title: Mid-term and scaling effects of forest residue mulching on post-fire runoff and soil erosion.
abstract: Mulching is an effective post-fire soil erosion mitigation treatment. Experiments with forest residue mulch have demonstrated that it increased ground cover to 70% and reduced runoff and soil loss at small spatial scales and for short post-fire periods. However, no studies have systematically assessed the joint effects of scale, time since burning, and mulching on runoff, soil loss, and organic matter loss. The objective of this study was to evaluate the effects of scale and forest residue mulch using 0.25m2micro-plots and 100m2slope-scale plots in a burnt eucalypt plantation in central Portugal. We assessed the underlying processes involved in the post-fire hydrologic and erosive responses, particularly the effects of soil moisture and soil water repellency. Runoff amount in the micro-plots was more than ten-fold the runoff in the larger slope-scale plots in the first year and decreased to eight-fold in the third post-fire year. Soil losses in the micro-plots were initially about twice the values in the slope-scale plots and this ratio increased over time. The mulch greatly reduced the cumulative soil loss measured in the untreated slope-scale plots (616gm-2) by 91% during the five post-fire years. The implications are that applying forest residue mulch immediately after a wildfire can reduce soil losses at spatial scales of interest to land managers throughout the expected post-fire window of disturbance, and that mulching resulted in a substantial relative gain in soil organic matter.
authors.affiliation: Centre for Environmental and Maritime Studies (CESAM), Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: sergio.alegre@ua.pt.
authors.forename: Sergio Alegre
authors.initials: SA
authors.lastname: Prats
authors.affiliation: School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton,, MI 49931, USA.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Wagenbrenner
authors.affiliation: Centre for Environmental and Maritime Studies (CESAM), Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Martinho António Santos
authors.initials: MAS
authors.lastname: Martins
authors.affiliation: Centre for Environmental and Maritime Studies (CESAM), Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Maruxa Cortizo
authors.initials: MC
authors.lastname: Malvar
authors.affiliation: Centre for Environmental and Maritime Studies (CESAM), Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Jan Jacob
authors.initials: JJ
authors.lastname: Keizer
keywords: Eucalypt; Mulch; Runoff; Scale; Soil loss; Soil water repellency; Wildfire