Effects of Altitude and Soil Properties on Alpha and Beta Diversity in Plour Rangelands of Mazandaran

Biodiversity is one of the important aspects of natursal systems which supports ecosystem functions. Therefore, the preservation of biodiversity is necessary for human well-being. The curreny study aimed to investigate changes of alpha and beta diversity and its components along the elevation gradient of five classes and to evaluate the effects of physical and chemical characteristics of soil on these diversity indices. In each elevation class, 20 soil samples and a total of 100 samples were taken and the relationship between physical and chemical characteristics of soil with diversity indices was examined. The number of species was recorded at 100 plots and the alpha and beta diversity indices were calculated at two spatial scales (i.e., plot and transect) using R software. Based on the results, the lowest amount of alpha diversity across plots (12.47 ± 1.03) and transects (24.15 ± 1.06) were observed at the elevation class of > 3200 m, while, the lowest amount of beta diversity in plots (11 ± 0.78) and transects (18 ± 0.44) were observed in class of < 2600 m. In all altitude classes, more than 90% of the variation in beta diversity was explained by the species turnover component and the nested pattern component was responsible for a very small part of beta diversity. Environmental factors were explanined only 11% of the changes in alpha diversity and 30% of the beta diversity. This result indicates the high complexity of the environment and plant communities and clearly shows that using a few environmental variables cannot reveal all the changes in plant composition.