نتایج جستجو برای: richness
تعداد نتایج: 20745 فیلتر نتایج به سال:
Aim To forecast the responses of alpine flora to the expected upward shift of treeline ecotones due to climatic warming, we investigated species richness patterns of vascular plants at small spatial scales across elevational transects. Location Richness patterns were assessed at local scales along the elevational gradient in two undisturbed treeline ecotones and one disturbed treeline ecotone i...
We compare different null models for species richness patterns in the Nepalese Himalayas, the largest altitudinal gradient in the world. Species richness is estimated by interpolation of presences between the extreme recorded altitudinal ranges. The number of species in 100-m altitudinal bands increases steeply with altitude until 1,500 m above sea level. Between 1,500 and 2,500 m, little chang...
The interactive effects of changing biodiversity of consumers and their prey are poorly understood but are likely to be important under realistic scenarios of biodiversity loss and gain. We performed two factorial manipulations of macroalgal group (greens, reds, and browns) and herbivore species (amphipods, sea urchin, and fish) composition and richness in outdoor mesocosms simulating a subtida...
Functional diversity is the variability in the functional roles carried out by species within ecosystems. Changes in the environment can affect this component of biodiversity and can, in turn, affect different processes, including some ecosystem services. This study aimed to determine the effect of forest loss on species richness, abundance and functional diversity of Neotropical bats. To this ...
Hypothesis: Spatial variation in species richness is caused by increased maintenance metabolic costs that increase habitat overlap and decrease species richness. Organisms: Non-volant mammals in North America. Results: The latitudinal gradient in species richness could be completely explained by variation in maintenance metabolic costs. Additional spatial variation in species richness was posit...
In this paper we explore relationships between bird species richness and environmental factors in New York State, focusing particularly on how spatial scale, autocorrelation and nonstationarity affect these relationships. We used spatial statistics, Getis-Ord Gi*(d), to investigate how spatial scale affects the measurement of richness “hot-spots” and “cold-spots” (clusters of high and low speci...
Various models and estimation procedures for estimating the number of species in a community are reviewed under the following sampling schemes: sampling by continuous-type of efforts, sampling by individuals, and sampling by quadrats (or multiple occasions). Applications and relevant software are briefly reviewed.
Changes in producer diversity cause multiple changes in consumer communities through various mechanisms. However, past analyses investigating the relationship between plant diversity and arthropod consumers focused only on few aspects of arthropod diversity, e.g. species richness and abundance. Yet, shifts in understudied facets of arthropod diversity like relative abundances or species dominan...
Aim In this study, we examine patterns of local and regional ant species richness along three elevational gradients in an arid ecosystem. In addition, we test the hypothesis that changes in ant species richness with elevation are related to elevation-dependent changes in climate and available area. Location Spring Mountains, Nevada, U.S.A. Methods We used pitfall traps placed at each 100-m elev...
The diversity and richness of species are of important components to evaluate the health of ecologic system of rangelands. This research was conducted to investigate the biodiversity in riparian and neighboring areas via comparison of indices in Javaherdeh rangeland of Ramsar. Plot-transects was randomly used to estimate diversity, richness, dominance, and evenness indices in two regions. Multi...
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