Structure of a near-polar latitude forest from the New Zealand Jurassic

Abstract

A tidal platform at Curio Bay near the southernmost point of the South Island, New Zealand, preserves the petrified remains of an in situ Middle Jurassic forest. The forest grew close to the palaeo-polar circle, but data are not precise enough to tell on which side it lay. A mapped portion of the forest floor provides data on tree density and population structure, allowing comparison with recent forests and with records of other fossil forests. The forest has tree densities similar to many forests growing in low to mid-latitudes today; it appears to have had emergents projecting through a low canopy, and a well-developed undergrowth of smaller gymnosperms and osmundaceous ferns. No aspect of the forest structure uniquely distinguishes it from that of non-polar latitude forests. An extended discussion is given on reconstructing tree height from stump diameter. On the basis of this, a reinterpretation of the structure of an Early Cretaceous fossil forest from Alexander Island, Antarctica, is offered.