Land-use legacies and soil development in semi-natural ecosystems in the marginal uplands of Ireland

The relationships between semi-natural oak woodlands and the podzolic nature of their soils were investigated at 14 wooded and nine non-wooded sites located in otherwise similar environments in Ireland Historical records and palynological data were used to evaluate vegetation-soil dynamics and land-use history for both site types. Wooded site podzols were found to have moror moder-like O horizons, a distinctive eluvial-illuvial sequence and were generally friable and deeply rooted. Non-wooded soils differed in having deeper, more fibrous Of horizons, E horizons with fragipan-like characteristics, and spodic B horizons frequently containing thin ironpans that restricted vertical rooting. There were appreciable amounts of mobile organically complexed and inorganic, poorly crystalline iron, especially in the spodic upper B horizons of most sites. This suggests that podzolisation was, and continues to be, a dominant process in virtually all the soils studied. Podzolisation may have been initiated by the presence of Pinus and episodic natural and/or anthropogenic fires. The Pinus climax occurred approximately 8000 years BP and this species persisted regionally to approximately 4000years BP. Though podzolisation is still the dominant soil process at the wooded sites, the presence of oak seems to retard podzolisation compared with non-wooded sites, where acidophilous species such as Calluna vulgaris dominate.