Date of this Version
Fire Science Brief, Issue 31, January 2009
At fi rst glance, it may seem that large diameter ponderosa and Jeffrey pine trees would be well-equipped to handle prescribed fire, especially low-intensity burns. They have thick bark and sturdy root systems, and have been around a long time. However, managers have found these high-value trees often die several years after prescribed burning, and researchers want to know how managers and planners can more readily protect these trees. With years of little to no fire, duff accumulation around many of these trees is unprecedented, and some researchers have proposed that burning this deep duff can increase the risk of death to large trees. Raking the duff away from the trees has been proposed to mitigate this problem, but others have argued that raking can harm the trees. Sharon Hood and her colleagues examined the effects of raking versus prescribed burning on large diameter ponderosa and Jeffrey pine trees. They found that raking takes little time, does no harm, and may help trees exposed to prescribed burns. They also found that raking appeared to protect trees from red turpentine beetle attacks, which in turn, later seemed to protect those trees from attacks by primary bark beetles like Jeffrey and western pine beetles. Raking is an important management option when large, high value ponderosa and Jeffrey pine trees may be at risk in prescribed fires.