THE SOILS OF PORTOFINO PROMONTORY (NW ITALY): DISTRIBUTION, GENESIS AND PALAEOENVIRONMENTAL IMPLICATIONS.

The coverage of detailed soil maps is commonly limited in Italy, and the available regional soil inventories are obviously not adequate for local land planning strategies. The aim of this research is to map soil units using a Geographical Information System (GIS) approach in the Portofino regional park. Soil micromorphology has been selected as support to the laboratory routine analyses for studying some representative benchmark profiles in order to explain their genesis and to assess their palaeoclimatic significance. The spatial distribution and variability of the most extensive soil types were analysed using a GIS approach and are presented in a 1:10,000-scale soil map with a descriptive legend. We identified six RSGs: Cambisol, Regosol, Leptosol, Luvisol, Acrisol, and Umbrisol. This GIS database was then used to produce three derived maps: soil erodibility factor, spatial distribution of soil organic carbon (SOC) and soil hydrological groups. Deep and highly weathered soils were identified on an ancient erosional surface. These soils are relict palaeosols, products of longer pedogenesis, and are no longer affected by active processes. Polygenetic development of these palaeosols was underlined by micromorphological studies showing relict features reflect climate conditions typical of past interglacial periods which were warmer and more humid than today.