National parks, wilderness areas, and nature reserves were created to preserve a sample of pristine ecosystems, but even the most remote protected areas face serious threats from climate change. Managers would benefit from a better understanding how ecosystems within protected areas may respond to global warming.
We evaluated how climate change may affect vegetation in 22 of the largest and most iconic protected areas across North America. We mapped the potential distributions of vegetation under mid- and late-century climate which we then compared to current vegetation distributions. Our results suggest that all protected areas may experience some vegetation shifts and that half of the protected areas may have very different vegetation by late-21st century compared to contemporary conditions. The general trend is towards vegetation associated with warmer or drier climates, such as forests transitioning away from cold montane conifer to more temperate conifer forests. Near complete losses of alpine communities are anticipated at the highest elevations and high latitudes, to be replaced with coniferous forest. At low elevation and latitudes, vegetation associated with novel climate conditions may form entirely new communities. These potential shifts are of great concern for conservation, as such changes imply a cascade of ecological responses for the flora and fauna dependent upon existing vegetation communities. Our findings highlight the challenges managers may face to sustain biodiversity in key protected areas across North America.