title: Seasonal acclimation of the moss Polytrichum juniperinum Hedw. to natural and enhanced ultraviolet radiation.
abstract: Short- and long-term changes in the methanol-extractable UV-absorbing compounds and biomass of the pioneer moss Polytrichum juniperinum in response to natural and enhanced UV radiation were studied. Under natural conditions, the compounds were found to fluctuate seasonally. In summer these compounds correlated negatively with irradiation. The concentration was low in July after a period of simultaneous heat, drought and high irradiation. Transient positive correlation between daily concentration and UV was seen in June. The concentration increased towards autumn and was relatively high under snow. Two enhanced UV experiments were performed. Seasonality in the compounds was again observed, with negative correlations with irradiation. During the first weeks, a transient inhibition of compound production was observed after the daily UV-B treatment. After six years of modulated UV-treatment in situ, photosynthesizing biomass decreased under UV-B and increased under UV-A. A larger variation in the UV-absorbing compounds was observed under UV-B treatment.
authors.affiliation: University of Oulu, Department of Biology, P.O. Box 3000, FIN-90014 University of Oulu, Finland. niina.lappalainen@oulu.fi
authors.forename: Niina M
authors.initials: NM
authors.lastname: Lappalainen
authors.forename: Satu
authors.initials: S
authors.lastname: Huttunen
authors.forename: Hanne
authors.initials: H
authors.lastname: Suokanerva
authors.forename: Kaisa
authors.initials: K
authors.lastname: Lakkala
mesh_terms: D018533:Biomass; D044002:Bryophyta / Q000737:chemistry / Q000502:physiology* / Q000528:radiation effects*; D010788:Photosynthesis / Q000528:radiation effects; D010936:Plant Extracts / Q000032:analysis; D012621:Seasons; D014466:Ultraviolet Rays
chemical_list: D010936:Plant Extracts