Soil surface properties in Mediterranean mountain ecosystems: Effects of environmental factors and implications of management

Abstract

Understanding soil processes is fundamental to the success of forest restoration programs. We compared different types of soils in Mediterranean mountain forests with respect to their edaphic environments and influence of vegetation cover and lithology. We then used this information to determine the suitability of current forest restoration programs in these ecosystems. Twenty-four surface horizons in forest soils in two zones of contrasting lithology (calcareous and metamorphic) and different types of vegetation cover or management (shrubland, autochthonous forest and reforested forest) were sampled. A set of their essential soil properties were analysed and a series of parameters considered as indicators of surface soil processes was selected: aggregate size, structural stability, water repellency, mineralisation rate and fungal activity. Results confirm that the lithological origins of soils determines the properties defined by the geochemical environment of soilscapes (texture, pH, exchange complex and free oxides), and does not much influence organic properties. On the other hand, the type of plant cover and management do not influence the geochemical properties of the soil decisively, but do maintain a relative control of organic properties, especially those that define their quality (C/N ratio). The variability of surface properties is not well explained by environmental factors, and it is assumed that a large part may be related to the historical use of the soils. The specificity of soilscapes implies differences in vulnerability to forest management: the surface horizons in siliceous environments are more vulnerable than calcareous environments. It is necessary to better characterize soil properties in these forests and accordingly re-evaluate forest restoration efforts with respect to them.