Analyzing the effect of clustered spatial distribution of mount Atlas mastic (Pistacia atlantica Desf.) trees on their biometric characteristics using mark-correlation function in Baneh Research Forest, Fars province

Abstract

The spatial distribution analysis of trees in arid and semi-arid regions presents valuable information about their interactions and impacts on one another. This study was aimed to investigate how biometric characteristics of mount Atlas mastic (Pistacia atlantica Desf.) are influenced by their clustered spatial distribution in Zagros vegetation zone. For this purpose, a part of Wild Pistachio Research Site, Fars province, was selected and in addition to registering the position of all trees with > 2.5 cm diameter at breast height (DBH), DBH, height, and crown area of each tree were measured. Wild pistachio trees with DBH > 10 cm and < 10 cm were classified as adult and sapling, respectively. To achieve the aims of study, univariate and bivariate forms of mark variogram and mark-correlation function (γ(r), kmm(r), γm1m2(r) and km1m2(r), respectively) were applied. The observed pattern of wild pistachio trees showed significant spatial heterogeneity as compared to homogeneous Poisson process (α=0.05). This heterogeneity was caused by unfavorable environmental conditions of study area. The results of univariate and bivariate γ(r) and kmm(r) showed that DBH, height, and crown area of wild pistachio trees located at three meter distance from each other were less than overall average. Moreover, the results showed that investigated biometric characteristics of wild pistachio saplings that wild pistachio adults were located up to three meter distance from them were less than overall average. In general, it was concluded that aggregation of wild pistachio trees because of environmental heterogeneity negatively influenced their biometric characteristics and prevented their increase.

Keywords

• Mark-correlation function
• spatial distribution
• variogram
• Zagros