Smith, Robin , Greenwood, David , Basinger, James .
Plants of the early Eocene Climatic Optimum: assessing ecosystem resilience and diversity in the fossil record of the Okanagan Highlands, British Columbia.
Macrofloras from localities in the Okanagan region of the interior of British Columbia provide a major resource to study the evolution of modern plant lineages during the early Eocene Climatic Optimum (52 - 50 million years ago). The ecologically diverse upland sites in the Okanagan Highlands provide a window on evolutionary processes at a time of rapidly changing climate, and in response to environmental disturbance in a volcanically active region. This project is focused on a largely unstudied Eocene site near Falkland in the southern interior of British Columbia, along with comparative material from correlative sites in the region. Preliminary results are presented with some initial analysis of changes in plant diversity and ecosystem resilience. Overall, 984 specimens were recorded (collected and/or photographed) during the first field season, comprised of leaves, leafy twigs (conifer foliage), fruits, flowers, seeds and cones. Within an intensively sampled 2.5 m vertical section within the site, the most significant shift in plant community composition occurred in the upper 80 cm of the section, above the second of two major volcanic ash layers. Here the proportion of angiosperms to gymnosperms increases significantly compared to lower levels in the section, suggesting a rapid expansion of angiosperms following a major environmental disturbance. This represents an intensification of a general trend in the site towards increasing abundance of angiosperms over time, and a decrease in ecosystem stability (resistance and resilience). Future work will focus on estimation of paleoclimate using leaf physiognomy and the co-existence approach based on climatic tolerances of nearest living relatives.
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1 - University of Saskatchewan, Geological Sciences, 114 Science Place, Saskatoon, SK, S7N 5E2, Canada
2 - Brandon University, Environmental Science Program, 270 18Th Street, Brandon, Manitoba, R7A 6A9, Canada
3 - University of Saskatchewan, Department of Geological Sciences, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada
development and evolution
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM