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11. Contributors

Author

Ackerly, D.D., primary, Arnone, John A., additional, Auen, Lisa M., additional, Bazzaz, F.A., additional, Birrer, A., additional, Björn, L.O., additional, Blum, Herbert, additional, Callaghan, T.V., additional, Campbell, Bruce D., additional, Chiariello, Nona R., additional, Cochran, Robert C., additional, Curtis, Peter S., additional, De Angelis, Paolo, additional, Dhillion, Shivcharn, additional, Field, Christopher B., additional, Fischer, Bernt, additional, Frehner, Marco, additional, Gehrke, C., additional, Gloser, Jan, additional, Grime, J.P., additional, Guillerm, Jean-Louis, additional, Gwynn-Jones, D., additional, Hart, Alan L., additional, Hartwig, Ueli A., additional, Hebeisen, Thomas, additional, Hendrey, George R., additional, Hirose, T., additional, Jasieński, M., additional, Johanson, U., additional, Johnson, Hyrum B., additional, Jones, T. Hefin, additional, Kalisz, Susan, additional, Kingsolver, Joel G., additional, Klus, Dawn Jenkins, additional, Körner, Ch., additional, Kuzminsky, Elena, additional, Lavigne, C., additional, Lawler, Sharon P., additional, Lawton, John H., additional, Leadley, Paul W., additional, Lee, J.A., additional, Lindroth, Richard L., additional, Lüscher, Andreas, additional, Matteucci, Giorgio, additional, Mayeux, Herman S., additional, Naeem, Shahid, additional, Navas, Marie-Laure, additional, Nösberger, Josef, additional, Owensby, Clenton E., additional, Polley, H. Wayne, additional, Poorter, Hendrik, additional, Potvin, Catherine, additional, Reekie, E.G., additional, Reynolds, Heather L., additional, Roumet, Catherine, additional, Roy, Jacques, additional, Sage, Rowan F., additional, Sanders, Ian R., additional, Scarascia-Mugnozza, Giuseppe E., additional, Schmid, B., additional, Sonesson, M., additional, Thomas, S.C., additional, Thompson, Lindsey J., additional, Tischler, Charles R., additional, Tonsor, Stephen J., additional, Tousignant, Denise, additional, Van Kessel, Chris, additional, Weiner, Jacob, additional, Woodfin, Richard M., additional, and Zanetti, Silvia, additional

Published
1996
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15. Soil mineral nitrogen availability was unaffected by elevated atmospheric pCO2 in a four year old field experiment (Swiss FACE)

Author

Gloser, Vit, Je íková, Marta, Lüscher, Andreas, Frehner, Marco, Blum, Herbert, Nösberger, Josef, Hartwig, Ueli, Gloser, Vit, Je íková, Marta, Lüscher, Andreas, Frehner, Marco, Blum, Herbert, Nösberger, Josef, and Hartwig, Ueli

Abstract

The effect of elevated (60 Pa) atmospheric carbon dioxide partial pressure (pCO2) and N fertilisation on the availability of mineral N and on N transformation in the soil of a Lolium perenne L. monoculture was investigated in the Swiss FACE (Free Air Carbon dioxide Enrichment) experiment. The apparent availability of nitrate and ammonium for plants was estimated during a representative, vegetative re-growth period at weekly intervals from the sorption of the minerals to mixed-bed ion-exchange resin bags at a soil depth of 5 cm. N mineralisation was measured using sequential coring and in situ exposure of soil cores in the top 10 cm of the soil before and after the first cut in spring 1997. High amounts of mineral N were bound to the ion exchange resin during the first week of re-growth. This was probably the combined result of the fertiliser application, the weak demand for N by the newly cut sward and presumably high rates of root decay and exudation after cutting the sward. During the first 2 weeks after the application of fertiliser N at the first cut, there was a dramatic reduction in available N; N remained low during the subsequent weeks of re-growth in all treatments. Overall, nitrate was the predominant form of mineral N that bound to the resin for the duration of the experiment. Apparently, there was always more nitrate than ammonium available to the plants in the high N fertilisation treatment for the whole re-growth period. Apparent N availability was affected significantly by elevated pCO2 only in the first week after the cut; under high N fertilisation, elevated pCO2 increased the amount of mineral N that was apparently available to the plants. Elevated pCO2 did not affect apparent net transformation of N, loss of N or uptake of N by plants. The present data are consistent with earlier results and suggest that the amount of N available to plants from soil resources does not generally increase under elevated atmospheric pCO2. Thus, a possible limiting ef

Published
2018

16. Variation in acclimation of photosynthesis in Trifolium repens after eight years of exposure to Free Air CO2 Enrichment (FACE)

Author

Ainsworth, Elizabeth A., Rogers, Alistair, Blum, Herbert, Nösberger, Josef, Long, Stephen P., Ainsworth, Elizabeth A., Rogers, Alistair, Blum, Herbert, Nösberger, Josef, and Long, Stephen P.

