Abstract
Alterations in microbial mineralization and nutrient cycling may control the long-term response of ecosystems to elevated CO2. Because micro-organisms constitute a labile fraction of potentially available N and are regulators of decomposition, an understanding of microbial activity and microbial biomass is crucial. Tallgrass prairie was exposed to twice ambient CO2 for 8 years beginning in 1989. Starting in 1991 and ending in 1996, soil samples from 0 to 5 and 5 to 15 cm depths were taken for measurement of microbial biomass C and N, total C and N, microbial activity, inorganic N and soil water content. Because of increased water-use-efficiency by plants, soil water content was consistently and significantly greater in elevated CO2 compared to ambient treatments. Soil microbial biomass C and N tended to be greater under elevated CO2 than ambient CO2 in the 5–15 cm depth during most years, and in the month of October, when analyzed over the entire study period. Microbial activity was significantly greater at both depths in elevated CO2 than ambient conditions for most years. During dry periods, the greater water content of the surface 5 cm soil in the elevated CO2 treatments increased microbial activity relative to the ambient CO2 conditions. The increase in microbial activity under elevated CO2 in the 5–15 cm layer was not correlated with differences in soil water contents, but may have been related to increases in soil C inputs from enhanced root growth and possibly greater root exudation. Total soil C and N in the surface 15 cm were, after 8 years, significantly greater under elevated CO2 than ambient CO2. Our results suggest that decomposition is enhanced under elevated CO2 compared with ambient CO2, but that inputs of C are greater than the decomposition rates. Soil C sequestration in tallgrass prairie and other drought-prone grassland systems is, therefore, considered plausible as atmospheric CO2 increases.
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References
Anderson T H and Domsch K H 1986 Carbon link between microbial biomass and soil organic matter. In Proceedings of the Fourth International Symposium on Microbial Ecology. Eds. F Megusar and M Gantar. pp 467–471. Slovene Society for Microbiology, Ljubljana, Yugoslavia.
Bazzaz F A 1990 The response of natural ecosystems to the rising global CO2 levels. Ann. Rev. Ecol. Syst. 21, 167–196.
Binkley D and Hart S C 1989 The components of nitrogen availability assessments in forest soils. Adv. Soil Sci. 10, 57–112.
Cotrufo M F and Ineson P 1995 Effects of enhanced atmospheric CO2 and nutrient supply on the quality and subsequent decomposition of fine roots of Betula pendula Roth. and Picea sitchensis (Bong.) Carr. Plant Soil 170, 267–277.
Crooke W M and Simpson W E 1971 Determination of ammonium in Kjeldahl digests of crops by an automated procedure. J. Sci. Food Agric. 22, 9–10.
Curtis P S, B G Drake and Whigham D F 1989. Nitrogen and carbon dynamics in C3 and C4 estuarine marsh plants grown under elevated CO2 in situ. Oecologia 78, 297–301.
Diaz S, Grime J P, Harris J and McPherson M 1993 Evidence of a feedback mechanism limiting plant response to elevated CO2. Nature 364, 616–617.
Dippery J K, Tissue D T, Thomas R B and Strain B R 1995 Effects of low and elevated CO2 on C3 and C4 annuals. Oecologia 101, 13–20.
Follett R F and Schimel D S 1989 Effect of tillage practices on microbial biomass dynamics. Soil Sci. Soc. Am. J. 53, 1091–1096.
Gorissen A, Van Ginkel J H, Keurentjes J B and Van Veen J A 1995 Grass root decomposition is retarded when grass has been grown under elevated CO2. Soil Biol. Biochem. 127, 117–120.
Goudriaan J 1993 Interaction of ocean and biosphere in their transient responses to increasing atmospheric CO2. Vegetatio 104/105, 329–337.
Hayes D C and Seastedt T R 1987 Root dynamics of tallgrass prairie in wet and dry years. Can. J. Bot. 65, 787–791.
Houghton R A 1993 Is carbon accumulating in the northern temperate zone? Global Biogeochem. Cycles 7, 611–617.
Hunt H W, Trlica M J, Redente R E, Moore J C, Detling J K, Kittell T G F, Walter D E, Fowler M C, Klein D A and Elliott E T 1991 Simulation model for the effects of climate change on temperate grassland ecosystems. Ecol. Modeling 53, 205–246.
Jackson R B and Reynolds H L 1996 Nitrate and ammonium uptake for single and mixed-species communities grown at elevated CO2. Oecologia 105, 74–80.
Jenkinson D S and Powlson D S 1976 The effects of biocidal treatments on metabolism in soil. V. A method for measuring soil biomass. Soil Biol. Biochem. 8, 209–213.
Keeney D R and Nelson D W 1982 Nitrogen-inorganic forms. In Methods of Soil Analysis. Part 2. 2nd edn. Ed. AL Page. Agronomy 9, 643–689.
