不同强度放牧后自然恢复的沙质草地土壤性状特征

Characteristics of Sandy Grassland Soils under Post-grazing Natural Restoration in Horqin Sandy Land

通过对科尔沁沙质草地不同强度放牧后自然恢复过程中土壤的物理、化学和生物学性状特征的研究 ,结果表明 ,土壤有机碳、全氮、全磷、有效氮和速效磷含量以及基础土壤呼吸活性在各处理表层土壤的特征为 :中牧后恢复草地 >轻牧后恢复草地 >无牧恢复草地 >重牧后恢复草地 ;重牧后的恢复草地表层土壤较其它处理有较高的土壤容重和pH值以及较低的过氧化氢酶、脲酶和碱性磷酸酶活性 ;沙质草地的土壤养分和生物学活性在剖面中的分布为上高下低 ,主要富集于 0～ 2 5cm表层 ,放牧对土壤系统的影响主要表现在 0～ 7 5cm土层。重度放牧使沙质草地超出了其承载能力和承受干扰的阈限 ,土壤性状恶化 ,恢复力降低 ;

The characteristics of soil physical, chemical and biological properties of sandy grassland in natural restoring processes after different grazing intensity disturbance were studied. Contents of organic carbon, total nitrogen and phosphorus, available nitrogen and phosphorus, and basal soil respiration in topsoil among different treatments have significant differences: post-moderate-grazing restoration plot>post-light-grazing restoration plot>non-restoration plot>post-heavy-grazing restoration plot. Soils in post-heavy-grazing restoration plot exhibit higher bulk density and pH values, and lower Catalase, Urease, and alkaline Phosphatase activities compared to other plots. Soil nutrients and enzymes in sandy grassland concentrate in the upper layer of the profile and decrease with depth. The effects of grazing livestock on soil properties occurred in the 0～7.5 cm soil layer. Heavy grazing has overtaken the threshold of sandy grasslands carry capacity and the threshold of resistance to disturbance, which worsens soil properties and weakens resilience. However, moderate grazing enhances the cycling of soil nutrient materials and favors the maintenance and improvement of soil fertility and soil resilience.