Fluxes of CO2 above a plantation of Eucalyptus in southeast Brazil

摘要: Eddy-covariance measurements of net ecosystem exchange CO2 (NEE) and estimates gross productivity (GEP) respiration (RE) were obtained in a 2–4 year old Eucalyptus plantation during two years with very different winter rainfall. In the first (drier) annual NEE, GEP RE lower than sums second (normal) year, conversely total respiratory costs assimilated carbon higher dry normal year. Although primary production (NPP) was 23% that decrease use efficiency (CUE = NPP/GEP) 11% autotrophic utilized more resources first, second, year. The time variations NEE followed by NPP, because these young plantations is largely dominated heterotrophic plays only relatively minor role. During season pronounced hysteresis observed relationship between photosynthetically active radiation, fluxes inversely proportional to humidity saturation deficit values greater 0.8 kPa. Nighttime calm conditions when friction velocity (u*) below threshold (0.25 m s−1) estimated based on Q10 temperature-dependence adjusted separately for classes soil moisture content, which regulated temperature sensitivity