The seasonal dynamics of amino acids and other nutrients in Alaskan Arctic tundra soils Article Received: 21 November 2003 Accepted: 07 May 2004 DOI:
Cite this article as: Weintraub, M.N. & Schimel, J.P. Biogeochemistry (2005) 73: 359. doi:10.1007/s10533-004-0363-z Abstract.
Past research strongly indicates the importance of amino acids in the N economy of the Arctic tundra, but little is known about the seasonal dynamics of amino acids in tundra soils. We repeatedly sampled soils from tussock, shrub, and wet sedge tundra communities in the summers of 2000 and 2001 and extracted them with water (H
2O) and potassium sulfate (K 2SO 4) to determine the seasonal dynamics of soil amino acids, ammonium (NH 4 +), nitrate (NO 3 −), dissolved organic nitrogen (DON), dissolved organic carbon (DOC), and phosphate (PO 4 2−). In the H 2O extractions mean concentrations of total free amino acids (TFAA) were higher than NH 4 + in all soils but shrub. TFAA and NH 4 + were highest in wet sedge and tussock soils and lowest in shrub soil. The most predominant amino acids were alanine, arginine, glycine, serine, and threonine. None of the highest amino acids were significantly different than NH 4 + in any soil but shrub, in which NH 4 + was significantly higher than all of the highest individual amino acids. Mean NO 3 − concentrations were not significantly different from mean TFAA and NH 4 + concentrations in any soil but tussock, where NO 3 − was significantly higher than NH 4 +. In all soils amino acid and NH 4 + concentrations dropped to barely detectable levels in the middle of July, suggesting intense competition for N at the height of the growing season. In all soils but tussock, amino acid and NH 4 + concentrations rebounded in August as the end of the Arctic growing season approached and plant N demand decreased. This pattern suggests that low N concentrations in tundra soils at the height of the growing season are likely the result of an increase in soil N uptake associated with the peak in plant growth, either directly by roots or indirectly by microbes fueled by increased root C inputs in mid-July. As N availability decreased in July, PO 4 2− concentrations in the K 2SO 4 extractions increased dramatically in all soils but shrub, where there was a comparable increase in PO 4 2− later in the growing season. Previous research suggests that these increases in PO 4 2− concentrations are due to the mineralization of organic phosphorus by phosphatase enzymes associated with soil microbes and plant roots, and that they may have been caused by an increase in organic P availability. Keywords Soil amino acids Dissolved organic nitrogen Arctic soils Tundra soils Tundra nitrogen availability Tundra phosphorus availability Abbreviation TFAA
Total free amino acids
Dissolved organic carbon
Dissolved organic nitrogen
NH 4 +
NO 3 −
PO 4 2−
Dissolved inorganic nitrogen: ammonium + nitrate
References Billings, W.D., Peterson, K.M., Luken, J.O., Mortensen, D.A. 1984 Interaction of increasing atmospheric carbon dioxide and soil nitrogen on the carbon balance of tundra microcosms Oecologia 65 26 29 Google Scholar Bliss, L.C., Matveyeva, N.V. 1992 Circumpolar Arctic vegetation Chapin, F.S. Jefferies, R.L. Reynolds, J.F. Shaver, G.R. Svoboda, J. eds. Arctic Ecosystems in a Changing Climate: An Ecophysiological Perspective Academic Press Orlando 59 89 Google Scholar Chapin, F.S., Johnson, D.A., Mckendrick, J.D. 1980 Seasonal movement of nutrients in plants of differing growth form in an Alaskan tundra ecosystem: implications for herbivory J. Ecol. 68 189 209 Google Scholar Chapin, F.S., McKendrick, J.D., Johnson, D.A. 1986a Seasonal changes in carbon fractions in Alaskan tundra plants of differing growth form: implications for herbivory J. Ecol. 74 707 732 Google Scholar Chapin, F.S., Moilanen, L., Kielland, K. 1993 Preferential use of organic nitrogen for growth by a nonmycorrhizal Arctic sedge Nature 361 150 153 Google Scholar Chapin, F.S., Shaver, G.R., Giblin, A.E., Nadelhoffer, K.J., Laundre, J.A. 1995 Response of Arctic