Articles | Volume 6, issue 2
Biogeosciences, 6, 225–234, 2009

Special issue: Peatlands and the carbon cycle – from local processes to global...

Biogeosciences, 6, 225–234, 2009

  19 Feb 2009

19 Feb 2009

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. Lafleur4, E. R. Humphreys5, B. W. Heumann6, and S. M. Ward1 J. Connolly et al.
  • 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, Sölvegatan 12, 223 62 Lund, Sweden
  • 4Department of Geography, Trent University, Peterborough, Ontario, Canada
  • 5Department of Geography, Carleton University, Ottawa, Ontario, Canada
  • 6Department of Geography, Carolina Population Center, University of North Carolina at Chapel Hill, USA

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 calculate 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 for the Mer Bleue bog over the four years 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.

Final-revised paper