Effects of elevated atmospheric CO₂, prolonged summer drought and temperature increase on N₂O and CH₄ fluxes in a temperate heathland

• Published in: Soil biology & biochemistry Vol. 43; no. 8; pp. 1660 - 1670
• Main Authors: Carter, Mette S, Ambus, Per, Albert, Kristian R, Larsen, Klaus S, Andersson, Michael, Priemé, Anders, van der Linden, Leon, Beier, Claus
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.08.2011; Elsevier
• Subjects: Agronomy. Soil science and plant productions; atmosphere; Biochemistry and biology; Biological and medical sciences; carbon dioxide; Chemical, physicochemical, biochemical and biological properties; climate change; drought; ecosystems; emissions; Fundamental and applied biological sciences. Psychology; greenhouse gases; heathlands; methane; methane production; nitrogen; nitrous oxide; Physics, chemistry, biochemistry and biology of agricultural and forest soils; rhizodeposition; soil; Soil science; summer; temperate zones; temperature; winter; Methane; Warming; Heathland and moor; Carbon dioxide; Summer; Increase; Sandy soil; Dynamical climatology; Climate change; CLIMAITE; Atmosphere; Ecosystem; Greenhouse gas; Ecosystem manipulation; Soil science; Nitrous oxide; Shrubland; Rewetting; Treatment interaction; Nitrogen protoxide; Drought; Shrubbery
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2011.04.003

In temperate regions, climate change is predicted to increase annual mean temperature and intensify the duration and frequency of summer droughts, which together with elevated atmospheric carbon dioxide (CO₂) concentrations, may affect the exchange of nitrous oxide (N₂O) and methane (CH₄) between terrestrial ecosystems and the atmosphere. We report results from the CLIMAITE experiment, where the effects of these three climate change parameters were investigated solely and in all combinations in a temperate heathland. Field measurements of N₂O and CH₄ fluxes took place 1–2 years after the climate change manipulations were initiated. The soil was generally a net sink for atmospheric CH₄. Elevated temperature (T) increased the CH₄ uptake by on average 10 μg C m⁻² h⁻¹, corresponding to a rise in the uptake rate of about 20%. However, during winter elevated CO₂ (CO₂) reduced the CH₄ uptake, which outweighed the positive effect of warming when analyzed across the study period. Emissions of N₂O were generally low (<10 μg N m⁻² h⁻¹). As single experimental factors, elevated CO₂, temperature and summer drought (D) had no major effect on the N₂O fluxes, but the combination of CO₂ and warming (TCO₂) stimulated N₂O emission, whereas the N₂O emission ceased when CO₂ was combined with drought (DCO₂). We suggest that these N₂O responses are related to increased rhizodeposition under elevated CO₂ combined with increased and reduced nitrogen turnover rates caused by warming and drought, respectively. The N₂O flux in the multifactor treatment TDCO₂ was not different from the ambient control treatment. Overall, our study suggests that in the future, CH₄ uptake may increase slightly, while N₂O emission will remain unchanged in temperate ecosystems on well-aerated soils. However, we propose that continued exposure to altered climate could potentially change the greenhouse gas flux pattern in the investigated heathland.