九寨沟不同类型森林群落凋落物分解的研究

利用网袋法对九寨沟主要森林类型的凋落物的分解作用进行了研究.结果显示,九寨沟各林型凋落物的分解率k以白桦林最高,达0.7864,巴山冷杉林最低,为0.2705.九寨沟6个主要类型群落中,除巴山冷杉林的年分解率为23.70%,与一般温带针叶林分解率相似外,其余皆在30.20%至54.45%之间,高于温带森林凋落物的平均分解速率20%～30%.在实验期内五次取样的失重率与时间的关系有两类,它们以海拔2400m为界.在海拔2400m以下的白桦林、青杆林和油松林群落中,凋落物的失重率变化呈S形;在海拔2400m以上的辽东栎林、红桦林和巴山冷杉林群落中,凋落物的失重率变化呈山字形.这6种类型森林群落凋落物的分解作用受多种因素影响.一般地,海拔相同时阔叶林群落凋落物分解比针叶林群落快.

A Study of Litter Decomposition of Various Forest Communities at the Jiuzhaigou Valley

A study of litter decomposition in temperate forestsat the Jiuzhaigou Valley was conducted using the litter bag method during a one-year period. Decomposition rates and their seasonal dynamics of six locally dominant forest community types, i.e. Quercus liaotungensis , Betula platyphylla , Betula albo-sinensis , Pinus tabulaeformis, Abies fargesii and Picea wilsonii, were measured. The results show that the instantaneous fractional loss rates, k, range from 0. 2705 to 0. 7864. Except for annual decomposition rate of the Abies fargesii forest community, which is roughly equal to that of temperate needle forest community, each of the other five is higher than the mean value of annual decomposition rate of temperate forest communities. Litter decomposition of 6 frorest communities shows two patterns. Litter decomposition of the forest communities below 2400m, including Picea wilsonii, Betula platyphylla, and Picea wilsonii community, shows a sigrnoid pattern, while that of the other communities above 2400m, shows a normal-curve-like pattern. Factors Influencingde composition varyat different experimental sites. Generally, the decomposition rate of hardwood litter is higher than that of the conifer litter at the same elevation.