title: The response of plants to elevated CO2: II. Competitive interactions among annual plants under varying light and nutrients.
abstract: Communities, consisting of six co-occurring, disturbed site annuals, were subjected to CO2unenriched (300 ppm) and to CO2enriched (450 and 600 ppm) atmospheres at different levels of light and nutrient availability. In general, total community production increased with CO2enrichment to 450 ppm, but a further increase in CO2to 600 ppm had little or no effect. The response of community production to CO2level was not affected by nutrient availability but was affected by light level.Of the six species, four display C3metabolism. The proportion of total community production contributed by these species increased as a result of CO2enrichment, and was dependent upon both light and nutrient availability. The relative success of some species, particularly in terms of reproduction (total seed biomass), was significantly altered by CO2concentration depending on the level of nutrients. There were not only changes in reproductive success (seed biomass) and shoot biomass but also changes in the proportion of biomass allocated to seed.These experiments demonstrate that CO2enrichment does affect annual plant communities both in terms of productivity and species composition and that the affect of CO2on such system may depend upon other resources such as light and nutrients.
authors.affiliation: Department of Plant Biology, University of Illinois, 61801, Urbana, IL, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Zangerl
authors.affiliation: Department of Plant Biology, University of Illinois, 61801, Urbana, IL, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Bazzaz