High-resolution records of late Holocene climate change and carbon accumulation in two north-west European ombrotrophic peat bogs

The peat stratigraphy (plant macrofossils, colorimetric humification, pollen/non-pollen microfossils, carbon/nitrogen ratios) of three replicate cores from a raised peat bog in the UK (Walton Moss) and a single core from a raised peat bog in Denmark (Lille Vildmose) were examined in an attempt to investigate the relation between long-term climate change and changes in species composition of the peat-forming vegetation. Nine wet-shifts identified in the monoliths from Walton Moss and Lille Vildmose mainly occurred during periods of increasing atmospheric C-14 content. Because fluctuations in Holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity, the Little Ice Age (LIA) climatic deteriorations registered in both peat bogs were probably driven by changes in solar activity. Climatic deteriorations in the three replicate cores from Walton Moss are not all consistently registered and may reflect the internal variability in the extent of hollow/lawn/hummock microforms within raised peat-bog ecosystems. The lowest carbon accumulation values for the Walton Moss monoliths between ca. cal AD 1300 and 1800 and between ca. cal AD 1490 and 1580 for Lille Vildmose occurred during the course of LIA climatic deteriorations. Peat-bog primary productivity may have been reduced during the LIA owing to lower spring-summer temperatures and shorter growing seasons for the peat-forming plants. Species-specific higher decomposition rates may have also caused the lower carbon accumulation rates in the peat bogs during the LIA. (C) 2002 Elsevier Science B.V. All rights reserved.