Impact of environmental factors on distribution and some quantitative characteristics of Manna Oak (Quercus brantii Lindl.) in Fars province

Tree species distribution in different ecological zones depends on their ecological demands including the physical and chemical properties of soils as well as different aspects and altitudes. In this research, several ecological characteristics of Quercus brantii were studied. This species is distributed in three altitudes of:1000-1500,1500-2000 and higher than 2000 m.a.s.l. Fifty two site samples, each covering 500m2, were selected in the basis of several parameters including aspect, land form and elevation classes. Different variables such as species, diameter at breast height (dbh), tree height, trunk height, crown cover, origin (standard or coppice), age class, number of sprouts, accompanying species and forest type were measured or recorded in each sample plot. Moreover, a soil profile was dug in each sample plot. Results showed that natural distribution of Quercus brantii varies from 1050 to 2550 m.a.s.l in all land forms. The pH of the studied sites varied between 7.5 and 8.1, and the soil texture varied from clay, clay- loam to loam. The most important limiting factors in the soil of the studied area were the texture and organic matter, whereas the soil moisture was an important factor for the presence of this species. The eastern slopes had the highest density, while the flat area showed the highest crown cover and dbh. The average crown area of each tree in seed origin and coppice origin plots were 16.61 m2 and 15.71m2, respectively. The mean dbh was 20.2cm and the average number of sprouts per tree was 5.9. The mean total tree height was 6.1m in seed origin and 5.59m in the coppice origin plots