Assessment of 80 years of ancient-badlands restoration in Salda?a, Spain

摘要

This paper presents the history of badland generated in the Salda?a region, Spain; as well as the main responses eight decades after the start of restoration - in terms of vegetation, soil and erosive processes. The restoration consisted of intense reforestation and construction of more than 100 check dams and numerous wattle fences. Presently, the dense vegetation (87% cover) contrasts markedly with the degraded landscape from the early 20th century (5% cover). The thickness of litter and the natural presence of some species (Quercus pyrenaica, Paeonia broteroi and Lactarius deliciosus) clearly indicate the recovery of the site. The development of the forest cover shows that the intervention has the potential to recover almost 90% of the area. There is also evidence of soil regeneration, although some properties (erodibility, resistance to penetration and shear-strength resistance) are not that different between the forested and degraded areas. In the restored zones, runoff is negligible, since a thick layer of moss covers the spillways of all the check dams. Erosion has almost been stopped by the effects of vegetation cover, litter and higher infiltration rates (infiltration rate in forested slopes is 43.4 times greater than in bare slopes). Sediment detachment, such as landslides, mudflows and piping, still occur, but are restricted to the degraded zones. Furthermore, even when sediments are mobilized from the upper degraded hillslopes during the larger storms events (2000-2010), check dams and the lower elevation restored forest-buffers effectively work to reduce the sediment yield into the Carrión River by almost three orders of magnitude (<10~2 mg L~(-1)), compared with data from the 1930s and 1940s (>10~5 mg L~(-1)).