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Carbon isotope compositions of terrestrial C3 plants as indicators of (paleo)ecology and (paleo)climate
- Kohn, Matthew J.
- Proceedings of the National Academy of Sciences of the United States of America 2010 v.107 no.46 pp. 19691-19695
- C3 plants, C4 plants, altitude, atmospheric precipitation, biomass, carbon, carbon dioxide, climate, ecosystems, forests, isotopes, latitude, models, paleoecology, temperature
- A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ¹³C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ¹³C of atmospheric CO₂, these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7-8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward dry ecosystems, although wet ecosystems are also represented. Unambiguous isotopic evidence for C4 plants is lacking prior to 7-8 Ma, and hominid ecosystems at 4.4 Ma show no isotopic evidence for dense forests. Consideration of global plant biomass indicates that average δ¹³C of C3 plants is commonly overestimated by approximately 2[per thousand].