西宁市不同密度青杨人工林土壤水分对降雨的响应研究

Response of Soil Moisture of Populus cathayna Rehd.Artificial Forests With Different Densities to Rainfall in Xining City

为揭示西宁市不同密度青杨人工林对降雨的响应规律,以西宁市南北山青杨人工林为研究对象,连续监测0~50 cm深土层土壤含水量及降雨量,对其0~50 cm深土层中土壤水分动态变化进行分析。结果表明:①不同密度林地0~10 cm深土层均为弱利用层,低、中密度林地40~50 cm深土层均为调节层,低密度林地利用层最深;②不同深度土层中土壤含水量对降雨的响应分别为了小雨(10~20 cm深土层)、中雨和大雨(20~30 cm深土层),小降雨事件(<10 mm)仅能对0~20 cm深土层中土壤水分进行补给,对深层土壤水分补给较弱;③除0~20 cm深土层外,中密度林地的土壤含水量高于低、高密度林地,大雨条件下低密度林地0~30 cm深土层中土壤水分在雨后第一天呈现跳跃式上升,但在之后逐渐下降,而中、高密度林地在雨后第一天土壤水分上升较快,在之后呈现小幅度上升的趋势;④不同密度林地到达土壤表层的水分不同,土壤含水量比较为:中密度林分>低密度林分>高密度林分。研究结论可为西宁地区的水土流失治理提供参考。

In order to reveal the response law of Populus cathayna Rehd.artificial.forests of different densities in Xining City to rainfall,the Populus cathayna Rehd.artificial forests in North and South Mountain of Xining City were taken as the research object,and the soil moisture content of 0~50 cm soil layer and rainfall were continuously monitored,and the dynamic changes of soil moisture in 0~50 cm soil layer were analyzed.The results showed that:①0~10 cm of soil in different density forests is a weak utilization layer,40~50 cm soil layer in low and medium density forests is a regulating layer,and the utilization layer in low density forests is the deepest.②The response of soil moisture content to rainfall in different soil layers reached 10~20 cm for light rainfall,20~30 cm for medium rainfall and heavy rainfall,respectively,and small rainfall events(<10 mm)only recharged soil moisture in the 0~20 cm soil layer,and weakly recharged the deeper soil moisture.③Except for the 0~20 cm soil layer,the soil moisture content of medium-density woodland was higher than that of low and high-density woodland.Under heavy rainfall conditions,soil moisture in the 0~30 cm soil layer of low-density woodland showed a jumping increase on the first day after rainfall,but gradually declined thereafter,whereas in medium-and high-density woodland,the soil moisture increased more rapidly on the first day after rainfall,and then showed a small upward trend thereafter.④The moisture reaching the soil surface was different in different densities of woodlands,and the soil moisture content from high to low was medium-density stands>low-density stands>high-density stands.The conclusions of this study can provide theoretical basis for soil erosion management in Xining area.