U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 38, February 2009


US government work.


A first-of-its-kind study, conducted in a forest of old-growth ponderosa pine and white fi r in Oregon’s Crater Lake National Park, explored the relationships among seasonal prescribed burning, an array of soil attributes, and mycorrhizal fungal fruiting patterns. This three-fold approach not only made the study unique, but also enabled researchers to separate the effects of fi re treatment from the effects of soil attributes on fungal fruiting patterns. The study’s site encompassed three different prescribed burn treatments—applied in the early spring, late spring, and fall of 2002—as well as non-burned control plots. Analyzing statistics with multiple variables, the researchers identifi ed how the treatments affected specifi c soil attributes, which soil attributes affected fungal fruiting patterns, and how the burn treatments affected fungal fruiting patterns. The study revealed that soil attributes—specifi cally carbon-to-nitrogen (C:N) ratios—drive fungal fruiting patterns, and that while fungal communities respond more to C:N ratios in the soil than to burn treatments, prescribed fi re can reduce soil C:N ratios. Most importantly for forest managers concerned with the effects of prescribed fires, the study determined that mycorrhizal fungal communities can withstand even hot prescribed burns in the forests above them.