Floristic and ecologic characteristics of Fazelabad oriental Arbor-vitae (Platycladus orientalis) habitat, Golestan province

Soorkesh protected area is one of the main habitat of important Tertiary relict species Platycladus orientalis in Golestan province. The altitude of this area ranges from 820 to 1680 m a. s. l. with an area of 223 ha. In a floristic survey of the area، 284 species from 212 genera and 63 families were identified. Asteraceae (42 spp.)، Poaceae (34 spp.) and Papilionaceae (24 spp.) were the largest families in terms of number of species. In the assessment of life form spectrum، the dominant life forms were hemicryptophytes (47. 5%)، followed by the therophytes (29. 2%)، phanerophytes (10. 9%)، cryptophytes (7. 4%) and chamaephytes (4. 9%). The flora was composed mostly of Euro-Siberian، Irano-Turanian، Mediterranean elements (24. 8%). A combined analyses of DCA indirect gradient analysis and Pearson correlation analysis of vegetation data and topographical data of 20 relevés of 100 m2 indicated that altitude، slope inclination and heat index affect floristic composition of the area.