Fire-enhanced runoff generation and erosion are an important concern in recently burnt areas worldwide but
their mitigation has received little public and scientific attention in Portugal. The present study addressed
this knowledge gap for the two principal fire-prone forest types in Portugal, testing the effectiveness of a
type of mulch that is widely available in the study region but has been little utilized and poorly studied so
far. For logistic reasons, two somewhat different forest residue mulches were tested in a eucalypt plantation
(eucalypt chopped bark) and a nearby Maritime Pine stand (eucalypt logging slash). Arguably, however,
more important differences between the two study sites were those in fire severity, resulting in an elevated
litter cover prior to mulching at the pine site but not at the eucalypt site, and in experimental design, with
eight bounded erosion plots of 16 m2 installed at the eucalypt site as opposed to only four at the pine site
(due to its limited size). Mulching was applied four months after the wildfire and two months after installation
of the plots. Rainfall, runoff and sediment and organic matter losses were measured on a 1- to 2-weekly
basis. Mulching proved highly effective at the eucalypt site, on average reducing the runoff coefficient from
26 to 15% and sediment losses from 5.41 to 0.74 Mg ha−1
. This mulching effect was also statistically signifi-
cant, albeit only for the more important runoff and erosion events, and corresponded to a significant role of
litter cover in explaining the variation in runoff and erosion. At the pine site, by contrast, mulching had no
obvious effect. In all probability, this was first and foremost due to the comparatively small amounts of runoff
and sediments produced by the untreated pine plots (5% and 0.32 Mg ha−1
) and, as such, due to the extensive
needle cast following a low severity fire.