Carbon turnover in Alaskan tundra soils : effects of organic matter quality, temperature, moisture and fertilizer


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dc.contributor.author Shaver, Gaius R.
dc.contributor.author Giblin, Anne E.
dc.contributor.author Nadelhoffer, Knute J.
dc.contributor.author Thieler, K. K.
dc.contributor.author Downs, M. R.
dc.contributor.author Laundre, J. A.
dc.contributor.author Rastetter, Edward B.
dc.date.accessioned 2006-06-28T15:49:28Z
dc.date.available 2006-06-28T15:49:28Z
dc.date.issued 2006-02-15
dc.identifier.uri http://hdl.handle.net/1912/1038
dc.description Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Journal of Ecology 94 (2006): 740-753, doi:10.1111/j.1365-2745.2006.01139.x. en
dc.description.abstract Soils of tundra and boreal ecosystems contain large organic matter stocks, typically as a layer of peat that blankets the underlying mineral soil. Despite the low productivity of northern vegetation, organic matter accumulates as peat because decomposition of plant litter is limited by low soil temperatures and often wet, anaerobic conditions (Heal et al. 1981, Jonasson et al. 2001). The total C storage in this northern peat is globally significant, accounting for about one third of the global soil C stock if one includes both tundras and boreal forests (Oechel and Billings 1992, Callaghan et al. 2004a). Soils of northern ecosystems also contain large amounts of organic N that is currently unavailable to plants, but is potentially available and could support higher productivity if mineralized (Shaver et al. 1991, Nadelhoffer et al. 1992, Weintraub and Schimel 2005 a). Controls on soil C stocks and turnover, therefore, are key issues for understanding C exchanges between northern ecosystems and the atmosphere. In this paper, we determine how C losses from peaty soil organic matter are related to its chemical composition, and how that composition changes as the organic matter decomposes. To address these issues we compared four soil organic matter types from three tundra ecosystems near Toolik Lake, Alaska. The comparison included both unfertilized soils and soils that were fertilized annually for eight years before sampling. Under laboratory conditions, we determined how temperature and moisture conditions affect C losses from these organic matter types. The experiment also allowed us to determine how the chemical composition of different types of organic matter changed over four simulated “seasons” of decomposition. The chemical composition or “quality” of soil organic matter is a useful predictor of C turnover (Ågren and Bosatta 1996) although a wide range of definitions and fractionation schemes have been used (Sollins et al. 1999, Harmon and Lajtha 1999). In general, high-quality organic matter is defined as that which is more readily processed by microbes and has a higher rate of decomposition. Fresh plant litter and newly-formed organic matter are expected to be of higher quality than older, more fully decomposed organic matter in which the more labile components have been metabolized (Aerts 1997, Berg 2000). Species composition of the vegetation may also have a strong influence on litter and organic matter “quality” (Berendse 1994, Cornelissen 1996, Hobbie 1996, Hobbie and Gough 2004). In this research we characterized organic matter quality with a widely used sequential extraction procedure (Ryan et al. 1990, Harmon and Lajtha 1999) that breaks soil organic matter into 4 fractions: (1) a “non-polar extractable” (NPE) fraction extracted in methylene chloride, (2) a “water-soluble” (WS) fraction extracted in boiling water, (3) an “acid-soluble’ (AS) fraction extracted in H2SO4, and (4) an “acid-insoluble” (AIS) residue. en
dc.description.sponsorship This research was supported by grants from the US National Science Foundation’s Division of Environmental Biology and Office of Polar Programs to the Marine Biological Laboratory. en
dc.format.extent 290668 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.uri http://dx.doi.org/10.1111/j.1365-2745.2006.01139.x
dc.subject Soil organic matter en
dc.subject Soil carbon en
dc.subject Peat en
dc.subject Organic matter quality en
dc.subject Proximate carbon fractions en
dc.subject Decomposition en
dc.subject Soil respiration en
dc.subject Tundra en
dc.subject Alaska en
dc.subject Climate change en
dc.subject Greenhouse warming en
dc.title Carbon turnover in Alaskan tundra soils : effects of organic matter quality, temperature, moisture and fertilizer en
dc.type Preprint en

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