Wildfire recovery: unraveling forest and grassland dynamics in western Montana

Abstract

Wildfires are increasingly reshaping landscapes in Western Montana, prompting questions about how vegetation responds to fire across varied environmental conditions. These include differences in topography and fire severity across complex terrain in the Bitterroot National Forest. This study evaluates post-fire vegetation dynamics across four wildfire complexes that burned in 2000, focusing on how fire severity, elevation, slope, and aspect influence the recovery of grasslands and forests. Using data from the Monitoring Trends in Burn Severity (MTBS) program and the National Land Cover Database (NLCD), vegetation change was assessed from 2001 to 2020. Spatial analysis in a geographic information system and logistic regression modeling were used to quantify grassland and forest gain, loss, and persistence. I found that grasslands consistently expanded following fire, with high persistence and minimal loss, whereas forests experienced limited recovery and substantial decline, particularly in high severity burn areas. Environmental gradients strongly influenced outcomes, with grassland gain more responsive to fire severity and elevation, and forest recovery constrained across much of the landscape. My findings highlight divergent recovery pathways and underscore the value of spatially explicit models for informing post-fire management. This work provides a foundation for anticipating vegetation shifts under changing fire regimes and supports the development of targeted restoration strategies in fire-affected ecosystems.