Estimating vulnerability of agriculturally used peatlands in north-east Germany to carbon loss based on multi-temporal subsidence data analysis

Abstract

Agriculturally used peatlands are prone to carbon loss and soil degradation. The intensity of the underlying processes differs locally with respect to land management practices as well as hydro-geomorphic setting and soil conditions. A reliable assessment of the site specific vulnerability to carbon loss is important information to enable effective and precise agricultural and environmental policy. In the frame of a research project to derive an updated map of peatland soils for the Federal State of Brandenburg, located in the North-East of Germany, 7725 soil investigations on peatland sites were carried out thereof 3729 were suitable for peatland subsidence analyses. These data, together with extensive legacy data consisting of approx. 246,650 soil profiles, allow for robust carbon loss estimations based on peatland subsidence records. Observed carbon losses amount to 0.234kg/m2∗yr at (presently) uncultivated sites, 0.562kg/m2∗yr for grassland and 0.645kg/m2∗yr for arable land. These figures agree well with recently published data for similar landscapes and land management practices. Taking into account additional information on the initial peat thickness, the type of underlying substrate and the presence or absence of a mineral top layer, a robust site-specific assessment of vulnerability to carbon loss for agriculturally used peatlands has been done. It is shown that >50% of agriculturally used peatlands in Brandenburg are characterized by medium or high vulnerability to carbon loss.