Carbon Budget of Forest Ecosystems and Its Driving Forces

森林在区域和全球碳循环中起着关键作用，研究森林碳循环各分量的变化对估算区域碳收支和制定应对气候变化的森林管理政策有重要意义。本文从中国、东亚区域及全球尺度就森林碳源汇特征及其机制的最新研究进展进行评述。近30年来我国森林生物量碳汇1896TgC（TgC＝1012gC），年均增加70．2TgC／yr。最近10年，森林碳循环的所有组分（生物量碳、凋落物碳、木质残体及土壤有机碳）均表现为明显的碳汇，年总碳汇186．7 TgC／yr。在东亚区域尺度，对1970 s—2000 s森林林分的碳储量及其碳源汇变化的研究表明，东亚森林整体为显著的碳汇，但朝鲜和蒙古国为碳源；东亚地区的碳汇主要来自中国，其次是日本。中国森林碳汇增加主要源自人工林面积增加的贡献，而日本和韩国则主要来自于森林的再生长。在全球尺度，对不同气候带森林生态系统碳收支全组分碳储量及其变化的分析揭示，全球森林是一个显著的碳汇。在过去的近20年里，全球森林每年固定约4．0PgC，相当于抵消了同期化石燃料碳排放的一半。Forests play an important role in regional and glob-al carbon ( C ) cycles.Quantitative estimation of com-ponents of forest C budget and their spatial and temporal distributions is both of scientific and of political impor-tance.Here we provide a brief review of update findings of forest C budgets and mechanisms at spatial scales of national, regional and global.In general, China's for-ests have biomass C sink of 1896 Tg during 1977—2008, with an annual C sink of 70.2TgC/yr.All sec-tors ( biomass, plant residue, litter and soil) of forest C pool shows significant C sink, with a total sequestration rate of 186.7TgC/yr, in recent ten years.The biomass C stocks of the forests in East Asian increased as a whole over 1970s—2000s.China and Japan were two major contributors to the total region's forest C sink while the reduction in forest land in both North Korea and Mongolia caused a C loss.In China, the areal ex-pansion of planted forest land was a larger contributor to C sinks than increased biomass density.On the contra-ry, forests in Japan and South Korea acted as a C sink because of increased forest growth rather than area in-crement.Globally, a total forest sink of 4.0PgC was es-timated based on forest inventory data and long-term e-cosystem carbon studies for 1990 to 2007 .The total car-bon sequestration by world forests offset half of its con-temporary fossil-fuel CO2 emissions.研究资助全球变化研究国家重大科学研究计划(2010CB950600)。中国科技核心期刊(ISTIC)320-2