The Lowland Forest Community: Mixed Podocarp and Broadleaf

Forest and Bird, Issue 166, 1 November 1967, Page 26

The Lowland Forest Community: Mixed Podocarp and Broadleaf

By

LINDSAY WATSON,

Aged 18, Invercargill

This is the third in a series of articles discussing typical indigenous plant communities. The first article was in the November 1966 issue and the second in the February 1967 issue.

MEW ZEALAND’S forests at low elevations are made up mainly of podocarps—the pines—with which are usually associated some broadleaved species.

A forest is considered to be a climax association; that is, it is the result of a series of herb, shrub, and then tree communities. The forest is made up of several layers, which vary with type and altitude. A typical New Zealand forest would have:

(a) A canopy layer: This contains the tall giants of the forest —the mature podocarps and kauris. These trees protect the underlying plants from great extremes of climate.

(b) A small tree layer: This contains the wineberries, Pittosporums, kamahis, Fuchsias, Pseudopanax, and Neopanax (five-fingers and lancewoods).

(c) A shrub and juvenile tree layer: This contains such plants as Pseudozvintera (horopito), Coprosmas, Sophora (kowhai), and some species of Metrosideros (rata). Tree ferns also are found here.

(d) A ground layer: This contains the lilies, ferns, herbs, mosses, and grasses.

Further subdivisions are usually made, and two special groups of plants are usually present:

(e) Lianes or climbers: containing Rubus (lawyers), supplejack, kiekie, and the Clematis species. (f) Epiphytes and semi-parasites: mistletoes, filmy ferns, hanging ferns, lilies, lichens, and perching trees such as the puka (Griselinia lucida'). Of New Zealand’s approximately 150 tree species, most are found within the forest community—-very rarely do trees occur naturally away from the protection of a forest grouping. The gymnosperms, or pines, in New Zealand are represented by three families: Araucariaceae (kauri), Cupressaceae (kawaka and pahautea), and Podocarpaceae (totaras, miro, matai, kahikatea, monoao, rimu, silver pine, celery pine, and toatoa). Most of these trees are well known and readily identified —some because of their usefulness as timber, a quality not reserved for many of our native trees. The rest of the trees are broadleaved, and these include a wide variety. Maori and European names can often lead to confusion in identification, as some names vary with locality.

The main broadleaved trees tend to be found in the “small tree” or “shrub” layers and include: broadleaf, ngaio, Pseudo panax, the ratas (Metrosideros'), some of which often form part of the canopy layer; Olearias, Pittosp ovums, kowhai,

taraire, Neopanax, lacebarks, ribbonwoods, kamahi (Weinmannia), putaputaweta, kawakawa, Fuchsia, titoki, and sometimes even cabbage trees.

In all the layers of the forest epiphytes and semiparasites exist. Mistletoe, with red or yellow flowers, is a semi-parasite. The lilies (Astelia) perch on many trees, as do the small broadleaves (Griselinia) and the Panaxes and the true kiekie (Freycinetia').

Climbers include the beautiful Clematis species, supplejack, Muehlenbeckia (black vine), and the bush lawyers (Rubus}, which belong to the rose family.

Though the herbs in our forests are relatively few and insignificant, few of them are uninteresting horticulturally or botanically. The orchids are reminders that we were once tropical and subtropical, and we are still well endowed with them, though they do not rival their overseas relatives in size. Of special interest are the hanging ones, of which we have three —two species of Earina and Dendrobium cunning hamii. Of these, only Earina aiitwmnalis has an outstanding scent, and none have flowers over 2.5 cms. across. These are, however, unsurpassed for their minute and intricate detail and delicate colourings.

Other orchids are found in patches on the ground and are mainly Pterostylis (tall, green-flowered), and Corybas (with heart-shaped leaves and dark purple, spider-like flowers).

Other forest herbs include the blueberry (Pianella'), Nerteras, Libertia grandiflora (a larger version of the coastal species), and the lantern berry (Enargea'). Grasses include Chionocloa,

Microlaena, and the hook-grasses (Uncinia), one species of which is dark red.

Mosses and ferns are of special interest in the forest, where they abound in its shade and protection. Here identification is sometimes difficult and it usually helps to group the ferns along these lines : (a) Filmy ferns: delicate, thin fronds (Hymenophyllum and Trichomanes). (b) Aspleniums : light green ferns that produce many hybrids. Most common species are Hen and Chickens (Asplenium bulbiferum) and the hanging spleenwort (A. fiaccidum) . (c) Hard ferns {Blechnum'): these have distinct fertile fronds covered by brown sori. (d) Polypodiums-, a small group of creeping ferns with thick rhizomes (creeping stems). (e) Tree ferns: Cyathea and Dicksonia. (f) Maidhenhair ferns: Adiantum. (g) Shield ferns: Polystichum. (h) Umbrella ferns. ' ■ Mosses provide a study in themselves, and in our forests we have many species. Special note can be made of the Lycopodiums, which can be confused with ferns, but are really a group distinct from both mosses and ferns. Our forests, with their trees and associated flora, provide a beautiful expression of Nature for the plant enthusiast, and it would be a tragedy to the world if they were ever to disappear completely. Our forests gave us a beginning and a home; now they give us sanctuary and peace of mind.