退化草地恢复生态对土壤物理性状的影响——以藏北公路沿线车辆碾压干扰矮嵩草草甸为例

Effects of Ecological Restoration of Degraded Grassland on Soil Physical Characteristics——As an Example of Trampling Disturbance on Kobresia Humilis Grassland Alone Qingzang Road in North Tibet

通过对西藏那曲地区碾压干扰矮嵩草草甸群落不同恢复演替阶段土壤物理性状调查,分析不同演替阶段土壤颗粒组成、土壤容重和孔隙度,对其物理特性进行研究。结果表明:植被恢复有效改善了土壤的物理性质,提高了土壤对侵蚀动力的抵抗能力;退化草地恢复演替阶段与土壤物理性状变化具有明显的相关性联系,植被恢复与演替有效改善了土壤的物理性质,提高了土壤对侵蚀动力的抵抗能力。(1)碾压使土壤暴露,致使侵蚀作用加剧,松散、不黏结的砂粒和粉粒流失量较大,而粒径小于0.02 mm和黏结性较强的粘粒流失量相对较少而表现出百分比相对增加;碾压改变原有土壤的正常质地层次构造,对公路沿线的土壤物理性质产生不良影响,促使土地进一步退化。(2)随着恢复进程,表层土壤总孔隙度增大,土壤容重减小,与演替阶段均极显著相关;随着土壤的通气性和渗透、排水率的改善,土壤有效水分增加。

The process of vegetation restoration and succession had improved soil obviously in degenerated ecological system especially soil physical characteristics in series of succession stage in naqu county North Tibet are investigated here; and ratio on soil grain composition in series succession stage are analyzed; meanwhile, soil bulk density and porosity are measured . The correlation analysis between soil physical characteristics such as soil grain composition, soil bulk density and porosity and soil succession stage are made in this paper, and then a inherent concern between succession stage of degraded grassland and the change of soil physical characteristics in this region are probed. （1）Trample makes the soil expose, that cause the function of corroding to aggravate;loose sand grain and slit that does not cohere had lost heavily, but the lost of grain which smaller than 0. 02 mm and cohesive soil was relatively less, so that it was demonstrated percentage to be relative to increase strong directly; As a result, trample had changed the normal structure of the original soil, and influenced on the soil physical properties badly along the line of the highway, and impel the land to be further degradative. （2）With the process of restoration, the top layer soil total porosity increases, and bulk density is reduced, above all relevant with the series succession stage prominently; With improvement of aeration, infiltration and drainage percent, the availability of moisture soil increases corresponsively.