{delta}{sup 13}C Of paleosol organic carbon indicates vegetation and climate changes during the past 15,000 years in the southern Great Plains
- Texas A&M Univ., College Station, TX (United States); and others
{delta}{sup 13}C of organic carbon (OC) in soils and paleosols integrates the relative contribution of C{sub 3} and C{sub 4} plants to the soil OC pool. Geographic distribution and relative productivity of C{sub 4} species are both correlated strongly with temperature. {delta}{sup 13}C of paleosol OC should reflect long-term vegetation dynamics and past climatic variation. To understand vegetation and climate dynamics in the Great Plains during the late Quaternary, {delta}{sup 13}C of OC (n=51) in a stacked sequence of 8 paleosols and one modern soil in central Texas was measured. Three distinct periods of low C{sub 4} productivity ({delta}{sup 13}C = -25 to -21 {per_thousand}) occurred between 15,000-8,000 YBP. These events coincided precisely with 3 well-documented episodes of glacial meltwater flux into the Gulf of Mexico (220 km from study area) via the Mississippi River, indicating strong coupling between marine and adjacent continental ecosystems. The effects of glacial meltwater in the Gulf ceased around 8,000 YBP; after this time, relative C{sub 4} productivity was strongly influenced by orbital forcing mechanisms. Holocene altithermal periods were characterized by high relative C{sub 4} productivity at {approx}5,000 YBP ({delta}{sup 13}C = -18.5 {per_thousand}) and {approx}2,000 YBP ({delta}{sup 13}C = -16.7 {per_thousand}). This late Quaternary {delta}{sup 13}C record of relative C{sub 4} productivity is highly correlated with previous climatic reconstructions for this region based on other methods, indicating that {delta}{sup 13}C of paleosol OC may be a useful proxy for paleotemperature in the Great Plains. Furthermore, large shifts in relative C{sub 3}-C{sub 4} productivity during the late Quaternary documented here and elsewhere may have implications for modeling carbon and hydrologic cycles at regional and global scales during this time interval.
- OSTI ID:
- 95857
- Report Number(s):
- CONF-9507129-; ISSN 0012-9623; TRN: 95:004728-0124
- Journal Information:
- Bulletin of the Ecological Society of America, Vol. 76, Issue 2; Conference: 80. anniversary of the transdisciplinary nature of ecology, Snowbird, UT (United States), 30 Jul - 3 Aug 1995; Other Information: PBD: Jun 1995
- Country of Publication:
- United States
- Language:
- English
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