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Abstract.-Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, treetops, and branches contain substantial information about tree dimensions that can be used to determine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Chamaecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appropriate conditions, the biomass of ancient forests can be estimated with reasonable confidence.
Introduction
Studies of in situ stumps and logs have revealed general information about the ecology of forest trees growing in different environmental settings at different times in earth history (e.g., Francis 1991; Taylor et al. 1998; Pole 1999; Lehman and Wheeler 2001), but very few studies have rigorously defined the basic paleoecosystem attributes related to carbon accumulation-productivity and biomass. Under appropriate conditions, the combination of tree stumps preserved in growth position and careful analysis of fossil log remnants can be used to characterize the structure, developmental history, biomass, and productivity of an ancient forest ecosystem. Such information can offer independent validation of model-derived estimates of terrestrial biomass and productivity (e.g., Beerling 1999, 2000).
Although there are published methods for estimating the height of fossil trees (Mosbrugger 1990; Niklas 1994) there are no established methods for determining fossil forest biomass. In situations where preservation is good, the remains of fossil forests often consist of stumps, scattered fossil logs of variable length, and upper tree stems (i.e., tree tops). In a companion paper to this one (Williams et al. 2003a), we have used...