Evaluation of FOFEM Fuel Loads and Consumption Estimates in Pine-Oak Forests and Woodlands of the Ouachita Mountains in Arkansas, USA

Abstract

Accurate fuel load and consumption predictions are important to estimate fire effects and air pollutant emissions. The FOFEM (First Order Fire Effects Model) is a commonly used model developed in the western United States to estimate fire effects such as fuel consumption, soil heating, air pollutant emissions, and tree mortality. However, the accuracy of the model in the eastern United States has not been well tested. As a result, managers are turning to locally collected data sets from eastern forests to improve the accuracy of FOFEM and other models. FOFEM lacks local fuel load and consumption data for the Ouachita Mountains, an area with nearly 50,000 ha prescribe burned annually. In this study, we compared fuel loads and consumption using field-collected data with data predicted by FOFEM. We determined fuel loads before and after 15 prescribed fires by sampling live fuels, down woody debris, litter, and duff in three cover types (oak forest, pine-oak forest, and pine woodland) on the Ouachita National Forest in Arkansas. Default estimates of litter and duff fuel load in FOFEM were up to 346 and 1,307% greater than field estimates, respectively. FOFEM estimates of 10-hour, 1-hour, and litter fuel consumption were up to 182, 150, and 46% greater, respectively, than field-measured consumption. These overestimations of fuel load and consumption could result in overpredictions of air pollutant emissions and reduce the area of habitat restored and maintained by prescribed burning as fire managers seek to comply with air quality standards.