The Study of Woody Species Structure and Diversity in The Persian Oak (Quercus brantiiLindl) Site, Dashtak, Yasouj, Western Iran

This study was conducted to investigate the effect of aspect on woody species structure and diversity in the Persian oak (Quercus brantii Lindl.) site, Dashtak area, Kohkiloye and Boyer Ahamd province in western Iran. Measurements were carried out in 3 elevation classes range from 2200 m to 2400 m a.s.l. Then, three sampling plots with area of 2500- m2 were selected in each elevation class. In total, five tree species, including Quercus brantii, Crataegusdavisii, Pistacia atlantica. Subsp. mutica, Lonicera nummulariifolia and Amygdalus communisand three shrub species such as Cerasus microcarpa, Amygdalus orientalis and Daphne mucronata were identified in the study area. In regeneration and tree layers the sum of basal area and average of regeneration's density was higher in southwestern aspect and belonged to Quercus brantii. The results of diversity indices in the tree layer indicated that the average of H’ (Shannon-Wiener index), Evar (Smith-Wilson index) and species richness were higher in southwestern aspect than in the northeastern aspects. In addition, the values of all diversity, evenness and richness indices were significantly higher in southwestern aspect the in shrub and regeneration layers. In general, the results indicated that the diversity indices increased under favorable conditions of ecological, environmental and structural factors. Furthermore, livestock access and exploitation of local people should be restricted off, providing favorable conditions in order to increase the diversity of species.