Anthropogenic disturbance impacts on spatial pattern of Caucasian oak (Quercus macranthera) stands in the Hatam Mashe Si forests, Arasbaran

Knowing the effects of anthropogenic disturbances on the natural spatial pattern of trees can provide good information about the response of nature to human intervention. This study aimed to reveal the effects of human interventions on the spatial pattern of Caucasian oak stands in the Arasbaran region, located on Hatam Mashe Si, Meshgin-Shahr. For better distribution of study locations, three areas with different disturbance intensities were selected and the nearest tree to the transect as a reference tree with the four nearest neighbors was measured. To analyze the spatial pattern of trees, two groups of indicators based on the nearest neighbor’s distance index were used, including distance-dependent indices (distance from the nearest neighbor, Clark-Evans, and Pielou), and angle-dependent indices (mean directional, mean of angles, and uniform angle). The results showed that the average distance to the neighborhood in areas with high intensity of disturbance is significantly more than the other two areas. As the disturbance index increases, the distance between the trees and the numerical value of the Clark-Evans and Pielou indexes increases. The mean angle index showed a moderate and positive relationship and the uniform angle index showed a negative relationship with the anthropogenic disturbance index, and the mean directional index did not show a relationship with the anthropogenic disturbance index. Anthropogenic disturbances (such as cutting trees, livestock grazing, and fires) in the long term have led to changes in the spatial pattern of trees, as a result, their distribution is relatively regular. In conclusion, it can be concluded that minimizing the effects of anthropogenic disturbances in forests can partially maintain the heterogeneity of the forest structure.