Biodiversity across ecotones in desertificable Mediterranean areas

Ecotones may play an important role in preventing desertification by ensuring a high degree of biodiversity, thus enhancing soil processes which are mainly mediated by soil fauna and,therefore, soil creation and structuration. In order to detect whether this effect exists in selected desertification-prone Mediterranean areas, the across-groups diversity of soil fauna, the relationship between the fauna and the soil matrix components, and the relation to above-ground vegetation, were studied using new integrated research methods on ECfunded Project Ecotones. Transects were made across ecotones between pine forests and shrublands in Navarra (Spain) and Sicily (Italy). Vegetation was mapped and soil cores were taken. Pedological analyses were done. Soil matrix units were characterised, measured and separated from the cores, and total fauna including arthropods and nematodes was extracted from each unit. Recognisable taxa were classified to species level. Trophic analyses were made. Various diversity and ecological parameters were calculated and data were analysed. Results show that the ecotone effect does exist, ecotone soil samples being generally more rich and diverse that either pine forest or barren soil outside the forest. Soil is being actively created by selected organisms under the ecotone. Certain Mediterranean shrubs seem to play a most important role in providing adequate microclimatic and energy input conditions for the soil engineers. This study may lead to a better understanding of the soil creation processes and to more efficient procedures for both ecosystem recovery following agricultural usage abandonment and reforestation practices, by reducing topsoil erosion risk through maximisation of the ecotone effect.