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Using MODIS derived fPAR with ground based flux tower measurements to derive the light use efficiency for two Canadian peatlands
J. Connolly1, N. T. Roulet2, J. W. Seaquist3, N. M. Holden1, P. M. Lafleur, E. R. Humphreys, B. W. Heumann, and S. M. Ward1
1Biosystems Engineering, UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Dublin, Ireland
2Department of Geography and Global Environmental and Climate Change Centre (GEC3), McGill University, Montreal, Quebec, Canada
3Department of Physical Geography and Ecosystems Analysis Geobiosphere Science Centre Lund University Sölvegatan 12, 223 62 Lund, Sweden
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Abstract. We used satellite remote sensing data; fraction of photosynthetically active
radiation absorbed by vegetation (fPAR) from the Moderate Resolution Imaging
Spectroradiometer (MODIS) in combination with tower eddy covariance and
meteorological measurements to characterise the light use efficiency
parameter (ε) variability and the maximum ε
(εmax) for two contrasting Canadian peatlands. Eight-day
MODIS fPAR data were acquired for the Mer Bleue (2000 to 2003) and Western
Peatland (2004). Flux tower eddy covariance and meteorological measurements
were integrated to the same eight-day time stamps as the MODIS fPAR data. A
light use efficiency model: GPP=ε * APAR (where GPP is Gross
Primary Productivity and APAR is absorbed photosynthetically active
radiation) was used to calculated ε. The εmax
value for each year (2000 to 2003) at the Mer Bleue bog ranged from 0.58 g C MJ−1 to 0.78 g C MJ−1 and was 0.91 g C MJ−1 in
2004, for the Western Peatland. The average growing season ε for the Mer
Bleue bog for the four year period was 0.35 g C MJ−1 and for the
Western Peatland in 2004 was 0.57 g C MJ−1. The average snow free
period ε for the Mer Bleue bog over the four year period was
0.27 g C MJ−1 and for the Western Peatland in 2004 was 0.39 g C MJ−1.
Using the light use efficiency method we calculated the
εmax and the annual variability in ε for two
Canadian peatlands. We determined that temperature was a growth-limiting
factor at both sites Vapour Pressure Deficit (VPD) however was not. MODIS
fPAR is a useful tool for the characterization of ε at flux
tower sites.
Discussion Paper (PDF, 593 KB) Interactive Discussion (Final Response, 2 Comments)
Citation: Connolly, J., Roulet, N. T., Seaquist, J. W., Holden, N. M., Lafleur, P. M., Humphreys, E. R., Heumann, B. W., and Ward, S. M.: Using MODIS derived fPAR with ground based flux tower measurements to derive the light use efficiency for two Canadian peatlands, Biogeosciences Discuss., 5, 1765-1794, 2008. Bibtex EndNote Reference Manager
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