Comparison of spatial patterns and interspecific association of Gall oak (Quercus infectoria Oliv.) and Lebanon oak (Q. libani Oliv.) in two less degraded and degraded oak stands in northern Zagros (Case study: Khedr Abad, Sardasht)

Spatial pattern and interspecific association between plant species are two important measures for understanding relation between species and their surrounding environment. Regarding the importance of Zagros forests as well as the role of spatial patterns in forest management, this study aimed to investigate spatial patterns of two important species “Quercus infectoria Oliv. and Q. libani Oliv.” in northern Zagros forest. Two forest stands of 5 ha each located in Khedr Abad of West Azerbaijan province were fully calipered. Cartesian coordinates for all trees location were computed and the trees locations were mapped for both stands. Riply’s K function and L(r) and O (r) statistics were used to analyze spatial patterns and interspecific association between plant species. Results showed a clumped pattern for Q. infectoria in less degraded stand using L(r) statistics, while Q. libani tended to random pattern. Using O (r) statistics, the spatial pattern for both species in less degraded stand were clumped that tended to random. However, both species showed a clumped pattern in degraded stand using both statistics. Bivariate statistical analysis showed a positive association between the two species at small scales in less degraded stand, whereas at larger scales the species were independent. Furthermore, the two species were positively correlated at all scales as shown by both statistics. Based on the results, mixed tree plantation is recommended to restore degraded stands via reforestation programs.