Hydrochemical Characteristics and Their Regression Analysis on the Secondary Rain Forest Ecosystem of Tropical Upland in China

As part of the systematic study, the element contents in rainfall, throughfall, stemflow, surface flow and stream were measured from October 1990 to October 1991 at the secondary rain forest catchment of tropical upland in Jianfengling,Hainan Island,China. The hydrochemical properties and migratory changes of nutrient in the hydrochemistry system were studied and analyzed by the method of small catchment and orientation observation. Element contents of the throughfall and stemf low increased by 0.43~15.1 and 0.26~24.7 times more than that of the precipitation respectively. Except Ca, Si and Al, the elements of stream were less than that of the through-fall. The output contents of Ca and Si were more than the input of both. It is pointed out that the rainfall and throughfall are an input source of the hydrochemical elements of the secondary rain forest ecosystem of tropical upland. The system not only has stornger hydrochemical regulating function but also has the function of chemical filtration, uptake and store. Moreover, multivariate linear models have been established between each element content and the characteristics factors of precipitation in throughfall, stem-flow, stream.