نتایج جستجو برای: species evenness
تعداد نتایج: 548668 فیلتر نتایج به سال:
this research was conducted in two protect and destroy region in the middle zagros, in illam province. in order to identification of ecological species group and evaluate density of regeneration, effect of many factors such as protection, vegetation, physiographic factors, physical and chemical properties of soil in study locations were studied. to achieve these purpose number of 54 plots using...
gradual decrease of biodiversity related to the rapid industrialization and urbanization is stimulating the fundamental research towards a better understanding of the relationships between biodiversity and ecosystem functioning. present study emphasizes the nature and status of floral diversity in the vicinity of integrated industrial estate-pantnagar, uttarakhand, india (iie-pantnagar).three m...
Evenness is a key measure of community structure. Here, we examine the relationship between evenness and size-abundance distributions for both individuals and species using data gathered from Amazonian fish assemblages. We show that evenness increases as the fraction of numerically abundant species in larger body-size classes rises. As any processes that enable larger bodied species to increase...
Biodiversity is declining worldwide from reductions in both species richness and evenness. Field experiments have shown that primary productivity is often reduced when richness of plant species is lowered. However, experiments testing richness effects have used evenness levels that are much higher than normally encountered in plant communities and have been based on the assumption that species ...
In nature, plant biomass is not evenly distributed across species, and naturally uncommon species may differ from common species in the probability of loss from the community. Understanding relationships between evenness and productivity is therefore critical to understanding changes in ecosystem functioning as species are lost from communities. We examined data from a large multi-site grasslan...
Healthy ecosystems include many species (high richness) with similar abundances (high evenness). Thus, both aspects of biodiversity are worthy of conservation. Simultaneously conserving richness and evenness might be difficult, however, if, for example, the restoration of previously absent species to low densities brings a cost in reduced evenness. Using meta-analysis, we searched for benefits ...
Species richness and evenness are the two major components of biodiversity, but the way in which they are interrelated is a subject of contention. We found a negative relationship between the two variables for bird communities at 92 woodland sites across Australia and sought an explanation. Actual evapotranspiration (AET) was by far the best predictor of species richness. When AET was controlle...
rangeland ploughing and cultivation using dry land farming crops may be amajor reason for the destruction of natural resources in the semiarid and sub-humid regionswhich may significantly change the composition and reduce the stability of the affectedcommunities. in present research, an abandoned ploughed site was compared with a nearbyreference site in the semiarid rangelands of baharkish, quc...
Information about gaps and their sizes distribution is useful for protecting herbaceous diversity. This study was conducted to investigate the effect of gap size on herbaceous species diversity in oriental beech (Fagus orientalis Lipsky.) stand in Asalem, Guilan province. For this study, fifteen gaps in small, medium, and large sizes were randomly selected. Then, herbaceous species were ident...
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