title: Seasonal and inter-annual variation in the chlorophyll content of three co-existing Sphagnum species exceeds the effect of solar UV reduction in a subarctic peatland.
abstract: We measured chlorophyll (chl) concentration and chl a/b ratio in Sphagnum balticum, S. jensenii, and S. lindbergii, sampled after 7 and 8 years of ultraviolet-B (UVB) and temperature manipulation in an open field experiment in Finnish Lapland (68°N). We used plastic filters with different transmittance of UVB radiation to manipulate the environmental conditions. The plants were exposed to (1) attenuated UVB and increased temperature, (2) ambient UVB and increased temperature and (3) ambient conditions. Chlorophyll was extracted from the capitula of the mosses and the content and a/b ratio were measured spectrophotometrically. Seasonal variation of chlorophyll concentration in the mosses was species specific. Temperature increase to 0.5-1 °C and/or attenuation of solar UVB radiation to ca. one fifth of the ambient (on average 12 vs. 59 uW/cm(2)) had little effect on the chlorophyll concentration or its seasonal variation. In the dominant S. lindbergii, UVB attenuation under increased temperature led to a transient decrease in chlorophyll concentration. Altogether, species-specific patterns of seasonal chlorophyll variation in the studied Sphagna were more pronounced than temperature and UVB treatment effects.
authors.affiliation: Department of Biology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland.
authors.forename: Anna
authors.initials: A
authors.lastname: Hyyryläinen
authors.affiliation: The Natural Resources Institute Finland, P.O. Box 16, 96300 Rovaniemi, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Rautio
authors.affiliation: Arctic Centre, University of Lapland, P.O. Box 122, 96101 Rovaniemi, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Turunen
authors.affiliation: Department of Biology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland.
authors.forename: Satu
authors.initials: S
authors.lastname: Huttunen
keywords: Chlorophyll; Peatlands; Sphagnum balticum; Sphagnum jensenii; Sphagnum lindbergii; UVB