Inter-specific competition of juniper trees in Kandiragh forest reserve using O-ring statistic and mark correlation function

Forest reserves are a shrinking pattern of biosphere reserves in which unique and rare or endangered species grow naturally. Juniper genus is one of the few indigenous conifers of Iran with habitats in large areas of the country. However, nowadays, despite its importance, there is a declining trend that is particularly critical in areas without control and management. The purpose of the study was to investigate and quantify the inter-specific competition of juniper trees (Juniperus excelsa) with the main associated species, namely pistachio (Pistacia atlantica) and maple (Acer monspessulanum), in Kandirigh forest reserve in Ardabil Province of north-west of Iran. For this purpose, full census inventory was taken in a protected area of 13.2 hectares, and variables of DBH, total height and crown diameter and spatial coordinates of all tree species were recorded. Then, the bivariate O-ring statistic and mark correlation function (MCF) were used to evaluate the competition between the junipers with pistachio and maple. Bivariate O-ring statistic showed that most of the interactions of these three species are independent or, ultimately, at small scales are attractions. Univariate and bivariate mark correlations function also showed that the interested variables of DBH, total height and crown diameter were spatially independent. All of this is due to the lack of significant competition between juniper trees and the associated species in this forest reserve. Thus, pistachio and maple can be introduced as associated species for the reforestation and enrichment of the other juniper habitats with similar conditions.