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| Titel |
Forest floor carbon exchange of a boreal black spruce forest in eastern North America |
| VerfasserIn |
O. Bergeron, H. A. Margolis, C. Coursolle |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 9 ; Nr. 6, no. 9 (2009-09-02), S.1849-1864 |
| Datensatznummer |
250003989
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| Publikation (Nr.) |
 copernicus.org/bg-6-1849-2009.pdf |
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| Zusammenfassung |
This study reports continuous automated measurements of forest floor carbon
(C) exchange over feathermoss, lichen, and sphagnum micro-sites in a black
spruce forest in eastern North America during snow-free periods over three
years. The response of soil respiration (Rs-auto) and forest floor
photosynthesis (Pff) to environmental factors was determined. The
seasonal contributions of scaled up Rs-auto adjusted for spatial
representativeness (Rs-adj) and Pff (Pff-eco) relative to that
of total ecosystem respiration (Re) and photosynthesis (Peco),
respectively, were also quantified.
Shallow (5 cm) soil temperature explained 67–86% of the variation in
Rs-auto for all ground cover types, while deeper (50 and 100 cm) soil
temperatures were related to Rs-auto only for the feathermoss
micro-sites. Base respiration was consistently lower under feathermoss,
intermediate under sphagnum, and higher under lichen during all three years.
The Rs-adj/Re ratio increased from spring through autumn and ranged
from 0.85 to 0.87 annually for the snow-free period. The Rs-adj/Re
ratio was negatively correlated with the difference between air and shallow
soil temperature and this correlation was more pronounced in autumn than
summer and spring.
Maximum photosynthetic capacity of the forest floor (Pff-max) saturated
at low irradiance levels (~200 μmol m−2 s−1) and
decreased with increasing air temperature and vapor pressure deficit for all
three ground cover types, suggesting that Pff was more limited by
desiccation than by light availability. Pff-max was lowest for sphagnum,
intermediate for feathermoss, and highest for lichen for two of the three
years. Pff normalized for light peaked at air temperatures of 5–8°C,
suggesting that this is the optimal temperature range for Pff. The
Pff-eco/Peco ratio varied from 13 to 24% over the snow-free
period and reached a minimum in mid-summer when both air temperature and
Peco were at their maximum. On an annual basis, Pff-eco accounted
for 17–18% of Peco depending on the year and the snow-free season
totals of Pff-eco were 23–24% that of Rs-adj. |
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