Fire regimes (i.e., the pattern, frequency and intensity of fire in a region) reflect a complex interplay of bottom-up and top-down controls (Lertzman et al., 1998; McKenzie et al., in press). Bottom-up controls include local variations in topographic, fuel and weather factors at the time of a burn (e.g., fuel moisture and continuity, ignition density and local wind and humidity patterns). Bottom-up regulation is manifest as fine-scale spatial and temporal heterogeneity in fire behavior and effects within landscapes subject to the same general climate. Examples include variation in fuel consumption, tree mortality and soil effects, which create complex burn severity legacies that can influence subsequent fires (Collins and Stephens, 2008; Scholl and Taylor, 2010). Climate is the primary top-down control of fire regimes, acting largely through interannual regulation of biomass production, fuel moisture and regional ignition patterns, and control of the geographic distribution of biomes. Top-down regulation leads to spatial and temporal synchrony in fire occurrence beyond scales at which individual fires are likely to spread.