Proxy climate and vegetation changes during the last five millennia in NW Iberia: Pollen and non-pollen palynomorph data from two ombrotrophic peat bogs in the North Western Iberian Peninsula

Abstract

Pollen and non-pollen palynomorph data are presented from two radiocarbon-dated ombrotrophic peat bogs from the Xistral Mountains in the North Western Iberian Peninsula. The results suggest that vegetation changes over the last five millennia are the result of human disturbance and climate change. Four major periods of forest disturbance are recorded: during the Late Neolithic, Metal Ages, Roman period and culminating in the permanent decline of deciduous forests since the Middle Ages, as agriculture and metallurgy intensified. Records of non-pollen palynomorphs, particularly those derived from fungi, proved to be useful indicators of climate change and human activity. Discriminant and cluster analysis suggest that trends in certain pollen and NPP reflect changes in humidity and to a lesser extent temperature. Cyperaceae and Types 18 and 18b increase during more humid, wet phases, whilst Type 306 increases during drier phases. Various ascospores, derived from coprophilous fungi, complement changes in pollen taxa to infer human activity.