树木自然死亡和各种干扰产生的倒木是森林生态系统碳库的重要组成部分，其分解释放的CO2是生态系统碳收支中不容忽视的一个组分。但目前对倒木分解碳释放的机制尚不明确，特别是对中亚热带水分条件下倒木分解的驱动机制研究较为缺乏。本项目选择江西为中亚热带代表区域，开展典型森林类型（常绿阔叶林、杉木林、马尾松林）倒木在不同温度区的原位分解、光强以及光质模拟调控试验、倒木交互置换野外控制试验，通过监测倒木分解质量损失及其CO2释放、微生物群落特征、结构性组成与物理结构的变化，以阐明中亚热带湿润气候区倒木分解碳释放规律，揭示中亚热带区倒木分解碳释放的温度、光照等环境因子、基质、微生物驱动机制，探讨倒木分解"主场效应"及光降解效应及其机制。为进一步量化倒木分解碳释放对森林生态系统碳平衡的影响提供理论依据，对科学、准确估算中亚热带森林碳源/汇和林地倒木科学管理有重要意义。

Fallen trees caused by chronic mortality and various forest disturbances is an important component for carbon budget in terrestrial forest ecosystems. There is an important research need to understand the mechanisms or factors responsible for CO2 release during long-term decay of fallen trees, particularly in mid-subtropic forests. In this proposed study, I will select major typical forests including evergree broadleaved forests, Chinese fir forests and massonia forests located in Jiangxi Province to study how CO2 is released from fallen trees. The study methods include down wood decay experiments in different temperature zones, controlling experiements using various simulated light intensities and types, and field experiments using reciprocal fallen trees transplanting. During these experiments, data on biomass loss, CO2 release, microbial communities, structural components and physical structures of fallen trees will be carefully monitored and collected. Our objectives are to understand how CO2 is released over fallen trees decay course and what factors (temperature, light, substrates and microbial communities) are driving mechanisums for C releases, and to explore fallen trees decay under the conditions of "Home-field Advantage" and photodegradation. Our ultimate goal is to quantify the contribution of fallen trees to forest ecosystem C budget and to support designing of suitable fallen trees management strategies.