Abstract
ABSTRACTIn this study we assess the total storage, landscape distribution, and vertical partitioning of soil organic carbon (SOC) stocks on the Brøgger Peninsula, Svalbard. This type of high Arctic area is underrepresented in SOC databases for the northern permafrost region. Physico-chemical, elemental, and radiocarbon (14C) dating analyses were carried out on thirty-two soil profiles. Results were upscaled using both a land cover classification (LCC) and a landform classification (LFC). Both LCC and LFC approaches provide weighted mean SOC 0–100 cm estimates for the study area of 1.0 ± 0.3 kg C m−2 (95% confidence interval) and indicate that about 68 percent of the total SOC storage occurs in the upper 30 cm of the soil, and about 10 percent occurs in the surface organic layer. Furthermore, LCC and LFC upscaling approaches provide similar spatial SOC allocation estimates and emphasize the dominant role of “vegetated area” (4.2 ± 1.6 kg C m−2) and “solifluction slopes” (6.7 ± 3.6 kg C m−2) in SOC 0–100 cm storage. LCC and LFC approaches report different and complementary information on the dominant processes controlling the spatial and vertical distribution of SOC in the landscape. There is no evidence for any significant SOC storage in the permafrost layer. We hypothesize, therefore, that the Brøgger Peninsula and similar areas of the high Arctic will become net carbon sinks, providing negative feedback on global warming in the future. The surface area that will have vegetation cover and incipient soil development will expand, whereas only small amounts of organic matter will experience increased decomposition due to active-layer deepening.
Highlights
Cold conditions in permafrost soils hamper organicmatter decomposition by microorganisms, and thereby contribute to the accumulation of large soil organic carbon (SOC) pools. Hugelius et al (2014) estimated that northern circumpolar permafrost soils store about 1,300 ± 200 Pg Carbon (C), which represents nearly twice as much C as currently present in the atmosphere
Based on active-layer depths and SOC stocks, we suggest that projected temperature increases and subsequent deepening of the active layer will not result in the remobilization of large amounts of previously frozen SOC in the Brøgger Peninsula and similar high Arctic environments
The present study provides new data on the total storage as well as spatial and vertical distribution of SOC in the Brøgger Peninsula, a high Arctic mountainous area located in the Svalbard Archipelago
Summary
Cold conditions in permafrost soils hamper organicmatter decomposition by microorganisms, and thereby contribute to the accumulation of large soil organic carbon (SOC) pools. Hugelius et al (2014) estimated that northern circumpolar permafrost soils store about 1,300 ± 200 Pg Carbon (C), which represents nearly twice as much C as currently present in the atmosphere. Hugelius et al (2014) estimated that northern circumpolar permafrost soils store about 1,300 ± 200 Pg Carbon (C), which represents nearly twice as much C as currently present in the atmosphere. The resulting SOM decomposition that is the result of increased microbial activity could release large amounts of carbon dioxide (CO2) and methane (CH4) into the atmosphere and provide a positive feedback on global warming by strengthening the greenhouse effect (Schaefer et al 2014; Schuur et al 2015). The ability to quantify potential greenhouse-gas release from thawing permafrost is limited, among other things, by the uncertainty in distribution and vulnerability of the permafrost SOC stocks in certain undersampled areas of the northern circumpolar region (Mishra et al 2013; Hugelius et al 2014)
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