太湖流域农田生态系统服务权衡-协同机制与优化

According to the scientific issues of the interactions and impact mechanisms in studying the tradeoff and synergy among ecosystem services of the agroecosystems, and the practical demands in water environment protection and ecosystem services optimization of the agroecosystems in the Taihu Lake Basin, three major aspects of this project will be investigated as the following：(1) Quantities, characteristics and key processes for five key ecosystem services (water quality purification, greenhouse gas adjustment, grain production, nutrient supply, soil formation) of the agroecosystems and environmental factors under two different farming modes will be synchronously observed and analyzed, based on eddy covariance techniques, farmland plot runoff experiments and soil sampling analysis. (2) Temporal and spatial patterns of these 5 key ecosystem services under two different farming modes in recent 30 years will be simulated by the calibrated APSIM model with field observation data. The forms, types, impact mechanisms and scale effects for the tradeoffs and synergies among these 5 key ecosystem services will be revealed based on the simulations. (3) A tradeoff and optimization model of ecosystem services for the agroecosystems in the Taihu Lake Basin will be established by integrating APSIM model, EcoMetrix model and multi-objective optimization model. The optimizing paths and promoting policy for integrated ecosystem services of the agroecosystems in the Taihu Lake Basin will be suggested, based on the findings from the scenarios’ simulations on the temporal and spatial patterns of multiple ecosystem services of the agroecosystems, which are estimated by the above tradeoff and optimization model of ecosystem services. The successful implementation of this project will not only help to develop a "win-win" policy between agriculture sustainable development and water environment protection in the Taihu Lake Basin, but also enrich the theories and methods in studying the tradeoff and synergy among ecosystem services.

从农田生态系统服务权衡与协同的相互作用与影响机理以及太湖流域水环境保护与农田生态系统服务优化的现实需求出发，开展三方面研究：（1）针对不同耕作模式，结合涡度相关法、农田小区实验和土壤采样分析，开展5类生态系统服务（水质净化、温室气体调节、粮食生产、养分供给和土壤形成）及环境因子野外同步观测，辨识5类关键生态系统服务大小、变化特征及关键过程；（2）基于野外观测数据率定APSIM模型，模拟两种不同耕作模式下近30年5类关键生态系统服务时空格局，揭示其权衡与协同的表现形式、类型、影响机理与尺度效应；（3）集成APSIM模型、EcoMetrix模型和多目标优化模型，构建农田生态系统服务权衡与优化模型，基于多目标情景模拟与评估5类生态系统服务的协同效应，提出农田生态系统服务整体优化路径与提升对策。本课题可为太湖流域水环境保护与农业可持续发展提供“双赢”政策措施，有助于丰富生态服务权衡研究理论与方法。

从农田生态系统服务权衡与协同的相互作用与影响机理以及太湖流域水环境保护与农田生态系统服务优化的现实需求出发，开展了5类生态系统服务及环境因子野外同步观测，辨识5类关键生态系统服务大小与变化特征；利用DNDC和APSIM模型，模拟了近30年5类关键生态系统服务时空格局，揭示其权衡与协同的关系与尺度效应；集成APSIM模型多目标优化模型，提出农田生态系统服务整体优化路径。结果表明：（1）太湖流域稻田为显著的CH4源，排放通量为28.947g/m2，主要影响因子为土壤温度、土壤水分、土壤电导率和摩擦风速；（2）1985-2017年太湖流域稻田甲烷排放均值为185kg/ha，排放强度整体上呈显著下降趋势，高值主要集中分布在环太湖区域（西南部除外）、太湖流域南部以及东部区域；（3）太湖流域1986-2017年粮食单产平均13597kg/ha，总体处于上升趋势；（4）太湖流域1986-2017年氮流失总体呈增加趋势，高值主要分布在太湖东部以及东南部的昆山、吴江、海盐、平湖和金山等；（5）太湖流域1986-2017年N2O排放年均2.14kg/ha，总体呈增长趋势，高值主要集中分布在太湖中东部区域；（6）太湖流域1985-2017年土壤有机碳为累积状态，累积幅度呈现持续下降趋势，高值主要分布在昆山市、奉贤区、平湖市、海盐市、海宁市和桐乡市；（7）点位尺度上，粮食供给与固碳、水质调节与N2O排放调节两两间存在较显著的协同关系，粮食供给与水质调节、固碳与水质调节、粮食供给与N2O排放调节两两之间存在显著的权衡关系，固碳与N2O排放调节呈弱权衡关系；流域尺度上，粮食供给与固碳、水质调节与N2O排放调节存在显著的协同关系，粮食供给与水质调节、粮食供给与N2O排放调节、固碳与水质调节、固碳与N2O排放调节之间存在显著的权衡关系；（8）在水环境改善和粮食稳产前提下，减量施肥20%和稻麦秆全还田为生态系统服务整体提升的最佳路径。本课题可为太湖流域水环境保护与农业可持续发展提供“双赢”政策措施，有助于丰富生态服务权衡研究理论与方法。