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| Titel: |
Forest floor carbon exchange of a boreal black spruce forest in eastern North America |
| Auteur: |
O. Bergeron H. A. Margolis C. Coursolle |
| Verschenen in: |
Biogeosciences |
| Paginering: | Jaargang 6 (2009) nr. 9 pagina's 1849-1864 |
| Jaar: |
2009 |
| Inhoud: |
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. <br><br> 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. <br><br> Maximum photosynthetic capacity of the forest floor (Pff-max) saturated at low irradiance levels (~200 μmol m<sup>−2 s<sup>−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. |
| Uitgever: |
Copernicus GmbH (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 14 van 30 gevonden artikelen
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