Weed interference with field-grown soyabean decreases under elevated [CO 2] in a FACE experiment

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Rising atmospheric [CO 2] is predicted to affect C 3 and C 4 weed interference with crop species differently, with C 3 weeds benefiting more from elevated [CO 2] (eCO 2) than C 4 species. Our aim was to quantify impacts of eCO 2 on C 3 and C 4 weeds at three levels of biological organisation: individual, population and community. We conducted a field study in 2007 and 2008 within the SoyFACE experiment in Champaign, Illinois, USA, in which Amaranthus rudis (C 4) and Chenopodium album (C 3) were grown with soyabean. This is a Free Air CO 2 Enrichment (FACE) experiment. Elevated [CO 2] influenced weeds at all levels of biological organisation. However, community-level impacts were largest. Interference by A. rudis and C. album with soyabean was 37% and 11% lower, respectively, in eCO 2. In residual weed communities under ambient [CO 2] (aCO 2), C 3 and C 4 species were equally likely to dominate the community, whereas in eCO 2, there was a 90% chance of community dominance by C 3 species. Future investigations of weed ecology and global change under FACE conditions may improve their inference space by including sources of environmental stress such as ozone, heat and drought. 2012. This article is a US Government work and is in the public domain in the USA.

Original languageEnglish (US)
Pages (from-to)277-285
Number of pages9
JournalWeed Research
Issue number3
StatePublished - Jun 2012


  • Amaranthus rudis
  • C and C photosynthesis
  • Chenopodium album
  • Demography
  • Free Air CO Enrichment
  • Glycine max
  • Growth analysis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Agronomy and Crop Science
  • Plant Science


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