摘 要(英文)：Continuous measurements of carbon dioxide using the eddy covariance (EC) technique were made in 2003 at three ChinaFLUX forest sites, including a temperate mixed forest (CBS), a subtropical evergreen coniferous plantation (QYZ) and a subtropical
evergreen broad-leaved forest (DHS) along the North–South Transect of Eastern China (NSTEC). The three forest sites are
influenced by Asian monsoon climate to varying degrees. The environmental controls on the seasonal variations of ecosystem
apparent quantum yield (a), maximum photosynthesis rate (Pmax) and ecosystem respiration (Re) were investigated in the three
forest ecosystems. At the CBS site, temperature was found to be the dominant factor controlling the seasonal patterns of ecosystem
a and Pmax, while the phenology, which was mainly embodied by the development of LAI, also displayed important influence. The
seasonal patterns of a and Pmax at QYZ were mainly ascribed to vapor pressure deficit (VPD). Ecosystem a decreased with
increasing VPD and Pmax decreased below and above the optimum VPD as a result of the Asian subtropical monsoon climate which
resulted in the extremely high temperature and low moisture. At the DHS site, ecosystem a only appeared weak negative correlation
with temperature, while there was no obvious dominant factor controlling the seasonal pattern of ecosystem Pmax. The ecosystem
respiration of the three forest ecosystems could be estimated well by temperature with an exponential equation. During the growing
season, the ecosystem a, Pmax and Re at CBS were much stronger than that of QYZ and DHS. The Re at CBS was more sensitivity to
temperature than that of QYZ and DHS, so its response to changing climate deserved more attention in the evaluation of the carbon
budget of such ecosystem.
Seasonal variations of ecosystem apparent quantum yield (a)and maximum photosynthesis rate (Pmax) of different forest ecosystems in China