Description

Forests in the vicinity of the Kenai Peninsula portion of the Chugach National Forest (CNF) in south-central Alaska are of special ecological interest because of their transitional nature between coastal and interior forest types. Fire occurred in the Kenai Mountains during the 20th century, but it was unknown whether fire was an important disturbance process creating structural and landscape diversity within these forests. This report describes three distinct periods of fire frequency - prehistoric (pre 1740), settlement (1741-1913), and post-settlement (1914-1997). Fire reports on the CNF from 1914-1997 were summarized and attributed into a GIS database documenting fire occurrences for the post-settlement period, and a historic fire map was generated for known disturbance burn polygons. A historic land classification document containing maps and photographs revealed widespread fire disturbances at the turn of the 20th century. The fire history disturbances of three isolated, mature forest areas were reconstructed using the age distributions of living trees. Twenty-four historic burns were also examined. Radiocarbon dates of soil charcoal were collected under mature forest stands to document pre-historic fire occurrences. Within the historic burns, remnants of older stumps and isolated residual trees revealed that mature forests existed prior to disturbance. Needleleaf forests adjacent to these historic burns have greater than 200 year old trees. The ages of living Lutz spruce and mountain hemlock within the mature forests sampled are greater than 200 years old, and subsurface soil charcoal is older than 500 years before present. As a result of this study, the role of fire is now recognized as having been an important disturbance process over many millennia in these transitional forest types.