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Forest Vines to Snow Tussocks: The Story of New Zealand Plants

Lord Howe Island

Lord Howe Island177,181

Lying about 850 km west of Norfolk at 31 °S Lord Howe Island is much closer to Australia (600 km) than New Zealand (1300 km). The island is crescent shaped and about 10 km long by 3 km at its widest. Like Norfolk it is the remnant of a long extinct volcano, but it is much more mountainous and has much of its original vegetation largely intact. The northern half of the island includes groups of hills, but in the south are two steep mountains — Mt. Gower (875 m) and Mt. Lidgbird (763 m) (Fig. 120). Mild to warm temperatures and ample rainfall support dense forest over most of the island, with shrub associations near the sea on cliffs, and on the mountain tops.

Up to about 300 m there is a relatively tall forest with scattered emergent trees to 20 m in height. In some places and particularly at lower elevations the emergents are of the endemic Ficus columnaris, one of the species of the fig genus known as banyans. In these the spreading branches are supported by innumerable trunk-like 'column roots'. Elsewhere and tending to be at higher elevations the emergents are Cleistocalyx fullageri, which belongs to the fleshy-fruited subfamily of the family Myrtaceae. The main canopy of the lowland forest is about 15m high and composed of a mixture of species of genera not found in New Zealand. Conspicuous are some of the handsome palms for which Lord Howe is noted — Howea forsteriana and H. belmoreana at lower elevations with Hedescepe canterburyana higher up. Both genera are endemic. Among the subcanopy trees and shrubs New Zealand relatives are more frequent page 220
Figure 120 (opposite) Lord Howe Island. Mt. Lidgbird with Howea palms in the foreground. Photo: G. W. Gibbs.

Figure 120 (opposite) Lord Howe Island. Mt. Lidgbird with Howea palms in the foreground. Photo: G. W. Gibbs.

page 221Coprosma putida, Geniostoma petiolosum, Sophora howinsula, Myrsine platystigma, Myoporum insulare, Dysoxylum pachyphyllum, Macropiper excelsum and Bubbia howeana. Bubbia belongs to a primitive flowering family, Winteraceae, which also includes the New Zealand Pseudowintera. Ferns, sedges and grasses are common on the forest floor. Lianes are abundant, but, except for a Clematis, belong to genera not represented in New Zealand. Epiphytes are infrequent.

Above 300 m altitude there is a change to a montane low forest without emergents. A number of the lower altitude species are present here with the addition of Dracophyllum fitzgeraldii, Metrosideros nervulosa and Olearia ballii. The Howea palms are replaced by Hedyscepe canterburyana. Lianes and epiphytes are uncommon in this forest.

On the mountain summits is a low forest or shrubbery 3–4 m high in which tree ferns, Dracophyllum fitzgeraldii and the palms Hedyscepe canterburyana and Lepidorrhachis mooreana are conspicuous. Other species from lower altitudes are also present. Higher altitude species are Negria rhabdothamnoides (an endemic genus related to Rhabdothamnus of New Zealand), Corokia carpodetoides, Coprosma lanceolaris, and in more open places Leptospermum flavescens and Gahnia xanthocarpa. Ferns are abundant on the ground, and epiphytic ferns, mosses and lichens on the branches of the trees and shrubs.

At most places along the coast there is a narrow zone of shrubs tolerant of salt spray. A number of species are present, but only Coprosma prisca provides a link with New Zealand.

With about 230 vascular species Lord Howe has the richest of the subtropical floras resulting no doubt from its more varied topography and nearness to Australia. About 75 species or a bit less than one third are considered to be endemic. Included among them is Carmichaelia exsul, the only member of the genus occurring outside New Zealand.

About 70 species are shared by New Zealand and Lord Howe, but most of these occur in a number of other places as well.