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

Abstract

Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover’s role for vegetation, plant-animal interactions, permafrost conditions, microbial processes and biogeochemical cycling. We also compare studies of natural snow gradients with snow manipulation studies, altering snow depth and duration, to assess time scale difference of these approaches. The number of studies on snow in tundra ecosystems has increased considerably in recent years, yet we still lack a comprehensive overview of how altered snow conditions will affect these ecosystems. In specific, we found a mismatch in the timing of snowmelt when comparing studies of natural snow gradients with snow manipulations. We found that snowmelt timing achieved by manipulative studies (average 7.9 days advance, 5.5 days delay) were substantially lower than those observed over spatial gradients (mean range of 56 days) or due to interannual variation (mean range of 32 days). Differences between snow study approaches need to be accounted for when projecting snow dynamics and their impact on ecosystems in future climates.

The International Tundra Experiment (ITEX): 30 years of research on tundra ecosystems

“…Taller shrubs usually translate into greater leaf area, which lowers albedo and increases regional warming (Chapin et al 2005). The greater shrub height and volume of branches affects snow distribution and density, and can lead to increased melt rates as branches above the snow absorb solar radiation and contribute to warming the snow pack (Myers-Smith et al 2011;Wilcox et al 2019;Rixen et al 2022). The greater shrub abundance can also affect other trophic levels, with greater forage availability, and will impact decomposition and nutrient cycling through changes in litter quantity and quality (Myers-Smith et al 2011;McLaren et al 2017).…”

“…Arctic and alpine tundra ecosystems form a distinctive biome, characterized by short, cool growing seasons, oligotrophic soils mostly underlain by permafrost, and strong influences of snow regimes and low stature plants (Bliss 1971;Chapin 1983;Billings 1987;Rixen et al 2022). And as latitude and elevation increase there is an increase in the relative importance of bryophytes and lichens and a decrease in the diversity of vascular plants (Bliss and Matveyeva 1992;Walker et al 2005;Lett et al 2022).…”

Summer temperature—but not growing season length—influences radial growth of Salix arctica in coastal Arctic tundra

“…There is increasing evidence that above-ground phenology may be asynchronous with below-ground root growth (Blume-Werry et al 2016Ögren 2017;Liu et al 2022), though root phenology itself may not respond to autumn warming (Schwieger et al 2018). Snow cover insulates shrubs from winter and spring temperatures (Kelsey et al 2020;Rixen et al 2022), andKrab et al (2018) found diverging shrub radial growth responses to winter temperature, spring warming, and snowmelt amongst species. Vaccinium vitis-idaea L. (Ericaceae) grew more with delayed snowmelt with a contrasting reduction in growth in Empetrum nigrum L. (Ericaceae).…”

Summer temperature – but not growing season length – influences radial growth of Salix arctica in coastal Arctic tundra

“…There is increasing evidence that above-ground phenology may be asynchronous with below-ground root growth (Blume Werry et al 2016Ögren 2017;Liu et al 2022) -, though root phenology itself may not respond to autumn warming (Schwieger et al 2018). Snow cover insulates shrubs from winter and spring temperatures (Kelsey et al 2020;Rixen et al 2022), andKrab et al (2018) found diverging shrub radial growth responses to winter temperature, spring warming, and snowmelt among species. Vaccinium vitis idaea -L. (Ericaceae)…”