tundra to experimental and observed changes in climate Ecology 76 694 711 Google Scholar Chapin, F.S., Shaver, G.R., Kedrowski, R.A. 1986b Environmental controls over carbon, nitrogen and phosphorus fractions in Eriophorum vaginatum in Alaskan tussock tundra J. Ecol. 74 167 196 Google Scholar Doyle, A.P., Weintraub, M.N., Schimel, J.P. 2004 Persulfate digestion and simultaneous colorimetric analysis of carbon and nitrogen in soil extracts Soil Sci. Soc. Am. J. 68 669 676 Google Scholar Giblin, A.E., Nadelhoffer, K.J., Shaver, G.R., Laundre, J.A., McKerrow, A.J. 1991 Biogeochemical diversity along a riverside toposequence in Arctic Alaska Ecol. Monogr. 61 415 436 Google Scholar Hobbie, S.E. 1996 Temperature and plant species control over litter decomposition in Alaskan tundra Ecol. Monogr. 66 503 522 Google Scholar Hobbie, S.E., Chapin, F.S. 1998 The response of tundra plant biomass, aboveground production, nitrogen, and CO 2 flux to experimental warming Ecology 79 1526 1544 Google Scholar Hobbie, S.E., Shevtsova, A., Chapin, F.S. 1999 Plant responses to species removal and experimental warming in Alaskan tussock tundra Oikos 84 417 434 Google Scholar Jones, D.L., Kielland, K. 2002 Soil amino acid turnover dominates the nitrogen flux in permafrost-dominated taiga forest soils Soil Biol. Biochem. 34 209 219 Google Scholar Kielland, K. 1994 Amino acid absorption by Arctic plants: implications for plant nutrition and nitrogen cycling Ecology 75 2373 2383 Google Scholar Kielland, K. 1995 Landscape patterns of free amino acids in Arctic tundra soils Biogeochemistry 31 85 98 Google Scholar Kielland, K. 1997 Role of free amino acids in the nitrogen economy of Arctic cryptogams Ecoscience 4 75 79 Google Scholar Kummerow, J., Russell, M. 1980 Seasonal root growth in the Arctic tussock tundra Oecologia 47 196 199 Google Scholar Legrand, C., Carlsson, P. 1998 Uptake of high molecular weight dextran by the Dinoflagellate Alexandrium Catenella Aquat. Microb. Ecol. 16 81 86 Google Scholar Lipson, D.A., Nasholm, T. 2001 The unexpected versatility of plants: organic nitrogen use and availability in terrestrial ecosystems [Review] Oecologia 128 305 316 Google Scholar Lipson, D.A., Raab, T.K., Schmidt, S.K., Monson, R.K. 2001 An empirical model of amino acid transformations in an alpine soil Soil Biol. Biochem. 33 189 198 Google Scholar Mckendrick, J.D., Ott, V., Mitchell, G. 1978 Effects of nitrogen and phosphorus fertilization on carbohydrate and nutrient levels in Dupontia fischeri Arctagrostis latifolia Tieszen, L.L. eds. Vegetation and Production Ecology of an Alaskan Arctic Tundra Springer-Verlag Berlin 509 537 Google Scholar Moorhead, D.L., Kroehler, C., Linkins, A., Reynolds, J. 1993 Extracellular acid phosphatase activities in Eriophorum vaginatum tussocks: a modeling synthesis Arctic Alpine Res. 25 50 55 Google Scholar Moorhead, D.L., Linkins, A.E. 1997 Elevated CO 2 alters belowground exoenzyme activities in tussock tundra Plant Soil 189 321 329 Google Scholar Nadelhoffer, K.J., Giblin, A.E., Shaver, G.R., Laundre, J.A. 1991 Effects of temperature and substrate quality on element mineralization in six Arctic soils Ecology 72 242 253 Google Scholar Nordin, A., Schmidt, I.K., Shaver, G.R. 2003 Nitrogen uptake by Arctic soil microbes and plants in relation to soil nitrogen supply Ecology 85 955 962 Google Scholar Pop, E.W., Oberbauer, S.F., Starr, G. 2000 Predicting vegetative bud break in two Arctic deciduous shrub species, Salix pulchra and Betula nana Oecologia 124 176 184 Google Scholar Raab, T.K., Lipson, D.A., Monson, R.K. 1999 Soil amino acid utilization among species of the Cyperaceae: plant and soil processes Ecology 80 2408 2419 Google Scholar Schimel, J.P. 1995 Ecosystem consequences of microbial diversity and community structure Chapin, F.S. Korner, C. eds. Arctic and Alpine Biodiversity: Patterns, Causes, and Ecosystem Consequences Springer-Verlag Berlin 239 254 Google Scholar
Schimel J.P. and Bennet J. 2003. Nitrogen mineralization: challenges of a changing paradigm. Ecology 85(3): 591–602.