Abstract

The initial stimulation of photosynthesis observed on elevation of [CO2] in grasslands has been predicted to be a transient phenomenon constrained by the loss of photosynthetic capacity due to other limitations, notably nutrients and sinks for carbohydrates. Legumes might be expected partially to escape these feedbacks through symbiotic N2 fixation. The Free‐Air Carbon dioxide Enrichment (FACE) experiment at Eschikon, Switzerland, has been the longest running investigation of the effects of open‐air elevation of [CO2] on vegetation. The prediction of a long‐term loss of photosynthetic capacity was tested by analysing photosynthesis in Trifolium repens L. (cv. Milkanova) in the spring and autumn of the eighth, ninth and tenth years of treatment. A high and low N treatment also allowed a test of the significance of exogenous N‐supply in maintaining a stimulation of photosynthetic capacity in the long‐term. Prior work in this Free Air CO2 Enrichment (FACE) experiment has revealed that elevated [CO2] increased both vegetative and reproductive growth of T. repens independent of N treatment. It is shown here that the photosynthetic response of T. repens was also independent of N fertilization under both current ambient and elevated (600 µmol mol-1) [CO2]. There was a strong effect of season on photosynthesis, with light‐saturated rates (Asat) 37% higher in spring than in autumn. Higher Asat in the spring was supported by higher maximum Rubisco carboxylation rates (Vc,max) and maximum rates of electron transport (Jmax) contributing to RuBP regeneration. Elevated [CO2] increased Asat by 37% when averaged across all measurement periods and both N fertilization levels, and decreased stomatal conductance by 25%. In spring, there was no effect of elevated [CO2] on photosynthetic capacity of leaves, but in autumn both Vc,max and Jmax were reduced by approximately 20% in elevated [CO2]. The results show that acclimation of photosynthetic capacity can occur in a nitrogen‐fixing sp

Published
2017

17. Nitrogen rhizodeposition assessed by a (NH3)-N-15 shoot pulse-labelling of Lolium perenne L. grown on soil exposed to 9 years of CO2 enrichment

Author

Bazot, Stéphane, Blum, Herbert, Robin, Christophe, Laboratoire Agronomie et Environnement (LAE), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), and Institute of Plant Sciences

Subjects
ELEVATED ATMOSPHERIC CO2, RAY GRASS ANGLAIS, N-RHIZODEPOSITION, N FERTILISATION, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, 15N PULSE-LABELLING
Abstract

International audience; The effects of elevated CO2 concentration upon rhizodeposition of nitrogen were investigated on field-grown Lolium perenne planted in soil cores set into the resident soil of a intensively managed ryegrass sward treated with elevated CO2 for nine consecutive years, under two contrasted N fertilisation regimes (Swiss FACE Experiment). The planted cores were excavated from the ambiant (35 Pa pCO2) and enriched (60 Pa pCO2) rings at two dates during the growing season (spring and early autumn). The cores were brought back to the laboratory for a pulse-labelling of ryegrass shoots with 15NH3, in order to quantify 15N-rhizodeposition. A recovery of 10–16% of the total 15N administred to the plant was recovered in the plant–soil system 48 h after the pulse-labelling; significant amounts of 15N were released into the soil adhering (adhering soil: AS) to the roots (0.44 μg 15N g AS−1 and 0.60 μg g AS−1 in the spring and the autumn samplings, respectively). In the spring sampling, there was no effect of atmospheric CO2 concentration on N rhizodeposition. In the autumn sampling, elevated CO2 stimulated N rhizodeposition that amounted to 7.2 and 5.2 mg 15N m−2, under elevated and ambient CO2, respectively. Nitrogen rhizodeposition was higher at high N (56 gN m−2) than at low N fertilisation (14 gN m−2), whatever the sampling date investigated. The mechanisms by which elevated atmospheric CO2 leads to a stimulation of the net root-released N flux remains to be investigated: was it caused by a higher nitrogen immobilisation by the microbial biomass and a reduced re-assimilation of mineralized N and/or by a stimulation of N efflux from roots? Concomitant to the observed reduction of C rhizodeposition, the stimulation of net N efflux suggests that the quality of root released compounds was modified under elevated CO2 concentration.

Published
2008
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45. FACE Value: Perspectives on the Future of Free-Air CO2 Enrichment Studies.

