Resistance of tree species to snow damage in Nav Asalem forests, Guilan province

Management of mountainous forests implies detailed information on the extent and intensity of snow damages. Furthermore, such information is required for improved conservation of natural stands. In this study, snow damages on six dominant tree species including Beech (Fagus orientalis Lipsky), Hornbeam (Carpinus betulus L.), Velvet Maple (Acer velutinum Boiss.), Cappadocian Maple (Acer cappadocicum Gled.), Caucasian Alder (Alnus subcordata C. A. Mey) and Chestnut-leaved Oak (Quercus castaneifolia C. A. Mey.) were investigated across a portion of the Nav forest in the east of Guilan province. Circular 0.1-ha plots were systematically sampled in a grid with 100m sampling distance. Four types of tree damage were detected including crown damage (8.6%), stem breakage (5.5%), uprooting (3.2%) and bending (1.4%). The six studied tree species have different resistance to snow damage. The highest rates of uprooting and stem breakages were observed in Alder trees. The Oak trees were mostly influenced by crown damages. Furthermore, the Beech trees showed the lowest rate of crown damage and stem breakage. Based on the results, the tree species of Alder, Oak and Cappadocian Maple were categorized as being more vulnerable to snow risk, whereas Beech, Hornbeam and Velvet Maple proved to be less vulnerable. In addition, the slenderness coefficients were calculated for bended trees (76.7), stem broken trees (64.5), uprooted trees (64.0), crown damaged trees (60.1) and intact trees (50.2). This study also showed that trees of higher slenderness coefficient are more vulnerable to the snow risk.