The question of whether tropical forests are carbon sinks or sources is controversial. On the one hand, previous measurements using eddy covariance indicate that it's a sink, and on the other hand biomass based measurements indicate that it's in a zero state of net carbon dioxide fixation. Predictions on whether or not tropical forests will become sources or sinks with climate change depend on our understanding of how gross photosynthesis and respiration will change with climate. Stable carbon and oxygen isotope ratios of ambient carbon dioxide can provide us with a means of disentangling these two processes. It is important, however, to know the extent of respired carbon dioxide recyling before this method can be applied.

Sample Publications

Medina E., Francisco M., Sternberg L., Anderson W.T. Isotopic signatures of organic matter in sediments of the continental shelf facing the Orinoco Delta: Possible contribution of organic carbon from savannas. Estuarine Coastal and Shelf Science 63: 527-536. 2005.

Greaver T., Sternberg L da S. L., Schaffer B., Moreno T. An empirical method of measuring CO2 recycling by isotopic enrichment of respired CO2. Agricultural and Forest Meteorology 128: 67-79. 2005

Sternberg, L da S.L. and DeAngelis , D. Carbon isotope composition of ambient CO2 and recycling: a matrix simulation model. Ecological Modelling 154: 179-192. 2002

Yakir , D., Sternberg L da S.L. The use of stable isotopes to study ecosystem gas exchange. Oecologia 123:297-311. 2000.

Sternberg L da SL, Moreira , MZ, Martinelli , LA , Victoria RL, Barbosa EM, Bonates LCM and Nepstad DC . A comparison of carbon dioxide recycling between two Amazonian tropical forests. Agricultural and Forest Meteorology 88:259-268. 1997 .