中国森林生态系统凋落叶分解速率的分布特征及其控制因子

凋落物分解是森林生态系统碳循环的重要组成部分。建立中国森林凋落叶分解速率数据库, 分析凋落叶分解速率与其主要影响因素之间的关系, 对精确地预测中国森林生态系统碳收支具有重要意义。该研究通过收集已报道的中国森林凋落叶分解常数(k)及其相关变量, 分析探讨地理因素(纬度、经度和海拔)、气候因素(年平均气温和年降水量)、凋落叶质量(氮、磷、钾、木质素、木质素:氮和碳氮比)和叶特性(常绿与落叶、阔叶与针叶)对中国森林凋落叶分解速率的影响。结果表明, 在国家尺度上, k随年平均气温、年降水量、氮、磷和钾的增加而增加, 随纬度、经度、海拔、碳氮比、木质素和木质素:氮的增大而减小, 叶特性对k的影响不显著。气候与地理因素(年平均气温、年降水量和纬度)能解释k值变异的34.1%, 凋落叶质量(氮、钾、木质素和木质素:氮)能解释k值变异的21.7%, 它们能共同解释k值变异的74.4%。了解森林凋落叶分解速率在国家尺度上的格局和主控因素可为中国森林生态系统碳循环相关模型提供基础参数。

Spatial characteristics in decomposition rate of foliar litter and controlling factors in Chinese forest ecosystems

Aims We aim to construct a national database for decomposition rate of forest foliar litter and to investigate the effects of controlling factors concerning geography (i.e. latitude, longitude, and altitude), climate (i.e. mean annual temperature and mean annual precipitation), and litter quality (i.e. the concentrations of N, P, K, and lignin, C:N ratio, and lignin:N ratio) on litter decomposition.Methods We compiled a large dataset on decomposition constant (i.e. k value, which indicates the rate of litter decomposition) for foliar litter in Chinese forest ecosystems covering 74 study sites, and conducted simple and multiple regression analyses to explore the relationships of the k value with the controlling factors at the national scale.Important findings The k value showed a tendency to decrease with latitude, longitude, altitude, lignin content, C:N, and lignin:N of litter, and to increase with mean annual temperature, mean annual precipitation, and litter nutrient concentrations (N, P and K) at the national scale. Single factors such as climate, litter quality, and geographic variable only explained 0.1%-30.3% of the variation in the rate of litter decomposition. However, a combination of climatic factors (mean annual temperature and mean annual precipitation) and latitude accounted for 34.1% of the variation in the rate of litter decomposition. Similarly, a combination of N, K, lignin, and lignin:N accounted for 21.7% of the variation in the rate of litter decomposition. Altitude, mean annual temperature, mean annual precipitation, N, K, and lignin:N collectively accounted for 74.4% of the variation in the rate of litter decomposition. Our results suggest that climate is the most important regulator of litter decomposition at the national scale and that the effects of litter quality is relatively small compared to climate.