Moso-bamboo forests in Japan: What are the effects of their area expansion on ecosystem services?

Recently, mosobamboo (Phyllostachys pubescens) forests have been expanding in Japan. Some studies have pointed out their expansion could decrease ecosystem services. This paper summarized expansion rates in areas in the last ca. 70 years and biomass of moso-bamboo forests. We verified whether the expansions could increase risks in flood, water shortage, shallow landslide, and soil erosion. Many papers have reported increases in areas of moso-bamboo forests, and the average expansion rate was 1.03 ha/ha year. The rate in the surrounding open spaces tends to be larger than that in the surrounding closed spaces. Aboveground biomass in moso-bamboo forests was between 62.6 and 224.3 t/ha. The maximum aboveground biomass in moso-bamboo forests would be smaller than those in Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa) forests. However, only a few studies examined belowground biomass in moso-bamboo forests. As well, based on results in previous studies, we concluded that risks in flood, water shortage, shallow landslide, and soil erosion in moso-bamboo forests would not be higher than those in other types of forests. This conclusion is different from the speculation. On the other hand, this conclusion was based on only a few studies. Therefore, further studies are required to clarify various processes related to flood, water shortage, shallow landslide, and soil erosion in moso-bamboo forests with various canopy structures under various meteorological conditions.