Rock glaciers and related cold rocky landforms: Overlooked climate refugia for mountain biodiversity.

Stefano Brighenti,Masaki Hayashi,Lusha M Tronstad,Scott Hotaling,Jasmine E Saros,Constance I Millar,David Herbst,Andrew G Fountain,Debra S Finn

doi:10.1111/gcb.15510

Abstract

Mountains are global biodiversity hotspots where cold environments and their associated ecological communities are threatened by climate warming. Considerable research attention has been devoted to understanding the ecological effects of alpine glacier and snowfield recession. However, much less attention has been given to identifying climate refugia in mountain ecosystems where present-day environmental conditions will be maintained, at least in the near-term, as other habitats change. Around the world, montane communities of microbes, animals, and plants live on, adjacent to, and downstream of rock glaciers and related cold rocky landforms (CRL). These geomorphological features have been overlooked in the ecological literature despite being extremely common in mountain ranges worldwide with a propensity to support cold and stable habitats for aquatic and terrestrial biodiversity. CRLs are less responsive to atmospheric warming than alpine glaciers and snowfields due to the insulating nature and thermal inertia of their debris cover paired with their internal ventilation patterns. Thus, CRLs are likely to remain on the landscape after adjacent glaciers and snowfields have melted, thereby providing longer-term cold habitat for biodiversity living on and downstream of them. Here, we show that CRLs will likely act as key climate refugia for terrestrial and aquatic biodiversity in mountain ecosystems, offer guidelines for incorporating CRLs into conservation practices, and identify areas for future research.

Highlights

In high mountain areas, climate warming is proceeding 2-3 times faster than the global average, imperiling habitats associated with glaciers, permafrost, and seasonal snowpacks (Hock et al., 2019)
If habitat persistence and cold water are key to occupancy, icy seeps will act as climate refugia
More research is required, our tentative conclusion is that the cold, stable aquatic habitat of icy seeps will provide climate refugia for a substantial portion of alpine stream biodiversity

Summary

Introduction

Climate warming is proceeding 2-3 times faster than the global average, imperiling habitats associated with glaciers, permafrost, and seasonal snowpacks (Hock et al., 2019). We present a global perspective of CRL ecology in mountain ecosystems, with an emphasis on their value as refugia for cold-adapted terrestrial and aquatic biodiversity under climate change. The near-surface interiors of CRLs, provide cold micro-climates that allow pikas to persist in places where ambient conditions are often untenable, including lower elevation sites atypical of the species (Millar et al, 2018).

Results

Conclusion