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Abstract Detail



The Miocene vegetation and environment of Western North America

Wheeler, Elisabeth [1], Manchester, Steven  [2], Dillhoff, Thomas [3].

The Prequel.  Getting from the Eocene to the Miocene with Woods. Comparing Miocene with Paleogene Wood Anatomical Information from the Pacific Northwest, USA.

Fossil woods are abundant in the Pacific Northwest and provide information about changes in wood anatomical functional traits and tree structure through time as well as changes in floristic composition. The middle Eocene Clarno Nut Beds (66 genera, 76 species) and the middle Miocene Vantage Fossil Forest (28 genera, 40 species) are among the world's most diverse and thoroughly investigated fossil wood floras. Currently, we are studying three late Eocene wood assemblages (at least 25 genera, 33 species) from the vicinity of Post, Oregon, in the Crooked River Basin. Unfortunately, Oligocene woods are rare. Differences between the Clarno (29%), Post (31%), and Vantage (40%) wood assemblages in the incidence of ring and semi-ring porosity provide additional and reliable evidence of an increase in deciduousness through time. There are also Eocene-Miocene differences in porosity within particular families, e.g., Fabaceae, Fagaceae, Juglandaceae, and Ulmaceae. Incidences of other functional traits also change, e.g., vessel diameter and frequency of diffuse porous woods, helical thickenings in vessel elements. These values, when compared to those of different modern forest types, are consistent with the transition from subtropical to temperate forest. Changes in taxonomic composition are also evident. Woods of Magnoliaceae and Lauraceae are common in the middle Eocene Nut Beds, uncommon in the late Eocene Post assemblages, and rare in the middle Miocene Vantage assemblage. Other taxa, like Acer, have the reverse pattern. Additional detailed comparisons of Eocene with Miocene woods can contribute to understanding which traits in which clades had adaptive significance for survival in the face of the changing climates of western North America.  


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Related Links:
InsideWood wood anatomy web site
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1 - DEPT OF WOOD & PAPER SCIENCE, 710 Dixie Trail, Raleigh, NC, 27607, USA
2 - University of Florida, Florida Museum of Natural History, PO Box 117800, Gainesville, FL, 32611, USA
3 - 10521 37th St SE, Lake Stevens, WA, 98258, USA, 425-335-4573

Keywords:
Wood anatomy
secondary xylem
Miocene
Eocene
functional traits.

Presentation Type: Symposium or Colloquium Presentation
Session: C2
Location: Salmon/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 3:30 PM
Number: C2009
Abstract ID:377
Candidate for Awards:None


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