The effect of land use change on soils and vegetation over various lithological formations on Lesvos (Greece)

The effect of land use change, from arable to abandoned pasture, on soil properties and vegetation establishment was studied in hilly areas of the island of Lesvos. The main purpose of this study was to establish key indicators or land parameters that can be used for defining environmentally sensitive areas to desertification. 106 soil sites were selected in fields cultivated or non-cultivated for 40-45 years and measurements related to protection from land degradation after abandonment, such as fertility status (organic matter content, pH, cation exchange capacity (CEC), exchangeable potassium and sodium), water storage capacity (soil water retention characteristics, soil depth), erosion resistance (soil aggregate stability), and vegetation characteristics (plant species, extent of vegetation cover) were conducted. The selected sites were located on a variety of parent materials such as volcanic lava, pyroclastics, ignimbrite, schist-marble, and shale. The obtained data indicated that soil pH, and CEC were slightly affected after abandonment as compared to the cultivated soils. Levels of exchangeable sodium and potassium were higher in cultivated soils. Organic matter content and soil aggregate stability were greatly enhanced in most of the abandoned soils. Physical characteristics of the parent material greatly influenced the establishment of the natural vegetation. A critical minimum soil depth of 25-30 cm was measured. On mole shallow soils, the associated natural perennial vegetation cover was rapidly reduced, under the prevailing climatic conditions of the study area. Reduction of vegetation cover was related to the parent material. Perennial vegetation was not supported at all on soils below a crucial depth, ranging from 4 to 10 cm, depending on the parent material. This study showed that soil depth is the most important parameter which has to be considered in planning land use change from arable to unmanaged pasture under the soil and climatic conditions of the study area. (C) 2000 Elsevier Science B.V. All rights reserved.