Investigating the Effects of Soil Factors on Biodiversity in Plant Communities of Karvan Rangeland (Case Study: Isfahan Province, Iran)

Abstract. Understanding the plant species diversity could be used as an important indicator applied for the natural areas management. The aim of this study was to investigate the relationships between soil characterizes with distribution and diversity of plant in vegetation types in Karvan district (located in west of Isfahan province). For this purpose, three vegetation types were selected as follows: Scariola orientalis-Astragalus gossypinus (Sc.or-As.go), Hordeum fragile-Astragalus gossypinus (Ho.fr-As.go) and Cousinia bachtiarica-Astragalus gossypinus (Cu.ba-As.go). Then, four transects random sampling - systematic bias to the general and lateral slope of the region in each vegetation type were placed and the name and other characterize of the plants were recorded by 90 of randomly quadrate one m2, also the soil samples of the start and end of each transect from two different depths (0-20 and 20-75 cm) of soil were taken. Soil samples were analyzed and the physicochemical factors were measured. Diversity indices such as Menhinick, Margalef and Fisher alpha were analyzed by VMSP software and soil data were analyzed by PC-ORD software. The results of numerical indices showed a different diversity index in vegetation types and there were significant correlation between some soil properties and diversity index. It was concluded that the Sc.or-As.go type had the highest diversity in comparison with the other vegetation types (Ho.fr-As.go and Cu.ba-As.go). Finally soil properties such as organic matter, clay and soil depth had positive and the amount of lime and gypsum had negative correlation with species diversity.