Ecogeomorphological consequences of land abandonment in semiarid Mediterranean areas: integrated assessment of physical evolution and biodiversity

Abstract

This paper is based on an integrated assessment of abandoned farmland in the Iberian Southeast, a representative area of rich-biodiversity landscapes subject to strong physical stress and highly sensitive to environmental change. It is framed within the concept of natural reforestation and seeks an integration of physical and biodiversity features relevant for management. In pilot areas of different lithology (marly, limestone, and metamorphic) and abandonment age (< or >20 years), several physical (soil characteristics, evidences of erosion) and biodiversity (flora and birds) indicators have been assessed. It is concluded that these two sets of indicators often follow divergent or contrasting trajectories, particularly in the less coherent substrates where soil degradation and erosion concur with steppic physiognomy and high ornithological value. Lithology conditions the compositional and structural development of woody vegetation, but local landscape degradation can also reduce the pool of potential colonizers. Ecosystem development can be described as the interplay of positive and negative forces acting on physical evolution and biodiversity change. Abandonment per se is not a widely applicable management option but in many instances it can naturally improve soil and vegetation conditions. In more resistant lithologies, succession could lead to landscape homogenization, although recovery is usually slow and can eventually be arrested in stages dominated by a few woody species. Although our results are not generalizable to all semiarid land abandonment, they provide a framework for selecting management measures and for setting the scale and intensity of their application.