Spatial patterns, competition and spatial association of trees from different development stages in mixed beech (Fagus orientalis Lipsky) stands

This research was conducted to study the spatial patterns, inter and intra-specific associations of tree species that may provide valuable insights into processes and mechanisms that maintain species coexistence. Data collection was done using three one-hectare (100 m × 100 m) plots from three development stages (initial, optimal and decay) in an intact mixed beech forest. The positions of all trees with diameter at breast height (DBH) larger than 7.5 cm were recorded using azimuth-distance method. The measured trees were then divided into four diameter size classes. Spatial patterns and spatial associations among tree size classes (intra-specific) and among species (interspecific) were analyzed using univariate and bivariate Ripley’s K-function. Results indicated that spatial patterns of trees are aggregated, slightly aggregated and random for initial, optimal and decay stages, respectively. Over time, shade-tolerant nature and intra-specific competition of beech trees from different size classes as well as inter-specific competition between beech- hornbeam and among beech- other species across different development stages indicated the different situations. Structural differences, various ecological nature, various reaction of different species to environmental variables at different life stages, difference in growth and physiological mortality due to mixed studied stands can be considered as effective factors in these difference. Knowledge about spatial pattern and natural events are the prerequisite for the implementation of targeted silvicultural interventions and commensurate with the potential and development stages of forest stands.