南方水土流失区马尾松对降雨再分配的影响

Effects of Pinus massoniana in soil erosion area in South China on rainfall redistribution

以南方典型水土流失区福建省长汀县河田镇36株马尾松为研究对象,连续观测2018年5—11月林外降雨量、穿透雨和树干茎流。研究穿透雨、树干茎流、冠层截留与降雨量、降雨强度关系,并将降雨数据与胸径、树高、冠幅、叶面积指数进行相关性分析和拟合,研究其对降雨再分配的影响。结果表明:共观测降雨事件90次,累计林外降雨量1191.0 mm,穿透雨量1018.7 mm,冠层截留量156.9 mm,树干茎流量15.4 mm,穿透雨量、冠层截留量、树干茎流量分别占累计降雨量的85.53%、13.17%和1.29%。降雨量、降雨强度与降雨再分配显著相关且拟合效果好;由拟合方程计算可知,当降雨量>1.53 mm时产生穿透雨,降雨量>2.82 mm时产生树干茎流。叶面积指数LAI与穿透雨量、冠层截留为对数函数关系,冠幅与树干茎流量呈指数函数关系。

[Background]Changting county in Fujian province is one of the most severely eroded granite red soil counties in southern China.Rainfall kinetic energy is the direct driving force of soil erosion in the southern red soil area,and it is also the main cause of soil erosion.Studying the rainfall redistribution characteristics of Pinus massoniana in Changting county of Fujian province will provide a theoretical basis for soil erosion control.[Methods]Taking 36 P.massoniana in Hetian town,a typical southern soil erosion area,as the research object,we continuously observed the rainfall,throughfall,and stem flow outside the forest from May to November 2018.The relationship between throughfall,stem flow,canopy interception and rainfall,rainfall intensity were studied,and the correlation analysis and fitting of rainfall data with DBH(diameter at breast height),tree height,crown width,and LAI(leaf area index)were carried out to study the impact on rainfall redistribution.A total of 90 rainfall events were observed.[Results]1)The cumulative rainfall outside the forest was 1191.0 mm,the throughfall was 1018.7 mm,the canopy interception was 156.9 mm,and the stem flow was 15.4 mm.2)The throughfall,canopy interception,and stem flow accounted for the cumulative total 85.53%,13.17%and 1.29%of rainfall.3)Rainfall and rainfall intensity were significantly correlated with rainfall redistribution and had a good fitting effect.From the calculation of the fitting equation,it can be seen that throughfall was generated when the rainfall exceeded 1.53 mm,and the stem flow was generated when the rainfall exceeded 2.82 mm.4)LAI had a logarithmic function relationship with penetrating rain and canopy interception,and canopy width had an exponential function relationship with stem flow.[Conclusions]By observing the rainfall of the P.massoniana forest in the typical soil erosion area in the South China,the redistribution characteristics of the P.massoniana rainfall are obtained,and scientific guidance is provided for the management of the P.massoniana forest in the soil erosion area.