PREDICTING LATE-SUCCESSIONAL FIRE REFUGIA PRE-DATING EUROPEAN SETTLEMENT IN THE WENATCHEE MOUNTAINS

Fires occur frequently in dry forests of the Inland West. Fire effects vary across the landscape, reflecting topography, elevation, aspect, slope, soils, and vegetation attributes. Patches minimally affected by successive fires may be thought of as 'refugia', islands of older for est in a younger forest matrix. Refugia support species absent within the landscape matrix. Our goal was to predict the occurrence of pre-se ttlement refugia using physiographic and topographic variables. We eva luated 487 plots across a 47 000 ha landscape using three criteria to identify historical fire refugia: different structure from surrounding matrix; different fire regime from surrounding matrix; presence of ol d individuals of fire-intolerant tree species. Several combinations of aspect, elevation, and topography best predicted refugial presence. L ess than 20% of the pre-settlement landscape was identified as histori cal fire refugia. Refugia were not connected except by younger stands within the matrix. Current management goals of increasing amounts and connectivity of old, refugia-like forests for the benefit of species a ssociated with late-successional habitat increase the risk of insect a nd pathogen outbreaks and catastrophic wildfires. (C) 1997 Elsevier Sc ience B.V.