Predicted scarcity of suitable habitat for alpine plant communities in northern Japan under climate change

Abstract

Question: Alpine vegetation is sensitive to climate change, with shifts in species ranges, changes in community composition, and an upward shift in the forest limit over decades. Under climate change, habitats suitable for alpine vegetation will progressively decrease in scale, making their protection and conservation particularly important. In the Taisetsu Mountains of Japan, alpine vegetation has changed remarkably during the last decade. The aim of this study was to estimate the distribution of habitats suitable for alpine and subalpine vegetation types (snowbeds, shrubs, and alpine heathland/fellfield) and competing vegetation types (Sasa spp. and subarctic forest), while considering uncertainties in future predictions and climate scenarios. Location: Taisetsu Mountains, Daisetsuzan National Park, Hokkaido (northern Japan). Methods: We estimated the habitat area suitable for each vegetation type from current vegetation maps on the basis of the predictions by three global climate models (GCMs) under two climate change scenarios (RCP2.6 and RCP8.5) using five habitat suitability models (HSMs) in two periods (2046–2050 and 2096–2100). We also compared the performances of the HSMs. Results: Mean summer temperature and snow-cover period had significant effects on the distribution of all vegetation types. The estimated distribution area for suitable habitat did not differ markedly among GCMs and HSMs. Under the RCP2.6 scenario, habitats suitable for snowbeds and alpine heathland/fellfield drastically decreased overall but were preserved in some regions. Under the RCP8.5 scenario, however, subarctic forest almost completely replaced alpine and subalpine vegetation types over time. Conclusions: Our projections indicate that the severity of future climate change will determine whether or not habitats suitable for alpine vegetation will remain. Monitoring the dynamics of endemic and rare species for the effects of global warming should be the priority for adaptation strategies to enable timely conservation measures.