Relationship of post-fire ground cover to surface fuel loads and consumption in longleaf pine ecosystems

The RxCADRE research team collected multi-scale measurements of pre-, during, and post-fire variables on operational prescribed fires conducted in 2008, 2011, and 2012 in longleaf pine ecosystems in the southeastern USA. Pre- and post-fire surface fuel loads were characterized in alternating pre- and post-fire clip plots systematically established within burn units. Pre- and post-fire surface fuel loads summarized at the plot level were aggregated to estimate absolute consumption (tons/acre) and relative consumption (%) in 28 sample units. Percent cover of green vegetation, non-photosynthetic vegetation (NPV), black char, white ash, and mineral soil were ocularly estimated in plots co-located with the post-fire fuel plots and aggregated to the same 28 sample units. Spearman correlations were calculated between the usually non-normal distributions of ground cover fractions (%) and either surface fuel loads or consumption. There were highly significant correlations between many of these variables, with post-fire white ash cover and exposed mineral soil producing the highest correlations with pre- and post-fire surface fuel loads and consumption. This study provides empirical evidence for the assumption that post-fire white ash is the fire effect most indicative of surface fuel consumption.