Browsing by Subject "COMMUNITIES"

Now showing 1 - 6 of 6
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    A novel approach to assess livestock management effects on biodiversity of drylands
    (Ecological Indicators, 2015-01-01) Chillo, V; Ojeda, RA; Anand, M; Reynolds, JF
    In drylands livestock grazing is the main production activity, but overgrazing due to mismanagement is a major cause of biodiversity loss. Continuous grazing around water sources generates a radial gradient of grazing intensity called the piosphere. The ecological sustainability of this system is questionable and alternative management needs to be evaluated. We apply simple indicators of species response to grazing gradients, and we propose a novel methodological approach to compare community response to grazing gradients (double reciprocal analysis). We assessed degradation gradients of biodiversity under different management strategies in semiarid rangelands of the Monte desert (Argentina) by analyzing changes in vegetation, ants and small mammal richness and diversity, and variation due to seasonality. At the species level, we determined the trend in abundance of each species along the gradient, and the potential cross-taxa surrogacy. At the community level, the new methodological consists of assessing the magnitude of biodiversity degradation along different piospheres by comparing the slopes of linear functions obtained by the double reciprocal analysis. We found that most species showed a decreasing trend along the gradient under continuous grazing; while under rotational grazing fewer species showed a decreasing trend, and a neutral trend (no change in the abundance along the gradient of grazing intensity) was the most common. We found that vegetation cannot be used as a surrogacy taxon of animal response. Moreover, weak cross-taxa surrogacy was found only for animal assemblages during the wet season. The double reciprocal analysis allowed for comparison of multi-taxa response under different seasons and management types. By its application, we found that constrains in precipitation interacted with disturbance by increasing the negative effect of grazing on vegetation, but not on animal assemblages. Continuous grazing causes biodiversity loss in all situations. Rotational grazing prevents the occurrence of vegetation degradation and maintains higher levels of animal diversity, acting as an opportunity for biodiversity conservation under current scenarios of land use extensification. Our approach highlights the importance of considering multi-taxa and intrinsic variability in the analysis, and should be of value to managers concerned with biodiversity conservation.
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    Associations Between Nutrition, Gut Microbiome, and Health in A Novel Nonhuman Primate Model.
    (Scientific reports, 2018-07-24) Clayton, Jonathan B; Al-Ghalith, Gabriel A; Long, Ha Thang; Tuan, Bui Van; Cabana, Francis; Huang, Hu; Vangay, Pajau; Ward, Tonya; Minh, Vo Van; Tam, Nguyen Ai; Dat, Nguyen Tat; Travis, Dominic A; Murtaugh, Michael P; Covert, Herbert; Glander, Kenneth E; Nadler, Tilo; Toddes, Barbara; Sha, John CM; Singer, Randy; Knights, Dan; Johnson, Timothy J
    Red-shanked doucs (Pygathrix nemaeus) are endangered, foregut-fermenting colobine primates which are difficult to maintain in captivity. There are critical gaps in our understanding of their natural lifestyle, including dietary habits such as consumption of leaves, unripe fruit, flowers, seeds, and other plant parts. There is also a lack of understanding of enteric adaptations, including their unique microflora. To address these knowledge gaps, we used the douc as a model to study relationships between gastrointestinal microbial community structure and lifestyle. We analyzed published fecal samples as well as detailed dietary history from doucs with four distinct lifestyles (wild, semi-wild, semi-captive, and captive) and determined gastrointestinal bacterial microbiome composition using 16S rRNA sequencing. A clear gradient of microbiome composition was revealed along an axis of natural lifestyle disruption, including significant associations with diet, biodiversity, and microbial function. We also identified potential microbial biomarkers of douc dysbiosis, including Bacteroides and Prevotella, which may be related to health. Our results suggest a gradient-like shift in captivity causes an attendant shift to severe gut dysbiosis, thereby resulting in gastrointestinal issues.
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    Evaluating the best available social science for natural resource management decision-making
    (Environmental Science and Policy, 2017-07-01) Charnley, S; Carothers, C; Satterfield, T; Levine, A; Poe, MR; Norman, K; Donatuto, J; Breslow, SJ; Mascia, MB; Levin, PS; Basurto, X; Hicks, CC; García-Quijano, C; St. Martin, K
    © 2017 Increasing recognition of the human dimensions of natural resource management issues, and of social and ecological sustainability and resilience as being inter-related, highlights the importance of applying social science to natural resource management decision-making. Moreover, a number of laws and regulations require natural resource management agencies to consider the “best available science” (BAS) when making decisions, including social science. Yet rarely do these laws and regulations define or identify standards for BAS, and those who have tried to fill the gap have done so from the standpoint of best available natural science. This paper proposes evaluative criteria for best available social science (BASS), explaining why a broader set of criteria than those used for natural science is needed. Although the natural and social sciences share many of the same evaluative criteria for BAS, they also exhibit some differences, especially where qualitative social science is concerned. Thus we argue that the evaluative criteria for BAS should expand to include those associated with diverse social science disciplines, particularly the qualitative social sciences. We provide one example from the USA of how a federal agency − the U.S. Forest Service − has attempted to incorporate BASS in responding to its BAS mandate associated with the national forest planning process, drawing on different types of scientific information and in light of these criteria. Greater attention to including BASS in natural resource management decision-making can contribute to better, more equitable, and more defensible management decisions and policies.
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    Habitat fragmentation and biodiversity conservation: key findings and future challenges
    (Landscape Ecology, 2016-02-01) Wilson, MC; Chen, XY; Corlett, RT; Didham, RK; Ding, P; Holt, RD; Holyoak, M; Hu, G; Hughes, AC; Jiang, L; Laurance, WF; Liu, J; Pimm, SL; Robinson, SK; Russo, SE; Si, X; Wilcove, DS; Wu, J; Yu, M
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    Jim Crow, Ethnic Enclaves, and Status Attainment: Occupational Mobility among U.S. Blacks, 1880-1940
    (American Journal of Sociology, 2018) Ruef, M; Grigoryeva, Angelina
    Demographic and ecological theories yieldmixed evidence as to whether ethnic enclaves are a benefit or a hindrance to the status attainment of residents and entrepreneurs. This article provides one possible theoretical resolution by separating the positive effects that may emanate among co-ethnic neighbors from the negative effects that may resultwith the concentration of racial or ethnic groups. The theory is tested by analyzing occupational wage attainment and entrepreneurship among African-Americans between 1880 and 1940, a historical context in which Jim Crow laws imposed segregation exogenously. Drawing on crosssectional and panel census data for representative samples of blacks in theUnited States, the results suggest consistent upward occupational mobilityamong residents with same-race neighbors, accompanied with downward mobility among residents who are concentrated in larger racialized enclaves. Both patterns are also observed in the distribution of entrepreneurial activity among blacks during the Jim Crow era.
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    Scientific rationale and international obligations for protection of active hydrothermal vent ecosystems from deep-sea mining
    (MARINE POLICY, 2018-04-01) Van Dover, Cindy; Arnaud-Haond, S; Gianni, M; Helmreich, S; Huber, JA; Jaeckel, AL; Metaxas, A; Pendleton, LH; Petersen, S; Ramirez-Llodra, E; Steinberg, PE; Tunnicliffe, V; Yamamoto, H