Regional and local scale variations in soil organic carbon stocks in West Greenland

Abstract

The soil organic carbon (SOC) pool of the Northern Hemisphere contains about half of the global SOC stored in soils. As the Arctic is exceptionally sensitive to global warming, temperature rise and prolonged summer lead to deeper thawing of permafrost-affected soils and might contribute to increasing greenhouse gas emissions progressively. To assess the overall feedback of soil organic carbon stocks (SOCS) to global warming in permafrost-affected regions the spatial variation in SOCS at different environmental scales is of great interest. However, sparse and unequally distributed soil data sets at various scales in such regions result in highly uncertain estimations of SOCS of the Northern Hemisphere and here particularly in Greenland. The objectives of this study are to compare and evaluate three controlling factors for SOCS distribution (vegetation, landscape, aspect) at two different scales (local, regional). The regional scale reflects the different environmental conditions between the two study areas at the coast and the ice margin. On the local scale, characteristics of each controlling factor in form of defined units (vegetation units, landscape units, aspect units) are used to describe the variation in the SOCS over short distances within each study area, where the variation in SOCS is high. On a regional scale, we investigate the variation in SOCS by comparing the same units between the study areas. The results show for both study areas that SOCS are with 8 kg m -2 in the uppermost 25 cm and 16 kg m -2 in the first 100 cm of the soil, i.e., 3 to 6 kg m -2 (37.5%) higher than existing large scale estimations of SOCS in West Greenland. Our approach allows to rank the scale-dependent importance of the controlling factors within and between the study areas. However, vegetation and aspect better explain variations in SOCS than landscape units. Therefore, we recommend vegetation and aspect for determining the variation in SOCS in West Greenland on both scales.

Warming and Increased Respiration Have Transformed an Alpine Steppe Ecosystem on the Tibetan Plateau From a Carbon Dioxide Sink Into a Source

“…This suggests that soil temperature and SWC may greatly influence the carbon cycle in permafrost‐affected ecosystems, but also that regions may differ in terms of carbon sink and source activities despite similarities in the presence of permafrost or short growing seasons. Other environmental factors may control the overall carbon sink/source capacity, such as ALT (Gries et al., 2017), water table depth (Celis et al., 2017), even net radiation (Shen et al., 2015), or soil physical factors, for example, the aggregate protection (Qin et al., 2019).…”

Using Relationships Between Vegetation and Surface Soil Biogeochemical Properties to Assess Regional Soil Carbon Inventories for South Baffin Island, Nunavut, Canada

“…Prior work in Greenland suggests agreement with our finding that soils underlying graminoid‐dominated vegetation (our wet meadow sites) store more C than shrub‐dominated vegetation (our mesic tundra and polar desert sites) (Bradley‐Cook & Virginia, 2018; Petrenko et al., 2016). However, other work from Greenland found that arctic ecosystems dominated by tall shrubs or wet shrub areas fed by snow beds stored more C than graminoid soils (Elberling et al., 2004; Gries et al., 2020). Given limited data for how vegetation types affect soil C storage in the Arctic, it is clear that more research is required to understand this relationship.…”

“…Vegetation factors such as species composition, density, leaf area index, C:N ratio, and C use efficiency exert control over surface soil C stocks by altering rates of productivity and soil respiration (Atkinston & Treitz, 2012; Lamarque et al., 2023; Mekonnen, Riley, Grant, et al., 2021). However, disagreement remains on which vegetation types store more C: several studies suggest that graminoid and wetland vegetation types store the most soil C in the Arctic (Bradley‐Cook & Virginia, 2018; Horwath Burnham & Sletten, 2010; Palmtag et al., 2015; Petrenko et al., 2016), but other studies have indicated that shrub tundras store more C (Elberling et al., 2004; Gries et al., 2020). In addition to vegetation, soil moisture also affects the vertical distribution of arctic soil C stocks (Gries et al., 2020; Mishra & Riley, 2012; Natali et al., 2015).…”

Uncertainty Quantification of Soil Organic Carbon Estimation from Remote Sensing Data with Conformal Prediction

“…These regions not only have ample vegetation but are also highly diverse (e.g., spruce, pines, etc.). Plant diversity constitutes highly heterogeneous soil carbon inputs due to different litter types and undulated topograph [70]. The different litter types tend to decompose at different rates, contributing to SOC variability in these regions.…”