Compound-Specific Stable Carbon Isotope Analysis of Vegetation and Land-Use Change at Laguna Los Mangos, Costa Rica

Authors: Elizabeth Yanuskiewicz*, University of North Carolina - Wilmington, Chad Lane, University of North Carolina Wilmington, Erik Johanson, Florida Atlantic University , Matthew Timothy Kerr, University of Tennessee , Sally Horn, University of Tennessee
Topics: Paleoenvironmental Change
Keywords: compound-specific stable carbon isotope analysis, vegetation, land-use change, maize agriculture, Terminal Classic Drought
Session Type: Paper
Day: 4/4/2019
Start / End Time: 1:10 PM / 2:50 PM
Room: Coolidge, Marriott, Mezzanine Level
Presentation File: No File Uploaded


Compound-Specific Stable Carbon Isotope Analysis of Vegetation and Land-Use Change at Laguna Los Mangos, Costa Rica
E.Yanuskiewicz (University of North Carolina Wilmington), C.Lane (University of North Carolina Wilmington), E. Johanson (Florida Atlantic University), M.T. Kerr (University of Tennessee), S.Horn (University of Tennessee)

We conducted compound-specific stable carbon isotope analyses of n-alkanes (δ13Calkane) in a lake-sediment record from Laguna Los Mangos located in the lowlands of southern Pacific Costa Rica. We combined our results with existing pollen, charcoal, and bulk sediment geochemical proxy data to investigate the vegetation and land-use history in this watershed in the context of the Gran Chiriqui archaeological region before, during, and after the arrival of prehistoric maize agriculture ca. 3350 cal yr BP. Prior to the inception of maize agriculture, our δ13Calkane data corroborate bulk carbon isotope data, showing relatively negative values indicative of prevalent native C3 vegetation. Apparent deforestation and establishment of maize agriculture caused an increase in δ13Calkane and bulk carbon isotope values approximately 3350 cal yr BP, due to replacement of native C3 plants with C4 crops and weeds. Subsequently, sedimentary δ13Calkane values increase during the Terminal Classic Drought indicating either intensified agricultural activity in the watershed or natural increases in C4 vegetation cover due to increased aridity.

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