Diversity of tree and shrub species in relation to topographic factors and stand characteristics in oak forests of Ilam province. (Case study; Miantang forests in shirvan -chardavol)

To study of diversity of tree and shrub species in relation to topographic factors (elevation، slope، aspect) and some of stand characteristics (canopy density، basal area، diameter، number of dbh classes، number of tree and shrubs)، area about 460 ha of Miantang forests located in north of Ilam province was selected. Then 46 plots 2000m2 were established in accordance to Minimal area method. Variables in each plot were included tree diameter (DBH)، crown maximum and minimum diameter for all trees، number of tree and shrub species، elevation، slope and aspect. Values of diversity indices were computed by PAST software and analyzed with variance analyze، Duncan test and correlation. Totally 11 tree and shrub species were presented in the plots which the most presentation was belong to the Quercus persica. Results showed that elevation، slope and aspect have significantly affected on diversity، richness and evenness of tree and shrub species. The midle elevation classes had the most species richness and diversity. The south aspect had the most richness، diversity and evenness. Also the amount of diversity indices increased with the ascending of the slope، but in over of 60% was decreased. Canopy density and number of tree and shrubs (n/ha) had positive correlation with richness but negative correlation with diversity and evenness.