The Influence of Geomorphological Characteristics of Forest Sites on the Decay Dynamics of Dead Trees in Asalem Forests, Western Hyrcanian Region

Knowledge of the decay trend of dead trees and site factors affecting their functions, plays an important role in the development of conservation management plans in forestry projects. This research was conducted in Asalem beech forests in northern Iran to assess the impact of physiographic features of the site on the process of dead trees decay. A total of 90 sample cuts of dead beech stumps were randomly selected and studied. For each sample, species, diameter and decay classes were recorded. The effect of aspect Slope Index (ASI), Terrain Shape Index (TSI) and Landform Index (LI) on the physical properties of dead wood (density, weight, moisture content) and biochemical components of wood (lignin, cellulose and hemicellulose) on the process of decay were investigated. The mean decay rate of dead beech stumps calculated 0.061 and the mean of beech was 0.32 that varied between 0.05 and 0.62 grams per cubic meters. The results revealed decay process requires about 46 years and the four classes decay showed significant difference in terms of wood density, lignin and cellulose. Meanwhile, the LI was the most important physiographic factors influencing the decay rate of dead trees. The lignin content of the deadwoods was significantly influenced by the form of land. Accordingly, it can be concluded that maintenance certain volume of dead tree in the forest stand structure need to taking account into the dynamics of dead trees, as well as the effects of geomorphological characteristics of site, especially land form conditions