Kemp R P, Waldecker D G, Owensby C E, Reynolds J F and Virginia R A 1994 Effects of elevated CO2 and nitrogen fertilization pretreatments on decomposition of tallgrass prairie leaf litter. Plant Soil 165, 115–127.
Knapp A K, Hamerlynck E P and Owensby C E 1993 Photosynthetic and water relations responses to elevated CO2 in the C4 grass Andropogon geraradii. Int'l J. Plant Sci. 154 (4), 459–466.
Lal R, Kimble J, Levine E and Whitman C 1995 World soils and the greenhouse effect: An overview. In Soils and Global Change. Eds. R Lal, J Kimble, E Levine and BA Stewart. pp 1–8. CRC Press, Boca Raton FL.
Larigauderie A, Hilbert D W and Oechel W C 1988 Effect of CO2 enrichment and nitrogen availability on resource acquisition and resource allocation in a grass, Bromus mollis. Oecologia 77, 544–549.
Newton P C D 1991 Direct effects of increasing carbon dioxide on pasture plants and communities. N. Z. J. Agr. Res. 34, 1–24.
Norby R J, O'Neill E G and Luxmoore R J 1986 Effects of atmospheric CO2 enrichment on the growth and mineral nutrition of Quercus alba seedlings in nutrient-poor soil. Plant Physiol. 82, 83–89.
Ojima D S, Dirks B O M, Glenn E P, Owensby C E and Scurlock J O 1993. Assessment of a C budget for grasslands and drylands of the world. Wat. Air, Soil Pollut. 70, 95–109.
Owensby C E 1993 Climate change and grasslands: ecosystem-level responses to elevated carbon dioxide. Proc. 17th Int'l. Grasslands Con. 1119–1124.
Owensby C E and Anderson K L 1967 Yield responses to time of burning in the Kansas Flint Hills. J. Range Mange. 20, 12–16.
Owensby C E, Coyne P I, Ham JM, Auen LM and Knapp A K 1993 Biomass production in a tallgrass prairie ecosystem exposed to ambient and elevated CO2. Ecol. Appl. 3, 644–653.
Owensby C E, Ham J M, Knapp A K, Bremer D and Auen L M 1997 Water vapor fluxes and their impact under elevated CO2 in a tallgrass prairie. Global Change Biol. 3, 189–195.
Owensby C E, Ham J M, Knapp A K and Auen L M 1999 Biomass production and species composition change in a tallgrass prairie ecosystem after long-term exposure to elevated atmospheric CO2. Global Change Biol. 5, 497–506.
Rice C W and Garcia F O 1994 Biologically active pools of carbon and nitrogen in tallgrass prairie soil. In Soil Science Society of America, special publication no. 35, 201–208.
Rice C W, Garcia F O, Hampton C O and Owensby C E 1994 Soil microbial response in tallgrass prairie to elevated CO2. Plant Soil 165, 67–74.
SAS Institute Inc. 1996 SAS System for Mixed models, Cary, N.C.
Seastedt T R 1988 Mass, nitrogen and phosphorus dynamics in foliage and root detritus of tallgrass prairie. Ecology 69, 59–65.
Seastedt T R and Hayes D C 1988 Factors influencing nitrogen concentrations in soil water in a North American tallgrass prairie. Soil Biol. Biochem. 20, 725–729.
Stevenson F J and M A Cole 1999 The Carbon Cycle. In Cycles of Soil. Eds. Stevenson and Cole pp 1–45. John Wiley and Sons, New York.
Tans P P, Fung I Y and Takahashi T 1991 Observational constraints on the global atmospheric CO2 budget. Science 247, 1431–1438.
Van Veen J A, Merckx R and Van De Geijn S C 1989 Plant and soil related controls of the flow of carbon from roots through the soil microbial biomass. In Ecology of Arable Land. Eds. M Clarholm and L Bergstrom pp 43–52. Kluwer Academic Publishers, Dordrecht, The Netherlands.
Voroney R P and E A Paul 1984 Determination of kc and kn in situ for calibration of the chloroform fumigation-incubation method. Soil Biol. Biochem. 16, 4–14.
Williams M A 1998 Master's thesis Chp. 3 Kansas State University. The potential for associative nitrogen-fixation and denitrification under elevated CO2.
Zak D R, Pregitzer K R, Curtis P S, Teeri J A, Fogel R and Randlett D L 1993 Elevated CO2 and feedback between carbon and nitrogen cycles. Plant Soil 151, 105–107.
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Williams, M.A., Rice, C.W. & Owensby, C.E. Carbon dynamics and microbial activity in tallgrass prairie exposed to elevated CO2 for 8 years. Plant and Soil 227, 127–137 (2000). https://doi.org/10.1023/A:1026590001307
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DOI: https://doi.org/10.1023/A:1026590001307