Modern pollen spectra and vegetation of Mt Hauhungatahi, central North Island, New Zealand

Abstract

Moss samples from a range of plant communities on an altitudinal gradient from montane forest to subalpine tussockland and a transect along the tree-line on Mt Hauhungatahi were analysed for pollen content to quantify modern/vegetation relationships. Cluster analysis of pollen percentages from the sites indicated five distinctive vegetation types: (1) montane forest, (2) subalpine forest, (3) subalpine scrub, (4) subalpine fernland and (5) subalpine tussockland. Ordination arranged sites along an open to densely structured vegetation gradient, i.e. from fernland and tussocklnad to forest and dense scrub. Stepwise discriminant analysis selected for pollen proportion of Myrsine (subalpine scrub), Gleichenia (subalpine fernland), Libocedrus (subalpine forest) and Restionaceae (subalpine tussockland) as highly discriminatory variables in relation to vegetation type. High Weinmannia, Nestegis and Cyathea smithii-type pollen values characterized the montane forest.

Comparison of basal area and pollen data for sites in forest indicated Phyllocladus, Weinmannia, Nestegis, Coprosma and Cyathea smithii-type were over-represented. Dacrydium, Podocarpus, Halocarpus and Libocedrus were under-represented. Comparing pollen with basal area within forest sites, two out of five sites showed a significant positive correlation between species ranked by basal area and pollen. Across forest sites, Phyllocladus, Nestegis, Dacrydium and Coprosma pollen counts showed a significant positive correlation with basal area.

Keywords

Palynology, modern pollen spectra, communities, altitudinal gradient, tree-line, cluster analysis, ordination, discriminant analysis, New Zealand.