Effectiveness of litter removal in preventing mortality of yellow barked ponderosa pine in northern Arizona

Abstract

Removal of deep litter and duff from the base of mature southwestern ponderosa pine trees is commonly recommended to reduce mortality following prescribed burns, but experimental studies that quantify the effectiveness of such practices in reducing mortality are lacking. Following a pilot study, on each of four sites in northern Arizona we monitored 15-16 sets of 8 matched trees (N=488) on areas designated to be burned and adjacent unburned sites and randomly assigned one of four litter removal treatments: 1) to 9" with raking, 2) to 9" with a leaf blower, 3) to 40" with raking, and 4) no litter removal. By 2-3 years post burn, no trees had died due to the fall prescribed burns, but litter removal prevented most cambial kill and bole char. Litter removal to 9" was as effective in preventing cambial kill and bole char as removal to 40" and there was no difference between removal by raking versus leaf blowing. These results suggest that litter and duff removal is not needed to prevent ponderosa pine mortality following fall prescribed burns, but removal to 9" is adequate to prevent spots of cambial kill or bark char.

Citation

Fowler, James F.; Sieg, Carolyn H.; Wadleigh, Linda; Haase, Sally. 2007. Effectiveness of litter removal in preventing mortality of yellow barked ponderosa pine in northern Arizona. Final Report, Program Project No. 04-2-1-112. Boise, ID: Joint Fire Sciences Program. Online: http://www.firescience.gov/projects/04-2-1-112/project/04-2-1-112_final_report.pdf