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一、林区发生倒木的原因新疆山区天然林中出现倒木的原因总体来说都是由于自然灾害性天气造成的,大风造成倒木的比重最大,其次为洪水和大雪。新疆山区的天然林主要为天山云杉,云杉属于浅根性树种,通常根系分布于40～60厘米左右厚的土层内。幼树主侧根系比较明显,10～15年后主侧根难以分辨。天山云杉寿命能够达到400年以上,树高达70米。林区冷暖空气交替明显,容易引起大风,加上林区高低起伏地势变化非常大,风向千变万化,高大的树木、浅薄的根系加上林区潮湿的土壤,树木极易被大风刮倒。森林中的树木之间原本相对稳定的平
I. Causes of fallen woods in forest areas The reasons for fallen wood in natural forests in mountainous areas of Xinjiang are generally due to natural disastrous weather. The proportion of fallen wood caused by strong winds is the largest, followed by floods and heavy snowfall. The natural forest in the mountainous area in Xinjiang is mainly the Tianshan spruce. The spruce belongs to the shallow-rooted tree species. The root system usually distributes in thick soil layers of 40-60 centimeters. The main lateral root system of saplings is obvious, after 10 to 15 years, the main lateral root is difficult to distinguish. Tianshan spruce life can reach more than 400 years, the tree up to 70 meters. Alternating cold and warm air in the forest area is obvious and easy to cause strong winds. In addition, the ups and downs in the forest area vary greatly and the wind direction is ever-changing. Tall trees and shallow root systems add to the moist soil in the forest area and the trees can easily be overwhelmed by the strong winds. The original relatively stable between the trees in the forest