High Resilience in Heathland Plants to Changes in Temperature, Drought, and CO₂ in Combination: Results from the CLIMAITE Experiment

Climate change scenarios predict simultaneouslyincrease in temperature, altered precipitation patternsand elevated atmospheric CO₂ concentration,which will affect key ecosystem processes and plantgrowth and species interactions. In a large-scaleexperiment, we investigated the effects of in situexposure to elevated atmospheric CO₂ concentration,increased temperature and prolonged droughtperiods on the plant biomass in a dry heathland(Brandbjerg, Denmark). Results after 3 yearsshowed that drought reduced the growth of thetwo dominant species Deschampsia flexuosa and Callunavulgaris. However, both species recoveredquickly after rewetting and the drought had nosignificant effect on annual aboveground biomassproduction. We did not observe any effects of increasedtemperature. Elevated CO₂ stimulated the biomass production for D. flexuosa in one out ofthree years but did not influence the standingbiomass for either D. flexuosa or the ecosystem asmore litter was produced. Treatment combinationsshowed little interactions on the measuredparameters and in particular elevated CO₂ did notcounterbalance the drought effect on plant growth,as we had anticipated. The plant community didnot show any significant responses to the imposedclimate changes and we conclude that the twoheathland species, on a short time scale, will berelatively resistant to the changes in climatic conditions