Application of gap models in projection of basal area increment of commercial trees in the ‎Hyrcanian region based on climate change effects (Case study: Gorazbon district, Kheyrud forest ‎research station)‎

Climate change studies and simulations conducted by GCM models show that patterns of temperature and rainfall will change over the next 50 to 100 years can affect patterns of forest stands increment. Growth and yield models do not have the ability to simulation forest stands under the effect of climate change. Due to lack of efficient models, JABOWA-4 as a hybrid model that can evaluate the population dynamic under climate change scenarios, and can explore the long-term aspects of forest composition, was applied in this study. In order to uncertainty of climate change trend in future, three greenhouse emission scenarios were formulated to explore future global developments with special emphasis on greenhouse gases. After comparison of modeled and real values of diameter growth, R2 and RMSE were calculated to be 0.98 and 1.734 (cm2), respectively, indicating a good correlation between two mentioned values. The response of species to climate change were assessed separately for Beech and Maple with 31 and 25 percent reduction in DBH increment, respectively, wich showed a negative response to climate change. Oak projected to increase slightly and after that decreased by17 percent under climate change and Hornbeam showed positive response to climate change but less than real values. The results of this study indicated that gap models are good at providing forest yield prediction affected by climate change.