Characterizing Fuels in Treated Areas

Small-log utilization or thinning operations followed by a fuel treatment such as prescribed fire can be used to change the composition and structure of fuelbeds, thereby mitigating deleterious fire effects and reducing the potential for catastrophic wildfires in some forested landscapes. We are developing a national system, Fuel Characteristic Classification (FCC), for fuel identification and assessment that accurately depicts the structural complexity and geographical diversity of all fuelbeds including those manipulated by humans. The FCC system can be used to easily assess the effectiveness of fuel manipulation activities. The system is designed to accommodate researchers and managers who operate at a variety of spatial scales. Users can generate a set of fuel characteristics by accessing existing fuelbed descriptions (fuelbed prototypes) that use generic information such as cover type and vegetation form. The system will incorporate a change-agent feature that enables the user to acquire fuelbed characteristics associated with natural and human disturbance such as wildfire, wind, small-log utilization, thinning, and prescribed fire. Fuelbed prototypes will provide the best available data characterizing the kind, quality, and abundance of fuels. Users can accept these default values or modify some or all of them by using more specific information about vegetation and fuel structure and composition. When the user has finished customizing the fuelbed data, the FCC system will calculate or infer quantitative fuel characteristics (i.e., physical, chemical, and structural properties). In addition, the FCC system will compute fuelbed-specific probable fire parameters, and assign a fuel model to run fire behavior software. A large data library will feed the FCC system and will be populated with values acquired from the literature, photo series, fuel inventory reports, and expert knowledge. The Creating Opportunities program (Fritz Demonstration units) and the Fire and Fire Surrogate study (Hungry Bob units) in northeastern Washington and northeastern Oregon, respectively, are two projects that provided critical change-agent fuel information for the data library. These two studies provide data for mixed-conifer and ponderosa pine units that had been harvested for small-log utilization (Fritz), thinned, burned under prescription, or thinned and burned under prescription (Hungry Bob). Mechanical treatment (i.e., small-log utilization or thinning) caused a significant increase in small woody fuels. Application of prescribed fire after thinning reduced small woody fuel amounts to about preharvest levels.