Stones resting on the top soil cause heterogeneous patterns of fire-induced water repellency

Abstract

Depending on soil and fire characteristics, soil water repellency (SWR) may be induced, enhanced or destroyed by burning. The spatial pattern of SWR may be extremely heterogeneous as a consequence of the temperature peaks, the variation of fire temperature, the distribution of fuel, or the amount and type of ashes. In this research, we have studied the effect of stone cover and position on the intensity and spatial distribution of fire-induced SWR after low-, moderate- and high-severity fire. Generally, SWR increased with fire severity, but stones did induce some differences and increased the heterogeneity of the spatial distribution of fire-induced SWR. In low-stone-cover areas, SWR from soil surfaces below stones increased respect to non-covered soil surfaces. In areas under high stone cover, SWR increased from non-covered soil surfaces to soil surfaces below stones after low-severity fire. In moderate- and high-severity burnt soils under high stone cover, SWR was more severe than in non-covered soil surface, but no significant differences were observed.