Oecologia

, Volume 127, Issue 4, pp 540–548

A link between plant diversity, elevated CO2 and soil nitrate

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DOI: 10.1007/s004420000612

Cite this article as:
, , et al. Oecologia (2001) 127: 540. doi:10.1007/s004420000612

Abstract.

Interactive effects of reductions in plant species diversity and increases in atmospheric CO2 were investigated in a long-term study in nutrient-poor calcareous grassland. Throughout the experiment, soil nitrate was persistently increased at low plant species diversity, and CO2 enrichment reduced soil [NO3] at all levels of plant species diversity. In our study, soil [NO3] was unrelated to root length density, microbial biomass N, community legume contents, and experimental plant communities differed only little in total N pools. However, potential nitrification revealed exactly the same treatment effects as soil [NO3], providing circumstantial evidence that nitrification rates drove the observed changes in [NO3]. One possible explanation for plant diversity effects on nitrification lies in spatial and temporal interspecific differences in plant N uptake, which would more often allow accumulation of NH4+ in part of the soil profile at low diversity than in more species-rich plant communities. Consequently, nitrification rates and soil [NO3] would increase. Elevated CO2 increased soil water contents, which may have improved NO3 diffusion to the root surface thereby reducing soil [NO3]. Higher soil moisture at elevated CO2 might also reduce nitrification rates due to less aerobic conditions. The accordance of the diversity effect on soil [NO3] with previous experiments suggests that increased soil [NO3] at low species diversity is a fairly general phenomenon, although the mechanisms causing high [NO3] may vary. In contrast, experimental evidence for effects of CO2 enrichment on soil [NO3] is ambiguous, and the antagonistic interaction of plant species reductions and elevated CO2 we have observed is thus probably less universal.

Ammonium Nitrification Nitrogen mineralization Perennial grassland Root length density

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

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  1. 1.Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland
  2. 2.University of Hohenheim, 70599 Stuttgart, Germany
  3. 3.Université Paris-Sud, Ecologie des Populations et Communautés, URA CNRS 2154, 91405 Orsay Cedex, France
  4. 4.Institut für Umweltwissenschaften, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
  5. 5.Federal Office and Research Centre for Agriculture, Spargelfeldstrasse 191, 1226 Vienna, Austria
  6. 6.Present address: Landcare Research, Private Bag 11 052, Palmerston North, New Zealand