Marissink, Mark
- Department of Ecology and Crop Production Sciences, Swedish University of Agricultural Sciences
Plants have shown responses to elevated CO2 in many experiments under controlled conditions. Yet, predicting responses under field conditions is still difficult and the number of long-term field studies on elevated CO2 is limited. Here the results from 4 years' physiology and production studies in the field are presented. In a species-rich semi-natural grassland in central Sweden open-top chambers were used to study the effects of elevated carbon dioxide concentration (twice the ambient level) on plant production, physiology and species composition. The first three growing seasons showed a 30-60% increase in above-ground biomass at harvest under elevated CO2. During the fourth year there was no difference in above-ground biomass between the treatments. For all years, leaf-level photosynthesis for measured species was 30-60% higher and stomatal conductance 20-40% lower at elevated CO2 than at ambient. Nitrogen concentration in stems and leaves was 5-20% lower at elevated CO2. Specific leaf area (SLA) did not show any response to elevated CO2. The variation in the effect of CO2 on above-ground production was attributed to variation in water stress, with low water stress (high precipitation) giving the least effect. It is concluded that even in this relatively low-production system CO2 effects can persist for at least several years and even increase. (C) 2002 Elsevier Science B.V. All rights reserved.
elevated CO2; above-ground biomass; water-use efficiency; open-top chambers; photosynthesis; stomatal conductance; semi-natural grasslands
Agriculture, Ecosystems and Environment
2002, volume: 93, number: 1-3, article number: PII S0167-8809(01)00356-5
Ecology
https://res.slu.se/id/publ/127342