Structural Diversity within Mature Forests in Northern Iran: A Case Study from a Relic Population of Persian Ironwood ( Parrotia persica C.A. Meyer)

Persian ironwood (Parrotia persica C.A. Meyer) is a deciduous tree that is endemic to the Caspian forests of northern Iran. The restricted geographic range of Persian ironwood makes human disturbance the highest threat to the persistence of this species. The objectives of this study were to contrast the structural diversity of three native stands of Persian ironwood using common structural indices and measure the range of intraspecies and interspecies competition. Our results showed that Persian ironwood tends to be fairly pure in species composition and have slightly heterogeneous diameter distributions and uniform tree height, and the stems have an average distance between trees of 6.0 m. Persian ironwood appears to be a successful competitor for space and light compared with other tree species; however, we found relatively little evidence of interspecies competition. Based on the results of this study, if efforts to restore this endemic species involve artificial regeneration, plans should include mimicking the relative purity of the stands because changes in the structure and composition of Persian ironwood stands may alter competition and affect seedling survival and the overall success of conservation efforts.