes for superlipophilic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Variety and volatility in financial markets

NASA Astrophysics Data System (ADS)

Lillo, Fabrizio; Mantegna, Rosario N.

2000-11-01

We study the price dynamics of stocks traded in a financial market by considering the statistical properties of both a single time series and an ensemble of stocks traded simultaneously. We use the n stocks traded on the New York Stock Exchange to form a statistical ensemble of daily stock returns. For each trading day of our database, we study the ensemble return distribution. We find that a typical ensemble return distribution exists in most of the trading days with the exception of crash and rally days and of the days following these extreme events. We analyze each ensemble return distribution by extracting its first two central moments. We observe that these moments fluctuate in time and are stochastic processes, themselves. We characterize the statistical properties of ensemble return distribution central moments by investigating their probability density functions and temporal correlation properties. In general, time-averaged and portfolio-averaged price returns have different statistical properties. We infer from these differences information about the relative strength of correlation between stocks and between different trading days. Last, we compare our empirical results with those predicted by the single-index model and we conclude that this simple model cannot explain the statistical properties of the second moment of the ensemble return distribution.

Use of fish species from different trophic levels to control algae and water quality: An enclosure experiment in eutrophic area of Xiaojiang River.

PubMed

Hu, Lian; Yang, Zhi; Pan, Xiaojie; Zhao, Na; Peng, Jianhua; Wan, Chengyan

2017-01-01

The effects of stocking both filter-feeding fish and piscivorous fish were compared to the effects of stocking only filter-feeding fish for suppressing algal blooms and improving water quality in the impoundment area of Xiaojiang River where catfish were dominant. Using only filter-feeding fish for algal suppression and water quality control was more effective in the short-term, but use of both filter-feeding fish and piscivorous fish was better in the long-term. Obvious suppression of phytoplankton biomass (PB) only occurred during the first 14 days regardless of the fish stocked. Adding fish to the enclosure clearly alters phytoplankton community structure and introducing piscivorous fish to an enclosure stocked with filter-feeding fish changed the relative densities of dominant algae species. While stocking filter-feeding fish decreased total nitrogen concentration by removing phytoplankton, it did not effectively decrease total phosphorus and Chlorophyll a concentrations. Introducing piscivorous fish to the enclosure weakened the relationship between nutrients and phytoplankton. Results indicate that stocking only filter-feeding fish to improve water quality and suppress phytoplankton in an impoundment area is insufficient and other technologies and means should be applied simultaneously.

Intraspecific competition and density dependence of food consumption and growth in Arctic charr.

PubMed

Amundsen, Per-Arne; Knudsen, Rune; Klemetsen, Anders

2007-01-01

1. Intraspecific competition for restricted food resources is considered to play a fundamental part in density dependence of somatic growth and other population characteristics, but studies simultaneously addressing the interrelationships between population density, food acquisition and somatic growth have been missing. 2. We explored the food consumption and individual growth rates of Arctic charr Salvelinus alpinus in a long-term survey following a large-scale density manipulation experiment in a subarctic lake. 3. Prior to the initiation of the experiment, the population density was high and the somatic growth rates low, revealing a severely overcrowded and stunted fish population. 4. During the 6-year period of stock depletion the population density of Arctic charr was reduced with about 75%, resulting in an almost twofold increase in food consumption rates and enhanced individual growth rates of the fish. 5. Over the decade following the density manipulation experiment, the population density gradually rose to intermediate levels, accompanied by corresponding reductions in food consumption and somatic growth rates. 6. The study revealed negative relationships with population density for both food consumption and individual growth rates, reflecting a strong positive correlation between quantitative food intake and somatic growth rates. 7. Both the growth and consumption rate relationships with population density were well described by negative power curves, suggesting that large density perturbations are necessary to induce improved feeding conditions and growth rates in stunted fish populations. 8. The findings demonstrate that quantitative food consumption represents the connective link between population density and individual growth rates, apparently being highly influenced by intraspecific competition for limited resources.

Arbitrage and Volatility in Chinese Stock's Markets

NASA Astrophysics Data System (ADS)

Lu, Shu Quan; Ito, Takao; Zhang, Jianbo

From the point of view of no-arbitrage pricing, what matters is how much volatility the stock has, for volatility measures the amount of profit that can be made from shorting stocks and purchasing options. With the short-sales constraints or in the absence of options, however, high volatility is likely to mean arbitrage from stock market. As emerging stock markets for China, investors are increasingly concerned about volatilities of Chinese two stock markets. We estimate volatility's models for Chinese stock markets' indexes using Markov chain Monte Carlo (MCMC) method and GARCH. We find that estimated values of volatility parameters are very high for all data frequencies. It suggests that stock returns are extremely volatile even at long term intervals in Chinese markets. Furthermore, this result could be considered that there seems to be arbitrage opportunities in Chinese stock markets.

Cluster Analysis and Gaussian Mixture Estimation of Correlated Time-Series by Means of Multi-dimensional Scaling

NASA Astrophysics Data System (ADS)

Ibuki, Takero; Suzuki, Sei; Inoue, Jun-ichi

We investigate cross-correlations between typical Japanese stocks collected through Yahoo!Japan website ( http://finance.yahoo.co.jp/ ). By making use of multi-dimensional scaling (MDS) for the cross-correlation matrices, we draw two-dimensional scattered plots in which each point corresponds to each stock. To make a clustering for these data plots, we utilize the mixture of Gaussians to fit the data set to several Gaussian densities. By minimizing the so-called Akaike Information Criterion (AIC) with respect to parameters in the mixture, we attempt to specify the best possible mixture of Gaussians. It might be naturally assumed that all the two-dimensional data points of stocks shrink into a single small region when some economic crisis takes place. The justification of this assumption is numerically checked for the empirical Japanese stock data, for instance, those around 11 March 2011.

Impact of cage stocking density on egg laying characteristics and related stress and immunity parameters of Japanese quails in subtropics.

PubMed

El-Tarabany, M S

2016-10-01

The aim of this study was to investigate the effects of different cage stocking densities on egg production parameters, as well as related stress and immunity indices in Japanese quails under subtropical Egyptian conditions. Two hundred and sixteen birds of Japanese quail at 14th week of age were used in this experiment. The birds were divided randomly into three groups: 60, 72 and 84. Each group subdivided into 4 replicates, where the cages' floor spaces were 200 (S1 ), 167 (S2 ) and 143 (S3 ) cm(2) /bird, respectively. Birds housed at 200 cm(2) /bird (S1 ) had superior fertility (fertility % (p = 0.013) and hatchability % (p = 0.041)), egg production (egg weight (p = 0.034) and egg mass (p = 0.001)) and immunity parameters (higher geometric mean of antibody titres against Newcastle disease virus, p = 0.024). Furthermore, they had higher internal egg quality score: albumen height (p = 0.003), yolk height (p = 0.023), yolk index (p = 0.006) and Haugh unit (p = 0.035). Birds housed at 143 cm(2) /bird (S3 ) had the lowest total leucocytic count and lymphocyte % (p = 0.022), but the highest H/L ratio (p = 0.001). Corticosterone concentration was lower in S1 group (p = 0.031) than that in groups housed at higher densities. Japanese quail housed at high densities revealed drop in fertility, hatchability, production and immunity parameters, indicating a detrimental effects on both welfare and economic income. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

Short- and long-term effects of fire on carbon in US dry temperate forest systems

USGS Publications Warehouse

Hurteau, Matthew D.; Brooks, Matthew L.

2011-01-01

Forests sequester carbon from the atmosphere, and in so doing can mitigate the effects of climate change. Fire is a natural disturbance process in many forest systems that releases carbon back to the atmosphere. In dry temperate forests, fires historically burned with greater frequency and lower severity than they do today. Frequent fires consumed fuels on the forest floor and maintained open stand structures. Fire suppression has resulted in increased understory fuel loads and tree density; a change in structure that has caused a shift from low- to high-severity fires. More severe fires, resulting in greater tree mortality, have caused a decrease in forest carbon stability. Fire management actions can mitigate the risk of high-severity fires, but these actions often require a trade-off between maximizing carbon stocks and carbon stability. We discuss the effects of fire on forest carbon stocks and recommend that managing forests on the basis of their specific ecologies should be the foremost goal, with carbon sequestration being an ancillary benefit. ?? 2011 by American Institute of Biological Sciences. All rights reserved.

Limitations to lake trout (Salvelinus namaycush) rehabilitation in the Great Lakes imposed by biotic interactions occurring at early life stages

USGS Publications Warehouse

Jones, Michael L.; Eck, Gary W.; Evans, David O.; Fabrizio, Mary C.; Hoff, Michael H.; Hudson, Patrick L.; Janssen, John; Jude, David; O'Gorman, Robert; Savino, Jacqueline F.

1995-01-01

We examine evidence that biotic factors, particularly predation, may be limiting early survival of wild lake trout (Salvelinus namaycush) juveniles in many areas of the Great Lakes. The Great Lakes contain numerous potential predators of lake trout eggs and fry, some of which are recent invaders, and most of which were probably absent when lake trout most recently re-invaded the Great Lakes after the last ice age. Simple quantitative models of predation suggest that plausible assumptions about prey densities, predator feeding rates, and duration of exposure of predator to prey can lead to very high estimates of predation mortality, in some instances approaching 100%. Indirect evidence from inter-Great Lake comparisons and inland lake examples also suggest that biotic factors may impede successful lake trout colonization. Our synthesis of the evidence leads to recommendations for research to better define field feeding rates of lake trout egg and fry predators and comparative studies of densities of potential egg and fry predators on lake trout spawning reefs. Management options should be designed to provide useful information as well as achieve short-term goals. From a management standpoint we recommend that: newly constructed lake trout reefs should be placed well away from concentrations of potential predators; offshore spawning reefs should be stocked; salmonine stocking, nutrient abatement, and commercial harvest of alewives should all be considered as options to enhance survival of young lake trout; hatchery lake trout should not be stocked at sites where wild lake trout are showing signs of recovery; and exotic species expansions or introductions must be curtailed to maintain or improve on our recent successes in lake trout rehabilitation.

Biomass carbon stocks in China's forests between 2000 and 2050: a prediction based on forest biomass-age relationships.

PubMed

Xu, Bing; Guo, ZhaoDi; Piao, ShiLong; Fang, JingYun

2010-07-01

China's forests are characterized by young forest age, low carbon density and a large area of planted forests, and thus have high potential to act as carbon sinks in the future. Using China's national forest inventory data during 1994-1998 and 1999-2003, and direct field measurements, we investigated the relationships between forest biomass density and forest age for 36 major forest types. Statistical approaches and the predicted future forest area from the national forestry development plan were applied to estimate the potential of forest biomass carbon storage in China during 2000-2050. Under an assumption of continuous natural forest growth, China's existing forest biomass carbon (C) stock would increase from 5.86 Pg C (1 Pg=10(15) g) in 1999-2003 to 10.23 Pg C in 2050, resulting in a total increase of 4.37 Pg C. Newly planted forests through afforestation and reforestation will sequestrate an additional 2.86 Pg C in biomass. Overall, China's forests will potentially act as a carbon sink for 7.23 Pg C during the period 2000-2050, with an average carbon sink of 0.14 Pg C yr(-1). This suggests that China's forests will be a significant carbon sink in the next 50 years.

Characterizing bacterial communities in tilapia pond surface sediment and their responses to pond differences and temporal variations.

PubMed

Fan, Limin; Barry, Kamira; Hu, Gengdong; Meng, Shunlong; Song, Chao; Qiu, Liping; Zheng, Yao; Wu, Wei; Qu, Jianhong; Chen, Jiazhang; Xu, Pao

2017-01-01

Bacterial community compositions in the surface sediment of tilapia ponds and their responses to pond characteristics or seasonal variations were investigated. For that, three ponds with different stocking densities were selected to collect the samples. And the method of Illumina high-throughput sequencing was used to amplify the bacterial 16S rRNA genes. A total of 662, 876 valid reads and 5649 operational taxonomic units were obtained. Further analysis showed that the dominant phyla in all three ponds were Proteobacteria, Bacteroidetes, Chloroflexi, and Acidobacteria. The phyla Planctomycetes, Firmicutes, Chlorobi, and Spirochaetae were also relatively abundant. Among the eight phyla, the abundances of only Proteobacteria, Bacteroidetes, Firmicutes, and Spirochaetae were affected by seasonal variations, while seven of these (with the exception of Acidobacteria) were affected by pond differences. A comprehensive analysis of the richness and diversity of the bacterial 16S rRNA gene, and of the similarity in bacterial community composition in sediment also showed that the communities in tilapia pond sediment were shaped more by pond differences than by seasonal variations. Linear discriminant analysis further indicated that the influences of pond characteristics on sediment bacterial communities might be related to feed coefficients and stocking densities of genetically improved farmed tilapia (GIFT).

Diet of juvenile burbot and insight on gape limitation

USGS Publications Warehouse

Klein, Zachary B.; Hardy, Ryan S.; Quist, Michael C.

2016-01-01

Throughout much of their distribution, Burbot (Lota lota ) populations are declining or have been extirpated. Burbot in the Kootenai River, Idaho represent one such imperiled population. In an effort to restore Burbot in the Kootenai River, managers have turned to conservation aquaculture. However, no appreciable increase in natural recruitment has been observed in the system. The lack of natural recruitment is believed to be partly due to a deficiency of high-quality prey. As a result, we sought to i) describe the diet of juvenile Burbot, ii) evaluate the influence of Burbot mouth gape on diet and iii) estimate prey availability at release locations. Burbot were stocked into two earthen ponds at the Boundary Creek Wildlife Management Area (BCWMA) and sampled weekly to evaluate diet. Zooplankton were sampled weekly from each pond and from release locations of hatchery-reared Burbot (i.e., Kootenai River, Goat River, Boundary Creek, Deep Creek) to quantify prey availability. Over the course of the study (~3 months), Burbot primarily fed on Cyclopoida. Burbot never appeared to be gape limited and exhibited little variability in the size of zooplankton ingested. Zooplankton densities at stocking locations were relatively low in comparison to BCWMA ponds. Low zooplankton densities at release sites indicate that alternative management actions may need to be considered to enhance Burbot recruitment in the Kootenai River drainage.

Interactive effects of high stocking density and food deprivation on carbohydrate metabolism in several tissues of gilthead sea bream Sparus auratus.

PubMed

Sangiao-Alvarellos, Susana; Guzmán, José M; Láiz-Carrión, Raúl; Míguez, Jesús M; Martín Del Río, María P; Mancera, Juan M; Soengas, José L

2005-09-01

The influence of high stocking density (HSD) and food deprivation was assessed on carbohydrate metabolism of several tissues of gilthead sea bream Sparus auratus for 14 days. Fish were randomly assigned to one of four treatments: (1) fed fish under normal stocking density (NSD) (4 kg m(-3)); (2) fed fish under HSD (70 kg m(-3)); (3) food-deprived fish under NSD; and (4) food-deprived fish under HSD. After 14 days, samples were taken from the plasma, liver, gills, kidney and brain for the assessment of plasma cortisol, levels of metabolites and the activity of several enzymes involved in carbohydrate metabolism. HSD conditions alone elicited important changes in energy metabolism of several tissues that in some cases were confirmatory (5-fold increase in plama cortisol, 20% increase in plasma glucose, 60% decrease in liver glycogen and 20% increase in gluconeogenic potential in the liver) whereas in others provided new information regarding metabolic adjustments to cope with HSD in the liver (100% increase in glucose phosphorylating capacity), gills (30% decrease in capacity for phosphorylating glucose), kidney (80% increase in the capacity of phosphorylating glucose) and brain (2.5-fold increase in ATP levels). On the other hand, food deprivation alone resulted in increased plasma cortisol, and metabolic changes in the liver (enhanced gluconeogenic and glycogenolytic potential of 13% and 18%, respectively) and brain (10% increase in glycolytic capacity), confirmatory of previous studies, whereas new information regarding metabolic adjustments during food deprivation was obtained in the gills and kidney (decreased lactate levels in both tissues of 45% and 55%, respectively). Furthermore, the results obtained provided, for the first time in fish, information indicating that food deprivation increased the sensitivity of gilthead sea bream to the stress induced by HSD compared with the fed controls, as demonstrated by increased plasma cortisol levels (50% increase vs. fed fish) and a further increase in the capacity to export glucose mobilized from liver glycogen stores (70% decrease vs. fed fish). These results lend support for a cumulative effect of both stressors on plasma cortisol and parameters assessed on carbohydrate metabolism in the present experiments, and provide information regarding reallocation of metabolic energy to cope with simultaneous stressors in fish. (c) 2005 Wiley-Liss, Inc.

Cryptosporidiosis Risk in New Zealand Children Under 5 Years Old is Greatest in Areas with High Dairy Cattle Densities.

PubMed

Lal, Aparna; Dobbins, Timothy; Bagheri, Nasser; Baker, Michael G; French, Nigel P; Hales, Simon

2016-12-01

The public health risks associated with dairy farming intensification are an emerging concern. We examine the association between dairy cattle density and cryptosporidiosis risk in children <5 years old in New Zealand from 1997 to 2008, a period of rapid intensification of the dairy industry. Multi-level Poisson regression was used to model reported cryptosporidiosis (N = 3869 cases) incidence in relation to dairy cattle densities across urban and rural areas separately, after controlling for microbiological quality of public drinking water supplies and neighbourhood socio-economic factors using the Census Area Unit of residence. Within urban areas, the risk of cryptosporidiosis in children less than 5 years old was significantly, positively associated with medium and high dairy cattle density IRR 1.3 (95% CI 1.2, 1.5) and 1.5 (95% CI 1.2, 1.9) respectively, when compared to areas with no dairy cattle. Within rural areas, the incidence risk of cryptosporidiosis in children less than 5 years old were significantly, positively associated with medium and high dairy cattle density: IRR 1.7 (95% CI 1.3, 2.3) and 2.0 (95% CI 1.5, 2.8) respectively, when compared to areas with no dairy cattle. These results have public health implications for children living on and in proximity to intensively stocked dairy cattle farms.

Deadwood stocks increase with selective logging and large tree frequency in Gabon.

PubMed

Carlson, Ben S; Koerner, Sally E; Medjibe, Vincent P; White, Lee J T; Poulsen, John R

2017-04-01

Deadwood is a major component of aboveground biomass (AGB) in tropical forests and is important as habitat and for nutrient cycling and carbon storage. With deforestation and degradation taking place throughout the tropics, improved understanding of the magnitude and spatial variation in deadwood is vital for the development of regional and global carbon budgets. However, this potentially important carbon pool is poorly quantified in Afrotropical forests and the regional drivers of deadwood stocks are unknown. In the first large-scale study of deadwood in Central Africa, we quantified stocks in 47 forest sites across Gabon and evaluated the effects of disturbance (logging), forest structure variables (live AGB, wood density, abundance of large trees), and abiotic variables (temperature, precipitation, seasonality). Average deadwood stocks (measured as necromass, the biomass of deadwood) were 65 Mg ha -1 or 23% of live AGB. Deadwood stocks varied spatially with disturbance and forest structure, but not abiotic variables. Deadwood stocks increased significantly with logging (+38 Mg ha -1 ) and the abundance of large trees (+2.4 Mg ha -1 for every tree >60 cm dbh). Gabon holds 0.74 Pg C, or 21% of total aboveground carbon in deadwood, a threefold increase over previous estimates. Importantly, deadwood densities in Gabon are comparable to those in the Neotropics and respond similarly to logging, but represent a lower proportion of live AGB (median of 18% in Gabon compared to 26% in the Neotropics). In forest carbon accounting, necromass is often assumed to be a constant proportion (9%) of biomass, but in humid tropical forests this ratio varies from 2% in undisturbed forest to 300% in logged forest. Because logging significantly increases the deadwood carbon pool, estimates of tropical forest carbon should at a minimum use different ratios for logged (mean of 30%) and unlogged forests (mean of 18%). © 2016 John Wiley & Sons Ltd.

Density-dependent effects of omnivorous stream crayfish on benthic trophic dynamics

USGS Publications Warehouse

Ludlam, J.P.; Banks, B. T.; Magoulick, Daniel D.

2015-01-01

Crayfish are abundant and important consumers in aquatic food webs and crayfish invasions have demonstrated strong effects of crayfish on multiple trophic levels. Density may be an important factor determining the role of omnivorous crayfish in benthic communities, especially if density alters the strength of trophic interactions. The effect of crayfish density on a simple benthic food web using ceramic tiles was examined in three treatments (crayfish exclusion cage, cage control (open to crayfish), and exposed ceramic tiles) in mesocosms stocked with 6, 12, or 18 crayfish·m-2. We hypothesized that at low densities crayfish consumption of herbivorous chironomids would increase algal abundance, but at high densities crayfish would reduce both periphyton and invertebrates. In the experiment, periphyton and chironomid abundance increased with declining crayfish biomass on day 30 but not day 15. The magnitude of crayfish effects on day 15 periphyton chlorophyll a abundance increased with crayfish biomass, but crayfish effects on day 30 periphyton chlorophyll a or chironomid biomass did not increase with crayfish biomass. In this experiment there was little evidence for a trophic cascade at low crayfish densities and strong omnivory by crayfish dominated trophic dynamics.

The returns and risks of investment portfolio in stock market crashes

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Long, Chao; Chen, Xiao-Dan

2015-06-01

The returns and risks of investment portfolio in stock market crashes are investigated by considering a theoretical model, based on a modified Heston model with a cubic nonlinearity, proposed by Spagnolo and Valenti. Through numerically simulating probability density function of returns and the mean escape time of the model, the results indicate that: (i) the maximum stability of returns is associated with the maximum dispersion of investment portfolio and an optimal stop-loss position; (ii) the maximum risks are related with a worst dispersion of investment portfolio and the risks of investment portfolio are enhanced by increasing stop-loss position. In addition, the good agreements between the theoretical result and real market data are found in the behaviors of the probability density function and the mean escape time.

Lake trout restoration in the Great Lakes: stock-size criteria for natural reproduction

USGS Publications Warehouse

Selgeby, James H.; Bronte, Charles R.; Brown, Edward H.; Hansen, Michael J.; Holey, Mark E.; VanAmberg, Jan P.; Muth, Kenneth M.; Makauskas, Daniel B.; Mckee, Patrick; Anderson, David M.; Ferreri, C. Paola; Schram, Stephen T.

1995-01-01

We examined the question of whether the lake trout restoration program in the Great Lakes has developed brood stocks of adequate size to sustain natural reproduction. Stock size criteria were developed from areas of the Great Lakes where natural reproduction has been successful (defined as detection of age-1 or older recruits by assessment fishing). We contrasted them with stocks in areas with no natural reproduction. Based on the relative abundance of spawners measured in the fall and the presence or absence of natural reproduction in 24 areas of the Great Lakes, we found three distinct sets of lake trout populations. In seven areas of successful natural reproduction, the catch-per-unit-effort (CPE) of spawners ranged from 17 to 135 fish/305 m of gillnet. Stock sizes in these areas were used as a gauge against which stocks in other areas were contrasted. We conclude that stock densities of 17-135 fish/305 m of gill net are adequate for natural reproduction, provided that all other requirements are met. No natural reproduction has been detected in seven other areas, where CPEs of spawners ranged from only 3 to 5 fish/305 m. We conclude that spawning stocks of only 3-5 fish/305 m of net are inadequate to develop measurable natural reproduction. Natural reproduction has also not been detected in ten areas where CPEs of spawners ranged from 43 to 195 fish/305 m of net. We conclude that spawning stocks in these ten areas were adequate to sustain natural reproduction, but that some factor other than parental stock size prevented recruitment of wild lake trout.

Importance of Seedyear, Seedbed, and Overstory for Establishment of Natural Loblolly and Shortleaf Pine Regenerationin Southern Arkansas

Treesearch

Michael D. Cain

1991-01-01

First-year density and quadrat stocking of naturally established loblolly and shortleaf pine regeneration were monitored forfive consecutive seedyearson disturbed and undisturbed seedbeds. Compared to untreatedchecks,additional gainsin pine seedling density as a result of exposing mineral soil were not as great as initial gains achieved by control of overtopping...

Wood-based panel plant locations and timber availability in selected U.S. states

Treesearch

T. McKeever; H. N. Spelter

1998-01-01

This report lists wood-based panel industry plant locations, production capacities, timber inventories, and wood costs for 24 U.S. states. Industry sectors covered include medium-density fiberboard, particleboard, softwood plywood, and oriented strandboard. Maps of major forest producing states show plant locations and the underlying density of timber stocking by...

A conceptual model of the controlling factors of soil organic carbon and nitrogen densities in a permafrost-affected region on the eastern Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Smoak, Joseph M.; Li, Wangping; Shi, Wei; Sheng, Yu; Zhao, Lin; Ding, Yongjian

2017-07-01

Many investigations of the preservation of soil organic carbon (SOC) in permafrost regions have examined roles of geomorphology, pedogenesis, vegetation cover, and permafrost within particular regions. However, it is difficult to disentangle the effects of multiple factors on the SOC in permafrost regions due to the heterogeneity in environmental conditions. Based on data from 73 soil study sites in permafrost regions of the eastern Qinghai-Tibetan Plateau, we developed a simple conceptual model, which relates SOC to topography, vegetation, and pedogenesis. We summarized the dominant factors and their controls on SOC using 31 measured soil physiochemical variables. Soil texture explains approximately 60% of the variations in the SOC stocks for the upper 0-2 m soil. Soil particle size closely correlates to soil moisture, which is an important determinant of SOC. Soil salinity and cations are important factors as well and can explain about 10% of the variations in SOC. The SOC and total nitrogen (TN) stocks for the 1-2 m depths have larger uncertainties than those of upper 1 m soil layer. The vegetation, pH, and bulk density mainly affects SOC and TN stocks for the upper 1 m soil layers, while the active layer thickness and soil particle size have greater influence on SOC and TN stocks for the 1-2 m soils. Our results suggest that the soil particle size is the most important controller of SOC pools, and the stocks of SOC and TN are strongly effected by soil development processes in the permafrost regions of the eastern Qinghai-Tibetan Plateau.

Global distribution of soil organic carbon, based on the Harmonized World Soil Database - Part 1: Masses and frequency distribution of SOC stocks for the tropics, permafrost regions, wetlands, and the world

NASA Astrophysics Data System (ADS)

Köchy, M.; Hiederer, R.; Freibauer, A.

2014-09-01

The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget. We review current estimates of soil organic carbon stocks (mass/area) and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg. Correcting the HWSD's bulk density of organic soils, especially Histosols, results in a mass of 1062 Pg. The uncertainty of bulk density of Histosols alone introduces a range of -56 to +180 Pg for the estimate of global SOC in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arc minutes, the areal masses of SOC and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. Incorporating more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Data Base (496 Pg SOC) and tropical peatland carbon, global soils contain 1324 Pg SOC in the upper 1 m including 421 Pg in tropical soils, whereof 40 Pg occur in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

Soil organic carbon sequestration potential of conservation vs. conventional tillage

NASA Astrophysics Data System (ADS)

Meurer, Katharina H. E.; Ghafoor, Abdul; Haddaway, Neal R.; Bolinder, Martin A.; Kätterer, Thomas

2017-04-01

Soil tillage has been associated with many negative impacts on soil quality, especially a reduction in soil organic carbon (SOC). The benefits of no tillage (NT) on topsoil SOC concentrations have been demonstrated in several reviews, but the effect of reduced tillage (RT) compared to conventional tillage (CT) that usually involves soil inversion through moldboard ploughing is still unclear. Moreover, the effect of tillage on total SOC stocks including deeper layers is still a matter of considerable debate, because the assessment depends on many factors such as depth and method of measurement, cropping systems, soil type, climatic conditions, and length of the experiments used for the analysis. From a recently published systematic map database consisting of 735 long-term field experiments (≥ 10 years) within the boreal and temperate climate zones (Haddaway et al. 2015; Environmental Evidence 4:23), we selected all tillage studies (about 80) reporting SOC concentrations along with dry soil bulk density and conducted a systematic review. SOC stocks were calculated considering both fixed soil depths and by using the concept of equivalent soil mass. A meta-analysis was used to determine the influence of environmental, management, and soil-related factors regarding their prediction potential on SOC stock changes between the tillage categories NT, RT, and CT. C concentrations and stocks to a certain depth were generally highest under NT, intermediate under RT, and lowest under CT. However, this effect was mainly limited to the first 15 cm and disappeared or was even reversed in deeper layers, especially when adjusting soil depth according to the equivalent soil mineral mass. Our study highlights the impact of tillage-induced changes in soil bulk density between treatments and shows that neglecting the principles of equivalent soil mass leads to overestimation of SOC stocks for by conservation tillage practices.

Pattern variation of fish fingerling abundance in the Na Thap Tidal river of Southern Thailand: 2005-2015

NASA Astrophysics Data System (ADS)

Donroman, T.; Chesoh, S.; Lim, A.

2018-04-01

This study aimed to investigate the variation patterns of fish fingerling abundance based on month, year and sampling site. Monthly collecting data set of the Na Thap tidal river of southern Thailand, were obtained from June 2005 to October 2015. The square root transformation was employed for maintaining the fingerling data normality. Factor analysis was applied for clustering number of fingerling species and multiple linear regression was used to examine the association between fingerling density and year, month and site. Results from factor analysis classified fingerling into 3 factors based on saline preference; saline water, freshwater and ubiquitous species. The results showed a statistically high significant relation between fingerling density, month, year and site. Abundance of saline water and ubiquitous fingerling density showed similar pattern. Downstream site presented highest fingerling density whereas almost of freshwater fingerling occurred in upstream. This finding confirmed that factor analysis and the general linear regression method can be used as an effective tool for predicting and monitoring wild fingerling density in order to sustain fish stock management.

Can we estimate molluscan abundance and biomass on the continental shelf?

NASA Astrophysics Data System (ADS)

Powell, Eric N.; Mann, Roger; Ashton-Alcox, Kathryn A.; Kuykendall, Kelsey M.; Chase Long, M.

2017-11-01

Few empirical studies have focused on the effect of sample density on the estimate of abundance of the dominant carbonate-producing fauna of the continental shelf. Here, we present such a study and consider the implications of suboptimal sampling design on estimates of abundance and size-frequency distribution. We focus on a principal carbonate producer of the U.S. Atlantic continental shelf, the Atlantic surfclam, Spisula solidissima. To evaluate the degree to which the results are typical, we analyze a dataset for the principal carbonate producer of Mid-Atlantic estuaries, the Eastern oyster Crassostrea virginica, obtained from Delaware Bay. These two species occupy different habitats and display different lifestyles, yet demonstrate similar challenges to survey design and similar trends with sampling density. The median of a series of simulated survey mean abundances, the central tendency obtained over a large number of surveys of the same area, always underestimated true abundance at low sample densities. More dramatic were the trends in the probability of a biased outcome. As sample density declined, the probability of a survey availability event, defined as a survey yielding indices >125% or <75% of the true population abundance, increased and that increase was disproportionately biased towards underestimates. For these cases where a single sample accessed about 0.001-0.004% of the domain, 8-15 random samples were required to reduce the probability of a survey availability event below 40%. The problem of differential bias, in which the probabilities of a biased-high and a biased-low survey index were distinctly unequal, was resolved with fewer samples than the problem of overall bias. These trends suggest that the influence of sampling density on survey design comes with a series of incremental challenges. At woefully inadequate sampling density, the probability of a biased-low survey index will substantially exceed the probability of a biased-high index. The survey time series on the average will return an estimate of the stock that underestimates true stock abundance. If sampling intensity is increased, the frequency of biased indices balances between high and low values. Incrementing sample number from this point steadily reduces the likelihood of a biased survey; however, the number of samples necessary to drive the probability of survey availability events to a preferred level of infrequency may be daunting. Moreover, certain size classes will be disproportionately susceptible to such events and the impact on size frequency will be species specific, depending on the relative dispersion of the size classes.

Variation in angler distribution and catch rates of stocked rainbow trout in a small reservoir

USGS Publications Warehouse

Harmon, Brian S.; Martin, Dustin R.; Chizinski, Christopher J.; Pope, Kevin L.

2018-01-01

We investigated the spatial and temporal relationship of catch rates and angler party location for two days following a publicly announced put-and-take stocking of rainbow trout (Oncorhynchus mykiss). Catch rates declined with time since stocking and distance from stocking. We hypothesized that opportunity for high catch rates would cause anglers to fish near the stocking location and disperse with time, however distance between angler parties and stocking was highly variable at any given time. Spatially explicit differences in catch rates can affect fishing quality. Further research could investigate the variation between angler distribution and fish distribution within a waterbody.

A pharmacy too far? Equity and spatial distribution of outcomes in the delivery of subsidized artemisinin-based combination therapies through private drug shops

PubMed Central

2010-01-01

Background Millions of individuals with malaria-like fevers purchase drugs from private retailers, but artemisinin-based combination therapies (ACTs), the only effective treatment in regions with high levels of resistance to older drugs, are rarely obtained through these outlets due to their relatively high cost. To encourage scale up of ACTs, the Affordable Medicines Facility – malaria is being launched to subsidize their price. The Government of Tanzania and the Clinton Foundation piloted this subsidized distribution model in two Tanzanian districts to examine concerns about whether the intervention will successfully reach poor, rural communities. Methods Stocking of ACTs and other antimalarial drugs in all retail shops was observed at baseline and in four subsequent surveys over 15 months. Exit interviews were conducted with antimalarial drug customers during each survey period. All shops and facilities were georeferenced, and variables related to population density and proximity to distribution hubs, roads, and other facilities were calculated. To understand the equity of impact, shops stocking ACTs and consumers buying them were compared to those that did not, according to geographic and socioeconomic variables. Patterning in ACT stocking and sales was evaluated against that of other common antimalarials to identify factors that may have impacted access. Qualitative data were used to assess motivations underlying stocking, distribution, and buying disparities. Results Results indicated that although total ACT purchases rose from negligible levels to nearly half of total antimalarial sales over the course of the pilot, considerable geographic variation in stocking and sales persisted and was related to a variety of socio-spatial factors; ACTs were stocked more often in shops located closer to district towns (p<0.01) and major roads (p<0.01) and frequented by individuals of higher socioeconomic status (p<0.01). However, other antimalarial drugs displayed similar patterning, indicating the existence of underlying disparities in access to antimalarial drugs in general in these districts. Conclusions As this subsidy model is scaled up across multiple countries, these results confirm the potential for increased ACT usage but suggest that additional efforts to increase access in remote areas will be needed for the scale-up to have equitable impact. Trial registration Current Controlled Trials ISRCTN39125414. PMID:20594372

A pharmacy too far? Equity and spatial distribution of outcomes in the delivery of subsidized artemisinin-based combination therapies through private drug shops.

PubMed

Cohen, Justin M; Sabot, Oliver; Sabot, Kate; Gordon, Megumi; Gross, Isaac; Bishop, David; Odhiambo, Moses; Ipuge, Yahya; Ward, Lorrayne; Mwita, Alex; Goodman, Catherine

2010-07-02

Millions of individuals with malaria-like fevers purchase drugs from private retailers, but artemisinin-based combination therapies (ACTs), the only effective treatment in regions with high levels of resistance to older drugs, are rarely obtained through these outlets due to their relatively high cost. To encourage scale up of ACTs, the Affordable Medicines Facility--malaria is being launched to subsidize their price. The Government of Tanzania and the Clinton Foundation piloted this subsidized distribution model in two Tanzanian districts to examine concerns about whether the intervention will successfully reach poor, rural communities. Stocking of ACTs and other antimalarial drugs in all retail shops was observed at baseline and in four subsequent surveys over 15 months. Exit interviews were conducted with antimalarial drug customers during each survey period. All shops and facilities were georeferenced, and variables related to population density and proximity to distribution hubs, roads, and other facilities were calculated. To understand the equity of impact, shops stocking ACTs and consumers buying them were compared to those that did not, according to geographic and socioeconomic variables. Patterning in ACT stocking and sales was evaluated against that of other common antimalarials to identify factors that may have impacted access. Qualitative data were used to assess motivations underlying stocking, distribution, and buying disparities. Results indicated that although total ACT purchases rose from negligible levels to nearly half of total antimalarial sales over the course of the pilot, considerable geographic variation in stocking and sales persisted and was related to a variety of socio-spatial factors; ACTs were stocked more often in shops located closer to district towns (p<0.01) and major roads (p<0.01) and frequented by individuals of higher socioeconomic status (p<0.01). However, other antimalarial drugs displayed similar patterning, indicating the existence of underlying disparities in access to antimalarial drugs in general in these districts. As this subsidy model is scaled up across multiple countries, these results confirm the potential for increased ACT usage but suggest that additional efforts to increase access in remote areas will be needed for the scale-up to have equitable impact. Current Controlled Trials ISRCTN39125414.

