A Dark Future of Endangered Mountain Species, <i>Parnassius bremeri</i>, 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 <i>Parnassius bremeri</i>, a critically endangered wildlife species in the Republic of Korea, in association with food availability (<i>Sedum kamtschaticum</i> and <i>Sedum aizoon</i>), land-use change, and dispersal limitation. We first predicted the current and future distributions of <i>P. bremeri</i>, <i>S. kamtschaticum</i>, and <i>S. aizoon</i> 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 <i>P</i>. <i>bremeri</i> 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 <i>P</i>. <i>bremeri</i> 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 <i>P</i>. <i>bremeri</i> but trivially (about 0.42% on average). The strict conservation policies and measures for <i>P</i>. <i>bremeri</i>'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 <i>P</i>. <i>bremeri</i>. Strong climate mitigation efforts and promoting the species' adaptive capacity are the only ways to reverse the tragic decline of climate-sensitive species.