Dynamics of Ecological Communities Following Current Retreat of Glaciers

Abstract

Glaciers are retreating globally, and the resulting ice-free areas provide an experimental system for understanding species colonization patterns, community formation, and dynamics. The last several years have seen crucial advances in our understanding of biotic colonization after glacier retreats, resulting from the integration of methodological innovations and ecological theories. Recent empirical studies have demonstrated how multiple factors can speed up or slow down the velocity of colonization and have helped scientists develop theoretical models that describe spatiotemporal changes in community structure. There is a growing awareness of how different processes (e.g., time since glacier retreat, onset or interruption of surface processes, abiotic factors, dispersal, biotic interactions) interact to shape community formation and, ultimately, their functional structure through succession. Here, we examine how these studies address key theoretical questions about community dynamics and show how classical approaches are increasingly being combined with environmental DNA metabarcoding and functional trait analysis to document the formation of multitrophic communities, revolutionizing our understanding of the biotic processes that occur following glacier retreat. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Retreat of Mountain Glaciers since the Little Ice Age: A Spatially Explicit Database

“…In the European Alps, for example, glaciers have lost 25-30% of their surface area over the past 60 years, and the rate of ice loss is accelerating rapidly-it has been 200-300% faster in the past two decades than 40 years ago [5][6][7], and similar rates of retreat have been measured in other areas of the world [8]. The biotic and abiotic consequences of glacier retreat have received increasing attention in recent years, with research focusing on the biotic colonization, the formation and evolution of soils along glacier forelands, and the geomorphological hazards related to deglacierization [9][10][11][12][13][14], as well as on the impacts of glacier retreat on meltwater availability and human wellbeing [15,16]. In this context, broad-scale, spatially explicit information on the dynamics of glacier retreat is essential to assess the ecological dynamics of biotic colonization across multiple regions and to develop adequate adaptation and mitigation strategies to reduce geomorphological risks and cope with meltwater scarcity in arid regions.…”

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

“…Glaciers, permafrost, and recently deglaciated areas are ecosystems in their own right and provide permanent or temporary habitat for a variety of specialized taxa from bacteria to vertebrates (Ficetola, 2021;Gobbi et al, 2021). The loss of mountain cryosphere-glacier and permafrost-and changes of the physiognomy of the emerging proglacial landscape threaten local high alpine biodiversity and ecosystems, such as altered hydrological, thermal and bio-geochemical cycles, glacier-fed streams, and glacier forelands (Brighenti et al, 2019).…”

“…In addition, the accelerated pace of warming (Pepin et al, 2015) occurring in high elevations exacerbates the impacts of cryosphere loss, and biodiversity, ecosystem, and hydrological regime changes are lagging behind current climate change (Alexander et al, 2018;Huggel et al, 2015;Milner et al, 2017). The last several years have seen crucial advances in our understanding of biotic colonization and pedogenesis after glacier retreat (Anthelme & Lavergne, 2018;Cauvy-Fraunié & Dangles, 2019;Cuesta et al, 2019;Ficetola, 2021;Hågvar et al, 2020;Khedim et al, 2021). Although hundreds or thousands of years can be required for the full establishment of alpine ecosystems (D'Amico et al, 2017;Eichel, 2019;Erschbamer & Caccianiga, 2016;Temme, 2019), some colonization processes can be surprisingly fast (Anthelme et al, 2021;Benavent-Gonz alez et al, 2019).…”

“…There is a growing amount of literature on glacial and proglacial biodiversity and ecosystem development (Ficetola, 2021); yet we still lack a comprehensive and integrative framework to predict the systematic biodiversity responses to glacier retreat across different mountain regions of the world and the implications for management (Anthelme et al, 2021;Cauvy-Fraunié & Dangles, 2019;Fischer et al, 2019;Lambert et al, 2020). Many cite the urgent need to characterize these emerging (novel proglacial landscapes) and disappearing (glacier and permafrost) habitat types, in order to plan monitoring and management of their biodiversity (Gobbi et al, 2021).…”

“…The process of deglaciation and the emergence of new lands and lakes may pose significant challenges, such as increased natural hazards or changes in water resources (Deline et al, 2021;Linsbauer et al, 2016). But they also represent opportunities for the development of soils and vegetation (Carlson et al, 2014;Egli et al, 2006;Eichel, 2019;Ficetola, 2021;Hock, Rasul, et al, 2019). Organisms can colonize ice-free areas rapidly, and in less than a century, even forests and wetland ecosystems can develop in these former glacier and permafrost lands.…”