高寒草甸土壤物理特性和微生物数量对模拟践踏的响应

为探明高寒草甸土壤对家畜践踏的响应机制，于甘肃天祝进行了牦牛和藏羊的模拟践踏试验，研究了不同强度模拟践踏对土壤物理特性及微生物数量的影响。结果表明，0～10 cm土层的土壤紧实度和容重，随着践踏强度的增加均呈递增趋势；而呼吸速率和饱和导水率呈递减趋势。0～10 cm土层的3大微生物数量随践踏强度的增大而减小。同一践踏强度下，牦牛践踏后0~10 cm土层的土壤紧实度和容重均大于藏羊践踏处理；而饱和导水率、呼吸速率和微生物数量均小于藏羊践踏处理。综合分析认为，家畜的践踏强度越大，土壤的压实效应越显著；一个生长季的模拟践踏主要影响0～10 cm土层土壤的物理性质；且牦牛对土壤的压实效应和对微生物分布的抑制作用均大于藏羊。

Response of Soil Physical Properties and Microbial Quantities to Simulated Trampling on Alpine Meadow

In order to investigate the response mechanism of alpine meadow soil to livestock trampling,the simulated trampling experiment of yak and Tibetan sheep was carried out in Tianzhu.The effects of different simulated trampling density on soil physical property and microbial biomass were studied.The results showed that the soil compaction and bulk density at the 0～ 10 cm depth increased with the increase of trampling intensity;however,the respiration rate and saturated hydraulic conductivity decreased.Meanwhile,the three types of microorganism reduced with the increase of trampling intensity.At the same trampling intensity,the soil compaction and bulk densityof 0～10 cm soil depth under yak trampling were higher than under Tibetan sheep trampling,while the saturated hydraulic conductivity,respiration rate and microbial biomass under yak trampling treatment were lower than Tibetan sheep trampling treatment.The comprehensive analysis showed that the compaction effect on soil was more significant with the increase of livestock trampling intensity.Simulated trampling of one growing season primarily affected the physical properties at the soil depth of 0 to 10 cm;and the compaction effect on soil and inhibitory effect on microorganism distribution of yak were higher than Tibetan sheep.