[Remote sensing estimation of urban forest carbon stocks based on QuickBird images].

PubMed

Xu, Li-Hua; Zhang, Jie-Cun; Huang, Bo; Wang, Huan-Huan; Yue, Wen-Ze

2014-10-01

Urban forest is one of the positive factors that increase urban carbon sequestration, which makes great contribution to the global carbon cycle. Based on the high spatial resolution imagery of QuickBird in the study area within the ring road in Yiwu, Zhejiang, the forests in the area were divided into four types, i. e., park-forest, shelter-forest, company-forest and others. With the carbon stock from sample plot as dependent variable, at the significance level of 0.01, the stepwise linear regression method was used to select independent variables from 50 factors such as band grayscale values, vegetation index, texture information and so on. Finally, the remote sensing based forest carbon stock estimation models for the four types of forest were established. The estimation accuracies for all the models were around 70%, with the total carbon reserve of each forest type in the area being estimated as 3623. 80, 5245.78, 5284.84, 5343.65 t, respectively. From the carbon density map, it was found that the carbon reserves were mainly in the range of 25-35 t · hm(-2). In the future, urban forest planners could further improve the ability of forest carbon sequestration through afforestation and interplanting of trees and low shrubs.

Refining soil organic carbon stock estimates for China’s palustrine wetlands

NASA Astrophysics Data System (ADS)

Ma, Kun; Liu, Junguo; Zhang, Ying; Parry, Lauren E.; Holden, Joseph; Ciais, Philippe

2015-12-01

Palustrine wetlands (PWs) include all bogs, fens, swamps and marshes that are non-saline and which are not lakes or rivers. They therefore form a highly important group of wetlands which hold large carbon stocks. If these wetlands are not protected properly they could become a net carbon source in the future. Compilation of spatially explicit wetland databases, national inventory data and in situ measurement of soil organic carbon (SOC) could be useful to better quantify SOC and formulate long-term strategies for mitigating global climate change. In this study, a synergistic mapping approach was used to create a hybrid map for PWs for China and to estimate their SOC content. Total SOC storage in PWs was estimated to be 4.3 ± 1.4 Pg C, with a SOC density of 31.17 (±10.55) kg C m-2 in the upper 1 m of the soil layer. This carbon stock is concentrated in Northeast China (49%) and the Qinghai-Tibet Plateau (41%). Given the large pool of carbon stored in PWs compared to other soil types, we suggest that urgent monitoring programmes on SOC should be established in regions with very few datasets, but where PWs appear to be common such as the Tibet region and Northwest China.

Greed, fear and stock market dynamics

NASA Astrophysics Data System (ADS)

Westerhoff, Frank H.

2004-11-01

We present a behavioral stock market model in which traders are driven by greed and fear. In general, the agents optimistically believe in rising markets and thus buy stocks. But if stock prices change too abruptly, they panic and sell stocks. Our model mimics some stylized facts of stock market dynamics: (1) stock prices increase over time, (2) stock markets sometimes crash, (3) stock prices show little pair correlation between successive daily changes, and (4) periods of low volatility alternate with periods of high volatility. A strong feature of the model is that stock prices completely evolve according to a deterministic low-dimensional nonlinear law of motion.

Effects of Nitrogen Fixing Pre-Crops and Fertilizers on Physical and Chemical Properties Down the Soil Profile

NASA Astrophysics Data System (ADS)

Hobley, E.; Honermeier, B.; Don, A.; Gocke, M. I.; Amelung, W.; Kogel-Knabner, I.

2016-12-01

We investigated the effects of pre-crops with and without biological nitrogen fixation capacity (fava beans, clover mulch, fodder maize) and fertilization (no fertilizer, NPK fertilizer, PK fertilizer) on soil physico-chemical properties (bulk density, electrical conductivity, soil organic carbon (SOC) concentration and stocks, N concentration and stocks) and their depth distribution (down to 1 m) at a long-term field experiment set up in 1982 in Gießen, Germany. Fertilization had significant but small impacts on the soil chemical environment, most particularly the salt content of the soil, with PK fertilization increasing electrical conductivity throughout the soil profile. Similarly, fertilization resulted in a small reduction of soil pH throughout the entire soil profile. The soil was physically and chemically affected by the type of pre-crop. Plots with fava beans and maize had lower bulk densities in the subsoil than those with clover. Pre-crop type also significantly affected the depth distribution of both N and SOC. Specifically, clover pre-cropping led to an enrichment of N at the surface compared with fava beans and maize. SOC enrichment at the surface was also observed under clover, with the effect most pronounced under PK fertilization. Combined with the bulk density effects, this shift in N distribution resulted in significantly higher N stocks under clover than under fava beans. However, the total stocks of SOC were not affected by pre-crop or fertilizer regime. Our results indicate that humans influence C and N cycling and distribution in soils through the selection of pre-crops and that the influence of crop type is greater than that of fertilization regimes. Pre-cropping with clover, which is used as a mulch, leads to N enrichment in the topsoil, reducing the need for N fertilizer for the subsequent cereal crop. In contrast, the use of fava beans as a pre-crop does not lead to N enrichment. We believe this is due to the greater rooting depth of fava beans compared with clover, resulting in lower bulk density in the subsoil and associated lower stocks. Additionally, the harvest of fava beans removes N-rich biomass from the soil, lowering N-input. Lastly, the uptake of water at depth may facilitate subsoil N uptake, so that fava bean N is utilized by the cereal crop but does not lead to its enrichment in the subsoil.

A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

NASA Astrophysics Data System (ADS)

Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

2018-05-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%-44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ± 0.004 Mg/ha). Estimated C stocks for predefined jurisdictional areas ranged from 1023 ± 39 Mg in the Nisqually National Wildlife Refuge in Washington to 507,761 ± 14,822 Mg in the Terrebonne and St. Mary Parishes in Louisiana. This modeling and data synthesis effort will allow for aboveground C stocks in tidal marshes to be included in the coastal wetland section of the U.S. National Greenhouse Gas Inventory. With the increased availability of free post-processed satellite data, we provide a tractable means of modeling tidal marsh aboveground biomass and carbon at the global extent as well.

Long-Term Trends In Loblolly Pine Productivity And Stand Characteristics In Response To Stand Density And Fertilization In The Western Gulf Region

Treesearch

M.A. Sword; J. L. Chambers; Z. Tang; T. J. Dean; J. C. Goelz

2002-01-01

Two levels each of fertilization and stand density were established to create four environments in a 7-year-old loblolly pine plantation on a N and P deficient western Gulf Coastal Plain site in Louisiana. Levels of fertilization were no fertilization and application of 120 lb N and 134 lb P/ac. Levels of stand density were the original stocking (1,210 trees/ac), and...

Effects of Beak Trimming, Stocking Density and Sex on Carcass Yield, Carcass Components, Plasma Glucose and Triglyceride Levels in Large White Turkeys.

PubMed

Sengul, Turgay; Inci, Hakan; Sengul, Ahmet Y; Sogut, Bunyamin; Kiraz, Selahattin

2015-01-01

This study was conducted to determine the effects of beak trimming, stocking density (D) and sex (S) on live weight (LW), carcass yield and its component, and plasma glucose (PG) and triglyceride levels in Large White turkeys. To accomplish this aims, totally 288 d old large white turkey chicks (144 in each sex) were used. Beaks of 77 male and female poults were trimmed when 8 d old with an electrical beak trimmer. The birds were fed by commercial turkey rasion. Experiment was designed as 2 × 2 × 2 factorial arrangement with 3 replications in each group. Beak trimming and stocking density did not affect live weight, carcass composition and its components. The higher LW and carcass weight observed in trimmed groups. As expected, male birds are heavier than female, and carcass percentage (CP) would be adverse. However, in this study, CP of male was higher in trimmed, in 0.25 m(2)/bird. (D) × sex (S) interaction had an effect on both CP and thigh weights (p<0.05). Significantly D × S was observed in LW, CP and PG. The weight of carcass and its some components were higher in male. S × D interaction had an effect on plasma glucose level (p<0.05). Triglyceride level was affected (p<0.05) by sex. Significant relationships were found between percentage of thighs (r=0.447, p<0.01) and percentage of breast (r=0.400, p<0.01). According to this study, it can be said that trimming is useful with density of 0.25 m(2)/bird in turkey fattening.

The effects of treading by two breeds of dairy cow with different live weights on soil physical properties, poaching damage and herbage production on a poorly drained clay-loam soil.

PubMed

Tuohy, P; Fenton, O; Holden, N M; Humphreys, J

2015-11-01

There is little empirical evidence to indicate that dairy cow live weight affects the extent of soil damage at the hoof-soil interface during grazing on poorly drained permanent grassland. In the present study the impact of Holstein-Friesian (HF) dairy cows with a mean (±standard deviation) live weight of 570 (±61) kg were compared with Jersey × Holstein-Friesian (JX) with a mean live weight of 499 (±52) kg each at two stocking densities: mean 2·42 ± (0·062) and 2·66 (±0·079) cows/ha. Soil physical properties (bulk density, macroporosity, gravimetric water content, air-filled porosity, penetration resistance and shear strength), poaching damage (post-grazing soil surface deformation and hoof-print depth), herbage yield and milk production were measured throughout 2011 and 2012. Soil physical properties, post-grazing soil surface deformation and herbage production were not affected by dairy cow breed or by interactions between breed and stocking density. Hoof-print depth was higher in the HF treatments (39 v. 37 mm, s.e. 0·5 mm). Loading pressure imposed at the soil surface was the same for both breeds due to a direct correlation between live weight and hoof size. Poaching damage was greater at higher stocking density. Using the lighter JX cow offered little advantage in terms of lowering the negative impact of treading on soil physical properties or reducing poaching damage and no advantage in terms of herbage or milk production compared with the heavier HF cow.

Effects of Beak Trimming, Stocking Density and Sex on Carcass Yield, Carcass Components, Plasma Glucose and Triglyceride Levels in Large White Turkeys

PubMed Central

Kiraz, Selahattin

2015-01-01

This study was conducted to determine the effects of beak trimming, stocking density (D) and sex (S) on live weight (LW), carcass yield and its component, and plasma glucose (PG) and triglyceride levels in Large White turkeys. To accomplish this aims, totally 288 d old large white turkey chicks (144 in each sex) were used. Beaks of 77 male and female poults were trimmed when 8 d old with an electrical beak trimmer. The birds were fed by commercial turkey rasion. Experiment was designed as 2 × 2 × 2 factorial arrangement with 3 replications in each group. Beak trimming and stocking density did not affect live weight, carcass composition and its components. The higher LW and carcass weight observed in trimmed groups. As expected, male birds are heavier than female, and carcass percentage (CP) would be adverse. However, in this study, CP of male was higher in trimmed, in 0.25 m2/bird. (D) × sex (S) interaction had an effect on both CP and thigh weights (p<0.05). Significantly D × S was observed in LW, CP and PG. The weight of carcass and its some components were higher in male. S × D interaction had an effect on plasma glucose level (p<0.05). Triglyceride level was affected (p<0.05) by sex. Significant relationships were found between percentage of thighs (r=0.447, p<0.01) and percentage of breast (r=0.400, p<0.01). According to this study, it can be said that trimming is useful with density of 0.25 m2/bird in turkey fattening. PMID:26877630

Returning forests analyzed with the forest identity.

PubMed

Kauppi, Pekka E; Ausubel, Jesse H; Fang, Jingyun; Mather, Alexander S; Sedjo, Roger A; Waggoner, Paul E

2006-11-14

Amid widespread reports of deforestation, some nations have nevertheless experienced transitions from deforestation to reforestation. In a causal relationship, the Forest Identity relates the carbon sequestered in forests to the changing variables of national or regional forest area, growing stock density per area, biomass per growing stock volume, and carbon concentration in the biomass. It quantifies the sources of change of a nation's forests. The Identity also logically relates the quantitative impact on forest expanse of shifting timber harvest to regions and plantations where density grows faster. Among 50 nations with extensive forests reported in the Food and Agriculture Organization's comprehensive Global Forest Resources Assessment 2005, no nation where annual per capita gross domestic product exceeded 4,600 dollars had a negative rate of growing stock change. Using the Forest Identity and national data from the Assessment report, a single synoptic chart arrays the 50 nations with coordinates of the rates of change of basic variables, reveals both clusters of nations and outliers, and suggests trends in returning forests and their attributes. The Forest Identity also could serve as a tool for setting forest goals and illuminating how national policies accelerate or retard the forest transitions that are diffusing among nations.

Linking plant functional traits and forest carbon stocks in the Congo Basin

NASA Astrophysics Data System (ADS)

Kearsley, Elizabeth; Verbeeck, Hans; Hufkens, Koen; Lewis, Simon; Huygens, Dries; Beeckman, Hans; Steppe, Kathy; Boeckx, Pascal

2013-04-01

Accurate estimates of the amount of carbon stored in tropical forests represent crucial baseline data for recent climate change mitigation policies. Such data are needed to quantify possible emissions due to deforestation and forest degradation, and to evaluate the potential of these forests to act as carbon sinks. Currently, only rough estimates of the carbon stocks for Central African tropical forests are available due to a lack of field data, and little is known about the response of these stocks to climate change. We present the first ground-based carbon stock data for the central Congo Basin in Yangambi, D. R. Congo, based on data of 20 inventory plots of 1 ha covering different forest types. We found an average aboveground carbon stock of 163 ± 19 Mg C ha-1 for intact old-growth forest, which is significantly lower than the stocks recorded in the outer regions of the Congo Basin. Commonly studied drivers for variations of carbon stocks include climatic and edaphic factors, but detailed trait-based studies are lacking. We identified a significant difference in height-diameter relations across the Congo Basin as a driver for spatial differences in carbon stocks. The study of a more detailed interaction of the environment and the available tree species pool as drivers for differences in carbon storage could have large implications. The effect of the species pool on carbon storage can be large since species differ in their ability to sequester carbon, and the collective functional characteristics of plant communities could be a major driver of carbon accumulation. The use of a trait-based approach shows high potential for identifying and quantifying carbon stocks as an ecosystem service. We test for associations between functional trait values and carbon storage across multiple regrowth and old-growth forests types in the Yangambi study area, with soil properties and climate similar for all plots. A selection of traits associated with carbon dynamics is made, including leaf traits (specific leaf area, leaf dry matter content, leaf carbon concentration, leaf nitrogen and phosphorus concentration, 13C, 15N, 18O), stem traits (wood density, vessel diameter), and vegetative traits (tree height, light tolerance), studying 990 individuals covering 111 species. To develop a more coherent understanding of ecosystem functioning, the related carbon sequestration, and the contribution of climate and soil factors in tropical forests in the Congo Basin, we present a preliminary spatial study of plant functional traits and diversity by comparing several sites across the Congo Basin.

The Tail Exponent for Stock Returns in Bursa Malaysia for 2003-2008

NASA Astrophysics Data System (ADS)

Rusli, N. H.; Gopir, G.; Usang, M. D.

2010-07-01

A developed discipline of econophysics that has been introduced is exhibiting the application of mathematical tools that are usually applied to the physical models for the study of financial models. In this study, an analysis of the time series behavior of several blue chip and penny stock companies in Main Market of Bursa Malaysia has been performed. Generally, the basic quantity being used is the relative price changes or is called the stock price returns, contains daily-sampled data from the beginning of 2003 until the end of 2008, containing 1555 trading days recorded. The aim of this paper is to investigate the tail exponent in tails of the distribution for blue chip stocks and penny stocks financial returns in six years period. By using a standard regression method, it is found that the distribution performed double scaling on the log-log plot of the cumulative probability of the normalized returns. Thus we calculate α for a small scale return as well as large scale return. Based on the result obtained, it is found that the power-law behavior for the probability density functions of the stock price absolute returns P(z)˜z-α with values lying inside and outside the Lévy stable regime with values α>2. All the results were discussed in detail.

Detecting anomalous traders using multi-slice network analysis

NASA Astrophysics Data System (ADS)

Sun, Xiao-Qian; Shen, Hua-Wei; Cheng, Xue-Qi; Zhang, Yuqing

2017-05-01

Manipulation is an important issue for both developed and emerging stock markets. Many efforts have been made to detect manipulation in stock market. However, it is still an open problem to identify the fraudulent traders, especially when they collude with each other. In this paper, we focus on the problem of identifying anomalous traders using the transaction data of 8 manipulated stocks and 42 non-manipulated stocks during a one-year period. For each stock, we construct a multi-slice trading network to characterize the daily trading behavior and the cross-day participation of each trader. Comparing the multi-slice trading network of manipulated stocks and non-manipulated stocks with their randomized version, we find that manipulated stocks exhibit high number of trader pairs that trade with each other in multiple days and high deviation from randomized network at correlation between trading frequency and trading activity. These findings are effective at distinguishing manipulated stocks from non-manipulated ones and at identifying anomalous traders.

Distinguishing manipulated stocks via trading network analysis

NASA Astrophysics Data System (ADS)

Sun, Xiao-Qian; Cheng, Xue-Qi; Shen, Hua-Wei; Wang, Zhao-Yang

2011-10-01

Manipulation is an important issue for both developed and emerging stock markets. For the study of manipulation, it is critical to analyze investor behavior in the stock market. In this paper, an analysis of the full transaction records of over a hundred stocks in a one-year period is conducted. For each stock, a trading network is constructed to characterize the relations among its investors. In trading networks, nodes represent investors and a directed link connects a stock seller to a buyer with the total trade size as the weight of the link, and the node strength is the sum of all edge weights of a node. For all these trading networks, we find that the node degree and node strength both have tails following a power-law distribution. Compared with non-manipulated stocks, manipulated stocks have a high lower bound of the power-law tail, a high average degree of the trading network and a low correlation between the price return and the seller-buyer ratio. These findings may help us to detect manipulated stocks.

Effects of adjacent land-use types on the distribution of soil organic carbon stocks in the montane area of central Taiwan.

PubMed

Chen, Chiou-Pin; Juang, Kai-Wei; Cheng, Chih-Hsin; Pai, Chuang-Wen

2016-12-01

Soil organic carbon (SOC) stocks can be altered through reforestation and cropping. We estimated the effects of land use on SOC stocks after natural deciduous forests replaced by crops and coniferous plantations by examining the vertical distribution of SOC stocks at different depth intervals in an adjacent Oolong tea (Camellia sinensis L.) plantation, Moso bamboo (Phyllostachys pubescens) forest, Japanese cedar (Cryptomeria japonica) forest, and Taiwania (Taiwania cryptomerioides) forest in central Taiwan. The main soil characteristics, soil nitrogen (N) content, and soil carbon to nitrogen (C/N) ratio were also determined. Different land uses resulted in significantly higher bulk density, lower cation exchange capacity, SOC, soil N, soil C/N ratio, and SOC stocks in croplands compared to forestlands. Due to the long-term application of chemical fertilizers, a significantly lower soil pH was found in the tea plantation. Croplands had a lower soil C/N ratio because of less C input into the soil and a higher mineralization rate of organic carbon during cultivation. Similar SOC stocks were found in Taiwania and Japanese cedar forests (148.5 and 151.8 Mg C ha -1 , respectively), while the tea plantation had comparable SOC stocks to the bamboo forest (101.8 and 100.5 Mg C ha -1 , respectively). Over 40% of SOC stocks was stored in croplands and over 56% was stored in forestland within the upper 10 cm of soil. Coniferous plantations can contribute to a higher SOC stock than croplands, and a significant difference can be found in the top 0-5 cm of soil.

The stability of portfolio investment in stock crashes

NASA Astrophysics Data System (ADS)

Li, Yun-Xian; Qian, Zhen-Wei; Li, Jiang-Cheng; Tang, Nian-Sheng; Mei, Dong-Cheng

2016-08-01

The stability of portfolio investment in stock market crashes with Markowitz portfolio is investigated by the method of theoretical and empirical simulation. From numerical simulation of the mean escape time (MET), we conclude that: (i) The increasing number (Np) of stocks in Markowitz portfolio induces a maximum in the curve of MET versus the initial position; (ii) A critical value of Np in the behavior of MET versus the long-run variance or amplitude of volatility fluctuations maximumlly enhances the stability of portfolio investment. When Np takes value below the critical value, the increasing Np enhances the stability of portfolio investment, but restrains it when Np takes value above the critical value. In addition, a good agreement of both the MET and probability density functions of returns is found between real data and theoretical results.

Determining the efficacy of microsatellite DNA-based mixed-stock analysis of Lake Michigan’s lake whitefish commercial fishery

USGS Publications Warehouse

VanDeHey, Justin A.; Sloss, Brian L.; Peeters, Paul J.; Sutton, Trent M.

2009-01-01

Management of commercially exploited fish should be conducted at the stock level. If a mixed stock fishery exists, a comprehensive mixed stock analysis is required for stock-based management. The lake whitefish Coregonus clupeaformis comprises the primary commercial fishery across the Great Lakes. Recent research resolved that six genetic stocks of lake whitefish were present in Lake Michigan, and long-term tagging data indicate that Lake Michigan's lake whitefish commercial fishery is a mixed stock fishery. The objective of this research was to determine the usefulness of microsatellite data for conducting comprehensive mixed stock analyses of the Lake Michigan lake whitefish commercial fishery. We used the individual assignment method as implemented in the program ONCOR to determine the accuracy level at which microsatellite data can reliably identify component populations or stocks. Self-assignment of lake whitefish to their population and stock of origin ranged from > 96% to 100%. Evaluation of genetic stock discreteness indicated a moderately high degree of correct assignment (average = 75%); simulations indicated supplementing baseline data by ∼ 50 to 100 individuals could increase accuracy by up to 4.5%. Simulated mixed stock commercial harvests with known stock composition showed a high degree of correct proportional assignment between observed and predicted harvest values. These data suggest that a comprehensive mixed stock analysis of Lake Michigan's lake whitefish commercial fishery is viable and would provide valuable information for improving management.

Targeted carbon conservation at national scales with high-resolution monitoring

PubMed Central

Asner, Gregory P.; Knapp, David E.; Martin, Roberta E.; Tupayachi, Raul; Anderson, Christopher B.; Mascaro, Joseph; Sinca, Felipe; Chadwick, K. Dana; Higgins, Mark; Farfan, William; Llactayo, William; Silman, Miles R.

2014-01-01

Terrestrial carbon conservation can provide critical environmental, social, and climate benefits. Yet, the geographically complex mosaic of threats to, and opportunities for, conserving carbon in landscapes remain largely unresolved at national scales. Using a new high-resolution carbon mapping approach applied to Perú, a megadiverse country undergoing rapid land use change, we found that at least 0.8 Pg of aboveground carbon stocks are at imminent risk of emission from land use activities. Map-based information on the natural controls over carbon density, as well as current ecosystem threats and protections, revealed three biogeographically explicit strategies that fully offset forthcoming land-use emissions. High-resolution carbon mapping affords targeted interventions to reduce greenhouse gas emissions in rapidly developing tropical nations. PMID:25385593

Targeted carbon conservation at national scales with high-resolution monitoring.

PubMed

Asner, Gregory P; Knapp, David E; Martin, Roberta E; Tupayachi, Raul; Anderson, Christopher B; Mascaro, Joseph; Sinca, Felipe; Chadwick, K Dana; Higgins, Mark; Farfan, William; Llactayo, William; Silman, Miles R

2014-11-25

Terrestrial carbon conservation can provide critical environmental, social, and climate benefits. Yet, the geographically complex mosaic of threats to, and opportunities for, conserving carbon in landscapes remain largely unresolved at national scales. Using a new high-resolution carbon mapping approach applied to Perú, a megadiverse country undergoing rapid land use change, we found that at least 0.8 Pg of aboveground carbon stocks are at imminent risk of emission from land use activities. Map-based information on the natural controls over carbon density, as well as current ecosystem threats and protections, revealed three biogeographically explicit strategies that fully offset forthcoming land-use emissions. High-resolution carbon mapping affords targeted interventions to reduce greenhouse gas emissions in rapidly developing tropical nations.

Population dynamics and potential of fisheries stock enhancement: practical theory for assessment and policy analysis.

PubMed

Lorenzen, Kai

2005-01-29

The population dynamics of fisheries stock enhancement, and its potential for generating benefits over and above those obtainable from optimal exploitation of wild stocks alone are poorly understood and highly controversial. I review pertinent knowledge of fish population biology, and extend the dynamic pool theory of fishing to stock enhancement by unpacking recruitment, incorporating regulation in the recruited stock, and accounting for biological differences between wild and hatchery fish. I then analyse the dynamics of stock enhancement and its potential role in fisheries management, using the candidate stock of North Sea sole as an example and considering economic as well as biological criteria. Enhancement through release of recruits or advanced juveniles is predicted to increase total yield and stock abundance, but reduce abundance of the naturally recruited stock component through compensatory responses or overfishing. Economic feasibility of enhancement is subject to strong constraints, including trade-offs between the costs of fishing and hatchery releases. Costs of hatchery fish strongly influence optimal policy, which may range from no enhancement at high cost to high levels of stocking and fishing effort at low cost. Release of genetically maladapted fish reduces the effectiveness of enhancement, and is most detrimental overall if fitness of hatchery fish is only moderately compromised. As a temporary measure for the rebuilding of depleted stocks, enhancement cannot substitute for effort limitation, and is advantageous as an auxiliary measure only if the population has been reduced to a very low proportion of its unexploited biomass. Quantitative analysis of population dynamics is central to the responsible use of stock enhancement in fisheries management, and the necessary tools are available.

A study of tail tip necrosis in young fattening bulls on slatted floors.

PubMed

Madsen, E B; Nielsen, K

1985-01-01

A questionnaire sent to 78 producers revealed that tail tip necrosis was seen only in units with fattening bulls housed on slatted floors. Out of 43 such units, 20 (46.5 per cent) reported that tail tip necrosis was a herd problem. All 43 herds were visited, owners were interviewed and housing and management data recorded. It is concluded that tail tip necrosis is a multifactorial disease. The initial lesion is caused by tramping, but the following factors are essential in the development and severity of the disease, i) slatted concrete floors, ii) close confinement, iii) hot season and iv) body weight above 200 kg. The stocking density (expressed as kg bodyweight per square meter pen) was significantly higher in problem herds (210 kg/m2) than in control herds (165 kg/m2). There was a close relationship between high environmental temperature and tail tip necroses. The majority of incidents occurred during the warm season (May through September), very few cases were seen during the colder months. The general morbidity and mortality rates were significantly higher in problem herds than in control herds. Microbiology of affected tails revealed mixed infections in most cases, with Corynebacterium pyogenes and Bacteroides melaninogenicus as the most frequently isolated organisms. Principles of treatment and prevention are discussed. There is evidence to assume that a 10-20 per cent reduction in stocking density could be an efficient prophylactic measure.

Shortleaf pine reproduction abundance and growth in pine-oak stands in the Missouri Ozarks

Treesearch

Elizabeth M. Blizzard; Doyle Henken; John M. Kabrick; Daniel C. Dey; David R. Larsen; David Gwaze

2007-01-01

We conducted an operational study to evaluate effect of site preparation treatments on pine reproduction density and the impact of overstory basal area and understory density on pine reproduction height and basal diameter in pine-oak stands in the Missouri Ozarks. Stands were harvested to or below B-level stocking, but patchiness of the oak decline lead to some plots...

Growth of western larch after thinning from above and below to several density levels: 10-year results.

Treesearch

K.W. Seidel

1980-01-01

The 10-year growth of a 55-year-old, even-aged western larch (Larix occidentalis Nutt.) stand after it was thinned from above and below to a wide range of stocking levels was measured in eastern Oregon. Basal area and volume growth increased as stand density increased for both thinning methods. Despite heavy infestations of the larch casebearer...

Growth and yield of western larch in response to several density levels and two thinning methods: 15-year results.

Treesearch

K.W. Seidel

1986-01-01

The 15-year growth response from a levels-of-growing-stock study in an even-aged western larch (Larix occidentalis Nutt.) stand, first thinned from above and below at age 55, was measured in northeastern Oregon. Basal area and volume growth increased with stand density for both thinning methods, whereas diameter growth decreased. Attacks of the...

Organic matter turnover in subsoils: current knowledge and future challenges

NASA Astrophysics Data System (ADS)

Marschner, Bernd

2014-05-01

In the past, carbon flux measurements and modelling have mostly considered the topsoil where C-concentrations, root densities and microbial activities are generally highest. However, depending on climate zone and land use, this soil compartment contains only 30-50% of the C-stocks of the first meter. If the deeper subsoil down to 3 m is also considered, the contribution of topsoil carbon stocks to total soil C-pools is only 20-40%. Another distinct property of subsoil organic matter is its high apparent 14C age. The 14C age of bulk soil organic matter below 30 cm depth generally increases continuously indicating mean residence times of several 103 to 104 years. Large pool size and high radiocarbon age suggest that subsoil OM has accumulated at very low rates over very long time periods and therefore appears to be very stable. In this review, several hypotheses for explaining why subsoil SOM is so seemingly old and inert are presented. These questions are being addressed in a recently granted German research unit consisting of 9 subprojects from all soil science disciplines using field measurements of C-fluxes, 14C analyses and conducting field and lab experiments.

Developing a Carbon Monitoring System For Pinyon-juniper Forests and Woodlands

NASA Astrophysics Data System (ADS)

Falkowski, M. J.; Hudak, A. T.; Fekety, P.; Filippelli, S.

2017-12-01

Pinyon-juniper (PJ) forests and woodlands are the third largest vegetation type in the United States. They cover over 40 million hectares across the western US, representing 40% of the total forest and woodland area in the Intermountain West. Although the density of carbon stored in these ecosystems is relatively low compared to other forest types, the vast area of short stature forests and woodlands (both nationally and globally) make them critical components of regional, national, and global carbon budgets. The overarching goal of this research is to prototype a carbon monitoring, reporting, and verification (MRV) system for characterizing total aboveground biomass stocks and flux across the PJ vegetation gradient in the western United States. We achieve this by combining in situ forest measurements and novel allometric equations with tree measurements derived from high resolution airborne imagery to map aboveground biomass across 500,000 km2 in the Western US. These high-resolution maps of aboveground biomass are then leveraged as training data to predict biomass flux through time from Landsat time-series data. The results from this research highlight the potential in mapping biomass stocks and flux in open forests and woodlands, and could be easily adopted into an MRV framework.

Behaviour of laying hens in two types of aviary systems on 25 commercial farms in Sweden.

PubMed

Odén, K; Keeling, L J; Algers, B

2002-05-01

1. Fifty-one flocks of laying hens in two high-density loose-housing systems were studied on 25 commercial farms in Sweden as part of a government test programme for evaluating new systems for laying hens. Six different hybrids were used in group sizes ranging from 250 to 5 000 birds. Stocking-densities varied from 10.2 to 19.1 birds per m2 floor area. No birds were beak trimmed. 2. The distribution of birds in the system, the frequency and location of aggressive pecks and feather pecks, the dust bathing activity and the birds' fear reaction to the keeper and to a novel object were measured. Direct behaviour observations were carried out twice per flock, at weeks 35 and 55. 3. The proportion of birds at the different locations was relatively constant across the 8-h observation period in the tiered system, but changed over time in the perch system, which may reflect a difference in access to resources between the systems. At night the top perches/tiers were preferred although when stocking-density increased, other sites were also used. 4. Aggression occurred mainly on the litter or in the nest areas. It did not differ between hybrids, but increased with age in the tiered system. Feather pecks occurred mainly on the litter. Brown hybrids feather pecked more than white ones, while white hybrids reacted more both to the keeper and to a novel object than did the brown hybrids. 5. It was concluded that access to nests was insufficient in both systems, as was litter space. Feed space was insufficient in the tiered system if food requirements increased. Design of the top perches, in the perch system, should be improved to allow birds to perch high up in the system without blocking access to feed etc. for others.

Mixed-species allometric equations and estimation of aboveground biomass and carbon stocks in restoring degraded landscape in northern Ethiopia

NASA Astrophysics Data System (ADS)

Mokria, Mulugeta; Mekuria, Wolde; Gebrekirstos, Aster; Aynekulu, Ermias; Belay, Beyene; Gashaw, Tadesse; Bräuning, Achim

2018-02-01

Accurate biomass estimation is critical to quantify the changes in biomass and carbon stocks following the restoration of degraded landscapes. However, there is lack of site-specific allometric equations for the estimation of aboveground biomass (AGB), which consequently limits our understanding of the contributions of restoration efforts in mitigating climate change. This study was conducted in northwestern Ethiopia to develop a multi-species allometric equation and investigate the spatial and temporal variation of C-stocks following the restoration of degraded landscapes. We harvested and weighed 84 trees from eleven dominant species from six grazing exclosures and adjacent communal grazing land. We observed that AGB correlates significantly with diameter at stump height D 30 (R 2 = 0.78 P < 0.01), and tree height H (R 2 = 0.41, P < 0.05). Our best model, which includes D 30 and H as predictors explained 82% of the variations in AGB. This model produced the lowest bias with narrow ranges of errors across different diameter classes. Estimated C-stock showed a significant positive correlation with stem density (R 2 = 0.80, P < 0.01) and basal area (R 2 = 0.84, P < 0.01). At the watershed level, the mean C-stock was 3.8 (±0.5) Mg C ha-1. Plot-level C-stocks varied between 0.1 and 13.7 Mg C ha-1. Estimated C-stocks in three- and seven-year-old exclosures exceeded estimated C-stock in the communal grazing land by 50%. The species that contribute most to C-stocks were Leucaena sp. (28%), Calpurnia aurea (21%), Euclea racemosa (20.9%), and Dodonaea angustifolia (15.8%). The equations developed in this study allow monitoring changes in C-stocks and C-sequestration following the implementation of restoration practices in northern Ethiopia over space and time. The estimated C-stocks can be used as a reference against which future changes in C-stocks can be compared.

Evaluating shellfish gathering ( Lucina pectinata) in a tropical mangrove system

NASA Astrophysics Data System (ADS)

Rondinelli, S. F.; Barros, F.

2010-10-01

Fish resources are important sources of income and protein to traditional inhabitants of coastal zones. In Garapuá village, the shellfish Lucina pectinata is the main resource exploited in mangroves. This study tests whether if in less explored areas (far from the village) L. pectinata individuals have higher densities and greater lengths, and if there was a decrease in cpue's over the last years. Samples were taken monthly in two habitats (mangrove channels and mangrove roots) in six mangrove areas by random squares. The results indicated that closer areas showed significantly lower densities than areas far from the village. Densities were significantly higher in mangrove roots (quizangas) than at channels. There was a significant increase in monthly L. pectinata cpue, from 18.2 dz./shellfish gatherers/day in 2001 to 19.3 in 2007, showing that this stock does not seem to be overexploited. However, (i) a long-term monitoring of Garapuá shellfish gatherers to evaluate if the stock will support an increasing pressure and (ii) several manipulative experiments to better understand ecological processes are suggested.

Interactions between striped bass and other gamefish in reservoirs

USGS Publications Warehouse

Miranda, Leandro E.; Raborn, Scott W.

2013-01-01

Competitive interactions among reservoir fishes may be pronounced because fish assemblages in these artificial environments have had little time to develop niche-partitioning strategies that alleviate negative interspecific interactions. Such interactions may at times have been intensified by introductions of predators such as striped bass Morone saxatilis, introduced to create additional fisheries and control pelagic clupeids. Possible interactions between existing fish assemblages and striped bass include predation and competition. While there is a perception among angler groups that predation by striped bass on co-existing game fish is significant, most studies have reported little or no predation on game fish my striped bass and have considered predation rare and inconsequential. Moreover, predation that occurs will likely be compensatory and fail to reduce overall game fish survival. Any indirect effect of striped bass predation by restricting prey-sized game fish to limited refuge sites remains unknown. Exploitative competition may be more common. Although infrequently, introduced striped bass have depleted prey resources shared with other piscivores, particularly when stocking rates have been high, when there is a high rate of natural reproduction, or when prey supply has plunged in response to environmental fluxes. Fluctuation in prey supply, associated with ordinary environmental variability, and associated time lages in prey supply and predator demand, preclude adjusting predator densities to exactly balance demand with supply. The frequency of low supply-demand rations varies across systems and exhibits seasonal trends. Nevertheless, chronic supply-demand imbalances are manageable where the predator assemblage is at least partially controlled through stocking, harvest regulations, or both. Because of the poor state of knowledge concerning the parameters defining balance and because uncontrollable annual fluctuations preclude exact management of alternating prey levels, we suggest adjusting stocking to manage demand to that it equals the median historical prey supply. Simulating the removal of striped bass and predicting the aftermath may be the most cost-efficient way to provide decision support for stakeholders involved in determining if a striped bass stocking program is beneficial to most users.

