Carbon turnover in Alaskan tundra soils : effects of organic matter quality, temperature, moisture and fertilizer
Shaver, Gaius R.
Giblin, Anne E.
Nadelhoffer, Knute J.
Thieler, K. K.
Downs, M. R.
Laundre, James A.
Rastetter, Edward B.
MetadataShow full item record
KeywordSoil organic matter; Soil carbon; Peat; Organic matter quality; Proximate carbon fractions; Decomposition; Soil respiration; Tundra; Alaska; Climate change; Greenhouse warming
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.
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.
Showing items related by title, author, creator and subject.
Relationships between carbon isotopic composition and mode of binding of natural organic matter in selected marine sediments White, Helen K.; Reddy, Christopher M.; Eglinton, Timothy I. (2007-07)We have investigated the relationships between radiocarbon (14C) and stable carbon (13C) isotopic composition and the different modes of binding of organic matter (OM) present in surficial sediments from near-shore and ...
Impact of circulation on export production, dissolved organic matter, and dissolved oxygen in the ocean : results from Phase II of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2) Najjar, Raymond G.; Jin, X.; Louanchi, F.; Aumont, Olivier; Caldeira, Ken; Doney, Scott C.; Dutay, J.-C.; Follows, Michael J.; Gruber, Nicolas; Joos, Fortunat; Lindsay, Keith; Maier-Reimer, Ernst; Matear, Richard J.; Matsumoto, K.; Monfray, Patrick; Mouchet, Anne; Orr, James C.; Plattner, Gian-Kasper; Sarmiento, Jorge L.; Schlitzer, Reiner; Slater, Richard D.; Weirig, Marie-France; Yamanaka, Yasuhiro; Yool, Andrew (American Geophysical Union, 2007-08-08)Results are presented of export production, dissolved organic matter (DOM) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon-cycle Model Intercomparison Project. ...
Barium in twilight zone suspended matter as a potential proxy for particulate organic carbon remineralization : results for the North Pacific Dehairs, Frank; Jacquet, S.; Savoye, Nicolas; Van Mooy, Benjamin A. S.; Buesseler, Ken O.; Bishop, James K. B.; Lamborg, Carl H.; Elskens, Marc; Baeyens, W.; Boyd, Philip W.; Casciotti, Karen L.; Monnin, C. (2008-01-22)This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22°45' N 158°W; Hawaii; studied during June–July 2004) and ...