Community assembly in the wake of glacial retreat: A meta‐analysis

Abstract

Ecosystems shaped by retreating glaciers provide a unique opportunity to study the order and timing of biotic colonization, and how this influences the structure of successive ecological communities. In the last century glaciers across most of the cryosphere have receded at an unprecedented pace. Many studies have been published from different parts of the world testing hypotheses about how soil ecosystems are responding to rapid, contemporary deglaciation events. To better understand and draw general conclusions about how soil ecosystems respond to deglaciation, we conducted a global meta‐analysis of 95 published articles focused on the succession of various organisms and soil physicochemical properties in glacier forefields along the chronosequence. Our global synthesis reveals that key soil properties and the abundance and richness of biota follow two conspicuous patterns: (1) some taxa demonstrate a persistent increase in abundance and richness over the entire chronosequence, (2) other taxa increase in abundance and richness during the first 50 years of succession, then gradually decline 50 years onward. The soil properties and soil organisms that are intimately tied to vegetation follow the first pattern, consistent with the idea that aboveground patterns of vegetation can drive patterns of belowground biodiversity. The second pattern may be due to an initial increase and subsequent decline in available nutrients and habitat suitability caused by increased biotic interactions, including resource competition among soil biota. A consensus view of the patterns of historical and contemporary soil ecosystem responses to deglaciation provides a better understanding of the processes that generate these patterns and informs predictions of ongoing and future responses to environmental changes.

Local climate modulates the development of soil nematode communities after glacier retreat

“…With time, the richness of many trophic groups grew (Figure 3), and the functional identity of communities shifted, with an increase of functional richness through the addition of persister taxa (Figure 4). We did not find evidence for distinct successional trajectories among trophic groups, although the rates of richness increase over time differed among them (Table S9), in accordance with previous observations (Doblas‐Miranda et al., 2008; Pothula & Adams, 2022; van Leeuwen et al., 2018).…”

“…To limit issues related to underdetection, we used statistical approaches that consider the possibility of missing rare taxa (Chazdon et al., 1998; Colwell & Coddington, 1994; Gotelli & Colwell, 2011) and verified that our results remained consistent when using metrics that account or do not account for the relative abundance of taxa (Figure S3). Despite these limitations, soil eDNA provides biodiversity estimates and patterns highly consistent with those obtained with traditional approaches (Cantera et al., 2023; Treonis et al., 2018), and the observed changes in nematode communities are generally consistent with the patterns observed by both local‐scale and meta‐analytic studies (Calderón‐Sanou et al., 2019; Devetter et al., 2021; Ji et al., 2013; Lei et al., 2015; Meyer et al., 2021; Pothula & Adams, 2022). Furthermore, the large number of analyzed chronosequences, their global distribution, and the coverage of a broad range of conditions help to smooth the impact of these limitations and reveal emergent signals with high generality (Mestre et al., 2022).…”

“…Previous studies on nematode colonization after glacier retreat reported a range of successional patterns, with variation among trophic groups (Pothula & Adams, 2022) and study areas. For instance, in Lei et al (2015), most of richness increase occurred during the first 50 years, while colonization required much longer time in Devetter et al (2021).…”

“…This dramatic shrinkage will have major impacts on both the biotic and abiotic components of nearby ecosystems and the services they provide (Intergovernmental Panel on Climate Change, 2021; Pothula & Adams, 2022). Deglaciated areas undergo rapid geomorphological changes and are quickly colonized by multiple life‐forms, which in turn determine the dynamics and the functioning of these emerging ecosystems (Ficetola, Marta, et al., 2021; Pothula & Adams, 2022; Sytsma et al., 2023). The loss of mountain glaciers is likely an irreversible process (Intergovernmental Panel on Climate Change, 2021); thus, we urgently need standardized, global‐scale studies on how local to regional differences (e.g., differences in climate) determine the development of different biodiversity components under a changing climate (Crowther et al., 2019; Ficetola, Marta, et al., 2021).…”

Microbial dynamics in soils of the Damma glacier forefield show succession in the functional genetic potential

“…The higher functional diversity in barren soils and biological soil crusts in our study could be explained by the selective pressure imposed by low nutrient and high ultraviolet (UV) conditions (Ni et al, 2022). In the vegetated soils, the successful establishment of highly competitive organisms and the increase in interspecific competition may have led to a decline in diversity (Ortiz‐Alvarez et al, 2018; Pothula & Adams, 2022). In addition, microorganisms stored in glacier habitats (e.g., ice, sub‐ or supraglacial sediments and glacier streams) and released into barren soil after glacier retreat may have contributed to the higher microbial diversity in the initial soils (Rime, Hartmann, & Frey, 2016; Zhong et al, 2021).…”