Arctic and alpine rare plant population dynamics at Isle Royale National Park: Response to changing lake levels
Sanders S, Kirschbaum J, Johnson SE. 2022. Arctic and alpine rare plant population dynamics at Isle Royale National Park: Response to changing lake levels. Natural Resource Report. NPS/GLKN/NRR—2022/2350. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/nrr-2291496
Arctic and alpine rare plant species populate wave-splashed rocky shorelines of Isle Royale National Park, where summer temperatures are moderated by Lake Superior. Using data from the mid-1990s and resurvey data from 1998, 2003, and 2016, we examined trajectories of change in occurrence for 25 species at 28 sites coincident with rising lake levels that followed a period of sustained low levels. We analyzed changes in site occupancy of species individually and by functional, geographic, and microhabitat groupings. We also assessed change in population structure for four focal species: Saxifraga paniculata, S. tricuspidata, Pinguicula vulgaris, and Vaccinium uliginosum. Of the 25 species, site occupancy increased for 13 and remained steady for six, declining in another six. Site occupancy did not change over time within functional, geographic, and microhabitat groupings. The four focal species showed similar dynamic and systematically changing populations, responding to similar ecological exposures. We hypothesize that the moderating influence of Lake Superior on air temperature benefits these populations despite warming temperatures and a 15-year sustained low water period. This work contributes to our understanding of the responses of at-risk species to extreme climate events.
- Type
- Published Report
- Authors
- Sanders, Suzanne; Kirschbaum, Jessica; Johnson, Sarah
- Date of Issue
- 2022-02
- Publisher
- National Park Service
- DOI
- 10.36967/nrr-2291496
- Units
- GLKN , ISRO , NRSS
- Keywords
- GKLN, Isle Royale, Lake Superior, Michigan, rock pools, splash pools, Vegetation Monitor