A Floristic and Chorology Investigation of Oriental Arborvitae in Sourkesh Reserve (Fazel¬Abad¬-Golestan Province)

The oriental arborvitae habitat with an area of 223¬ha. is located on 20 km south of Fazel¬Abad, Golestan province. The lowest and highest of its height are 820 and 1680 m.a.s.l. The floristic-physiognomic investigation performed by walked-field procedure at 2nd seasonal sequence showed that flora of this region includes 173 plant species that belong to 147 genera and 65 families, of which 5 species are endemic to Iran. The families of Asteraceae (17 species), Papillionaceae and Rosaceae each one contained 13 species and Lamiaceae (10 species), Brassicaceae (9 species), Poaceae (8 species), Apiaceae, Boraginaceae and Caryophyllaceae each one contained 6 species along with Scoropholariaceae which contained 4 species, were the most important families, which include 53.2 percent of total species. According to Raunkiaer method, Hemicryptophytes (37%), Phanerophytes (24.8%), Therophytes (20.8%) and Cryptophytes (11%) were the most important structure groups of the local biological spectrum while according to Suzuki-Arakane method caespitose Hemicryptophytes (31.2%), Therophytes (20.8%), broad-leaved deciduous trees & shrubs (19%) and Rhizome-Geophytes (5.8%) were the most important life forms. The chorological study using Zohary method reveales that plants of Euro-Siberian region (24.3%), Irano-Turanian (23.1%), Hyrcanian province (11.6%) and Euro-Siberian and Irano-Turanian region (8.7%) are the most important chorological groups in the habitat and other chorotypes lie in the lower importance level.