نتایج جستجو برای: structural habitat variables

تعداد نتایج: 745422  

Journal: :Dong wu xue yan jiu = Zoological research 2010
Ji-Liang Xu Xiao-Hui Zhang Zheng-Wang Zhang Guang-Mei Zheng Xiang-Feng Ruan Ke-Yin Zhang Bo Xi

Reeves's Pheasant (Syrmaticus reevesii) is a threatened pheasant species endemic to China. The habitat use of territorial male birds was surveyed by the help of live decoys in a core area of Dongzhai National Nature Reserve. The breeding habitat selection of this pheasant was examined at two scales (115 m and 250 m scale, i.e. 4.15 hm(2 ) and 19.63 hm(2 ), respectively), including the character...

In this paper a league championship algorithm (LCA) is developed for structural optimization where the optimization variables are of discrete type and the set of the values possibly obtained by each variable is also given. LCA is a relatively new metaheuristic algorithm inspired from sport championship process. In LCA, each individual can choose to approach to or retreat from other individuals ...

2012
Jacob F. Schaefer Scott R. Clark Melvin L. Warren

Positive correlations between diversity and stability have been reported for a number of ecosystems and are thought to be caused by a stabilizing effect of differential species’ responses to environmental perturbation. Empirical field studies in which investigators tested for diversity–stability relationships are lacking for some taxonomic groups and typically have not included tests of the imp...

Journal: :Conservation biology : the journal of the Society for Conservation Biology 2009
Katherine R Greenwald H Lisle Gibbs Thomas A Waite

Amphibians worldwide are facing rapid declines due to habitat loss and fragmentation, disease, and other causes. Where habitat alteration is implicated, there is a need for spatially explicit conservation plans. Models built with geographic information systems (GIS) are frequently used to inform such planning. We explored the potential for using GIS models of functional landscape connectivity a...

2012
Inge Armbrecht

I analyzed a set of environmental and vegetation variables in order to characterize an intensification gradient for coffee production agroecosystems. I measured 14 habitat variables within 12 Colombian farms classified into four management systems at the Risaralda region of Colombia: Forests, Polygeneric Shaded coffee, Monogeneric Shaded coffee and Sun coffee plantations. The habitat variables ...

2012
Zhenhua Luo Songhua Tang Chunwang Li Hongxia Fang Huijian Hu Ji Yang Jingjing Ding Zhigang Jiang

BACKGROUND Explaining species richness patterns is a central issue in biogeography and macroecology. Several hypotheses have been proposed to explain the mechanisms driving biodiversity patterns, but the causes of species richness gradients remain unclear. In this study, we aimed to explain the impacts of energy, environmental stability, and habitat heterogeneity factors on variation of vertebr...

2011
Daniel C. Allen Caryn C. Vaughn

We examined how substrate and complex hydraulic variables limit the distribution of freshwater mussels. We sampled mussels and measured substrate and hydraulic variables (at low and high flows) at 6 sites in the Little River, Oklahoma. To test which variables were most limiting to mussel species richness and abundance, we evaluated univariate and multiple 95-, 90-, and 85-quantile regression mo...

2013
Anna McConville Bradley S. Law Michael J. Mahony

Habitat modelling and predictive mapping are important tools for conservation planning, particularly for lesser known species such as many insectivorous bats. However, the scale at which modelling is undertaken can affect the predictive accuracy and restrict the use of the model at different scales. We assessed the validity of existing regional-scale habitat models at a local-scale and contrast...

2010
Kirsten Sellheim John J. Stachowicz R. Cameron Coates

Native and exotic sessile invertebrates can act as habitat modifiers and influence the diversity and composition of associated epifaunal communities. Theory and empirical research predict that greater habitat structural complexity will generally result in higher abundance, richness, and diversity of epifaunal species. We evaluated the impact of a recently introduced, structurally complex bryozo...

2000
JOHN W. EDWARDS SUSAN C. LOEB DAVID C. GUYNN

-Multiple regression and use-availability analyses are two methods for examining habitat selection. Use-availability analysis is commonly used to evaluate macrohabitat selection whereas multiple regression analysis can be used to determine microhabitat selection. We compared these techniques using behavioral observations (n = 5534) and telemetry locations (n = 2089) of gray squirrels (Sciuru.s ...

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