放松退耕地间种约束的政策合理性与有效性检验——基于贵州省新一轮退耕还林的农户调查

新一轮退耕还林在保护生态环境和促进农户增收方面被赋予重要期待。本文基于范围经济理论,利用贵州省的退耕农户调查数据,测算农户的间种的范围经济和范围利润水平,利用似不相关回归和面板Tobit模型分析间种对农户范围经济、范围利润和经济林管护的影响。研究发现,放松退耕地间种约束具有一定的合理性,但其有效性的发挥还需进行相应的政策调整。具体表现为：①双作物间种的范围经济水平高于单作物间种,经济作物间种的范围利润水平最高。具体的,“经济林+豆类+薯类”的范围经济值最高,平均值为0.835;“经济林+豆类”和“经济林+烤烟”的范围经济水平最低,平均值分别为0.205和0.142;“经济林+豆类”的范围利润值最低,平均为-0.457,“经济林+烤烟”的范围利润值最高,平均为0.908。②间种强度与范围经济、范围利润之间存在“倒U型”关系,间种并非越多越好;间种强度每增加1%,经济林的成活率会增加3.0%,但随着间种强度的增加,经济林的成活率将逐步下降;③相比间种粮食作物,种植经济作物更不利于经济林的管护。本文研究结果可为巩固新一轮退耕还林成果提供现实依据和理论参考。

Policy feasibility and effectiveness test of relaxing constraints of interplanting in returning farmland: Based on a survey of farmers in Guizhou Province

To explore the feasibility and effectiveness of the policy of relaxing constraints of interplanting in the new round of returning farmland to forests (NRRFF) in Guizhou province, and to provide a reference for consolidating the results of the NRRFF and improving the NRRFF policy, the economies of scope and profit of scope of interplanting of farming households were measured using the economies of scope model. The effects of interplanting on farmers’ economies of scope, profit of scope, and economic forest management and protection were analyzed by using quasi-irrelevant regression and panel Tobit model. The research found that: Interplanting can bring economies of scope and profit of scope to returning farmland households, of which “economic forest + food crops” has the highest degree of economies of scope, and “economic forest + cash crops” has the highest degree of profit of scope. From the perspective of the interplanting models, the degree of economies of scope brought by single-crop intercropping is slightly lower than dual-crop intercropping, but interplanting of economic crops can bring greater degree of profit of scope. There is an inverted U-shaped relationship between the intensity of interplanting, economies of scope, and profit of scope, and there exists a threshold value for interplanting intensity considering the economies of scope and profit of scope. Cross-effects indicate that interplanting intensity will affect the degrees of economies of scope and profit of scope of farmers through the survival rate of interplanted trees of economic forests. Compared to food crops, interplanting economic crops is not as beneficial to the management of economic forests.