农户异质性、碳汇生产激励与后退耕时代生态补偿机制研究——以黄土高原退耕区为例

Famers heterogeneity increased prominently since entering the industrial age, the main features are: First, differences in household income and its components; Second, land use changes and business models are different as well. The former decides the reflection of households to the policy sensitivity, and the latter one determines the behavior of farmers in agricultural production resulting ecological effects. Ignoring the heterogeneity the ecological compensation mechanism will inevitably lead to incentives incompatibility. From the perspective of farmers heterogeneity, "one size fits all" type of returning farmland to forest policy not only exists weak incentives in forests behavioral, but also appeared partial failure in the link of farmland abandoned; Therefore, the ecological compensation mechanism in operation works hard to play the role of encouraging carbon sinks production and ecological construction, with only the existing policy mechanisms farmland oriented production shift to carbon sequestration policy objectives plus the market mechanism can really motivate farmers to choose the production of carbon sinks.Therefore, starting from farmers heterogeneity, the project analyzes the obstacles on the internal mechanism inherent in the Grain Policy, takes the in-depth study of the mechanism of production of carbon sinks behavior of farmers, makes empirical research of the farmland in the Loess Plateau area as an example of the implementation of carbon trading paths and feasible options, and then proposes the ecological compensation mechanism incentives to enhance farmers to produce carbon sinks and innovative policy proposals as well. The study has important theoretical and practical significance for the promotion of agricultural ecological compensation system innovation especially in the new era of farmland.

进入工业时代以来农户异质性日益凸显，主要表现在：其一，农户收入及其构成差异；其二，土地利用方式、经营模式、对土地的依赖程度以及土地投资水平不同。前者决定农户对政策的反映灵敏度和参与积极性，后者决定农业生产行为产生的生态效应。在农户异质性视角下，“一刀切”式的退耕还林政策不仅存在“还林”弱激励，且在退耕环节就出现局部失灵；因此，退耕还林工程中的生态补偿机制很难发挥激励农户碳汇生产的作用，只有将现行以退耕为导向的政策机制转向以碳汇生产为目标的政策加市场机制才能真正激励农户选择碳汇生产。基于农户异质性视角，本项目以黄土高原退耕区为例，在剖析退耕工程实施内在机制障碍的基础上，深入研究碳交易情景下农户碳汇生产行为机理及激励关系，并比较政策机制与市场机制的溢出效应为退耕政策完善及市场化生态补偿制度构建提供理论基础和事实依据。本研究对于推动后退耕时代我国农业生态补偿制度创新具有重要的理论价值和实践意义。

退耕还林工程实施以来，生态环境明显改观，退耕区碳汇量显著增加；然而，经过详查与深思，发现这种改善主要得益于“扩展边际”（林地面积扩大）而非“集约边际”（林地质量提升）以及大自然的自我修复能力。与此同时，随着工程的推进以及社会经济环境的变迁，农户异质性日益凸显，尤其是兼业化程度显著提高，而兼业化通过增加化肥、农药等物化投入使农业生产日渐成为重要的碳源。这意味着退耕政策未能有效激励农户进行生态建设，同时，已获得的生态红利正日益消减。本项目以农户异质性为切入点，重审退耕政策对农户的激励有效性，揭示退耕政策的内在机制障碍，进而提出以林业碳汇生产为主的市场化生态补偿机制，最终旨在为退耕区生态补偿制度的创新与完善提供理论依据与决策参考。. 通过研究发现：（1）以兼业化衡量的农户异质性在退耕区日益凸显，农业生产的综合碳效应表现为碳排放过程；同时，运用调研数据验证了农户兼业化水平与碳排放之间的正相关关系。（2）通过数理模型证明了人力资本与兼业水平决定农户的退耕意愿及其差异化反映；考虑转换成本之后，兼业化程度较高和较低的农户分别选择经济林和生态林，选择生态林实为低效率农户的次优选择。而且，经验数据对理论分析大体上也给予了支持。（3）构建林业碳汇生产的一般均衡模型，并进一步对林业碳汇生产与退耕政策的经济社会效应进行比较分析，得出前者在农村劳动力转移、减贫效应以及激发农户“亲环境”行为等方面更具优势，从而可最大化农户的总福利。（4）以异质性为视角，构建了短期内同时包含区域与农户尺度的差异化退耕补贴政策体系；长期内，以四维系统与双代理理论为基础，对融入林业碳汇生产的生态补偿长效机制进行理论探索。. 在结合定性与定量分析的基础上，本项目对退耕政策与退耕区生态补偿机制的研究更加侧重与突出理论分析，在对相关问题缺乏统一分析框架与理论基础的研究背景下本课题努力在该方面做出了一些有意义的尝试与探索。