Dong Chen, Cheng Fu, Liza K. Jenkins, Jiaying He, Randi R. Jandt, Gerald V. Frost, Allison Baer, Tatiana V. Loboda

Circumpolar tundra has experienced a greater increase in temperatures compared to any other biome, with a magnitude of the increase nearly three times the global average. Widespread shrubification associated with pronounced observed warming is gradually transforming the tundra ecosystem structure and function. This study confirms that a shrub-dominated fire-biomass positive feedback loop is evident across the Alaskan tundra. Tundra wildfires, especially those with higher severity, play a critical role in boosting the overall “greening” ongoing in many parts of the tundra. However, the fire-vegetation interactions are highly non-uniform and vary greatly within different tundra subregions, a likely consequence of the spatial heterogeneity in vegetation composition, successional trajectories, climatic, and geophysical conditions. Our study highlights the spatial complexity of tundra wildfire regimes as well as their impacts on tundra ecosystems. We thus call for greater attention to fire-vegetation interactions in different ecosystems across the circumpolar tundra domain.