The impact of vegetation on the stability of dispersive material forming biancane badlands in Val dʹOrcia, Tuscany, Central Italy

The landscape of the Val dʹOrcia is characterized by biancane badlands that have begun to be overgrown with vegetation in recent years, thus causing a loss of the landscapeʹs biodiversity and cultural significance. The aim of this paper is to examine the role of vegetation and associated soil properties on the erodibility and stability of biancane badlands. We attempt to identify factors that clearly distinguish the bare slope area, where erosion is particularly strong, from the vegetated slope area of a typical biancana in the Val dʹOrcia. The data indicate that the vegetated area is characterized by decreased percentages of exchangeable Na+ resulting in a less dispersive character of the soil material in comparison to the bare area. Furthermore, the vegetated area exhibits an increased organic matter content and enhanced water infiltration. Changes in soil properties are probably due to the presence of a continuous vegetation cover that enhances organic matter accumulation, water infiltration, sodium leaching and subsequently soil development. It is concluded that vegetation plays a crucial role in altering soil properties to form more stable slope conditions.