Detection of post-fire residuals using high- and medium-resolution satellite imagery

Abstract

Forest fires can burn across large forested areas over short time periods, but they rarely consume all the trees in their path. Fires leave live irregularly shaped patches or rows of mature trees known as "residuals" within the fire perimeter. IKONOS and Landsat Enhanced Thematic Mapper Plus satellite imagery were acquired over two forested areas affected by fire in the northern boreal forest of Alberta. Each image was classified and residuals were detected with greater than 88% accuracy. Residual patches were grouped into nine minimum mapping unit (MMU) classes and area, patch, and shape level metrics were calculated for each group. Analysis of metric results highlighted how the choice of satellite imagery used to characterize and quantify residuals, the size of the MMU used to define the residuals, and human induced land use cover change (LUCC) processes occurring within fire perimeters were interrelated factors that impacted estimates of residual numbers and sizes. Residual metrics calculated in one fire perimeter should therefore be carefully assessed according to local land use and land cover change dynamics before suggesting that residual information captured in any fire perimeter can typify residual patterns elsewhere. Key words: remote sensing, high resolution, medium resolution, satellite imagery, forest fires, wildfire, residual forest islands, geographic information systems (GIS), minimum mapping unit