Wind-Thrown Trees Characteristics and Effects of Topographic and Soil Factors on Wind Throw in Chamestan Forest- Mazandaran

Windthrow of trees is a common ecological phenomenon in the forests of Hyrcanian region. The forest stands of 22 in series of 12 of Haraz Forest plan is one of the stands with high percent of wind-thrown trees. The purpose of this study is to investigate the role of physico-chemical properties of soil, topographic factors, characteristics (slope and direction) of Parcel 22 and compare it with adjacent areas in order to find environmental variables effective in increasing Windthrow rate.

In the study area, completely randomly, 15 sample plots (10 Are) were measured in the center of the Windthrow trees. For the investigation of this problem, in an area of 88 hectares, about 400 wind-thrown trees were 100% surveyed and their quantitative and qualitative characteristics were recorded. Furthermore, the characteristics of windthrown trees in different physiographic conditions (i.e., different slopes and aspects) and soil characteristics (i.e., bulk density, texture, EC, carbon: nitrogen ratio and soil total nitrogen) of this stand and near stand (without wind-throw) were investigated.

According to results, most of the damage belong to trees that was uprooted trees and wind throw trees in flat lands were more than steep lands. Most precent of wind throw trees were in slope 0 and 5 % and 67% uprooted trees were in this section. The most uprooted trees were belonging to Parrotia persica (44%) while, the lowest uprooted trees were recorded for Acer velutinum and Alnus saubcordata species (<5%). The results of independent t-test showed that soil moisture content in the soil of windthrow trees was significantly (95 %) higher than the control area. Also, Carex acutiformi species includes 4.47% of herbaceous species in the wind throw area, while it was not seen in the control area.

Finally, the results of this study showed that the construction of dams upstream has changed the soil moisture content and increased the sensitivity of species such as Parrotia persica to wind. Meanwhile, the resistance of forest species in the face of stable soil moisture changes and the occurrence of strong winds has been different, so that moisture-loving species such as Acer velutinum and Alnus saubcordata (due to moisture-friendly and insensitive to increase soil moisture) with lower rainfall intensity Showed.