青海北部草地水分时间异质性及主导因素

Temporal Heterogeneity and Dominant Factors of Soil Water Content in the Grassland in the Northern Qinghai Province

为探索青海北部草地土壤水分的时间异质性特征,采取小区定位监测的方法,获取典型草地2009-2012年生长季(4-9月)根区(0-0.7 m)土壤水分数据,采用经典统计学和地统计学方法,分析了土壤水分的时间变异特征。结果表明:青海北部紫花针茅(Stipap urpurea)草地根区土壤含水量的时间变异程度随深度的增加而降低,并通常保持在中等变异程度。半方差函数模型对土壤含水量时间变异拟合度较高,2011年生长期土壤含水量的时间异质性最高,2012年最低。研究区土壤含水量时间变异程度主要受土层深度、植被盖度和降水量的影响,对其时间变异的解释度达到51.5%。研究结果对于深入认识青海草地生态系统土壤水分的时间异质性、增强宝贵土壤水分的科学管理具有一定的科学和实践意义。

In order to explore the temporal heterogeneity of soil moisture in the grassland of the northern Qinghai Province,a cell location monitoring experiment was adopted.Soil water content of root zone(0-0.7 m)in typical grassland in the growing season(April to September)from 2009 to 2012 was obtained and the temporal heterogeneity of soil moisture was analyzed by classical statistics and geostatistics methods.The results showed that the temporal heterogeneity of soil water content in 0-0.7 m layer of Stipap urpurea in the northern Qinghai Province decreased with increase of depth,and the variability of soil water content usually remained at moderate degree;semi-variogram model had a high degree of fitness for soil water content temporal heterogeneity;the temporal heterogeneity of soil water content in grassland was the highest in 2011 and the lowest in 2012;the temporal variability of soil water content in the study area was mainly affected by soil depth,vegetation coverage and precipitation;the three controlling factors together explained the time variation of soil water content by 51.5%.These results have the scientific and practical significance for understanding the temporal dynamic characteristics of soil water content and enhancing the scientific management of valuable soil moisture in the grassland ecosystem of the Qinghai Province.