Intraspecific interaction comparison in Populus euphratica stands using Mark correlation function in Behbahan Chaharasyab area

Abstract

Background and objectives: Intraspecific interaction is important because it occurs between the same species individuals that have similar ecological nests. The objective of this study was to evaluate intera-specific interaction of poplar trees (Populus euhratira Olivier.) using mark correlation functions. Materials and methods: The position of all trees with DBH>2.5 cm were recorded in two pure and mixed stands in Behbahan Chaharasyab area with area of 4.5 and 9.1 ha, respectively. Tree height (H), diameter at breast height (DBH), crown diameter (CD) and light crown length (LCL) were measured as mark variables. Point spatial pattern analysis was used to study the spatial pattern and intraspecific interaction. Marked correlation (MCF) function was used to reveal the spatial relationships between the poplar individuals trees in terms of various characteristics such as total tree height, diameter at breast height, crown diameter and light crown length. Results: The results showed that in pure stand, a significant negative correlation was observed between the DBH of trees at a distance of less than 5 and more than 20 m. Between distances of 5 to 20 m, an independent state was observed between the individuals. There was a positive and negative correlation between the crown diameter of poplar trees from a distance of 5 to 40 m and more than 45 m, respectively. There was a significant positive correlation between the total height and the light crown length of the trees from a distance of 5 to 30 m. At a distance of more than 30 m, the independence was seen between the individuals. In mixed stand, the independence status was observed between DBH of trees up to a distance of 40 meters. A positive correlation was observed at distances greater than 40 m. There was a negative correlation between trees CD at all distances. The independence was seen between H and LCL of trees at most distances. Conclusion: In pure stand, depending on different distances and marks, various states of interaction including negative, positive and independence were seen between the tree individuals. While in mixed stand, except for the state of negative interaction that was seen in relation to the crown diameter, in other cases, the condition of independence between different individuals was observed in terms of the studied marks. DBH showed similar conditions in both pure and mixed stands. CD showed positive and negative correlations between individuals in pure and mixed stands, respectively. There was a positive correlation between H and LCL of individuals in pure stand while independence was observed in mixed stand. Overall, it is useful to study the interaction between poplar trees to understand the dynamics, growth process and mechanisms that endanger this valuable species.