毛乌素沙地杨柴灌木林土壤水分对不同降雨格局的响应

Response of Soil Moisture to Different Rainfall Patterns in Hedysarum Leave in Mu Us Sandy Land

[目的]研究不同降雨格局下,土壤水分的动态变化特征,对判断群落结构的稳定性和为群落结构进行优化调控提供理论依据。[方法]选择毛乌素沙地典型飞播杨柴灌木林地不同深度土壤为研究对象,使用Watchdog自动水分监测系统连续监测不同深度土壤水分含量动态变化,研究不同降雨事件下10,30,50,70,90和110 cm土层水分的时空变化,分析土壤水分入渗、再分配及水分补给特征。[结果]①杨柴群落0—110 cm深度土壤水分含量变化受降雨的影响具有明显的垂直特征,10 cm深度土层为变化剧烈层,30 cm深度土层为弱变化层,50 cm以下深度土层为稳定层。②10 cm深度土壤水分对降雨和温度的响应明显,降雨强度和土壤初始含水量对浅层土壤的补给影响较大同时对入渗的深度有一定影响。30 cm以下土层随着深度的增加对降雨的响应滞后,30—50 cm土层主要受初始含水量和降雨量影响较大,50 cm以下深度水分变化主要受降雨量的影响。③>8.8 mm的降雨对10 cm及以下土层具有补给作用,>40 mm的降雨量可通过降水再分配至少达到110 cm深度土层。[结论]杨柴群落根系主要分布在0—40 cm深度处,>8.8 mm降雨可供杨柴群落有效利用,>40 mm的降雨量可有效对地下水进行补给,有利于群落结构的稳定性和应对下一年度植被生长初期需水时降雨量较小的干旱月份。

[Objective]The dynamic change characteristics of soil water under different rainfall patterns were studied,in order to provide theoretical basis for judging the stability of community structure and optimizing the community structure.[Methods]Taking the soil of different depths in typical aerial seeding Hedysarum leave shrub land in Mu Us sandy land as the research object,The watchdog automatic water monitoring system was used to monitor the dynamic change of soil moisture content in different depths continuously.The temporal and spatial changes of soil moisture in 10,30,50,70,90 and 110 cm soil layers under different rainfall events were studied,and the characteristics of soil moisture infiltration,redistribution and water supply were analyzed.[Results]①The change of soil moisture content in 0—110 cm depth of Hedysarum leave community was affected by rainfall,and had obvious vertical characteristics.The soil water content in 10 cm depth was changed greatly,that in 30 cm depth was changed weakly,and that in 50 cm depth was stable.②The soil moisture at the depth of 10 cm showed an obvious response to rainfall and temperature.The rainfall intensity and initial water content showed a greater impact on the recharge of shallow soil and a certain impact on the infiltration depth.The response of the soil layer below 30 cm to rainfall lagged behind with the increase of depth.The soil layer between 30 to 50 cm was mainly affected by initial water content and rainfall,while the change of water content below 50 cm was mainly affected by rainfall.③The rainfall of>8.8 mm had replenishment effect on the soil layer of 10 cm and below,and the rainfall>40 mm could reach at least 110 cm soil depth through precipitation redistribution.[Conclusion]The root system of Hedysarum leave community is mainly distributed at 0—40 cm soil layer.The rainfall of>8.8 mm can be effectively used by poplar and firewood community.The rainfall of>40 mm can recharge groundwater effectively,which is conducive to the stability of community structure and coping with the dry months with less rainfall in the early stage of vegetation growth in the next year.