Pre-wildfire management treatments interact with fire severity to have lasting effects on post-wildfire vegetation response
The authors sampled plots eight years post-wildfire that had been thinned and burned under prescription prior to the Rodeo-Chediski fire to examine differences between areas that burned at high and low severity with or without treatments pre-fire. They specifically examined post-fire species composition, exotic species response, and ponderosa pine regeneration.
The authors found that in areas burned at high severity understory plant cover was greater than in low-severity burned areas, likely due to the increases in resources made available after the death of mature, overstory trees. Exotic plant cover was also greater in areas that burned at high severity, but generally the cover was minimal (< 2%). Areas that had been treated prior to the wildfire had significantly higher ponderosa pine regeneration. The difference between regeneration in treated versus untreated areas was larger for areas burned at high severity. The authors suggest this is due to the greater heterogeneity of patch sizes of high severity fire that were created due to the treatments, allowing for a shorter distance to seed source to facilitate regeneration.