三江源区草地退化与人工恢复对土壤理化性状的影响

以三江源区不同退化程度的天然草地及不同恢复年限的人工草地为研究对象,系统分析土壤理化性质随取样深度的动态变化。结果表明:(1)人工草地土壤含水量及全氮、全钾、全磷、速效钾、速效磷的含量随恢复年限均表现出先减小后增大的"V"形变化趋势;(2)随着退化程度增加,退化草地土壤中含水量逐渐降低,全氮、全钾、有机质、速效钾含量未表现出逐渐降低趋势,而草地的裸斑面积、土壤及养分的流失量逐渐增加;(3)人工草地及退化草地土壤中全氮、速效钾、有机质含量均随着取样深度增加而逐渐降低,草地恢复年限和退化程度基本不影响养分在土壤中的空间分布;(4)人工草地建设使退化草地有机质、全氮、全钾的含量增加,尤其有利于0-4cm的土壤养分增加。因而,人工草地建设可以作为三江源区退化草地土壤恢复的措施之一。

Effects of Grassland Degradation and Artificial Restoration on Soil Physicochemical Properties in Three-river Headwater

The depth variations of soil physicochemical properties in the degraded native grasslands and the artificially restored grasslands were studied in Three-river headwater areas of Qinghai-Tibetan plateau,China.The results showed:(1)With the increase of the gradient of restoration years,soil water content,total nitrogen,total potassium,phosphorus,available phosphorus and potassium were decreased firstly and increased thereafter,had a "V" type change in the artificial grasslands.(2) With the increase of grassland degradation gradient,soil water content was gradually reduced,but the total N,K,the organic matter didn’t gradually reduced.The bare land area,soil erosion and the loss of the soil nutrient increased significantly with the increased degradation grades.(3)The total N,K,the organic matter were declined gradually with the increase of soil depth,so both restoration years and degradation degree didn’t influence the nutrient distribution in soil.(4)The organic matter,total N and K of degraded grassland were increased by artificial grassland construction,especially soil nutrients of 0-4 cm.Therefore,artificial grassland construction can be used as a measure of soil restoration of degraded grassland in the Three-river headwater area.