Arctic-Alpine Plants Decline over Two Decades in Glacier National Park, Montana, U.S.A.

Abstract

Climate-based models predict global warming will cause mountain plants to migrate upward with local extirpation of species currently restricted to the highest elevations. Alpine monitoring studies have generally documented changes in alpine plant distributions consistent with these predictions; however, relatively few such studies have been reported from North America. I estimated canopy cover in 71 permanent microplots at two alpine moist-turf sites in Glacier National Park, Montana, U.S.A., three times between 1988 and 2011. Mean annual and summer temperatures were approximately 0.6 and 0.7 °C higher than the previous four decades, respectively. Plants more restricted to high elevations declined more than species with a broader elevational amplitude during this time. Dicots were more likely to have declined than monocots. These data support predictions and provide information that may help refine climate-envelope models.

Acknowledgments

Kathy Ahlenslager, Teri Allendorf, Jennifer Asebrook, Levi Besaw, Tara Carolin, Ann DeBolt, Pete Del Zotto, Jennifer Hintz, Laurie Kurth, Bruce McCune, and Diane Taylor assisted in the field. Rober Pal provided helpful comments on the manuscript. This study was funded by the U.S. National Park Service.