نتایج جستجو برای: diversity indices
تعداد نتایج: 268614 فیلتر نتایج به سال:
Beta diversity is one of most important features in community ecology. Indices for pairwise comparison of beta diversity have been extensively developed, but the ones specifically designed for multiple-site comparison of beta diversity are still limited. Currently, by compiling all the available metrics based on the previous literature, plus some new metrics developed in the present report, we ...
Knowledge of the relationships between biotic components of rangeland ecosystem i.e. herbivores and plants is important for range managers. In order to study herbivorse grazing intensity on plant species diversity, an experiment was conductef using fuor grazing treatments in darrehshar rangelands, Ilam province in 2015. Plant species data were taken based on a randomized-systematic sampling met...
Recent attitude of vegetation assessors is using of new ecologic approaches to evaluate and analyse the complex rangeland ecosystems. Plant diversity is the most important indices to assess the ecological changes of rangelands. In order to survey of plant indices of rangelands, two exclosure areas (long-term and mid-term) and a grazing area in rangelands of Javaherdeh (Ramsar, Iran) were select...
Biodiversity is one of the important aspects of natursal systems which supports ecosystem functions. Therefore, the preservation of biodiversity is necessary for human well-being. The curreny study aimed to investigate changes of alpha and beta diversity and its components along the elevation gradient of five classes and to evaluate the effects of physical and chemical characteristics of soil o...
Numerical and parametrical indices are two of the most important and most widely used indices for assessing biodiversity in different societies. Nevertheless, their efficiency and selection in various ecosystems has always been one of the challenging issues of ecology. In this study, the numerical indices of diversity, richness and eveness, as well as abundance–ranking distribution models inclu...
Diversity is one of the most important issues in studies of vegetation ecology. This study was carried out in research forest of Tarbiat Modares University for surveying herbaceous and woody species diversity in relation to topographical factors (altitude, slope and aspect). For this purpose, 48 plots 400 m2 (20×20 m) were established in the region using selective sampling method. Then, the nam...
recent attitude of vegetation assessors is using of new ecologic approaches to evaluate and analyse the complex rangeland ecosystems. plant diversity is the most important indices to assess the ecological changes of rangelands. in order to survey of plant indices of rangelands, two exclosure areas (long-term and mid-term) and a grazing area in rangelands of javaherdeh (ramsar, iran) were select...
The aim of present study was comparison of plant diversity in managed and control compartments of Jamand district in Noshahr (Mazandaran province). Random-systematic sampling method with network dimension of 100×200 m was used to locate samples. Sampling plot area was 400 m2 to survey woody species and 100 m2 plots was set up to herbaceous species (in the center of main plots). At each sample p...
Background: Due to the importance of nutrition during pregnancy and its role in future generations' health, the study tried to determine dietary diversity and its relationship with newborns' anthropometric indices at birth. Methods: In this cross-sectional study, 400 pregnant women (28-40 weeks of pregnancy) whom were referred to the health centers in Zahedan were studied in 2016. To assess the...
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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