Multi-Scale Analysis of the Spatial Distribution of Soil Organic Carbon Stocks in Permafrost-Affected Soils in West Greenland

Abstract

Soils of the northern circumpolar region are a key organic carbon storage strained by global warming. Thawing of permafrost-affected soils from global warming increases greenhouse-gas emissions whose quantification is limited by sparse, uncertain and spatially diverse data of soil organic carbon stocks (SOCS) across the Arctic region, especially in Greenland. The accurate assessment of the effects of global warming requires better understanding of environmental interactions and feedbacks on SOCS which, however, vary spatially and across scales in Arctic environments. Therefore, different scales were selected to identify scale-dependent effects of environmental factors and processes on the SOCS distribution in permafrost-affected soils in Arctic environments, exemplified by two study areas in West Greenland. Three controlling factors (vegetation, landscape, aspect) were used as representation of spatial varying environmental conditions to investigate the spatial SOCS distribution over short distances separately in both areas on the local scale and over a long distance between both areas on the regional scale. Further, the spatial SOCS distribution was analyzed using a set of multi-scale terrain and spatial features representing environmental processes acting parallel but differing in their intensity on the moraine, valley and catchment scale. The soil data set comprises of SOCS from 140 locations distributed over a study area at the coast and at the ice margin of West Greenland being characterized by oceanic and continental climate. On the local scale, the SOCS distribution was best explained by vegetation and aspect as both reflect the importance of wind and solar radiation in both areas. Furthermore, aspect and curvature best mapped the SOCS distribution shaped by water-driven relocation processes on the moraine and valley scale in SISI and wind-induced processes acting parallel on the moraine, valley and catchment scale in RUSS. On the regional scale, differences in the SOCS distribution result from contrasting climate conditions between the coast and the ice margin which both are reflected by differences in the importance of relevant terrain features and scales and vegetation units between both study areas. Consequently, it is recommended to apply multi-scale terrain features in combination with vegetation to address scale-dependent soil-landscape interrelations being essential for spatial analysis of SOCS in West Greenland.