LAND-USE LEGACIES AND SOIL DEVELOPMENT IN SEMINATURAL 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-wood ed sites located in otherwise similar environments in Ireland. Histori cal records and palynological data were used to evaluate vegetation-so il dynamics and land-use history for both site types. Wooded site podz ols were found to have moror moder-like O horizons, a distinctive eluv ial-illuvial sequence and were generally friable and deeply rooted. No n-wooded soils differed in having deeper, more fibrous Of horizons, E horizons with fragipan-like characteristics, and spodic B horizons fre quently containing thin ironpans that restricted vertical rooting. The re were appreciable amounts of mobile organically complexed and inorga nic, poorly crystalline iron, especially in the spodic upper B horizon s of most sites. This suggests that podzolisation was, and continues t o be, a dominant process in virtually all the soils studied. Podzolisa tion may have been initiated by the presence of Pinus and episodic nat ural and/or anthropogenic fires. The Pinus climax occurred approximate ly 8000 years BP and this species persisted regionally to approximatel y 4000 years BP. Though podzolisation is still the dominant soil proce ss at the wooded sites, the presence of oak seems to retard podzolisat ion compared with non-wooded sites, where acidophilous species such as Calluna vulgaris dominate. (C) 1997 Elsevier Science B.V.