Burn Severity and Terrain: A Spatial Analysis of Forest Fire Burn Severity Trends in the Western United States

Abstract

Differenced normalized burn ratio (dNBR) is a remote sensing technique measuring forest fire burn severity – the post-fire effects on local forest ecology. Understanding how dNBR varies across landscapes as fuel, local weather conditions, and terrain changes provides useful insight into the possible application of dNBR as a data source for fuel consumption and emission modeling. This study evaluated dNBR terrain trends in nineteen forest fires in the Western conterminous United States that burned from 2000 to 2003. Terrain variables tested for possible correlation with dNBR included elevation, slope, aspect, and annual incident solar radiation. Linear results proved significant (p < 0.05) for elevation, slope, and annual incident solar radiation but with low coefficients of determination. Categorical analyses of variance found significant mean differences in all severity classes for each terrain variable. Results demonstrate that terrain controls on dNBR in these fires emerge over large scales as terrain alters local vegetation and fire behavior trends