نتایج جستجو برای: wiener and simpson and richness indices
تعداد نتایج: 16837873 فیلتر نتایج به سال:
Aquatic macroinvertebrates, which play a significant role in the food chain of an ecosystem, are used in fresh water quality assessment to identify the environmental stress resulting from a variety of anthropogenic disturbances. Seasonal surveys of macroinvertebrate communities were conducted from April 2013 to March 2014 in Chhariganga oxbow lake of Nadia District of West Bengal, an eastern st...
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...
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...
This study was carried out to investigate the phytoplankton composition in Gorgan Bay. Water samples were collected from 11 selected sites in Golestan bay, monthly from March to February. Thirty five genus were identified among which Bacillariophyta was the dominate group with 17 genus, while the Euglenophyta had the minimum. Abundance and biomass of phytoplankton showed spatial and temporal va...
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...
0 Species richness typically increases with the number of individuals sampled\ although many ecological processes that in~uence species richness are also well known to depend on density of individuals[ We separated the e}ects of density on species richness that are due to sampling\ from those due to density!dependent ecological processes such as competition or predation\ by manipulating the den...
Choosing management strategies are influencing the vegetation characteristics and plant diversity in rangelands. We have studied the effects of three management treatments including overgrazing, exclusure, and exclusure with restoration operations on vegetation characteristics of plant cover, composition, and diversity in Kiasar Chardange summer rangelands. In each management treatment, three r...
silvicultural operation need to notice the plant species diversity in forest. to this study gomarlang district in marivan region, northern zagros forest was selected. selected 100 ha area because have similar physiography condition (north aspect and 1650 to 1800 m s.a.l. in study area 100 micro plots of 5m by 5 m (25 m2) including the species and the numbers of this species randomized-systemati...
Differences between plant biodiversity and grazing pastures grazed under improved management of rangeland habitat is of particular importance. The purpose of this study was to compare semi-steppe rangeland vegetation of Prdanan in the city of Piranshahr in the field under grazed and enclosed sites were considered. Sampled in both grazed and systematic random pastured five 40 meters trans...
this thesis is a study on insurance fraud in iran automobile insurance industry and explores the usage of expert linkage between un-supervised clustering and analytical hierarchy process(ahp), and renders the findings from applying these algorithms for automobile insurance claim fraud detection. the expert linkage determination objective function plan provides us with a way to determine whi...
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