Drs. Wofsy and Bazzaz will determine net exchange rates for important gases between the atmosphere and a forest ecosystem in New England. The purpose is to quantify atmosphere-biosphere exchange rates for CO2, H2O, O3, NO, NO2, NOy (sum of all oxidized nitrogen), and total hydrocarbons in a mixed hardwood stand in Harvard Forest, Petersham, Massachusetts. The measurements will help to elucidate the response of the system, and its main component parts, to natural environmental variations and pollutant inputs, providing data essential for understanding ecosystem response to climate change and global pollution. Rates of gas exchange for the whole ecosystem will be measured using eddy-correlation methods, for 2 or more annual cycles. Soil emission rates will be monitored, and exchange rates for intact leaves will be measured throughout the forest canopy. Concentrations in the atmosphere will be monitored continuously at 8 levels from the ground to 30m. A diagnostic model for exchange of biologically active gases will be developed for the ecosystem, to aid in elucidating the factors regulating gas exchange. The study will determine net ecosystem exchange (NEE) of CO2 and other gases in the forest in all seasons, will define contributions to NEE of soils and of leaves throughout the canopy, and will examine possible influence of O3, nitrogen oxides and variations in solar irradiance, temperature, humidity, on CO2 fixation and other exchange processes. The role of gaseous hydrocarbons in the forest carbon budget will be defined. Dr. Wofsy and Bazzaz are leaders in their fields, and the institutional support for this research is outstanding.
