西双版纳热带季节雨林的粗死木质残体及其养分元素

Coarse woody debris mass and its nutrients stock in tropical seasonal rain forest in Xishuangbanna,Southwest China

对西双版纳热带季节雨林的粗死木质残体及养分元素贮量进行了研究。结果表明,西双版纳热带季节雨林粗死木质残体的贮量为16.2 t·hm-2,约占地上活体生物量的4%左右。其中枯立木占32.5%,倒木占33.2%,倒木残体占12.6%,大枝占21.7%。本研究的粗死木质残体贮量低于巴西和东南亚的热带雨林,处于全球热带雨林的下限。粗死木质残体的氮、磷、钾、钙、镁5种元素的贮量分别为61.8、3.4、30.4、118.3和16.5kg·hm-2。其中倒木所占比例最大,为31.9%～44.8%;枯立木次之(21.5%～28.7%);倒木残体占10.3%～25.5%;3个径级的大枝占14.4%～28.9%。枯立木的C/N、C/P和N/P要高于倒木、倒木残体和大枝。

Based on the investigation at three 1 hm^2 plots, the coarse woody debris （CWD） mass in a tropical seasonal rain forest in Xishuangbanna, southwest China was estimated, with its nutrients stock measured. The CWD mass on the three plots was averagely 16. 2 t·hm^-2, occupying approximately 4% of the living aboveground biomass, among which, snag, fallen tree, fallen tree debris, and large branches accounted for 32. 5% , 33.2%, 12. 6% , and 21.7% , respectively. The CWD mass estimated by this study was lower than that in tropical rain forests in Brazil and Southeast Asia, and its N, P, K, Ca, and Mg stock was 61.8, 3.4, 30. 4, 118.3, and 16. 5 kg·hm^-2, respectively. Fallen tree had the largest proportion of nutrients stock （31.9%-44. 8% of the total）, followed by snag （21.5%-28.7%）, large branches （ 14. 4%- 28.9% ） and fallen tree debris （ 10. 3%-25.5% ）, and snag had higher C/N, C/P and N/P ratios than the others.