مجله جنگل ایران (Dec 2015)
Snow damages on trees in natural and managed stands of the Caspian forests, North of Iran
Abstract
Forest management has a decisive role in decreasing or increasing snow damages on trees due to effects on stands structure. In this research snow damages on trees were investigated and compared in managed and natural stands with selection silvicultural system in Nav-Asalem Forests, Guilan province. Circular 0.1 ha sample plots were established using random-systematic method for studying the effects of snow on different species with various ages. The distance between sample plots were set to 100 m. The results showed that the frequency of snow-damaged trees in managed stand (10.2%) was significantly higher (P < 0.01) than natural stand (7.2%). The occurred changes in the age structure and tree species composition in the managed stand during selection cuts was the main cause of most snow damage in this stand compared to natural stand. The most frequency of damages was observed on young trees with high slenderness coefficient. For fortifying the studied forests against risk of snow damage the following recommendations can be mentioned: increasing the selection cutting period from 10 to 20 years, reducing the removed volume in each logging period, reducing the areas of regeneration gaps, increasing the number of large trees, avoiding the cutting trees in forest edges, implementing the thinning operation in the stands in which previous cuttings caused homogenous, even aged, young stands with high slenderness coefficient, and avoiding tree cutting in the areas that are sensitive to snow damage such as ridges, steep slopes with low depth of soil.
