نتایج جستجو برای: species diversity index
تعداد نتایج: 1072319 فیلتر نتایج به سال:
Plant Diversity conservation is a main objective in rangelandmanagement. Plant diversity is a suitable index for showing the changes ofvegetation in rangelands and has a high correlation with ecosystem parameters.Therefore, using this index it is possible to find the changes and manage theecosystem correctly. The current research was performed to determine the speciesdiversity in Fashandak rang...
in order to evaluate the weed diversity in forage crop fields such as alfalfa (medicago sativa l.), clover (trifolium sp.) and sainfoin (onobrychis spp.) in different provinces of iran, a study was conducted by using data from reports of plant protection organization, ministry of agriculture during 2008. after evaluation of weed species and definition of weed family, these species classified ba...
It has been paid less attention to effect of environmental factors on species richness and diversity indices in fragile ecosystems around Playa. Therefore this study was conducted to evaluate the effect of geographical directions and distance from Playa salt layer on the composition and species diversity in Sirjan Playa, Kerman Province, Iran. Determination of intervals 10, 1000 and 2000 mete...
Fish assemblage was investigated during the study of longitudinal profile of the Ehania River Basin in south-eastern Côte d’Ivoire. This area is subjected to intense human activities with many plantations (palm tree, banana, pineapple, coffee, rubber and cocoa). Samples were collected, with gillnets of different mesh sizes, through 6 sampling surveys during dry and rainy seasons from February 2...
forests are biologically diverse systems, representing some of the richest biological areas on earth. they offer a variety of habitats for plants, animals and micro-organisms. however, forest biodiversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. biodiversity is the variation of life forms within a given ecosystem, biome, or on t...
Population dynamics indices of parasites infected on cultured ornamental fishes according to the climatic changes in kurunagala district,Sri Lanka were estimated.Sample of gold fishes and koi carps which were harvested from mud ponds in ornamental fish breeding and traning center was examined for ecto parasites. Four population indices were calculated for each abundant parasite species and dive...
Fish assemblage was investigated during the study of longitudinal profile of the Ehania River Basin in south-eastern Côte d’Ivoire. This area is subjected to intense human activities with many plantations (palm tree, banana, pineapple, coffee, rubber and cocoa). Samples were collected, with gillnets of different mesh sizes, through 6 sampling surveys during dry and rainy seasons from February ...
Background and objectives: In order to properly manage rangeland ecosystems, it is necessary to study the relationship between ecological factors in nature such as elevation, climate and soil factors with vegetation and living organisms. In this regard, the present study was conducted to investigate the relationship between species diversity and environmental factors (Physical and chemical char...
in order to study the different levels of irrigation on diversity, density and compound of weed species in corn field, experiment was conducted at agricultural research station, ferdowsi university of mashhad during growing season of 2008-2009. the experiment was with four levels of irrigation (6130, 7290, 8800 and 12330 m3) and four levels of weed control (complete control, broad-leaves contro...
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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