Climate and environmental impacts on beech and oak wood production in the Hyrcanian forests

Environmental and climatic conditions influence growth of the trees as well as beech (Fagus orientalis Lipsky), a species which is widely spread in the Hyrcanian forests in  northern region of Iran. However, in the northern border of the forests, Oak (Quercus macranthera) dominates. Despite the variation in the growth and environmental preferences of beech and oak trees, but experiencing similar climatic and   environmental impacts. Therefore, the response of the species could be evaluated simulteneously in various watershed districts. Height and standing volume of Fagus orientalis Lipsky and Quercus castaneifolia as  wood producing criteria in response to changes in precipitation, temperature, evaporation, longitude, latitude, elevation and ratio of forest cover to total watershed areas across Hyrcanian forest from Astara to Golidaghi-Golestan was investigated. Results showed, mean forest cover elevation increase significantly with increase in longitude but decreased as latitude increases. The ratio of forest covers to total watershed district areas decreased with increasing longitude and latitude. K-means Cluster Analysis for all variables has been done in 2, 3, 4, and 5 cluster groups using SPSS statistical software to produce cluster dendrograms. In all cluster groups, forests category groups were; height and volume of beech, height and volume of oak, precipitation, the ratio of forest cover area to total areas of watershed districts and temperature, The outcome of this research showed that, beech and oak wood production and growth are primarily affected by the precipitation, the ratio of forest cover to total watershed areas and the temperature, and in the secondary level by longitude, latitude and evaporation. Pearson Correlation at the significance levels of 0.01 and 0.05 are presented.