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

Responses of peat carbon at different depths to simulated warming and oxidizing

“…Both CO 2 and DOC export rates were higher in 0-20 cm than in deeper layers. This result was consistent with other studies (Biasi et al, 2014;Wang et al, 2013) and in agreement with the idea that older soil found in deeper layers contains higher proportions of "recalcitrant" carbon than younger soil at surface (Bosatta and Agren, 1999;Hogg et al, 1992;Knorr et al, 2005;Nadelhoffer et al, 1991). Under the condition of restricted temperature and O 2 (8°C-AN), Rs did not differ much among soils of different depths; under other three conditions where temperature and O 2 were not so restricted, however, CO 2 and DOC export rates were all substantially higher than those of the same depth in 8°C-AN condition.…”

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

“…Based on the long-term climatic data from the Vorkuta station (67 • 48 N, 64 • 01 E, 172 m a. s. l.) for the 1977-2006 period, the mean annual temperature in the region is −5.6 • C, with January being the coldest month (mean temperature −20.4 • C) and July the warmest one (mean temperature 13.0 • C), and an annual precipitation of 501 mm. A more detailed description of the site as well as information on permafrost and carbon storage of the tundra soils of this region can be found in Hugelius et al (2011), Marushchak et al (2011 and Biasi et al (2013).…”

Variation in N2Fixation in Subarctic Tundra in Relation to Landscape Position and Nitrogen Pools and Fluxes

“…Patterned ground features called peat circles (PC), which are bare, round in shape, and characterized by relatively high water content and bulk density, occur on the peat plateaus (Repo et al, 2009, Biasi et al, 2014. The origin of the PCs is still unclear, but it is suggested that permafrost action and associated uplifting of deeper soil layers to the surface are responsible for their development (Repo et al, 2009).…”

“…The origin of the PCs is still unclear, but it is suggested that permafrost action and associated uplifting of deeper soil layers to the surface are responsible for their development (Repo et al, 2009). They are characterized by different availabilities of C and nutrients and dissimilar C and N transformation pathways in soil compared to adjacent vegetated areas underlain by peat and mineral soils (Repo et al, 2009;Marushchak et al, 2011Marushchak et al, , 2013Biasi et al, 2014). Large nitrous oxide (N 2 O) emissions were recently observed in PC (Repo et al, 2009).…”

“…Moss-crust surfaces are often inhabited with cyanobacteria responsible for N 2 fixation (Evans and Johansen, 1999). In addition, PC are rich in available C (Biasi et al, 2014), and therefore we expect that also heterotrophic N 2 fixation can be important to the N budget.…”