Physiographic factors influencing the vegetation biodiversity in Pishkooh-Yazd

The present study addressed the effect of physiographic attributes on Biodiversity indices of vegetation (diversity، richness and evenness) in Rangelands of Pishkooh-Yazd. The study area was located in latitude 31° 45 '' -32° 3 '' N; longitude 53° 28 '' -53° 47 '' E. Sampling sites were selected based on Land stratification method that allowed the study area to be subdivided into Land Unit Tracts (LUT)، according to specified criteria including landform attributes (slope، aspect and altitude) and substrate type. Vegetation samplings were performed using randomized-systematic method. The size of sampling plots was selected based on minimal area method. Totally 45 plant species were recognized in this area. The results showed that elevation A. S. L. had significant effect on Biodiversity indices and mean elevation of 2300-2600 meters A. S. L. had higher diversity، richness and evenness than other elevation classes. Slope also affected diversity and richness significantly and high slopes (30-60%) had the highest diversity and richness. The aspect had no significant effect on biodiversity indices.