Future projections of distribution dynamics and biomass of dwarf bamboos in northern Japan using a dynamic global vegetation model

Abstract Dwarf bamboo (DB) species are widespread across East Asia, including northern Japan, where they form pure communities and strongly influence ecosystem structure and vegetation dynamics, including tree regeneration. The regional distribution of different DB types is strongly associated with maximum snow depth, which is expected to decrease under future warming. Climate-induced changes in snow conditions may therefore alter both the distribution and biomass of DB vegetation. However, dwarf bamboo and its sensitivity to snow conditions have rarely been represented in vegetation models, such as dynamic global vegetation models, which limits our ability to project the effect and change of DB under climate change. In this study, we developed a dwarf bamboo submodule within the SEIB-DGVM framework to simulate future changes in the distribution and aboveground biomass (AGB) of DB species in Hokkaido, northern Japan. Under the RCP8.5 scenario, our simulations indicate that Sasa nipponica , a smaller species adapted to shallower snow conditions, is likely to expand its distribution. Across three different climate datasets under the RCP8.5 scenario, an average of 72.8% of the grid cells classified as the tall-stature type under the present-day climate were projected to shift to the short-stature type. Simulated AGB responses differed depending on whether the dominant DB type remained stable or shifted between types. Across all grid cells, mean AGB decreased by 403 g DM m⁻ 2 , corresponding to approximately 16.1% decrease relative to the current climate. Our results demonstrate that climate-driven reductions in snow depth can cause substantial shifts in the distribution and biomass of dwarf bamboo. Explicitly representing these snow-mediated vegetation shifts in DGVMs may therefore improve projections of non-tree vegetation dynamics under climate change. The developed model provides a framework for evaluating future changes in dwarf bamboo vegetation and their ecological consequences in northern Japan.