中亚热带常绿阔叶林土壤异养呼吸对增温的响应及其机制

土壤异养呼吸是森林生态系统碳平衡主要分量之一，也是森林生态系统碳库损失的重要途径，与净初级生产力共同决定森林碳汇的大小。其微小的变化直接影响全球碳平衡。中高纬度地区增温实验表明，土壤增温将导致土壤异养呼吸增加，而热带、亚热带地区野外增温实验还鲜见报道。本项目拟以中亚热带常绿阔叶天然林红壤为研究对象，通过野外原位模拟土壤增温（埋加热电缆）5℃，以不增温为对照，同时设置保留和去除凋落物处理，采用多通道土壤碳通量长期自动观测系统，对各处理异养呼吸和矿质土壤呼吸（壕沟法）进行高频观测，通过野外原位收集凋落物DOM和定期采集土壤样品，从土壤微生物学（PLFA技术）角度，探讨土壤异养呼吸对增温的响应及其机制。研究结果对深入理解全球变暖对森林生态系统的影响具有重要科学价值，对完善全球碳循环模型具有重要意义。

Heterotrophic respiration is one of important component of the forest ecosystem carbon balance, and plays an important role in forest ecosystem carbon losses. Together with the net primary productivity, heterotrophic respiration determine capacity of forest carbon sinks. Minor changes in the rate of heterotrophic respiration could impose a great impact on future atmospheric CO2 concentrations. Many studies have shown that soil warming increased the heterotrophic respiration in mid- to high- latitude ecosystems. However, there are few reports on in situ soil warming experiments at low latitudes. We conduct a soil warming manipulation experiment in an evergreen broad-leaved forest in mid-subtropics, and heating cables are used to enhance soil temperature by 5 °C. At the mean time litter addition and exclusion treatments are set up. The multiple channel automated chamber system aimed for high temporal frequency measurements is aslo employed to assess how heterotrophic respiration and its components are affected by warming. Furthermore, with collecting litter DOM and soil sampling regularly in situ, we tend to understand the effect of warming on heterotrophic respiration and reveal its microbial mechanism with PLFA technique. This project is of great significance in better evaluating the response of forest ecosystem to global warming, and improving forest carbon cycling model.