U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 140, August 2011


US government work.


Many areas in the western U.S. are being thinned to reduce fire hazard and spread. Often the most economical solution for the disposal of the thinned biomass is to grind and leave the material onsite. These treatments are assumed to reduce the ability of the forest to carry a crown fire, but the effects of the added material on forest ecosystems are poorly known because such treatments do not have a natural analogue. Managers and the public are interested in understanding the impacts of the addition of this woody material on forest ecosystems so they can evaluate the benefi ts against the potential ecological costs of these treatments. The purpose of this study was to understand the ecological effects of mulching treatments in a broadly replicated study in the dominant coniferous forest types for the southern Rocky Mountains and the Colorado Plateau. The study specifi cally targeted the effects on fuel loading, vegetation response (understory, species richness, and exotics), tree regeneration, soil microclimate and soil nitrogen, and carbon storage.