生物多様性保全型農業への転換がもたらす経済コベネフィットの評価

——兵庫県豊岡市におけるコウノトリ育む農法を事例として——

抄録

In recent years, the conservation of biodiversity has become an increasingly important issue in agricultural policies and has led to the implementation of agricultural practices to conserve biodiversity (bio-friendly farming) . In Toyooka City, Hyogo Prefecture, practices to conserve white storks started in 1965, and through these practices farmers are trying to put added value on stork-friendly products. The local government is strongly promoting farmers' actions with a local environmental and economic policy.
Such efforts will affect not only biodiversity in the region, but also various other aspects such as the regional economy. The local government seeks to achieve co-benefits for the economy and stork conservation. They are trying to achieve positive economic impacts on the regional economy by promoting stork-friendly practices. However, bio-friendly agricultural production has both negative and positive impacts on the regional economy. Therefore, it is important for biodiversity conservation policies to understand which impact is larger.
This study evaluated the impacts on the regional economy, both negative and positive, caused by shifting from conventional to bio-friendly rice farming using a case study of bio-friendly rice farming (to help conserve white storks) in Toyooka City. After applying an input-output (IO) analysis, I considered whether bio-friendly rice farming creates economic co-benefits for the local economy.
In this study, I applied the 36-sector input-output tables for Toyooka City of the year 2005. To achieve our study purpose, I modified the IO tables by disaggregating the agriculture sector into 3 sectors (stork friendly rice, conventional rice and miscellaneous agriculture) . I evaluated the economic impacts by shifting rice production from conventional to stork-friendly production. Specifically, I calculated the impacts when the area of the stork-friendly rice farming increased from the 2005 level （41.7 hectare） to the 2008 level （141.4 hectare）.
The results showed that changing from conventional to bio-friendly rice farming had a highly induced effect （multiplier=1.57） and the positive effect was larger than the negative effect.　This implies that shifting to bio-friendly rice farming creates an increase in farm income.　However, most of the effects reside in the agricultural sector and effects on other sectors are very small.　Although the local government thinks that the economic impacts should be widespread in the regional economy to achieve synergy, the results reveal that the co-benefits are not widespread throughout the local economy.
These results show that the local policy to shift rice production to stork-friendly production brings benefits to rice farmers.　However, the policy target to bring synergy within the regional economy is not yet achieved.　These results suggest that further incentives to promote co-benefits are required, for example promotion of more domestic inputs to produce stork-friendly rice and the use of stork-friendly rice products as an intermediate input for other sectors.

JEL Classification: O13, Q51, Q57, R15, R32