Fig. 1

The landscape-level effect hypothesis posits that fuel treatments can affect wildfire behavior outside of their footprint (i.e., in untreated areas). To test this hypothesis, a study must quantify a link between conditions within fuel treatments and some metric of fire behavior or effect outside of the treatment footprint. In both A and B, the dark line represents the perimeter of a wildfire and the dark circles within each perimeter represent treatment locations. In scenario A, the lighter lines represent contours of influence where the effect of the treatment permeates into untreated areas and decays with distance from treatment boundary. Asymmetric contour shapes reflect the notion that fire behavior outside of treatment boundaries will also be influenced by spatial heterogeneity in biological and physiographic characteristics. White areas represent untreated areas that are unaffected by conditions within the treatments. Scenario A can be interpreted as a prediction of the landscape-level effect hypothesis, that if true, then a spatial relationship exists between within treatment and outside of treatment conditions during a wildfire. Scenario B would not provide the necessary information to test the landscape-level effect hypothesis and is instead site-level; inference of treatment effect is restricted to within treatment boundaries. Text in the right-hand column provides examples of information that can be obtained for both scenarios A and B