Flora, life form and chorology of Box trees (Buxus hyrcana) habitats in forests of the Farim area of Sari

This study intends to present floristic-physiognomic investigation of Box trees (Buxus hyrcana) of the Farim area of Sari. All of species in the area were recorded by two methods field-walk and 60 releves with an area of 400 m2 in a systematic-selective design in two elevation classes, more and less than 1200 m above sea level implemented. Our results showed that the flora of this region includes 47 families, 67 genera, and 77 species. Phanerophytes (37.7%), Cryptophytes (32.5%) and Hemicryptophytes (24.7%) were the most important structure groups of the local biological spectrum according to Raunkiaer method, and also with increasing elevation, portions of Hemicryptophytes and Cryptophytes increased and decreased, respectively. Chorological studies showed that chorotype form Euro-Sibria was the most important phytochorion in two habitats. The correlation of environment variables with two first axes of DCA showed that elevation of sea level and dominance average (canopy percentage) of Box trees had decisive role on the vegetation composition and mean richness of species (Hill N0 index). Also, Jackknife estimation results confirmed that species richness in habitats with elevation more than 1200 m (75.8 species) had a higher level compared to habitats with elevation less than 1200 m (58.6 species) because of decreasing box trees dominance. Totally, the results of the present study not only confirmed the ecological capacity of Box trees in developing up to 1700 m in mountain forests of north Iran, but also the association of box trees with some plants of high regions with steep slope of north Hyrcanian forests such as: Acer mazandaranicum, Carpinus schuschaensis and Taxus baccata, can be introduced as two new syntaxa including Taxus baccata- Buxus hyrcana and Carpinus schuschaensis- Buxus hyrcana in Hyrcanian forests.