Mapping fire regimes across time and space: Understanding coarse and fine-scale fire patterns

Maps of fire frequency, severity, size, and pattern are useful for strategi cally planning fire and natural resource management, assessing risk and eco logical conditions, illustrating change in disturbance regimes through time , identifying knowledge gaps, and learning how climate, topography, vegetat ion, and land use influence fire regimes. We review and compare alternative data sources and approaches for mapping fire regimes at national, regional , and local spatial scales. Fire regimes, defined here as the nature of fir es occurring over an extended period of time, are closely related to local site productivity and topography, but climate variability entrains fire reg imes at regional to national scales. In response to fire exclusion policies , land use, and invasion of exotic plants over the last century, fire regim es have changed greatly, especially in dry forests, woodlands, and grasslan ds. Comparing among and within geographic regions, and across time, is a po werful way to understand the factors determining and constraining fire patt erns. Assembling spatial databases of fire information using consistent pro tocols and standards will aid comparison between studies, and speed and str engthen analyses. Combining multiple types of data will increase the power and reliability of interpretations. Testing hypotheses about relationships between fire, climate, vegetation, land use, and topography will help to id entify what determines fire regimes at multiple scales.