HR: 1340h
AN: B43B-0283    [Abstracts]
TI: Ecosystem Phenology from Eddy-covariance Measurements: Spring Photosynthesis in a Cool Temperate Bog
AU: Lafleur, P
EM: plafleur@trentu.ca
AF: Department of Geography, Trent University, Peterborough, ON K8P 2W6 Canada
AU: * Moore, T R
EM: tim.moore@mcgill.ca
AF: Department of Geography and Global Environmental & Climate Change Centre, McGill University , 805 Sherbrooke Street West, Montreal, QC H3A 2K6 Canada
AU: Poon, D
EM: diane.poon@gmail.com
AF: Department of Geography and Global Environmental & Climate Change Centre, McGill University , 805 Sherbrooke Street West, Montreal, QC H3A 2K6 Canada
AU: Seaquist, J
EM: jonathan.seaquist@mcgill.ca
AF: Department of Geography and Global Environmental & Climate Change Centre, McGill University , 805 Sherbrooke Street West, Montreal, QC H3A 2K6 Canada
AB: The onset and increase of spring photosynthetic flux of carbon dioxide is an important attribute of the carbon budget of northern ecosystems and we used eddy-covariance measurements from March to May over 5 years at the Mer Bleue ombrotrophic bog to establish the important controls. The onset of ecosystem photosynthesis (day-of-year from 86 to 101) was associated with the disappearance on the snow cover and there is evidence that photosynthesis can continue after a thin new snowfall. The growth of photosynthesis during the spring period was partially associated with light (daily photosynthetically active radiation) but primarily with temperature, with the strongest correlation being observed with peat temperature at a depth of 5 and 10 cm, except in one year in which there was a long snow cover. The vegetation comprises mosses, which are able to photosynthesize very early, evergreen shrubs, which appear dependent on soil warming, and deciduous shrubs, which leaf-out only in late spring. We observed changes in shrub leaf colour from brown to green and concomitant increases in foliar nitrogen and chlorophyll concentrations during the spring in this "evergreen" system. We analyzed MODIS images for periods of overlap of tower and satellite data and found a generally strong correlation, though the infrequent satellite measurements were unable to pick out the onset and timing of rapid growth of photosynthesis in this ecosystem.
DE: 0428 Carbon cycling (4806)
DE: 0476 Plant ecology (1851)
DE: 0480 Remote sensing
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: Fall Meeting 2005