The Possibility of Using Abandoned Farmlands for Habitat Restoration in Societies with Decreasing Populations

Abstract

The human population in several developed countries, including Japan, has been gradually decreasing after the end of an era of population growth in which development was actively pursued. Assuming that human-modified lands are abandoned with decreasing population, we may ask whether such abandoned lands might be used for the restoration of ecosystems that have decreased due to the development during the era of population growth. In this chapter, we summarize the occurrence factors and status of abandoned farmlands in Hokkaido, in order to assess whether such farmlands can be used to restore forest ecosystems for the habitat of Blakiston's fish owl or wetland ecosystems for the habitat of the red-crowned crane. With the advent of the era of population decline, social drivers, such as population, were found to start affecting the occurrence of farmland abandonment. Although currently social drivers have less influence than geological drivers that determine the difficulty of cultivation, social drivers are likely to increase in importance in the future; therefore, we need continuous and careful observation of them. We focused on farmlands that used to be forest or wetland before reclamation, and had the potential to be restored as forest or wetland ecosystems, and assessed the occurrence of abandoned farmlands. The results showed that the distribution of the former varied across regions, and the occurrence factors of the latter also varied. Whether or not the abandoned farmland in a given area can be a useful option for nature restoration in the area depends on the type of ecosystem that is targeted for restoration and on the distribution of abandoned farmlands with a history that included this ecosystem. Therefore, we must develop a restoration plan for each area, including reorganization and maintenance of the land use of abandoned farmlands and their surroundings.