PRINCIPLE INVESTIGATOR

Sharon Hood, Forester

INTRODUCTION

Prescribed burning to reduce fuel and the potential for high intensity wildfire in areas with large diameter and old-growth trees can result in significant mortality of these high-value trees. A probable cause is the extensive burning of large duff accumulations at the tree bases which has resulted from 100+ years of fire exclusion. Burning this duff can lead to root mortality and basal girdling from long-term duff smoldering. Even with mechanical thinning to reduce ladder fuels and the probability of fire-induced crown injury, the problem of extensive burning of deep duff mounds and below-ground or basal injury still exists. In order for managers to create successful prescribed burn programs that reduce fuel and restore areas to near historical conditions, information is needed about appropriate prescribe fire use in areas with deep duff mounds that limits large diameter tree injury and mortality and methods for duff manipulation that are effective, efficient, and inexpensive. A synthesis on this topic is timely now because prescribed burning as a fuels treatment is more widespread than ever. The chief of the Forest Service has expressed the importance of restoring fire-adapted ecosystems and has urged managers to address this need. Maintaining the relatively few existing stands of large diameter and old-growth trees is integral to restoring many of these ecosystems. Several studies are underway that address the issue of burning in areas with large, old trees having deep duff mounds and examine the impact of burning on tree injury and mortality. The outcome of these studies and other relevant issues needs to be compiled into one resource for managers.

GOALS AND OBJECTIVES

This project will synthesize the literature and current state of knowledge of burning duff mounds and the impact on tree mortality. The synthesis will focus on the process of duff mound consumption leading to tree injury (i.e. cambium injury, root injury, existing fire scars, insect attacks) and possible mortality, and treatments that can reduce tree injury and mortality when burning (i.e. weather conditions, raking, burning snow wells, etc.). It will also include information about duff mound physical properties, how duff burns, and how moisture conditions influence burning.

PROJECT STATUS

This project began in January 2008 and will be completed by June 2009.

FUNDING ORGANIZATION

Joint Fire Science Program #07-S-09

PRODUCTS