About 68% of Japan’s entire land area is covered by mountainous forests (Figure 2), mostly in the upper part of the basin, while agricultural land and urban areas are distributed in the middle and lower parts of the basin. Climate is mainly based on the Asian monsoon system, with the northern region characterized by a subarctic climate and the southern region by a subtropical climate. The longitude of the natural conditions between north and south regions is large. Soils are strongly influenced by volcanic activity, but are formed from a variety of rock types, and peat soils are also present in the northern region. Hydrological and biogeochemical processes in the critical zone of Japan are strongly influenced by the above-mentioned topography, geology, and climate, which in turn are influenced by various human activities both spatially and temporally. There are various types of land use and land cover changing, such as land use change from forest to farmland, return to semi-natural ecosystem due to abandonment of farmland caused by depopulation and aging population, land use changes due to promotion of natural renewable energy use such as solar power, and land abandonment due to land use restriction caused by severe disasters such as huge earthquakes and tsunami. Those land use and cover changes will affect water and sediment transport and material cycling in the watershed in various ways. The goal of the ABRESO team of Japan is to elucidate the patterns and mechanisms of these changes.

Many of the study sites in Japan have been facing land abandonment including farmland (Figure 3), grassland (Figure 4), and forestland mainly due to depopulation, shrinkage of primary industry, and dependency on imported goods (e.g., food, timber, etc.).

In this study, we investigate various stakeholders’ perception regarding land use changes to explore sustainable land use management. In collaboration with the natural science team, we identify key stakeholders at each study site to understand their perception regarding the driver and impact of land use change, including impacts on various ecosystem services and disservices. We also aim to measure stakeholders’ preference of land management policies, and jointly develop multiple future scenarios up until 2050, using questionnaires, interviews and local workshops.