Flora & Fauna

Fossils

Fossils are the remains or traces of animals and plants that have been preserved in rocks. Most fossils occur in sedimentary rocks where the skeletal remains of organisms have been buried within layers of sand and mud.

The largest head of a reef coral (Plesiastrea) so far found in the Waitakere Ranges (specimen from Maori Bay)

All the fossils in the Waitakere Ranges occur in sedimentary rocks, mostly in mudstone or sandstone, but sometimes also in sandy conglomerate beds. Virtually all of these fossil-bearing sedimentary rocks belong to the Nihotupu Formation, which accumulated on the deep-water lower slopes of the Waitakere Volcano and now can be seen around the eastern and northern sides of the Waitakere Ranges.

Common members of the in-situ deepsea fossil fauna from the sandstone and mudstone beds south of Muriwai

The sedimentary rocks of the Waitakere Ranges accumulated on the floor of the sea between 20 and 16 million years ago, during the early Miocene Period, and thus this is the age of all the fossils found within them. Around 300 different species of macrofossil have been recorded from the Waitakere Ranges, with specimens held in the collections of Auckland University and the Auckland War Memorial Museum.

Foraminiferal microfossils from the sedimentary rocks of Waitakere. Scale is 0.1mm long.

Twenty-eight of these fossil species have been described as new and have type specimens and type localities from the Waitakere Ranges. Very few of these new, mostly deepsea, species have yet been found elsewhere.

From ‘Fossils: Relics of the Past’ Bruce W Hayward, Waitakere Ranges

Rainforest of the Waitakeres

Although the bulk of the kauri (Agathis australis) has been milled, there is plenty of evidence of its former extent throughout the great rectangle from Muriwai south to Titirangi, and from the west coast to the eastern foothills — even to the Henderson lowlands now in farmland. Huge sawn stumps, less evident as time goes on, can sometimes still be traced in the second growth, and for the observant the remains of tramways and dams can be found.

When viewed from a little distance the mature forest is impressive and beautiful Predominantly rather sombre, it still delights the eye with its billowing masses of green, ranging from the olive tones of tawa to the grey-green of kahikatea (Dacrycarpus dacrydioides) and the honey-green of rimu or the dark shining green of puka (Griselinia lucida). Frequently, it is the dense green of kauri crowns that dominate in a jumbled fretwork against the sky. Splashed throughout, according to season, will be drifts of starry clematis (Clematis paniculata)

Hebe bishopiana – E. Cameron

and Kirk’s shrub daisy (Brachyglottis kirkii) or creamier heketara (Olearia rani)

The largest of the filmy ferns, Hymenophyllum dilatatum – John Braggins

whose bright panicles may cover steep slopes like a powdering of snow, especially along Scenic Drive.

Rata Flowering – Ted Scott

And then, every third summer or so, the crimson tree rata (Metrosideros robusta) will bloom. Nearer the coast and on the lower eastern slopes, kowhai (Sophora sp.)adds gold to the tops, while pohutukawa (Metrosideros excelsa) (blazes brightly.)

From “Rainforest of the Waitakeres ” Lucy Cranwell-Smith (1982) Waitakere Ranges

The Green Kingdom Ferns and Liverworts John Braggins

Ferns and the generally smaller liverworts and mosses are different from the general trees and plants of the forest in that they are spread by spores, tiny structures made up of a cell with a tough outer wall.

Ferns

For the people of Auckland the Waitakere Ranges are ‘fern heaven’. The wonderful, varied topography and high rainfall combine to provide the best conditions for displaying many of our native ferns and bryophytes in profusion. We are especially lucky in New Zealand in that we have so many common and widespread ferns, thus the forest always seems so much richer in ferns here than in other countries.

The spectacular tree ferns, especially mamaku (Cyathea medullaris),

Mamaku, Cyathea medullaris, our largest tree fern – John Braggins

are often the first to catch the eye. Starting usually on old slips or other exposed soil, lines of them mark old roads and slipways and adorn the slopes near roads. This, the largest of our tree ferns, dominates areas where it is established. However, don’t look for it in the dense forest as it is a plant needing light.

The smaller tree ferns are also striking, with the ponga or silver tree fern (Cyathea dealbata) more able to handle drier sites, the wheki (Dicksonia squarrosa) forming stands in damp spots, and katote (C. smithii) confined to cooler forest at higher levels. At the other extreme of size are the many filmy ferns, some delighting the eye with a soft profusion of tiny fronds on tree fern trunks. Others, also usually on tree fern trunks, form tiny fans (Hymenophyllum lyallii),

A tiny filmy fern Hymenophyllum lyallii, which grows on tree fern trunks – John Braggins

while many have triangular fronds through which sunflecks glow in pellucid green. This profusion is at its best in sheltered gullies, especially in wetter areas. Tree fern trunks are a particularly favoured habitat for filmy ferns and those found on them range from the largest (Hymenophyllum dilatatum) to the smallest. Among the more unusual is H. ferrugineum where the fronds are brown because of star-shaped hairs along the veins and margins.

Hymenophyllum ferrugineum has brown hairs on the veins and margins -John Braggins

It is a plant of wetter sites most often on wheki trunks.

From “The Green Kingdom Ferns and Liverworts” John Braggins, Waitakere Ranges

“Nature in Miniature The Mosses” Jessica Beaver

Imagine the bush of the Waitakere Ranges stripped of all its small plants. Much of the character of New Zealand’s wild places is due to mosses and liverworts, the plants collectively known as bryophytes. Individually the bryophytes may be small, but they often carpet ground and trees in abundance, acting as a living mulch for the forest.

Pyrrhobryum mnioides red capsule mouth, operculum and calyptra. Bill Malcolm

With their wide diversity of habitats,forming a dynamic patchwork, the Waitakere Ranges harbour a wealth of mosses. These small plants form an important part of the biodiversity of the region. They have a significant role in sustaining both highly modified and more natural ecosystems, through their abilities to absorb, retain, and slowly release water. They provide homes for invertebrates and nurseries for larger plants, while adding an aspect of aesthetic beauty to the environment, part of its mauri, which can be appreciated by the scientist and the artist in each one of us.

From “Nature in Miniature The Mosses” Jessica Beaver, Waitakere Ranges