Studing the Acclimation of Bromus Tomentellus in Esfahan Province

Bromus tomentellus is one of the drought resistant species that has a relatively well developed in Esfahan province، therefore، in the present study some of the important factors that influence the distribution of this species are studied. In this study، 17 climatic variables from 43 synoptic and climatology stations were selected within and adjacent areas of Esfahan province which the stations managed by Weather Organization of Iran. To reduce the number of variables and determining effective factor was used factor analysis using by principal components analysis with varimax rotation، then the average factor scores in the habitat of this species and the areas without it were calculated and the spatial distribution of the factor scores were plotted in Surfer ver8. The results of the factor analysis identified three factors of precipitation، temperature and wind and sunshine hours. These factors are included 69. 70%، 11. 98% and 10. 14%، respectively and 92% of the total variance of the data. Also، the results showed that both precipitation and cooling temperature are the important factors to presence of these species as dominant and following species and wind and sunshine hours has the least effect on it. Generally، the climate vegetative of Bromus tomentellus can be named in Isfahan province، semi-steppe vegetation region in Fereidan، Freydoonshahr، Semirom، Golpayegan، Khonsar، Meimeh up around the Shahreza and alpine steppe of Natanz and Kashan.