Modified topsoil islands within patchy Mediterranean vegetation in SE Spain

The spatial distribution of some chemical and physical soil properties was determined in the microenvironment of individual plants of three matorral species (Rosmarinus officinalis L., Stipa tenacissima L., Anthyllis cytisoides L.) in an area of patchy vegetation in south-east Spain. The influence of isolated plants on the chemical and physical status of the topsoil decreased significantly from the plant axis to the bare inter-plant area, giving rise to “islands” of improved topsoil properties beneath each plant (i.e., increased organic matter content and aggregate stability, and decreased bulk density, penetration resistance, shear strength and rock fragment content and cover). The degree and lateral extent of topsoil modification was significantly more pronounced under Rosmarinus and Stipa plants than under Anthyllis shrubs, mainly because of the differential influences of species morphology (i.e., above-ground structure) and components (i.e., canopy and litter covers) on soil properties and erosion/sedimentation processes.