Contents

Introduction

The middle Eocene (ca. 45 My), floodplain and swamp forests of Axel Heiberg Island (79°55 N, 89°02 W) became a focus for research in 1986 (Basinger 1986). These large-biomass, Metasequoia-dominated forests grew in a warm-temperate climate at a paleolatitude of ca. 77°N. The forest-bearing sediments are extensive (>500 km2) and the preservation of plant remains is remarkable. The extensive, in situ mummification of litter, stumps, boles, roots, seeds, soils etc. represents a unique opportunity to reconstruct a terrestrial ecosystem and several aspects of the climate it was subject to. There are no modern analogs of these forests which, judging from their biomass and individual tree diameter growth rates, were important terrestrial C sinks that grew in 24 hours of sunlight for 3 months, then had to use stored C during three months of darkness when it apparently was not particularly cold (Basinger 1991). Given the extent of tropical forests during the Eocene (e.g. Wolfe 1985; Christophel and Greenwood 1989; Romero 1986; Axelrod and Raven 1978), the Eocene forests of Axel Heiberg Island probably represent the maximum terrestrial ecosystem productivity achievable near the poles.