增温下退化沼泽土壤动物格局与其碳循环调控功能响应及机制

Global warming has already been proved and now widely accepted. Increasing temperature not only affects the vegetation composition, but also the soil fauna structure their function. More and more studies indicated soil fauna facilitates the soil carbon dynamics via their feeding activities and trophic interactions with soil microbes. Nonetheless, the warming-induced changes in soil fauna structure and their function on soil carbon cycling have not been well investigated to date in comparison with much research attentions on plants. However, this is critically important for explaining the coupling relationship among global change, biological pattern, ecological process and function. To date, little is indeed known about the reponses of soil fauna structure and their functions of soil carbon cycling to climate warming for marsh wetlands. This program will select the marsh wetlands in the Sanjiang Plain, Northeast China, as the filed research sites. Methods at different scales will be used to test and prove our hypotheses, including field investigation, soil cores transplant experiment, OTC warming, in situ control, stable isotope analysis (13C and 15N) and laboratory simulation. We will investigate the dynamics of soil fauna community composition and distribution pattern under increasing temperature. Then we elucidate the soil fauna impacts on soil organic carbon cycling, including decoposition, mineralization, greenhouse gas emission and DOC variation. In addition, the coupling relationship will also be revealed between soil fauna structures and their functions on soil carbon cycling with flooding regimes, soils and plants characteristics. Basing on the above studies, we will construct an successive mechanism model including the typical pattern and core ecological processes. A better understanding of effects of climate changes on the community strucutre and function of soil fauna basing the program can aid predictions of how soil ecosystems may function under future climatic conditions.

全球变暖已成为不争的事实。气温升高，不仅影响地上植被，还直接或间接影响地下生态系统结构和功能。增温背景下土壤动物对土壤有机碳（SOC）调控功能变化受到特别关注，但相对地上植被，其研究刚刚起步。而这是阐明沼泽“气候变化-生物格局-生态过程-功能效应”耦合关系对全球变暖响应的关键。增温下退化沼泽土壤动物格局如何变化，这种变化是否会改变其碳循环调控功能还不清楚。选择三江平原沼泽作为研究对象，运用原状土柱水平移位、OTC增温控制、同位素示综（13C和15N）和室内模拟等方法，阐明退化沼泽土壤动物格局对增温的响应特征，揭示增温下土壤动物对沼泽SOC分解、矿化、含碳温室气体排放和可溶性有机碳（DOC）动态等SOC循环过程的作用及贡献变化，明确退化沼泽土壤动物格局及其土壤碳调控作用对增温的响应机制，构建融合关键格局和过程的响应机制模型。项目将有助于加深全球变化下土壤生物多样性与沼泽系统功能关系的理解。

项目以全球变暖为背景，研究气温升高直接或间接对地下生态系统结构和功能的影响，揭示了增温背景下土壤动物对土壤有机碳（SOC）调控功能变化，深化了对沼泽“气候变化-生物格局-生态过程-功能效应”耦合关系对全球变暖响应的理解。项目选择三江平原沼泽作为研究对象，运用原状土柱水平移位、OTC增温控制、同位素示综（13C和15N）和室内模拟等方法，研究发现增温改变了沼泽湿地土壤微节肢动物的群落组成；对自然沼泽湿地跳虫的密度具有正效应，而对低水位湿地中的土壤跳虫密度具有负效应；增温降低了沼泽湿地土壤动物的营养级，且甲螨营养级对增温的响应比跳虫敏感；从而阐明了退化沼泽蚯蚓、螨类和跳虫等土壤动物格局对增温的响应特征。通过室内模拟发现，增温促进了湿地土壤温室气体（包括CO2、CH4、N2O）累积排放量的增加，揭示了增温下大型土壤动物（蚯蚓）对沼泽SOC分解、矿化、含碳温室气体排放和可溶性有机碳（DOC）动态等SOC循环过程的作用及贡献变化。研究发现增温下土壤动物类群和分布的变化，通过调控碳矿化和稳定性改变碳循环过程和功能。从土壤动物调控土壤微生物组成和多样性（如甲烷菌、甲烷氧化菌）和土壤理化性质等角度，明确了退化沼泽土壤动物格局及其土壤碳调控作用对增温的响应机制。项目有助于加深全球变化下土壤生物多样性与沼泽系统功能关系的理解。