Wildfire-Driven Forest Conversion in Western North American Landscapes

TLDR

Changing disturbance regimes and climate are eroding forest resilience, increasing the risk that high‑severity fires will convert pre‑fire forests into different forest types or non‑forest vegetation, with lasting impacts on ecosystem services. This article synthesizes evidence of fire‑driven conversion across western North America and evaluates our ability to predict such changes. The authors assess predictive capacity, identify key uncertainties, and propose applied research themes to guide management in a future where pre‑fire forests may not recover.

Abstract

Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high-severity fire, forest recovery may be compromised by lack of tree seed sources, warmer and drier postfire climate, or short-interval reburning. A potential outcome of the loss of resilience is the conversion of the prefire forest to a different forest type or nonforest vegetation. Conversion implies major, extensive, and enduring changes in dominant species, life forms, or functions, with impacts on ecosystem services. In the present article, we synthesize a growing body of evidence of fire-driven conversion and our understanding of its causes across western North America. We assess our capacity to predict conversion and highlight important uncertainties. Increasing forest vulnerability to changing fire activity and climate compels shifts in management approaches, and we propose key themes for applied research coproduced by scientists and managers to support decision-making in an era when the prefire forest may not return.