Document: CHR-3-41-6

Structure and biomass of a polar-latitude Eocene forest from the Canadian Arctic.

WILLIAMS, C.J.* ¹, A.H.JOHNSON ¹, B.A.LEPAGE ¹, D.R.VANN ¹ and T.SWEDA ²

University of Pennsylvania, Philadelphia, PA 19104, U.S.A. ¹
Ehime University, Matsuyama, Japan ²

Abstract:
Abundant fossil plant remains are preserved in the high-latitude middle Eocene deposits of the Buchanan Lake formation on Axel Heiberg Island, Nunavut Territory, Canada. Intact leaf litter, logs, and stumps preserved in situ as mummified remains present an opportunity to determine forest composition, structure, and productivity of a Taxodiaceae-dominated forest that once grew north of the Arctic Circle (paleolatitude 7580 N). We excavated 37 tree stems for dimensional analysis from mudstone and channel-sand deposits. Stem length ranged from 1.0 m to 14.8 m (average = 3.2 m). Stem diameter ranged from less than 10 cm to greater than 75 cm (average = 32.2 cm). All stem wood was tentatively identified as Metasequoia. A parabolic taper function was generated from the excavated stems and used to estimate canopy height as a function of stump diameter. Assuming that canopy dominant trees were represented by the largest in situ stumps we calculated a minimum canopy height of 33 m. Buried knots and the presence of branch-free bole wood indicate that this was most likely a closed canopy forest. We used stump diameter data (n =107, diameter > 20 cm) and an uniform canopy height of 33 m to calculate parabolic stem volume and stem biomass for a 2227 m² area of fossil forest. Stem volume equalled 2190 m³/ha and stem biomass equalled 591 Mg/ha. We are currently developing allometric equations for modern plantation grown Metasequoia glyptostroboides to refine and test our standing biomass estimates. Preliminary results indicate that production of branch wood and foliage may increase our estimate of standing biomass by an additional 67 and 8 Mg/ha, respectively.

Keywords: dawn redwood, deciduous conifer, Early Tertiary, tree height

This abstract is being presented at: 5:00 PM in session:
Oral Session #32: Paleoecology.