Abiotic drivers and their interactive effect on the flux and carbon isotope (14C and δ13C) composition of peat-respired CO2

• Published in: Soil biology & biochemistry Vol. 43; no. 12; pp. 2432 - 2440
• Main Authors: Hardie, S.M.L., Garnett, M.H., Fallick, A.E., Rowland, A.P., Ostle, N.J., Flowers, T.H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.12.2011
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; British Isles, England; Temperature; C; Carbon isotope discrimination; Carbon dioxide; Carbon Isotopes; Environmental factor; Abiotic factor; Q; Humidity; Soil science; Radiolabelling; Moisture; CO; Peat; Dynamical climatology; Carbon cycle; Substrate; Climate change; 1; C-14; C-13; δ; Carbon cycling; Respiration; Substrate quality
• ISSN: 0038-0717
• DOI: 10.1016/j.soilbio.2011.08.010

Feedbacks to global warming may cause terrestrial ecosystems to add to anthropogenic CO2 emissions, thus exacerbating climate change. The contribution that soil respiration makes to these terrestrial emissions, particularly from carbon-rich soils such as peatlands, is of significant importance and its response to changing climatic conditions is of considerable debate. We collected intact soil cores from an upland blanket bog situated within the northern Pennines, England, UK and investigated the individual and interactive effects of three primary controls on soil organic matter decomposition: (i) temperature (5, 10 and 15 degree C); (ii) moisture (50 and 100% field capacity - FC); and (iii) substrate quality, using increasing depth from the surface (0-10, 10-20 and 20-30 cm) as an analogue for increased recalcitrance of soil organic material. Statistical analysis of the results showed that temperature, moisture and substrate quality all significantly affected rates of peat decomposition. Q10 values indicated that the temperature sensitivity of older/more recalcitrant soil organic matter significantly increased (relative to more labile peat) under reduced soil moisture (50% FC) conditions, but not under 100% FC, suggesting that soil microorganisms decomposing the more recalcitrant soil material preferred more aerated conditions. Radiocarbon analyses revealed that soil decomposers were able to respire older, more recalcitrant soil organic matter and that the source of the material (deduced from the delta 13C analyses) subject to decomposition, changed depending on depth in the peat profile.