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 affec- ted 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 differ- ences 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.
parallel contour seeding, as a measure of post-fire rehabilitation: The seeding treatment consisted of an herb seed mixture composed of Medicago sativa L., Medicago truncatula Gaertn., Onobrychis viciifolia Scop., Vicia villosa Roth, Agropyron cristatum L. Gaertn., Dactylis glomerata L., Lolium rigidum Gaud., and Phalaris canariensis L. We broadcasted the seed mixture in rows, perpendicularly to the maximal slope (parallel contour seeding) to increase soil roughness as well as plant cover. The sowing rate for the whole mixture was 30 g m 2, with an equivalent weight for each species. The seed mixture was surface applied by hand in autumn, 1 year after a wildfire
|Climate change impacts||Effect of Nbs on CCI||Effect measures|
|Reduced water availability||Positive||soil infiltration, soil moisture, Wetting front depth|
|Freshwater flooding||Positive||Time to runoff (sec), Runoff coefficient (runoff=rainfall ratio, in percent- age)|
|Reduced water quality||No effect||Electrical Conductivity, pH|
|Soil erosion||Positive||soil loss rate (soil loss (g m 2 h 1)), sediment concentration (g/L)|
arid central Ebro Valley (NE Spain) (200–300 m. a.s.l., about 41 300 N and 0 180 E)