A floristic study of Chahchaheh Pistacia forest, NE Iran

Chahchaheh pistacia forest is located in northeastern of Khorassan-e Razavi province, between 36º35′ to 36º36′ northern latitudes and 60º21′ to 60º23′ eastern longitudes, with an area around 3000 hectares. The altitude of the area ranges from 450 to 1000 m, the mean annual rainfall is 254.8 mm and the mean annual temperature is 17.9ºC. Based on collection of about 1536 specimens, a total number of 248 plant species and subspecies were identified from this area belonging to 159 genera and 36 plant families. The largest families were Asteraceae, with 47 species, Poaceae, with 30 species, Fabaceae, with 24 species, and Brassicaceae, with 23 species. The most diverse genera included Astragalus, Cousinia (8 species), and Alyssum, Bromus, Polygonum, Centaurea (5 species). Therophytes, constituting 55.6% of the biological types, were dominant, followed by hemicryptophytes and chamephytes with 26.4% and 9.2%, respectively. From the standpoint of vegetation types, 56.4% of the chorotypes belong to Irano-Turanian vegetative elements and the rest were related to one, two, three or various other vegetation regions or had a global distribution. Among the distributed species, six species were endemic to Iran which composed about 2.41% of the total number of species and 0.33% of the total number of Iran endemic species.