Long-term effects of ozone on CO sub(2) exchange in peatland microcosms

• Published in: Atmospheric environment (1994) Vol. 45; no. 24; pp. 4002 - 4007
• Main Authors: Haapala, Jaana K, Morsky, Sami K, Rinnan, Riikka, Saarnio, Sanna, Martikanen, Pertti J, Holopainen, Toini, Silvola, Jouko
• Format: Journal Article
• Language: English
• Published: 01.08.2011
• Subjects: Carbon dioxide; Density; Eriophorum vaginatum; Leaves; Ozone; Peatlands; Photochemical; Photosynthesis; Respiration
• ISSN: 1352-2310
• DOI: 10.1016/j.atmosenv.2011.04.057

Effects of elevated tropospheric ozone concentration on the CO sub(2) exchange of peatland microcosms and the photosynthetic capacity of the dominating sedge, Eriophorum vaginatum, were studied in a four-year open-field experiment. The net ecosystem CO sub(2) exchange and the dark respiration rate of the microcosms were measured with the closed chamber method. The CO sub(2) assimilation rate and chlorophyll fluorescence (maximal photochemical efficiency of PSII, Fv/Fm) of E. vaginatum leaves were also measured. The gross photosynthesis rate of the microcosms was transiently decreased by ozone exposure during the first year. During the fourth year, the gross photosynthesis and dark respiration rate were both slightly increased by ozone exposure but this was due to the increased density of sedge leaves and no difference was found in Fv/Fm. In overall, chronic ozone exposure had only slight effect on the CO sub(2) exchange of the peatland microcosms.