Fire behavior on the forest floor in coastal redwood forests, Redwood National Park

This study was an examination of forest floor characteristics and related fire behavior in the northern range of California's coastal redwood (Sequoia sempervirens) forests. Experimental fires, during the summer and fall of 1986, in stands of redwood located in Redwood National Park, determined the fuel bed characteristics (fuel depth, load, and moisture) and local weather conditions (temperature and relative humidity) necessary to sustain a low intensity ground fire. Elevation and topographic position, and how they influence fuel moisture, emerged as the determining factors related to ease of fire ignition and rates of spread. Fuel depth and load appeared to affect the intensity and duration of the fires and rate of spread. Once favorable burning conditions were determined, a burning window was identified. The lower threshold conditions were relative humidity less than 40 percent and temperature greater than 20°C. The best time of day for burning was mid-afternoon. This burning window was limited to a few day per month. Preliminary equations to predict flame length were developed using multiple regression and compared with Rothermel's Fuel Model "8". Linear regression analysis determined that the created prediction equation was a better predictor of flame length than Rothermel's Model.