LAUSR

In order to identify factors affecting the distribution of Anabasis aphylla in rangelands of Iran, 132 climatic parameters which contributed to the species distribution (based on the ecological conditions of the study area) were selected. Factor analysis was then applied to determine the most important factors affecting species distribution. In the next stage, the spatial distribution map of An. aphylla throughout Iran was prepared. According to the results of factor analysis, ten factors with Eigenvalues greater than one explained 92.96% of the total variance. These factors were temperature below zero, winter rainfall, summer rainfall, wind, sunlight, warm season dust, rainfall in fall, thunderstorms, relative humidity in September, and cloudy days in winter and explained 34.34, 9.71, 9.69, 8.85, 5.99, 5.35, 4.97, 4.78, 4.73, and 4.51% of the total variance, respectively. Moreover, six vegetation types containing An. aphylla were identified throughout the country. These types were distributed in the central areas of Iran and also in patches within the southeastern parts of the country. The results showed that in addition to the nine above climatic factors, soil variables particularly salinity influence establishing the vegetation types in their distribution areas and the vegetation types are located in low to relatively high salinity, and soils with these salinity levels (low to relatively high salinity) are suitable for these types of plants.