The ongoing climate change affects biogeochemical cycling in terrestrial ecosystems, but the magnitude and direction of this impact is yet unclear. To shed further light on the climate change impact, we investigated alterations in the soil nitrogen (N) cycling in a Danish heathland after 5 years of exposure to three climate change factors, i.e. warming, elevated CO2 (eCO(2)) and summer drought, applied both in isolation and in combination. By conducting laboratory N-15 tracing experiments we show that warming increased both gross N mineralization and nitrification rates. In contrast, gross nitrification was decreased by eCO(2), an effect that was more pronounced when eCO(2) was combined with warming and drought. Moreover, there was an interactive effect between the warming and CO2 treatment, especially for N mineralization: rates increased at warming alone but decreased at warming combined with eCO(2). In the full treatment combination, simulating the predicted climate for the year 2075, gross N transformations were only moderately affected compared to control, suggesting a minor alteration of the N cycle due to climate change. Overall, our study confirms the importance of multifactorial field experiments for a better understanding of N cycling in a changing climate, which is a prerequisite for more reliable model predictions of ecosystems responses to climate change.
Biogeochemistry, 2014, Vol 120, Issue 1-3, p. 191-201
climate change; terrestrial ecosystem; carbon dioxide 124-38-9; soil nitrogen signaling; 07502, Ecology: environmental biology - General and methods; 07504, Ecology: environmental biology - Bioclimatology and biometeorology; 10060, Biochemistry studies - General; Ecology, Environmental Sciences; Environmental Sciences; nitrogen-15 tracing experiment applied and field techniques; predictive model mathematical and computer techniques; stable isotope method applied and field techniques; Biochemistry and Molecular Biophysics; Climatology; Methods and Techniques; Terrestrial Ecology; ENVIRONMENTAL; GEOSCIENCES,; ATMOSPHERIC CARBON-DIOXIDE; ELEVATED CO2; SUMMER DROUGHT; TERRESTRIAL ECOSYSTEMS; TEMPERATE HEATHLAND; PROCESS RESPONSES; GRASSLAND SOIL; N DYNAMICS; N-15; MODELS; N-15 tracing; Climate change; Elevated CO2; Warming; Summer drought; Nitrogen cycle; CLIMATIC changes; HASH(0x4511490); 15N tracing