Google Scholar Schimel, J.P., Chapin, F.S. 1996 Tundra plant uptake of amino acid and NH 4 + nitrogen in situ: plants compete well for amino acids Ecology 77 2142 2147 Google Scholar Schimel, J.P., Kielland, K., Chapin, F.S. 1996 Nutrient availability and uptake by tundra plants Reynolds, J.F. Tenhunen, J.D. eds. In Landscape Function and Disturbance in Arctic Tundra Springer-Verlag Berlin 203 221 Google Scholar Schulten, H.R., Schnitzer, M. 1998 The chemistry of soil organic nitrogen: a review Biol. Fert. Soil 26 1 15 Google Scholar Serreze, M.C., Walsh, J.E., Chapin, F.S., Osterkamp, T., Dyurgerov, M., Romanovsky, V., Oechel, W.C., Morison, J., Zhang, T., Barry, R.G. 2000 Observational evidence of recent change in the northern high-latitude environment [Review] Climatic Change 46 159 207 Google Scholar Shaver, G.R., Chapin, F.S. 1980 Response to fertilization by various plant growth forms in an Alaskan tundra: nutrient accumulation and growth Ecology 61 662 675 Google Scholar Shaver, G.R., Chapin, F.S. 1986 Effect of fertilizer on production and biomass of tussock tundraAlaskaUSA Arctic Alpine Res. 18 261 268 Google Scholar Shaver, G.R., Chapin, F.S. 1991 Production: biomass relationships and element cycling in contrasting Arctic vegetation types Ecol. Monogr. 61 1 32 Google Scholar Shaver, G.R., Chapin, F.S., Gartner, B.L. 1986 Factors limiting seasonal growth and peak biomass accumulation in Eriophorum vaginatum in Alaskan tussock tundra J. Ecol. 74 257 278 Google Scholar Shaver, G.R., Kummerow, J. 1992 Phenology Resource Allocation and Growth of Arctic Vascular Plants Chapin, F.S. Jefferies, R. Reynolds, J. Shaver, G.R. Svoboda, J. eds. Arctic Ecosystems in a Changing Climate: An Ecophysiological Perspective Academic Press New York 193 212 Google Scholar Smolander, A., Kitunen, V. 2002 Soil microbial activities and characteristics of dissolved organic C and N in relation to tree species Soil Biol. Biochem. 34 651 660 Google Scholar Stevenson, F.J. 1994Humus Chemistry: Genesis, Composition, Reactions Wiley New York Google Scholar Vitousek, P.M., Gosz, J.R., Grier, C.C., Melillo, J.M., Reiners, W.A., Todd, R.L. 1979 Nitrate losses from disturbed ecosystems Science 204 469 474 Google Scholar Weintraub, M.N., Schimel, J.P. 2003 Interactions between carbon and nitrogen mineralization and soil organic matter chemistry in arctic tundra soils Ecosystems 6 129 143 Google Scholar Yu, Z., Zhang, Q., Kraus, T.E.C., Dahlgren, R.A., Anastasio, C., Zasoski, R.J. 2002 Contribution of amino compounds to dissolved organic nitrogen in forest soils Biogeochemistry 61 173 198 Google Scholar