Conversion patterns of agricultural lands in plains and mountains: An analysis of underpinning factors by temporal comparison with geographically weighted regression in depopulating rural Japan

The substantial decline and aging of Japan's rural population have severely affected the maintenance of agriculture in these areas, resulting in the abandonment of agricultural land and its subsequent conversion to other land use types. This study quantified land use changes in Matsusaka City, Mie Prefecture, Japan, in order to analyze the factors that influence the substantial change in agricultural land area, which represents a generated trend. Most cities and villages experienced a decrease in agricultural land area, with the rate of change and potential contributing factors differing based on their geographical location. While most agricultural land in the plains was converted to residential land, agricultural land in mountainous areas was transformed into forest or wasteland areas at a significantly higher rate. Our results suggest that the management and maintenance of agricultural land in plains are more likely than in mountainous areas. The agricultural land in mountainous areas remained stable and unaltered at higher elevations, whereas it was diverted at lower elevations. Subsidies, such as the Direct Payment System for Hilly and Mountainous Areas, likely influenced this outcome. This suggests that agricultural land in mountainous areas eligible for subsidies under the direct payment system, such as highly mountainous areas, can be readily maintained. In contrast, agricultural land situated in mountainous boundary areas that lack subsidies is more amenable to conversion. This regional study elucidates land use change factors, particularly agricultural land change factors, and contributes to measures for other parts of Japan and other countries with depopulation and aging problems.