Microbial Respiration in Arctic Upland and Peat Soils as a Source of Atmospheric Carbon Dioxide

• Published in: Ecosystems (New York) Vol. 17; no. 1; pp. 112 - 126
• Main Authors: Biasi, Christina, Jokinen, Simo, Marushchak, Maija E, Hämäläinen, Kai, Trubnikova, Tatiana, Oinonen, Markku, Martikainen, Pertti J
• Format: Journal Article
• Language: English
• Published: Boston Springer-Verlag 01.01.2014; Springer Science+Business Media; Springer US; Springer; Springer Nature B.V
• Subjects: Arctic region; Atmospheric carbon dioxide; Bioavailability; Biomedical and Life Sciences; carbon; Carbon content; Carbon cycle; Carbon dioxide; carbon sinks; Climate system; Decomposition; Ecology; Ecosystems; Environmental Management; field experimentation; Forest soils; Geoecology/Natural Processes; Grasslands; Growing season; habitats; Hydrology/Water Resources; Life Sciences; Mineral soils; Organic soils; Peat; Peat soils; Peat-bogs; Peatlands; Permafrost; Plant Sciences; Plateaus; Respiration; Soil mechanics; Soil microbiology; Soil microorganisms; Soil quality; Soil respiration; Soils; Studies; trenching; Tundra; Tundra soils; Tundras; Zoology; Arctic region; Finland; PN, Arctic; trenching; bioavailability of soil carbon; peat soils; microbial respiration; upland soils; isotope partitioning; subarctic tundra; soil respiration; CO
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-013-9710-z

Knowledge on soil microbial respiration (SMR) rates and thus soil-related CO₂ losses from Arctic soils is vital because of the crucial importance of this ecosystem within the global carbon (C) cycle and climate system. Here, we measured SMR from various habitats during the growing season in Russian subarctic tundra by applying two different approaches: ¹⁴C partitioning approach and root trenching. The variable habitats encompassed peat and mineral soils, bare and vegetated surfaces and included both dry and moist ones. The field experiment was complemented by laboratory studies to measure bioavailability of soil carbon and identify sources of CO₂. Differences in bioavailability of soils, measured in the laboratory as basal soil respiration rates, were generally greater than inter-site differences in SMR rates measured in situ, suggesting secondary constraints at field conditions, such as soil C content. There was a tendency towards lower SMR in vegetated peat plateaus compared to upland mineral tundra (on average 137 vs. 185 g CO₂ m⁻² growing season⁻¹, respectively), but no significant differences were found. Surprisingly, the bare surfaces (peat circles) with 3500-year-old C at the surface exhibited about the largest SMR among all sites as shown by both methods. This was related to the general development of peat plateaus in the region, and uplifting of deeper peat with high C content to the surface during the genesis of peat circles. This observation is particularly relevant for decomposition of deeper peat in vegetated peat plateaus, where soil material similar to the bare surfaces can be found. The data indicate that the large stocks of C stored in permafrost peatlands are principally available for decomposition despite old age.