Relevant effects of vegetal cover and litter on the soil hydrological response of two contrasting Mediterranean hillslopes at the end of the dry season (south of Spain) (pages 1729–1738)

摘要

In Mediterranean regions, hillslopes are generally considered to be a mosaic of sink and source areas that control runoffngeneration and water erosion processes. These hillslopes used to be characterized by a complex hydrological and erosivenresponse combining Hortonian and saturation excess overland flows. The hydrological response of soils is highly dependent onnthe soil surface components (e.g. vegetation patches, bare soil, rock fragment cover, crusts), which each one of them isndominated by a certain hydrological process. One of these soil surface components, not widely considered in studies of soilnhydrology under Mediterranean conditions, is the accumulation of litter beneath shrubs enhancing water repellency in soils. Thisnstudy investigates the influence of soil surface components, especially the litter accumulated beneath Cistus spp., in thenhydrological and erosive responses of soils on two Mediterranean hillslopes having different exposures. The study wasnperformed by means of rainfall simulation experiments and the Water Drop Penetration Time for measuring water repellency ofnsoils, both techniques being carried out at the end of summer (September 2010) with very dry soils. The results indicate that (i)nsoil surface components from the north facing hillslope are characterized by a more uniform hydrological and erosive responsenthan those from the south-facing ones; (ii) the water repellency is more influential on the hydrological response of the northfacingnhillslope due to a greater accumulation of organic rest on the soils as the vegetation cover is also higher; (iii) the southfacingnhillslope seemed to follow the fertility island theory with very degraded bare soil areas, which are the most generated areasnof runoff and mobilized sediments; (iv) the experimental area can be considered as a threshold area between the semiarid andnsubhumid Mediterranean environments, with the south-facing hillslope being comparable with the former and the north facingnone with the latter. Copyright © 2011 John Wiley & Sons, Ltd.