Bathymetric patterns in standing stock and diversity of deep-sea nematodes at the long-term ecological research observatory HAUSGARTEN (Fram Strait)

NASA Astrophysics Data System (ADS)

Grzelak, Katarzyna; Kotwicki, Lech; Hasemann, Christiane; Soltwedel, Thomas

2017-08-01

Bathymetric patterns in standing stocks and diversity are a major topic of investigation in deep-sea biology. From the literature, responses of metazoan meiofauna and nematodes to bathymetric gradients are well studied, with a general decrease in biomass and abundance with increasing water depth, while bathymetric diversity gradients often, although it is not a rule, show a unimodal pattern. Spatial distribution patterns of nematode communities along bathymetric gradients are coupled with surface-water processes and interacting physical and biological factors within the benthic system. We studied the nematode communities at the Long-Term Ecological Research (LTER) observatory HAUSGARTEN, located in the Fram Strait at the Marginal Ice Zone, with respect to their standing stocks as well as structural and functional diversity. We evaluated whether nematode density, biomass and diversity indices, such as H0, Hinf, EG(50), Θ- 1, are linked with environmental conditions along a bathymetric transect spanning from 1200 m to 5500 m water depth. Nematode abundance, biomass and diversity, as well as food availability from phytodetritus sedimentation (indicated by chloroplastic pigments in the sediments), were higher at the stations located at upper bathyal depths (1200-2000 m) and tended to decrease with increasing water depth. A faunal shift was found below 3500 m water depth, where genus composition and trophic structure changed significantly and structural diversity indices markedly decreased. A strong dominance of very few genera and its high turnover particularly at the abyssal stations (4000-5500 m) suggests that environmental conditions were rather unfavorable for most genera. Despite the high concentrations of sediment-bound chloroplastic pigments and elevated standing stocks found at the deepest station (5500 m), nematode genus diversity remained the lowest compared to all other stations. This study provides a further insight into the knowledge of deep-sea nematodes, their diversity patterns and a deeper understanding of the environmental factors shaping nematodes communities at bathyal and abyssal depths.

To stock or not to stock? Assessing restoration potential of a remnant American shad spawning run with hatchery supplementation

USGS Publications Warehouse

Bailey, Michael M.; Zydlewski, Joseph D.

2013-01-01

Hatchery supplementation has been widely used as a restoration technique for American Shad Alosa sapidissima on the East Coast of the USA, but results have been equivocal. In the Penobscot River, Maine, dam removals and other improvements to fish passage will likely reestablish access to the majority of this species’ historic spawning habitat. Additional efforts being considered include the stocking of larval American Shad. The decision about whether to stock a river system undergoing restoration should be made after evaluating the probability of natural recolonization and examining the costs and benefits of potentially accelerating recovery using a stocking program. However, appropriate evaluation can be confounded by a dearth of information about the starting population size and age structure of the remnant American Shad spawning run in the river. We used the Penobscot River as a case study to assess the theoretical sensitivity of recovery time to either scenario (stocking or not) by building a deterministic model of an American Shad population. This model is based on the best available estimates of size at age, fecundity, rate of iteroparity, and recruitment. Density dependence was imposed, such that the population reached a plateau at an arbitrary recovery goal of 633,000 spawning adults. Stocking had a strong accelerating effect on the time to modeled recovery (as measured by the time to reach 50% of the recovery goal) in the base model, but stocking had diminishing effects with larger population sizes. There is a diminishing return to stocking when the starting population is modestly increased. With a low starting population (a spawning run of 1,000), supplementation with 12 million larvae annually accelerated modeled recovery by 12 years. Only a 2-year acceleration was observed if the starting population was 15,000. Such a heuristic model may aid managers in assessing the costs and benefits of stocking by incorporating a structured decision framework.

Predator-Prey Interactions are Context Dependent in a Grassland Plant-Grasshopper-Wolf Spider Food Chain.

PubMed

Laws, Angela N; Joern, Anthony

2015-06-01

Species interactions are often context dependent, where outcomes vary in response to one or more environmental factors. It remains unclear how abiotic conditions like temperature combine with biotic factors such as consumer density or food quality to affect resource availability or influence species interactions. Using the large grasshopper Melanoplus bivittatus (Say) and a common wolf spider [Rabidosa rabida (Walkenaer)], we conducted manipulative field experiments in tallgrass prairie to examine how spider-grasshopper interactions respond to manipulations of temperature, grasshopper density, and food quality. Grasshopper survival was density dependent, as were the effects of spider presence and food quality in context-dependent ways. In high grasshopper density treatments, predation resulted in increased grasshopper survival, likely as a result of reduced intraspecific competition in the presence of spiders. Spiders had no effect on grasshopper survival when grasshoppers were stocked at low densities. Effects of the experimental treatments were often interdependent so that effects were only observed when examined together with other treatments. The occurrence of trophic cascades was context dependent, where the effects of food quality and spider presence varied with temperature under high-density treatments. Temperature weakly affected the impact of spider presence on M. bivittatus survivorship when all treatments were considered simultaneously, but different context-dependent responses to spider presence and food quality were observed among the three temperature treatments under high-density conditions. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how key biotic and abiotic factors combine to influence species interactions. © 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.

Current stand characteristics of Louisiana timberland harvested between 1975 and 1991

Treesearch

James F. Rosson

1994-01-01

Commercially harvested timberland was analyzed by past and current forest types, stocking, tree density, and volume. Monitoring sample plots by year of harvest gives indications of rates and degree of recovery from harvesting disturbance.

Underestimation of boreal soil carbon stocks by mathematical soil carbon models linked to soil nutrient status

NASA Astrophysics Data System (ADS)

Ťupek, Boris; Ortiz, Carina A.; Hashimoto, Shoji; Stendahl, Johan; Dahlgren, Jonas; Karltun, Erik; Lehtonen, Aleksi

2016-08-01

Inaccurate estimate of the largest terrestrial carbon pool, soil organic carbon (SOC) stock, is the major source of uncertainty in simulating feedback of climate warming on ecosystem-atmosphere carbon dioxide exchange by process-based ecosystem and soil carbon models. Although the models need to simplify complex environmental processes of soil carbon sequestration, in a large mosaic of environments a missing key driver could lead to a modeling bias in predictions of SOC stock change.We aimed to evaluate SOC stock estimates of process-based models (Yasso07, Q, and CENTURY soil sub-model v4) against a massive Swedish forest soil inventory data set (3230 samples) organized by a recursive partitioning method into distinct soil groups with underlying SOC stock development linked to physicochemical conditions.For two-thirds of measurements all models predicted accurate SOC stock levels regardless of the detail of input data, e.g., whether they ignored or included soil properties. However, in fertile sites with high N deposition, high cation exchange capacity, or moderately increased soil water content, Yasso07 and Q models underestimated SOC stocks. In comparison to Yasso07 and Q, accounting for the site-specific soil characteristics (e. g. clay content and topsoil mineral N) by CENTURY improved SOC stock estimates for sites with high clay content, but not for sites with high N deposition.Our analysis suggested that the soils with poorly predicted SOC stocks, as characterized by the high nutrient status and well-sorted parent material, indeed have had other predominant drivers of SOC stabilization lacking in the models, presumably the mycorrhizal organic uptake and organo-mineral stabilization processes. Our results imply that the role of soil nutrient status as regulator of organic matter mineralization has to be re-evaluated, since correct SOC stocks are decisive for predicting future SOC change and soil CO2 efflux.

Traditional cattle vs. introduced deer management in Chaco Serrano woodlands (Argentina): Analysis of environmental sustainability at increasing densities.

PubMed

Charro, José Luis; López-Sánchez, Aida; Perea, Ramón

2018-01-15

Wild ungulate populations have increased and expanded considerably in many regions, including austral woodlands and forests where deer (Cervus elaphus) have been introduced as an alternative management to traditional cattle grazing. In this study, we compared traditional cattle with introduced deer management at increasing deer densities in the "Chaco Serrano" woodlands of Argentina to assess their ecological sustainability. We used three ecological indicators (abundance of tree regeneration, woody plant diversity and browsing damage) as proxies for environmental sustainability in woody systems. Our results indicate that traditional cattle management, at stocking rates of ∼10 ind km -2 , was the most ecologically sustainable management since it allowed greater tree regeneration abundance, higher richness of woody species and lower browsing damage. Importantly, cattle management and deer management at low densities (10 ind km -2 ) showed no significant differences in species richness and abundance of seedlings, although deer caused greater browsing damage on saplings and juveniles. However, management regimes involving high deer densities (∼35 deer km 2 ) was highly unsustainable in comparison to low (∼10 deer km -2 ) and medium (∼20 deer km -2 ) densities, with 40% probability of unsustainable browsing as opposed to less than 5% probability at low and medium densities. In addition, high deer densities caused a strong reduction in tree regeneration, with a 19-30% reduction in the abundance of seedlings and young trees when compared to low deer densities. These results showed that the effect of increasing deer densities on woody plant conservation was not linear, with high deer densities causing a disproportional deleterious effect on tree regeneration and sustainable browsing. Our results suggest that traditional management at low densities or the use of introduced ungulates (deer breeding areas) at low-medium densities (<20 deer km -2 ) are compatible with woody vegetation conservation. However, further research is needed on plant palatability, animal habitat use (spatial heterogeneity) and species turnover and extinction (comparison to areas of low-null historical browsing) to better estimate environmental sustainability of Neotropical ungulate-dominated woodlands. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective fishing induces density-dependent growth.

PubMed

Svedäng, Henrik; Hornborg, Sara

2014-06-12

Over the last decades, views on fisheries management have oscillated between alarm and trust in management progress. The predominant policy for remedying the world fishing crisis aims at maximum sustainable yield (MSY) by adjusting gear selectivity and fishing effort. Here we report a case study on how striving for higher yields from the Eastern Baltic cod stock by increasing selectivity has become exceedingly detrimental for its productivity. Although there is a successive increase in numbers of undersized fish, growth potential is severely reduced, and fishing mortality in fishable size has increased. Once density-dependent growth is introduced, the process is self-enforcing as long as the recruitment remains stable. Our findings suggest that policies focusing on maximum yield while targeting greater sizes are risky and should instead prioritize catch rates over yield. Disregarding the underlying population structure may jeopardize stock productivity, with dire consequences for the fishing industry and ecosystem structure and function.

Changes in SOC stocks and fractions after natural afforestation of alpine grasslands

NASA Astrophysics Data System (ADS)

Guidi, Claudia; Rodeghiero, Mirco; Vesterdal, Lars; Gianelle, Damiano

2013-04-01

Land use changes are considered one of the major driving forces of global carbon fluxes and can induce significant alterations of soil organic carbon stocks. In the European Alps, the dominant form of land use change is represented by the abandonment of marginal mountain grasslands and their invasion by tree species, i.e. a transition from grassland to forest. While an increase in live and dead aboveground biomass is commonly reported, the impact on soil organic carbon (SOC) is still unclear. The main objective of the current study was to quantify the effect of abandonment and forest regrowth of mountain grassland on SOC, considering both SOC stocks and its physically separated fractions. The study area is located in a pre-alpine area of the Trentino region (Italy), with an elevation of about 1150 m. We compared four land uses representing a transition from grassland to forest: I) managed grassland; II) grassland abandoned 10 years ago; III) natural afforested grassland abandoned after 1973; IV) reference forest, already present in 1861. The afforested area and the reference forest are both dominated by Norway spruce (Picea abies) and beech (Fagus sylvatica). For each land use intensity three sampling areas were selected. In each area we collected eight soil cores to a depth of 30 cm, dividing the soil core in 4 depth increments. To assess changes in SOC stocks, we measured bulk density, stoniness, root biomass and organic carbon content. Mineral SOC stocks were calculated using both an equivalent depth and an equivalent mass approach. Changes in SOC fractions were assessed using aggregate size fractionation (Cambardella and Elliott, 1993) and size-density fractionation procedures. Preliminary results show higher soil C concentrations in forest sites compared to grassland. This can be attributed to higher C inputs and lower mineralization rates due to a higher degree of soil aggregation and protection of soil organic matter, but also to the higher stoniness registered in forest sites which can lead to a concentration of C inputs in a smaller volume of soil. If C stocks are computed using an equivalent soil depth approach, mineral SOC stocks are lower in forest land uses compared to grassland while no significant difference emerges if an equivalent soil mass approach is used. The aggregate size fractionation highlighted an increase in C stored in large macroaggregates following afforestation and a decrease in silt and clay size fraction (<53 μm). The strongest change shown through the size-density fractionation procedure is a three-fold increase in C stored in free organic matter (POM) from grassland to forest. Intriguingly, we found a decreasing trend in the microaggregate (53-250 μm) fraction as well as for the mineral-associated heavy fraction following afforestation, suggesting a decrease in the more stable SOC fraction, while the labile fractions increased.

Repeat surveys of spawning cisco (Coregonus artedi) in western Lake Superior: timing, distribution and composition of spawning stocks

USGS Publications Warehouse

Yule, Daniel L.; Schreiner, Donald R.; Addison, Peter A.; Seider, Michael J.; Evrard, Lori M.; Geving, Steven A.; Quinlan, Henry R.

2012-01-01

Acoustic (AC) and midwater trawl (MT) surveys of spawning cisco (Coregonus artedi) in Lake Superior have been combined with commercial yield to estimate exploitation. To time surveys properly, it is important to understand when adults typically arrive at spawning grounds and how numbers change as the spawning season progresses. We conducted repeat autumn surveys during nighttime hours at coastal sites where commercial roe fisheries occur. Spawner densities increased significantly from October to mid-November, but differences measured at sites sampled from mid- to late-November were comparatively small. Spawners occupied the upper 20–30 m of the water column during mid-November before utilizing a wider range of depths by late-November. We compared repeat AC densities to temporal trends of catch-per-unit-effort (CPUE) in suspended commercial gillnets and found good agreement within sites. Because different gillnet mesh sizes were used in each roe fishery. CPUE and AC density were poorly correlated among sites. We recommend that future surveys be conducted between mid- and late-November, and that MT gear be used to measure cisco densities in the uppermost 10 m of the water column where AC estimates may be conservative. Given the short temporal window for assessing spawner density, we believe both AC-MT and gillnet surveys will be needed to ensure that harvest of different stocks is kept at a sustainable level.

Temperate forest fragments maintain aboveground carbon stocks out to the forest edge despite changes in community composition.

PubMed

Ziter, Carly; Bennett, Elena M; Gonzalez, Andrew

2014-11-01

Edge effects are among the primary mechanisms by which forest fragmentation can influence the link between biodiversity and ecosystem processes, but relatively few studies have quantified these mechanisms in temperate regions. Carbon storage is an important ecosystem function altered by edge effects, with implications for climate change mitigation. Two opposing hypotheses suggest that aboveground carbon (AGC) stocks at the forest edge will (a) decrease due to increased tree mortality and compositional shifts towards smaller, lower wood density species (e.g., as seen in tropical systems) or, less often, (b) increase due to light/temperature-induced increases in diversity and productivity. We used field-based measurements, allometry, and mixed models to investigate the effects of proximity to the forest edge on AGC stocks, species richness, and community composition in 24 forest fragments in southern Quebec. We also asked whether fragment size or connectivity with surrounding forests altered these edge effects. AGC stocks remained constant across a 100 m edge-to-interior gradient in all fragment types, despite changes in tree community composition and stem density consistent with expectations of forest edge effects. We attribute this constancy primarily to compensatory effects of small trees at the forest edge; however, it is due in some cases to the retention of large trees at forest edges, likely a result of forest management. Our results suggest important differences between temperate and tropical fragments with respect to mechanisms linking biodiversity and AGC dynamics. Small temperate forest fragments may be valuable in conservation efforts based on maintaining biodiversity and multiple ecosystem services.

Eelgrass Blue Carbon-Quantification of Carbon Stocks and Sequestration Rates in Zostera Marina Beds in the Salish Sea

NASA Astrophysics Data System (ADS)

Lutz, M. D.; Rybczyk, J.; Poppe, K.; Johnson, C.; Kaminsky, M.; Lanphear, M.

2017-12-01

Seagrass meadows provide more than habitat, biodiversity support, wave abatement, and water quality improvement; they help mitigate climate change by taking up and storing (sequestering) carbon (C), reportedly at rates only surpassed worldwide by salt marsh and mangrove ecosystems. Now that their climate mitigation capacity has earned seagrass ecosystems a place in the Verified Carbon Standard voluntary greenhouse gas program, accurate ecosystem carbon accounting is essential. Though seagrasses vary in carbon storage and accumulation greatly across species and geography, the bulk of data included in calculating global averages involves tropical and subtropical seagrasses. We know little regarding carbon stocks nor sequestration rates for eelgrass (Zostera marina) meadows in the Pacific Northwest. The intent of our study was to quantify carbon stocks and sequestration rates in the central Salish Sea of Washington State. We gathered sediment cores over three bays, as close to 1 m in depth as possible, both on foot and while scuba diving. We measured bulk density, carbon concentration, carbon stock, grain size, and carbon accumulation rate with depth. Results from our study show lower estimated Corg concentration (mean = 0.39% C, SE=0.01, range=0.11-1.75, SE=0.01), Corg stock (mean=24.46 Mg ha-1, SE=0.00, range=16.31-49.99.70), and C sequestration rates (mean=33.96 g m-2yr-1, range=11.4-49.5) than those reported in published studies from most other locations. Zostera marina is highly productive, yet does not seem to have the capacity to store C in its sediments like seagrasses in warmer climes. These data have implications in carbon market trading, when determining appropriate seagrass restoration site dimensions to offset emissions from transportation, industry, and seagrass habitat disturbance. Awareness of lower rates could prevent underestimating the area appropriate for mitigation or restoration.

Modeling Soil Organic Carbon Variation Along Climatic and Topographic Trajectories in the Central Andes

NASA Astrophysics Data System (ADS)

Gavilan, C.; Grunwald, S.; Quiroz, R.; Zhu, L.

2015-12-01

The Andes represent the largest and highest mountain range in the tropics. Geological and climatic differentiation favored landscape and soil diversity, resulting in ecosystems adapted to very different climatic patterns. Although several studies support the fact that the Andes are a vast sink of soil organic carbon (SOC) only few have quantified this variable in situ. Estimating the spatial distribution of SOC stocks in data-poor and/or poorly accessible areas, like the Andean region, is challenging due to the lack of recent soil data at high spatial resolution and the wide range of coexistent ecosystems. Thus, the sampling strategy is vital in order to ensure the whole range of environmental covariates (EC) controlling SOC dynamics is represented. This approach allows grasping the variability of the area, which leads to more efficient statistical estimates and improves the modeling process. The objectives of this study were to i) characterize and model the spatial distribution of SOC stocks in the Central Andean region using soil-landscape modeling techniques, and to ii) validate and evaluate the model for predicting SOC content in the area. For that purpose, three representative study areas were identified and a suite of variables including elevation, mean annual temperature, annual precipitation and Normalized Difference Vegetation Index (NDVI), among others, was selected as EC. A stratified random sampling (namely conditioned Latin Hypercube) was implemented and a total of 400 sampling locations were identified. At all sites, four composite topsoil samples (0-30 cm) were collected within a 2 m radius. SOC content was measured using dry combustion and SOC stocks were estimated using bulk density measurements. Regression Kriging was used to map the spatial variation of SOC stocks. The accuracy, fit and bias of SOC models was assessed using a rigorous validation assessment. This study produced the first comprehensive, geospatial SOC stock assessment in this undersampled region that serves as a baseline reference to assess potential impacts of climate and land use change.

The fishery for Iceland scallop (Chlamys islandica) in the Northeast Atlantic.

PubMed

Garcia, Elena Guijarro

2006-01-01

This review focuses on the history and management of the Iceland scallop fishery in Iceland, Greenland and Norway (including the Svalbard archipelago and the islands of Bjørnøya and Jan Mayen), with information on research into each stock. The start of the fishery in all these regions followed the discovery of virgin scallop beds made up of old, large specimens in very high densities. Despite the apparent similarity of original conditions, the fishery has followed very different trends in each region, with drastic declines in Iceland, Svalbard and Jan Mayen. The general biology of the Iceland scallop is summarised and compared with the biology of other North Atlantic species of pectinids. The Icelandic fishery dates from 1969. There was a steady decrease in catch from 1985, when >16,000 tonnes were caught. By 2004 the stock had declined to 35% of its average size during the period 1993-2000 and a zero quota was advised. This decline is thought to have resulted from overexploitation, combined with a protozoan infestation and increasing sea bottom temperature. Scallop dredging commenced in west Greenland in 1983. The stock is not very large, but fishing was driven by social factors. Catches ranged from 400 to 1,900 tonnes during the period 1988-1992 and from 1,200 to 2,600 tonnes since 1995. There are indications that each scallop bed is extensively dredged before the fleet moves on to new areas, but nevertheless catches have been rather stable over the past decade. The scallop stocks in Svalbard, Bjørnøya and Jan Mayen were depleted in three fishing seasons between 1985-1987, when up to 45,000 tonnes of scallops were dredged in a single season. Following a survey carried out in 1991, Bjørnøya was open to the fishery with a maximum quota of 2,000 tonnes, but the stock off Svalbard was found to be not large enough to sustain a fishery.

Access to Barrier Perches Improves Behavior Repertoire in Broilers

PubMed Central

Ventura, Beth A.; Siewerdt, Frank; Estevez, Inma

2012-01-01

Restriction of behavioral opportunities and uneven use of space are considerable welfare concerns in modern broiler production, particularly when birds are kept at high densities. We hypothesized that increased environmental complexity by provision of barrier perches would help address these issues by encouraging perching and enhancing use of the pen space across a range of stocking densities. 2,088 day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over four replications: simple barrier, complex barrier, or control (no barrier) and low (8 birds/m2), moderate (13 birds/m2), or high (18 birds/m2) density. Data were collected on focal birds via instantaneous scan sampling from 2 to 6 weeks of age. Mean estimates per pen for percent of observations seen performing each behavior, as well as percent of observations in the pen periphery vs. center, were quantified and submitted to an analysis of variance with week as the repeated measure. Barrier perches, density and age affected the behavioral time budget of broilers. Both simple and complex barrier perches effectively stimulated high perching rates. Aggression and disturbances were lower in both barrier treatments compared to controls (P<0.05). Increasing density to 18 birds/m2 compared to the lower densities suppressed activity levels, with lower foraging (P<0.005), decreased perching (P<0.0001) and increased sitting (P = 0.001) earlier in the rearing period. Disturbances also increased at higher densities (P<0.05). Use of the central pen area was higher in simple barrier pens compared to controls (P<0.001), while increasing density above 8 birds/m2 suppressed use of the central space (P<0.05). This work confirms some negative effects of increasing density and suggests that barrier perches have the potential to improve broiler welfare by encouraging activity (notably by providing accessible opportunities to perch), decreasing aggression and disturbances, and promoting more even distribution of birds throughout the pen space. PMID:22299026

Predicting the Potential for Natural Recovery of Atlantic Salmon (Salmo salar L.) Populations following the Introduction of Gyrodactylus salaris Malmberg, 1957 (Monogenea).

PubMed

Denholm, Scott J; Hoyle, Andrew S; Shinn, Andrew P; Paladini, Giuseppe; Taylor, Nick G H; Norman, Rachel A

2016-01-01

Gyrodactylus salaris (Monogenea, Platyhelminthes) is a notifiable freshwater pathogen responsible for causing catastrophic damage to wild Atlantic salmon stocks, most notably in Norway. In some strains of Baltic salmon (e.g., from the river Neva) however, the impact is greatly reduced due to some form of innate resistance that regulates parasite numbers, resulting in fewer host mortalities. Gyrodactylus salaris is known from 17 European states; its status in a further 35 states remains unknown; the UK, the Republic of Ireland and certain watersheds in Finland are free of the parasite. Thus, the parasite poses a serious threat if it emerges in Atlantic salmon rearing regions throughout Europe. At present, infections are generally controlled via extreme measures such as the treatment of entire river catchments with the biocide rotenone, in order to remove all hosts, before restocking with the original genetic stock. The use of rotenone in this way in EU countries is unlikely as it would be in contravention of the Water Framework Directive. Not only are such treatments economically and environmentally costly, they also eradicate the potential for any host/parasite evolutionary process to occur. Based on previous studies, UK salmon stocks have been shown to be highly susceptible to infection, analogous to Norwegian stocks. The present study investigates the impact of a G. salaris outbreak within a naïve salmon population in order to determine long-term consequences of infection and the likelihood of coexistence. Simulation of the salmon/ G. salaris system was carried out via a deterministic mathematical modelling approach to examine the dynamics of host-pathogen interactions. Results indicated that in order for highly susceptible Atlantic strains to evolve a resistance, both a moderate-strong deceleratingly costly trade-off on birth rate and a lower overall cost of the immune response are required. The present study provides insights into the potential long term impact of G. salaris if introduced into G. salaris-free territories and suggests that in the absence of external controls salmon populations are likely to recover to high densities nearing 90% of that observed pre-infection.

[Variation of forest vegetation carbon storage and carbon sequestration rate in Liaoning Province, Northeast China].

PubMed

Zhen, Wei; Huang, Mei; Zhai, Yin-Li; Chen, Ke; Gong, Ya-Zhen

2014-05-01

The forest vegetation carbon stock and carbon sequestration rate in Liaoning Province, Northeast China, were predicted by using Canadian carbon balance model (CBM-CFS3) combining with the forest resource data. The future spatio-temporal distribution and trends of vegetation carbon storage, carbon density and carbon sequestration rate were projected, based on the two scenarios, i. e. with or without afforestation. The result suggested that the total forest vegetation carbon storage and carbon density in Liaoning Province in 2005 were 133.94 Tg and 25.08 t x hm(-2), respectively. The vegetation carbon storage in Quercus was the biggest, while in Robinia pseudoacacia was the least. Both Larix olgensis and broad-leaved forests had higher vegetation carbon densities than others, and the vegetation carbon densities of Pinus tabuliformis, Quercus and Robinia pseudoacacia were close to each other. The spatial distribution of forest vegetation carbon density in Liaoning Province showed a decrease trend from east to west. In the eastern forest area, the future increase of vegetation carbon density would be smaller than those in the northern forest area, because most of the forests in the former part were matured or over matured, while most of the forests in the later part were young. Under the scenario of no afforestation, the future increment of total forest vegetation carbon stock in Liaoning Province would increase gradually, and the total carbon sequestration rate would decrease, while they would both increase significantly under the afforestation scenario. Therefore, afforestation plays an important role in increasing vegetation carbon storage, carbon density and carbon sequestration rate.

Identifying Key Drivers of Return Reversal with Dynamical Bayesian Factor Graph.

PubMed

Zhao, Shuai; Tong, Yunhai; Wang, Zitian; Tan, Shaohua

2016-01-01

In the stock market, return reversal occurs when investors sell overbought stocks and buy oversold stocks, reversing the stocks' price trends. In this paper, we develop a new method to identify key drivers of return reversal by incorporating a comprehensive set of factors derived from different economic theories into one unified dynamical Bayesian factor graph. We then use the model to depict factor relationships and their dynamics, from which we make some interesting discoveries about the mechanism behind return reversals. Through extensive experiments on the US stock market, we conclude that among the various factors, the liquidity factors consistently emerge as key drivers of return reversal, which is in support of the theory of liquidity effect. Specifically, we find that stocks with high turnover rates or high Amihud illiquidity measures have a greater probability of experiencing return reversals. Apart from the consistent drivers, we find other drivers of return reversal that generally change from year to year, and they serve as important characteristics for evaluating the trends of stock returns. Besides, we also identify some seldom discussed yet enlightening inter-factor relationships, one of which shows that stocks in Finance and Insurance industry are more likely to have high Amihud illiquidity measures in comparison with those in other industries. These conclusions are robust for return reversals under different thresholds.

Levy Matrices and Financial Covariances

NASA Astrophysics Data System (ADS)

Burda, Zdzislaw; Jurkiewicz, Jerzy; Nowak, Maciej A.; Papp, Gabor; Zahed, Ismail

2003-10-01

In a given market, financial covariances capture the intra-stock correlations and can be used to address statistically the bulk nature of the market as a complex system. We provide a statistical analysis of three SP500 covariances with evidence for raw tail distributions. We study the stability of these tails against reshuffling for the SP500 data and show that the covariance with the strongest tails is robust, with a spectral density in remarkable agreement with random Lévy matrix theory. We study the inverse participation ratio for the three covariances. The strong localization observed at both ends of the spectral density is analogous to the localization exhibited in the random Lévy matrix ensemble. We discuss two competitive mechanisms responsible for the occurrence of an extensive and delocalized eigenvalue at the edge of the spectrum: (a) the Lévy character of the entries of the correlation matrix and (b) a sort of off-diagonal order induced by underlying inter-stock correlations. (b) can be destroyed by reshuffling, while (a) cannot. We show that the stocks with the largest scattering are the least susceptible to correlations, and likely candidates for the localized states. We introduce a simple model for price fluctuations which captures behavior of the SP500 covariances. It may be of importance for assets diversification.

Analysis of Terrestrial Carbon Stocks in a Small Catchment of Northeastern Siberia

NASA Astrophysics Data System (ADS)

Heard, K.; Natali, S.; Bunn, A. G.; Loranty, M. M.; Kholodov, A. L.; Schade, J. D.; Berner, L. T.; Spektor, V.; Zimov, N.; Alexander, H. D.

2015-12-01

As arctic terrestrial ecosystems comprise about one-third of the global terrestrial ecosystem carbon total, understanding arctic carbon cycling and the feedback of terrestrial carbon pools to accelerated warming is an issue of global concern. For this research, we examined above- and belowground carbon stocks in a larch-dominated catchment underlain by yedoma and located within the Kolyma River watershed in northeastern Siberia. We quantified carbon stocks in vegetation, active layer, and permafrost, and we assessed the correlation between plant and active layer carbon pools and four environmental correlates — slope, solar insolation, canopy density, and leaf area index ­— at 20 sites. Carbon in the active layer was approximately four times greater than aboveground carbon pools (972 g C m-2), and belowground carbon to 1 m depth was approximately 18 times greater than aboveground carbon pools. Canopy density and slope had a robust positive association with aboveground carbon pools, and soil moisture was positively related to %C in organic, thawed mineral and permafrost soil. Thaw depth was negatively correlated with moss cover and larch biomass, highlighting the importance of vegetation and surface characteristics on permafrost carbon vulnerability. These data suggest that landscape and ecosystem characteristics affect carbon accumulation and storage, but they also play an important role in stabilizing permafrost carbon pools.

A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

USGS Publications Warehouse

Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

2018-01-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%–44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ± 0.004 Mg/ha). Estimated C stocks for predefined jurisdictional areas ranged from 1023 ± 39 Mg in the Nisqually National Wildlife Refuge in Washington to 507,761 ± 14,822 Mg in the Terrebonne and St. Mary Parishes in Louisiana. This modeling and data synthesis effort will allow for aboveground C stocks in tidal marshes to be included in the coastal wetland section of the U.S. National Greenhouse Gas Inventory. With the increased availability of free post-processed satellite data, we provide a tractable means of modeling tidal marsh aboveground biomass and carbon at the global extent as well.

Selecting Reliable and Robust Freshwater Macroalgae for Biomass Applications

PubMed Central

Lawton, Rebecca J.; de Nys, Rocky; Paul, Nicholas A.

2013-01-01

Intensive cultivation of freshwater macroalgae is likely to increase with the development of an algal biofuels industry and algal bioremediation. However, target freshwater macroalgae species suitable for large-scale intensive cultivation have not yet been identified. Therefore, as a first step to identifying target species, we compared the productivity, growth and biochemical composition of three species representative of key freshwater macroalgae genera across a range of cultivation conditions. We then selected a primary target species and assessed its competitive ability against other species over a range of stocking densities. Oedogonium had the highest productivity (8.0 g ash free dry weight m−2 day−1), lowest ash content (3–8%), lowest water content (fresh weigh: dry weight ratio of 3.4), highest carbon content (45%) and highest bioenergy potential (higher heating value 20 MJ/kg) compared to Cladophora and Spirogyra. The higher productivity of Oedogonium relative to Cladophora and Spirogyra was consistent when algae were cultured with and without the addition of CO2 across three aeration treatments. Therefore, Oedogonium was selected as our primary target species. The competitive ability of Oedogonium was assessed by growing it in bi-cultures and polycultures with Cladophora and Spirogyra over a range of stocking densities. Cultures were initially stocked with equal proportions of each species, but after three weeks of growth the proportion of Oedogonium had increased to at least 96% (±7 S.E.) in Oedogonium-Spirogyra bi-cultures, 86% (±16 S.E.) in Oedogonium-Cladophora bi-cultures and 82% (±18 S.E.) in polycultures. The high productivity, bioenergy potential and competitive dominance of Oedogonium make this species an ideal freshwater macroalgal target for large-scale production and a valuable biomass source for bioenergy applications. These results demonstrate that freshwater macroalgae are thus far an under-utilised feedstock with much potential for biomass applications. PMID:23717561

Selecting reliable and robust freshwater macroalgae for biomass applications.

PubMed

Lawton, Rebecca J; de Nys, Rocky; Paul, Nicholas A

2013-01-01

Intensive cultivation of freshwater macroalgae is likely to increase with the development of an algal biofuels industry and algal bioremediation. However, target freshwater macroalgae species suitable for large-scale intensive cultivation have not yet been identified. Therefore, as a first step to identifying target species, we compared the productivity, growth and biochemical composition of three species representative of key freshwater macroalgae genera across a range of cultivation conditions. We then selected a primary target species and assessed its competitive ability against other species over a range of stocking densities. Oedogonium had the highest productivity (8.0 g ash free dry weight m⁻² day⁻¹), lowest ash content (3-8%), lowest water content (fresh weigh: dry weight ratio of 3.4), highest carbon content (45%) and highest bioenergy potential (higher heating value 20 MJ/kg) compared to Cladophora and Spirogyra. The higher productivity of Oedogonium relative to Cladophora and Spirogyra was consistent when algae were cultured with and without the addition of CO₂ across three aeration treatments. Therefore, Oedogonium was selected as our primary target species. The competitive ability of Oedogonium was assessed by growing it in bi-cultures and polycultures with Cladophora and Spirogyra over a range of stocking densities. Cultures were initially stocked with equal proportions of each species, but after three weeks of growth the proportion of Oedogonium had increased to at least 96% (±7 S.E.) in Oedogonium-Spirogyra bi-cultures, 86% (±16 S.E.) in Oedogonium-Cladophora bi-cultures and 82% (±18 S.E.) in polycultures. The high productivity, bioenergy potential and competitive dominance of Oedogonium make this species an ideal freshwater macroalgal target for large-scale production and a valuable biomass source for bioenergy applications. These results demonstrate that freshwater macroalgae are thus far an under-utilised feedstock with much potential for biomass applications.

Aggression and feeding of hatchery-reared and naturally reared steelhead (Oncorhynchus mykiss) fry in a laboratory flume and a comparison with observations in natural streams

USGS Publications Warehouse

Riley, S.C.; Tatara, C.P.; Scheurer, J.A.

