Connectivity of forest fuels and surface fire regimes

The connectivity of a landscape can influence the dynamics of disturbances such as fire. In fire-adapted ecosystems, fire suppression may increase the connectivity of fuels and could result in qualitatively different fire pat terns and behavior. We used a spatially explicit forest simulation model de veloped for the Sierra Nevada to investigate how the frequency of surface f ires influences the connectivity of burnable area within a forest stand, an d how this connectivity varies along an elevation gradient. Connectivity of burnable area was a function of fuel loads, fuel moisture, and fuel bed bu lk density. Our analysis isolated the effects of fuel moisture and fuel bed bulk density to emphasize the influence of fuel loads on connectivity. Con nectivity was inversely related to fire frequency and generally increased w ith elevation. However, certain conditions of fuel moisture and fuel bed bu lk density obscured these relationships. Nonlinear patterns in connectivity across the elevation gradient occurred as a result of gradients in fuel lo ads and fuel bed bulk density that are simulated by the model. Changes in c onnectivity with elevation could affect how readily fires can spread from l ow elevation sites to higher elevations.