Journal ArticleThe oxygen isotope ratio (d18O, SMOW) of atmospheric CO2 is a powerful indicator of large-scale CO2 exchange on land. Oxygen isotopic exchange between CO2 and water in leaves and soils controls the d18O of atmospheric CO2. Currently there is little empirical information on the spatial and temporal variation in the d18O of leaf and stem water in tropical ecosystems. We measured the seasonal dynamics of d18O in atmospheric CO2 and water in different ecosystem compartments in both primary forest and pasture ecosystems in three different regions of the Amazonian Basin of Brazil (Ji-Paraná, Manaus, and Santarém)