2005-01-01

We quantified the aggression and feeding of naturally reared steelhead (Oncorhynchus mykiss) fry stocked into a laboratory flume with naturally reared fry or hatchery-reared fry from conventional and enriched rearing environments at three densities in the presence and absence of predators, and compared the aggression and feeding observed in the flume to that observed in two streams. Steelhead fry attack rate increased with density and was reduced in the presence of predators, but was not affected by rearing treatment. Threat rate appeared to increase with density and was significantly affected by rearing treatment combination, but was not significantly affected by predator presence. Feeding rate was not affected by density or rearing treatment, but was reduced in the presence of predators. The rate of aggression by steelhead fry in two streams was lower than that observed in the laboratory and did not increase with density. Rates of aggression and feeding of hatchery-reared and wild steelhead fry were not significantly different in the streams. Overall, we found no evidence that hatchery rearing environments caused higher aggression in steelhead fry. Laboratory observations of salmonid aggression, particularly at high density, may not reflect aggression levels in the wild. ?? 2005 NRC.

Sign realized jump risk and the cross-section of stock returns: Evidence from China's stock market.

PubMed

Chao, Youcong; Liu, Xiaoqun; Guo, Shijun

2017-01-01

Using 5-minute high frequency data from the Chinese stock market, we employ a non-parametric method to estimate Fama-French portfolio realized jumps and investigate whether the estimated positive, negative and sign realized jumps could forecast or explain the cross-sectional stock returns. The Fama-MacBeth regression results show that not only have the realized jump components and the continuous volatility been compensated with risk premium, but also that the negative jump risk, the positive jump risk and the sign jump risk, to some extent, could explain the return of the stock portfolios. Therefore, we should pay high attention to the downside tail risk and the upside tail risk.

Approach of regionalisation c-stocks in forest soils on a national level

NASA Astrophysics Data System (ADS)

Wellbrock, Nicole; Höhle, Juliane; Dühnelt, Petra; Holzhausen, Marieanna

2010-05-01

Introduction In December 2006, the German government decided to manage forests as carbon sinks to reduce greenhouse gas emissions in accordance with Article 3.4 of the Kyoto Protocol. The National Forest Monitoring data contribute to the fulfilment of these reporting commitments. In Germany, National Forest Monitoring includes the systematical extensive National Soil Condition Survey (BZE) and the detailed case studies (Level-II) which determine the processes within forests. This complex monitoring system is appropriate to Germany's greenhouse gas reporting (THG 2008 to 2012). The representative BZE plots can be used to obtain regional data for the National Carbon Stock Inventory. Here, an approach adopting a combination of geostatistics and regression analysis is preferred. The difficulty of showing the statistical significance of expected small changes while carbon stocks are generally high is one of the major challenges in carbon stock monitoring. However, through intensive preparation and cooperation with the forestry authorities of each federal state, the errors uncured in determining changes in carbon stocks in forest soils, which must be stipulated in greenhouse gas monitoring, could be minimised. In contrast to the detailed soil case studies, in which essentially the sources of error occur repeatedly in carbon stock change calculations, the BZE data can be stratified to form plots with homogenous properties, thereby reducing the standard error of estimate. Subsequently, the results of the stratification are projected across Germany, the reporting unit for greenhouse gas monitoring. National Forest Monitoring The BZE represents a national, systematic sampling inventory of the condition of forest soils. The first BZE inventory (BZE I: 1987 to 1993) was carried out on a systematic 8 x 8 km grid on the same sampling plots adopted in the Forest Condition Survey (WZE). In some areas the network of sampling plots involves 1900 grid points. The first BZE I survey was repeated after 15 years, between 2006 and 2008, by the national and the state authorities in cooperation. Afterwards, extensive laboratory and statistical analyses were conducted. Necessary parameters are listed in table 1. Upscaling approach There are different approaches for presenting extensive carbon stock data (Baritz et al., 2006). The availability of georeference plots means one can merge the point data with map data. In Germany, an approach was tested that used homogenous soil areas und plot-information from the national soil inventory. For every soil area c-stocks were regionalised. Only information form BZE-plots were involved which were characteristic for the soil area. The indicators were soil type and substrate class. For every soil area the forest areas were taken in account to calculate c-stock per forest area. The sum of every c-stock per soil area is the c-stock in forest soils of Germany. Tab.1: List of parameters for the carbon inventory (BZE II) Components Parameters Point level Field sampling Width of depth classes, Fine roots, humus (< 2 cm), dry bulk density, stone content, area of humus layer sampled, height a.s.l., litterfall, deadwood (from 10 cm) Analysis C content, fine soil fraction, weight of humus layer, Carbon stock calculations Carbon stock Regional Level Plot Soil type, parent material, vegetation type or forest Regionalisation Soil and land use maps, statistical models, ecological regions, digital elevation models, climate regions

Complexity and multifractal behaviors of multiscale-continuum percolation financial system for Chinese stock markets

NASA Astrophysics Data System (ADS)

Zeng, Yayun; Wang, Jun; Xu, Kaixuan

2017-04-01

A new financial agent-based time series model is developed and investigated by multiscale-continuum percolation system, which can be viewed as an extended version of continuum percolation system. In this financial model, for different parameters of proportion and density, two Poisson point processes (where the radii of points represent the ability of receiving or transmitting information among investors) are applied to model a random stock price process, in an attempt to investigate the fluctuation dynamics of the financial market. To validate its effectiveness and rationality, we compare the statistical behaviors and the multifractal behaviors of the simulated data derived from the proposed model with those of the real stock markets. Further, the multiscale sample entropy analysis is employed to study the complexity of the returns, and the cross-sample entropy analysis is applied to measure the degree of asynchrony of return autocorrelation time series. The empirical results indicate that the proposed financial model can simulate and reproduce some significant characteristics of the real stock markets to a certain extent.

Elevated elephant density does not improve ecotourism opportunities: convergence in social and ecological objectives.

PubMed

Maciejewski, Kristine; Kerley, Graham I H

2014-07-01

In order to sustainably conserve biodiversity, many protected areas, particularly private protected areas, must find means of self-financing. Ecotourism is increasingly seen as a mechanism to achieve such financial sustainability. However, there is concern that ecotourism operations are driven to achieve successful game-viewing, influencing the management of charismatic species. An abundance of such species, including the African elephant (Loxodonta africana), has been stocked in protected areas under the assumption that they will increase ecotourism value. At moderate to high densities, the impact of elephants is costly; numerous studies have documented severe changes in biodiversity through the impacts of elephants. Protected areas that focus on maintaining high numbers of elephants may therefore face a conflict between socioeconomic demands and the capacity of ecological systems. We address this conflict by analyzing tourist elephant-sighting records from six private and one statutory protected area, the Addo Elephant National Park (AENP), in the Eastern Cape Province of South Africa, in relation to elephant numbers. We found no relationship between elephant density and elephant-viewing success. Even though elephant density in the AENP increased over time, a hierarchical partitioning analysis indicated that elephant density was not a driver of tourist numbers. In contrast, annual tourist numbers for the AENP were positively correlated with general tourist numbers recorded for South Africa. Our results indicate that the socioeconomic and ecological requirements of protected areas in terms of tourism and elephants, respectively, converge. Thus, high elephant densities and their associated ecological costs are not required to support ecotourism operations for financial sustainability. Understanding the social and ecological feedbacks that dominate the dynamics of protected areas, particularly within private protected areas, can help to elucidate the management challenges of minimizing ecological trade-offs while meeting ecotourist demands and achieving sustainability.

Exploration Feeding and Higher Space Allocation Improve Welfare of Growing-Finishing Pigs.

PubMed

Vermeer, Herman M; Dirx-Kuijken, Nienke C P M M; Bracke, Marc B M

2017-04-29

Lack of environmental enrichment and high stocking densities in growing-finishing pigs can lead to adverse social behaviors directed to pen mates, resulting in skin lesions, lameness, and tail biting. The objective of the study was to improve animal welfare and prevent biting behavior in an experiment with a 2 × 2 × 2 factorial design on exploration feeding, stocking density, and sex. We kept 550 pigs in 69 pens from 63 days to 171 days of life. Pigs were supplemented with or without exploration feeding, kept in groups of seven (1.0 m²/pig) or nine animals (0.8 m²/pig) and separated per sex. Exploration feeding provided small amounts of feed periodically on the solid floor. Skin lesion scores were significantly lower in pens with exploration feeding ( p = 0.028, p < 0.001, p < 0.001 for front, middle, and hind body), in pens with high compared to low space allowance ( p = 0.005, p = 0.006, p < 0.001 for front, middle and hind body), and in pens with females compared to males ( p < 0.001, p = 0.005, p < 0.001 for front, middle and hind body). Males with exploration feeding had fewer front skin lesions than females with exploration feeding ( p = 0.022). Pigs with 1.0 m² compared to 0.8 m² per pig had a higher daily gain of 27 g per pig per day ( p = 0.04) and males compared to females had a higher daily gain of 39 g per pig per day ( p = 0.01). These results indicate that exploration feeding might contribute to the development of a more welfare-friendly pig husbandry with intact tails in the near future.

Evaluation of forest structure, biomass and carbon sequestration in subtropical pristine forests of SW China.

PubMed

Nizami, Syed Moazzam; Yiping, Zhang; Zheng, Zheng; Zhiyun, Lu; Guoping, Yang; Liqing, Sha

2017-03-01

Very old natural forests comprising the species of Fagaceae (Lithocarpus xylocarpus, Castanopsis wattii, Lithocarpus hancei) have been prevailing since years in the Ailaoshan Mountain Nature Reserve (AMNR) SW China. Within these forest trees, density is quite variable. We studied the forest structure, stand dynamics and carbon density at two different sites to know the main factors which drives carbon sequestration process in old forests by considering the following questions: How much is the carbon density in these forest trees of different DBH (diameter at breast height)? How much carbon potential possessed by dominant species of these forests? How vegetation carbon is distributed in these forests? Which species shows high carbon sequestration? What are the physiochemical properties of soil in these forests? Five-year (2005-2010) tree growth data from permanently established plots in the AMNR was analysed for species composition, density, stem diameter (DBH), height and carbon (C) density both in aboveground and belowground vegetation biomass. Our study indicated that among two comparative sites, overall 54 species of 16 different families were present. The stem density, height, C density and soil properties varied significantly with time among the sites showing uneven distribution across the forests. Among the dominant species, L. xylocarpus represents 30% of the total carbon on site 1 while C. wattii represents 50% of the total carbon on site 2. The average C density ranged from 176.35 to 243.97 t C ha -1 . The study emphasized that there is generous degree to expand the carbon stocking in this AMNR through scientific management gearing towards conservation of old trees and planting of potentially high carbon sequestering species on good site quality areas.

Imputing forest carbon stock estimates from inventory plots to a nationally continuous coverage

PubMed Central

2013-01-01

The U.S. has been providing national-scale estimates of forest carbon (C) stocks and stock change to meet United Nations Framework Convention on Climate Change (UNFCCC) reporting requirements for years. Although these currently are provided as national estimates by pool and year to meet greenhouse gas monitoring requirements, there is growing need to disaggregate these estimates to finer scales to enable strategic forest management and monitoring activities focused on various ecosystem services such as C storage enhancement. Through application of a nearest-neighbor imputation approach, spatially extant estimates of forest C density were developed for the conterminous U.S. using the U.S.’s annual forest inventory. Results suggest that an existing forest inventory plot imputation approach can be readily modified to provide raster maps of C density across a range of pools (e.g., live tree to soil organic carbon) and spatial scales (e.g., sub-county to biome). Comparisons among imputed maps indicate strong regional differences across C pools. The C density of pools closely related to detrital input (e.g., dead wood) is often highest in forests suffering from recent mortality events such as those in the northern Rocky Mountains (e.g., beetle infestations). In contrast, live tree carbon density is often highest on the highest quality forest sites such as those found in the Pacific Northwest. Validation results suggest strong agreement between the estimates produced from the forest inventory plots and those from the imputed maps, particularly when the C pool is closely associated with the imputation model (e.g., aboveground live biomass and live tree basal area), with weaker agreement for detrital pools (e.g., standing dead trees). Forest inventory imputed plot maps provide an efficient and flexible approach to monitoring diverse C pools at national (e.g., UNFCCC) and regional scales (e.g., Reducing Emissions from Deforestation and Forest Degradation projects) while allowing timely incorporation of empirical data (e.g., annual forest inventory). PMID:23305341

Effects of fish movement assumptions on the design of a marine protected area to protect an overfished stock.

PubMed

Cornejo-Donoso, Jorge; Einarsson, Baldvin; Birnir, Bjorn; Gaines, Steven D

2017-01-01

Marine Protected Areas (MPA) are important management tools shown to protect marine organisms, restore biomass, and increase fisheries yields. While MPAs have been successful in meeting these goals for many relatively sedentary species, highly mobile organisms may get few benefits from this type of spatial protection due to their frequent movement outside the protected area. The use of a large MPA can compensate for extensive movement, but testing this empirically is challenging, as it requires both large areas and sufficient time series to draw conclusions. To overcome this limitation, MPA models have been used to identify designs and predict potential outcomes, but these simulations are highly sensitive to the assumptions describing the organism's movements. Due to recent improvements in computational simulations, it is now possible to include very complex movement assumptions in MPA models (e.g. Individual Based Model). These have renewed interest in MPA simulations, which implicitly assume that increasing the detail in fish movement overcomes the sensitivity to the movement assumptions. Nevertheless, a systematic comparison of the designs and outcomes obtained under different movement assumptions has not been done. In this paper, we use an individual based model, interconnected to population and fishing fleet models, to explore the value of increasing the detail of the movement assumptions using four scenarios of increasing behavioral complexity: a) random, diffusive movement, b) aggregations, c) aggregations that respond to environmental forcing (e.g. sea surface temperature), and d) aggregations that respond to environmental forcing and are transported by currents. We then compare these models to determine how the assumptions affect MPA design, and therefore the effective protection of the stocks. Our results show that the optimal MPA size to maximize fisheries benefits increases as movement complexity increases from ~10% for the diffusive assumption to ~30% when full environment forcing was used. We also found that in cases of limited understanding of the movement dynamics of a species, simplified assumptions can be used to provide a guide for the minimum MPA size needed to effectively protect the stock. However, using oversimplified assumptions can produce suboptimal designs and lead to a density underestimation of ca. 30%; therefore, the main value of detailed movement dynamics is to provide more reliable MPA design and predicted outcomes. Large MPAs can be effective in recovering overfished stocks, protect pelagic fish and provide significant increases in fisheries yields. Our models provide a means to empirically test this spatial management tool, which theoretical evidence consistently suggests as an effective alternative to managing highly mobile pelagic stocks.

Dynamics of organic carbon stock of Estonian arable and grassland peat soils

NASA Astrophysics Data System (ADS)

Kauer, Karin; Tammik, Kerttu; Penu, Priit

2016-04-01

Peat soils represent globally a major reserve of soil organic carbon (SOC). Estimation of changes in SOC stocks is important for understanding soil carbon sequestration and dynamics of greenhouse gas emissions. The aim of this study was to estimate the SOC stock of Estonian agricultural peat soils and SOC stock change depending on land use type (arable land and long-term grasslands (over 5 years)). The soils were classified as Histosols according to WRB classification. Generally the arable land was used for growing cereals, oilseed rape, legumes and used as ley in crop rotation. The main technique of soil cultivation was ploughing. During 2002-2015 the soil samples of 0-20 cm soil layer (one average soil sample per 1-5 ha) were collected. The SOC content was measured by NIRS method. The SOC stock was calculated by assuming that soil mean bulk density is 0.3 g cm-3. The SOC stock change in arable land was estimated during 3-13 years (N=91) and in grassland 4-13 year (N=163). The average SOC content of peat soils varied from 150.6 to 549.0 mg g-1. The initial SOC stock of arable land was 271.3 t ha-1 and of grassland 269.3 t ha-1. The SOC stock declined in arable peat soils faster (-2.57 t ha-1 y-1) compared to the changes in grassland peat soils (-0.67 t ha-1 y-1). According to the length of the study period the SOC stock change per year varied from -5.14 to 6.64 t ha-1 y-1 in grasslands and from -14.78 to 0.83 t ha-1 y-1 in arable land, although there was no clear relationship between the SOC stock change and the length of the study period. More detailed information about the properties of agricultural land and land use history is needed to analyse the causes of the SOC stock changes in agricultural peat soils. However, from the current research we can conclude that the SOC stock of arable and grassland peat soils is declining during the cultivation. These decreases are important to specify when considering the role of peat soils in atmospheric greenhouse gas balances considering peat soils spatial variability related to regional and local differences in ecology, hydrology and climate.

Can investor sentiment be used to predict the stock price? Dynamic analysis based on China stock market

NASA Astrophysics Data System (ADS)

Guo, Kun; Sun, Yi; Qian, Xin

2017-03-01

With the development of the social network, the interaction between investors in stock market became more fast and convenient. Thus, investor sentiment which can influence their investment decisions may be quickly spread and magnified through the network, and to a certain extent the stock market can be affected. This paper collected the user comments data from a popular professional social networking site of China stock market called Xueqiu, then the investor sentiment data can be obtained through semantic analysis. The dynamic analysis on relationship between investor sentiment and stock market is proposed based on Thermal Optimal Path (TOP) method. The results show that the sentiment data was not always leading over stock market price, and it can be used to predict the stock price only when the stock has high investor attention.

Sign realized jump risk and the cross-section of stock returns: Evidence from China's stock market

PubMed Central

Chao, Youcong; Liu, Xiaoqun; Guo, Shijun

2017-01-01

Using 5-minute high frequency data from the Chinese stock market, we employ a non-parametric method to estimate Fama-French portfolio realized jumps and investigate whether the estimated positive, negative and sign realized jumps could forecast or explain the cross-sectional stock returns. The Fama-MacBeth regression results show that not only have the realized jump components and the continuous volatility been compensated with risk premium, but also that the negative jump risk, the positive jump risk and the sign jump risk, to some extent, could explain the return of the stock portfolios. Therefore, we should pay high attention to the downside tail risk and the upside tail risk. PMID:28771514

Hypotheses of Spatial Stock Structure in Orange Roughy Hoplostethus atlanticus Inferred from Diet, Feeding, Condition, and Reproductive Activity

PubMed Central

Dunn, Matthew R.; Forman, Jeffrey S.

2011-01-01

We evaluate hypotheses for meso-scale spatial structure in an orange roughy (Hoplostethus atlanticus) stock using samples collected during research trawl surveys off the east coast of New Zealand. Distance-based linear models and generalised additive models were used to identify the most significant biological, environmental, and temporal predictors of variability in diet, proportion of stomachs containing prey, standardised weight of prey, fish somatic weight, fish total weight, and reproductive activity. The diet was similar to that observed elsewhere, and varied with ontogeny, depth, and surface water temperature. Smaller sized and female orange roughy in warmer bottom water were most likely to contain food. Fish condition and reproductive activity were highest at distances more than 20 km from the summit of the hills. Trawl survey catches indicated greater orange roughy densities in hill strata, suggesting hill habitat was favoured. However, analyses of feeding, condition, and reproductive activity indicated hill fish were not superior, despite fish densities on hills being reduced by fishing which, in principle, should have reduced intra-specific competition for food and other resources. Hypotheses for this result include: (1) fish in relatively poor condition visit hills to feed and regain condition and then leave, or (2) commercial fishing has disturbed feeding aggregations and/or caused habitat damage, making fished hills less productive. Mature orange roughy were observed on both flat and hill habitat during periods outside of spawning, and if this spatial structure was persistent then a proportion of the total spawning stock biomass would remain unavailable to fisheries targeting hills. Orange roughy stock assessments informed only by data from hills may well be misleading. PMID:22069464

Changes in land cover and vegetation carbon stocks in Andalusia, Southern Spain (1956-2007).

PubMed

Muñoz-Rojas, M; De la Rosa, D; Zavala, L M; Jordán, A; Anaya-Romero, M

2011-06-15

Land use has significantly changed during the recent decades at global and local scale, while the importance of ecosystems as sources/sinks of C has been highlighted, emphasizing the global impact of land use changes. Land use changes can increase C loss rates which are extremely difficult to reverse, in the short term, opposite to organic carbon (OC) which accumulates in soil in the long-term. The aim of this research is to improve and test methodologies to assess land cover change (LCC) dynamics and temporal and spatial variability in C stored in vegetation at a wide scale. LCCs between 1956 and 2007 in Andalusia (Southern Spain) were selected for this pilot study, assessed by comparison of spatial data from 1956 to 2007 and were reclassified following land cover flows (LCFs) reported in major areas in Europe. Carbon vegetation densities were related to land cover, and C vegetation stocks for 1956 and 2007 were calculated by multiplying C density for each land cover class with land cover areas. The study area has supported important changes during the studied period with significant consequences for vegetation C stocks, mainly due to afforestation and intensification of agriculture, resulting in a total vegetation C stock of 156.08Tg in 2007, with an increase of 17.24Tg since 1956. This study demonstrates the importance of LCC for C sequestration in vegetation from Mediterranean areas, highlighting possible directions for management policies in order to mitigate climate change as well as promoting land conservation. The methodologies and information generated in this project will be a useful basis for designing land management strategies helpful for decision makers. Copyright © 2011 Elsevier B.V. All rights reserved.

A significant carbon sink in temperate forests in Beijing: based on 20-year field measurements in three stands.

PubMed

Zhu, JianXiao; Hu, XueYang; Yao, Hui; Liu, GuoHua; Ji, ChenJun; Fang, JingYun

2015-11-01

Numerous efforts have been made to characterize forest carbon (C) cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three permanent temperate forest plots (birch, oak and pine forest) during 2011–2014, and calculated the changes of the components of the C cycle related to the measurements during 1992–1994 at Mt. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011–2014 were significantly larger than those in 1992–1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha-1 in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-1; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-1. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.

Pasture-scale methane emissions of grazing cattle

USDA-ARS?s Scientific Manuscript database

Grazing cattle are mobile point sources of methane and present challenges to quantify emissions using noninterfering micrometeorological methods. Stocking density is low and cattle can bunch up or disperse over a wide area, so knowing cattle locations is critical. The methane concentration downwind ...

Stock price prediction using geometric Brownian motion

NASA Astrophysics Data System (ADS)

Farida Agustini, W.; Restu Affianti, Ika; Putri, Endah RM

2018-03-01

Geometric Brownian motion is a mathematical model for predicting the future price of stock. The phase that done before stock price prediction is determine stock expected price formulation and determine the confidence level of 95%. On stock price prediction using geometric Brownian Motion model, the algorithm starts from calculating the value of return, followed by estimating value of volatility and drift, obtain the stock price forecast, calculating the forecast MAPE, calculating the stock expected price and calculating the confidence level of 95%. Based on the research, the output analysis shows that geometric Brownian motion model is the prediction technique with high rate of accuracy. It is proven with forecast MAPE value ≤ 20%.

Amazon peatlands: quantifying ecosytem's stocks, GHG fluxes and their microbial connections

NASA Astrophysics Data System (ADS)

Cadillo-Quiroz, Hinsby; Lähteenoja, Outi; Buessecker, Steffen; van Haren, Joost

2017-04-01

Reports of hundreds of peatlands across basins in the West and Central Amazon suggest they play an important, previously not considered regional role in organic carbon (OC) and GHG dynamics. Amazon peatlands store ˜3-6 Gt of OC in their waterlogged soils with strong potential for conversion and release of GHG, in fact our recent, and others', efforts have confirmed variable levels of GHG emissions (CO2, N2O, CH4), as well as variable microbial communities across rich to poor soil peatlands. Here, we report early results of quantification of different components making up the aboveground C stocks, the rates and paths for GHG release, and microbial organisms occurring in three ecologically distinct peatland types in the Pastaza-Marañon region of the Peruvian Amazon. Evaluations were done in duplicated continuous monitoring plots established since 2015 at a "palm swamp" (PS), poor "pole forest" (pPF) and a rich "forested" (rF) peatlands. Although overall vegetation "structure" with a few dominant plus several low frequency species was common across the three sites, their botanical composition and tree density was highly contrasting. Aboveground C stocks content showed the following order among sites: rF>PS>pPF, and hence we tested whether this differences can have a direct effect on CH4 emissions rates. CH4 emissions rates from soils were observed in average at 11, 6, and 0.8 mg-C m-2 h-1for rF, PS, and pPF respectively. However, these estimated fluxes needed to be revised when we develop quantifications of CH4 emissions from tree stems. Tree stem fluxes were detected showing a broad variation with nearly nill emissions in some species all the way to maximum fluxes near to ˜90 mg-C m-2 h-1 in other species. Mauritia flexuosa, a highly dominant palm species in PS and ubiquitous to the region, showed the highest ranges of CH4 flux. In the PS site, overall CH4 flux estimate increased by ˜50% when including stem emission weighted by trees' species, density and heights. Flux estimates in p PF did not had a significant change. Analysis across species in the study sites, plus other satellite sites, suggest that in sites stem flux emissions might be conserved with some genera in the Aracaceae, Euphorbiaceae, and Sapotaceae families showing a large emitters capacity. Further characterization also showed that CH4 flux emission from the stems decreases generally with height, suggesting a diffusion constrained stem flux, which seems limited by soil CH4 concentration and wood density. Finally, microbial community composition and methanogenic activity also showed contrasting patterns across sites, with pH being one of the major determinants. GHG producing organisms were detected in different proportions and types across study sites, and importantly methanogenic Archaea closely tracked observed differences of CH4 flux among sites. Nevertheless, the link between vegetation type and density still remain under assessment in our efforts

Reductions of plant cover induced by sheep grazing change the above-belowground partition and chemistry of organic C stocks in arid rangelands of Patagonian Monte, Argentina.

PubMed

Larreguy, C; Carrera, A L; Bertiller, M B

2017-09-01

The objective of this study was to estimate the size and chemical quality of the total organic C stock and its partition between above-belowground plant parts and soil at sites with different plant cover induced by sheep grazing in the arid Patagonian Monte. This study was conducted at six representative sites with increasing signs of canopy disturbance attributed to grazing pressure. We used faeces density as a proxy of grazing pressure at each site. We assessed the total plant cover, shrub and perennial grass cover, total standing aboveground biomass (AGB), litter mass and belowground biomass (BGB) at each site. We further estimated the content of organic C, lignin and soluble phenols in plant compartments and the content of organic C, organic C in humic substances (recalcitrant C) and water soluble C (labile C) in soil at each site. Total plant cover was significantly related to grazing pressure. Standing AGB and litter mass decreased with increasing canopy disturbance while BGB did not vary across sites. Total organic C stock and the organic C stock in standing AGB increased with increasing total plant, shrub, and perennial grass cover. The organic C stock in litter mass increased with increasing total plant and shrub cover, while the organic C stock in BGB did not vary across sites. Lignin content in plant compartments increased with increasing total and shrub cover, while soluble phenols content did not change across sites. The organic C stock and the water soluble C content in soil were positively associated with perennial grass cover. Changes in total plant cover induced by grazing pressure negatively affected the size of the total organic C stock, having minor impact on the size of belowground than aboveground components. The reduction of perennial grass cover was reflected in decreasing chemical quality of the organic C stock in soil. Accordingly, plant managerial strategies should not only be focused on the amount of organic C sequestered but also on the chemical quality of organic C stocks since C chemistry could have an important impact on ecosystem functioning. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stocking, growth, and yield of oak stands

Treesearch

Samuel F. Gingrich

1971-01-01

An appraisal of stocking in even-aged upland oak stands is a prerequisite for determining the cultural needs of a given stand. Most oak stands have sufficient stocking to utilize the site, but are deficient in high-quality trees. Thinning such stands offers a good opportunity to upgrade the relative quality of the growing stock and enhance the growth and yield...

Carbon stock corridors to mitigate climate change and promote biodiversity in the tropics

NASA Astrophysics Data System (ADS)

Jantz, Patrick; Goetz, Scott; Laporte, Nadine

2014-02-01

A key issue in global conservation is how biodiversity co-benefits can be incorporated into land use and climate change mitigation activities, particularly those being negotiated under the United Nations to reduce emissions from tropical deforestation and forest degradation. Protected areas have been the dominant strategy for tropical forest conservation and they have increased substantially in recent decades. Avoiding deforestation by preserving carbon stored in vegetation between protected areas provides an opportunity to mitigate the effects of land use and climate change on biodiversity by maintaining habitat connectivity across landscapes. Here we use a high-resolution data set of vegetation carbon stock to map corridors traversing areas of highest biomass between protected areas in the tropics. The derived corridors contain 15% of the total unprotected aboveground carbon in the tropical region. A large number of corridors have carbon densities that approach or exceed those of the protected areas they connect, suggesting these are suitable areas for achieving both habitat connectivity and climate change mitigation benefits. To further illustrate how economic and biological information can be used for corridor prioritization on a regional scale, we conducted a multicriteria analysis of corridors in the Legal Amazon, identifying corridors with high carbon, high species richness and endemism, and low economic opportunity costs. We also assessed the vulnerability of corridors to future deforestation threat.

Population-regulating processes during the adult phase in flatfish

NASA Astrophysics Data System (ADS)

Rijnsdorp, A. D.

Flatfish support major fisheries and the study of regulatory processes are of paramount importance for evaluating the resilience of the resource to exploitation. This paper reviews the evidence for processes operating during the adult phase that may 1. generate interannual variability in recruitment; 2. contribute to population regulation through density-dependent growth, density-dependent ripening of adults and density-dependent egg production. With regard to (1), there is evidence that in the adult phase processes do occur that may generate recruitment variability through variation in size-specific fecundity, contraction of spawning season, reduction in egg quality, change in sex ratio and size composition of the adult population. However, time series of recruitment do not provide support for this hypothesis. With regard to (2), there is ample evidence that exploitation of flatfish coincides with an increase in growth, although the mechanisms involved are not always clear. The presence of density-dependent growth in the adult phase of unexploited populations appears to be the most likely explanation in some cases. From the early years of exploitation of flatfish stocks inhabiting cold waters, evidence exists that adult fish do not spawn each year. Fecundity schedules show annual variations, but the available information suggests that size-specific fecundity is stable over a broad range of population abundance and may only decrease at high population abundance. The analysis is complicated by the possibility of a trade-off between egg numbers and egg size. Nevertheless, a density-dependent decrease in growth will automatically result in a decrease in absolute fecundity because of the reduced body size. The potential contribution of these regulatory effects on population regulation is explored. Results indicate that density-dependent ripening and absolute fecundity, mediated through density-dependent growth, may control recruitment at high levels of population abundance. The effect of a density-dependent decrease in size-specific fecundity seems to play a minor role, although this role may become important at extremely high levels of population abundance.

Characterising the fate of nitrogenous waste from the sea-cage aquaculture of spiny lobsters using numerical modelling.

PubMed

Lee, Soxi; Hartstein, Neil D; Jeffs, Andrew

2015-06-01

Although the aquaculture of spiny lobsters has been expanding since the 1970s, very little is known about the potential environmental impacts on water quality of this activity. This study quantified the production of dissolved inorganic nitrogen (DIN) from Australasian red spiny lobsters, Jasus edwardsii, in the laboratory, and these data were then used in a numerical model to predict the dispersal pattern of DIN from a hypothetical commercial spiny lobster farm for a coastal site where such a farm would typically be located. Modelling scenarios were set up with combinations of two different stocking densities (3 and 5 kg m(-3)), two different diets (mussels and moist artificial diet) and three different feed conversion ratios (FCR = 3, 5 and 28). DIN excretion rate from unfed lobsters in the laboratory on average was 1.10 ± 0.12 μg N g(-1) h(-1) while feeding lobsters on mussels and artificial diet increased DIN excretion significantly by around eightfold and twofold, respectively. Ammonia was consistently the dominant contributor to measured DIN output from lobsters. Modelling results indicated that the mean elevated DIN from a hypothetical farm where the lobsters were fed with mussels ranged from 7 up to 20 μg N L(-1) with increasing stocking density and FCR and was 30-150 % higher than the mean elevated DIN resulting from lobsters fed with artificial diet. Overall, the results indicated that DIN output from the hypothetical spiny lobster sea-cage farming is unlikely to be problematic using the FCR, stocking density, and the number of cages modelled at the coastal site in this study. Furthermore, feeding lobsters with artificial diet can help maintain a lower DIN output than seafood, such as mussels or trash fish.

Larvivorous fish for preventing malaria transmission.

PubMed

Walshe, Deirdre P; Garner, Paul; Abdel-Hameed Adeel, Ahmed A; Pyke, Graham H; Burkot, Tom

2013-12-10

Adult anopheline mosquitoes transmit Plasmodium parasites that cause malaria. Some fish species eat mosquito larvae and pupae. In disease control policy documents, the World Health Organization includes biological control of malaria vectors by stocking ponds, rivers, and water collections near where people live with larvivorous fish to reduce Plasmodium parasite transmission. The Global Fund finances larvivorous fish programmes in some countries, and, with increasing efforts in eradication of malaria, policy makers may return to this option. We therefore assessed the evidence base for larvivorous fish programmes in malaria control. Our main objective was to evaluate whether introducing larvivorous fish to anopheline breeding sites impacts Plasmodium parasite transmission. Our secondary objective was to summarize studies evaluating whether introducing larvivorous fish influences the density and presence of Anopheles larvae and pupae in water sources, to understand whether fish can possibly have an effect. We attempted to identify all relevant studies regardless of language or publication status (published, unpublished, in press, or ongoing). We searched the following databases: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; CABS Abstracts; LILACS; and the metaRegister of Controlled Trials (mRCT) until 18 June 2013. We checked the reference lists of all studies identified by the above methods. We also examined references listed in review articles and previously compiled bibliographies to look for eligible studies. Randomized controlled trials and non-randomized controlled trials, including controlled before-and-after studies, controlled time series and controlled interrupted time series studies from malaria-endemic regions that introduced fish as a larvicide and reported on malaria in the community or the density of the adult anopheline population. In the absence of direct evidence of an effect on transmission, we carried out a secondary analysis on studies that evaluated the effect of introducing larvivorous fish on the density or presence of immature anopheline mosquitoes (larvae and pupae forms) in community water sources to determine whether this intervention has any potential in further research on control of malaria vectors. Three review authors screened abstracts and examined potentially relevant studies by using an eligibility form. Two review authors independently extracted data and assessed risk of bias of included studies. If relevant data were unclear or were not reported, we wrote to the trial authors for clarification. We presented data in tables, and we summarized studies that evaluated the effects of fish introduction on anopheline immature density or presence, or both. We used GRADE to summarize evidence quality. We also examined whether the authors of included studies reported on any possible adverse impact of larvivorous fish introduction on non-target native species. We found no reliable studies that reported the effects of introducing larvivorous fish on malaria infection in nearby communities, on entomological inoculation rate, or on adult Anopheles density.For the secondary analysis, we examined the effects of introducing larvivorous fish on the density and presence of anopheline larvae and pupae in community water sources. We included 12 small studies, with follow-up from 22 days to five years. Studies were conducted in a variety of settings, including localized water bodies (such as wells, domestic water containers, fishponds, and pools; six studies), riverbed pools below dams (two studies), rice field plots (three studies), and water canals (two studies). All studies were at high risk of bias.The research was insufficient to determine whether larvivorous fish reduce the density of Anopheles larvae and pupae (nine studies, unpooled data, very low quality evidence). Some studies with high stocking levels of fish seemed to arrest the increase in immature anopheline populations, or to reduce the number of immature anopheline mosquitoes, compared with controls. However, this finding was not consistent, and in studies that showed a decrease in immature anopheline populations, the effect was not consistently sustained. Larvivorous fish may reduce the number of water sources with Anopheles larvae and pupae (five studies, unpooled data, low quality evidence).None of the included studies reported effects of larvivorous fish on local native fish populations or other species. Reliable research is insufficient to show whether introducing larvivorous fish reduces malaria transmission or the density of adult anopheline mosquito populations.In research examining the effects on immature anopheline stages of introducing fish to potential malaria vector breeding sites (localized water bodies such as wells and domestic water sources, rice field plots, and water canals) weak evidence suggests an effect on the density or presence of immature anopheline mosquitoes with high stocking levels of fish, but this finding is by no means consistent. We do not know whether this translates into health benefits, either with fish alone or with fish combined with other vector control measures. Our interpretation of the current evidence is that countries should not invest in fish stocking as a larval control measure in any malaria transmission areas outside the context of carefully controlled field studies or quasi-experimental designs. Research could also usefully examine the effects on native fish and other non-target species.

