Characterizing and classifying complex fuels — A new approach

In the United States, fire managers have relied on a small number of stylized fuel models for over 30 years (Anderson 1982)—standard descriptions of homogeneous surface fuel constituents associated with specific types of fire behaviour—as inputs to mathematical calculations of surface fire behaviour. Other systems for describing fuels and calculating fire behaviour have been developed for Canada (Forestry Canada Fire Danger Group 1992) and Australia (Cheney and Sullivan 1997). Scientists and managers are seeking more accurate predictions of fire behaviour and fire effects for operational use, planning, and simulations. While categorical descriptors of fuels have served managers reasonably well in the past, improved predictions might require more comprehensive descriptions of fuelbeds (soil organic matter and all live and dead vegetation) that discriminate among fuel components. Regional resource managers challenged scientists at the US Forest Service Pacific Wildland Fire Sciences Laboratory to develop a comprehensive library of measured fuelbeds that would meet their needs for quantifying fuels over a wide range of vegetative types, such as temperate rainforests, dry ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests, juniper (Juniperus spp.) woodlands, and sagebrush (Artemisia spp.). In principle, realistic multistrata fuelbeds could better represent fuels than could stylized models, providing information about the biophysical environment that would be useful to assessment of fire and biological conditions. The Fuel Characteristic Classification System (FCCS) was developed in response to this challenge. A significant component of the FCCS is a large fuelbed library complied from federal agencies and the scientific literature. This data library assembled from ecosystems throughout the United States includes quantitative and qualitative variables for a wide range of structural components. The FCCS could potentially provide input for a variety of applications including fire behaviour, fire effects on ecological components (e.g., standing dead wood and large woody debris), smoke production (e.g., calculation of particulate emissions), and stand dynamics modeling (e.g., stem density and stem sizes). For example, the FCCS fuelbeds are already being used as inputs for calculating fuel consumption and large-scale emissions (Wiedinmyer et al. 2006). The articles in this feature describe and document the key components and applications of the FCCS. Because the FCCS is a substantial departure from traditional fuel inventory and modeling concepts, extensive input has been elicited from scientists and resource managers in North America during development and beta testing. In addition, the FCCS was formally reviewed by a panel of 12 fire scientists in November 2005. Scientists asked important questions about the validity and scientific foundation of the FCCS. For example, could measured fuelbeds better account for differences in fire behaviour and effects than could stylized fuel models? The following articles were revised in response to this extensive review prior to submission for publication and additional peer review.