Changes Over Time in Fuel-Loading Associated with Spruce Beetle-Impacted Stands of the Kenai Peninsula, Alaska


Bethany Schulz

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Alaska white, Lutz, and Sitka spruce (Picea glauca [Moench] Voss, P. x lutzii Little, and P. sitchensis (Bong.) Carr.) forests are subject to mortality from a variety of causes such as wind, disease, fire, and insect outbreaks. Of all the insects, the spruce beetle (Dendroctonus rojipennis Kirby) is the most devastating (Holsten et al. 1991). Ongoing and new infestations currently impact more than 641,000 acres in Alaska, with 295,000 acres located on the Kenai Peninsula in south-central Alaska (USDA 1994). A variety of impacts are associated with spruce beetle infestations. These impacts include, but are not limited to, the loss of merchantable value of killed trees, long-term stand conversion, changes in wildlife habitat, and increase in fire hazard due to increased fuel loading (USDA 1993). Site specific factors must be considered when predicting the degree of impact and planning for treatment of impacted areas. Following an outbreak of spruce budworm (Choristoneurajumiferana [Clem.]) in eastern Canada during the 1960's and 1970's, several studies were conducted to assess fire potential and fire hazard (Stocks 1985; Pech 1993). The mixed conifer forests of central Ontario experienced an abundance of combustible surface and aerial fuels and high fire weather severity, resulting in many fires that were difficult to control (Stocks 1985). In contrast, the pure and mature stands of balsam fir on the Cape Breton Highlands of Nova Scotia had no accumulation of fuels and low fire weather severity; the cool, moist climate of the Highlands hastened the decomposition of dead woody materials (Pech 1993). As the beetle epidemic continues, land managers must assess impacts and design treatments for areas close to human communities. Their decisions affect those living in the area, and fire hazard is often a central concern to the people who live and/or own property adjacent to beetle-impacted stands. A fire behavior analysis was done for the Cooper Landing area of the Kenai Peninsula in 1990 (See 1990) in direct response to the spruce beetle epidemic. Fire behavior analyses require site specific information on fuels, weather conditions, and topography. A major source of fuel load data had been collected in 1987 by the U.S. Forest Service Forestry Sciences Laboratory (FSL) in Anchorage, Alaska (USDA 1987). While this data set included stands in various stages of beetle outbreak, it did not include stands where trees killed by beetles had begun to break or fall to the ground. The analysis was incomplete due to a lack of local information on the changes in fuel loading conditions 15 years after initial infestation. It was recommended that additional fuels data be collected to reflect the changing fuels conditions (See 1990).


This item was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.