Long-term Carbon Flux Measurements Above a Mixed Forest at Borden, Ontario

The Borden Forest Research Station, in Southern Ontario (44° 19' N, 79° 56' W), has been used to conduct research on forest-atmosphere interactions since 1985. This mixed, predominantly deciduous forest, located in the Great Lakes / St. Lawrence transition zone between temperate deciduous and boreal forest biomes, is a natural re-growth from farmland abandoned in the early 20th century.

Eddy covariance flux measurements of forest-atmosphere exchanges of carbon dioxide, water vapor, energy, and momentum have been made almost continuously at the forest since 1995, making it one of the longest flux records in Canada. Flux data from 1995-2003 have been previously reported, showing the forest to be a low to moderate sink of carbon for this time period, with higher net ecosystem productivity coinciding with an early growing season onset, warmer temperatures, and higher precipitation or photosynthetically active radiation. This paper extends the time series to include flux measurements from 2005-2011. The influence of interannual climate variability on the CO2 exchange is explored across the entire time series in order to elucidate how the forest may respond to a change in climate, especially regarding its status as a carbon sink.