基于双内生视角的非农就业对林地流转的影响研究——以福建、江西、云南集体林区为例

Since the implementation of China's new round tenure reform on collective forests, forestland rentals have been given more and more attentions, given the dilemma of “efficiency versus equity” in collective forestlands, South China. However, there is no significant increase in the speed and scale of forestland rentals in recent years. Considering the limited effects of land property rights and farmer’s emotions, more and more researches have emphasized the crucial role of off farm employment on farmland rentals, under the assumption that the decision of labor mobility is exogenous. However, the above agrument maybe not true in forestlands rentals, given the difference between forestry and agriculture. Moreover, the interaction between farmland rentals and off farm employment has been proved. That means the causality between farmland rentals and off farm employment should be examined based on the endogenous perspective, which has been ignored by the exsiting research. To fill the gap, the dual endogenous decision model will be established, in order to capture the endogenous character of forestland rentals decisions and off farm employment decisions. Under the principle of utility maximization, the Kuhn-Tucker condition will be used to obtain the optimal decisions of forestland rentals and off farm employment. The econometric models will be developed based on the above theoretical models. After obtaining the household survey data from Fujian Province, Jiangxi Province, and Yunnan Province, Seemingly Unrelated Regression will be adopted to examine the crucial influenced factors of forestland rentals, in order to promote the development of forestland rentals market.

新一轮集体林权制度改革后，南方集体林区面临着平等与效率的复杂两难，这使得林地流转成为重要选择。已有研究发现，产权完整性和农民土地情节对农地流转的作用有限。相反，在外生性假设下，非农就业对农地流转的关键作用逐渐被学界接受。然而，林业与农业的差异性，使得这一结论在林地流转中是否依然成立，尚待检验。同时，土地流转行为和非农就业行为的交互影响已被证实。这表明，不管研究哪一个方向上的因果关系，都会面临着内生性问题。这种“双内生性”，正是已有研究忽略的重要问题。基于这一逻辑，本项目拟构建符合林业特点的林地流转——非农就业“双内生”农户决策模型，在农户效用最大化原则下，利用Kuhn-Tucker条件求解最优的林地流转决策和非农就业决策，并据此构建计量模型，在福建、江西、云南三省林农调研数据的基础上，利用似乎不相关回归（SUR）技术，科学甄别出林地流转的关键影响因素，以期促进林地流转市场的健康发展。

新一轮集体林权制度改革缓解了集体林地经营的制度约束，强化了产权的完整性。集体林改后，南方集体林区面临着平等与效率的复杂两难，这使得林地流转成为重要选择。然而在现实中，集体林改后林地流转的比例依然非常低。影响林地流转的决定因素成为亟待回答的科学问题。在内生性视角下，本课题探讨了农户林地流转的决定因素，尤其关注了非农就业行为对林地流转的重要影响。本课题构建了一个基于劳动力配置和林地流转的农户决策模型，在内生性视角下阐述了非农就业对林地流转的影响机制，据此提出了研究假说。并利用国家林业局经济发展研究中心在全国9个省（区）开展的大样本多年份连续监测数据，对上述假说进行实证检验。该数据集由1497个有效样本构成，涉及全国主要的集体林区，涵盖了集体林改之前（2003年）和之后（2007到2013年）的观测值。在回归分析时，考虑到非农就业的内生性以及林地流转数据的截取性，课题分别采用了Nelson-Olson 多变量Tobit模型、Smith-Blundell 工具变量Tobit方法处理非农就业内生性问题。结果显示，非农就业行为对林地流入决策产生了显著的负向影响；相反，非农就业对林地流出具有正向的促进作用，但这种正向影响并未通过显著性检验。一个合理的解释是，土地的社会保障功能及禀赋效应对林地流出产生了重要的抑制作用。此外，林地流入决策显著地受到交易成本、木材价格等市场因素的影响，而这些因素对林地流出均不显著。这反映出林地流入是受到市场机制影响的经济决策行为，而林地流出则是更偏向于受心理因素所决定的非市场化行为。二者在行为机制上的差异性为集体林改的后续配套改革提供了政策参考。