保护性长期耕作下土壤动物对黑土活性有机碳的影响及作用机制

Soil fauna play an important role in regulation carbon cycling in farmland ecosystem. Variations of soil fauna have significant effects on transformation and distribution of soil labile organic carbon under long-term cultivation tillage. Quantifying contribution and influence for mechanism of soil fauna on labile organic carbon are of great importance for further understanding the effects of soil fauna in the soil ecosystem and their association with global climate changes. However, the research on this aspect is still poorly understood. This study will be focusing on the relationships of different of soil fauna and black soil labile organic fraction under long-term conservation tillage of Northern China, to 1) examine the variation in factors controlling on the transportation and distribution of dissolved organic carbon, soil microbial biomass carbon, particulate organic carbon and easily oxidized organic carbon under different groups of soil fauna, by using a combined study of field position control experiment and laboratory experiment; 2) analyze the influence and regulating effects between the soil, microbial diversity and flux of CO2,CH4, by using isotope tracer technique (13C); 3) clarify the influence mechanism of soil fauna on transformation and distribution of soil labile carbon fraction in many respects. This project is expected to provide academic evidences for understanding cycle process and driven mechanism of black soil organic carbon in farmland, and for comprehension biodiversity and ecological function of soil fauna.

土壤动物对农田生态系统碳循环有重要的调控作用，长期耕作影响下的土壤动物对农田土壤活性有机碳(LOC)的转化和分配有较大影响，其贡献的量化及影响机制的解析对进一步了解土壤动物在土壤生态系统中的作用及其与全球气候变化的关联有重要的意义，但目前这方面的研究较为薄弱。本项目选择保护性长期耕作的黑土农田为研究对象，明确不同土壤动物对可溶性有机碳、土壤微生物量碳、颗粒有机碳和易氧化有机碳的影响；结合13C同位素示踪法研究土壤动物对植物光合碳和凋落物分解碳的影响和调节，及其在土壤、微生物多样性和CO2、CH4排放间的作用；阐明土壤动物对LOC组分的转化与分配的作用机制。项目将有助于深入对黑土农田有机碳循环过程及其驱动机制、土壤动物多样性及其生态功能的认识。

土壤动物对农田生态系统碳循环有重要的调控作用，长期耕作影响下的土壤动物对农田土壤有机碳的转化和分配有较大影响，其贡献的量化及影响机制的解析对进一步了解土壤动物在土壤生态系统中的作用及其与全球气候变化的关联有重要的意义。本研究选择长期保护性耕作（NT）和常规耕作（CT）两种方式的黑土农田作为研究对象，明确不同耕作方式地表节肢动物群落的组成及其营养结构；研究农田典型土壤动物类群及其相互作用对土壤温室气体（CO2和N2O）排放的影响，探讨土壤动物在作物光合碳向根际土壤中迁移中的作用及机制。研究结果显示，不同土壤动物类群对土壤碳、氮的有效性的影响可减少或增加土壤CO2和N2O排放量；NT利于稳定的土壤环境和完整的食物网建立，更有利于碳和氮的固存及减少土壤CO2和N2O排放。13CO2标记示踪结果表明，蚯蚓的存在促进了玉米的生物量生长，蚯蚓的缺失可能影响土壤微生物的活性，限制根系来源碳的滞留。与CT土壤相比，蚯蚓在NT土壤中更易促进根系来源碳的积累。项目的研究成果，将有助于深入了解我国东北黑土农田耕作方式对农田土壤动物及其功能的影响，明晰农田土壤有机碳循环的过程和特征、地上和地下结构-功能之间的联系。