María Teresa Echeverría

Erodibility and Hydrology of Arid Burned Soils: Soil Type and Revegetation Effects

A set of experiments with a rainfall simulator was performed in the field to evaluate the efficiency of parallel contour seeding as a post-fire restoration strategy in the arid central Ebro Valley (NE Spain). Rainfall simulations were conducted in spring, after seeded plant development, on calcareous and gypsiferous soils, with the same experimental design (two-soil treatments—seeded and nonseeded—per two soil types and per nine replicates). The parallel contour seeding treatment increases soil cover and soil surface roughness, which significantly ameliorates the hydrological and erosional response of both calcareous and gypsiferous burned soils. Seeding decreased soil loss, both in calcareous (23-fold) and gypsiferous soils (4-fold). In addition, it decreased the sediment concentration of runoff for calcareous (6-fold) and gypsiferous soils (2-fold) and the runoff coefficient for calcareous (3.5-fold) and gypsiferous soils (1.5-fold). On the other hand, seeding increased the steady state infiltration rate (3-fold), as well as surface soil moisture (1.2-fold) and wetting front depth (2-fold), with a similar order of magnitude for both soils. Time to runoff and runoff quality (electrical conductivity [EC] and pH) were not affected by seeding. Gypsiferous soils had a higher soil loss, runoff coefficient, and EC flow and a lower time to runoff, steady state infiltration rate, and wetting front depth than calcareous soils. Some of these differences were directly related to differences in soil gypsum and carbonate content (i.e., EC and pH of water runoff) and others are related to the proportion of surface soil protection, an indirect effect of soil characteristics. The results suggest that parallel contour seeding is an effective restoration measure with a short-term response that allows conservation of water and soil on recently burned arid lands, especially in situations of high erosion risk as occurs with soils with low plant cover.

Effects of Fire on Vegetation, Soil and Hydrogeomorphological Behavior in Mediterranean Ecosystems

In the Mediterranean context, wildfire has ceased to be a natural ecological factor and has become an anthropic factor of frequent and intense occurrence. Fires cause environmental alterations based the disappearance or modification of the vegetation cover, soil changes and soil hydrogeomorphological behavior. These transformations are mainly concentrated in the immediate aftermath of the fire and are closely linked with fire frequency, fire severity and the period of the year in which the fires occur. A systematic outline of the effects of fire and the factors implicated in the post-fire environmental dynamic is offered. The role of remote sensing methods on fire effects is well known; this chapter also refers to experiences and works on monitoring temporal patterns of vegetation recovery and mapping erosion-sensitive areas