Vegetation and climate controls on potential CO2, DOC and DON production in northern latitude soils

Climatic change may influence decomposition dynamics in arctic and boreal ecosystems, affecting both atmospheric CO2 levels, and the flux of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) to aquatic systems. In this study, we investigated landscape‐scale controls on potential production of these compounds using a one‐year laboratory incubation at two temperatures (10° and 30 °C). We measured the release of CO2, DOC and DON from tundra soils collected from a variety of vegetation types and climatic regimes: tussock tundra at four sites along a latitudinal gradient from the interior to the north slope of Alaska, and soils from additional vegetation types at two of those sites (upland spruce at Fairbanks, and wet sedge and shrub tundra at Toolik Lake in northern Alaska). Vegetation type strongly influenced carbon fluxes. The highest CO2 and DOC release at the high incubation temperature occurred in the soils of shrub tundra communities. Tussock tundra soils exhibited the next highest DOC fluxes followed by spruce and wet sedge tundra soils, respectively. Of the fluxes, CO2 showed the greatest sensitivity to incubation temperatures and vegetation type, followed by DOC. DON fluxes were less variable. Total CO2 and total DOC release were positively correlated, with DOC fluxes approximately 10% of total CO2 fluxes. The ratio of CO2 production to DOC release varied significantly across vegetation types with Tussock soils producing an average of four times as much CO2 per unit DOC released compared to Spruce soils from the Fairbanks site. Sites in this study released 80–370 mg CO2‐C g soil C−1 and 5–46 mg DOC g soil C−1 at high temperatures. The magnitude of these fluxes indicates that arctic carbon pools contain a large proportion of labile carbon that could be easily decomposed given optimal conditions. The size of this labile pool ranged between 9 and 41% of soil carbon on a g soil C basis, with most variation related to vegetation type rather than climate.

[1]  S. Zimov,et al.  Winter biotic activity and production of CO2 in Siberian soils : a factor in the greenhouse effect , 1993 .

[2]  Juan J. Armesto,et al.  Patterns of Nutrient Loss from Unpolluted, Old‐Growth Temperate Forests: Evaluation of Biogeochemical Theory , 1995 .

[3]  E. Holland,et al.  Uncertainties in the temperature sensitivity of decomposition in tropical and subtropical ecosystems: Implications for models , 2000 .

[4]  Terry V. Callaghan,et al.  On the potential CO2 release from tundra soils in a changing climate , 1999 .

[5]  J. Verhoeven,et al.  Decomposition of Carex and Sphagnum litter in fens: Effect of litter quality and inhibition by living tissue homogenates , 1995 .

[6]  K. Nadelhoffer,et al.  Effects of drainage and temperature on carbon balance of tussock tundra micrososms , 1996, Oecologia.

[7]  Eric S. Kasischke,et al.  The role of fire in the boreal carbon budget , 2000, Global change biology.

[8]  T. Moore,et al.  SOME CONTROLS ON THE RELEASE OF DISSOLVED ORGANIC CARBON BY PLANT TISSUES AND SOILS , 2001 .

[9]  G. Guggenberger,et al.  Sorption of DOM and DOM fractions to forest soils , 1996 .

[10]  P. Sollins,et al.  Water-extractable soil carbon in relation to the belowground carbon cycle , 1997, Biology and Fertility of Soils.

[11]  J. Coulson,et al.  AN INVESTIGATION OF THE BIOTIC FACTORS DETERMINING THE RATES OF PLANT DECOMPOSITION ON BLANKET BOG , 1978 .

[12]  John E. Walsh,et al.  Recent Variations of Sea Ice and Air Temperature in High Latitudes , 1993 .

[13]  J. Sharp,et al.  Determination of total dissolved nitrogen in natural waters1 , 1980 .

[14]  J. Whalen,et al.  Carbon and nitrogen mineralization from light- and heavy- fraction additions to soil , 2000 .

[15]  S. Hobbie.  Temperature and plant species control over litter decomposition in Alaskan tundra , 1996 .

[16]  K. Nadelhoffer,et al.  EFFECTS OF TEMPERATURE AND SUBSTRATE QUALITY ON ELEMENT MINERALIZATION IN SIX ARCTIC SOILS , 1991 .

[17]  J. Aber,et al.  Responses of Trace Gas Fluxes and N Availability to Experimentally Elevated Soil Temperatures , 1994 .

