两种中国特有树种的枯叶分解速率

银杏和水杉是我国特有的珍贵树种。本文对北京公园内银杏和水杉林下的枯叶分解速率进行了试验研究。枯叶失重率：放置380天的银杏为55.63%；放置338天的水杉为53.39%。用指数衰减模型估算枯叶的年腐解率，银杏为0.771克／(克·年)；水杉为0.824克／(克·年)。根据枯叶的化学成分分析表明，枯叶的失重率和枯叶化学成分净丧失值的变化趋势相一致。枯叶在一年的分解过程中，碳、氮含量比值随时间的推移而下降。

THE LITTER DECOMPOSITION RATES OF TWO ENDEMIC TREE SPECIES OF CHINA

Ginkgo biloba and Metasequoia glyptostroboides are two endemic tree species of China. In this paper, the decomposition rates of their litter placed under Ginkgo and Metasequoia forests in the parks in Beijing have been studied. The weight loss rate of the ginkgo litter placed under ginkgoes for 380 days was 55.63% and that for the metasequoia litter placed under metasequoias for 338 days was 53.39%. The exponential decay model was used and the annual decay rate of litter was estimated to be 0.771 g/(g·year) for the Ginkgo, and 0.824 g/(g·year) for the Metasequoia. Analysis of the chemical composition change in the litter showed that the changing tendency of the weight loss rate was in agreement with the net loss of the chemical composition in the litter. During the annual decmoposing process, the ratio of the carbon content and the nitrogen content of the litter decreased with the passage of time.