A Dark Future of Endangered Mountain Species, Parnassius bremeri, Under Climate Change

Climate and land-use changes are key factors in the habitat loss and population declines of climate change-sensitive endangered species. We assessed the climate change effects on the distribution of Parnassius bremeri, a critically endangered wildlife species in the Republic of Korea, in association with food availability (Sedum kamtschaticum and Sedum aizoon), land-use change, and dispersal limitation. We first predicted the current and future distributions of P. bremeri, S. kamtschaticum, and S. aizoon using the presence/absence data and current (2000) and future climate data (2050, 2100) with BioMod2, an ensemble platform for species distribution model projections. Then, the dispersal capacity of P. bremeri and land-use change were coupled with SDMs using MigClim. We used future climate and land-use changes predicted according to the SSP scenarios (SSP1-2.6, SSP2-4.5, and SSP3-7.0) and the dispersal model estimated from previous studies. The current distributional areas of P. bremeri were predicted to be about 10,956 km² without land-cover coupling and 8.861 km² with coupling, showing land-cover decreased by about 19% of the suitable habitat. The future predictions under climate change only showed the distribution reduced by 56% and 50% in 2050 and 2100 under SSP1-2.6, respectively, 55% and 48% under SSP2-4.5, and 44% and 14% under SSP3-7.0. Applying land-use change and dispersal capacity further decreased the future distribution of P. bremeri but trivially (about 0.42% on average). The strict conservation policies and measures for P. bremeri's habitats explain the trivial additional decrease, delaying its habitat loss. However, our results suggest that such efforts cannot halt the climate change-driven habitat loss trend of P. bremeri. Strong climate mitigation efforts and promoting the species' adaptive capacity are the only ways to reverse the tragic decline of climate-sensitive species.