我国中东部不同气候带成熟林凋落物生产和分解及其与环境因子的关系

Litter production and decomposition of different forest ecosystems and their relations to environmental factors in different climatic zones of mid and eastern China

在大尺度气候梯度上研究森林凋落物生产分解与气候因子的关系,对于了解森林生态系统碳循环有着重要的作用。在寒温带的黑龙江呼中、温带的吉林长白山、暖温带的北京东灵山、北亚热带的湖北神农架、中亚热带的四川都江堰和浙江古田山,选择典型地带性成熟林,设置72个样地。观测和研究各地点森林凋落物的产量、凋落动态和分解速率,分析三者与环境因子之间的关系,结果表明:不同气候带森林生态系统凋落物年产量为亚热带森林>暖温带森林>温带森林>寒温带森林。随纬度的增加,凋落物产量逐渐减少,凋落物产量与森林类型极显著相关,与年均温显著相关,而与年均降水关系不显著。凋落物生产动态表现为亚热带地区3个类型森林生态系统为双峰型,暖温带、温带、寒温带3个类型森林生态系统为单峰型。凋落物分解速率k表现出了与凋落物产量相似的变化趋势,即随着纬度的增加,分解速率k值逐渐降低,分解速率与年均温极显著相关,与年均降水显著相关。

Production and decomposition of plant litter is one of the most important processes in terrestrial ecosystems. This process could be affected by climate, which elucidates that the spatial patterns and environmental regimes, which regulate the process, are essential to understand the mechanism of ecosystem functioning in both local and broad scales. However, the pattern of the process in large scales along environmental gradients in mid- and eastern China was poorly understood. The aim of the present work was to quantify litter production and its decomposition rate in forest ecosystems from subtropical to temperate zones with a view to gaining further insights into the recycling of above-ground organic matter. Data from 72 plots in six major forest types in China was used to clarify litter production and decomposition in six forest ecosystems and their relations with environmental factors in different climatic zones including Huzhong in Heilongjiang province, Mt. Changbai in Jilin province, Mt. Dongling in Beijing municipality, Mt. Gutian in Zhejinag province, Shennongjia in Hubei province, and Dujiangyan in Sichuan province. The storage of litter fall was in the sequence of： Shennongjia 〉 Dujiangyan〉 Mt.gutian 〉 Mt. Dongling 〉 Mt. Changbai 〉 Huzhong. The annual litter production for Shennongjia, Dujiangyan, Mt.gutian, Mt. Dongling, Mt. Changbai, Huzhong were averaged at 910.98, 830.18, 574.06, 396.19, 374.64, and 249.29 gm-2a-1, respectively. Annual litter fall production was highly significant in relation to forest type and positively related to mean annual temperature, but was not significantly related to mean annual precipitation. There were two litter fall peaks in the subtropical forests in a year, one in spring （from April to May） and the other in autumn （October and November）, while there was just on peak in the cold temperate, temperate and warm temperate forests, which occurred in autumn （from September to October）. The litter decomposition rate （k） was consistent with litter fall production, and the k value decreased with increasing latitude. The annual litter decomposition rate （k） for Shennongjia, Dujiangyan, Mt.gutian, Mt. Dongling, Mt. Changbai, Huzhong were averaged at 0.13, 0.26, 0.36, 0.79, 0.92, and 0.8, respectively. A simple regression model was capable of explaining the majority of climatic effects on litter production and the decomposition rates of various litter types tested in different environments over geographical regions. In conclusion, mean annual temperature is the most important environment variable affecting litter decomposition rate, followed by mean annual precipitation.