黄土丘陵区2种典型林分降雨分配特征及其主要影响因素

Characteristics and Main Influencing Factors of Rainfall Partitioning in Two Typical Forests in the Loess Hilly Region

森林对降雨的分配是森林生态水文和生物地球化学循环中的重要过程之一。通过对黄土丘陵区2种典型林分(刺槐林和辽东栎林)生长季降雨分配过程的实地监测,探究2种林分的降雨分配特征及其主要影响因素。结果表明:试验期间,刺槐林和辽东栎林降雨分配各组分均表现为穿透雨量(325.0,295.1 mm)>冠层截留量(39.8,73.6 mm)>树干径流量(25.8,21.9 mm),同时穿透雨率(83.2%和75.6%)>冠层截留率(10.2%和18.8%)>树干径流率(6.6%和5.6%)。次降雨量是影响降雨分配的关键因子,穿透雨量和树干径流量与次降雨量间呈现极显著线性关系,冠层截留量与次降雨量间呈现极显著对数函数关系;穿透雨率和树干径流率与次降雨量间呈现显著对数函数关系,冠层截留率与次降雨量间呈现极显著指数函数关系。刺槐林和辽东栎林产生穿透雨的次降雨阈值分别为1.0,1.3 mm,产生树干径流的次降雨阈值分别为5.9,5.4 mm。刺槐林产生的穿透雨量和树干径流量均大于辽东栎林,而冠层截留量小于辽东栎林。研究结果为黄土丘陵区森林生态水文过程的研究提供基础数据,对该地区植被恢复过程中植被类型的选择具有指导意义。

Rainfall partitioning by forests is one of the important processes in forest eco-hydrological and biogeochemical cycles.In this study,the characteristics and main influencing factors of rainfall partitioning of two typical forest types(Robinia pseudoacacia plantation and Quercus liaotungensis natural secondary forest)were investigated by field monitoring during the growing season in the loess hilly region.The results showed that during the experiment,the components of rainfall partitioning in R.pseudoacacia plantation and Q.liaotungensis forest were in the order of throughfall(325.0 and 295.1 mm)>canopy interception(39.8 and 73.6 mm)>stemflow(25.8 and 21.9 mm),and throughfall rate(83.2% and 75.6%)>canopy interception rate(10.2% and 18.8%)>stemflow rate(6.6% and 5.6%).Rainfall amount was the key factor affecting rainfall partitioning.A highly significant linear relationship was observed between throughfall and stemflow and rainfall amount,while the relationship between canopy interception and rainfall amount exhibited a highly significant logarithmic function.A significant logarithmic relationship existed between throughfall rate and stemflow rate and rainfall amount,while a highly significant exponential relationship was found between canopy interception rate and rainfall amount.Throughfall processed when rainfall exceeded 1.0 and 1.3 mm for R.pseudoacacia plantation and Q.liaotungensis forest,respectively.Stemflow processed when rainfall exceeded 5.9 and 5.4 mm for R.pseudoacacia plantation and Q.liaotungensis forest,respectively.The throughfall and stemflow generated by R.pseudoacacia plantation were larger than that of Q.liaotungensis forest,while the canopy interception was smaller than that of Q.liaotungensis forest.This study provides basic data for the research of eco-hydrological processes in the loess hilly region,and has guiding significance for the selection of vegetation types in the process of vegetation restoration in this area.