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

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.

The need for stewardship of lands exposed by deglaciation from climate change

“…Similarly, in the Anthropocene, microclimatic changes will produce cold-air pooling and temperature inversions (Gentili et al, 2015) and possible colder microrefugia within the larger warming landscape. Therefore, some present-day environmental conditions might be maintained, at least in the near-term, as other habitats change (Brighenti et al, 2021), allowing for some cold adapted species threatened by summit traps ("nowhere to go" hypothesis; Loarie et al, 2009) to survive (Gobbi et al, 2021). The poor knowledge we have of this almost vanished cold habitat and climate dynamism, however, makes more research a necessity.…”

Vegetation Ecology of Debris-Covered Glaciers (DCGs)—Site Conditions, Vegetation Patterns and Implications for DCGs Serving as Quaternary Cold- and Warm-Stage Plant Refugia

“…Increasing attention is also paid to DCGs from an ecological perspective, including a focus on flora [44][45][46][47][48][49][50], fauna [48,[51][52][53][54][55], microbes [56] and interactions between different organism groups [57] (Figure 2). The increasing ecological interest on DCGs is also related to the fact that these landforms were recognized as potential refugia for plants (and other organisms) during warm and cold stages in the past [44,45,47,53,54,58]. This has implications in space and time for post-glacial recolonization patterns [45], for primary succession in glacier forelands [59,60] and for the survival of cryophilous taxa under cur-rent climate warming due to the thermal inertia of DCGs [47,53,54].…”

“…Diversity 2022, 14, x FOR PEER REVIEW 4 of 26 organisms) during warm and cold stages in the past [44,45,47,53,54,58]. This has implications in space and time for post-glacial recolonization patterns [45], for primary succession in glacier forelands [59,60] and for the survival of cryophilous taxa under current climate warming due to the thermal inertia of DCGs [47,53,54].…”

Active rock glaciers of the contiguous United States: geographic information system inventory and spatial distribution patterns

“…Additionally, and especially when compared to glaciers, rock glacier meltwaters exhibit unique hydrographs (Bajewsky and Gardner, 1989;Jones et al, 2019b) and hydrochemistry signatures (Millar et al, 2013a;Fegel et al, 2016), as well as also volumetric discharge increases in late summer due to climate change (Caine, 2010). From an anthropogenic perspective, active rock glaciers represent unique engineering challenges, particularly with regard to the possibility of catastrophic collapse and debris flow generation (Iribarren and Bodin, 2010;Lugon and Stoffel, 2010;Bodin et al, 2017), but they also offer engineering opportunities as reservoirs of construction aggregate and water (Burger et al, 1999).…”