雪被对三江平原湿地土壤CO2排放的影响及其时滞效应

Snow cover is an important component of ecosystem, having unique ecological effects on soil temperature and water content, e.g. thermo-insulation effects and water-retaining effects. Generally snow cover plays an active role of biosphere in winter season in northern temperate regions, which in turn controls various ecosystem processes, especially plays a crucial role in regulating ecosystem carbon source/sink transition. The present study is carried out in the Sanjiang Plain wetland, Northeast, China, combining in-situ field experiment and in-lab manipulated experiment, to 1) determine the response of soil CO2 emission to snow cover in snow-melt period, 2) quantify the relative contributions of both soil temperature and water content to soil CO2 effluxes and the trade-off dynamics between the two variables and 3) estimate the time-lag effects of snow cover on soil CO2 emission during plant growing-season. Our objectives are to examine the impacts of snow cover, soil temperature and water content on soil CO2 emission from wetland soil in snow-melt period, assess the dynamic decay process and duration time of the influences of snow cover on soil CO2 emission from wetland soil in plant growing-season, and thus find out the process and mechanism of snow cover in regulating soil CO2 emission. Our results can give insights for scientifically evaluating the role of snow cover in soil CO2 emission and reasonably assessing the contributions of northern wetlands to global greenhouse gas budgets.

雪是生态系统的重要组成部分，对土壤具有保温、保湿等独特的生态作用，是北方温带地区冬季生物圈中最为活跃的自然因素，影响着生态系统的各种生态过程，特别是在调节生态系统碳源/汇功能中发挥着重要作用。本项目以东北三江平原湿地为研究对象，采用野外原位实验和实验室控制实验，重点研究（1）融雪期土壤CO2排放对雪被的响应；2）融雪期土壤温度、含水量在土壤CO2排放过程中的贡献及其动态权衡性；（3）植物生长季雪被对土壤CO2排放的时滞效应。以期明确在融雪期雪被和土壤温度、含水量对湿地土壤CO2排放影响的动态过程，雪被融化后影响湿地土壤CO2排放的衰减过程和时效性，揭示雪被对湿地土壤CO2排放的调节过程与作用机制。为科学阐释雪被在湿地土壤CO2排放中的作用提供科学依据，为合理评估雪被条件下北方湿地对全球温室气体的贡献提供科学资料。

雪是生态系统的重要组成部分，对土壤具有保温、保湿等独特的生态作用，是北方温带地区冬季生物圈中最为活跃的自然因素，影响着生态系统的各种生态过程，特别是在调节生态系统碳源/汇功能中发挥着重要作用。本项目以东北三江平原湿地为研究对象，采用野外原位实验和实验室控制实验，重点研究（1）融雪期土壤CO2排放对雪被的响应；2）融雪期土壤温度、含水量在土壤CO2排放过程中的贡献及其动态权衡性；（3）植物生长季雪被对土壤CO2排放的时滞效应。探讨了水热条件改变对CO2排放的影响及其时滞性效应，结合野外原位和室内控制实验重点比较分析了不同雪被处理条件下湿地生态系统CO2排放的分异规律以及土壤水热因子的调控作用，初步揭示了雪被变化对三江平原湿地CO2排放的影响以及土壤温度、含水量对土壤CO2排放影响的综合和独立作用及其动态贡献，为评估未来全球变化背景下三江平原湿地碳排放及其对区域全球变化的作用提供了科学依据。完成了项目预定目标。