高寒草甸表层土壤物理性状对短期放牧的响应

为探讨不同放牧强度对高寒草甸土壤物理性状的影响,设重度放牧(HG)、中度放牧(MG)和轻度放牧(LG)3个放牧强度样地,调查放牧样地表层土壤(0~10cm)的土壤容重、孔隙度、土壤饱和含水量、田间持水量、有效含水量并土壤持水和入渗性能。结果表明,LG和MG的初始含水量、毛管持水量与非毛管持水量均显著高于HG,LG的土壤饱和含水量和田间持水量均显著高于HG,但3个放牧强度间土壤容重、孔隙性状、土壤有效含水量和非毛管持水量均无显著变化;入渗曲线高低为LGMGHG,用模型模拟曲线,拟合精度为Horton模型通用经验模型Philip模型Kastiakov模型;初始入渗率、平均入渗率、稳定入渗率和90min入渗总量均表现为LG显著高于HG;土壤入渗性能均与土壤初始含水量、总孔隙度、非毛孔隙度、通气孔隙度、饱和含水量、田间持水量、有效含水量、非毛管持水量、毛管持水量、最大持水量显著正相关,与土壤容重显著负相关,与毛管孔隙度相关性不显著,但初始入渗率与初始含水量、田间持水量、有效含水量及毛管持水量无显著相关性。回归分析表明,土壤通气孔隙度和有效含水量是影响入渗率的限制因子。短期轻度放牧有利于土壤持水和导水,降低土壤物理结构退化风险;Horton模型适用于该区放牧草地入渗过程的模拟。

Effect of grazing intensity on soil physical properties in an alpine meadow

Effects of grazing intensities (high grazing intensity,medium grazing intensity and light grazing intensity)on soil physical properties (bulk density,porosity,soil water storage capacity,field holding capacity and infiltration)were studied in this paper.The results showed that initial moisture content,capillary moisture capacity and non-capillary porosity water holding capacity for medium grazing intensity (MG)and light grazing intensity (LG)were significantly higher than that for high grazing intensity (HG).Saturated soil moisture and field holding capacity for LG were significantly higher than that for HG.However,the differences of soil bulk density,pore properties,effective water and non-capillary porosity water holding capacity between three grazing intensities were insignificant.The order of infiltration rate was LG > MG > HG,and the order of simulation accuracy was Horton > Common experienced model > Philip > Kastiakov.Initial infiltration rate,average in-filtration rate,stable infiltration rate and total infiltration during 90 minutes for LG were significantly higher than that for HG.Soil permeability has a significant positive correlation with initial soil water content,total po-rosity,non-capillary porosity,aeration porosity,saturation moisture content,field capacity,available water ca-pacity ,non-capillary porosity water holding capacity,capillary moisture capacity and maximum water-holding capacity.Soil permeability has a significant negative correlation with soil bulk density and insignificant correla-tion with capillary porosity.However,initial infiltration rate has insignificant correlation with initial soil water content,saturation moisture content,available water capacity and capillary moisture capacity.The analysis of regression showed that aeration porosity and available water capacity were main factors restricted infiltration rate.Short-time and light grazing intensity are good for increased of soil moisture holding and water infiltra-tion,and decrease of soil structure degradation.