The relation between Vegetation diversity and some of environmentally variables in Nodoushan steppe rangelands, Yazd

In this research, the effects of important environmental variables on vegetation diversity were determined in Nodoushan-Yazd. For this purpose, 46 various land unit tracts (LUT) were studied. To collect vegetation data, the number and optimum size of sampling plots were determined using the statistical and minimal area methods, respectively. For each sampled unit, one composite soil sample was collected according to plant root depth. Soil properties included: gravel, texture, saturation percentage (S.P), calcium carbonate, pH, EC, soluble ions (Na+, Mg2+ and Ca2+) and S.A.R.The study of diversity indices was performed based on species canopy cover, the presence or absence of species and the use of three diversity indices (richness, Shannon-Wiener and Simpson). Then, the relationship between environmental variables and biodiversity indices was investigated using RDA ordination. According to the obtained results, altitude had the most impact on vegetation diversity. The species diversity indices were also significantly correlated with some of the soil variables, including Na, T.N.V, saturation percentage (S.P) and soil texture. The trend of changes in species diversity in the study area had significant correlation with the type of geological formation.