A PRELIMINARY STUDY ON CHANGE OF NUTRIENT IMPORT AND EXPORT IN THE PROCESS OF RAINFALL IN THE AILAOMOUNTAINS REGION OF YUNNAN PROVINCE
云南哀牢山大气降雨过程中养分输入及输出变化的初步研究

In this paper, the effects of rainfall on nutrient import and export in the broad-leaved evergreen forest in southwest Yunnan Province have been observed. The results show that in the proress of rainfall the nutrient import in rainfall is mainly N and the major elements of nutrient import in throughrain are P,K and Mg. They orcupy 69.85%, 77.33%, 98.19%,and 80.40% of the total nutrient import respectively. Ca occupies about half of the total nutrient import in rainfall and throughrain and the percentages are 45.35% and 54. 38%respectively. The major form of nutrient export is soil percolation. N, P, K, Ca and Mg occupy 96. 52%, 86.79%, 69.13%, 98.17% and 97.21% of the total nutrient export respectively. In nutrient cycle,N, P, K and Ca increase 15. 94kg/ha. a, 0. 353kg/ha. a,3. 83kg/ha. a, 1. 26 kg/ha. a. respectively,but Mg reduces 0. 654 kg/ha. a.