Plant–soil interactions underline the development of novel ecosystems after glacier retreat

Abstract. An emblematic symptom of climate change is the retreat of glaciers worldwide. As glaciers retreat, new terrains are exposed to colonization by a variety of organisms, leading to succession in plant communities and changes in soil properties. However, little is known about how the development of novel ecosystems emerging after glacier retreat depends on plant–soil interactions. Here, we investigated how glacier retreat influences the relationships between plant communities and soil functioning. We examined the diversity and structure of plant communities (functional composition, diversity, ecological indicators) and analyzed soil properties (pH, organic carbon, total nitrogen, C/N ratio, texture, available and total elements) along a glacier foreland comprising four stages of glacier retreat. The dominance of plant functional types shifts from herbaceous to shrubs and ultimately trees. Plant diversity initially increases after glacier retreat, along with an increase in soil organic matter and nutrients. Over 120 years, soils acidify at a rate of 0.02 units per year, the C/N ratio increases while plant diversity decreases. These findings provide novel evidence on the geo-ecological processes driving the development of new ecosystems that emerge from glacier retreat. As climate is warming and glaciers are retreating at increasing rates, pioneer herbaceous communities are quickly replaced by coniferous forests. As a result, biodiversity decreases while organic matter accumulation and soil acidity become more pronounced. We highlight that local plant–soil interactions should be the target of biodiversity conservation efforts and landscape management plans aimed at mitigating the impact of glacier extinction on biodiversity and ecological systems.