HR: 17:05h
AN: GC54A-05    [Abstracts]
TI: Ecological Impact of Climate Change on Leaf Economic Strategies Across the Paleocene- Eocene Thermal Maximum, Bighorn Basin, Wyoming
AU: * Royer, D L
EM: droyer@wesleyan.edu
AF: Dept. of Earth & Environmental Sciences, Wesleyan University, Middletown, CT 06459, United States
AU: Currano, E D
EM: ecurrano@geosc.psu.edu
AF: Dept. of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
AU: Currano, E D
EM: ecurrano@geosc.psu.edu
AF: Dept. of Paleobiology, Smithsonian Institution, Washington, DC 20560, United States
AU: Wilf, P
EM: pwilf@psu.edu
AF: Dept. of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
AU: Wing, S L
EM: wings@si.edu
AF: Dept. of Paleobiology, Smithsonian Institution, Washington, DC 20560, United States
AU: Labandeira, C C
EM: labandec@si.edu
AF: Dept. of Paleobiology, Smithsonian Institution, Washington, DC 20560, United States
AU: Lovelock, E C
EM: lovelock@umail.ucsb.edu
AF: Dept. of Earth Science, University of California, Santa Barbara, CA 93106, United States
AB: Deciphering the ecological impacts of climate change is a key priority for paleontologists and ecologists alike. An important ecological metric in vegetated settings is the leaf economics spectrum, which represents an adaptive continuum running from rapid resource acquisition to maximized resource retention. This spectrum is comprised of a large number of coordinated traits, including leaf mass per area (LMA), leaf lifespan, photosynthetic rate, nutrient concentration, and palatability to herbivores. Here we apply a recently developed technique for reconstructing LMA to a suite of four isotaphonomic fossil plant sites spanning the Paleocene-Eocene thermal maximum (PETM) in the Bighorn Basin, Wyoming, USA. This technique is based on the biomechanical scaling between petiole width and leaf mass, and it has been calibrated with 65 present-day sites from five continents and tested on two well-known Eocene fossil localities (Bonanza, Utah and Republic, Washington). There are no significant differences in LMA among plants across the PETM. This stasis is present despite a backdrop of extreme climate change during the PETM in this region, including a three-to-four-fold increase in atmospheric CO₂, an ~5 °C rise in temperature, and possible drying. Moreover, quantitative measurements of insect herbivory show, on average, a two-fold increase during the PETM relative to before and after the event. We interpret our results to suggest that leaf-economic relationships can, in some situations, partially decouple. More specifically, our documented increase in insect herbivory during the PETM with no concomitant decrease in LMA implies that during this interval less carbon was being captured by plants per unit of investment. Because the rate and magnitude of climate change during the PETM is similar to present-day anthropogenic changes, our results may provide clues for predictions of ecological impacts in the near future.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0444 Evolutionary geobiology
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1630 Impacts of global change (1225)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting