Species-specific temporal variation in photosynthesis as a moderator of peatland carbon sequestration
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 propertie...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-01-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/14/257/2017/bg-14-257-2017.pdf |
| Summary: | 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 (<i>P</i><sub>N</sub> and <i>P</i><sub>G</sub>, respectively), which
were summed to express ecosystem-level <i>P</i><sub>N</sub> and <i>P</i><sub>G</sub>. The
ecosystem-level <i>P</i><sub>G</sub> was compared with a gross primary production (GPP)
estimate derived from eddy covariance (EC) measurements.<br><br>Species areal cover, rather than differences in photosynthetic properties,
determined the species with the highest <i>P</i><sub>G</sub> of both vascular plants and
<i>Sphagna</i>. Species-specific contributions to the ecosystem <i>P</i><sub>G</sub>
varied over the growing season, which, in turn, determined the seasonal
variation in ecosystem <i>P</i><sub>G</sub>. The upscaled growing season <i>P</i><sub>G</sub>
estimate, 230 g C m<sup>−2</sup>, agreed well with the GPP estimated by the EC (243 g C m<sup>−2</sup>).<br><br><i>Sphagna</i> were superior to vascular plants in ecosystem-level <i>P</i><sub>G</sub>
throughout the growing season but had a lower <i>P</i><sub>N</sub>. <i>P</i><sub>N</sub> 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. |
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| ISSN: | 1726-4170 1726-4189 |