不同土地利用方式下土壤风蚀主要影响因子研究——以内蒙古武川县为例

Main affecting factors of soil wind erosion under different land use patterns—A case study in Wuchuan County,Inner Mongolia

以内蒙古武川县为例,选取天然草场、旱作农田(马铃薯)和退耕人工灌木林3类农用地为研究对象,对影响土壤风蚀的气候、植被覆盖度、土壤特性等若干因子进行了野外实测、室内分析及风洞模拟试验.结果表明,降雨少、风大、风多、土壤质地粗糙以及冬春冻融交替作用造成土壤表层疏松干燥等原因,决定了春季是该地区土壤风蚀的易发期.植被覆盖度是影响土壤风蚀的重要因子.在冬春风蚀季节覆盖度高低依次为灌木地>天然草地>旱作农田,此时缺少地表覆盖物保护的旱作农田最易受到风蚀危害.土壤含水量是影响风蚀的另一个重要因子.通过风洞试验对土壤风蚀率与含水量的定量关系研究表明,土壤含水量越高,土壤启动风速越大,风蚀率越小.6%土壤含水量是旱作农田风蚀强度由强变弱的一个转折点.田间试验结果表明,不同土地利用方式下表层土壤含水量总体上表现为天然草地>旱作农田>灌木林.通过风洞试验对土壤水分和风速的定量化研究表明,土壤风蚀速率随风速的增大而增大,二者呈幂函数关系.在净风吹蚀的条件下,18 m.s-1风速是风蚀强度急剧增加的一个转折点.

Field investigation, laboratory analysis and wind tunnel simulation showed that in Wuchuan County of Inner Mongolia, low precipitation, frequent and high wind velocity, coarse soil texture, and thawing and freezing were the main causes of soil wind erosion happened very easily in spring. In late winter and early spring, the vegetation coverage was in order of shrub-land 〉 natural grassland〉 rainfed farmland, and thus, increasing the surface cover of rainfed farmland should be an urgent need to control the wind erosion in Wuchuan County. The soil wind erosion rate decreased exponentially with increasing soil moisture content, and 6 % soil moisture content was a turning point from severe to light. The topsoil moisture content under different land use patterns was in order of natural grassland〉 rainfed farmland 〉shrub-land. With increasing wind velocity, soil wind erosion rate increased by power function, and 18 m·s^-1 wind velocity was a switching point to aggravate the wind erosion.