Hydrological conditions and carbon accumulation rates reconstructed from a mountain raised bog in the Carpathians: A multi-proxy approach

Knowledge of past local to regional climate variability is a priority research area as the magnitude of climate change at these scales can be greater than at the global level. Peatlands are sensitive to hydro-climate change and represent a significant carbon (C) pool in the terrestrial biosphere. Here, we applied a multi-proxy approach (bulk density, loss on ignition, total organic carbon, testate amoebae, δ13C in Sphagnum, plant macrofossils, pollen and charcoal) and Bayesian statistics to a peat sequence from a mountain ombrogenous bog (Tăul Muced) to explore how changes in hydrological conditions, peat plant composition and disturbances have affected long-term physical peat properties and the rate of C accumulation over the last ca. 8800years. We found that C accumulation at this site ranged from 7 to 105gCm−2yr−1 (mean 23±14gCm−2yr−1). Climatic conditions exerted a direct influence on the peat's plant composition and subsequently affected C accumulation through litter characteristics and abundance, whereas disturbances had a weak effect. Carbon accumulation was greater (31gCm−2yr−1) at times of wetter and warmer conditions when Sphagnum was dominant, and lower (17gCm−2yr−1) during periods of mixed Sphagnum and vascular plant (mainly sedges) growth under drier/unstable hydrological conditions. Future climate projections of warmer temperatures and greater annual precipitation could therefore positively influence the C sink potential of this peatland. On the other hand, increased anthropogenic pressure in the future may negatively impact the C accumulation. Our study strengthens the geographical coverage of proxy reconstructions of past hydrological variability and highlights the carbon-sink capacity of mountain bogs in a so far understudied region.