Are there relationships between level of disturbance and net ecosystem carbon exchange?
Out of the approximately 8 Pg (1015 g) of CO2 that are released annually by mankind, only about one half ends up in the atmosphere (Poisson 1998, Prentice and Lloyd 1998). The rest is uptaken by sinks on the land surface and in oceans. Recent research has indicated that terrestrial ecosystems of the northern hemisphere are, for the time being at least, acting as sinks for CO2. Numerous field sites to monitor CO2 exchange between the land surface and atmosphere have been set up across the US, including an eddy covariance flux network and the USDA-ARS rangelands flux network based on the Bowen ratio. Both networks are based on measurements of carbon exchange that average over large spatial scales, and with little consideration of disturbance. For this reason, the overall effects of small-scale disturbance on ecosystem carbon exchange is “averaged out.” We tested whether disturbance is modifying net ecosystem CO2 exchange by making measurements with clear polycarbonate chambers on grassla
