Effects of elevated CO{sub 2} on plant nitrogen uptake, microbial biomass and microbial activity: A field study in artificially established calcareous grassland communities of differing plant diversity
- Univ. of Basal (Switzerland); and others
Potential increases in rhizodeposition under elevated CO{sub 2} has been hypothesized to stimulate microbial activity and, therefore, alter plant nitrogen availability. We investigated nitrogen relations of a nutrient poor calcareous grassland. Plant communities with 5, 12 or 31 of the species locally present were established in field plots and exposed to ambient (356{mu}l l{sup -1}) or elevated (600{mu}l l{sup -1}) atmospheric CO{sub 2} using open-top chambers. After 5 months of CO{sub 2} exposure, soil microbial biomass, microbial activity, plant above- and belowground biomass and nitrogen contents were measured. No significant effect of elevated CO{sub 2} or plant species number on soil microbial biomass or activity was observed. Elevated CO{sub 2} led to significant increases in aboveground plant biomass in the 31 spp. community only. Under elevated CO{sub 2}, net ecosystem CO{sub 2} gas exchange and fine root biomass increased in all communities. Whole plot plant nitrogen uptake did not change, but significant increases in C:N ratios of N rich forbs were found. We conclude that, although rhizodeposition appears to have increased under elevated CO{sub 2}, neither microbial biomass nor activity changed significantly. Finally, the increased amount of fine roots observed under elevated CO{sub 2} led to intensified root exploration of soil, but did not result in increased total plant nitrogen uptake.
- OSTI ID:
- 95855
- Report Number(s):
- CONF-9507129--
- Journal Information:
- Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 2 Vol. 76; ISSN BECLAG; ISSN 0012-9623
- Country of Publication:
- United States
- Language:
- English
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