Ten years of vegetation assembly after a North American mega fire
This paper examines the post-fire recovery, resistance and resilience, of understory vegetation after a mega fire along a gradient of fire severities.
Post-fire resistance to change in community composition decreased with increasing fire severity over a 10-year period. Furthermore, sites that burned at low or moderate severity returned to pre-fire conditions over time, while high severity sites continued to diverge from pre-fire conditions throughout the study period. Conversely, species richness persisted after the fire regardless of fire severity and exceeded pre-fire levels five years after the fire. However, the colonizing species were often different species than existed on the site pre-fire, but communities remained composed of 89% native species. Non-native species also increased with increasing burn severity, but did not dominate any site in the study area.
The authors suggest that although these mega fires are often catastrophic for overstory vegetation, that may not always be the case for the understory in dry conifer forests. If managers can ameliorate fire severity through forest management, thereby allowing areas to burn at low or moderate severities, ponderosa pine ecosystems may mimic historical fire regimes, increasing the resistance and resilience to community composition change post-fire while stimulating understory growth and species richness.