Effects of elevated CO₂, warming and drought episodes on plant carbon uptake in a temperate heath ecosystem are controlled by soil water status

• Published in: Plant, cell and environment Vol. 34; no. 7; pp. 1207 - 1222
• Main Authors: ALBERT, K.R, RO-POULSEN, H, MIKKELSEN, T.N, MICHELSEN, A, VAN DER LINDEN, L, BEIER, C
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2011
• Subjects: Acclimatization; Calluna - metabolism; Calluna - physiology; Calluna vulgaris; carbon; Carbon - metabolism; Carbon dioxide; Carbon Dioxide - metabolism; Carbon Isotopes - analysis; CLIMAITE; Climate Change; Down-Regulation; Drought; Droughts; Ecosystem; ecosystems; FACE; Growing season; Heaths; Hot Temperature; leaves; Light; multifactor experiment; Nitrogen - metabolism; Photosynthesis; photosynthetic capacity; Plant Leaves - metabolism; Plant Leaves - physiology; Plant Shoots - physiology; Plant Stomata - physiology; Shrubs; Soil; Soil - chemistry; Soil moisture; soil water; stomatal conductance; summer; Water - metabolism; water saving
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2011.02320.x

The impact of elevated CO₂, periodic drought and warming on photosynthesis and leaf characteristics of the evergreen dwarf shrub Calluna vulgaris in a temperate heath ecosystem was investigated. Photosynthesis was reduced by drought in midsummer and increased by elevated CO₂ throughout the growing season, whereas warming only stimulated photosynthesis early in the year. At the beginning and end of the growing season, a T × CO₂ interaction synergistically stimulated plant carbon uptake in the combination of warming and elevated CO₂. At peak drought, the D × CO₂ interaction antagonistically down-regulated photosynthesis, suggesting a limited ability of elevated CO₂ to counteract the negative effect of drought. The response of photosynthesis in the full factorial combination (TDCO₂) could be explained by the main effect of experimental treatments (T, D, CO₂) and the two-factor interactions (D × CO₂, T × CO₂). The interactive responses in the experimental treatments including elevated CO₂ seemed to be linked to the realized range of treatment variability, for example with negative effects following experimental drought or positive effects following the relatively higher impact of night-time warming during cold periods early and late in the year. Longer-term experiments are needed to evaluate whether photosynthetic down-regulation will dampen the stimulation of photosynthesis under prolonged exposure to elevated CO₂.