Sediment movement (slopewash and bio-transfer), runoff, and organic matter movement (mainly leaf litter, ash and charcoal) were monitored on ten plots for a six-month period following bushfires in eastern Australia in the 1990s. Plots were installed in areas which had experienced high, moderate and low intensity burns. Although between-plot variability was high, slopewash and organic matter amounts were greatest on the intensely burnt areas, and progressively less on moderate and low intensity burns. In contrast, most leaf litter input from scorched leaf fall was derived from, and collected in, moderately burnt areas. Bio-transfer of sediment (direct downslope surface movement produced by faunal activity) occurred mainly by ant mounding, and was more than ten times greater on moderately burnt areas than on plots having high or low intensity burns. Bio-transfer accounted for approximately 36 per cent of total sediment collected, with this material being recorded least often and in smallest quantities on areas of high intensity burns. Bio-transfer by ant mounding and animal scratchings contributed loose surface sediment for transport by overland flow, disproportionately increasing total sediment movement to plot aprons in areas of moderate intensity burns.

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Abstract. Erosion following fire has the potential to affect water quality, alter soil profiles and detrimentally affect human infrastructure. There is a clear need for environmental assessments to have regard for erosion concerns from prescribed burning. This study focussed on 10 prescribed burns conducted in the Southern Mount Lofty Ranges. Generalised additive modelling was used to determine the main significant environmental variables influencing the presence of sediment movement at 505 field-assessed sites. Sediment movement after the 10 prescribed burns was minor. Fire severity was a highly significant environmental determinant for the presence of sediment movement after prescribed burning. To predict erosion concerns, a suite of environmental variables is more reliable than focusing solely on slope steepness, as occurred before this study. These results indicate that erosion assessments need to consider a range of environmental variables to assess potential erosion and that land managers and scientists need to incorporate spatial sampling designs into erosion assessments.