Tundra conservation challenged by forest expansion in a complex mountainous treeline ecotone as revealed by spatially explicit tree aboveground biomass modeling

The subarctic forest tundra transition zone is one of the most vulnerable ecological regions worldwide and susceptible to climate change. Forest changes could lead biodiversity losses when areas become colonized. However, impact complex landscapes with barriers channels for seed dispersal highly understudied. Hence, we investigated potential tree aboveground biomass (AGB) change in mountainous central Chukotka (Siberia) individual-based spatially explicit vegetation model Larix simulator (LAVESI). In a sensitivity study, simulate dynamics until 3000 CE Representative Concentration Pathways (RCPs) without hypothetical cooling after 2300 twentieth-century levels. current state spatiotemporal AGB are validated against field satellite-derived data. Our results suggest densification existing stands lagged expansion depending on distance line (~39 percent total study area, RCP 8.5) under all considered scenarios. scenarios CE, forests stopped expanding then gradually retreated their pre-twenty-first-century position (~10 percent, 8.5). remnants remain colonized leaving an imprint former areas, which will likely have adverse biodiversity.