Articles | Volume 14, issue 2
Biogeosciences, 14, 257–269, 2017
Biogeosciences, 14, 257–269, 2017

Research article 18 Jan 2017

Research article | 18 Jan 2017

Species-specific temporal variation in photosynthesis as a moderator of peatland carbon sequestration

Aino Korrensalo1, Pavel Alekseychik2, Tomáš Hájek3, Janne Rinne4, Timo Vesala2,5, Lauri Mehtätalo6, Ivan Mammarella2, and Eeva-Stiina Tuittila1 Aino Korrensalo et al.
  • 1School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
  • 2Dept. of Physics, University of Helsinki, Helsinki, Finland
  • 3Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
  • 4Dept. of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
  • 5Dept. of Forest Sciences, University of Helsinki, Helsinki, Finland
  • 6School of Computing, University of Eastern Finland, Joensuu, Finland

Abstract. In boreal bogs plant species are low in number, but they differ greatly in their growth forms and photosynthetic properties. We assessed how ecosystem carbon (C) sink dynamics were affected by seasonal variations in the photosynthetic rate and leaf area of different species. Photosynthetic properties (light response parameters), leaf area development and areal cover (abundance) of the species were used to quantify species-specific net and gross photosynthesis rates (PN and PG, respectively), which were summed to express ecosystem-level PN and PG. The ecosystem-level PG was compared with a gross primary production (GPP) estimate derived from eddy covariance (EC) measurements.

Species areal cover, rather than differences in photosynthetic properties, determined the species with the highest PG of both vascular plants and Sphagna. Species-specific contributions to the ecosystem PG varied over the growing season, which, in turn, determined the seasonal variation in ecosystem PG. The upscaled growing season PG estimate, 230 g C m−2, agreed well with the GPP estimated by the EC (243 g C m−2).

Sphagna were superior to vascular plants in ecosystem-level PG throughout the growing season but had a lower PN. PN results indicated that areal cover of the species, together with their differences in photosynthetic parameters, shape the ecosystem-level C balance. Species with low areal cover but high photosynthetic efficiency appear to be potentially important for the ecosystem C sink. Results imply that functional diversity, i.e., the presence of plant groups with different seasonal timing and efficiency of photosynthesis, may increase the stability of C sinks of boreal bogs.

Short summary
Photosynthetic parameters of peatland plant species were measured over one growing season in an ombrotrophic bog. Based on these measurements, ecosystem-level photosynthesis was calculated for the whole growing season and compared with an estimate derived from micrometeorological measurements. These two estimates corresponded well. Species with low areal cover at the site but high photosynthetic efficiency appeared to be potentially important for the ecosystem-level carbon balance.
Final-revised paper