نتایج جستجو برای: diversity indices
تعداد نتایج: 268614 فیلتر نتایج به سال:
Biodiversity is one of the important concepts in ecology and vegetation management, and plays an important role in the health, production, and evaluation of ecosystems. Species diversity is a major part of biodiversity and one of the most important parameters of ecosystem changes. In this research, the data of the rangeland evaluation different climate zones of Isfahan province were used in fiv...
knowledge about spatial soil variation in terms of measured pedodiversity offers the possibility to estimate the quality and variance within a soil map. diversity indices and abundance distribution models are statistical tools which ecologists have applied for decades for analyzing the intrinsic regularities of various ecological entities. in this study relationships between soils evolution, la...
Exclosure is considered as a management method to improve vegetation. This study aimed to evaluate the effects of exclosure on species diversity in Zayanderod dam station in Chadegan, Isfahan. The study area was stratified based on the various management types and slope directions, and samples were collected randomly in each layer. Four perpendicular transects, 500m in length were established a...
Biodiversity plays a crucial role in stability and productivity of natural ecosystem. The main goal of this research was to classify ecological groups in steppe rangeland and investigate their relationships with plant diversity indices. Therefore, fifty different Land Unit Tracts (LUT) were identified in Khod-Neuk basin, Yazd province, Iran, in 2010. Vegetation and soil samples were taken in th...
Numerical indices of diversity, in their entirety, do not provide a complete description of distribution and richness of species. Therefore, parametric indices should be also considered in studying of plant communities. In this regard, the indices of species richness, evenness and diversity related to the ecological sites of Cher mountainous rangelands of Urmia were calculated. The diversity pr...
Trees are the most important biological elements of forest ecosystems. The variability of the tree species composition inhabiting in the Oriental beech forest, not only forms different forest types but also has a remarkable impact on the species diversity of forest floor plants, due to the existence of trees in the overstory layer. In this research, forest types of an an Oriental beech were ide...
Entropy measures of probability distributions are widely used measures in ecology, biology, genetics, and in other fields, to quantify species diversity of a community. Unfortunately, entropy–based diversity indices, or diversity indices for short, suffer from three problems. First, when computing the diversity for samples withdrawn from communities with different structures, diversity indices ...
This study evaluated the relationship between the indices known as the Reef Health Index (RHI) and two-dimensional Coral Health Index (2D-CHI) and different representative metrics of biological, ecological and functional diversity of fish and corals in 101 reef sites located across seven zones in the western Caribbean Sea. Species richness and average taxonomic distinctness were used to asses b...
Biodiversity, a multidimensional property of natural systems, is difficult to quantify partly because of the multitude of indices proposed for this purpose. Indices aim to describe general properties of communities that allow us to compare different regions, taxa, and trophic levels. Therefore, they are of fundamental importance for environmental monitoring and conservation, although there is n...
One of the main objectives of ecosystem management is to preserve the speciesdiversity. Many researchers regard higher species diversity as the stability of ecologicalsystems. The aim of this study is to investigate the stability and relationships betweentopographical factors with diversity indices in Ghorkhud mountainous rangeland innorthern Khorasan province, Iran. For data sampling (2012), l...
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