Symbiotic Nitrogen Fixation: One Key to Understand the Response of Temperate Grassland Ecosystems to Elevated CO2?

Hartwig, Ueli A.; Zanetti, S.; Hebeisen, Thomas; Lúscher, A.; Frehner, Monika; Fischer, Bernt; Kessel, Chris van; Hendrey, George R.; Blum, Hermann; Nösberger, J.

doi:10.1016/b978-012420870-4/50048-7

Cited by 37 publications

(31 citation statements)

References 51 publications

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“…Our results are consistent with the hypothesis that the amount of N, that is fixed, which is inversely related to the N content of an ecosystem (Granhall, 1981), increases under elevated pC0, as a result of the increased C:N ratio in the ecosystem (Gifford, 1992;Hartwig et al, 1996;Soussana and Hartwig, 1996). Indeed, under elevated pC0, the mixtures introduced more symbiotically fixed N (+7.…”

Section: N Fixation?supporting

confidence: 91%

“…If so, legumes, Symbiotic N, fix,ation is considered to be the major process causing the introduction of N into most terrestrial ecosystems. It can be assumed that the sequestration of C and N into an ecosystem occur in concert (Granhall, 1981;Gifford, 1992;Hartwig et al, 1996), so symbiotic N, fixation may not be regulated only by the N demand of the individual plant, but also indirectly by the N demand of the ecosystem as a whole . Numerous studies covering a wide range of N,-fixing legumes and woody species have demonstrated an increase in total nitrogenase activity per plant under elevated pC0, (Hardy and Havelka, 1976;Phillips et al, 1976;Masterson and Sherwood, 1978;Finn and Brun, 1982;Williams et al, 1982;Murphy, 1986;Norby, 1987;Arnone and Gordon, 1990).…”

mentioning

confidence: 99%

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Stimulation of Symbiotic N2 Fixation in Trifolium repens L. under Elevated Atmospheric pCO2 in a Grassland Ecosystem

et al. 1996

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~Symbiotic N, fixation is one of the main processes that introduces N into terrestrial ecosystems. As such, it may be crucial for the sequestration of the extra C available in a world of continuously increasing atmospheric CO, partial pressure (pC0,). The effect of elevated pC0, (60 Pa) on symbiotic N, fixation ('5N-isotope dilution method) was investigated using Free-Air-C0,-Enrichment technology over a period of 3 years. Trifolium repens was cultivated either alone or together with Lolium perenne (a nonfixing reference crop) in mixed swards. Two different N fertilization levels and defoliation frequencies were applied. The total N yield increased consistently and the percentage of plant N derived from symbiotic N, fixation increased significantly in T. repens under elevated pC0,. All additionally assimilated N was derived from symbiotic N, fixation, not from the soil. In the mixtures exposed to elevated pCO,, an increased amount of symbiotically fixed N (+7.8,8.2, and 6.2 g m-' a-' in 1993, 1994, and 1995, respectively) was introduced into the system. lncreased N, fixation is a competitive advantage for T. repens in mixed swards with pasture grasses and may be a crucial factor in maintaining the C:N ratio in the ecosystem as a whole.

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Section: N Fixation?supporting

confidence: 91%

mentioning

confidence: 99%

Stimulation of Symbiotic N2 Fixation in Trifolium repens L. under Elevated Atmospheric pCO2 in a Grassland Ecosystem

et al. 1996

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“…From the perspective of microbial numbers, Zak et al [70] suggested that an increased carbon input into the soil could be counterbalanced by an increased C:N ratio, leading to unchanged microbial numbers. It is likely that in a grass monoculture under elevated CO 2 the availability of soil mineral nitrogen decreases because of the increased C:N ratio of plant-derived organic matter introduced into the soil [24]. Diaz et al [17] showed a nutritional limitation of plant growth due to CO 2 -induced mineral nutrient sequestration by expanding microbiota.…”

Section: Impact Of Elevated Co 2 On Soil Heterotrophic Bacteriamentioning

confidence: 99%

“…This is supported by the CO 2 -induced increased symbiotic nitrogen fixation [59,72,74] and proportion of T. repens in mixed cultures [23][24][25]. In grassland ecosystems, leguminous plants play a key role in the response to elevated CO 2 .…”

Section: Impact Of Elevated Co 2 On the Microbial Community Structurementioning

confidence: 99%

Influence of an Elevated Atmospheric CO 2 Content on Soil and Rhizosphere Bacterial Communities Beneath Lolium perenne and Trifolium repens under Field Conditions

1999

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The increase in atmospheric CO 2 content alters C 3 plant photosynthetic rate, leading to changes in rhizodeposition and other root activities. This may influence the activity, the biomass, and the structure of soil and rhizosphere microbial communities and therefore the nutrient cycling rates and the plant growth. The present paper focuses on bacterial numbers and on community structure. The rhizospheres of two grassland plants, Lolium perenne (ryegrass) and Trifolium repens (white clover), were divided into three fractions: the bulk soil, the rhizospheric soil, and the rhizoplaneendorhizosphere. The elevated atmospheric CO 2 content increased the most probable numbers of heterotrophic bacteria in the rhizosphere of L. perenne. However, this effect lasted only at the beginning of the vegetation period for T. repens. Community structure was assessed after isolation of DNA, PCR amplification, and construction of cloned 16S rDNA libraries. Amplified ribosomal DNA restriction analysis (ARDRA) and colony hybridization with an oligonucleotide probe designed to detect Pseudomonas spp. showed under elevated atmospheric CO 2 content an increased dominance of pseudomonads in the rhizosphere of L. perenne and a decreased dominance in the rhizosphere of T. repens. This work provides evidence for a CO 2 -induced alteration in the structure of the rhizosphere bacterial populations, suggesting a possible alteration of the plant-growthpromoting-rhizobacterial (PGPR) effect.

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“…This results in a decreased soil N availability (Hartwig et al 1996), due to higher sequestration by the plant and, depending on the conditions, a decreased bacterial biomass (Hu et al 2001). Then, the slow-growing K-strategists, more adapted to degrade less labile substrates, are hampered and these substrates accumulate, increasing the soil organic matter content.…”

Section: Responses Of Microbial Biomass Cell Number and Activitymentioning

confidence: 97%

The Influence of Elevated [CO2] on Diversity, Activity and Biogeochemical Functions of Rhizosphere and Soil Bacterial Communities

Tarnawski

Aragno

Managed Ecosystems and CO2

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Symbiotic Nitrogen Fixation: One Key to Understand the Response of Temperate Grassland Ecosystems to Elevated CO2?

Cited by 37 publications

References 51 publications

Stimulation of Symbiotic N2 Fixation in Trifolium repens L. under Elevated Atmospheric pCO2 in a Grassland Ecosystem

Stimulation of Symbiotic N2 Fixation in Trifolium repens L. under Elevated Atmospheric pCO2 in a Grassland Ecosystem

Influence of an Elevated Atmospheric CO 2 Content on Soil and Rhizosphere Bacterial Communities Beneath Lolium perenne and Trifolium repens under Field Conditions

The Influence of Elevated [CO2] on Diversity, Activity and Biogeochemical Functions of Rhizosphere and Soil Bacterial Communities

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