多年冻土退化对大兴安岭泥炭地碳排放与输出过程的影响机理研究

Permafrost degradation had significantly influenced the soil environments and carbon cycle in the peatlands. However, there are still lots of unknowns and uncertainties. The researches about the carbon cycle of permafrost peatlands are week in the Great Hing'an Mountains, which are very sensitive to the climate change. The project aims to select the permafrost peatlands in this area. Through the field observations, stimulated temperature, analysis in the room and incubation experiments, we want to show the rates of permafrost degradation and the soil carbon accumulation rates. We study the effects of permafrost degradation on CO2 and CH4 fluxes, the carbon gases emissions from the soil to the atmosphere, the output of soil dissolved carbon, the decompositions of different soil carbon pools, enzyme activities and microbial activities. The results of the project could show the response mechanisms of different soil carbon pools on environment changes (thaw process, freeze-thaw cycle, increased temperature, nitrogen changes, aerobic and anaerobic environments) during the permafrost degradation. We also discuss the potential effects of permafrost degradation on peatlands carbon emissions and organic carbon output. This study could be helpful to accurately assess the trends of carbon cycle process under global change in the peatlands and provide theoretical basis and data support.

多年冻土退化对泥炭地土壤环境和碳循环有着非常重要的影响，但目前的研究还有诸多未知之处和不确定性，而对全球变化响应敏感的大兴安岭多年冻土区泥炭地相关研究还十分有限。本项目拟选择大兴安岭不同冻土区泥炭地为研究对象，通过野外对比观测、模拟增温、室内分析及培养实验等方法，明确大兴安岭泥炭地多年冻土退化速率和土壤不同碳库的碳累积速率，系统研究多年冻土退化对泥炭地CO2和CH4排放特征及模式、含碳气体从土壤向大气传输过程、可溶性有机碳的产生及输出过程、土壤不同碳库分解过程及相关酶活性和微生物活性的影响，揭示土壤不同碳库在多年冻土退化过程中对环境变化（融化过程、冻融作用、温度升高、氮可利用性变化及有氧和厌氧环境）的响应机制，探讨多年冻土退化对泥炭地碳排放与可溶性有机碳输出的潜在影响机理，此研究为精确评估全球变化下泥炭地碳循环过程潜在变化趋势提供理论依据和数据支持。

大兴安岭多年冻土泥炭地代表重要的碳库，但缺少气候变暖和多年冻土退化对其碳排放和输出过程的影响研究。本项目选取不同多年冻土区泥炭地为研究对象，采用对比研究，通过野外样品采集、观测与室内培养实验，系统研究了气候变暖和多年冻土退化对大兴安岭泥炭地土壤碳组分、碳库及分解、含碳气体排放及土壤可溶性有机碳（DOC）等影响，评估了泥炭地碳排放与输出的潜在变化趋势。研究发现：（1）大兴安岭泥炭地炭地土壤易分解组分和碳库含量高、易分解化学组分含量高，多年冻土泥炭地土壤碳库代表易分解碳库；（2）泥炭地土壤难分解碳库温度敏感性系数高，多年冻土融化后分解的温度敏感性系数也较高，多年冻土退化将促进土壤有机碳的分解，并且土壤酶在此过程中具有关键作用；（3）在增温1℃下，多年冻土退化速率为3.21±0.28cm（连续多年冻土区）和3.03±0.10cm（不连续多年冻土区）；（4）气候变暖将增加泥炭地CO2排放，而对土壤温度的增加是促进其CO2排放的主要原因；（5）短期增温，泥炭地CH4排放无显著增加，而融化深度是影响CH4排放的关键因子；（6）增温也显著增加了泥炭地土壤CO2浓度，但对CH4影响比较复杂；（7）增温增加泥炭地土壤DOC的含量；（8）泥炭土与多年冻土DOC释放的温度敏感性系数（Q10）为1.33-5.29，SUVA254及土壤酶在泥炭地土壤DOC释放过程中具有关键作用；（9）在不同气候变化预案下，泥炭地CO2排放将增加，并且秋季的增幅最大，长期来看，由于多年冻土退化，泥炭地CH4排放也将增加，而泥炭地土壤DOC含量增幅将高于碳排放，其变化不容忽视。4年来，项目已发表SCI学术论文2篇，已接收国内核心期刊论文1篇；由于本项目多野外观测研究，相关的科研成果正在陆续发表中。