NEW INSIGHTS INTO THE PALEOVEGETATION OF THE ANCIENT UNDERWATER FOREST LOCATED IN THE NORTHERN GULF OF MEXICO

Author

Karla Lizarraga GarciaFollow

Date of Award

Spring 5-2023

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Biological, Environmental, and Earth Sciences

Committee Chair

Andy Reese

Committee Chair School

Biological, Environmental, and Earth Sciences

Committee Member 2

David Cochran

Committee Member 2 School

Biological, Environmental, and Earth Sciences

Committee Member 3

George Raber

Committee Member 3 School

Biological, Environmental, and Earth Sciences

Abstract

A well-preserved remnant of an ancient bald cypress forest (hereafter, Underwater Forest) constitutes the only known archive of a glacial refuge on the once exposed continental shelf of the Northern Gulf of Mexico. This forest existed around 41-72 yBP (MIS 3-5) according to the existing dating methods applied on previous studies. As the climate conditions and sea levels changed, the vegetation of this glacial refuge shifted from bald cypress forests to open marshes, altering the vegetation dynamics. The present research analyzed four new cores (21DF-5A, 21DF-5B, 15DF-6, and 16DF-3A), which provided additional insights into the vegetation that once existed in this Late Pleistocene forest. Comparative analysis was conducted on the four analyzed cores with the 15DF-1 and 15DF-3 cores taken previously from the study area, and these shared strong similarities in vegetation composition and transitional patterns. In all cores, high percentages of Taxodium were evident, resembling a cypress backwater forest that later transitioned to grass dominant environment with high percentages of Poaceae. Cores 16DF-3A and 15DF-6 contain the no-modern analog cypress-alder communities previously described in 15DF-1. Since the pollen assemblages shared strong similarities, the sediments present in these cores correspond to the same event, and existed either 72,000 yBP according to the OSL dating method, or 41-45,000 yBP as determined by the radiocarbon (¹⁴C) technique. Additional dating is necessary to establish an accurate date for the existence and burial of this forest, thus allowing a complete story to be told.

Recommended Citation

Lizarraga Garcia, Karla, "NEW INSIGHTS INTO THE PALEOVEGETATION OF THE ANCIENT UNDERWATER FOREST LOCATED IN THE NORTHERN GULF OF MEXICO" (2023). Master's Theses. 976.
https://aquila.usm.edu/masters_theses/976