**4. Fire effects on soil properties under laboratory–controlled heatings**

Wildfire passage is accompanied by a heat wave and a deposition of ash as a result of biomass combustion (Fig. 6). Fire effects are directly related to the soil type affected as well as fire severity, i.e. the heat reached and the quantity and quality of ashes deposited on soil surface. To test these variables we treated two contrasting soils under laboratory conditions, the most frequently found soils in the semi-arid Central Ebro Valley (NE-Spain), a Calcaric Regosol developed on marls and a Haplic Gipsisol, developed on gypsiferous marls.
