At the time of European settlement some lowland areas, particularly in the North Island, were occupied by bracken fern or shrubland dominated by manuka (Leptospermum scoparium) and/or kanuka (Kunzea ericoides). It is now believed that these areas were originally largely under forest, which was destroyed and prevented from returning by repeated fires of both Maori and natural origin. Many of the fires caused by the Maori were accidental, no doubt, but others were deliberate to encourage the growth of bracken fern whose rhizomes were an important source of starch.

Much of the eastern side of the South Island, as well as the Southland Plain, supported native grassland: short tussock grassland on the driest sites (the Marlborough Plains and adjacent hill country, the Canterbury Plains and foothills, and the Central Otago hill country) and tall tussock grassland of red tussock (Chionochloa rubra) on the moister Southland plains and eastern Otago hills. For some time it was assumed that the short tussock grassland was the original vegetation cover; the regions in which it predominated seeming too dry to support forest. When exotic trees were planted and thrived, there must have been some doubt about this view, but it was not until relatively recent times that evidence came to light indicating that these areas of short tussock grassland originally supported forests and forest/tussock shrubland mosaics. This evidence, to quote Molloy,¹¹⁷ includes 'surface logs and forest wind throw hummocks and hollows in now tree-less areas; buried wood, charcoal, and other plant remains; buried (forest) soil profiles; and a number of relict plants and soils'. It is suggested that forests, particularly in the east of the country, became more susceptible to fire following a change to more variable climates with periodic droughts after about 1800 years ago.¹¹⁸

Identification of wood fragments has allowed a generalised reconstruction of these former Canterbury forests.¹¹⁹ On the western ranges bordering the plains, beech forest extended in most places from tree page 148line down to about 1000 m altitude. Below this, down to about 400 m, came a mixed beech-podocarp forest, and on the plains themselves from 300 m to sea level, there was a type of conifer broadleaf forest dominated by matai (Prumnopitys taxifolia) and totara (Podocarpus totara). Near the sea on swampy sites were stands of kahikatea (Dacrycarpus dacrydioides) forest, of which Riccarton Bush is a surviving example. Older, shallow soils were occupied by low forests of kanuka (Kunzea ericoides), which may, in part at least, have resulted from natural fires. Following the extensive destruction of the forests by fire during the period when the Maori was hunting moas in Canterbury, the higher altitude forests on the inland ranges were replaced by shrubland and narrow-leaved snow tussock (Chionochloa rigida), which moved down from higher altitudes, and red tussock (C. Rubra) which moved out from poorly drained sites on to sometimes quite well-drained hillsides. On the plains themselves, short tussock grassland became established — 'The species

Figure 81 Short tussock grassland dominated by fescue-tussock (Festuca novaezelandiae) on the Mt. Hay Station, Tekapo, central South Island. Photo: E. J. Godley.

page 149forming this grassland would have come largely from river and stream bed floras, from small enclaves of tussock within the forest, from the florulas of rock outcrops, and from among the species with short life-cycles from the alpine snow tussock above.'¹²⁰

Short tussock grassland (Figs. 81, 82) is characterised by the light brown tufts, up to about half a metre high, of hard tussock (Festuca novae-zelandiae) together with silver tussock (Poa cita = P. caespitosa), blue tussock (Poa colensoi) and blue wheat grass (Elymus rectisetus). The most

Figure 82 Short tussock grassland mostly of Festuca novae-zelandiae on hills north of the upper Waitaki River.
Drought resistant shrubs grow on rock outcrops and along the bottoms of gullies where more moisture is available.
Photo: J. W. Dawson.

page 150

Figure 83 Matagouri or 'Wild Irishman' (Discaria toumatou) showing spines and flowers.
Photo: J. W. Dawson.

conspicuous shrub, particularly on stony, moister sites, is matagouri or 'wild Irishman' (Discaria toumatou) (Fig. 83). Matagouri is freely branched and interlaced and set with sharp spines that make it very unpleasant to push through. Small leaves are produced in the spring, but the shrubs are quite leafless during the summer. Two leafless brooms, Carmichaelia petriei and C. robusta, with slender switch-like branches, may stand above the tussocks in drier sites, while among smaller shrubs are Pimelea oreophila and Styphelia nesophila (= Cyathodes fraseri). Notable among the larger herbs is the Spaniard Aciphylla subflabellata, whose close rosettes of much-divided leaves look like clusters of grey, slender, sharply-pointed knitting needles (Fig. 84) and whose equally spiny bracts form cage-like enclosures for the seeds (Fig. 85). The golden Spaniard (A. aurea) also often descends into short tussock grassland from higher altitudes.

One of the driest regions supporting short tussock grassland was the Central Otago hill country and here overgrazing with sheep and the later depredations of rabbits reduced the landscape to virtual desert (Fig. 86). The tussocks were largely replaced by grey patches of Raoulia australis, unflatteringly termed 'scabweed'.

Let us return to the red tussock grassland at the moister southern end of the South Island. A recent study¹²¹ of fossil pollen from bogs built up over the past 12000 years on the Longwood Range in Southland, indicates that forests also covered the southern end of New Zealand until about 1000 years ago. The species represented suggest that kahikatea (Dacrycarpus dacrydioides)-dominated forest occupied moister and swampy sites, rimu (Dacrydium cupressinum)-dominated forest drier sites and silver beech (Nothofagus menziesii) forest the higher altitudes.

After 1000 B.P. (before present) the proportion of forest pollen decreased and spores of bracken fern and grass pollen increased. After 700 B.P. there was a striking upsurge of bracken spores followed by a

Figure 84 (left) Aciphylla subflabellata with male inflorescences.
Photo: J. W. Dawson.

Figure 85 (above) Aciphylla subflabellata. Seedhead with most of the bract segments aligned vertically to form a cage around the seeds.
Photo: J. W. Dawson.

page 152peak of grass pollen: 'We conclude that localised burning took place shortly after the arrival of Polynesians in Southland, which was followed some 200 years later by wholesale destruction of lowland forest by fire. Immediately after the destruction of the forests fernland established, but, with continued burning, grassland began to spread … The first European settlers found the Southland Plains in shrubland, fern, and tussock, with indications in some areas that succession back to high forest had begun.' A similar sequence has been described from Lake Poukawa in the eastern North Island.¹²²

Thus it seems that in their original state, before the increasing frequency of natural and human-caused fires over the past few thousand years, the lowlands of New Zealand had few sites not occupied by forests. In such open habitats as there were, establishment of trees would have been precluded by some localised environmental factor: periodic flooding and disturbance of parts of riverbeds normally above water level; excessive salinity in some coastal sites; excessive drainage and sparse soil of cliffs and bluffs in the drier eastern part of the country, and the infertile soils, containing varying concentrations of toxic metals (nickel, chrome, magnesium), derived from the ultramafic rocks more commonly known as 'serpentine'.

Figure 86 A barren landscape near Bannockburn, Central Otago. The hillside in the foreground above the road has patches of 'scabweed' (Raoulia australis).
Photo: J. W. Dawson.

Figure 87 The Rakaia River, a typical braided river of the Canterbury Plains.
Photo: V. C. Browne.

Lowland bogs and swamps would also have been treeless, but as these alter with time under the influence of plant cover and generally give way to forest, they have already been considered in Chapter 4.