Sampling for Soil Carbon Stock Assessment in Rocky Agricultural Soils

NASA Technical Reports Server (NTRS)

Beem-Miller, Jeffrey P.; Kong, Angela Y. Y.; Ogle, Stephen; Wolfe, David

2016-01-01

Coring methods commonly employed in soil organic C (SOC) stock assessment may not accurately capture soil rock fragment (RF) content or soil bulk density (rho (sub b)) in rocky agricultural soils, potentially biasing SOC stock estimates. Quantitative pits are considered less biased than coring methods but are invasive and often cost-prohibitive. We compared fixed-depth and mass-based estimates of SOC stocks (0.3-meters depth) for hammer, hydraulic push, and rotary coring methods relative to quantitative pits at four agricultural sites ranging in RF content from less than 0.01 to 0.24 cubic meters per cubic meter. Sampling costs were also compared. Coring methods significantly underestimated RF content at all rocky sites, but significant differences (p is less than 0.05) in SOC stocks between pits and corers were only found with the hammer method using the fixed-depth approach at the less than 0.01 cubic meters per cubic meter RF site (pit, 5.80 kilograms C per square meter; hammer, 4.74 kilograms C per square meter) and at the 0.14 cubic meters per cubic meter RF site (pit, 8.81 kilograms C per square meter; hammer, 6.71 kilograms C per square meter). The hammer corer also underestimated rho (sub b) at all sites as did the hydraulic push corer at the 0.21 cubic meters per cubic meter RF site. No significant differences in mass-based SOC stock estimates were observed between pits and corers. Our results indicate that (i) calculating SOC stocks on a mass basis can overcome biases in RF and rho (sub b) estimates introduced by sampling equipment and (ii) a quantitative pit is the optimal sampling method for establishing reference soil masses, followed by rotary and then hydraulic push corers.

Steelhead Supplementation in Idaho Rivers, 2000 Annual Report.

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

Byrne, Alan

In 2000, we continued our assessment of the Sawtooth Hatchery steelhead stock to reestablish natural populations in Beaver and Frenchman creeks in the upper Salmon River. We stocked both streams with 15 pair of hatchery adults and estimated the potential smolt production from the 1999 outplant. I estimated that about nine smolts per female could be produced in both streams from the 1999 outplant. The smolt-to-adult return would need to exceed 20% to return two adults at this level of production. In the Red River drainage, we stocked Dworshak hatchery stock fingerlings and smolts, from 1993 to 1999, to assessmore » which life-stage produces more progeny when the adults return to spawn. In 2000, we operated the Red River weir to trap adults that returned from these stockings, but none were caught from either group. We continued to monitor wild steelhead populations in the Lochsa and Selway river drainages. We estimated that 26 wild adult steelhead returned to Fish Creek. This is the lowest adult escapement we have documented (when the weir was intact all spring) since we began monitoring Fish Creek in 1992. I estimated that nearly 25,000 juvenile steelhead migrated out of Fish Creek this year. Juvenile steelhead densities in Lochsa and Selway tributaries were similar to those observed in 1999. In 2000, we obtained funding for a DNA analysis to assess Idaho's steelhead stock structure. We collected fin samples from wild steelhead in 70 streams of the Clearwater, Snake, and Salmon River drainages and from our five hatchery stocks. The DNA analysis was subcontracted to Dr. Jennifer Nielsen, Alaska Biological Science Center, Anchorage, and will be completed in 2001.« less

Biotic and abiotic factors related to lake herring recruitment in the Wisconsin waters of Lake Superior, 1984-1998

USGS Publications Warehouse

Hoff, Michael H.

2004-01-01

Lake Superior lake herring (Coregonus artedi) recruitment to 13-14 months of age in the Wisconsin waters of Lake Superior varied by a factor of 5,233 during 1984-1998. Management agencies have sought models that accurately predict recruitment, but no satisfactory model had previously been developed. Lake herring recruitment was modeled to determine which factors most explained recruitment variability. The Ricker stock-recruitment model derived from only the paired stock and recruit data explained 35% of the variability in the recruitment data. The functional relationship that explained the greatest amount of recruitment variation (93%) included lake herring stock size, lake trout (Salvelinus namaycush) population size, slimy sculpin (Cottus cognatus) biomass, the interaction of mean daily wind speed in April (month of hatch) and lake herring stock size, and mean air temperature in April (when lake herring are 12-months old). Model results were interpreted to mean that lake herring recruitment was affected negatively by: slimy sculpin predation on lake herring ova; predation on age-0 lake herring by lake trout; and adult cannibalism on lake herring larvae, which was reduced by increased wind speed. April temperature was the variable that explained the least amount of variability in recruitment, but lake herring recruitment was positively affected by a warm April, which shortened winter and apparently reduced first-winter mortality. Stock size caused compensatory, density-dependent mortality on lake herring recruits. Management efforts appear best targeted at stock size protection, and empirical data implies that stock size in the Wisconsin waters of the lake should be maintained at 2.1-15.0 adults/ha in spring, bottom-trawl surveys.

Relationships among walleye population characteristics and genetic diversity in northern Wisconsin Lakes

USGS Publications Warehouse

Waterhouse, Matthew D.; Sloss, Brian L.; Isermann, Daniel A.

2014-01-01

The maintenance of genetic integrity is an important goal of fisheries management, yet little is known regarding the effects of management actions (e.g., stocking, harvest regulations) on the genetic diversity of many important fish species. Furthermore, relationships between population characteristics and genetic diversity remain poorly understood. We examined relationships among population demographics (abundance, recruitment, sex ratio, and mean age of the breeding population), stocking intensity, and genetic characteristics (heterozygosity, effective number of alleles, allelic richness, Wright's inbreeding coefficient, effective population size [Ne], mean d2 [a measure of inbreeding], mean relatedness, and pairwise population ΦST estimates) for 15 populations of Walleye Sander vitreus in northern Wisconsin. We also tested for potential demographic and genetic influences on Walleye body condition and early growth. Combinations of demographic variables explained 47.1–79.8% of the variation in genetic diversity. Skewed sex ratios contributed to a reduction in Ne and subsequent increases in genetic drift and relatedness among individuals within populations; these factors were correlated to reductions in allelic richness and early growth rate. Levels of inbreeding were negatively related to both age-0 abundance and mean age, suggesting Ne was influenced by recruitment and generational overlap. A negative relationship between the effective number of alleles and body condition suggests stocking affected underlying genetic diversity of recipient populations and the overall productivity of the population. These relationships may result from poor performance of stocked fish, outbreeding depression, or density-dependent factors. An isolation-by-distance pattern of genetic diversity was apparent in nonstocked populations, but was disrupted in stocked populations, suggesting that stocking affected genetic structure. Overall, demographic factors were related to genetic diversity and stocking appeared to alter allelic frequencies and the genetic structure of Walleye populations in Wisconsin, possibly resulting in disruption of local adaptation.

Alpine Grassland Soil Organic Carbon Stock and Its Uncertainty in the Three Rivers Source Region of the Tibetan Plateau

PubMed Central

Chang, Xiaofeng; Wang, Shiping; Cui, Shujuan; Zhu, Xiaoxue; Luo, Caiyun; Zhang, Zhenhua; Wilkes, Andreas

2014-01-01

Alpine grassland of the Tibetan Plateau is an important component of global soil organic carbon (SOC) stocks, but insufficient field observations and large spatial heterogeneity leads to great uncertainty in their estimation. In the Three Rivers Source Region (TRSR), alpine grasslands account for more than 75% of the total area. However, the regional carbon (C) stock estimate and their uncertainty have seldom been tested. Here we quantified the regional SOC stock and its uncertainty using 298 soil profiles surveyed from 35 sites across the TRSR during 2006–2008. We showed that the upper soil (0–30 cm depth) in alpine grasslands of the TRSR stores 2.03 Pg C, with a 95% confidence interval ranging from 1.25 to 2.81 Pg C. Alpine meadow soils comprised 73% (i.e. 1.48 Pg C) of the regional SOC estimate, but had the greatest uncertainty at 51%. The statistical power to detect a deviation of 10% uncertainty in grassland C stock was less than 0.50. The required sample size to detect this deviation at a power of 90% was about 6–7 times more than the number of sample sites surveyed. Comparison of our observed SOC density with the corresponding values from the dataset of Yang et al. indicates that these two datasets are comparable. The combined dataset did not reduce the uncertainty in the estimate of the regional grassland soil C stock. This result could be mainly explained by the underrepresentation of sampling sites in large areas with poor accessibility. Further research to improve the regional SOC stock estimate should optimize sampling strategy by considering the number of samples and their spatial distribution. PMID:24819054

The forgotten part of carbon cycling: Organic matter storage and turnover in subsoils [SUBSOM

NASA Astrophysics Data System (ADS)

Marschner, B.

2013-12-01

In the past, carbon flux measurements and modelling have mostly considered the topsoil where C-concentrations, root densities and microbial activities are generally highest. However, depending on climate zone and land use, this soil compartment contains only 30-50% of the C-stocks of the first meter. If the deeper subsoil down to 3 m is also considered, the contribution of topsoil carbon stocks to total soil C-pools is only 20-40%. Another distinct property of subsoil organic matter is its high apparent 14C age. The 14C age of bulk soil organic matter below 30 cm depth generally increases continuously indicating mean residence times of several 103 to 104 years. Large pool size and high radiocarbon age suggest that subsoil OM has accumulated at very low rates over very long time periods and therefore appears to be very stable. In a review, several hypotheses for explaining why subsoil SOM is so seemingly old and inert are presented. Then a recently granted German research unit consisting of 9 subprojects from all soil science disciplines is introduced, which addresses these questions using field measurements of C-fluxes, 14C analyses and conducting field and lab experiments. 40-60% of soil C-pools are found below 40 cm depth (Data from Jobbagy & Jackson 2000).

Genetic aspects of the transition from traditional to modern fish farming.

PubMed

Moav, R; Soller, M; Hulata, G

1976-11-01

A theoretical model describing the genetic aspect of the transition from traditional to modern animal husbandry is presented. Traditional races are characterized by high tolerance to harsh environments but a low rate of response to increased management inputs. Modern, artificially-selected breeds are efficient convertors of management inputs to higher production but have a low resistance to harsh environments. Thus, under lowinput traditional husbandry, the traditional races are best adapted, while under modern, high-input husbandry, modern breeds are most productive, and in the intermediate zone, hybrids between the two races are capable of closing the 'profit gap' in the shift from traditional to modern husbandry. The domesticated European, and the Chinese Big-belly races of the common carp were tested under many environmental 'treatments' involving variation in density, polyculture, aeration, feeding and fertilization. The Big-belly showed, as expected, high resistance to the poor 'treatments' but low response to environmental improvement. The European breeds performed best in the higher half of the environmental range and their response rates were highest. The F1 hybrids between the two races excelled in the lower third of the range, exhibiting, there, a high heterosis but only an intermediate rate of response. It was concluded that successful changes from one aquaculture system to another, and particularly the change from traditional to modern husbandry, require a simultaneous search for the most efficient genotype × environment combination and, for each level of modernization of traditional fish farming, the most effective genotype must be identified and utilized. The transition from traditional to modern animal husbandry, including fish farming, is best quantified by the levels of invested inputs, other than labour, that induce higher production of the individual animals. The major management inputs of modern fresh water fish farming are expensive feeding, veterinary care, control of predators, organic and chemical fertilizers that enrich the production of natural fish food, water circulation and aeration. Since all these inputs are rather expensive, the fish have to pay for them by increased production, i.e., faster growth rate. Thus, the sina qua non of such a transition is the availability of animal stocks capable of converting increased inputs into economically attractive increased yields. We are all aware of the very great physiological plasticity of farm animals. In the case of the European carp, for example, the same genetic stocks, raised under high stocking density and low feeding level may gain an average weight of 10 to 20 g per fish in a whole year, while under low density and abundant feeding, they may gain over 2 kg in the same period. Such physiological responsiveness may give the wrong impression that all that is needed for the transition to more modern husbandry are improved environmental circumstances. The object of this paper is to point out that the proper choice and changeover of genotypes is equally important for the succesfull implementation of the usually gradual process of fish farming modernization. This demonstration will be based on results of experiments with the European and Chinese races of the common carp, and their F1 hybrids.

Not all that glitters is RMT in the forecasting of risk of portfolios in the Brazilian stock market

NASA Astrophysics Data System (ADS)

Sandoval, Leonidas; Bortoluzzo, Adriana Bruscato; Venezuela, Maria Kelly

2014-09-01

Using stocks of the Brazilian stock exchange (BM&F-Bovespa), we build portfolios of stocks based on Markowitz's theory and test the predicted and realized risks. This is done using the correlation matrices between stocks, and also using Random Matrix Theory in order to clean such correlation matrices from noise. We also calculate correlation matrices using a regression model in order to remove the effect of common market movements and their cleaned versions using Random Matrix Theory. This is done for years of both low and high volatility of the Brazilian stock market, from 2004 to 2012. The results show that the use of regression to subtract the market effect on returns greatly increases the accuracy of the prediction of risk, and that, although the cleaning of the correlation matrix often leads to portfolios that better predict risks, in periods of high volatility of the market this procedure may fail to do so. The results may be used in the assessment of the true risks when one builds a portfolio of stocks during periods of crisis.

Carbon stocks and dynamics at different successional stages in an Afromontane tropical forest

NASA Astrophysics Data System (ADS)

Nyirambangutse, Brigitte; Zibera, Etienne; Uwizeye, Félicien K.; Nsabimana, Donat; Bizuru, Elias; Pleijel, Håkan; Uddling, Johan; Wallin, Göran

2017-03-01

As a result of different types of disturbance, forests are a mixture of stands at different stages of ecological succession. Successional stage is likely to influence forest productivity and carbon storage, linking the degree of forest disturbance to the global carbon cycle and climate. Although tropical montane forests are an important part of tropical forest ecosystems (ca. 8 %, elevation > 1000 m a.s.l.), there are still significant knowledge gaps regarding the carbon dynamics and stocks of these forests, and how these differ between early (ES) and late successional (LS) stages. This study examines the carbon (C) stock, relative growth rate (RGR) and net primary production (NPP) of ES and LS forest stands in an Afromontane tropical rainforest using data from inventories of quantitatively important ecosystem compartments in fifteen 0.5 ha plots in Nyungwe National Park in Rwanda. The total C stock was 35 % larger in LS compared to ES plots due to significantly larger above-ground biomass (AGB; 185 and 76 Mg C ha-1 in LS and ES plots), while the soil and root C stock (down to 45 cm depth in the mineral soil) did not significantly differ between the two successional stages (178 and 204 Mg C ha-1 in LS and ES plots). The main reasons for the difference in AGB were that ES trees had significantly lower stature and wood density compared to LS trees. However, ES and LS stands had similar total NPP (canopy, wood and roots of all plots ˜ 9.4 Mg C ha-1) due to counterbalancing effects of differences in AGB (higher in LS stands) and RGR (higher in ES stands). The AGB in the LS plots was considerably higher than the average value reported for old-growth tropical montane forest of south-east Asia and Central and South America at similar elevations and temperatures, and of the same magnitude as in tropical lowland forest of these regions. The results of this study highlight the importance of accounting for disturbance regimes and differences in wood density and allometry of tree species dominating at different successional stages in an attempt to quantify the C stock and sink strength of tropical montane forests and how they may differ among continents.

How High Frequency Trading Affects a Market Index

PubMed Central

Kenett, Dror Y.; Ben-Jacob, Eshel; Stanley, H. Eugene; gur-Gershgoren, Gitit

2013-01-01

The relationship between a market index and its constituent stocks is complicated. While an index is a weighted average of its constituent stocks, when the investigated time scale is one day or longer the index has been found to have a stronger effect on the stocks than vice versa. We explore how this interaction changes in short time scales using high frequency data. Using a correlation-based analysis approach, we find that in short time scales stocks have a stronger influence on the index. These findings have implications for high frequency trading and suggest that the price of an index should be published on shorter time scales, as close as possible to those of the actual transaction time scale. PMID:23817553

A fuzzy logic model to forecast stock market momentum in Indonesia's property and real estate sector

NASA Astrophysics Data System (ADS)

Penawar, H. K.; Rustam, Z.

2017-07-01

The Capital market has the important role in Indonesia's economy. The capital market does not only support the economy of Indonesia but also being an indicator Indonesia's economy improvement. Something that has been traded in the capital market is stock (stock market). Nowadays, the stock market is full of uncertainty. That uncertainty values make predicting stock market is all that we have to do before we make a decision in the stock market. One that can be predicted in the stock market is momentum. To forecast stock market momentum, it can use fuzzy logic model. In the process of modeling, it will be used 14 days historical data that consisting the value of open, high, low, and close, to predict the next 5 days momentum categories. There are three momentum categories namely Bullish, Neutral, and Bearish. To illustrate the fuzzy logic model, we will use stocks data from several companies that listed on Indonesia Stock Exchange (IDX) in property and real estate sector.

Identification and stocking density of elements phosphate indigo system for fish farming cages nets floating in freshwater district Laut Tawar, Aceh Province

NASA Astrophysics Data System (ADS)

Eriyusni, N.; Siregar, A. Z.

2018-02-01

Lake Laut Tawar is located in Aceh district of Aceh province. The lake were used by the community as a livelihood by making a Cages. One of the elements that influence the fish growth is an element Phosphate (PO4) and other such as, pH, nitrate-nitrite, temperature and others. The lake has undergone changes caused by the use of commercial feed. The sampling locations based on the environmental setting by using method "purposive sampling" from January to May. The results was found of 0.1407 mg/L phosphate with fish expenditure amounting to 23728.61 ton / year using cages of net with number as 92, stocking density at 48,950 of fish and marine area 19.77 Ha. However the standard classes showed is under class II Regulation with No. 82 Year 2001 3400, solid lowest stocking cages tail on the size of 2.5 x 2.5 x 3M (spacious, 181m3) with post-harvest fish expenditure amounted to 1,214 tons of fish/year, the highest 9,250 cages tail on the size e of 5 x 5 x 3m (spacious 123m3) with fish expenditure by 2,800 tones of fish/year. While the results of feed conversion and Phosphate content is 12.70% with the Feed Conversion Ratio (FCR) was 1,635 and 1,491.

Efficacy of moxidectin against cyathostomins after long-term use in a large herd of draught horses with a high stocking density.

PubMed

Schumacher, J; Livesey, L; DeGraves, F; Blagburn, B; Ziska, S; Caldwell, M; Brock, K

2009-05-23

This study was undertaken to determine whether resistance to moxidectin had developed in a large herd of draught horses, maintained on a small acreage, which had been routinely treated with moxidectin for five years. Faeces were collected for egg counts immediately before moxidectin gel was administered orally, and seven, 30, 60 and 90 days later. The faecal egg counts were significantly reduced at seven and 30 days after treatment, but were not significantly different from pretreatment counts at 60 and 90 days after treatment. There was no evidence of resistance having developed.

Improving Estimates of Acceptable Growiing Stock in Young Upland Oak Forests in the Missouri Ozarks

Treesearch

Daniel C. Dey; Paul S. Johnson; H.E. Garrett

1998-01-01

Estimates of regeneration or growing stock in young oak forests may be too high unless criteria are established that define explicitly acceptable growing stock. In young hardwood stands, crown class can be used to identify acceptable growing stock because it is related to the future growth and survival of reproduction. A method is presented for assigning crown class...

Survey of Foods to Improve Logistic Support and Extend Mission Endurance of Submarines

DTIC Science & Technology

1981-12-01

lower priority. For example, in the computer run, Chicken , Frozen, Broiler -Fryer, Whole (National Stock Number (NSN) 8905-00-126-3416) is specified...Increase ration density 1 (Decrease Logistical costs 2 Reduce number of line items 3 Conserve onboard refrigeration space 4 i Reduce food service labor...selection priority is based primarily on the ability of the substitute item to achieve increased ration density , and each subsequent I criterion has a

Nekton use of oyster occupied habitats in two coastal ponds in Rhode Island

EPA Science Inventory

Restoration of oyster habitat aims to expand or preserve ecosystem services including increased secondary production of the community. We compare density, biomass, and average standing stock of nitrogen and carbon in seasonal fish and invertebrate collections in Ninigret and Gree...

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

Meikle, T.; Ballek, L.; Briggs, B.

This study investigates the cost effectiveness of three separate reclamation methods utilized in the long-term establishment of Big Sage (Artemisia tridentata va. wyomingensis). Direct seeding and planting with four cubic inch and ten cubic inch containerized stock were compared using five 36 square meter plots per treatment within a fenced randomized block. Seed plots were hand broadcast at a rate of 2 kilograms per hectare and mulched with certified weed-free wheat straw. Containerized stock plots were planted at a density of one per square meter. Controls with no seeding or planting were established to differentiate actual plant production/reproduction from seedmore » bank recruitment and migration from replaced topsoil and surrounding native areas. Stem density (stem/m{sup 2}), plant height (cm), and plant reproduction (seedlings/m{sup 2}) data will be gathered every spring and fall for three years (1994-1997). Final analysis of the data will relate establishment success to cost efficiency. This initial report on the study reviews only seedling establishment based on first year data.« less

Real-Time Quantitative PCR Measurement of Ileal Lactobacillus salivarius Populations from Broiler Chickens To Determine the Influence of Farming Practices▿ †

PubMed Central

Harrow, Sally A.; Ravindran, Velmurugu; Butler, Ruth C.; Marshall, John W.; Tannock, Gerald W.

2007-01-01

A real-time quantitative PCR assay targeting a 16S-23S intergenic spacer region sequence was devised to measure the sizes of populations of Lactobacillus salivarius present in ileal digesta collected from broiler chickens. This species has been associated with deconjugation of bile salts in the small bowel and reduced broiler productivity. The assay was tested as a means of monitoring the sizes of L. salivarius populations from broilers fed diets with different compositions, maintained at different stocking densities, or given the antimicrobial drugs bacitracin and monensin in the feed. Stocking densities did not influence the numbers of L. salivarius cells in the ileum. A diet containing meat and bone meal reduced the size of the L. salivarius population relative to that of chickens given the control diet, as did administration of bacitracin and monensin in the feed. These changes in the target bacterial population were associated with improved broiler weight gain. PMID:17890342

The effect of low-density broiler breeder diets on performance and immune status of their offspring.

PubMed

Enting, H; Boersma, W J A; Cornelissen, J B W J; van Winden, S C L; Verstegen, M W A; van der Aar, P J

2007-02-01

Effects of low-density broiler breeder diets on offspring performance and mortality were studied using 2,100 female and 210 male Cobb 500 breeders. Breeder treatments involved 4 experimental groups and a control group with normal density diets (ND, 2,600 kcal of AME/kg during rearing and 2,800 kcal of AME/kg during laying). In treatment 2, nutrient densities were decreased by 12% (LD12) and 11% (LD11) during the rearing and laying periods, respectively, whereas in treatment 3, nutrient densities were decreased by 23% (LD23) and 21% (LD21) during the rearing and laying periods, respectively. The nutrient density in these treatments was decreased through inclusion of palm kernel meal, wheat bran, wheat gluten feed, and sunflower seed meal in the diets. Treatment 4 included diets with the same nutrient densities as in treatment 2 but included oats and sugar beet pulp (LD12(OP) and LD11(OP)). In treatment 5, the same low-density diet was given to the breeders as in treatment 2 during the rearing period, but it was followed by a normal density diet during the laying period (LD12-ND). Treatments were applied from 4 to 60 wk of age. On low-density diets, offspring showed an increased 1-d-old weight. As compared with offspring of breeders that received ND, the d 38 live weight of chickens from 29-wk-old breeders fed LD11 was improved. Mortality was reduced in offspring from 60-wk-old parent stock given low-density diets. The IgM titers in 35-d-old offspring from eggs with a lower-than-average weight were reduced when 29-wk-old broiler breeders were fed low-density diets. In offspring from eggs with a higher-than-average weight from 60-wk-old parent stock given LD11 or LD21 diets, IgM titers were higher compared with ND. It was concluded that low-density broiler breeder diets can improve offspring growth rates, reduce mortality, and reduce or increase immune responses, depending on breeder age and egg weight.

Recycling strategy of the end-of-life rolling stock in China

NASA Astrophysics Data System (ADS)

Guo, L.; Wang, X. W.; Lin, Y.; Shen, X. F.; Liu, Y. Q.

2018-03-01

China's high-speed railway industry is growing fast, the side effect is that plenty of rolling stock come to the end of life each year. However, there are not relevant standards nor regulations for the recycling of rolling stock in China, which causes pollution and a waste of resources. In this paper, the basic meaning and characteristics of the circular economy is reviewed and applied to the rolling stock industry. The recycling steps are elaborated in detail according to the characteristics of rolling stock. The result proves that circular economy has both the theoretical and practical meaning in the rolling stock recycling industry in China.

Soil Bulk Density by Soil Type, Land Use and Data Source: Putting the Error in SOC Estimates

NASA Astrophysics Data System (ADS)

Wills, S. A.; Rossi, A.; Loecke, T.; Ramcharan, A. M.; Roecker, S.; Mishra, U.; Waltman, S.; Nave, L. E.; Williams, C. O.; Beaudette, D.; Libohova, Z.; Vasilas, L.

2017-12-01

An important part of SOC stock and pool assessment is the assessment, estimation, and application of bulk density estimates. The concept of bulk density is relatively simple (the mass of soil in a given volume), the specifics Bulk density can be difficult to measure in soils due to logistical and methodological constraints. While many estimates of SOC pools use legacy data in their estimates, few concerted efforts have been made to assess the process used to convert laboratory carbon concentration measurements and bulk density collection into volumetrically based SOC estimates. The methodologies used are particularly sensitive in wetlands and organic soils with high amounts of carbon and very low bulk densities. We will present an analysis across four database measurements: NCSS - the National Cooperative Soil Survey Characterization dataset, RaCA - the Rapid Carbon Assessment sample dataset, NWCA - the National Wetland Condition Assessment, and ISCN - the International soil Carbon Network. The relationship between bulk density and soil organic carbon will be evaluated by dataset and land use/land cover information. Prediction methods (both regression and machine learning) will be compared and contrasted across datasets and available input information. The assessment and application of bulk density, including modeling, aggregation and error propagation will be evaluated. Finally, recommendations will be made about both the use of new data in soil survey products (such as SSURGO) and the use of that information as legacy data in SOC pool estimates.

Fire severity alters the distribution of pyrogenic carbon stocks across ecosystem pools in a Californian mixed-conifer forest

NASA Astrophysics Data System (ADS)

Maestrini, Bernardo; Alvey, Erin C.; Hurteau, Matthew D.; Safford, Hugh; Miesel, Jessica R.

2017-09-01

Pyrogenic carbon (PyC) is hypothesized to play an important role in the carbon (C) cycle due to its resistance to decomposition; however, much uncertainty still exists regarding the stocks of PyC that persist on-site after the initial erosion in postfire forests. Therefore, understanding how fire characteristics influence PyC stocks is vital, particularly in the context of California forests for which an increase of high-severity fires is predicted over the next decades. We measured forest C and persistent PyC stocks in areas burned by low-to-moderate and high-severity fire, as well as in adjacent unburned areas in a California mixed-conifer forest, 2 to 3 years after wildfire. We measured C and PyC stocks in the following compartments: standing trees, downed wood, forest floor, and mineral soil (0-5 cm), and we identified PyC using the weak nitric acid digestion method. We found that the total stock of PyC did not differ among fire severity classes (overall mean 248 ± 30 g C m-2); however, fire severity influenced the distribution of PyC in the individual compartments. Areas burned by high-severity fire had 2.5 times more PyC stocked in the coarse woody debris (p < 0.05), 3.3 times more PyC stocked in standing trees (p < 0.05), and a lower PyC stock in the forest floor (-22%, p < 0.05) compared to low-to-moderate fire severity areas. These results have important implications for the permanence time of PyC, which is putatively higher in standing trees and coarse woody debris compared to the forest floor, where it is susceptible to rapid losses through erosion.

Steelhead Supplementation in Idaho Rivers : 2001 Project Progress Report.

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

Byrne, Alan

In 2001, Idaho Department of Fish and Game (IDFG) continued an assessment of the Sawtooth Hatchery steelhead Oncorhynchus mykiss stock to reestablish natural populations in Beaver and Frenchman creeks in the upper Salmon River. Crews stocked both streams with 20 pair of hatchery adults, and I estimated the potential smolt production from the 2000 adult outplants. n the Red River drainage, IDFG stocked Dworshak hatchery stock fingerlings and smolts from 1993 to 1999 to assess which life stage produces more progeny when the adults return to spawn. In 2001, IDFG operated the Red River weir to trap adults that returnedmore » from these stockings, but none were caught from either group. Wild steelhead populations in the Lochsa and Selway river drainages were assessed and the chinook salmon Oncorhynchus tshawytscha escapement was enumerated in Fish Creek. I estimated that 75 wild adult steelhead and 122 adult chinook salmon returned to Fish Creek in 2001. I estimated that slightly more than 30,000 juvenile steelhead migrated out of Fish Creek. This is the largest number of steelhead to migrate out of Fish Creek in a single year since I began estimating the yearly migration in 1994. Juvenile steelhead densities in Lochsa and Selway tributaries were somewhat higher in 2001 than those observed in 2000. Crews from IDFG collected over 4,800 fin samples from wild steelhead in 74 streams of the Clearwater, Snake, and Salmon river drainages and from five hatchery stocks during the summer of 2000 for a DNA analysis to assess Idaho's steelhead stock structure. The DNA analysis was subcontracted to Dr. Jennifer Nielsen, Alaska Biological Science Center, Anchorage. Her lab developed protocols to use for the analysis in 2001 and is continuing to analyze the samples. Dr. Nielsen plans to have the complete set of wild and hatchery stocks analyzed in 2002.« less

Blue carbon stocks in Baltic Sea eelgrass (Zostera marina) meadows

NASA Astrophysics Data System (ADS)

Röhr, Maria Emilia; Boström, Christoffer; Canal-Vergés, Paula; Holmer, Marianne

2016-11-01

Although seagrasses cover only a minor fraction of the ocean seafloor, their carbon sink capacity accounts for nearly one-fifth of the total oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. We sampled 10 eelgrass (Zostera marina) meadows in Finland and 10 in Denmark to explore seagrass carbon stocks (Corg stock) and carbon accumulation rates (Corg accumulation) in the Baltic Sea area. The study sites represent a gradient from sheltered to exposed locations in both regions to reflect expected minimum and maximum stocks and accumulation. The Corg stock integrated over the top 25 cm of the sediment averaged 627 g C m-2 in Finland, while in Denmark the average Corg stock was over 6 times higher (4324 g C m-2). A conservative estimate of the total organic carbon pool in the regions ranged between 6.98 and 44.9 t C ha-1. Our results suggest that the Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Our analysis further showed that > 40 % of the variation in the Corg stocks was explained by sediment characteristics, i.e. dry density, porosity and silt content. In addition, our analysis show that the root : shoot ratio of Z. marina explained > 12 % and the contribution of Z. marina detritus to the sediment surface Corg pool explained > 10 % of the variation in the Corg stocks. The mean monetary value for the present carbon storage and carbon sink capacity of eelgrass meadows in Finland and Denmark, were 281 and 1809 EUR ha-1, respectively. For a more comprehensive picture of seagrass carbon storage capacity, we conclude that future blue carbon studies should, in a more integrative way, investigate the interactions between sediment biogeochemistry, seascape structure, plant species architecture and the hydrodynamic regime.

Steelhead Supplementation Studies; Steelhead Supplementation in Idaho Rivers, Annual Report 2002.

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

Byrne, Alan

The Steelhead Supplementation Study (SSS) has two broad objectives: (1) investigate the feasibility of supplementing depressed wild and natural steelhead populations using hatchery populations, and (2) describe the basic life history and genetic characteristics of wild and natural steelhead populations in the Salmon and Clearwater Basins. Idaho Department of Fish and Game (IDFG) personnel stocked adult steelhead from Sawtooth Fish Hatchery into Frenchman and Beaver creeks and estimated the number of age-1 parr produced from the outplants since 1993. On May 2, 2002, both Beaver and Frenchman creeks were stocked with hatchery adult steelhead. A SSS crew snorkeled the creeksmore » in August 2002 to estimate the abundance of age-1 parr from brood year (BY) 2001. I estimated that the yield of age-1 parr per female stocked in 2001 was 7.3 and 6.7 in Beaver and Frenchman creeks, respectively. SSS crews stocked Dworshak hatchery stock fingerlings and smolts from 1993 to 1999 in the Red River drainage to assess which life stage produces more progeny when the adults return to spawn. In 2002, Clearwater Fish Hatchery personnel operated the Red River weir to trap adults that returned from these stockings. Twelve PIT-tagged adults from the smolt releases and one PIT-tagged adult from fingerling releases were detected during their migration up the mainstem Columbia and Snake rivers, but none from either group were caught at the weir. The primary focus of the study has been monitoring and collecting life history information from wild steelhead populations. An adult weir has been operated annually since 1992 in Fish Creek, a tributary of the Lochsa River. The weir was damaged by a rain-on-snow event in April 2002 and although the weir remained intact, some adults were able to swim undetected through the weir. Despite damage to the weir, trap tenders captured 167 adult steelhead, the most fish since 1993. The maximum likelihood estimate of adult steelhead escapement was 242. A screw trap has been operated annually in Fish Creek since 1994 to estimate the number of emigrating parr and smolts. I estimated that 18,687 juvenile steelhead emigrated from Fish Creek in 2002, the lowest number of migrants since 1998. SSS crews snorkeled three streams in the Selway River drainage and 10 streams in the Lochsa River drainage to estimate juvenile steelhead densities. The densities of age-1 steelhead parr declined in all streams compared to the densities observed in 2001. The age-1 densities in Fish Creek and Gedney Creek were the lowest observed since this project began monitoring those populations in 1994. The SSS crews and other cooperators tagged more than 12,000 juvenile steelhead with passive integrated transponder (PIT) tags in 2002. In 2002, technicians mounted and aged steelhead scales that were collected from 1998 to 2001. A consensus was reached among technicians for age of steelhead juveniles from Fish Creek. Scales that were collected in other streams were aged by at least one reader; however, before a final age is assigned to these fish, the age needs to be verified by another reader and any age differences among readers resolved. Dr. Jennifer Nielsen, at the U.S. Geological Survey Alaska Biological Science Center, Anchorage continued the microsatellite analysis of the steelhead tissue samples that were collected from Idaho streams in 2000. Two thousand eighteen samples from 40 populations were analyzed. The analysis of the remaining 39 populations is continuing.« less

Carbon Storage in US Wetlands. | Science Inventory | US EPA

EPA Pesticide Factsheets

Background/Question/Methods Wetland soils contain some of the highest stores of soil carbon in the biosphere. However, there is little understanding of the quantity and distribution of carbon stored in US wetlands or of the potential effects of human disturbance on these stocks. We provide unbiased estimates of soil carbon stocks for wetlands at regional and national scales and describe how soil carbon stocks vary by anthropogenic disturbance to the wetland. To estimate the quantity and distribution of carbon stocks in wetlands of the conterminous US, we used data gathered in the field as part of the 2011 National Wetland Condition Assessment (NWCA) conducted by USEPA. During the growing season, field crews collected soil samples by horizon from 120-cm deep soil pits at 967 randomly selected wetland sites. Soil samples were analyzed for bulk density and organic carbon. We applied site carbon stock averages by soil depth back to the national population of wetlands and to several subpopulations, including five geographic areas and anthropogenic disturbance level. Disturbance levels were categorized by the NWCA as least, intermediately, or most disturbed using a priori defined physical, chemical, and biological indicators that were observable at the time of the site visit.Results/Conclusions We find that wetlands in the conterminous US store a total of 11.52 PgC – roughly equivalent to four years of annual carbon emissions by the US, with the greatest soil ca

Monosodium glutamate in chicken and beef stock cubes using high-performance liquid chromatography.

PubMed

Demirhan, Buket Er; Demirhan, Burak; Sönmez, Ceren; Torul, Hilal; Tamer, Uğur; Yentür, Gülderen

2015-01-01

In this survey monosodium glutamate (MSG) levels in chicken and beef stock cube samples were determined. A total number of 122 stock cube samples (from brands A, B, C, D) were collected from local markets in Ankara, Turkey. High-performance liquid chromatography with diode array detection (HPLC-DAD) was used for quantitative MSG determination. Mean MSG levels (±SE) in samples of A, B, C and D brands were 14.6 ± 0.2 g kg⁻¹, 11.9 ± 0.3 g kg⁻¹, 9.7 ± 0.1 g kg⁻¹ and 7.2 ± 0.1 g kg⁻¹, respectively. Differences between mean levels of brands were significant. Also, mean levels of chicken stock cube samples were lower than in beef stock cubes. Maximum limits for MSG in stock cubes are not specified in the Turkish Food Codex (TFC). Generally the limit for MSG in foods (except some foods) is established as 10 g kg⁻¹ (individually or in combination).

