Intra-specific competition of Persian Oak (Quercus brantii Var. persica) and its relationship with physiographic factors and fine root biomass (Case study: Ghalegol, Lorestan)

The purpose of the study was to investigate the effects of some physiographic factors on competition index (CI) and fine root biomass (FRB) in coppice Persian oak trees (Quercus brantii Var. Persica), and also to determine the correlation between these factors and some characteristics of oak trees in forest of Ghalegol-Lorestan. Randomized blocks sampling method was used to determine the target trees in the site by circular sample plots (n=40). In addition to measuring the DBH of trees and their distance from neighbor trees for determining CI, fine root sampling was done at depth of 0-30 cm and at distance 1m, also in north and south sides of the target trees. The independent t-test showed that the aspect had a significant effect on CI, so that it was more in north-facing than the southern directions (p<0.001). Analysis of variance indicated that slope and altitude influenced the CI of oak trees and also the highest CI was observed at altitude of 2000-1900 m a.s.l (p<0.05). There was a significant correlation between CI and crown diameter of trees (p<0.01). The Pearson correlation revealed that there was no significant correlation between FRB and CI among trees (p>0.05). The independent t-test showed that aspect had a significant effect on FRB (p<0.001). Analysis of variance indicated that slope had no effect on FRB (p<0.05), but elevation showed a significant difference in this regard (p<0.01). Considering the effect of topographic factors on the CI and FRB of Persian oak trees, it can be stated that in silvicultural operations, more attention should be paid to the topography of site and the trees characteristics.