集体林权制度改革对农户营林投入的影响机理及效应评价——基于非农就业和要素替代的双重视角

Unclear property rights are considered as an important reason for farmers’ insufficient inputs on forestland. Based on this point, the Chinese government issued the new round collective forest tenure reform in order to clarify property rights and allocate forestland to households. However, theoretically, it is still on debate that whether the tenure reform could stimulate households’ inputs on land cultivation. Empirically, the existing literature also suggests inconclusive results on this question. On this ground, this research program focuses on the mechanisms of how the collective forestland tenure reform affects households’ inputs on forestland. A special concern is emphasized on the potential effects of off-farm employment and factor substitution. The direct and indirect effects are separated and are incorporated into the empirical framework, respectively. This would yield more accurate evaluation of the reform’s effects compared to the practice that only considers the direct effect itself. In detail, through the channel of off-farm employment, the collective forest tenure reform would impose a negatively indirect effect on households’ labor input on forestland. This negative effect might mitigate the positive effect of the tenure reform, which is resulted from establishing more complete and secure property rights. In addition, it is important to investigate whether and to what extent the labor and capital inputs can be substituted during forest management, since their relationship determines the effect of the tenure reform on households’ capital inputs on forestland. The mediation effect model and panel data Tobit model will be introduced to examine the above hypotheses, and the Mundlak correction approach will be employed to estimate the unknown parameters. Policy implications will be discussed in order to improve households’ inputs incentives on forestland.

产权不明是导致农户营林投入不足的重要原因，由此引发了以明晰产权、分林到户为主要内容的新一轮集体林权制度改革。但是，林地确权能否促进农户营林投入的提高，不仅在理论分析方面存在争议，且二者关系的经验研究也未取得一致性结论。有鉴于此，本项目以集体林改对农户投入的影响机理为着眼点，在非农就业和要素替代的双重视角下，将林地确权对营林投入的直接和间接效应进行区分；并将二者全部纳入实证分析框架中，由此避免建立单线因果关系而掩盖实践本身的复杂性。具体而言，集体林改可能会通过非农就业渠道对营林劳动投入产生负向的间接影响，从而抵减林地确权引致的正向投入激励。而营林生产中劳动和资本是否存在要素替代关系、以及替代程度如何，则决定着集体林改对农户营林资本投入的净效应。在此基础上，利用中介效应模型和基于Mundlak修正技术的面板数据Tobit模型，对上述机理进行实证检验，以期提出促进农户营林积极性提高的政策建议。

新一轮集体林权制度改革通过分林到户、确权发证明晰了集体林地产权。但是，林地确权能否促进农户营林投入提高，在经验研究层面未取得一致性结论。更进一步地，确权后农户营林投入、种植结构、土地利用等行为决策的内在机制和不同行为间的逻辑关联不甚明晰。有鉴于此，本项目围绕“产权改革激励——要素投入调整——种植结构优化——土地利用响应”这一逻辑框架，对农户营林投入水平、投入结构、林种结构、林地流转等农户决策行为展开分析，揭示营林投入水平较低、投入结构调整缓慢、林种结构呈“趋经济林化”、林地流转积极性不高等问题的关键影响因素及其作用机制。在实证层面，利用国家林草局发展研究中心在全国9省（区）开展的林业调查数据对研究假说进行验证。研究发现：（1）在非农就业视角下，阐明了集体林权制度改革对农户营林积极性的影响及作用机理。IV-Tobit模型回归结果显示，集体林权制度改革提供了农户营林积极性提高的制度环境，但并非充分条件；非农就业的调节效应会导致产权的正向激励机制受限。该研究为提升农户营林投入积极性提供了有益的科学依据。（2）基于林业社会化服务供给视角，揭示了劳动力成本上升背景下农户营林投入结构调整缓慢的约束条件及作用机制。基于Mundlak修正的Tobit CRE模型回归结果显示，当前林业部门普遍较低的社会化服务供给水平使得要素替代的必要条件缺失，抑制了要素替代的实现。该研究为促进营林投入结构优化升级提供了决策参考。（3）从相对收益视角出发，揭示了商品林种植结构调整“趋经济林化”的成因。调节效应模型回归结果显示，劳动力成本上升会导致经济林面积占比下降；但集体林权制度改革的调节效应强化了相对收益的正向作用，使其占据主导性优势，导致经济林面积占比增加。该研究对商品林种植结构优化升级具有重要政策内涵。（4）识别了林地细碎化程度对农户营林投入的因果效应。PSM测算结果显示，集体林权制度改革使林地细碎化程度整体上得到改善，并导致农户营林投入增加了10%~37%。该研究为实现林地规模经营提供了决策支持。