Spatial patterns and intra-specific competition of Chestnut-leaved oak (Quercus castaneifolia C. A. Mey.) using O- ring statistic (Case study: Neka Forest, Iran)

The spatial patterns of trees in different stages of their life provide important information related to forest regeneration and succession processes. Since competition affects forest structure, understanding competition is important when forest management aims to imitate the dynamics of natural ecosystems. For this purpose, an unmanaged control forest was selected with 26 hectares area. All Chestnut-leaved oak (Quercus castaneifolia) trees with a diameter at breast height (DBH) greater than 7.5 cm were measured, and their Cartesian coordinates were recorded. Based on their DBH, the measured trees were then divided into four classes of small timber, medium timber, large timber and extra-large timber. The univariate and bivariate O- ring statistic were used to investigate the spatial patterns and to examine the intra-specific competition, respectively. Results showed cluster spatial pattern in short distances due to heavy seed and high regeneration frequency, which was later changed to random distribution as distance increased. Moreover, interactions between diameter size classes showed that oak trees with different sizes had different positive (attraction) and negative (repulsion) interactions which occurred at different scales based on the size of trees, influenced by light-demanding, limited seed dispersal and intra-specific competition of oak trees. Since the Chestnut-leaved oak trees showed random distribution, the silvicultural interventions should thus be based on individuals and random single selection to create random spatial patterns in the stand.