The most abundant species of the Astragalus genus along the altitude gradient of Iran

Determining the distribution range and habitat conditions of indicator species of plant communities in rangeland ecosystems is the basic information needed for these ecosystems' management. Different species of the Astragalus genus have diverse functions in natural ecosystems. Therefore, in this article, the distribution area of the Astragalus species in Iran and their relationship with the altitude factor were evaluated. According to the obtained results, the total area of Iran's Astragalus habitats in those rangelands where Astragalus species are present in the main composition of the plant types is higher than 20.94 million hectares (13% of the country's area). The most area of Astragalus habitat and the most species richness of the Astragalus genus are located at 1000 to 3000 m.s.l. A. fasciculifolius, A. arbusculinus, A. spinosus, and A. squarrosus arethe most frequent of the Astragalus genus at altitudes of less than 1000 meters. A. fasciculifolius, A. microcephalus, and A. gossypinus are the most frequent species of the Astragalus genus at altitudes of 1000 to 2000 meters. A. adscendens, A. microcephalus, A. susianus, and A. gossypinus are the most frequent species of the Astragalus genus at altitudes of 2000 to 3000 meters.  A. adscendens, A. gossypinus, and A. microcephalus are the most frequent of the Astragalus genus in areas with altitudes of more than 3000 meters.