Subalpine vegetation pattern three decades after stand-replacing fire: effects of landscape context and topography on plant community composition, tree regeneration, and diversity

Authors


  • Co-ordinating Editor: Dr. Beverly Collins.

  • Coop, J.D. (Corresponding author, jonathancoop@hotmail.com): USDA Forest Service Rocky Mountain Research Station, Fort Collins, CO 80526, USA; Western State College of Colorado, Gunnison, CO 81231, USA
    Massatti, R.T. (rmassatti@gmail.com): USDA Forest Service Rocky Mountain Research Station, Fort Collins, CO 80526, USA; Institute for Applied Ecology, Corvallis, OR 97339, USA
    Schoettle, A.W. (aschoettle@fs.fed.us): USDA Forest Service Rocky Mountain Research Station, Fort Collins, CO 80526, USA.

Abstract

Objective: Our purpose was to characterize vegetation compositional patterns, tree regeneration, and plant diversity, and their relationships to landscape context, topography, and light availability across the margins of four stand-replacing subalpine burns.

Location: Four 1977 to 1978 burns east of the Continental Divide in Colorado: the Ouzel burn, a burn near Kenosha Pass, the Badger Mountain burn, and the Maes Creek burn.

Methods: Vegetation and environmental factors were sampled in 200 0.01-ha plots on transects crossing burn edges, and stratified by elevation. We utilized dissimilarity indices, mixed-effects models, and randomization tests to assess relationships between vegetation and environment.

Results: Three decades after wildfire, plant communities exhibited pronounced compositional shifts across burn edges. 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 roughly 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 increasing elevation. Only three of 188 plant species were non-native; these were widespread, naturalized species that comprised <1% total cover.

Conclusions: These subalpine wildfires generated considerable, persistent increases in plant species richness at local and landscape scales, and a diversity of plant communities. The findings suggest that fire suppression in such systems must lead to reduced diversity. Concerns about post-fire invasion by exotic plants appear unwarranted in high-elevation wilderness settings.

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