Defining main environmental gradient in rangeland habitats using β diversity (Case study: Chaharbagh rangelands of Golestan Province)

Defining main environmental gradient in rangeland habitats using β diversity
(Case study: Chaharbagh rangelands of Golestan Province)

Abstract
Biodiversity is an important concept in ecology and vegetation management. Beta diversity is one of biodiversity levels. The aim of the study was to identify environmental gradient using beta diversity. The vegetation sampling was done using 536 randomly selected plots. Environmental unit maps were prepared by overlaying of basic maps (slope, aspect and elevation). The Gamma, Alfa and beta diversity in environmental units were calculated with Shannon index. The beta diversity variations showed that height variation is between "Ju. Ex, As. Go" and "Po bu, Co. ne" environment units (1.83). This gradient is main gradient called "Juniperus-Grass" gradient. of study area. According to the results, beta diversity index has good performance in showing variations between plant communities. Beta diversity can accurately be used to interpret diversity, similarity and dissimilarity between communities and rank main gradients.Key words: Beta Diversity, Gradient, Plant composition, Environmental units, Variations