枝条覆盖对半干旱黄土丘陵区平茬柠条林地土壤水分的影响

为了研究枝条覆盖对林地土壤水分的影响,提高土壤水分利用效率。2013年5—9月,以半干旱黄土丘陵区平茬柠条林为对象,采用中子水分仪对未覆盖和枝条覆盖林地土壤水分进行定位观测,研究了枝条覆盖对林地土壤水分的影响。研究期间共观测到降雨28次,总降雨量达495.9 mm。未覆盖和覆盖林地降雨补给量与降雨量之间均呈极显著正相关关系。枝条覆盖使林地降水入渗补给系数由0.50增加至0.70,明显提高了林地次降水补给量和入渗深度。覆盖林地各月土壤水分消耗量均高于对照林地,整个生长季,前者比后者多消耗了37.56 mm土壤水分,仅相当于所增加的降雨补给量的1/3。在丰水年,覆盖一直表现出对林地土壤水分的正效应,剖面0—260 cm范围内土壤水分条件有明显改善。

Effects of branch mulch on soil water of pruned Caragana korshinskii forestland in the semi-arid Loess Hilly Region

In the semi-arid Loess hilly region where there are insufficient water resources, the condition of soil water is the most important factor limiting plant growth.Studies have shown that biological mulching can effectively increase rainfall infiltration depth and reduce surface runoff, as well as reduce invalid evaporation from the soil surface.However, most studies on biological mulching technologies focused on straw and grass mulching, and there is a lack of information on the effect of branch mulching, particularly in pruned Caragana korshinskii forestland. In the semi-arid Loess hilly region, soil drying is a serious environmental problem in artificial C. korshinskii forestland. The positive effects of branch mulching on soil water conditions may have great significance for vegetation restoration and ecological construction. To understand these effects and to apply the technology for increasing soil water use efficiency, we measured volumetric soil water content (VSWC) using a neutron probe in mulched and unmulched shrubland,of pruned C. korshinskii from May to October 2013. Twenty-eight rainfall events were observed during the period and the total rainfall amounted to 495.9mm. Approximately 60% of rainfall events were less than 10mm, and the maximum rainfall was 90.3mm. Regression analysis showed significant positive correlations between rainfall and recharge amounts in both mulch plots and control plots. Furthermore, branch mulch increased the recharge amount. However, when the rainfall was less than 3.1mm, the recharge amount of soil water in mulched shrubland was less than unmulched shrubland. In addition, branch mulch increased the infiltration depth of rainfall, and the rate of rainwater harvesting was improved from 0.50 to 0.70. When the rainfall was >9.4mm, the recharge depth of soil water in unmulched shrubland was less than mulched shrubland. At the same time, there was more evapotranspiration in mulch plots than in control plots. During the growing season, total water consumption in mulch plots was 37.56mm greater than in control plots, which was merely 1/3 of the rainwater more infiltrated because of mulching management. Therefore, there was a positive effect of branch mulch on soil water resources in the wet years, reflected as the increase of soil water content in the 0-260cm depth profile. This study demonstrated that branch mulching can substantially increase the infiltration depth and recharge amount of rainfall in pruned C. korshinskii forestland and improve the utilization rate of rainwater.