10,000 years of climate control over carbon accumulation in an Iberian bog (southwestern Europe)

Abstract

The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs, which are particularly sensitive to projected climate change. In this context, the rate of carbon (C) accumulation in Chao de Veiga Mol, an intact raised bog, was analysed. Changes in the accumulation rate over the past 10 millennia were determined in a peat core of 847 cm in depth, with a high mean rate of peat growth (11 yr cm−1, 0.09 cm yr−1). An age-depth model was generated from 22 14C dates and fallout radionuclides. Chronological, stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago. The total mean C content was 50.2%, and over 10 millennia 583 kg C m−2 accumulated at a mean rate of 35.3 g C m−2 yr−1, with a long-term (apparent) rate of carbon accumulation in the catotelm of 59.9 g C m−2 yr−1. These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere. The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene. They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes. The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies, especially in relation to regional and local modulations in southern Europe.