青海湖流域芨芨草斑块对地表水分再分配过程的影响

Effects of Achnatherum Splendens Patchy on Redistribution of Surface Water Flow in Qinghai Lake Watershed

[目的]研究芨芨草斑块对降雨再分配和地表径流过程的影响,为揭示植被斑块的形成与水分调控机理提供依据。[方法]以青海湖流域芨芨草斑块为例,通过对芨芨草斑块冠层降雨再分配和地表径流进行试验观测,计算水平方向芨芨草斑块水分补偿比例。[结果](1)芨芨草斑块穿透雨占降雨量比例为70.58%,穿透雨主要受降雨量、降雨强度和降雨历时的影响,芨芨草斑块冠层对降雨再分配过程的影响和多数干旱区灌木相似;(2)芨芨草斑块平均径流系数为0.45%±0.33%,明显低于基质区(2.08%±1.46%),且随着降雨量增加而呈增大趋势;(3)芨芨草斑块水分补偿比例为1.13%±1.34%,且随着降雨量和降雨强度增加而增大,最高可达到4.94%。[结论]在生态系统尺度,芨芨草斑块会受到来自基质区的径流补偿,这是斑块植被一种适应干旱的水分调控策略。

[Objective]The impacts of Achnatherum splendens patches on rainfall partitioning and surface runoff were studied to provide a basis for revealing the formation of vegetation patches and the mechanism of water regulation recognition.[Methods]The deep-rooted grass of A.splendens was used in the Qinghai Lake watershed as an indicator plant to calculate the water compensation ratio of A.splendens patches in the horizontal direction by observing the redistribution of rainfall and surface runoff in the crown of A.splendens patches.[Results]①The throughfall of the A.splendens patch accounted for 70.58%of the total rainfall and was mainly affected by rainfall,rain intensity,and duration.This was similar to most shrubs in arid ecosystems.②The mean runoff coefficient of the A.splendens patch was 0.45%±0.33%.This was significantly lower than that of the matrix(2.08%±1.46%)and increased with rainfall.③The water compensation of the A.splendens patch accounted for 1.13%±1.34%of total rainfall,and it increased with rainfall and rain intensity.The highest value of the proportion of water compensation was 4.94%.[Conclusion]The A.splendens patch can be recharged by the runoff from the matrix in the ecosystem scale,which is the water regulation mechanism of drought adaptation for patchy vegetation in arid regions.