The decline of a hidden and expansive microhabitat: the subnivium

Abstract

The subnivium is the seasonal microhabitat at the snow–ground interface and serves as a refuge for a diversity of species. Increasingly warmer winters are disrupting the continuity of snow cover, and likely the stability of the subnivium. To examine how the extent and duration of this sensitive and widespread below‐snow habitat will shift under warming winters, we deployed fully automated winter greenhouses across latitudinal and land‐cover gradients to monitor subnivium conditions under different climate‐change scenarios and predicted subnivium occurrence across the Great Lakes region. In a +3°C warming scenario, we found little change in subnivium extent or duration, whereas a +5°C scenario produced widespread and marked reductions in both extent (loss of 200,000 km2, a 45% decline) and duration (>1 month decline). Although the subnivium appears resilient to moderate future warming, we predict abrupt and extensive changes in response to increased winter warming, which will have sweeping ecological and environmental consequences in high‐latitude ecosystems.

Competitive overlap between martensMartes americanaandMartes caurinaand fishersPekania pennanti: a rangewide perspective and synthesis

“…Further, local winter weather conditions can alter these relationships with snow. A cold consistent winter with deep snowpack produces a high‐quality subnivium, whereas a freeze–thaw cycle through the winter disrupts subnivium formation and stability (Thompson et al 2021), while forming a surface crust that potentially reduces advantages to martens and conveys them to fishers (Fig. 3; Suffice et al 2020).…”

Winters are changing: snow effects on Arctic and alpine tundra ecosystems

“…An increasing number of studies have combined snow manipulations with warming by OTCs (Dorrepaal et al 2004;Weedon et al 2012;Drescher 2014;Suzuki 2014;Weedon et al 2014;Gillespie et al 2016;Christiansen et al 2017;D'Imperio et al 2018;Darrouzet-Nardi et al 2019;Mörsdorf et al 2019;Frei and Henry 2021;Thompson et al 2021). Both treatments can affect plant growth and biogeochemical processes, but can have different effects depending on mechanisms at work.…”

Seasonality drives the survival landscape of a recovering forest carnivore in a changing world

“…Along their southern range boundary, snowpack is projected to continue to decline, leaving only lake effect zones in the Great Lakes Region as snow and subnivium holdouts [8]. Not only is snow contracting spatially, but the snow season is shortening and spring melt is two weeks earlier than 50 years ago [7].…”

“…Climate change is altering abiotic conditions and changes are particularly pronounced across mid-latitudes and during the shoulder seasons [7]. Notably, there have been substantial reductions in snow cover duration, spatial extent and depth, and the formation of the subnivium is projected to decline sharply under future climate scenarios [8]. Changing climate is altering the timing and duration of seasonality that has driven species adaptations and community structure.…”