Ecotone might provide key refugium for sky island mammals in the southern Appalachian Mountains
Sky islands are highly biodiverse yet climate‑vulnerable ecosystems. Surveys on Grandfather Mountain and Roan Mountain Highlands reveal that the spruce‑fir–northern hardwood ecotone may act as a refugium for mammals associated with Southern Appalachian spruce‑fir forests. Four of five target small‑mammal species occurred in both spruce‑fir and ecotone habitats, with species richness, alpha diversity and bat activity often highest in the ecotone. Abundance patterns varied by species, but results consistently highlight the ecotone’s conservation value. Protecting this transitional zone alongside spruce‑fir forests is essential for safeguarding climate‑sensitive sky‑island mammals.
Subject Tags
- Forest
- Climate impacts
- Wildlife
Abstract
Sky islands, ecosystems found on geographically isolated mountain peaks, are among the most biodiverse ecosystems in the world but face a disproportionately high threat from climate change. High-elevation, montane ecosystems, which are already at their upper altitudinal limits, are predicted to severely contract in response to climate change. The identification and conservation of refugia is an increasingly important approach for protecting biodiversity associated with imperiled ecosystems. We explored the spruce-fir–northern hardwood ecotone as a possible refugium for mammals in the Southern Appalachian red spruce (Picea rubens)-Fraser fir (Abies fraseri) sky islands. We conducted livetrapping, camera trapping, and ultrasonic acoustic surveys to characterize mammal diversity across the spruce-fir–northern hardwood forest gradient on Grandfather Mountain and Roan Mountain Highlands in western North Carolina, USA. We detected four out of the five spruce-fir-associated small mammal species in both spruce-fir and ecotone habitats. Mammal species richness, alpha diversity, and bat activity tended to be higher in the ecotone than in the other forest types on both mountains. Next, the abundance of small mammals associated with spruce-fir was higher in the spruce-fir and ecotone forests for one of the three species we were able to estimate. Together, our results suggest that the spruce-fir–northern hardwood ecotone might serve as refugium for mammal species that are associated with spruce-fir sky islands in the Southern Appalachian Mountains and mammalian conservation efforts in this biodiversity hotspot should consider focusing on the ecotone in addition to the adjacent spruce-fir ecosystem.
Citation
Mallinoff, J. A., Petric, R., Diggins, C. A., Kierepka, E. M., Arbogast, B. S., Jenkins, A., & Zimova, M. (2025). Ecotone Might Provide Key Refugium for Sky Island Mammals in the Southern Appalachian Mountains. Ecology and Evolution, 15(10), e72374. https://doi.org/10.1002/ece3.72374
TNC Authors
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Jenifer A. Mallinoff
Southern Blue Ridge As-Needed Burn Crew Leader, North Carolina
The Nature Conservancy
Email: jenifer.mallinoff@tnc.org