Arctic sea ice retreat fuels boreal forest advance

Abstract

Climate-induced northward advance of boreal forest is expected to lessen albedo, alter carbon stocks, and replace tundra, but where and when this advance will occur remains largely unknown. Using data from 19 sites across 22 degrees of longitude along the tree line of northern Alaska, we show a stronger temporal correlation of tree ring growth with open water uncovered by retreating Arctic sea ice than with air temperature. Spatially, our results suggest that tree growth, recruitment, and range expansion are causally linked to open water through associated warmer temperatures, deeper snowpacks, and improved nutrient availability. We apply a meta-analysis to 82 circumarctic sites, finding that proportionally more tree lines have advanced where proximal to ongoing sea ice loss. Taken together, these findings underpin how and where changing sea ice conditions facilitate high-latitude forest advance.

The role of the plant microbiome for forestry, agriculture and urban greenspace in times of environmental change

“…Climate change has also caused a northward expansion of boreal forests which replaced tundra, leading to a decrease of surface albedo and altered subsurface carbon stocks, with positive feedback on global warming. The northward migration of forests was notably better correlated with the retreat of sea ice cover than with temperature increase (Dial et al., 2024 ).…”

Comparing assumptions and applications of dynamic vegetation models used in the Arctic-Boreal zone of Alaska and Canada

“…These effects of warming influence vegetation dynamics, and in turn are impacted by changing vegetation properties (figure 1). The ABZ spans boreal and tundra biomes, where these climate effects are manifesting in diverse vegetation shifts such as Arctic shrubification (Myers-Smith et al 2015, Maliniemi et al 2018, Rees et al 2020, altered treeline extent and density (Rees et al 2020, Dial et al 2024, decreased lichen abundance (Elmendorf et al 2012), and shifts in deciduous tree cover (Mack et al 2021, Massey et al 2023.…”