气候变化对农田生态系统碳氮过程的影响及其对生产的启示

Adaptation of Cropland Ecosystem Carbon and Nitrogen Process to Climate Change and Indication for Agricultural Managements

从农田生态系统过程角度综合分析了气候变化（[CO2]增加、温度升高）对土壤碳库、氮供给生物化学过程的综合影响和长期效应。总结指出，[CO2]增加、温度升高对农田生态系统过程的影响具有明显的时间效应，短时间尺度上加快农田土壤养分周转，改变碳氮组分，长时间尺度上导致土壤养分有效性降低；[CO2]增加、温度升高和养分管理对农田生态系统过程的影响具有显著的交互作用，土壤养分有效性制约着气候变化对农田生态系统生产力和碳汇功能的影响。因此，气候变化（[CO2]增加、温度升高）情景下对农业生产管理包括施肥运筹及秸秆还田策略等的启示在于：根据气候变化背景下土壤养分的周转规律有效管理农田土壤养分、保持农田土壤肥力，从而保障农业高产的可持续性以及农田碳汇的生态服务功能。

Impacts of climate change on cropland ecosystem carbon and nitrogen process have been comprehensively assessed and reviewed. However, climate change effects with regard to elevated CO2 and increased temperature and their interactions on long-term scale basis are poorly understood. Results of this research showed clear time scale effects of climate change. On a short time horizon, elevated CO2 and increased temperature speeded up the turn over of nutrients, changed the composition and ratio of soil carbon and nitrogen. However, on long term scale, elevated CO2 and increased temperature decreased the nutrients availability, leading to progressive nitrogen limitation. Results also showed substantial interactive effect of elevated CO2 and increased temperature and nutrient managements on ecosystem carbon and nitrogen cyclings. Significant interactions existed between elevated CO2 and increased temperature on soil carbon sequestration, leading to insignificant change of soil carbon sequestration. Moreover, the effects of nutrients management on crop ecosystem were depended on elevated CO2 and increased temperature and their interaction. The availability of soil nutrients limited the productivities of agricultural ecosystem, and consequently soil carbon sequestration. Principally, relatively higher rate of fertilizer, particularly N fertilizer, than usual recommended dose under the current scenario was required for sustainable high crop yield. Additional N could be compensated with straw return under climate change scenario for the purpose of ecosystem functioning of soil carbon sequestration. Therefore, fertilizer management and straw amendment practices should be improved based on the soil nutrients dynamics under elevated CO2 and increased temperature.