نتایج جستجو برای: richness
تعداد نتایج: 20745 فیلتر نتایج به سال:
Methods We digitized lizard distribution data to generate gridded maps of species richness and b-diversity. Using similar maps for amphibians, mammals and birds, we explored the relationship between species richness and temperature, actual evapotranspiration, elevation and local elevation range. We used spatial eigenvector filtering and geographically weighted regression to explore geographical...
Periphytic algae are important components of aquatic ecosystems. However, the factors driving periphyton species richness variation remain largely unexplored. Here, we used data from a subtropical floodplain (Upper Paraná River floodplain, Brazil) to quantify the influence of environmental variables (total suspended matter, temperature, conductivity, nutrient concentrations, hydrology, phytopla...
Evaluation of plant richness and diversity is important in rangeland ecosystems because biological control, conservation of genetic resources and the control of natural ecosystems are possible by identifying diversity. One of the factors affecting the richness and diversity is animals' utilization of the vegetation. Therefore, this research was done to study the plant richness and diversity res...
Livestock grazing is a common human-induced activity with direct and indirect effects even on the ecosystems of protected areas. The present study analyzed the effects of different grazing management methods on species diversity and richness in the steppe rangelands of Saveh, Iran. Data were collected from sixty 2×2 m plots within the areas of three, four-years protected range management projec...
This study aimed to investigate the effect of canopy trees and shrubs: Pistacia atlantica, Amygdalus scoparia, Amygdalus eburnean on the species diversity and richness of soil seed bank. Ten individuals of each species were selected and one quadrate was established in and outside of crown canopy of each species. In each plot, soil samples were collected from 0-5 and 5-10 cm depths. GLM was appl...
To achieve sustainable development as well as the conservation of natural ecosystems and their biodiversity, it is necessary to study ecological foctors and their impacts on plant species diversity. The Khorramabad-Andimeshk highway was selected in the current study to investigate the diversity of the family Brassicaceae. The length of this highway is 100 km and its height ranged from 420 to 17...
Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?
Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance b...
Testing Media Richness Theory in the New Media: The Effects of Cues, Feedback, and Task Equivocality
Media richness theory argues that performance improves when team members use “richer” media for equivocal tasks. This experiment studied the effects of media richness on decision making in two-person teams using “new media” (i.e., computer-mediated and video communication). Media richness was varied based on multiplicity of cues and immediacy of feedback. Subjects perceived differences in richn...
Many researchers hypothesize that plant richness declines at high soil fertility (and high productivity) due to light limitation. We tested this hypothesis in an old-field by independently manipulating fertilization and light levels via shade cloth (decreased light), vegetation tie-backs (increased light) and vegetation clipping (increased light). Droughts occurred during two of the four years ...
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