ALTITUDINAL ZONATION IN THE MOUNTAIN FORESTS OF MT HAUHUNGATAHI, NORTH ISLAND, NEW-ZEALAND

The altitudinal ranges for woody species, in the zone from 750 m to tree-line (c1160 m), are described for the western slopes. The patterns of species abundances over the altitudinal sequence indicated major zones (ecotones) of species compositional change at tree-line and at c1050 m. This latter boundary marks the upper altitudinal limit for many important tree species of the lowland and montane forest zones (eg Dacrydium cupressinum, Podocarpus spicatus and Nestegis cunninghamii), and the first appearance of species characteristic of the sub-alpine forest zone (eg Phyllocladus alpinus and Dacrydium biforme). Ordinations of stand density and basal area data revealed a highly significant correlation between stand loadings on the first axis and altitude. Also, a break in the altitudinal arrangement of sample stands is apparent at c1050 m, confirming the change from montane to subalpine forest suggested by indirect gradient analysis results. -from Authors