Effect of mineral soil constituents on carbon characteristics of peatlands in aeolian environments of Iceland

The effects of just over a millennium of heavy erosion of dryland soils (Andosols) are ubiquitous in the Icelandic landscape. While lushly vegetated peatlands may appear like pristine oases of resilience in an otherwise degraded landscape, they are impacted by the surrounding soil erosion. Iceland has one of the most active aeolian environments in the world, and emerging evidence suggests that the carbon dynamics of peatlands may be influenced by windborne volcanic deposits. In this study, the impact of increased dust deposition after the settlement of Iceland in c. 870 CE on the mineral pedogenic environment and its interaction with carbon characteristics of Histosols is investigated. This research uses surface soils (0–30 cm) of Histosols from three peatlands, which receive varying amounts of mineral deposition. We analyse datasets of the peatland vegetation characteristics, their carbon structure as derived by 13 C NMR spectroscopy, andic soil properties based on selective extractions of Al, Fe, and Si, and other complementary soil properties. While differences in vegetation characteristics are to some extent reflected by differences in carbon characteristics, the mineral pedogenic environment also seems to play a role here. We find a stronger relation between andic soil properties and carbon characteristics than previously observed in subsoil Histosols. Decomposition of soil organic matter (SOM) in Histosols which are influenced by andic properties seems to be relatively slow, with carbon characteristics dominated by labile carbon compounds, opposed to more rapid degradation of SOM and comparatively great accumulation of recalcitrant carbon compounds in Histosols without notable andic properties.