Size asymmetry in intraspecific competition and the density-dependence of inbreeding depression in a natural plant population: a case study in cassava (Manihot esculenta Crantz, Euphorbiaceae).

PubMed

Pujol, B; McKey, D

2006-01-01

The effects of competition on the genetic composition of natural populations are not well understood. We combined demography and molecular genetics to study how intraspecific competition affects microevolution in cohorts of volunteer plants of cassava (Manihot esculenta) originating from seeds in slash-and-burn fields of Palikur Amerindians in French Guiana. In this clonally propagated crop, genotypic diversity is enhanced by the incorporation of volunteer plants into farmers' stocks of clonal propagules. Mortality of volunteer plants was density-dependent. Furthermore, the size asymmetry of intraspecific competition increased with local clustering of plants. Size of plants was correlated with their multilocus heterozygosity, and stronger size-dependence of survival in clusters of plants, compared with solitary plants, increased the magnitude of inbreeding depression when competition was severe. The density-dependence of inbreeding depression of volunteer plants helps explain the high heterozygosity of volunteers that survive to harvest time and thus become candidates for clonal propagation. This effect could help favour the maintenance of sex in this 'vegetatively' propagated crop plant.

Soil organic matter stabilization in grazing highland soils from the Andean Plateau

NASA Astrophysics Data System (ADS)

Muñoz, M. A.; Faz, A.; Zornoza, R.

2012-04-01

Grasslands comprise approximately 40% of the earth's land area and play a critical role in the global carbon cycle. Apolobamba is a grazing highland located in the Andean Plateau where sustainable vicuna (Vicugna vicugna) management programme is carried out. Understanding the soil properties and the organic matter dynamics is fundamental to determine the grazing impacts in the carbon reservoirs. However, the labile and recalcitrant fractions of C have not been widely studied under field conditions, especially in high grasslands. The objectives of this survey were to: (i) achieve a soil characterization through general physico-chemical properties and (ii) study soil organic matter stabilization through recalcitrant and labile carbon budgets in Apolobamba. Regarding the lastly vicuna censuses carried out in the studied area, eight representative zones with different vicuna densities were selected and soil samples were collected. Other characteristics were also considered to select the study zones: (1) alpaca densities, (2) vegetation communities (3) plant cover and (4) landscape and geo-morphological description. Recalcitrant and water soluble organic carbon were determined as well as recalcitrant index. General soil characterization showed strongly acid and no saline soils with high cation exchange capacity and sandy-loam and loam textures. Total nitrogen contents indicated no limitation for the native vegetation growth. In general, no relationships were found among general soil properties, vicuna and alpaca densities; however, zones with highest alpaca density could be prone to soil erosion based on the available P distribution and the texture results. Additionally, a negative alpaca grazing influence in the soil organic carbon stocks was observed. On the other hand, high soil recalcitrant carbon contents (3.7 ± 0.3 kg m-2) and recalcitrance index (0.8 ± 0.1) were found. Likewise, labile C exhibited similar values to those obtained from researchers conducted in grasslands. These observations could be positive aspects in the preservation or stabilization of the soil mineral particles and the long term carbon sequestration. We suggest that the soil C stabilization mechanisms in mountain grassland may be affected by the lower temperatures and acid soil pH. In conclusion, Apolobamba could have a significant reservoir of stabilized soil organic matter. However, there is an urgent need to establish soil protection strategies against the alpaca overexploitation in order to protect the organic matter stocks and to continue with the vicuna sustainable management in the Andean Plateau. Keywords: carbon reservoirs, highland soils, recalcitrant carbon, vicuna

Fire recurrence effects on aboveground plant and soil carbon stocks in Mediterranean shrublands with Aleppo pine

NASA Astrophysics Data System (ADS)

Herman, J.; den Ouden, J.; Mohren, G. M. J.; Retana, J.; Serrasolses, I.

2009-04-01

Changes in fire regime due to intensification of human influence during the last decades led to changes in vegetation structure and composition, productivity and carbon sink strength of Mediterranean shrublands and forests. It is anticipated that further climate warming and lower precipitation will enhance fire frequency, having consequences for the carbon budget and carbon storage in Mediterranean ecosystems. The purpose of this study was to determine whether fire recurrence modifies aboveground plant and soil carbon stocks, soil organic carbon content and total soil nitrogen content in shrublands with Aleppo pine on the Garraf Massif in Catalonia (Spain). Stands differing in fire frequency (1, 2 and 3 fires since 1957) were examined 13 years after the stand-replacing fire of 1994 and compared with control stands which were free of fire since 1957. Recurrent fires led to a decrease in total ecosystem carbon stocks. Control sites stored 12203 g m-2C which was 3.5, 5.0 and 5.5 times more than sites that burned 1, 2 and 3 times respectively. Carbon stored in the aboveground biomass exceeded soil carbon stocks in control plots, while soils were the dominant carbon pool in burned plots. An increasing fire frequency from 1 to 2 fires decreased total soil carbon stock. Control soils stored 3551 g m-2C, of which 70 % was recovered over 13 years in once burned soils and approximately 50 % in soils that had 2 or 3 fires. The soil litter (LF) layer carbon stock decreased with increasing fire frequency from 1 to 2 fires, whereas humus (H) layer and upper mineral soil carbon stocks did not change consistently with fire frequency. Fire decreased the organic carbon content in LF and H horizons, however no significant effect of fire frequency was found. Increasing fire frequency from 1 to 2 fires caused a decrease in the organic carbon content in the upper mineral soil. Total soil N content and C/N ratios were not significantly impacted by fire frequency. Recurrent fires had the greatest impact on aboveground plant carbon stocks. Aboveground plants in control plots amounted to 8652 g m-2C, of which 93 % was stored in trees, while carbon storage in the most frequently burned sites was only 509 g m-2C. Shrub carbon varied barely between fire frequencies, corroborating the high resilience of resprouting shrub species to fire recurrence. The most striking result was the immense decrease in Aleppo pine carbon stock which varied between 7770 g m-2in control plots and 25.6 g m-2in 3-fires plots. Differences between control and burned plots are principally explained by the age of the plots. The decrease in Aleppo pine carbon stock within burned plots was not associated with a growth reduction, but was due to a decrease in stem density. The results indeed indicate that the recruitment of Aleppo pine on more frequently burned plots is obstructed due to cumulative effects of short fire return-intervals (

Identifying Key Drivers of Return Reversal with Dynamical Bayesian Factor Graph

PubMed Central

Zhao, Shuai; Tong, Yunhai; Wang, Zitian; Tan, Shaohua

2016-01-01

In the stock market, return reversal occurs when investors sell overbought stocks and buy oversold stocks, reversing the stocks’ price trends. In this paper, we develop a new method to identify key drivers of return reversal by incorporating a comprehensive set of factors derived from different economic theories into one unified dynamical Bayesian factor graph. We then use the model to depict factor relationships and their dynamics, from which we make some interesting discoveries about the mechanism behind return reversals. Through extensive experiments on the US stock market, we conclude that among the various factors, the liquidity factors consistently emerge as key drivers of return reversal, which is in support of the theory of liquidity effect. Specifically, we find that stocks with high turnover rates or high Amihud illiquidity measures have a greater probability of experiencing return reversals. Apart from the consistent drivers, we find other drivers of return reversal that generally change from year to year, and they serve as important characteristics for evaluating the trends of stock returns. Besides, we also identify some seldom discussed yet enlightening inter-factor relationships, one of which shows that stocks in Finance and Insurance industry are more likely to have high Amihud illiquidity measures in comparison with those in other industries. These conclusions are robust for return reversals under different thresholds. PMID:27893780

Mob grazing for dairy cows

USDA-ARS?s Scientific Manuscript database

Proponents of mob grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 lb/ac of beef cattle on small paddocks with rest periods up to 125 days. However, it is unclear if this management technique is appropriate for dair...

Hybrid Clustering-GWO-NARX neural network technique in predicting stock price

NASA Astrophysics Data System (ADS)

Das, Debashish; Safa Sadiq, Ali; Mirjalili, Seyedali; Noraziah, A.

2017-09-01

Prediction of stock price is one of the most challenging tasks due to nonlinear nature of the stock data. Though numerous attempts have been made to predict the stock price by applying various techniques, yet the predicted price is not always accurate and even the error rate is high to some extent. Consequently, this paper endeavours to determine an efficient stock prediction strategy by implementing a combinatorial method of Grey Wolf Optimizer (GWO), Clustering and Non Linear Autoregressive Exogenous (NARX) Technique. The study uses stock data from prominent stock market i.e. New York Stock Exchange (NYSE), NASDAQ and emerging stock market i.e. Malaysian Stock Market (Bursa Malaysia), Dhaka Stock Exchange (DSE). It applies K-means clustering algorithm to determine the most promising cluster, then MGWO is used to determine the classification rate and finally the stock price is predicted by applying NARX neural network algorithm. The prediction performance gained through experimentation is compared and assessed to guide the investors in making investment decision. The result through this technique is indeed promising as it has shown almost precise prediction and improved error rate. We have applied the hybrid Clustering-GWO-NARX neural network technique in predicting stock price. We intend to work with the effect of various factors in stock price movement and selection of parameters. We will further investigate the influence of company news either positive or negative in stock price movement. We would be also interested to predict the Stock indices.

Economic efficiency of high-rise construction in the Moscow program of renovation of housing stock

NASA Astrophysics Data System (ADS)

Misailovov, Andrey

2018-03-01

The article considers a new initiative of the regional authorities of updating the housing stock designated as the renovation of housing. Its main aspects are analyzed, including the nature of program, economic efficiency of its implementation due to high-rise construction and the regulatory and legislative framework, the procedure for implementing the program, and the time frame for its implementation. The role of the program for regions in which high depreciation of the housing stock is combined with a limited number of sites for a new housing construction is disclosed. The high-rise construction in the renovation program is presented as a variant of a successful solution not only of the tasks of renovating the housing stock, but also of filling the regional budget. The social and economic orientation of the high-rise construction and the involvement of residents in the process of making town-planning decisions in the field of high-rise construction at all stages of implementing the program are shown.

Historic changes in length distributions of three Baltic cod (Gadus morhua) stocks: Evidence of growth retardation.

PubMed

Svedäng, Henrik; Hornborg, Sara

2017-08-01

Understanding how combinations of fishing effort and selectivity affect productivity is central to fisheries research. We investigate the roles of fishing regulation in comparison with ecosystem status for Baltic Sea cod stock productivity, growth performance, and population stability. This case study is interesting because three cod populations with different exploitation patterns and stock status are located in three adjacent but partially, ecologically different areas. In assessing stock status, growth, and productivity, we use survey information and rather basic stock parameters without relying on age readings. Because there is an urgent interest of better understanding of the current development of the Eastern Baltic cod stock, we argue that our approach represents partly a novel way of interpreting monitoring information together with catch data in a simplified yet more informative way. Our study reports how the Eastern and Western Baltic cod have gone toward more truncated size structures between 1991 and 2016, in particular for the Eastern Baltic cod, whereas the Öresund cod show no trend. We suggest that selective fishing may disrupt fish population dynamic stability and that lower natural productivity might amplify the effects of selective fishing. In support of earlier findings on a density-dependent growth of Eastern Baltic cod, management is advised to acknowledge that sustainable exploitation levels for Eastern Baltic cod are much more limited than perceived in regular assessments. Of more general importance, our results emphasize the need to embrace a more realistic view on what ecosystems can produce regarding tractable fish biomass to facilitate a more ecosystem-based fisheries management.

Financial factor influence on scaling and memory of trading volume in stock market

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Fengzhong; Havlin, Shlomo; Stanley, H. Eugene

2011-10-01

We study the daily trading volume volatility of 17 197 stocks in the US stock markets during the period 1989-2008 and analyze the time return intervals τ between volume volatilities above a given threshold q. For different thresholds q, the probability density function Pq(τ) scales with mean interval <τ> as Pq(τ)=<τ>-1f(τ/<τ>), and the tails of the scaling function can be well approximated by a power law f(x)˜x-γ. We also study the relation between the form of the distribution function Pq(τ) and several financial factors: stock lifetime, market capitalization, volume, and trading value. We find a systematic tendency of Pq(τ) associated with these factors, suggesting a multiscaling feature in the volume return intervals. We analyze the conditional probability Pq(τ|τ0) for τ following a certain interval τ0, and find that Pq(τ|τ0) depends on τ0 such that immediately following a short (long) return interval a second short (long) return interval tends to occur. We also find indications that there is a long-term correlation in the daily volume volatility. We compare our results to those found earlier for price volatility.

The Interactive Influence of Perceived Ownership and Perceived Choosership of Stocks on Brain Response to Stock Outcomes

PubMed Central

Shang, Zhe; Wang, Lei; Wu, Han

2017-01-01

The present research examined the influence of perceived ownership (self/other) and perceived chooser (self/other) of stocks on brain activity, and investigated whether differential brain responses to stock outcomes as a result of perceived differences in ownership of stock would be modulated by perceived chooser of stock. We used a 2 (stock chooser: self, other) × 2 (stock owner: self, other) within-subject design to represent four types of chooser-owner relationships. Brain potentials were recorded while participants observed increasing and decreasing stock prices. Results showed that observations of stock outcomes among four types of chooser-owner relationships elicited differentiated feedback-related negativity (d-FRN: differences in FRN waves between losses and gains, reflecting violations of expectancy to stock outcomes): (1) Self-chosen-other-owned stocks evoked significantly larger d-FRN discrepancies than self-chosen-self-owned stocks, indicating a greater expectancy violation to others' losses than to one's own, demonstrating a reversed ownership effect. Moreover, people high in conscientiousness showed an increase in this trend, suggesting a stronger other-consideration; (2) Self-chosen-self-owned stocks and other-chosen-self-owned stocks revealed no significant d-FRN discrepancy, showing no choosership effect beyond the ownership effect; (3) Other-chosen-self-owned stocks evoked a significantly stronger d-FRN discrepancy than other-chosen-other-owned stocks, demonstrating an ownership effect; (4) Self-chosen-other-owned stocks evoked a significantly stronger d-FRN discrepancy than other-chosen-other-owned stocks, revealing a choosership effect. These findings suggest that the ownership effect could be reversed by conscientiousness induced by perceived choosership in the agency relationship, while the choosership effect is attenuated and even disappears under the influence of perceived ownership. PMID:28194118

A modern soil carbon stock baseline for the conterminous United States

NASA Astrophysics Data System (ADS)

Loecke, T.; Wills, S. A.; Teachman, G.; Sequeira, C.; West, L.; Wijewardane, N.; Ge, Y.

2016-12-01

The Rapid Carbon Assessment Project was undertaken to ascertain the soil carbon stocks across the conterminous US at one point in time. Sample locations were chosen randomly from the NRI (National Resource Inventory) sampling framework and cover all areas in CONUS with SSURGO certified maps as of Dec 2010. The project was regionalized into 17 areas for logistical reasons. Within each region, soils were grouped by official series description properties. Sites were selected by soil groups and land use/cover as indicated by NRI or NLCD (USGS National Land Cover Dataset) class so that more extensive soils groups and/or land use/covers received more points and less extensive fewer points (with a minimum of 5 sites). Each region had 375 - 400 sites, for a total of approximately 6,400 sites. At each site, basic information about land use, vegetation and management were collected as appropriate and available. Samples were collected from 5 pedons (a central and 4 satellites) per site to a depth of 1m, at 0 - 5cm and by genetic horizon. A volumetric sample was collected for horizons above 50 cm to determine bulk density. For horizons below 50cm (or when a volumetric sample could not be obtained) bulk density was modeled from morphological information. All samples were air dried and crushed to <2mm. The central pedon was analyzed for total and organic carbon at the Kellogg Soil Science Laboratory in Lincoln, NE. A visible near-infrared (VNIR) spectrophotometer was used to predict organic and inorganic carbon contents for all satellites samples. A Hierarchical Bayesian statistical approach was used to estimate C stocks, concentrations, and uncertainty for each sampling level (i.e., CONUS, region, soil group, landuse and site). Carbon concentration and stocks were summarized by surface horizon and depth increments for sites, soil groups, and land use/groups and mapped by linking the values to a raster of SSURGO (Jan 2012) that includes map unit and NLCD classification. This modern soil C stock baseline data set will be useful for many application in climate science and biogeochemistry.

Availability, usage and expected contribution of potential nursery habitats for the California halibut

NASA Astrophysics Data System (ADS)

Fodrie, F. Joel; Mendoza, Guillermo

2006-06-01

Coastal ecosystems have been identified as important nursery habitats for many of the world's fishery species. Beyond this, there remain many questions about what exactly constitutes high-value, even critical, habitat for juvenile fish. A first step in investigating nursery habitat value should be to catalogue the spatial coverage (availability) of all potential nursery habitats as well as the distribution (usage) of juvenile fish within those habitats. We conducted two years of fall surveys in the nearshore areas of San Diego County, CA, examining the spatial distribution of 0-group California halibut, Paralichthys californicus. The database generated by 527 otter trawls and block-net seine collections was used to produce a series of models employing regression trees to study the abiotic factors (water column and bottom features) that affect juvenile distributions. Along the exposed coast, highest 0-group densities (0.002-0.008 individuals/m 2 (indiv/m 2)) occurred where temperatures exceeded 21.5 °C (2003), and at depths between 3.3 and 5.2 m (2004). Within protected embayments, densities were higher at depths less than 1.5 m (0.054-0.430 indiv/m 2) and, in 2004, inside channeled marsh estuaries (0.156 indiv/m 2). The spatial coverage of potential nursery habitats was calculated using a Geographic Information System (GIS) database, and the total number of resident 0-group halibut within each site was estimated (habitat area × juvenile halibut density) as a proxy for expected contribution of halibut advancing to the adult stock from each nursery. Although 85% of the potential nursery habitat area occurred along the exposed coastline, 69% (2003) to 58% (2004) of 0-group halibut resided in protected embayments. Embayment contribution is much greater in the southern half of the study region, largely due to Mission and San Diego bays. We conclude that all nursery habitat types demonstrate the potential to contribute significantly to stock fitness, and that in general, shallow and better-protected habitats are highly utilized nurseries for 0-group halibut and deserve special attention in management or conservation efforts.

Tree height and tropical forest biomass estimation

Treesearch

M.O. Hunter; M. Keller; D. Vitoria; D.C. Morton

2013-01-01

Tropical forests account for approximately half of above-ground carbon stored in global vegetation. However, uncertainties in tropical forest carbon stocks remain high because it is costly and laborious to quantify standing carbon stocks. Carbon stocks of tropical forests are determined using allometric relations between tree stem diameter and height and biomass....

Weibo sentiments and stock return: A time-frequency view

PubMed Central

Liu, Zhixin; Zhao, Jichang; Su, Chiwei

2017-01-01

This study provides new insights into the relationships between social media sentiments and the stock market in China. Based on machine learning, we classify microblogs posted on Sina Weibo, a Twitter’s variant in China into five detailed sentiments of anger, disgust, fear, joy, and sadness. Using wavelet analysis, we find close positive linkages between sentiments and the stock return, which have both frequency and time-varying features. Five detailed sentiments are positively related to the stock return for certain periods, particularly since October 2014 at medium to high frequencies of less than ten trading days, when the stock return is undergoing significant fluctuations. Sadness appears to have a closer relationship with the stock return than the other four sentiments. As to the lead-lag relationships, the stock return causes Weibo sentiments rather than reverse for most of the periods with significant linkages. Compared with polarity sentiments (negative vs. positive), detailed sentiments provide more information regarding relationships between Weibo sentiments and the stock market. The stock market exerts positive effects on bullishness and agreement of microblogs. Meanwhile, agreement leads the stock return in-phase at the frequency of approximately 40 trading days, indicating that less disagreement improves certainty about the stock market. PMID:28672026

Weibo sentiments and stock return: A time-frequency view.

PubMed

Xu, Yingying; Liu, Zhixin; Zhao, Jichang; Su, Chiwei

2017-01-01

This study provides new insights into the relationships between social media sentiments and the stock market in China. Based on machine learning, we classify microblogs posted on Sina Weibo, a Twitter's variant in China into five detailed sentiments of anger, disgust, fear, joy, and sadness. Using wavelet analysis, we find close positive linkages between sentiments and the stock return, which have both frequency and time-varying features. Five detailed sentiments are positively related to the stock return for certain periods, particularly since October 2014 at medium to high frequencies of less than ten trading days, when the stock return is undergoing significant fluctuations. Sadness appears to have a closer relationship with the stock return than the other four sentiments. As to the lead-lag relationships, the stock return causes Weibo sentiments rather than reverse for most of the periods with significant linkages. Compared with polarity sentiments (negative vs. positive), detailed sentiments provide more information regarding relationships between Weibo sentiments and the stock market. The stock market exerts positive effects on bullishness and agreement of microblogs. Meanwhile, agreement leads the stock return in-phase at the frequency of approximately 40 trading days, indicating that less disagreement improves certainty about the stock market.

Fish community changes in the St. Louis River estuary, Lake Superior, 1989-1996: Is it ruffe or population dynamics?

USGS Publications Warehouse

Bronte, Charles R.; Evrard, Lori M.; Brown, William P.; Mayo, Kathleen R.; Edwards, Andrew J.

1998-01-01

Ruffe (Gymnocephalus cernuus) have been implicated in density declines of native species through egg predation and competition for food in some European waters where they were introduced. Density estimates for ruffe and principal native fishes in the St. Louis River estuary (western Lake Superior) were developed for 1989 to 1996 to measure changes in the fish community in response to an unintentional introduction of ruffe. During the study, ruffe density increased and the densities of several native species decreased. The reductions of native stocks to the natural population dynamics of the same species from Chequamegon Bay, Lake Superior (an area with very few ruffe) were developed, where there was a 24-year record of density. Using these data, short- and long-term variations in catch and correlations among species within years were compared, and species-specific distributions were developed of observed trends in abundance of native fishes in Chequamegon Bay indexed by the slopes of densities across years. From these distributions and our observed trend-line slopes from the St. Louis River, probabilities of measuring negative change at the magnitude observed in the St. Louis River were estimated. Compared with trends in Chequamegon Bay, there was a high probability of obtaining the negative slopes measured for most species, which suggests natural population dynamics could explain, the declines rather than interactions with ruffe. Variable recruitment, which was not related to ruffe density, and associated density-dependent changes in mortality likely were responsible for density declines of native species.

Efficacy of a live attenuated Edwardsiella ictaluri oral vaccine in channel and hybrid catfish

USDA-ARS?s Scientific Manuscript database

Intensive fish production systems resort to higher stocking densities and feeding rates in culture conditions to manifest suboptimal conditions to facilitate disease outbreaks leading to production losses. This study was conducted to evaluate the efficacy of an oral live-attenuated Edwardsiella ict...

Biomass and nutrient mass of Acacia dealbata and Eucalyptus globulus bioenergy plantations

Treesearch

Timothy J. Albaugh; Rafael A. Rubilar; Chris A. Maier; Eduardo A. Acuña; Rachel L. Cook

2017-01-01

We quantified biomass and nutrient accumulation of Acacia dealbata Link and Eucalyptus globulus Labill. planted at stem densities of 5000 and 15000 ha-1 in a bioenergy plantation in Chile. We tested the hypotheses that species and stocking will not affect biomass or nutrient accumulation. Species and...

An integrated material metabolism model for stocks of urban road system in Beijing, China.

PubMed

Guo, Zhen; Hu, Dan; Zhang, Fuhua; Huang, Guolong; Xiao, Qiang

2014-02-01

Rapid urbanization has greatly altered the urban metabolism of material and energy. As a significant part of the infrastructure, urban roads are being rapidly developed worldwide. Quantitative analysis of metabolic processes on urban road systems, especially the scale, composition and spatial distribution of their stocks, could help to assess the resource appropriation and potential environmental impacts, as well as improve urban metabolism models. In this paper, an integrated model, which covered all types of roads, intersection structures and ancillary facilities, was built for calculating the material stocks of urban road systems. Based on a bottom-up method, the total stocks were disassembled into a number of stock parts rather than obtained by input-output data, which provided an approach promoting data availability and inner structure understanding. The combination with GIS enabled the model to tackle the complex structures of road networks and avoid double counting. In the case study of Beijing, the following results are shown: 1) The total stocks for the entire road system reached 159 million tons, of which nearly 80% was stored in roads, and 20% in ancillary facilities. 2) Macadam was the largest stock (111 million tons), while stone mastic asphalt, polyurethane plastics, and atactic polypropylene accounted for smaller components of the overall system. 3) The stock per unit area of pedestrian overcrossing was higher than that of the other stock units in the entire system, and its steel stocks reached 0.49 t/m(2), which was 10 times as high as that in interchanges. 4) The high stock areas were mainly distributed in ring-shaped and radial expressways, as well as in major interchanges. 5) Expressways and arterials were excessively emphasized, while minor roads were relatively ignored. However, the variation of cross-sectional thickness in branches and neighborhood roads will have a significant impact on the scale of material stocks in the entire road system. © 2013.

Kokanee Stocking and Monitoring, Flathead Lake, 1993-1994 Annual Report.

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

Deleray, Mark; Fredenberg, Wade; Hansen, Barry

1995-07-01

One mitigation goal of the Hungry Horse Dam fisheries mitigation program, funded by the Bonneville Power Administration, is to replace lost production of 100,000 adult kokanee in Flathead Lake. The mitigation program calls for a five-year test to determine if kokanee can be reestablished in Flathead Lake. The test consists. of annual stocking of one million hatchery-raised yearling kokanee. There are three benchmarks for judging the success of the kokanee reintroduction effort: (1) Post-stocking survival of 30 percent of planted kokanee one year after stocking; (2) Yearling to adult survival of 10 percent (100,000 adult salmon); (3) Annual kokanee harvestmore » of 50,000 or more fish per year by 1998, with an average length of 11 inches or longer for harvested fish, and fishing pressure of 100,000 angler hours or more. Kokanee were the primary sport fish species in the Flathead Lake fishery in the early 1900s, and up until the late 1980s when the population rapidly declined in numbers and then disappeared. Factors identified which influenced the decline of kokanee are the introduction of opossum shrimp (Mysis relicta), hydroelectric operations, overharvest through angling, and competition and/or predation by lake trout (Salvelinus namaycush) and lake whitefish (Coregonur clupeaformis). The purpose of this report was to summarize the stocking program and present monitoring results from the 1993 and 1994 field seasons. In June 1993, roughly 210,000 yearling kokanee were stocked into two bays on the east shore of Flathead Lake. Following stocking, we observed a high incidence of stocked kokanee in stomach samples from lake trout captured in areas adjacent to the stocking sites and a high percentage of captured lake trout containing kokanee. Subsequent monitoring concluded that excessive lake trout predation precluded significant survival of kokanee stocked in 1993. In June 1994, over 802,000 kokanee were stocked into Big Arm Bay. The combination of near optimum water temperatures, an upsurge in the abundance of Duphniu rhorum, and saturation planting in an area believed to have lower lake trout densities was expected to maximize short-term survival of stocked kokanee. A net-pen experiment demonstrated that yearling hatchery kokanee, in the absence of predation, adjusted to conditions in Flathead Lake and utilized available zooplankton during June and July without substantial poststocking mortality. Kokanee captured after several months in the lake exhibited good growth and condition. We concluded that the food supply in Big Arm Bay was not limiting survival of stocked kokanee. The 1994 monitoring objective was to quantify lake trout predation of kokanee in Big Arm Bay in the first eight weeks following stocking. There were three components needed to quantify predation; estimated number of lake trout in Big Arm Bay, average number of kokanee consumed by lake trout, and estimated time required for lake trout to digest kokanee. As in the previous year, the monitoring results from the 1994 kokanee plant demonstrated that lake trout predation is the primary factor reducing survival of stocked kokanee. We estimated that lake trout consumed a minimum of 232,000 kokanee in Big Arm Bay during the first eight weeks following stocking. This represents 29 percent of kokanee planted. The consumption estimate was based on a hydroacoustic estimate for lake trout abundance (7,850 fish over 300 mm in total length), an incidence of kokanee per lake trout stomach sample which ranged from 2.99 to 0.22 fish, and a gastric evacuation rate of 47 hours for lake trout to digest consumed kokanee. Due to hydroacoustic limitations in identifying bottom-oriented lake trout, we underestimated the true abundance of lake trout, which led to an underestimate of kokanee mortality. By fall of 1994, we estimated that an additional 12.7 percent of surviving kokanee matured, based on observations of similar-sized fish in the hatchery. Thus, up to 72,000 additional fish were removed from the population due to early maturation. Adding the loss due to predation in the first eight weeks (232,000) to the loss due to early maturation (72,000), we accounted for mortality of at least 304,000 (38 percent) of the original 802,000 fish planted. These estimates did not account for additional losses, including predation outside Big Arm Bay, predation in the months following July, and predation from species other than lake trout, such as bull trout and northern squawfish. We documented lake trout predation of kokanee from June through October, and predation by fish species other than lake trout. One of the program goals is to achieve post-stocking survival of 30 percent one year after planting. Based on observations of the 1994 program, it is unlikely we will achieve this level of survival from the 1994 plant.« less

Agricultural restructuring and gastrointestinal parasitism in domestic ruminants on the rangelands of Kazakhstan.

PubMed

Morgan, E R; Torgerson, P R; Shaikenov, B S; Usenbayev, A E; Moore, A B M; Medley, G F; Milner-Gulland, E J

2006-06-30

In order to evaluate the epidemiology of parasitism in farmed ruminants in the changed agricultural context in Kazakhstan, 505 cattle, sheep and goats were surveyed for gastrointestinal parasitism using coprological examination, and a further thirty sheep and four goats using post mortem extraction of helminths. The dominant helminth genera were Marshallagia, Nematodirus and Trichostrongylus. Haemonchus was also present. Faecal egg counts were low (mean abundance 0-115 eggs per gram in different groups), and there was no relationship between faecal egg density and body condition score. Eggs of Nematodirus spp. were more common in sheep less than 1 yr of age, whereas those of the Trichostrongylidae were generally more common in adult sheep. Based on faecal egg counts, sheep grazing on common land close to permanent human settlements were generally no more heavily infected than those grazing the remote open plains. This could be due to a non-linear relationship between livestock numbers and stocking density. We suggest that cessation of strategic nematode control in the region following post-Soviet agricultural reform was offset by a general reduction in stocking density, such that parasite burdens remained low. However, recovery in livestock numbers is likely to lead to increased levels of infection and production loss unless sustainable control strategies are put in place.

What stock market returns to expect for the future?

PubMed

Diamond, P A

2000-01-01

In evaluating proposals for reforming Social Security that involve stock investments, the Office of the Chief Actuary (OCACT) has generally used a 7.0 percent real return for stocks. The 1994-96 Advisory Council specified that OCACT should use that return in making its 75-year projections of investment-based reform proposals. The assumed ultimate real return on Treasury bonds of 3.0 percent implies a long-run equity premium of 4.0 percent. There are two equity-premium concepts: the realized equity premium, which is measured by the actual rates of return; and the required equity premium, which investors expect to receive for being willing to hold available stocks and bonds. Over the past two centuries, the realized premium was 3.5 percent on average, but 5.2 percent for 1926 to 1998. Some critics argue that the 7.0 percent projected stock returns are too high. They base their arguments on recent developments in the capital market, the current high value of the stock market, and the expectation of slower economic growth. Increased use of mutual funds and the decline in their costs suggest a lower required premium, as does the rising fraction of the American public investing in stocks. The size of the decrease is limited, however, because the largest cost savings do not apply to the very wealthy and to large institutional investors, who hold a much larger share of the stock market's total value than do new investors. These trends suggest a lower equity premium for projections than the 5.2 percent of the past 75 years. Also, a declining required premium is likely to imply a temporary increase in the realized premium because a rising willingness to hold stocks tends to increase their price. Therefore, it would be a mistake during a transition period to extrapolate what may be a temporarily high realized return. In the standard (Solow) economic growth model, an assumption of slower long-run growth lowers the marginal product of capital if the savings rate is constant. But lower savings as growth slows should partially or fully offset that effect. The present high stock prices, together with projected slow economic growth, are not consistent with a 7.0 percent return. With a plausible level of adjusted dividends (dividends plus net share repurchases), the ratio of stock value to gross domestic product (GDP) would rise more than 20-fold over 75 years. Similarly, the steady-state Gordon formula--that stock returns equal the adjusted dividend yield plus the growth rate of stock prices (equal to that of GDP)--suggests a return of roughly 4.0 percent to 4.5 percent. Moreover, when relative stock values have been high, returns over the following decade have tended to be low. To eliminate the inconsistency posed by the assumed 7.0 percent return, one could assume higher GDP growth, a lower long-run stock return, or a lower short-run stock return with a 7.0 percent return on a lower base thereafter. For example, with an adjusted dividend yield of 2.5 percent to 3.0 percent, the market would have to decline about 35 percent to 45 percent in real terms over the next decade to reach steady state. In short, either the stock market is overvalued and requires a correction to justify a 7.0 percent return thereafter, or it is correctly valued and the long-run return is substantially lower than 7.0 percent (or some combination). This article argues that the "overvalued" view is more convincing, since the "correctly valued" hypothesis implies an implausibly small equity premium. Although OCACT could adopt a lower rate for the entire 75-year period, a better approach would be to assume lower returns over the next decade and a 7.0 percent return thereafter.

Multiscale sample entropy and cross-sample entropy based on symbolic representation and similarity of stock markets

NASA Astrophysics Data System (ADS)

Wu, Yue; Shang, Pengjian; Li, Yilong

2018-03-01

A modified multiscale sample entropy measure based on symbolic representation and similarity (MSEBSS) is proposed in this paper to research the complexity of stock markets. The modified algorithm reduces the probability of inducing undefined entropies and is confirmed to be robust to strong noise. Considering the validity and accuracy, MSEBSS is more reliable than Multiscale entropy (MSE) for time series mingled with much noise like financial time series. We apply MSEBSS to financial markets and results show American stock markets have the lowest complexity compared with European and Asian markets. There are exceptions to the regularity that stock markets show a decreasing complexity over the time scale, indicating a periodicity at certain scales. Based on MSEBSS, we introduce the modified multiscale cross-sample entropy measure based on symbolic representation and similarity (MCSEBSS) to consider the degree of the asynchrony between distinct time series. Stock markets from the same area have higher synchrony than those from different areas. And for stock markets having relative high synchrony, the entropy values will decrease with the increasing scale factor. While for stock markets having high asynchrony, the entropy values will not decrease with the increasing scale factor sometimes they tend to increase. So both MSEBSS and MCSEBSS are able to distinguish stock markets of different areas, and they are more helpful if used together for studying other features of financial time series.

Acoustic estimates of abundance and distribution of spawning lake trout on Sheboygan Reef in Lake Michigan

USGS Publications Warehouse

Warner, D.M.; Claramunt, R.M.; Janssen, J.; Jude, D.J.; Wattrus, N.

2009-01-01

Efforts to restore self-sustaining lake trout (Salvelinus namaycush) populations in the Laurentian Great Lakes have had widespread success in Lake Superior; but in other Great Lakes, populations of lake trout are maintained by stocking. Recruitment bottlenecks may be present at a number of stages of the reproduction process. To study eggs and fry, it is necessary to identify spawning locations, which is difficult in deep water. Acoustic sampling can be used to rapidly locate aggregations of fish (like spawning lake trout), describe their distribution, and estimate their abundance. To assess these capabilities for application to lake trout, we conducted an acoustic survey covering 22 km2 at Sheboygan Reef, a deep reef (<40 m summit) in southern Lake Michigan during fall 2005. Data collected with remotely operated vehicles (ROV) confirmed that fish were large lake trout, that lake trout were 1–2 m above bottom, and that spawning took place over specific habitat. Lake trout density exhibited a high degree of spatial structure (autocorrelation) up to a range of ~190 m, and highest lake trout and egg densities occurred over rough substrates (rubble and cobble) at the shallowest depths sampled (36–42 m). Mean lake trout density in the area surveyed (~2190 ha) was 5.8 fish/ha and the area surveyed contained an estimated 9500–16,000 large lake trout. Spatial aggregation in lake trout densities, similarity of depths and substrates at which high lake trout and egg densities occurred, and relatively low uncertainty in the lake trout density estimate indicate that acoustic sampling can be a useful complement to other sampling tools used in lake trout restoration research.

Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea

PubMed Central

Bauer, Robert Klaus; Demarcq, Hervé; Brisset, Blandine

2015-01-01

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD). PMID:26458254

Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea.

PubMed

Bauer, Robert Klaus; Fromentin, Jean-Marc; Demarcq, Hervé; Brisset, Blandine; Bonhommeau, Sylvain

2015-01-01

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD).

Do observed levels of exploitation from consumption-oriented and trophy-oriented fisheries reduce relative stock densities of Muskellunge below target levels in northern Wisconsin?

USGS Publications Warehouse

Faust, Matthew D.; Hansen, Michael J.

2017-01-01

Muskellunge anglers desire to catch large fish, and release rates by recreational anglers often approach 100% (Isermann et al. 2011). Muskellunge are also a culturally significant fish for Chippewa tribes and support a subsistence spearing fishery in Wisconsin’s Ceded Territory (Erickson 2007). Although Muskellunge populations within the state’s Ceded Territory are exposed to both angling and spearing fishery exploitation, Faust and Hansen (2016) suggested that under certain conditions (e.g., high minimum length limits (MLL) and low spearing exploitation) Muskellunge fisheries with disparate motivations could coexist (i.e., sufficient numbers of large individuals remained despite harvest from consumptive fishery), but noted that larger declines in trophy Muskellunge abundance were predicted at lower MLLs (e.g., 102-cm). Fisheries managers with the Wisconsin Department of Natural Resources (WDNR) wished to further understand how specific relative stock densities (RSD), used by the WDNR to define and monitor trophy Muskellunge fisheries, are reduced at exploitation rates commonly experienced by populations in northern Wisconsin. Similarly, understanding how trophy Muskellunge abundance may have declined under the previous statewide MLL (i.e., 86-cm) at these levels of exploitation was also desired. Thus, our objectives were to 1) determine if observed levels of angling and spearing exploitation reduced predicted RSD indices below thresholds used by the WDNR to define trophy Muskellunge fisheries for three typical Muskellunge growth potentials in northern Wisconsin across a variety of MLLs; and 2) quantify how numbers of trophy Muskellunge declined under an 86-cm MLL at observed levels of exploitation.

Changes in Managerial Decision on Pond Management to Adapt to Climate Anomalies in the Coastal Area of Pare-Pare Gulf, District of Pinrang

NASA Astrophysics Data System (ADS)

Fattah, M. H.; Busaeri, S. R.; Kasnir, M.; Siswanto

2017-08-01

The climate anomaly was adapted through the adjustment of tiger shrimp stocking patterns and optimum use of locally endemic Phronima Suppa (PS) to suit the season. Thus, the batches period determined was adjusted to suit climate change dynamics, reducing the shrimp stocking density down to 10.000 - 15.000 per ha and applying PS so the shrimp became tolerant of any environmental stress and pathogen infection. The knowledge of adaptation to climate anomalies, a learning outcome of the field school, managed to increase the average production of tiger shrimp to 217 kg/ha with an average receipt of IDR 22.60 million/ha.

Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks.

PubMed

Campbell, J Elliott; Moen, Jeremie C; Ney, Richard A; Schnoor, Jerald L

2008-03-01

Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively.

78 FR 24148 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-24

... Migratory Species (HMS) Fishery Management Plan (FMP) to address the results of recent shark stock... declared that the status of the dusky shark stock is still overfished and still experiencing overfishing (i.e., their stock status has not changed). On November 26, 2012, we published a proposed rule for...

76 FR 23794 - Stock Status Determination for Atlantic Highly Migratory Scalloped Hammerhead Shark

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-28

...) published in the North American Journal of Fisheries Management a stock assessment of the Atlantic... conservation and management measures to rebuild overfished stocks within 2 years of making this determination... to rebuilding the fishery within the shortest time possible in accordance with 16 U.S.C. 1854(e)(4...

Rapid diagnostic test supply chain and consumption study in Cabo Delgado, Mozambique: estimating stock shortages and identifying drivers of stock-outs.

PubMed

Hasselback, Leah; Crawford, Jessica; Chaluco, Timoteo; Rajagopal, Sharanya; Prosser, Wendy; Watson, Noel

2014-08-02

Malaria rapid diagnostic tests (RDTs) are particularly useful in low-resource settings where follow-through on traditional laboratory diagnosis is challenging or lacking. The availability of these tests depends on supply chain processes within the distribution system. In Mozambique, stock-outs of malaria RDTs are fairly common at health facilities. A longitudinal cross-sectional study was conducted to evaluate drivers of stock shortages in the Cabo Delgado province. Data were collected from purposively sampled health facilities, using monthly cross-sectional surveys between October 2011 and May 2012. Estimates of lost consumption (consumption not met due to stock-outs) served as the primary quantitative indicator of stock shortages. This is a better measure of the magnitude of stock-outs than binary indicators that only measure frequency of stock-outs at a given facility. Using a case study based methodology, distribution system characteristics were qualitatively analysed to examine causes of stock-outs at the provincial, district and health centre levels. 15 health facilities were surveyed over 120 time points. Stock-out patterns varied by data source; average monthly proportions of 59%, 17% and 17% of health centres reported a stock-out on stock cards, laboratory and pharmacy forms, respectively. Estimates of lost consumption percentage were significantly high; ranging from 0% to 149%; with a weighted average of 78%. Each ten-unit increase in monthly-observed consumption was associated with a nine-unit increase in lost consumption percentage indicating that higher rates of stock-outs occurred at higher levels of observed consumption. Causes of stock-outs included inaccurate tracking of lost consumption, insufficient sophistication in inventory management and replenishment, and poor process compliance by facility workers, all arguably stemming from inadequate attention to the design and implementation of the distribution system. Substantially high levels of RDT stock-outs were found in Cabo Delgado. Study findings point to a supply chain with a commendable degree of sophistication. However, insufficient attention paid to system design and implementation resulted in deteriorating performance in areas of increased need. In such settings fast moving commodities like malaria RDTs can call attention to supply chain vulnerabilities, the findings from which can be used to address other slower moving health commodities.

Rapid diagnostic test supply chain and consumption study in Cabo Delgado, Mozambique: estimating stock shortages and identifying drivers of stock-outs

PubMed Central

2014-01-01

Background Malaria rapid diagnostic tests (RDTs) are particularly useful in low-resource settings where follow-through on traditional laboratory diagnosis is challenging or lacking. The availability of these tests depends on supply chain processes within the distribution system. In Mozambique, stock-outs of malaria RDTs are fairly common at health facilities. A longitudinal cross-sectional study was conducted to evaluate drivers of stock shortages in the Cabo Delgado province. Methods Data were collected from purposively sampled health facilities, using monthly cross-sectional surveys between October 2011 and May 2012. Estimates of lost consumption (consumption not met due to stock-outs) served as the primary quantitative indicator of stock shortages. This is a better measure of the magnitude of stock-outs than binary indicators that only measure frequency of stock-outs at a given facility. Using a case study based methodology, distribution system characteristics were qualitatively analysed to examine causes of stock-outs at the provincial, district and health centre levels. Results 15 health facilities were surveyed over 120 time points. Stock-out patterns varied by data source; average monthly proportions of 59%, 17% and 17% of health centres reported a stock-out on stock cards, laboratory and pharmacy forms, respectively. Estimates of lost consumption percentage were significantly high; ranging from 0% to 149%; with a weighted average of 78%. Each ten-unit increase in monthly-observed consumption was associated with a nine-unit increase in lost consumption percentage indicating that higher rates of stock-outs occurred at higher levels of observed consumption. Causes of stock-outs included inaccurate tracking of lost consumption, insufficient sophistication in inventory management and replenishment, and poor process compliance by facility workers, all arguably stemming from inadequate attention to the design and implementation of the distribution system. Conclusions Substantially high levels of RDT stock-outs were found in Cabo Delgado. Study findings point to a supply chain with a commendable degree of sophistication. However, insufficient attention paid to system design and implementation resulted in deteriorating performance in areas of increased need. In such settings fast moving commodities like malaria RDTs can call attention to supply chain vulnerabilities, the findings from which can be used to address other slower moving health commodities. PMID:25086645

Effects of stocking density and string provision on welfare-related measures in commercial broiler chickens in windowed houses.

PubMed

Bailie, C L; Ijichi, C; O'Connell, N E

2018-05-01

Lower stocking densities (SD) are sometimes used in windowed houses for broilers as part of systems designed to produce high-welfare products. However, there is little scientific information on the effects of SD on welfare-related measures in broilers in windowed houses, and on whether these effects are influenced by environmental enrichment. Commercial windowed broiler chicken houses were assigned to 4 target SD (30, 32, 34, and 36 kg/m2) and 2 levels of access to string [+S (one piece per 1,000 birds/house), -S] in a 4 × 2 factorial arrangement. Treatments were applied in one of 4 houses on each of 2 farms, and replicated over 10 production cycles. Levels of lying behavior, apparent fear-related behavior, and gait score were observed in wk 3 to 5. The incidence and severity of dermatitis lesions were assessed at d 30 and at slaughter. Environmental and production performance parameters also were measured. No significant treatment effects were obtained for levels of lying or fear-related behavior, final body weight, presence of dermatitis lesions at slaughter, or percentage of downgraded carcasses. There were no significant treatment effects on measures of gait, but the percentage of birds with a gait score of ≥2 tended to increase at higher SD. The severity of dermatitis lesions at d 30 increased with increasing SD, and was significantly greater at densities of 34 and 36 kg/m2 than of 30 kg/m2. Litter moisture content was not significantly affected by treatment, which may have reflected a numerical decline in water consumption with increasing SD. Results suggest that increasing SD is a risk factor for more severe dermatitis; however, increasing density from 30 to 32 kg/m2 did not significantly affect this variable. In addition, the proportion of lame birds, levels of lying behavior, and performance were not significantly affected by increasing SD. Providing suspended string at typical commercial levels did not have beneficial effects on welfare-related measures, and further research should perhaps investigate effects of greater levels of provision.

Multitemporal mapping of peri-urban carbon stocks and soil sealing from satellite data.

PubMed

Villa, Paolo; Malucelli, Francesco; Scalenghe, Riccardo

2018-01-15

Peri-urbanisation is the expansion of compact urban areas towards low-density settlements. This phenomenon directly challenges the agricultural landscape multifunctionality, including its carbon (C) storage capacity. Using satellite data, we mapped peri-urban C stocks in soil and built-up surfaces over three areas from 1993 to 2014 in the Emilia-Romagna region, Italy: a thinly populated area around Piacenza, an intermediate-density area covering the Reggio Emilia-Modena conurbation and a densely anthropized area developing along the coast of Rimini. Satellite-derived maps enabled the quantitative analysis of spatial and temporal features of urban growth and soil sealing, expressed as the ratio between C in built-up land and organic C in soils (Cc/Co). The three areas show substantial differences in C stock balance and soil sealing evolution. In Piacenza (Cc/Co=0.07 in 1993), although questioned by late industrial expansion and connected residential sprawl (Cc/Co growth by 38%), most of the new urbanisation spared the best rural soils. The Reggio Emilia-Modena conurbation, driven by the polycentricism of the area and the heterogeneity of economic sectors (Cc/Co rising from 0.08 to 0.14 from 1993 to 2014), balances sprawl and densification. Rimini, severely sealed since the 1960s (Cc/Co=0.23 in 1993), densifies its existing settlements and develops an industrial expansion of the hinterland, with Cc/Co growth accelerating from +15% before 2003 to +36% for the last decade. Copyright © 2017 Elsevier B.V. All rights reserved.

Agonistic behavior among three stocked trout species in a novel reservoir fish community

USGS Publications Warehouse

Budy, Phaedra; Hafen, Konrad

2015-01-01

The popularity of reservoirs to support sport fisheries has led to the stocking of species that did not co-evolve, creating novel reservoir fish communities. In Utah, the Bear Lake strain of Bonneville Cutthroat Trout Oncorhynchus clarkii utah and tiger trout (female Brown Trout Salmo trutta × male Brook Trout Salvelinus fontinalis) are being more frequently added to a traditional stocking regimen consisting primarily of Rainbow TroutO. mykiss. Interactions between these three predatory species are not well understood, and studies evaluating community interactions have raised concern for an overall decrease of trout condition. To evaluate the potential for negative interactions among these species, we tested aggression in laboratory aquaria using three-species and pairwise combinations at three densities. Treatments were replicated before and after feeding. During the three-species trials Rainbow Trout initiated 24.8 times more aggressive interactions than Cutthroat Trout and 10.2 times more aggressive interactions than tiger trout, and tiger trout exhibited slightly (1.9 times) more aggressive initiations than Cutthroat Trout. There was no significant difference in behavior before versus after feeding for any species, and no indication of increased aggression at higher densities. Although Rainbow Trout in aquaria may benefit from their bold, aggressive behavior, given observations of decreased relative survival in the field, these benefits may be outweighed in reservoirs, possibly through unnecessary energy expenditure and exposure to predators.

The spatial distribution of soil organic carbon in tidal wetland soils of the continental United States.

PubMed

Hinson, Audra L; Feagin, Rusty A; Eriksson, Marian; Najjar, Raymond G; Herrmann, Maria; Bianchi, Thomas S; Kemp, Michael; Hutchings, Jack A; Crooks, Steve; Boutton, Thomas

2017-12-01

Tidal wetlands contain large reservoirs of carbon in their soils and can sequester carbon dioxide (CO 2 ) at a greater rate per unit area than nearly any other ecosystem. The spatial distribution of this carbon influences climate and wetland policy. To assist with international accords such as the Paris Climate Agreement, national-level assessments such as the United States (U.S.) National Greenhouse Gas Inventory, and regional, state, local, and project-level evaluation of CO 2 sequestration credits, we developed a geodatabase (CoBluCarb) and high-resolution maps of soil organic carbon (SOC) distribution by linking National Wetlands Inventory data with the U.S. Soil Survey Geographic Database. For over 600,000 wetlands, the total carbon stock and organic carbon density was calculated at 5-cm vertical resolution from 0 to 300 cm of depth. Across the continental United States, there are 1,153-1,359 Tg of SOC in the upper 0-100 cm of soils across a total of 24 945.9 km 2 of tidal wetland area, twice as much carbon as the most recent national estimate. Approximately 75% of this carbon was found in estuarine emergent wetlands with freshwater tidal wetlands holding about 19%. The greatest pool of SOC was found within the Atchafalaya/Vermilion Bay complex in Louisiana, containing about 10% of the U.S. total. The average density across all tidal wetlands was 0.071 g cm -3 across 0-15 cm, 0.055 g cm -3 across 0-100 cm, and 0.040 g cm -3 at the 100 cm depth. There is inherent variability between and within individual wetlands; however, we conclude that it is possible to use standardized values at a range of 0-100 cm of the soil profile, to provide first-order quantification and to evaluate future changes in carbon stocks in response to environmental perturbations. This Tier 2-oriented carbon stock assessment provides a scientific method that can be copied by other nations in support of international requirements. © 2017 John Wiley & Sons Ltd.

An analysis of carbon and radiocarbon profiles across a range ecosystems types

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; Strahm, B. D.; Sanclements, M.

2016-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of mineralogical parameters on soil C stocks and turnover and their relative importance in comparison to climatic variables. Results are presented for a total of 11 NEON sites, spanning Alfisols, Entisols, Mollisols and Spodosols. Soils were sampled by genetic horizon, density separated according to density fractionation: light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon concentrations of the heavy fraction (mineral adsorbed) were significantly, though weakly, correlated with pH (r2 = 0.35, p = 0.02), though C concentrations were not. Data suggest an important role for both aggregation and soil chemistry in regulating soil C cycling across a diversity of soil orders. The current presented results serve as a preliminary report on a project spanning 40 NEON sites and a range of physiochemical analyses.

Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic.

PubMed

Kauffman, J Boone; Heider, Chris; Norfolk, Jennifer; Payton, Frederick

2014-04-01

Mangroves are recognized to possess a variety of ecosystem services including high rates of carbon sequestration and storage. Deforestation and conversion of these ecosystems continue to be high and have been predicted to result in significant carbon emissions to the atmosphere. Yet few studies have quantified the carbon stocks or losses associated with conversion of these ecosystems. In this study we quantified the ecosystem carbon stocks of three common mangrove types of the Caribbean as well as those of abandoned shrimp ponds in areas formerly occupied by mangrove-a common land-use conversion of mangroves throughout the world. In the mangroves of the Montecristi Province in Northwest Dominican Republic we found C stocks ranged from 706 to 1131 Mg/ha. The medium-statured mangroves (3-10 m in height) had the highest C stocks while the tall (> 10 m) mangroves had the lowest ecosystem carbon storage. Carbon stocks of the low mangrove (shrub) type (< 3 m) were relatively high due to the presence of carbon-rich soils as deep as 2 m. Carbon stocks of abandoned shrimp ponds were 95 Mg/ha or approximately 11% that of the mangroves. Using a stock-change approach, the potential emissions from the conversion of mangroves to shrimp ponds ranged from 2244 to 3799 Mg CO2e/ha (CO2 equivalents). This is among the largest measured C emissions from land use in the tropics. The 6260 ha of mangroves and converted mangroves in the Montecristi Province are estimated to contain 3,841,490 Mg of C. Mangroves represented 76% of this area but currently store 97% of the carbon in this coastal wetland (3,696,722 Mg C). Converted lands store only 4% of the total ecosystem C (144,778 Mg C) while they comprised 24% of the area. By these metrics the replacement of mangroves with shrimp and salt ponds has resulted in estimated emissions from this region totaling 3.8 million Mg CO2e or approximately 21% of the total C prior to conversion. Given the high C stocks of mangroves, the high emissions from their conversion, and the other important functions and services they provide, their inclusion in climate-change mitigation strategies is warranted.

Estimating vegetative biomass from LANDSAT-1 imagery for range management

NASA Technical Reports Server (NTRS)

Seevers, P. M.; Drew, J. V.; Carlson, M. P.

1975-01-01

Evaluation of LANDSAT-1, band 5 data for use in estimation of vegetative biomass for range management decisions was carried out for five selected range sites in the Sandhills region of Nebraska. Analysis of sets of optical density-vegetative biomass data indicated that comparisons of biomass estimation could be made within one frame but not between frames without correction factors. There was high correlation among sites within sets of radiance value-vegetative biomass data and also between sets, indicating comparisons of biomass could be made within and between frames. Landsat-1 data are shown to be a viable alternative to currently used methods of determining vegetative biomass production and stocking rate recommendations for Sandhills rangeland.

77 FR 8759 - International Fisheries; Western and Central Pacific Fisheries for Highly Migratory Species...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-15

... Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central... Management Area'' (Eastern SMA) and requirements relating to discards from purse seine fishing vessels. This... and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean (Commission or...

Dynamics of sediment carbon stocks across intertidal wetland habitats of Moreton Bay, Australia.

PubMed

Hayes, Matthew A; Jesse, Amber; Hawke, Bruce; Baldock, Jeff; Tabet, Basam; Lockington, David; Lovelock, Catherine E

2017-10-01

Coastal wetlands are known for high carbon storage within their sediments, but our understanding of the variation in carbon storage among intertidal habitats, particularly over geomorphological settings and along elevation gradients, is limited. Here, we collected 352 cores from 18 sites across Moreton Bay, Australia. We assessed variation in sediment organic carbon (OC) stocks among different geomorphological settings (wetlands within riverine settings along with those with reduced riverine influence located on tide-dominated sand islands), across elevation gradients, with distance from shore and among habitat and vegetation types. We used mid-infrared (MIR) spectroscopy combined with analytical data and partial least squares regression to quantify the carbon content of ~2500 sediment samples and provide fine-scale spatial coverage of sediment OC stocks to 150 cm depth. We found sites in river deltas had larger OC stocks (175-504 Mg/ha) than those in nonriverine settings (44-271 Mg/ha). Variation in OC stocks among nonriverine sites was high in comparison with riverine and mixed geomorphic settings, with sites closer to riverine outflow from the east and south of Moreton Bay having higher stocks than those located on the sand islands in the northwest of the bay. Sediment OC stocks increased with elevation within nonriverine settings, but not in riverine geomorphic settings. Sediment OC stocks did not differ between mangrove and saltmarsh habitats. OC stocks did, however, differ between dominant species across the research area and within geomorphic settings. At the landscape scale, the coastal wetlands of the South East Queensland catchments (17,792 ha) are comprised of approximately 4,100,000-5,200,000 Mg of sediment OC. Comparatively high variation in OC storage between riverine and nonriverine geomorphic settings indicates that the availability of mineral sediments and terrestrial derived OC may exert a strong influence over OC storage potential across intertidal wetland systems. © 2017 John Wiley & Sons Ltd.

Lead-lag relationships between stock and market risk within linear response theory

NASA Astrophysics Data System (ADS)

Borysov, Stanislav; Balatsky, Alexander

2015-03-01

We study historical correlations and lead-lag relationships between individual stock risks (standard deviation of daily stock returns) and market risk (standard deviation of daily returns of a market-representative portfolio) in the US stock market. We consider the cross-correlation functions averaged over stocks, using historical stock prices from the Standard & Poor's 500 index for 1994-2013. The observed historical dynamics suggests that the dependence between the risks was almost linear during the US stock market downturn of 2002 and after the US housing bubble in 2007, remaining at that level until 2013. Moreover, the averaged cross-correlation function often had an asymmetric shape with respect to zero lag in the periods of high correlation. We develop the analysis by the application of the linear response formalism to study underlying causal relations. The calculated response functions suggest the presence of characteristic regimes near financial crashes, when individual stock risks affect market risk and vice versa. This work was supported by VR 621-2012-2983.

Baltic Sea Blue Carbon: Role of environmental factors influencing the carbon sink capacity of eelgrass (Zostera marina) meadows.

NASA Astrophysics Data System (ADS)

Röhr, E.; Holmer, M.; Boström, C.

2016-02-01

Although the global seagrass coverage area is less than 0.2 % of the worlds ocean floor, the carbon sink capacity of seagrasses may account up to 18 % of oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. Recent studies have shown considerable variation in the global estimates for seagrass meadow Corg accumulation rates and stocks, and indicate lack of understanding the factors influencing this variability. We sampled 20 eelgrass (Zostera marina) meadows in Finland and Denmark to study the variation in Corg accumulation rates and stocks within the Baltic Sea area. The study sites in both regions spanned a gradient from sheltered to exposed locations. The estimates for Corg accumulation rates at the Finnish eelgrass meadows were two orders of magnitude lower than the estimates for the Danish sites. The Corg stock integrated over the top 25 cm of sediment showed similar pattern, suggesting that the Finnish eelgrass meadows are carbon sources rather than carbon sinks, and the produced Corg is exported from the meadows. In contrast, at the Danish sites both Corg accumulation rates and areal Corg stock was more varying suggesting, that in this region the meadows function both as carbon sinks and sources. Our analysis further showed that a large percentage (> 55 %) of the variation in the Corg stocks was explained by sediment characteristics (density, fraction of silt and grain size distribution). In addition, the contribution of Zostera marina detritus to the sediment Corg pool explained >14 % of the variation in the Corg stocks. In order to get more reliable regional and global estimates of the role of seagrass meadows in the ocean carbon cycle, more studies accounting for the full range of environmental and species characteristics are urgently needed.

Contemporary management issues confronting fisheries science

NASA Astrophysics Data System (ADS)

Frank, Kenneth T.; Brickman, David

2001-06-01

Stock collapses have occurred worldwide. The most frequently cited cause is over-fishing, suggesting that fisheries management has been ineffective in controlling exploitation rates. The progression of a fishery from an over-exploited to a collapsed state involves impairment of the reproductive capacity of the target species, i.e. recruitment over-fishing. In many cases, this occurs by reduction of the spawning stock biomass (SSB) through the systematic elimination of spawning components within a stock complex. While operational definitions of minimum levels of SSB have been developed, they have seldom been applied and never adopted in a Canadian groundfish management context. The answer to the question of how much is enough to perpetuate a stock under exploitation has been illusive. Serebryakov [J. Cons. Int. Explor. Mer, 47 (1990) 267] has advocated definition of critical levels of SSB based on survival rates (R/SSB). We review his method and discuss the utility of the approach. An alternative approach to the problem of estimating minimum SSB is through a fundamental revision of the traditional stock and recruitment relationship. Explicit theoretical SSB thresholds below which reproduction/recruitment is severely impaired based upon density-dependent mating success (or Allee effects) is considered a superior approach to the question of how much is enough because of its ecological grounding. However, the successful application of this approach will require re-definition of the space/time scales of the management unit. Finally, support is growing for the establishment of closed areas or "no-take zones" as an alternative approach to managing the problems of fishing a stock complex by enabling sub-populations to escape fishing. While the expected benefits of areas protected from fishing are numerous, clear demonstrations of benefits of such areas in marine temperate ecosystems are lacking. In fact, unintended negative consequences may result from such actions.

Legacy effects of grassland management on soil carbon to depth.

PubMed

Ward, Susan E; Smart, Simon M; Quirk, Helen; Tallowin, Jerry R B; Mortimer, Simon R; Shiel, Robert S; Wilby, Andrew; Bardgett, Richard D

2016-08-01

The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management. © 2016 John Wiley & Sons Ltd.

Cross-sectional test of the Fama-French three-factor model: Evidence from Bangladesh stock market

NASA Astrophysics Data System (ADS)

Hasan, Md. Zobaer; Kamil, Anton Abdulbasah

2014-09-01

Stock market is an important part of a country's economy. It supports the country's economic development and progress by encouraging the efficiency and profitability of firms. This research was designed to examine the risk-return association of companies in the Dhaka Stock Exchange (DSE) market of Bangladesh by using the Fama-French three-factor model structure. The model is based on three factors, which are stock beta, SMB (difference in returns of the portfolio with small market capitalisation minus that with big market capitalisation) and HML (difference in returns of the portfolio with high book-to-market ratio minus that with low book-to-market ratio). This study focused on the DSE market as it is one of the frontier emerging stock markets of South Asia. For this study, monthly stock returns from 71 non-financial companies were used for the period of January 2002 to December 2011. DSI Index was used as a proxy for the market portfolio and Bangladesh government 3-Month T-bill rate was used as the proxy for the risk-free asset. It was found that large capital stocks outperform small capital stocks and stocks with lower book-to-market ratios outperform stocks with higher book-to-market ratios in the context of Bangladesh stock market.

A forward-looking, national-scale remote sensing-based model of tidal marsh aboveground carbon stocks

NASA Astrophysics Data System (ADS)

Holmquist, J. R.; Byrd, K. B.; Ballanti, L.; Nguyen, D.; Simard, M.; Windham-Myers, L.; Thomas, N.

2017-12-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our goal was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). To meet this objective we developed the first national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest algorithm we tested Sentinel-1 radar backscatter metrics and Landsat vegetation indices as predictors of biomass. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n=409, RMSE=310 g/m2, 10.3% normalized RMSE), successfully predicted biomass and carbon for a range of marsh plant functional types defined by height, leaf angle and growth form. Model error was reduced by scaling field measured biomass by Landsat fraction green vegetation derived from object-based classification of National Agriculture Imagery Program imagery. We generated 30m resolution biomass maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map for each region. With a mean plant %C of 44.1% (n=1384, 95% C.I.=43.99% - 44.37%) we estimated mean aboveground carbon densities (Mg/ha) and total carbon stocks for each wetland type for each region. Louisiana palustrine emergent marshes had the highest C density (2.67 ±0.08 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ±0.06 Mg/ha). This modeling and data synthesis effort will allow for aboveground C stocks in tidal marshes to be included for the first time in the 2018 U.S. EPA Greenhouse Gas Inventory for coastal wetlands. As technical barriers have been reduced through the availability of free post-processed satellite data, cloud computing platforms and open source software, this approach can potentially be applied globally as well.

Is there any overtrading in stock markets? The moderating role of big five personality traits and gender in a unilateral trend stock market.

PubMed

Zhang, Jian; Wang, Haocheng; Wang, Limin; Liu, Shuyi

2014-01-01

Overtrading is a common anomaly among stock investors. This study examines the relationship between overtrading and investment returns and the impact of the Big Five traits and gender on overtrading in a unilateral trend stock market using a simulated stock investment system. The data were derived from a sample of undergraduates from six universities who performed in a simulated stock investment situation and had their personality traits measured by the Big Five Personality Questionnaire. The results indicate that: (1) Overtrading was significant in rising stock markets, but not significant in falling markets. (2) The degree of female investors who overtraded was significant in rising markets. (3) The degree of overtrading investors who were high in extroversion or agreeableness was significant in rising markets. The implications of these results for more effective investment strategies are discussed.

Is There Any Overtrading in Stock Markets? The Moderating Role of Big Five Personality Traits and Gender in a Unilateral Trend Stock Market

PubMed Central

Zhang, Jian; Wang, Haocheng; Wang, Limin; Liu, Shuyi

2014-01-01

Overtrading is a common anomaly among stock investors. This study examines the relationship between overtrading and investment returns and the impact of the Big Five traits and gender on overtrading in a unilateral trend stock market using a simulated stock investment system. The data were derived from a sample of undergraduates from six universities who performed in a simulated stock investment situation and had their personality traits measured by the Big Five Personality Questionnaire. The results indicate that: (1) Overtrading was significant in rising stock markets, but not significant in falling markets. (2) The degree of female investors who overtraded was significant in rising markets. (3) The degree of overtrading investors who were high in extroversion or agreeableness was significant in rising markets. The implications of these results for more effective investment strategies are discussed. PMID:24475235

Power Laws and Market Crashes ---Empirical Laws on Bursting Bubbles---

NASA Astrophysics Data System (ADS)

Kaizoji, T.

In this paper, we quantitatively investigate the statistical properties of a statistical ensemble of stock prices. We selected 1200 stocks traded on the Tokyo Stock Exchange, and formed a statistical ensemble of daily stock prices for each trading day in the 3-year period from January 4, 1999 to December 28, 2001, corresponding to the period of the forming of the internet bubble in Japn, and its bursting in the Japanese stock market. We found that the tail of the complementary cumulative distribution function of the ensemble of stock prices in the high value of the price is well described by a power-law distribution, P (S > x) ˜ x^{-α}, with an exponent that moves in the range of 1.09 < α < 1.27. Furthermore, we found that as the power-law exponents α approached unity, the bubbles collapsed. This suggests that Zipf's law for stock prices is a sign that bubbles are going to burst.

Species-specific preferences of German recreational anglers for freshwater fishing experiences, with emphasis on the intrinsic utilities of fish stocking and wild fishes.

PubMed

Arlinghaus, R; Beardmore, B; Riepe, C; Meyerhoff, J; Pagel, T

2014-12-01

To answer the question, whether anglers have an intrinsic preference for stocking or a preference for catch outcomes (e.g. catch rates) believed to be maintained by stocking, a discrete choice experiment was conducted among a sample of anglers (n = 1335) in Lower Saxony, Germany. After controlling for catch aspects of the fishing experience, no significant influence of two stocking attributes (stocking frequency and composition of the catch in terms of wild v. hatchery fishes) on the utility gained from fishing was found for any of the freshwater species that were studied. It was concluded that the previously documented large appreciation of fish stocking by anglers may be indicative of an underlying preference for sufficiently high catches rather than reflect an intrinsic preference for stocking or the catching of wild fishes per se. © 2014 The Fisheries Society of the British Isles.

Increasing biomass carbon stocks in trees outside forests in China over the last three decades

NASA Astrophysics Data System (ADS)

Guo, Z. D.; Hu, H. F.; Pan, Y. D.; Birdsey, R. A.; Fang, J. Y.

2014-08-01

Trees outside forests (TOF) play important roles in national economies, ecosystem services, and international efforts for mitigating climate warming. Detailed assessment of the dynamics of carbon (C) stocks in China's TOF is necessary for fully evaluating the role of the country's trees in the national C cycle. This study is the first to explore the changes in biomass C stocks of China's TOF over the last three decades, using the national forest inventory data in six periods from 1977 to 2008. According to the definition of the forest inventory, China's TOF could be categorized into three groups: woodlands, shrubberies, and trees on non-forest land (including four-side greening trees, defined in the article, and scattered trees). We estimated biomass C stocks of woodlands and trees on non-forest land by using the provincial biomass-volume conversion equations derived from the data of low-canopy forests, and estimated the biomass C stocks of shrubberies using the provincial mean biomass density. Total TOF biomass C stock increased by 62.7% from 823 Tg C (1 Tg = 1012 g) in the initial period of 1977-1981 to 1339 Tg C in the last period of 2004-2008. As a result, China's TOF have accumulated biomass C of 516 Tg during the study period, with 12, 270, and 234 Tg in woodlands, shrubberies, and trees on non-forest land, respectively. The annual biomass C sink of China's TOF averaged 19.1 Tg C yr-1, offsetting 2.1% of the contemporary fossil-fuel CO2 emissions in the country. These estimates are equal to 16.5-20.7% of the contemporary total forest biomass C stock and 27.2% of the total forest biomass C sink in the country, suggesting that TOF are substantial components in China's tree C budget.

A new detailed map of total phosphorus stocks in Australian soil.

PubMed

Viscarra Rossel, Raphael A; Bui, Elisabeth N

2016-01-15

Accurate data are needed to effectively monitor environmental condition, and develop sound policies to plan for the future. Globally, current estimates of soil total phosphorus (P) stocks are very uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of total P in Australian soil. Data from several sources were harmonized to produce the most comprehensive inventory of total P in soil of the continent. They were used to produce fine spatial resolution continental maps of total P in six depth layers by combining the bootstrap, a decision tree with piecewise regression on environmental variables and geostatistical modelling of residuals. Values of percent total P were predicted at the nodes of a 3-arcsecond (approximately 90 m) grid and mapped together with their uncertainties. We combined these predictions with those for bulk density and mapped the total soil P stock in the 0-30 cm layer over the whole of Australia. The average amount of P in Australian topsoil is estimated to be 0.98 t ha(-1) with 90% confidence limits of 0.2 and 4.2 t ha(-1). The total stock of P in the 0-30 cm layer of soil for the continent is 0.91 Gt with 90% confidence limits of 0.19 and 3.9 Gt. The estimates are the most reliable approximation of the stock of total P in Australian soil to date. They could help improve ecological models, guide the formulation of policy around food and water security, biodiversity and conservation, inform future sampling for inventory, guide the design of monitoring networks, and provide a benchmark against which to assess the impact of changes in land cover, land use and management and climate on soil P stocks and water quality in Australia. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

The Potential for Spatial Distribution Indices to Signal Thresholds in Marine Fish Biomass

PubMed Central

Reuchlin-Hugenholtz, Emilie

2015-01-01

The frequently observed positive relationship between fish population abundance and spatial distribution suggests that changes in distribution can be indicative of trends in abundance. If contractions in spatial distribution precede declines in spawning stock biomass (SSB), spatial distribution reference points could complement the SSB reference points that are commonly used in marine conservation biology and fisheries management. When relevant spatial distribution information is integrated into fisheries management and recovery plans, risks and uncertainties associated with a plan based solely on the SSB criterion would be reduced. To assess the added value of spatial distribution data, we examine the relationship between SSB and four metrics of spatial distribution intended to reflect changes in population range, concentration, and density for 10 demersal populations (9 species) inhabiting the Scotian Shelf, Northwest Atlantic. Our primary purpose is to assess their potential to serve as indices of SSB, using fisheries independent survey data. We find that metrics of density offer the best correlate of spawner biomass. A decline in the frequency of encountering high density areas is associated with, and in a few cases preceded by, rapid declines in SSB in 6 of 10 populations. Density-based indices have considerable potential to serve both as an indicator of SSB and as spatially based reference points in fisheries management. PMID:25789624

Standard and Poor's How to Invest. A Handbook for Buying and Selling Stocks and Bonds.

ERIC Educational Resources Information Center

Standard & Poor's Corp., New York, NY.

