Repeated experimental fires and window of disturbance in relation to runoff in a Mediterranean shrubland

Abstract

This study is focused on exploring the effect of repeated experimental fires on post-fire runoff generation through a sixteen years monitoring runoff yield from erosion plots (eight years after the first fire and other eight years after the second one) in a Mediterranean shrubland area (La Concordia Experimental Station), considering the fire severity and the post-fire erosive rainfall events. The conceptual framework of the window of disturbance is used to analyze how long the runoff yield in burned plots shows clear differences respect to the unburned ones, as well as, the recovery-rate model for multiple fire events. Results show that the effect of repeated fires on runoff yield is related to a combination of fire severity, climatic conditions (mainly rainfall intensity, I30), soil hydrological properties (infiltration capacity, steady state infiltration and soil water retention capacity), and rate of vegetation recovery. Eight years after the first fire, even though soil hydrological properties are recovered as well as vegetation cover did, rainfall events with I30 ≥20 mm h-1 still promoted differences between burned and control plots. The second post-fire disturbance period was associated with the low vegetation recovery, and also with rainfall events with I30 ≥20 mm h-1 even seven years after the repeated fires.