T237 Insights from Microfossils and Their Modern Analogs: From Traditional and Emerging Approaches, to Critical Re-Evaluations (Posters)

Wednesday, 18 October 2023
8:00 AM - 5:30 PM
Hall B

PRELIMINARY ESTIMATES OF CANOPY STRUCTURE FROM THE LATE PALEOCENE TO EARLY EOCENE IN THE BIGHORN BASIN

Paper number: T237-4
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Canopy structure—the openness of a canopy—is a critical component of ecosystems. Changes in canopy structure play a role in ecological interactions (e.g., productivity, landscape stability, the composition of faunal communities, and mammal evolution) and can influence the Earth’s climate (e.g., albedo, hydrological and carbon cycling). Despite being a vital component of terrestrial ecosystems, deficiencies in existing proxy methods have necessitated higher-resolution analyses of canopy structure throughout deep time. Here, we study the relationship between canopy structure and climate change during the late Paleocene-early Eocene (~59-53 Ma) in the Bighorn Basin, Wyoming. This interval may provide good analogs for future climate change as Earth transitioned from a ‘warmhouse’ to a ‘hothouse’ punctuated by several hyperthermals with elevated atmospheric CO2 levels. We used a new canopy structure proxy based on leaf cell morphology to reconstruct leaf area index, a measure of canopy density (LAI; foliage area (m2)/area of ground(m2)) for eight localities. Our preliminary results find an ~51% decrease in LAI from the late Paleocene to the Paleocene-Eocene Thermal Maximum (PETM) hyperthermal (Paleocene, 2.47 m2/m2; PETM, 1.20 m2/m2) and an increase in LAI to 3.92 m2/m2 within the PETM recovery interval. LAI subsequently decreases during the Early Eocene Climatic Optimum (EECO, 1.70 m2/m2). A decrease in LAI during the PETM and EECO is coincident with evidence for increased mean annual temperature and increased water stress within the BHB. Importantly, our results provide a new lens to evaluate the changes in flora and fauna and may provide insight into current and future ecosystem change. Future work will focus on reconstructing LAI in the Bighorn Basin during ETM2 and the Eocene cool period to provide a more complete analysis of the impact of climate change on forest canopy structure.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-395676

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.