عنوان مقاله [English]
Background and objectives: Analysis of spatial pattern and association of inter-tree species in the developmental stages in natural stands is a prominent prerequisite for simulating, founding and extending forest ecosystems. This study aimed to obtain appropriate information for extending sustainable development and simulation, and performing close-natural silviculture in a non-protective site using this technique for endemic species including Caspian poplar and Ironwood trees in Nour Forest Park forest.
Materials and methods: In the studied site, the developmental stages consisting of initial, optimal and decay stages were determined in each area of one hectare using the specified indices, and coordinates of target species were taken by GPS and trigonometric relationships. To map spatial patterns of each tree species and competition model for inter-tree species, univariate and bivariate function of K-Ripley were used in the study. As such, Monte Carlo simulation was used to test the null hypothesis of a random distribution and interaction relationships. The associations were classified into repulsion, independent and attraction relationships in this technique.
Results: The findings of univariate function showed that Caspian polar trees were clustered in the distances of 9- 14 m, > 7 m and 8- 35 m in the initial, optimal and decay stages, respectively, and this species, however, was randomly distributed in other distances. The results for Ironwood trees showed random pattern in the initial stage, cluster pattern in distance of 20- 39 m and 6- 32 min the optimal and decay stages respectively, and either random or clustered patterns in the other distances. There were no regular patterns for these species in the different stages. Furthermore, the results of bivariate function indicated that there were attraction relationships between Caspian poplar and Ironwood trees in the majority of distances in developmental stages though there were also independent associations in some distances within the different developmental stages.
Conclusion: According to the findings, the specified spatial patterns of each tree species would be affected by natural events. َAlso, The results showed that there was no regular relationship for each studied tree species in the studied forest. The finding showed that there were independent and attraction relationships between two studied species in some distances in the developmental stages. However, there was no repulsion association between Caspian poplar and Ironwood trees in the forest. since there were found no inter-species repulsion relationships, high density of Ironwood trees could be in association with density of Caspian poplar trees in the studied forest.