Fire history of ponderosa pine forest in the eastern Cascades, Washington

Wildfires are historically common in the ponderosa pine forests of the eastern Cascade Mountains and are critical for maintaining forest health. These forests have been dramatically modified for approximately the past 100 years by human activities such as fire suppression. The effects of this were not noticed until recently, but in the last several decades it has become evident that these forests are experiencing larger, more devastating fire events, such as the Taylor Bridge and Table Mountain fires. The purpose of this study was to reconstruct the recent fire history of Green Lake, located in Okanogan County, Washington, approximately five miles northwest of the town of Omak, by analyzing macroscopic charcoal in a lake sediment core from the site. The core was analyzed at contiguous one centimeter intervals for the past 1,000 years, and only charcoal particles greater than 125 microns were identified and counted, as they indicate local fires. Charcoal peaks were used for determining past changes in fire frequency. The charcoal record from the past century has been compared with that of the previous 900 years. Preliminary results show fluctuations of charcoal in the past century but a general trend to larger fire events; whereas the (past 400 years) shows smaller fire events. This study furthers our understanding of fire activity in such landscapes.