6.1 STRONG LINKS BETWEEN TELECONNECTIONS AND CANOPY CO2 EXCHANGE FOUND AT A PACIFIC OLD-GROWTH FOREST

Variability in three Pacific teleconnection patterns are examined to see if net carbon exchange at a low-elevation, old-growth forest is affected by climatic changes associated with these periodicities. Examined are the Pacific Decadal Oscillation (PDO), Pacific/North American Oscillation (PNA) and the El Niño-Southern Oscillation (ENSO). We use six years of eddy covariance CO2, H2O and energy fluxes measured at the Wind River AmeriFlux site, Washington, USA. The forest transitioned from an annual carbon sink (net ecosystem production (NEP) = + 207 g C m-2 year-1) to a source (NEP =- 100 g C m-2 year-1) during two dominant teleconnection patterns between 1999 and 2004. The carbon sink year (1999) occurred during a strong La Niña while the source year (2003) occurred during El Niño. When climate indices are in-phase, i.e. all are negative (cool) or positive (warm), the greatest anomalies in carbon flux and mechanistic variables (light use-, water use-efficiency) were observed. Annual averages were + 0.63 g C m-2 day-1 (- 0.27 g C m-2 day-1