六盘山半湿润区华北落叶松林土壤含水量的降雨响应

Response of Soil Moisture to Precipitation of Larix principis-rupprechtii Mayr Plantation in a Semi-humid Zone in Liupan Mountains

【目的】研究土壤含水量对不同量级降雨的响应,探讨区域重要人工林树种不同土层土壤含水量与降雨动态变化关系,以加深区域森林生态系统和林地产流的关系理解。【方法】2017年5-10月,同步观测宁夏六盘山半湿润区华北落叶松林根系分布层(0~80 cm)土壤含水量和林外降雨量,比较不同土层土壤含水量对降雨的响应过程。【结果】①2017年华北落叶松生长季降雨主要集中在6月和8月,土壤含水量均值以20~40 cm土层最高,0~10 cm土层最低。生长季内不同月份土壤含水量垂直变化明显;②表层(0~10 cm)土壤含水量与降雨量变化趋势同步,但随着土层深度的增加,土壤含水量与降雨的同步性逐渐减弱。随雨强增加,各层土壤含水量对降雨的响应逐渐明显;③土壤前期含水量高低对不同土层含水量的降雨响应早晚有重要影响。【结论】华北落叶松林下土壤含水量垂直变化对不同量级降雨响应差异明显。

[Objective]Studying the response of soil water content to different magnitude precipitation and discussing the relationship between soil water content in different soil layers of regional important plantations and rainfall dynamics can deepen the understanding of the relationship between regional forest ecosystem and stand runoff.[Methods]From May to October in 2017,the soil water content in the root distribution layer(0~80 cm)of Larix principis-rupprechtii Mayr plantation and the precipitation in the semi-humid region of Liupan Mountains,Ningxia were observed simultaneously.[Results]①The precipitation during the growing season of Larix principis-rupprechtii Mayr in 2017 was mainly occurred in June and August,and the average soil water content was highest in the 20~40 cm soil layer and lowest in the 0~10 cm soil layer.Vertical variation of soil water content was obvious in different months during growing season.②The soil water content of surface soil(0~10 cm)was synchronized with the change of rainfall values,but as the depth of the soil layer increased,the synchronization of soil water content and rainfall gradually weakened.With the increased of rain intensity,the response of soil water content in each layer to rainfall gradually became obvious.③Early soil water content had an important effect on the response of soil moisture content in different layer to rainfall.[Conclusion]The vertical variation of soil water content under the Larix principis-rupprechtii Mayr plantation is significantly different in response to different magnitudes of rainfall.