中国天然林凋落物量的空间分布及其影响因子分析

Spatial pattern and environmental controls of annual litterfall production in natural forest ecosystems in China

森林凋落物是森林生态系统物质循环和能量流动中的重要结构和功能单元,具有不可替代的生态学作用,我国在森林凋落物方面已经开展了大量研究工作,但全国大尺度范围内森林凋落物的综合性研究还很少见报道.本研究收集整理了1970-2014年发表的308组中国天然林年凋落物量数据,观测地点分布范围为北纬18°15′-51°30′,东经82°53′-129°06′,海拔0-3828 m,涵盖了中国主要森林类型.研究表明,从寒温带、温带、亚热带到热带,中国天然林年凋落物量呈逐渐增加趋势,平均值分别为2.45,3.56,6.66和9.30 t hm-2.凋落物随着纬度升高呈明显下降趋势,纬度每升高1°,森林年凋落物量下降0.19-0.27 t hm-2.在全国尺度上天然林年凋落物量主要受热量因子调控,等效纬度（综合考虑了纬度与海拔的影响）和年均温均可以解释年凋落物量约60%的变化情况,随着凋落物量观测时间延长其相关性进一步得到提高,如2或3年以上观测时长的解释率分别提高约11%和15%.本研究结果可为森林生态系统管理与林火预测提供森林凋落物的定量参考.

Litterfall is an important structure and function unit of nutrient cycling and energy flowing in forest ecosystems. A large number of litterfall studies have been developed in Chinese forests, however, few synthesis studies at the national scale have been reported so far. In this paper we synthesized 308 litterfall datasets during the period of 1970–2014 in Chinese natural forests. The observation sites of those datasets distributed widely in various climate zones with latitudes 18°15′–51°30′N, longitudes 82°53′–129°06′E and altitudes 0–3828 m. The annual litterfall production increased from boreal, temperate, subtropical to tropical forests, the mean values were 2.45, 3.56, 6.66 and 9.30 t hm-（-2）, respectively. There was significantly negative correlation between annual litterfall production and latitude（R2=0.434）. The annual litterfall production decreased by 0.19–0.27 t hm-（-2） with latitude increasing 1°. Annual litterfall production was mainly influenced by heat factors, for example, equivalent latitude（the interaction bewteen latitud and altitude） and mean annual temperature, which could both explain approximately 60% of the variation in Chinese natural forests. We found that the relationships would be further improved by 11% or 15% when the observation periods were more than 2 or 3 years, respectively. The results would provide forest ecosystem management and forest fire prediction with quantitative reference of forest littlefall.