Investigation on the beech and oak spatial structure in a mixed forest (Case study: Gorazbon district, Kheirud forest)

For achieving appropriate knowledge on biodiversity with a minimum cost and time to obtain a sustainable forest management, some applicable indices are needed. This study was attempted to describe some spatial structure indices as well as to quantify beech and oak spatial structures in Gorazbon district of Kheirud forest. The indices of uniform angle (UAI), mingling (DM_i), DBH dominance (TD_i) and DBH differentiation (T_ij) were applied to investigate of positioning, mixture and DBH status of neighborhood trees. For this aim, a total of 2149 beech structural groups and 357 oak structural groups were analyzed using Crancod (Ver.1.3) software. The average values of UAI, DM_i, TD_i and T_ij were calculated 0.58, 0.27, 0.53 and 0.45 for beech and 0.57, 0.74, 0.56 and 0.37 for oak respectively. The DM_i clearly showed the difference between beech and oak, whereas the values of UAI, TD_i and T_ij were approximately the same for the studied species. The values of absolute discrepancy algorithm, which employed to quantify difference between beech and oak spatial structures, were 8.8%, 59.3%, 6.2% and 19.2% for UAI, DM_i, TD_i and T_ij respectively. Because of the ability of these indices to precisely demonstrate the differentiation of stands in succession stages and their applicability for comparing the studied stand with others, they can be considered as useful tools for sustainable management.