Soil seed banks reveal the legacy of shifting plant assemblages in late-lying alpine snowpatch communities

Abstract

Snowpatch plant communities, which occur in parts of alpine landscapes where snow accumulates and persists well into the summer, are highly sensitive to climate change. The formation of persistent soil seed banks is recognised as a critical component of a plant community’s resilience to a changing environment. However, our understanding of the ecology of snowpatch soil seed banks and their potential role in the persistence of these threatened communities remains limited. To address this knowledge gap, we (1) characterised the density, diversity and composition of snowpatch soil seed banks along a snowmelt gradient (with early, mid, and late melt zones defined); and (2) contrasted their similarity with long-term vegetation surveys (2020, 2013, 2007) to assess the relationship between soil seed banks and standing vegetation over time. We found persistent soil seed banks in all snowmelt zones and that the snowmelt gradient significantly influenced their density, diversity and composition. Species density and diversity in soil seed banks were higher in the early and mid zones compared to the late zone. However, seedlings from the late zone emerged faster and more synchronously than those emerging from the early and mid zones. The species similarity between seed banks and standing vegetation was relatively high in the two most recent surveys (2020, 2013) compared to the initial survey (2007). However, the composition of life forms and regeneration strategies (i.e. sexual or vegetative reproduction) of seedlings that emerged from the soil seed banks was more similar to the composition of the initial standing vegetation survey (2007) than to the more recent surveys (2020, 2013). Our results suggest that although soil seed banks may be changing as the standing vegetation changes, they still have a compositional similarity to historical plant assemblages, contributing to the resilience of these endangered communities to climate change.