Delineating changes in climatic variables and its impact on the Astragalus verus Olivier habitats in Isfahan Province

The genus of Astragalus accounts for 31.4 percent of area of Isfahan Province with Astragalus verus Olivier as a foremost species. This study aimed to investigate the contributing climatic variables to distribution of this species. Moreover, the trends of climatic variables and their influence on the species mortality. In doing so, 56 climatic variables relating to January, March, July, and the entire year were utilized. The Principal Component Analysis was employed to trim down the number of variables and their trends were analyzed using the Mann-Kendall test. The correlation analysis was ultimately used to investigate the association between climatic changes and mortality of Astragalus verus. Results showed that cooling temperature contributed most in the distribution of the species. The trend of temperature also indicated that mean temperature followed an upwards trend in most months of the year. Except Ardestan, Isfahan, Eastern Isfahan, and Kaboutar-Abad, annual precipitation declined but not significantly at the level of 1 and 5 percent. The dried up stands observed in Naeen region was estimated to be around 25 percent where the largest decreasing precipitation and increasing temperature was recorded. This estimate was only around 8 percent in Khansar and Chadegan whose increasing temperature and wind speed as well as decreasing precipitation were compensated by having a good growing potential.