土壤有机碳动态对增温的响应及机制研究进展

Responses and mechanisms of soil organic carbon dynamics to warming:a review

陆地生态系统碳循环对气候变暖的响应受到土壤有机碳动态的调控。以往的研究开发了多样化的增温方法(如室内培养实验、野外增温实验和温度梯度采样等)来探究土壤有机碳动态对气候变暖的响应及其机制。然而,由于不同增温方法都存在一定的局限性,目前有关增温对土壤有机碳动态影响的研究无法形成一致结论。从过程上看,土壤有机碳动态主要包括碳输入与碳分解两个过程,并受到碳稳定性的调控,这三者的变化共同决定了土壤有机碳动态对增温的响应。先前的研究表明,碳输入和碳分解对增温存在积极响应,这与植物和土壤微生物活性的增强有关。但也有研究指出,由增温导致的土壤理化性质改变(如土壤水分含量降低)以及生物过程变化(如土壤微生物热适应),可能会影响碳输入和碳分解对增温的响应。需要注意的是,表层(0-30 cm)与深层(>30 cm)土壤有机碳动态对增温的响应机制可能存在差异,这是因为深层土壤有机碳的输入和分解过程受环境因子的限制,且稳定性与表层土壤存在较大差异。未来的研究应致力于开发新的增温方法,增加对深层土壤有机碳动态和气候敏感的生态系统的研究,引入新技术研究土壤有机质的来源、结构、保护机制等,关注植物-土壤动物-土壤微生物体系对增温的响应及其对土壤有机碳动态的调控作用,以改善碳循环模型中的不确定性,更准确地预测全球碳循环对气候变暖的反馈。

The alteration of terrestrial carbon cycling under climate warming is regulated by soil organic carbon(SOC)dynamics.Previous studies have developed multiple warming methods,mainly including laboratory incubation experiment,field in-situ manipulative experiment,and temperature gradient sampling,to investigate the responses and mechanisms of SOC dynamics to climate warming.However,due to the methodological limitations,the studies on the effect of warming on SOC dynamics cannot lead to consistent conclusions.SOC dynamics mainly include two processes:carbon input and carbon decomposition,and are also regulated by carbon persistence.The changes of carbon input,carbon decomposition,and carbon persistence together determine the response of SOC dynamics to warming.Previous studies showed that both carbon input and decomposition may positively respond to warming,which is related to the enhanced activities of plants and soil microbes.However,some studies pointed out that warming-induced alterations of soil physical and chemical properties(e.g.,the decrease of soil water content)and biological processes(e.g.,microbial community thermal adaptation)may affect the responses of carbon input and decomposition to warming.Moreover,inconsistent responses may arise when focusing on the SOC responses to warming in top(0-30 cm)or deep(>30 cm)soils due to the limitations of environmental factors on carbon input and decomposition in deep soils,as well as the different persistence of SOC in deep soils compared to top soils.Future research should focus on developing new warming methods,increasing research on deep soils and climate-sensitive ecosystems,introducing new technologies to study the source,structure,and protection of soil organic matter,paying attention to the response of plant-soil animal-soil microbe system to warming and its regulation on SOC dynamics,to improve uncertainties in carbon cycle models and more accurately predict the feedback of the global carbon cycle to climate warming.