Dendrochronological studies of indigenous New Zealand trees

Abstract

Extensive collections have been made from trees in the Southern Hemisphere as part of a study to reconstruct past climate from variations in the width of annual growth rings. In connection with this work, cores and discs from 20 New Zealand tree species were collected from 45 sites throughout the North and South Islands. The potential for dendrochronological analysis was assessed for each species, and extensive collections were made of those considered most promising. Libocedrus bidwillii, Phyllocladus trichomanoides, and P. glaucus were used to produce climatically sensitive, dated chronologies in excess of 500 years long. Dacrydium biforme and D. colensoi tend to have less year-to-year variability in growth, but also yield long chronologies in some areas. Phyllocladus alpinus and Agathis australis frequently have pronounced lobate growth, and are datable only at some sites. Twenty chronologies were developed using these 7 species. It is suggested that future dendrochronological studies may be successful with other species, and that the genera Dacrydium, Podocarpus, and Norhofagus offer most potential.