Prescribed Burning to Protect Large Diameter Pine Trees from Wildfire - Can We Do It Without Killing the Trees We're Trying to Save?
Hood S, Reardon J, Smith S, Cluck D. 2007. Prescribed Burning to Protect Large Diameter Pine Trees from Wildfire - Can We Do It Without Killing the Trees We're Trying to Save?. Project #JFSP# 03-3-2-04. Lassen National Forest, Eagle Lake District,
Prescribed burning to reduce fuel in some areas with large diameter and old-growth trees is causing significant mortality of these high-value trees even with low intensity fires. A probable cause is the extended burning of large duff accumulations resulting from 100 years of fire exclusion. Burning when duff moistures are low can lead to root mortality and basal girdling from consumption of the duff mounts, which may then lead to tree mortality. Our project objectves were (1) determine if removal of th elitter and duff by raking around the base of large-diameter pine trees will increase their survivability when exposed to prescribed fire, (2) estimate time required to complete raking treatment, and (3) develop relationships between duff characteristics (depth, moisture content, mineral content) and duff consumption. This final report contains 3-post-fire year results for the LVNP site and 2-post fire year results for the LNF sites (as measured by number of growing seasons since fire). We found no significant differences in tree mortality between raked and unraked trees 2 years after the prescribed burns on the Lassen National Forest and 3 years after the burn on the Lassen Volcanic National Park. Raking reduced cambium injury and red turpentine beetle attacks in the burn units. The average time to rake duff around the first 60 am (2 ft) to mineral soil was 16 minutes/person. Raking time depended on the depth of the duff mound. Laboratory tests suggests that sustained smoldering of Jeffrey pine duff occurs above 40-50 moisture content and 65-85% for ponderosa pine.
- Type
- Unpublished Report
- Authors
- Hood, Sharon; Reardon, James; Smith, Sheri; Cluck, Danny
- Date of Issue
- 2007-09-28
- Publisher
- Project #JFSP# 03-3-2-04
- Units
- BRCA
- Keywords
- duff mounds, Fuel Reduction, large diameter trees, old-growth trees, Prescribed Burning, survivability