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

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 1 191.0 mm, the throughfall was 1 018.7 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.