Quantifying the Spatial Structure in Hyrcanian Submountain Forest (Case Study: Gorazbon District of Kheirud Forest-Noushahr-Iran)

Quantifying spatial structure is one of the most important components, describing natural ecosystems and their biodiversity. In this study, a set of indices and functions related to spatial structure using 102 established plots with an area of 1000 m2 were presented. To achieve spatial structure of Carpinus-Fagus type, a set of indices (Clark & Evans, uniform angle, Shannon-Wiener, mingling and DBH/Height dimension) and functions (pair correlation and mark correlation) were applied. The indices and functions demonstrated the diversity of tree positioning, species, and tree dimension. The mean values of Clark & Evans and uniform angle indices were 0.86 and 0.53, respectively, indicating a distribution between random and cluster patterns. Also, pair correlation function indicated trees with inter-tree distance smaller than 5.5 m were more than the same forest with a random distribution. The mean values of Shannon-Wiener and mingling indices were computed 1.17 and 0.36, respectively. Mingling index properly showed a low mixture of beech and hornbeam and a high mixture of other species. Furthermore, the mean values of both DBH/Height dominance indices were 0.51, which indicated that some species such as linden and alder were dominance and species including elm and persimmon were conquered. Mark correlation function showed that trees with inter-tree distance less than 7.5 m had a smaller DBH rather than the average of forest. The utilized indices and functions in this study had a high ability in describing of available species structure in Carpinus-Fagus forest type, so the result could be applied in sustainable forest management.