Siewert, Matthias Benjamin (2018): High-resolution maps of soil organic carbon for Abisko, northern Sweden [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.886296

Soil organic carbon (SOC) stored in northern peatlands and permafrost-affected soils are key components in the global carbon cycle. This contribution provides maps of SOC in a sub-arctic mountainous peatland environment in the discontinuous permafrost zone for the Stordalen area in the Abisko region, northern Sweden. Four machine-learning techniques were evaluated for SOC quantification: multiple linear regression, artificial neural networks, support vector machine and random forest. The random forest model performed best and was used to predict SOC for several depth increments at a spatial resolution of 1 m (1 × 1 m). A high-resolution (1 m) land cover classification generated for this study is the most relevant predictive variable. The landscape mean SOC storage (0-150 cm) is estimated to 8.3 ± 8.0 kg C m-2 and the SOC stored in the top meter (0-100 cm) to 7.7 ± 6.2 kg C m-2. The predictive modeling highlights the relative importance of wetland areas and in particular peat plateaus for the landscape SOC storage. The total SOC was also predicted at reduced spatial resolutions of 2 m, 10 m, 30 m, 100 m, 250 m and 1000 m and shows a significant drop in land cover class detail and a tendency to underestimate the SOC at resolutions >30 m. This is associated with the occurrence of many small scale wetlands forming local hot-spots of SOC storage that are omitted at coarse resolutions. Sharp transitions in SOC storage associated with land cover and permafrost distribution are the most challenging methodological aspect. However, in this study, at local, regional and circum-Arctic scales the main factor limiting robust SOC mapping efforts is the scarcity of soil pedon data from across the entire environmental space. For the Abisko region, past SOC and permafrost dynamics indicate that most of the SOC is barely 2000 years old and very dynamic. Future research needs to investigate the geomorphic response of permafrost degradation and the fate of SOC across all landscape compartments in post-permafrost landscapes.