Abandonment of Cropland and Seminatural Grassland in a Mountainous Traditional Agricultural Landscape in Japan

The abandonment of traditional agricultural land is a global phenomenon, especially in mountainous areas. Although there are many mountainous villages where traditional agriculture, based on wild-plant mulching systems, is still practiced in Japan, the extent of land use change in these areas has not been quantitatively assessed. Economic theory predicts the systematic allocation of land to its maximum net value in response to distance from residential centres or demand. We tested this theory to determine whether: (1) grassland and cropland abandonment occurs far from residential centres and (2) new grassland becomes established near residential centres because its products (i.e., wild plants) are essential to traditional agriculture. We interviewed farmers from the traditional mountain village of Kosuge, Japan, to examine land use change at a parcel scale over the period 1940–2019. Our predictions were confirmed in that cropland and grassland were abandoned, while regrowth forests and plantations became established thereafter in the more inaccessible areas, in terms of distance from the village centre and slope aspect. Furthermore, new grassland developed near the centre of the village, leading to the ‘advance’ of grassland into the residential centre. Our results indicate that spatiotemporal patterns of land use change in traditional agricultural landscapes can be predicted and used to inform policies designed to sustainably maintain these landscapes and their ecosystem function.