Author

Caldwell, M. M., Heldmaier, G., Jackson, R. B., Lange, O. L., Mooney, H. A., Schulze, E. -D., Sommer, U., Nösberger, Josef, Long, Stephen P., Norby, Richard J., Stitt, Mark, Hendrey, George R., Blum, Herbert, Rogers, A., Ainsworth, E. A., and Kammann, C.

Abstract

Free-air CO2 enrichment studies have been a valuable tool for the investigation of plant and ecosystem responses to rising CO2 levels. The challenges for the next phase of FACE research are clear. Multidisciplinary teams of investigators must take advantage of emerging technologies to significantly increase our mechanistic understanding of the responses that FACE experiments have confirmed will take place during the next century.If we seek the ability to predict and understand how our managed, and natural, ecosystems will respond to the predicted multiple and concurrent changes in our environment, more interactions with other global change factors must be included in future experiments. To meet these challenges, future FACE experiments will need to be larger to accommodate multiple environmental changes. [ABSTRACT FROM AUTHOR]

Published
2006
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46. Increases in Atmospheric [CO2] and the Soil Food Web.

Author

Caldwell, M. M., Heldmaier, G., Jackson, R. B., Lange, O. L., Mooney, H. A., Schulze, E. -D., Sommer, U., Nösberger, Josef, Long, Stephen P., Norby, Richard J., Stitt, Mark, Hendrey, George R., Blum, Herbert, Phillips, D. A., Fox, T. C., Ferris, H., and Moore, J. C.

Abstract

Organic inputs to soil are comprised largely of plant debris and root exudation, which is responsible for rhizodeposition. Increases in organic matter inputs from plants growing under elevated [CO2] affect soil microorganisms and a limited set of conclusions can be drawn. Bacterial and fungal communities in soil ecosystems use such plant materials as resources to support multiple levels of tiny grazers and predators, which comprise soil food webs.Ten years of elevated [CO2] at the ETH FACE site produced data on soil protozoa and nematodes that are consistent with adjustments predicted for availability of soil bacteria and fungi.Disparate changes in soil microorganisms and complex adjustments in food web structure reported under higher [CO2] in a multitude of other experiments suggest that a better understanding of C resource availability is needed.Increases in living root mass under elevated [CO2] could affect soil food webs through additional exudation, but limited information is available on changes in root exudation under such conditions. We summarize here a new, more complex, understanding of root exudation that includes mechanisms by which microorganisms, and possibly their predators within the food web, can actively enhance root exudation. Initial experiments indicate that higher [CO2] can increase root exudation of amino acids under axenic conditions by two separate mechanisms and these could result in more rhizodeposition.Little is known about how elevated [CO2] levels alter predation, another key connection between the soil food web and the plant, but reductionist studies are beginning to support the concept that specific molecules affect predation and influence many organismic interactions in the root zone.Because the fossil record suggests soil food webs were exposed to widely varied levels of [CO2] for long periods, a certain stability of these interactions should be expected as global atmospheric [CO2] increases. [ABSTRACT FROM AUTHOR]

Published
2006
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50. Effects of Elevated [CO2] and N Fertilization on Interspecific Interactions in Temperate Grassland Model Ecosystems.

Author

Caldwell, M. M., Heldmaier, G., Jackson, R. B., Lange, O. L., Mooney, H. A., Schulze, E. -D., Sommer, U., Nösberger, Josef, Long, Stephen P., Norby, Richard J., Stitt, Mark, Hendrey, George R., Blum, Herbert, Lüscher, A., and Aeschlimann, U.

Abstract

Elevated [CO2] and N fertilization influenced markedly yield, species proportion and interspecific interactions in temperate grassland. These changes may significantly affect amount and quality of forage and ecosystem functioning. Interspecific differences in the response to e[CO2] were stronger in the mixed sward (−2 % for L. perenne and +65 % for T. repens) than in the pure swards (+13 % for L. perenne and +19 % for T. repens), demonstrating that e[CO2] does affect not only the yield, but also the interspecific interactions and the species composition of mixed plant communities. Thus, studying the ecosystem response to e[CO2] needs experiments with mixed plant communities.RY and RNY <0.5 for T. repens provides evidence that T. repens was adversely affected from competition with the grass, while the grass competed more successfully for resources (RY >0.5) or even clearly gained from synergistic effects (RY >1.0).The extreme resource complementarity (RNYT of up to 1.9) at low N and the loss of resource complementarity (RYT and RNYT close to 1.0) at high N demonstrate that mineral N availability was the most important limiting factor for plant growth and interspecific interactions in the low N treatment of the Swiss FACE experiment. Thus, this FACE experiment with grasses and legumes provides a good tool to study effects of e[CO2] on the N cycle of grassland ecosystems under strongly limiting and non-limiting N availability. [ABSTRACT FROM AUTHOR]

Published
2006
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