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Late neogene climate change and the geochemical record of C4 plants

Journal Article · · Bulletin of the Ecological Society of America
OSTI ID:95777
 [1]
  1. Cornell Univ., Ithaca, NY (United States)
The d13C difference between C3 and C4 plant tissues preserved in fossil organic matter, soil carbonates, and fossil teeth is a powerful tool for investigating floral changes in ancient ecosystems. Data from all three sources suggest that the expansion of C4 biomass was diachronous, beginning by at least mid-Miocene time. C4 plant expansion took place during an interval characterized by a global shift toward cooler and drier climates, accompanied by (and perhaps driven by) falling CO2 levels. However our knowledge of CO2 levels over the last 20 Ma is not yet sufficient to test the hypothesis that specific expansion events were related to changes in pCO2. Rapid Late Miocene expansion of C4 biomass in the Himalayan foreland is associated with the onset of a strong regional monsoon. The close coupling between oceanographic and terrestrial indicators of climate change and plant community composition suggests that, in this case, increased seasonality rather than CO2 drop was the proximate trigger for the expansion of C4 biomass. An unresolved problem with sedimentary d13C data is whether it primarily records community composition, relative productivity, or preservation differences between plant materials.
OSTI ID:
95777
Report Number(s):
CONF-9507129--
Journal Information:
Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 2 Vol. 76; ISSN BECLAG; ISSN 0012-9623
Country of Publication:
United States
Language:
English