Designed for the general public and possibly suitable also for high school and college economic students, the handbook gives general information about investing in the stock market. Arranged into seven sections, the handbook discusses the typical shareholder, common and preferred stocks, buying and selling bonds, how to develop a personal…

The Wilderness Act and fish stocking: an overview of legislation, judicial interpretation, and agency implementation

Treesearch

Peter Landres; Shannon Meyer; Sue Matthews

2001-01-01

Many high-elevation lakes in designated wilderness are stocked with native and nonnative fish by state fish and game agencies to provide recreational fishing opportunities. In several areas, this practice has become controversial with state wildlife managers who support historical recreational use of wilderness, federal wilderness managers who assert that stocking...

High-resolution forest carbon stocks and emissions in the Amazon

Treesearch

G. P. Asner; George V. N. Powell; Joseph Mascaro; David E. Knapp; John K. Clark; James Jacobson; Ty Kennedy-Bowdoin; Aravindh Balaji; Guayana Paez-Acosta; Eloy Victoria; Laura Secada; Michael Valqui; R. Flint. Hughes

2010-01-01

Efforts to mitigate climate change through the Reduced Emissions from Deforestation and Degradation (REDD) depend on mapping and monitoring of tropical forest carbon stocks and emissions over large geographic areas. With a new integrated use of satellite imaging, airborne light detection and ranging, and field plots, we mapped aboveground carbon stocks and emissions at...

Nutrient modeling for a semi-intensive IMC pond: an MS-Excel approach.

PubMed

Ray, Lala I P; Mal, B C; Moulick, S

2017-11-01

Semi-intensive Indian Major Carp (IMC) culture was practised in polythene lined dugout ponds at the Aquacultural Farm of Indian Institute of Technology, Kharagpur, West Bengal for 3 consecutive years at three different stocking densities (S.D), viz., 20,000, 35,000 and 50,000 numbers of fingerlings per hectare of water spread area. Fingerlings of Catla, Rohu and Mrigal were raised at a stocking ratio of 4:3:3. Total ammonia nitrogen (TAN) value along with other fishpond water quality parameters was monitored at 1 day intervals to ensure a good water ecosystem for a better fish growth. Water exchange was carried out before the TAN reached the critical limit. Field data on TAN obtained from the cultured fishponds stocked with three different stocking densities were used to study the dynamics of TAN. A developed model used to study the nutrient dynamics in shrimp pond was used to validate the observed data in the IMC pond ecosystem. Two years of observed TAN data were used to calibrate the spreadsheet model and the same model was validated using the third year observed data. The manual calibration based on the trial and error process of parameters adjustments was used and several simulations were performed by changing the model parameters. After adjustment of each parameter, the simulated and measured values of the water quality parameters were compared to judge the improvement in the model prediction. Forward finite difference discretization method was used in a MS-Excel spreadsheet to calibrate and validate the model for obtaining the TAN levels during the culture period. Observed data from the cultured fishponds of three different S.D were used to standardize 13 model parameters. The efficiency of the developed spreadsheet model was found to be more than 90% for the TAN estimation in the IMC cultured fishponds.

75 FR 48927 - Sierra National Forest, Bass Lake Ranger District, California, Fish Camp Project

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-12

... stocked and thinning is needed. This thinning is needed to reduce inter-tree competition and improve tree... densities are above what can be sustained, with inter-tree competition increasing and tree vigor beginning... communities and reduce inter tree competition to improve tree vigor and increase stand resistance to drought...

A silvicultural guide for developing a sugarbush

Treesearch

Kenneth F. Lancaster; Russell S. Walters; Frederick M. Laing; Raymond T. Foulds

1974-01-01

A practical guide for the management of a sugarbush. Guidelines are established for the manipulation of stand density and stocking to promote the development of healthy vigorous trees with deep, wide crowns, the necessary attributes for highest possible yield of sugar-rich sap. Specific treatments are prescribed for sapling, poletimber and small sawtimber stands and a...

The effect of three space allowances on the physiology and behavior of weaned pigs during transportation

USDA-ARS?s Scientific Manuscript database

Stocking density is an important aspect of transport which could affect animal health and welfare, especially in pigs simultaneously experiencing weaning stress. The objective of this research was to evaluate the effect of three different space allowances on the physiology and behavior of weaned pig...

FVS out of the box - assembly required

Treesearch

Don Vandendriesche

2010-01-01

The Forest Vegetation Simulator (FVS) is a prominent growth and yield model used for forecasting stand dynamics. However, users need to be aware of model behavior regarding stocking density, tree senescence, and understory recruitment; otherwise over long projections, FVS tends to concentrate substantial growth on few survivor trees. If the intent is to forecast...

Historical trajectories and restoration strategies for the Mississippi River alluvial valley

Treesearch

Brice B. Hanberry; John M. Kabrick; Hong S. He; Brian J. Palik

2012-01-01

Unlike upland forests in the eastern United States, little research is available about the composition and structure of bottomland forests before Euro-American settlement. To provide a historical reference encompassing spatial variation for the Lower Mississippi River Alluvial Valley, we quantified forest types, species distributions, densities, and stocking of...

Colonization of internal organs by Salmonella serovars Heidelberg and Typhimurium in experimentally infected laying hens housed in enriched colony cages at different stocking densities

USDA-ARS?s Scientific Manuscript database

Contaminated eggs produced by infected commercial laying flocks are often implicated as sources of human infections with Salmonella Enteritidis, but Salmonella serovars Heidelberg and Typhimurium have also been significantly associated with egg-transmitted illness. Contamination of the edible conten...

Crown size relationships for black willow in the Lower Mississippi Alluvial Valley

Treesearch

Jamie L. Schuler; Bradley Woods; Joshua Adams; Ray Souter

2015-01-01

Growing space requirements derived from maximum and minimum crown sizes have been identified for many southern hardwood species. These requirements help managers assess stocking levels, schedule intermediate treatments, and even assist in determining planting densities. Throughout the Mississippi Alluvial Valley, black willow (Salix nigra Marsh.) stands are common...

Charcoal in organic horizon and surface mineral soil in a boreal forest postfire chronosequence of Western Quebec: stocks, depth distribution, chemical properties and a synthesis of related studies

NASA Astrophysics Data System (ADS)

Preston, Caroline M.; Simard, Martin; Bergeron, Yves; Bernard, Guy M.; Wasylishen, Roderick E.

2017-11-01

Wildfires are a major driver of carbon stocks and ecosystem development in Canadian boreal forests, but there is little information on amounts and properties of the charcoal produced. Using data and samples available from a previous study, we determined amounts, depth distribution and chemical properties of visually-determined charcoal (> 2 mm) in a boreal chronosequence in the Abitibi region of Quebec, Canada. Sites ranged from 24 to 2355 years since fire (ysf) and originated from low- and high-severity soil burns (> 5 cm or < 5 cm organic horizon unburned, respectively). Two or three pits were sampled at 1-cm depth intervals from 20 jack pine (Pinus banksiana) sites (one low severity and 19 high severity) and 31 black spruce (Picea mariana) sites (12 low severity and 19 high severity). Site-level charcoal stocks ranged from 50 to 5527 kg ha-1 with high within-site variability and lower stocks for the oldest sites. Depth distributions typically peaked around the organic-mineral interface, but some low-severity sites also had charcoal layers within the organic horizon. Means from 30 samples were 569 mg g-1 total C, 4.1 mg g-1 total N and 140 C/N (molar), with total C and C/N showing a trend of decline with time since fire, and total N showing an increase. Solid-state 13C CPMAS NMR spectra of nine samples showed high variability among the younger samples, but a trend to higher aromaticity for the older ones. A literature survey focusing on boreal forests similarly showed highly variable stocks and chemical properties of charcoal in organic horizon and upper mineral soil, with reduction of variance and lower stocks after several hundred years. This initial variation was also consistent with reports of highly variable temperatures and duration of charring in wildfires. Adding reports available for char production, and considering that most studies of char stocks and production are limited to the organic horizon (forest floor), suggests that initial production of charred material from boreal wildfires might be around 5-10 tonnes ha-1.

Depressed resilience of bluefin tuna in the western atlantic and age truncation.

PubMed

Secor, D H; Rooker, J R; Gahagan, B I; Siskey, M R; Wingate, R W

2015-04-01

Following intense overfishing in the 1970s, the western stock of Atlantic bluefin tuna (Thunnus thynnus) experienced a long period of depressed abundance, which has been attributed to failure of the population to periodically produce large numbers of juveniles, the western stock mixing with the more highly exploited eastern stock (fisheries in the Northeast Atlantic Ocean and Mediterranean Sea), and regime shift in the population's ecosystem resulting in lower replacement rates. To evaluate the presence of relatively strong years of juvenile production, we analyzed age structure from a recent sample of otoliths (ear stones) collected from the western stock (2011-2013, North Carolina, U.S.A., winter fishery). Mixing levels for the recent sample were analyzed using otolith stable isotopes to test whether age structure might be biased through immigration of eastern stock bluefin tuna. Age structure from historical samples collected from United States and Canadian fisheries (1975-1981) was compared with more recent samples (1996-2007) to examine whether demographic changes had occurred to the western stock that might have disrupted juvenile production. Relatively high juvenile production occurred in 2003, 2005, and 2006. Otolith stable isotope analysis showed that these recruitments were mostly of western stock origin. However, these high recruitments were >2-fold less than historical recruitment. We found substantial age truncation in the sampled fisheries. Half the historical sample was >20 years old (mean age = 20.1 [SD 3.7]; skewness = -0.3), whereas <5% of the recent sample was >20 years old (mean age = 13.4 [SD 3.8]; skewness = 1.3). Loss of age structure is consistent with changes in fishing selectivity and trends in the stock assessment used for management. We propose that fishing, as a forcing variable, brought about a threshold shift in the western stock toward lower biomass and production, a shift that emulates the regime shift hypothesis. An abbreviated reproductive life span compromised resilience by reducing the period over which adults spawn and thereby curtailing the stock's ability to sample year-to-year variability in conditions that favor offspring survival (i.e., storage effect). Because recruitment dynamics by the western stock exhibit threshold dynamics, returning it to a higher production state will entail greater reductions in exploitation rates. © 2014 Society for Conservation Biology.

Yield and dynamics of destabilized chub (Coregonus spp.) populations in Lakes Michigan and Huron, 1950-84

USGS Publications Warehouse

Brown, Edward H.; Argyle, Ray L.; Payne, N. Robert; Holey, Mark E.

1987-01-01

Deepwater ciscoes (Coregonus spp.) or 'chubs' of Lake Michigan far surpassed those of Lake Huron in yield, population density, and resilience following severe depletion in the 1960s and 1970s, when the bloater (C. hoyi) composed more than 90% of the stocks. The population decline of bloaters in recent decades was mainly attributed to exploitation, to the depression of chub recruitment (e.g. from inferred predation on early life stage) by nonendemic alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax), and to complications arising from extreme female predominance that was best documented for Lake Michigan. The various interactions between bloaters and the nonendemic species, which were intensified after the loss of large predators to sea lamprey (Petromyzon marinus), would help to explain why a stock-recruitment relation was not shown for the Lake Michigan bloater. We hypothesize that reproductive inefficiency caused by a shift to strong female predominance in the bloater depresses recruitment and thus helps to regulate abundance. However, the low resilience that sex imbalance seems to impart makes the stock unstable when exploited. It should therefore be exploited conservatively during such periods. Also, the sex ratio and its direction of change appear to be important qualifiers when surplus production is estimated from stock size.

Biotic and abiotic factors related to rainbow smelt recruitment in the Wisconsin waters of Lake Superior, 1978-1997

USGS Publications Warehouse

Hoff, Michael H.

2004-01-01

Lake Superior rainbow smelt (Osmerus mordax) recruitment to 12-13 months of age in the Wisconsin waters of Lake Superior varied by a factor of 9.3 during 1978-1997. Management agencies have sought models that accurately predict recruitment, but no satisfactory models had previously been developed. In this study, modeling was conducted to determine which factors best explained recruitment variability. The Ricker stock-recruitment model derived from only the paired stock and recruit data accounted for 63% of the variability in recruitment data. The functional relationship that accounted for the greatest amount of recruitment variation (81%) included rainbow smelt stock size, May rainfall, and bloater (Coregonus hoyi) biomass. Model results were interpreted to mean that recruitment was affected negatively by increased river flows from increased rainfall, and affected positively by the biomass of bloater, and those results were interpreted to mean that bloater mediated the effects of lake trout predation on rainbow smelt recruits. Model results were also interpreted to mean that stock size caused compensatory, density-dependent mortality on rainbow smelt recruits. Correlations observed here may be of value to managers seeking approaches to either enhance or control populations of this species, which is not indigenous to the Great Lakes.

Conditional Density Estimation with HMM Based Support Vector Machines

NASA Astrophysics Data System (ADS)

Hu, Fasheng; Liu, Zhenqiu; Jia, Chunxin; Chen, Dechang

Conditional density estimation is very important in financial engineer, risk management, and other engineering computing problem. However, most regression models have a latent assumption that the probability density is a Gaussian distribution, which is not necessarily true in many real life applications. In this paper, we give a framework to estimate or predict the conditional density mixture dynamically. Through combining the Input-Output HMM with SVM regression together and building a SVM model in each state of the HMM, we can estimate a conditional density mixture instead of a single gaussian. With each SVM in each node, this model can be applied for not only regression but classifications as well. We applied this model to denoise the ECG data. The proposed method has the potential to apply to other time series such as stock market return predictions.

50 CFR 300.211 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, with Annexes (WCPF... Conference on Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, the terms used in this... information. Commercial, with respect to commercial fishing, means fishing in which the fish harvested, either...

50 CFR 300.211 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, with Annexes (WCPF... Conference on Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, the terms used in this... information. Commercial, with respect to commercial fishing, means fishing in which the fish harvested, either...

Larvivorous fish for preventing malaria transmission.

PubMed

Walshe, Deirdre P; Garner, Paul; Adeel, Ahmed A; Pyke, Graham H; Burkot, Thomas R

2017-12-11

Adult female Anopheles mosquitoes can transmit Plasmodium parasites that cause malaria. Some fish species eat mosquito larvae and pupae. In disease control policy documents, the World Health Organization (WHO) includes biological control of malaria vectors by stocking ponds, rivers, and water collections near where people live with larvivorous fish to reduce Plasmodium parasite transmission. In the past, the Global Fund has financed larvivorous fish programmes in some countries, and, with increasing efforts in eradication of malaria, policymakers may return to this option. Therefore, we assessed the evidence base for larvivorous fish programmes in malaria control. To evaluate whether introducing larvivorous fish to anopheline larval habitats impacts Plasmodium parasite transmission. We also sought to summarize studies that evaluated whether introducing larvivorous fish influences the density and presence of Anopheles larvae and pupae in water sources. We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (Ovid); CABS Abstracts; LILACS; and the metaRegister of Controlled Trials (mRCT) up to 6 July 2017. We checked the reference lists of all studies identified by the search. We examined references listed in review articles and previously compiled bibliographies to look for eligible studies. Also we contacted researchers in the field and the authors of studies that met the inclusion criteria for additional information regarding potential studies for inclusion and ongoing studies. This is an update of a Cochrane Review published in 2013. Randomized controlled trials (RCTs) and non-RCTs, including controlled before-and-after studies, controlled time series, and controlled interrupted time series studies from malaria-endemic regions that introduced fish as a larvicide and reported on malaria in the community or the density of the adult anopheline population. In the absence of direct evidence of an effect on transmission, we performed a secondary analysis on studies that evaluated the effect of introducing larvivorous fish on the density or presence of immature anopheline mosquitoes (larvae and pupae forms) in water sources to determine whether this intervention has any potential that may justify further research in the control of malaria vectors. Two review authors independently screened each article by title and abstract, and examined potentially relevant studies for inclusion using an eligibility form. At least two review authors independently extracted data and assessed risk of bias of included studies. If relevant data were unclear or were not reported, we contacted the study authors for clarification. We presented data in tables, and we summarized studies that evaluated the effects of introducing fish on anopheline immature density or presence, or both. We used the GRADE approach to summarize the certainty of the evidence. We also examined whether the included studies reported any possible adverse impact of introducing larvivorous fish on non-target native species. We identified no studies that reported the effects of introducing larvivorous fish on the primary outcomes of this review: malaria infection in nearby communities, entomological inoculation rate, or on adult Anopheles density.For the secondary analysis, we examined the effects of introducing larvivorous fish on the density and presence of anopheline larvae and pupae in community water sources, and found 15 small studies with a follow-up period between 22 days and five years. These studies were undertaken in Sri Lanka (two studies), India (three studies), Ethiopia (one study), Kenya (two studies), Sudan (one study), Grande Comore Island (one study), Korea (two studies), Indonesia (one study), and Tajikistan (two studies). These studies were conducted in a variety of settings, including localized water bodies (such as wells, domestic water containers, fishponds, and pools (seven studies); riverbed pools below dams (two studies)); rice field plots (five studies); and water canals (two studies). All included studies were at high risk of bias. The research was insufficient to determine whether larvivorous fish reduce the density of Anopheles larvae and pupae (12 studies, unpooled data, very low certainty evidence). Some studies with high stocking levels of fish seemed to arrest the increase in immature anopheline populations, or to reduce the number of immature anopheline mosquitoes, compared with controls. However, this finding was not consistent, and in studies that showed a decrease in immature anopheline populations, the effect was not always consistently sustained. In contrast, some studies reported larvivorous fish reduced the number of water sources withAnopheles larvae and pupae (five studies, unpooled data, low certainty evidence).None of the included studies reported effects of larvivorous fish on local native fish populations or other species. We do not know whether introducing larvivorous fish reduces malaria transmission or the density of adult anopheline mosquito populations.In research studies that examined the effects on immature anopheline stages of introducing fish to potential malaria vector larval habitats, high stocking levels of fish may reduce the density or presence of immature anopheline mosquitoes in the short term. We do not know whether this translates into impact on malaria transmission. Our interpretation of the current evidence is that countries should not invest in fish stocking as a stand alone or supplementary larval control measure in any malaria transmission areas outside the context of research using carefully controlled field studies or quasi-experimental designs. Such research should examine the effects on native fish and other non-target species.

Assessing Soil Organic C Stability at the Continental Scale: An Analysis of Soil C and Radiocarbon Profiles Across the NEON Sites

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; McKnight, D. M.; Strahm, B. D.; Sanclements, M.

2017-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of physicochemical parameters on soil C stocks and turnover, and their relative importance in comparison to climatic variables. Soils were cored at NEON sites, sampled by genetic horizon, and density separated into light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon abundance was correlated with pH, with variance also grouping by dominate vegetation type. Soil order was also identified as an important proxy variable for C and radiocarbon abundance. Preliminary results suggest that both integrative proxies as well as physicochemical properties may be needed to account for variation in soil C abundance and stability at the continental scale.

SMS for Life: a pilot project to improve anti-malarial drug supply management in rural Tanzania using standard technology

PubMed Central

2010-01-01

Background Maintaining adequate supplies of anti-malarial medicines at the health facility level in rural sub-Saharan Africa is a major barrier to effective management of the disease. Lack of visibility of anti-malarial stock levels at the health facility level is an important contributor to this problem. Methods A 21-week pilot study, 'SMS for Life', was undertaken during 2009-2010 in three districts of rural Tanzania, involving 129 health facilities. Undertaken through a collaborative partnership of public and private institutions, SMS for Life used mobile telephones, SMS messages and electronic mapping technology to facilitate provision of comprehensive and accurate stock counts from all health facilities to each district management team on a weekly basis. The system covered stocks of the four different dosage packs of artemether-lumefantrine (AL) and quinine injectable. Results Stock count data was provided in 95% of cases, on average. A high response rate (≥ 93%) was maintained throughout the pilot. The error rate for composition of SMS responses averaged 7.5% throughout the study; almost all errors were corrected and messages re-sent. Data accuracy, based on surveillance visits to health facilities, was 94%. District stock reports were accessed on average once a day. The proportion of health facilities with no stock of one or more anti-malarial medicine (i.e. any of the four dosages of AL or quinine injectable) fell from 78% at week 1 to 26% at week 21. In Lindi Rural district, stock-outs were eliminated by week 8 with virtually no stock-outs thereafter. During the study, AL stocks increased by 64% and quinine stock increased 36% across the three districts. Conclusions The SMS for Life pilot provided visibility of anti-malarial stock levels to support more efficient stock management using simple and widely available SMS technology, via a public-private partnership model that worked highly effectively. The SMS for Life system has the potential to alleviate restricted availability of anti-malarial drugs or other medicines in rural or under-resourced areas. PMID:20979633

SMS for Life: a pilot project to improve anti-malarial drug supply management in rural Tanzania using standard technology.

PubMed

Barrington, Jim; Wereko-Brobby, Olympia; Ward, Peter; Mwafongo, Winfred; Kungulwe, Seif

2010-10-27

Maintaining adequate supplies of anti-malarial medicines at the health facility level in rural sub-Saharan Africa is a major barrier to effective management of the disease. Lack of visibility of anti-malarial stock levels at the health facility level is an important contributor to this problem. A 21-week pilot study, 'SMS for Life', was undertaken during 2009-2010 in three districts of rural Tanzania, involving 129 health facilities. Undertaken through a collaborative partnership of public and private institutions, SMS for Life used mobile telephones, SMS messages and electronic mapping technology to facilitate provision of comprehensive and accurate stock counts from all health facilities to each district management team on a weekly basis. The system covered stocks of the four different dosage packs of artemether-lumefantrine (AL) and quinine injectable. Stock count data was provided in 95% of cases, on average. A high response rate (≥ 93%) was maintained throughout the pilot. The error rate for composition of SMS responses averaged 7.5% throughout the study; almost all errors were corrected and messages re-sent. Data accuracy, based on surveillance visits to health facilities, was 94%. District stock reports were accessed on average once a day. The proportion of health facilities with no stock of one or more anti-malarial medicine (i.e. any of the four dosages of AL or quinine injectable) fell from 78% at week 1 to 26% at week 21. In Lindi Rural district, stock-outs were eliminated by week 8 with virtually no stock-outs thereafter. During the study, AL stocks increased by 64% and quinine stock increased 36% across the three districts. The SMS for Life pilot provided visibility of anti-malarial stock levels to support more efficient stock management using simple and widely available SMS technology, via a public-private partnership model that worked highly effectively. The SMS for Life system has the potential to alleviate restricted availability of anti-malarial drugs or other medicines in rural or under-resourced areas.

Carbon stocks of three secondary coniferous forests along an altitudinal gradient on Loess Plateau in inland China

PubMed Central

Liu, Ning; Nan, Hongwei

2018-01-01

Natural forests in inland China are generally distributed in montane area and secondary due to a semi-arid climate and past anthropogenic disturbances. However, quantification of carbon (C) stock in these forests and the role of altitude in determining C storage and its partition among ecosystem components are unclear. We sampled 54 stands of three secondary coniferous forests (Larix principis-rupprechtii (LP) forest, Picea meyerii (PM) forest and Pinus tabulaeformis (PT) forest) on Loess Plateau in an altitudinal range of 1200-2700m a.s.l. C stocks of tree layer, shrub layer, herb layer, coarse wood debris, forest floor and soil were estimated. We found these forests had relatively high total C stocks. Driven by both higher vegetation and soil C stocks, total C stocks of LP and PM forests in the high altitudinal range were 375.0 and 368.4 t C ha-1 respectively, significantly higher than that of PT forest in the low altitudinal range (230.2 t C ha-1). In addition, understory shrubs accounted for about 20% of total biomass in PT forest. The proportions of vegetation to total C stock were similar among in the three forests (below 45%), so were the proportions of soil C stock (over 54%). Necromass C stocks were also similar among these forests, but their proportions to total C stock were significantly lower in LP and PM forests (1.4% and 1.6%) than in PT forest (3.0%). Across forest types, vegetation biomass and soil C stock simultaneously increased with increasing altitude, causing fairly unchanged C partitioning among ecosystem components along the altitudinal gradient. Soil C stock also increased with altitude in LP and PT forests. Forest floor necromass decreased with increasing altitude across the three forests. Our results suggest the important role of the altitudinal gradient in C sequestration and floor necromass of these three forests in terms of alleviated water conditions and in soil C storage of LP and PM forests in terms of temperature change. PMID:29723254

Lipase pre-hydrolysis enhance anaerobic biodigestion of soap stock from an oil refining industry.

PubMed

Cherif, Slim; Aloui, Fathi; Carrière, Frédéric; Sayadi, Sami

2014-01-01

A novel alcalophilic Staphylococcus haemolyticus strain with the lipolytic activity was used to perform enzymatic hydrolysis pretreatment of soap stock: a lipid rich solid waste from an oil refining industry. The culture liquid of the selected bacteria and an enzymatic preparation obtained by precipitation with ammonium sulphate from a filtrate of the same culture liquid were used for enzymatic pretreatment. The hydrolysis was carried with different incubation concentrations (10, 20 and 30%) of soap stock and the pretreatment efficiency was verified by running comparative biodegradability tests (crude and treated lipid waste). All pretreated assays showed higher reaction rate compared to crude lipid waste, which was confirmed by the increased levels of biogas production. The pretreatment of solutions containing 10% emulsified soap stock was optimized for 24 h hydrolysis time, enabling high-biogaz formation (800 ml). The use of enzymatic pre-treatment seemed to be a very promising alternative for treating soap stock having high fat contents.

Simulating post-wildfire forest trajectories under alternative climate and management scenarios.

PubMed

Tarancón, Alicia Azpeleta; Fulé, Peter Z; Shive, Kristen L; Sieg, Carolyn H; Meador, Andrew Sánchez; Strom, Barbara

Post-fire predictions of forest recovery under future climate change and management actions are necessary for forest managers to make decisions about treatments. We applied the Climate-Forest Vegetation Simulator (Climate-FVS), a new version of a widely used forest management model, to compare alternative climate and management scenarios in a severely burned multispecies forest of Arizona, USA. The incorporation of seven combinations of General Circulation Models (GCM) and emissions scenarios altered long-term (100 years) predictions of future forest condition compared to a No Climate Change (NCC) scenario, which forecast a gradual increase to high levels of forest density and carbon stock. In contrast, emissions scenarios that included continued high greenhouse gas releases led to near-complete deforestation by 2111. GCM-emissions scenario combinations that were less severe reduced forest structure and carbon stock relative to NCC. Fuel reduction treatments that had been applied prior to the severe wildfire did have persistent effects, especially under NCC, but were overwhelmed by increasingly severe climate change. We tested six management strategies aimed at sustaining future forests: prescribed burning at 5, 10, or 20-year intervals, thinning 40% or 60% of stand basal area, and no treatment. Severe climate change led to deforestation under all management regimes, but important differences emerged under the moderate scenarios: treatments that included regular prescribed burning fostered low density, wildfire-resistant forests composed of the naturally dominant species, ponderosa pine. Non-fire treatments under moderate climate change were forecast to become dense and susceptible to severe wildfire, with a shift to dominance by sprouting species. Current U.S. forest management requires modeling of future scenarios but does not mandate consideration of climate change effects. However, this study showed substantial differences in model outputs depending on climate and management actions. Managers should incorporate climate change into the process of analyzing the environmental effects of alternative actions.

Quantifying edge effect extent and its impacts on carbon stocks across a degraded landscape in the Amazon using airborne lidar.

NASA Astrophysics Data System (ADS)

dos-Santos, M. N.; Keller, M.; Morton, D. C.; Longo, M.; Scaranello, M. A., Sr.; Pinagé, E. R.; Correa Pabon, R.

2017-12-01

Ongoing tropical forest degradation and forest fragmentation increases forest edge area. Forest edges experience hotter, drier, and windier conditions and greater exposure to fires compared to interior areas, which elevate rates of tree mortality. Previous studies have suggested that forests within 100 m from the edge may lose 36% of biomass during the first two decades following fragmentation, although such estimates are based on a limited number of experimental plots. Degraded forests behave differently from intact forests and quantifying edge effect extension in a degraded forest landscape is more challenging compared to experimental studies. To overcome these limitations, we used airborne lidar data to quantify changes in forest structure near 91 edges in a heavily degraded tropical forest in Paragominas Municipality, eastern Brazilian Amazon. Paragominas was a center of timber production in the 1990s. Today, the landscape is a mosaic of different agricultural uses, degraded, secondary and unmanaged forests. A total of 3000 ha of high density (mean density of 17.9 points/m2) lidar data were acquired in August/September 2013 and June/July 2014 over 30 transects (200 x 5000m), systematically distributed over the study area, using the Optech Orion M-200 laser scanning system. We adopted lidar-measured forest heights as the edge effect criteria and found that mean extent of edge effect was highly variable across degraded forests (150 ± 354m) and secondary forest fragments (265 ± 365m). We related the extent of forest edges to the historical disturbances identified in Landsat imagery since 1984. Contrary to previous studies, we found that carbon stocks along forest edges were not significantly lower than forest core biomass when edges were defined by previously estimated range of 100 and 300m. In frontier forests, ecological edge effect may be masked by the cumulative impact of historic forest degradation - an anthropogenic edge effect that extends beyond the scale of changes in forest microclimate from fragmentation.

The past and future of food stocks

NASA Astrophysics Data System (ADS)

Laio, Francesco; Ridolfi, Luca; D'Odorico, Paolo

2016-03-01

Human societies rely on food reserves and the importation of agricultural goods as means to cope with crop failures and associated food shortage. While food trade has been the subject of intensive investigations in recent years, food reserves remain poorly quantified. It is unclear how food stocks are changing and whether they are declining. In this study we use food stock records for 92 products to reconstruct 50 years of aggregated food reserves, expressed in caloric equivalent (kcal), at the regional and global scales. A detailed statistical analysis demonstrates that the overall regional and global per-capita food stocks are stationary, challenging a widespread impression that food reserves are shrinking. We develop a statistically-sound stochastic representation of stock dynamics and take the stock-halving probability as a measure of the natural variability of the process. We find that there is a 20% probability that the global per-capita stocks will be halved by 2050. There are, however, some strong regional differences: Western Europe and the region encompassing North Africa and the Middle East have smaller halving probabilities and smaller per-capita stocks, while North America and Oceania have greater halving probabilities and greater per-capita stocks than the global average. Africa exhibits low per-capita stocks and relatively high probability of stock halving by 2050, which reflects a state of higher food insecurity in this continent.

High-order fuzzy time-series based on multi-period adaptation model for forecasting stock markets

NASA Astrophysics Data System (ADS)

Chen, Tai-Liang; Cheng, Ching-Hsue; Teoh, Hia-Jong

2008-02-01

Stock investors usually make their short-term investment decisions according to recent stock information such as the late market news, technical analysis reports, and price fluctuations. To reflect these short-term factors which impact stock price, this paper proposes a comprehensive fuzzy time-series, which factors linear relationships between recent periods of stock prices and fuzzy logical relationships (nonlinear relationships) mined from time-series into forecasting processes. In empirical analysis, the TAIEX (Taiwan Stock Exchange Capitalization Weighted Stock Index) and HSI (Heng Seng Index) are employed as experimental datasets, and four recent fuzzy time-series models, Chen’s (1996), Yu’s (2005), Cheng’s (2006) and Chen’s (2007), are used as comparison models. Besides, to compare with conventional statistic method, the method of least squares is utilized to estimate the auto-regressive models of the testing periods within the databases. From analysis results, the performance comparisons indicate that the multi-period adaptation model, proposed in this paper, can effectively improve the forecasting performance of conventional fuzzy time-series models which only factor fuzzy logical relationships in forecasting processes. From the empirical study, the traditional statistic method and the proposed model both reveal that stock price patterns in the Taiwan stock and Hong Kong stock markets are short-term.

An analysis of genetic stock identification on a small geographical scale using microsatellite markers, and its application in the management of a mixed-stock fishery for Atlantic salmon Salmo salar in Ireland.

PubMed

Ensing, D; Crozier, W W; Boylan, P; O'Maoiléidigh, N; McGinnity, P

2013-06-01

A genetic stock identification (GSI) study was undertaken in a fishery for Atlantic salmon Salmo salar to determine the effects of restrictive fishery management measures on the stock composition of the fishery, and if accurate and precise stock composition estimates could be achieved on the small geographical scale where this fishery operates, using a suite of only seven microsatellite loci. The stock composition of the Foyle fishery was shown to comprise almost exclusively of Foyle origin fish in the 3 years after restrictive measures were introduced in 2007, compared to 85% the year before. This showed that the restrictive measures resulted in the Foyle fishery being transformed from a mixed-stock fishery to an almost exclusively single-stock fishery, and showed how GSI studies can guide and evaluate management decisions to successfully manage these fisheries. Highly accurate and precise stock composition estimates were achieved in this study, using both cBAYES and ONCOR genetic software packages. This suggests accurate and precise stock composition is possible even on small geographical scales. © 2013 AFBINI. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

Vertical patterns and controls of soil nutrients in alpine grassland: Implications for nutrient uptake.

PubMed

Tian, Liming; Zhao, Lin; Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Yue, Guangyang; Liu, Guimin; Chen, Hao

2017-12-31

Vertical patterns and determinants of soil nutrients are critical to understand nutrient cycling in high-altitude ecosystems; however, they remain poorly understood in the alpine grassland due to lack of systematic field observations. In this study, we examined vertical distributions of soil nutrients and their influencing factors within the upper 1m of soil, using data of 68 soil profiles surveyed in the alpine grassland of the eastern Qinghai-Tibet Plateau. Soil organic carbon (SOC) and total nitrogen (TN) stocks decreased with depth in both alpine meadow (AM) and alpine steppe (AS), but remain constant along the soil profile in alpine swamp meadow (ASM). Total phosphorus, Ca 2+ , and Mg 2+ stocks slightly increased with depth in ASM. K + stock decreased with depth, while Na + stock increased slightly with depth among different vegetation types; however, SO 4 2- and Cl - stocks remained relatively uniform throughout different depth intervals in the alpine grassland. Except for SOC and TN, soil nutrient stocks in the top 20cm soils were significantly lower in ASM compared to those in AM and AS. Correlation analyses showed that SOC and TN stocks in the alpine grassland positively correlated with vegetation coverage, soil moisture, clay content, and silt content, while they negatively related to sand content and soil pH. However, base cation stocks revealed contrary relationships with those environmental variables compared to SOC and TN stocks. These correlations varied between vegetation types. In addition, no significant relationship was detected between topographic factors and soil nutrients. Our findings suggest that plant cycling and soil moisture primarily control vertical distributions of soil nutrients (e.g. K) in the alpine grassland and highlight that vegetation types in high-altitude permafrost regions significantly affect soil nutrients. Copyright © 2017 Elsevier B.V. All rights reserved.

2009 Munitions Executive Summit

DTIC Science & Technology

2009-02-05

CURRENT OPERATIONS • Replenish stocks expended in operations • Build /Replenish War Reserve stocks • Modernize stocks in the process • Industrial Base...4 Steel-Consuming Markets Construction (40% - 45%) Appliances, Office Furniture (2.5%) Containers (4%) Industrial Equipment (15% - 18...Partnership - HPS for Bridges • U.S. Navy • FHWA • AISI Steel and Defense Industries Collaboration – High- Performance Steels 17 Major

Index Cohesive Force Analysis Reveals That the US Market Became Prone to Systemic Collapses Since 2002

PubMed Central

Kenett, Dror Y.; Shapira, Yoash; Madi, Asaf; Bransburg-Zabary, Sharron; Gur-Gershgoren, Gitit; Ben-Jacob, Eshel

2011-01-01

Background The 2007–2009 financial crisis, and its fallout, has strongly emphasized the need to define new ways and measures to study and assess the stock market dynamics. Methodology/Principal Findings The S&P500 dynamics during 4/1999–4/2010 is investigated in terms of the index cohesive force (ICF - the balance between the stock correlations and the partial correlations after subtraction of the index contribution), and the Eigenvalue entropy of the stock correlation matrices. We found a rapid market transition at the end of 2001 from a flexible state of low ICF into a stiff (nonflexible) state of high ICF that is prone to market systemic collapses. The stiff state is also marked by strong effect of the market index on the stock-stock correlations as well as bursts of high stock correlations reminiscence of epileptic brain activity. Conclusions/Significance The market dynamical states, stability and transition between economic states was studies using new quantitative measures. Doing so shed new light on the origin and nature of the current crisis. The new approach is likely to be applicable to other classes of complex systems from gene networks to the human brain. PMID:21556323