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- Title
Reconstructing the response of C<sub>3</sub> and C<sub>4</sub> plants to decadal-scale climate change during the late Pleistocene in southern Illinois using isotopic analyses of calcified rootlets
- Authors
Wang, Hong; Greenberg, Sallie E.
- Abstract
Abstract: The δ 13C and δ 18O values of well-preserved carbonate rhizoliths (CRs) provide detailed insights into changes in the abundance of C3 and C4 plants in response to approximately decadal-scale changes in growing-season climate. We performed stable isotope analyses on 35–40 CRs sampled at 1-cm intervals from an 18-cm-thick paleosol formed in southern Illinois during Wisconsin interstadial 2. Minimum δ 13C values show little variation with depth, whereas maximum values vary dramatically, and average values show noticeable variability; maximum δ 18O values vary less than the minimum δ 18O values. These findings indicate that a diverse and stable C3 flora with a limited number of C4 grass species prevailed during this interval, and suggest that the maximum growing-season temperatures were relatively stable, but minimum growing-season temperatures varied considerably. Two general patterns characterize the relationships between the δ 13C and δ 18O values obtained from the 1-cm samples. In some cases, low δ 13C values correspond to low δ 18O values and high δ 13C values correspond to high δ 18O values, suggesting that cooler growing-season temperatures favored C3 and warmer growing-season temperatures favored C4 plants. In other cases, low δ 13C values correspond to high δ 18O values, likely suggesting that wetter growing-season conditions were favorable to C3 plants. The high density of well-preserved CRs in this paleosol provides a unique opportunity to study detailed ecological responses to high-resolution variability in growing-season climate.
- Subjects
ILLINOIS; CLIMATE change; PLEISTOCENE stratigraphic geology; STABLE isotopes
- Publication
Quaternary Research, 2007, Vol 67, Issue 1, p136
- ISSN
0033-5894
- Publication type
Article
- DOI
10.1016/j.yqres.2006.10.001