title: Photosynthetic traits of Sphagnum and feather moss species in undrained, drained and rewetted boreal spruce swamp forests.
abstract: In restored peatlands, recovery of carbon assimilation by peat-forming plants is a prerequisite for the recovery of ecosystem functioning. Restoration by rewetting may affect moss photosynthesis and respiration directly and/or through species successional turnover. To quantify the importance of the direct effects and the effects mediated by species change in boreal spruce swamp forests, we used a dual approach: (i) we measured successional changes in moss communities at 36 sites (nine undrained, nine drained, 18 rewetted) and (ii) photosynthetic properties of the dominant Sphagnum and feather mosses at nine of these sites (three undrained, three drained, three rewetted). Drainage and rewetting affected moss carbon assimilation mainly through species successional turnover. The species differed along a light-adaptation gradient, which separated shade-adapted feather mosses from Sphagnum mosses and Sphagnum girgensohnii from other Sphagna, and a productivity and moisture gradient, which separated Sphagnum riparium and Sphagnum girgensohnii from the less productive S. angustifolium, S. magellanicum and S. russowii. Undrained and drained sites harbored conservative, low-production species: hummock-Sphagna and feather mosses, respectively. Ditch creation and rewetting produced niches for species with opportunistic strategies and high carbon assimilation. The direct effects also caused higher photosynthetic productivity in ditches and in rewetted sites than in undrained and drained main sites.
authors.affiliation: Peatland Ecology Group, Department of Forest Sciences, University of Helsinki P. O. Box 27, Helsinki, FI-00014, Finland ; School of Forest Resources and Environmental Science, Michigan Technological University 1400 Townsend Drive, Houghton, Michigan, 49931.
authors.forename: Laura
authors.initials: L
authors.lastname: Kangas
authors.affiliation: Peatland Ecology Group, Department of Forest Sciences, University of Helsinki P. O. Box 27, Helsinki, FI-00014, Finland.
authors.forename: Liisa
authors.initials: L
authors.lastname: Maanavilja
authors.affiliation: Institute of Botany, Academy of Sciences of the Czech Republic Dukelská 135, Třeboň, 379 82, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Hájek
authors.affiliation: Peatland Ecology Group, Department of Forest Sciences, University of Helsinki P. O. Box 27, Helsinki, FI-00014, Finland ; Division of Atmospheric Sciences, Department of Physics, University of Helsinki P.O. Box 68, Helsinki, FI-00014, Finland.
authors.forename: Eija
authors.initials: E
authors.lastname: Juurola
authors.affiliation: School of Forest Resources and Environmental Science, Michigan Technological University 1400 Townsend Drive, Houghton, Michigan, 49931.
authors.forename: Rodney A
authors.initials: RA
authors.lastname: Chimner
authors.affiliation: School of Forest Sciences, University of Eastern Finland P.O. Box 111, Joensuu, FI-80101, Finland ; School of Computing, University of Eastern Finland P.O. Box 111, Joensuu, FI-80101, Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Mehtätalo
authors.affiliation: Peatland Ecology Group, Department of Forest Sciences, University of Helsinki P. O. Box 27, Helsinki, FI-00014, Finland ; School of Forest Sciences, University of Eastern Finland P.O. Box 111, Joensuu, FI-80101, Finland.
authors.forename: Eeva-Stiina
authors.initials: ES
authors.lastname: Tuittila
keywords: chlorophyll fluorescence; ecophysiology; light responses; peatland; restoration