Cascading effects of winter climate change in northern forests: Microclimate, microbes, biogeochemical flux, and vegetation.

Winter climate change is altering snowpack dynamics in northern forests. Snowpack decline disrupts winter soil thermal and hydrological regimes, alters soil microbial activity beneath the snowpack, and triggers cascading effects on vegetation growth and biogeochemical fluxes into the growing season. Despite growing evidence of these changes, the mechanisms underlying these cascade effects and their regional variation remain poorly understood. This review integrates multi-ecosystem-component monitoring results from snow manipulation studies at two contrasting, well-studied northern forest sites-in the northeastern United States and northern Japan-within a unified cascade framework. We also synthesize findings from a broader range of experiments to explore how regional conditions mediate the impacts of reduced snowpack on northern forests. Finally, we discuss key experimental challenges and propose future research directions to improve predictive understanding of winter climate change impacts on northern forest ecosystems.