呼伦贝尔草原风蚀坑土壤水分异质效应研究

Heterogeneity of soil moisture of blowouts in HulunBuir grassland

风蚀坑是沙质草原常见的一种风蚀地貌,是草地沙化的一种重要表现形式,其对草原植被破坏性强。本文选择呼伦贝尔草原处于活跃发展阶段的风蚀坑为研究对象,并以周边草地为对照,对风蚀坑内外不同位置、不同深度的土壤含水量进行研究。结果表明:(1)风蚀坑造成草原土壤水分的“破口”效应,导致其周边近20 m范围草地土壤含水量显著降低,且在沙坑边缘0~3 m范围内形成了一条“干燥带”,其土壤含水量比对照低45.15%;(2)沙坑内土壤含水量较对照降低44.44%,但沙坑下风向积沙区土壤含水量与对照无显著差异;(3)风蚀坑的沙坑及积沙区不同深度的土壤含水量异质性较大,变异系数C_(V)可达到50%以上,且随着土层深度的增加,土壤含水量呈现先增大后减小的趋势;(4)经过雨季,风蚀坑的积沙区有一定的“储水”作用,而沙坑及边缘区却呈现出严重的“失水”效应,土壤处于极度干燥状态,为沙坑的风蚀扩张提供了条件。

Blowout is an important manifestation of grassland desertification that is a common for a wind erosion landform in sandy grassland and is highly destructive to grassland vegetation.The blowouts that were in the active development stage of HulunBuir grassland were the object of this research,and the surrounding grassland was the control in which the soil moisture was measured in different locations and different depth.The results show the following:(1)Blowouts caused the“crevasse”effect of soil moisture in grassland that lead to a significant decrease in the soil of the surrounding grassland in a range of nearly 20 m.A close proximity to the pit results in lower soil moisture,A“dry zone”was formed in the range of 0-3 m at the edge of the pit,and the soil moisture was reduced by 45.15%compared with the control.(2)Soil moisture of the pit decreased by 44.44%,and no significant difference was observed in the soil moisture between the surrounding sand accumulation area and the lightly overlying sand area compared to the control.(3)There was a great difference in soil moisture of the pit in the soil layers and sand accumulation area.Cvcould reach more than 50%.As soil depth increased,the soil moisture increased first and then decreased.(4)The sand accumulation area of blowouts could realize a certain“water storage”effect after the rainy season,the pit and edge zone had a serious“water loss”effect.The soil was extremely dry soil provided conditions for the expansion and morphological development of blowouts.