| Wildland fire is an important and inevitable ecosystem process that can produce both benefits and damages to the environment and to society's interests. Fire managers need indicators of seasonal fire potential to support decision-making. Weather-driven indices and remote sensing are used to indicate when public lands should be closed to recreation, to set priorities on requests for suppression resources, and to conduct prescribed fires under safe conditions. Many fire danger rating and drought indices are available to fire managers. I present a method for evaluation of indices based on fire activity on a percentile and probability basis. Assessment of nine indices for thirteen locations throughout the U.S. showed that the U.S. National Fire Danger Rating System (NFDRS) index, Energy Release Component, fuel model G, performed well for all locations, from Alaska to Florida. Palmer drought indices did not perform well enough to be used as seasonal indicators of fire potential. An important factor affecting changes in seasonal fire potential is live fuel moisture. I use sampled sagebrush foliage live fuel moisture from Nevada to evaluate the NFDRS woody fuel moisture model. I found that the greenup date required by the model is not appropriate for sagebrush. Development of models for live fuel moisture based on five long-term drying indices showed that the model based on 1000h moisture is adequate. I examine vegetation indices derived from satellite data compared to the seasonal sagebrush fuel moisture data. I found that Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) performed better than MODIS Normalized Difference Vegetation Index (NDVI), which in turn was better than the currently used Advanced Very High Resolution Radiometer (AVHRR) NDVI. I suggest that it may be more appropriate to use remote sensing as a general ordinal indication of conditions rather than specifically as fuel moisture as a required input to fire models, and that methods be developed to evaluate spatial seasonal fire potential indicators, comparable to the methods presented for point data. |