[18]  G. Asner,et al.  Dissolved Organic Carbon in Terrestrial Ecosystems: Synthesis and a Model , 2001, Ecosystems.

[19]  W. McDowell,et al.  Origin, Composition, and Flux of Dissolved Organic Carbon in the Hubbard Brook Valley , 1988 .

[20]  K. Kielland.  Amino Acid Absorption by Arctic Plants: Implications for Plant Nutrition and Nitrogen Cycling , 1994 .

[21]  W. Oechel,et al.  Observational Evidence of Recent Change in the Northern High-Latitude Environment , 2000 .

[22]  M. B. David,et al.  Temperature and moisture effects on the production of dissolved organic carbon in a Spodosol , 1996 .

[23]  W. Parton,et al.  Analysis of factors controlling soil organic matter levels in Great Plains grasslands , 1987 .

[24]  M. Reichstein,et al.  Temperature dependence of organic matter decomposition: a critical review using literature data analyzed with different models , 1998, Biology and Fertility of Soils.

[25]  Oleg A. Anisimov,et al.  Global warming and active-layer thickness: results from transient general circulation models , 1997 .

[26]  D. Walker.  VEGETATION AND ENVIRONMENTAL GRADIENTS OF THE PRUDHOE BAY REGION, ALASKA. , 1985 .

[27]  A. Starfield,et al.  TIME LAGS AND NOVEL ECOSYSTEMS IN RESPONSE TO TRANSIENT CLIMATIC CHANGE IN ARCTIC ALASKA , 1997 .

[28]  Á. Zsolnay,et al.  Geovariability and biodegradability of the water-extractable organic material in an agricultural soil , 1991 .

[29]  Susan E. Trumbore,et al.  Controls over carbon storage and turnover in high‐latitude soils , 2000, Global change biology.

[30]  Jason C. Neff,et al.  Net ecosystem production: A comprehensive measure of net carbon accumulation by ecosystems. , 2002 .

[31]  M. Billett,et al.  A review of the export of carbon in river water: fluxes and processes. , 1994, Environmental pollution.

[32]  F. Chapin,et al.  Siberian CO2 efflux in winter as a CO2 source and cause of seasonality in atmospheric CO2 , 1996 .

[33]  G. Meehl,et al.  High-latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric CO2 , 1996 .

[34]  C. D. Keeling,et al.  Increased activity of northern vegetation inferred from atmospheric CO2 measurements , 1996, Nature.

[35]  F. Stuart Chapin,et al.  Resource Availability and Plant Antiherbivore Defense , 1985, Science.

[36]  P. Vitousek,et al.  Soil carbon pool structure and temperature sensitivity inferred using CO2 and 13CO2 incubation fluxes from five Hawaiian soils , 1997 .

[37]  Kawak Ijen Volcano,et al.  Boreal forest plants take up organic nitrogen , 1998 .

[38]  Georg Kosakowski,et al.  Flow pattern variability in natural fracture intersections , 1999 .

[39]  N. Roulet,et al.  Groundwater flow and dissolved carbon movement in a boreal peatland , 1997 .

[40]  Christopher B. Field,et al.  Increases in early season ecosystem uptake explain recent changes in the seasonal cycle of atmospheric CO2 at high northern latitudes , 1999 .

[41]  M. B. David,et al.  Carbon mobilization from the forest floor under red spruce in the northeastern U.S.A. , 1996 .

[42]  J. M. Bremner,et al.  Relationships between the denitrification capacities of soils and total, water-soluble and readily decomposable soil organic matter , 1975 .

[43]  W. D. Billings.  CARBON BALANCE OF ALASKAN TUNDRA AND TAIGA ECOSYSTEMS: PAST, PRESENT AND FUTURE , 1987 .

[44]  Diane M. McKnight,et al.  The relationship between soil heterotrophic activity, soil dissolved organic carbon (DOC) leachate, and catchment‐scale DOC export in headwater catchments , 1999 .

[45]  K. Nadelhoffer,et al.  Biogeochemical Diversity Along a Riverside Toposequence in Arctic Alaska , 1991 .

[46]  William S. Currie,et al.  Modeling leaching as a decomposition process in humid montane forests , 1997 .

[47]  J. Tenhunen,et al.  Soil nitrogen, microbial biomass, and respiration along an arctic toposequence , 1998 .