Our purpose was to characterize tree regeneration, compositional patterns, and richness, and their relationships to landscape context and topography in four ca. 30-year-old, high-elevation burns in the southern Rocky Mountains. Vegetation and environmental factors were sampled in 200 0.01-ha plots on transects crossing burn edges and stratified by elevation in four large, 1977-1978 subalpine burns east of the Continental Divide in Colorado: Ouzel, a burn near Kenosha Pass, Badger Mountain, and Maes Creek. We utilized mantel tests, mixed-effects models, and randomization tests to assess relationships between vegetation and environment.
Results/Conclusions Three decades after wildfire, plant communities exhibited pronounced compositional shifts across burn edges; compositional turnover across burn edges increased with elevation. Tree regeneration decreased with increasing elevation and distance into burn interiors; concomitant increases in forbs and graminoids were linked to greater light availability. Richness was nearly doubled in high-severity burn interiors due to the persistence of a suite of native species occurring primarily in this habitat. Richness rose with distance into burns but declined with elevation. Only three of 188 plant species encountered were non-native; these were widespread, naturalized species that comprised < 1% total cover. These subalpine wildfires generated considerable long-term increases in diversity at the plant species-, community-, and landscape-level. Fire suppression in such systems inevitably leads to reductions of such diversity. Concerns about post-fire invasion by exotic plants appear unwarranted in remote high-elevation settings.
