EFFECTS OF ELEVATED CO2 ON AN ARTIFICIAL GRASSLAND COMMUNITY - COMPETITION, INVASION AND NEIGHBORHOOD GROWTH

1. We analysed the effect of CO2 enrichment on plant-plant interaction s in an artificial community dominated by Trifolium repens and Poa pra tensis. Plants were enriched either in open-tops or growth chambers. 2 . Our main hypotheses were supported, i.e. elevated CO2 increased the strength and number of plant-plant interactions and Trifolium benefite d more than Poa from a high CO2 concentration. However, responses diff ered depending on whether plants were enriched in open-top or in growt h chambers. These differences are discussed regarding possible density dependence. 3. This study emphasizes the importance of invasions in t he dynamics of our artificial community. Invasiveness was best predict ed by traits pertaining to space acquisition. 4. To provide insights i nto evolutionary processes, phenotypic plasticity and genetic correlat ion of individual traits were analysed across environments. Our result s suggest that little opportunity had occurred for adaptive plasticity to evolve for most characters.