Soil formation and hydrological evolution of Navazo del Toro small-lake ecosystem, Doñana National Park, Andalusia, Spain

Abstract

The wetlands on the quartz sands aeolian sheet make up one of the ecosystems most recognized and important of the Doñana National Park and Doñana Biological Reserve (South Spain). More than 650 temporal small-lakes have been surveyed in the abundant sand depressions of the aeolian sheet, the most are a hydro-geomorphological dune-small-lake system. This paper studies the pedological diversity around Navazo del Toro (NVT) wetland, one of the biggest temporal small-lakes, through a geopedological catena along 230 m with five soil profiles (NVT-1 to NVT-5). In this context a major focus is displayed on pedological processes and the current hydrological situation of the depression in the Middle-Upper Holocene. The main processes are: translocation of materials (silt and clay) from the Arenosols developed in the slope dune (sand washing processes), sediment accumulation on the dune depression (current wetland bottom), and the development of tirsificated and vertic Luvisols with a chronology of more than 4.255 BP (OSL dating). The water body of the geoecosystem has modified the horizons morphology, creating new hydromorphic (gleyic and stagnic) conditions that have incorporated abundant organic material (sediment of diatoms and sponge spicules) in the higher profile layer and generated an incipient podzolization processes.