Rare plants of Waima Forest

Forest and Bird, Volume 20, Issue 4, 1 November 1989, Page 37

Rare plants of Waima Forest

by

Lisa Forester

O n cold, south-facing, wind-blasted cliffs along a range which rises to Te Raupua, the highest point in Northland, grows a strange community of plants including two recently discovered species which have been found nowhere else. One is a leathery leaved Olearia which grows into a small tree. The other is a strikingly different Coprosma. Both are seriously threatened by goats and possums. It is remarkable that two such conspicuous plants should have remained undiscovered when the ridgetop above their habitat is well used by trampers. The fact is that their territory is one of the coldest, dampest and most inhospitable places in Northland. The plants grow on the upper slopes of the Waima Range on forest and scrub-covered ledges and near-vertical basalt cliff faces where only the keenest tramper or botanical enthusiast would ever attempt to visit. The story began a few years ago when John Beachman, now District Conservator for the Department of Conservation in Kaikohe, collected, below Hauturu Trig, a robust, shiny leaved Olearia that he did not recognise. The plant, which has large, bronze-backed leaves, was identified as a new species. Anticipating that there might be other rarities John and I made another visit to Hauturu in 1986. Clambering around on the steep cliffs and ledges below the trig we found a Hebe previously known only from similar country in Herekino Forest, south of Kaitaia and from a gorge cut into the Ahipara gumlands plateau. We also found a very odd looking

Coprosma with upright stems which branched sparsely, and with large, distinctive leaves. This Coprosma differs from all the other New Zealand coprosmas in having enlarged leaf bases and greatly-reduced petioles, or stem. The plant grows to around three metres in height, sometimes collapsing down the cliffs and sending up new growth from the old stems. On subsequent visits with botanists Helen and Tony Druce, Anthony Wright and Ewen Cameron we were lucky enough to catch both sexes of the Coprosma at various stages of flowering and we also found plants fruiting. A stem of the Olearia in bud, collected in late November, burst into spectacular sprays of white daisies a week later. Both plants are being described at present. Suspecting that these and perhaps a few other oddities might be found on similar topography in other parts of Northland we began a search of possible habitats. So far we have checked areas in Warawara, Herekino and Waipoua forest without success, but there is still a lot more country to cover. In Waima Forest we have recorded further populations of the Olearia and Coprosma four to five km east below Te Raupua, the highest point in Northland, and below Mt Misery. These preliminary investigations suggest that it is likely that the plants will be restricted to the main Waima Range. A more comprehensive survey of the whole forest is needed and we intend, this year, to produce a status report for the plants as well as a fuller

description of their habitat and associated species.

Ancient Relics?

An intriguing question is whether the new species are ancient in origin, perhaps Ice Age relics clinging tenuously to a remnant of what was a much wider habitat. The total absence of the plants, even as seedlings, in the surrounding bush suggests that they do not compete well in a closed-forest environment. Maybe comparison of the fossil pollens will shed some light on these questions. Tony Druce, who is describing the Coprosma, has found that it is closely related to Coprosma grandifolia, previously regarded as the sole representative of a distinct group.

Goats and Possums

Unfortunately goats and possums are having a heavy impact on the Waima cliff habitats. The skeletal soils, kept damp under the forest canopy, are prone to erosion, making the habitat very fragile. Even human footsteps cause a surprising amount of damage. The Hauturu habitat is in relatively good condition although the Olearia and Coprosma occupy less than a hectare. Elsewhere much of the Coprosma has been chewed to a stubble and only survives in areas too steep or too dense in vegetation for the goats to reach. The Olearia is a little more widely distributed, inhabiting some of the less steep areas and some of the ridgetops. Nevertheless it is still vulnerable as it is

ringbarked by goats and browsed by possums. I have seen trees with piles of possumripped leaves beneath them. There is no doubt that although goats pose the greatest threat, the combination of goat and possum damage has already been devastating. Damage now in some places is such that you find yourself climbing dry, naked faces with patches of rock pushing through the eroding soil. Hook wedges and adventive species find a suitable habitat under ghostly forests of sticks, while occasional terminal bunches of dying leaves are all that remain to tell that here once grew a flourishing Olearia forest.

Hunters

The Department of Conservation employs two full-time hunters in the North. What makes the goat control especially difficult in Waima Forest and throughout most of the rest of Northland’s forests is the lack of boundary fences. Fencing Waima Forest would be a huge and costly task so the goats continue to filter up from scrub and farmland in the valleys below. However, goat control in Waima is seen as a priority and in 23 hunting days spent there recently 122 goats were shot. If goat culling is continued in Waima, as intended, we can look forward to a much brighter future for this unique habitat. It seems astounding that these large and conspicuous plants on the Waima ranges should hide for so long, suggesting, I feel, that Northland is a treasure house for the naturalist and needs proper inventory. I have a suspicion that Waima’s story is not quite finished, that up on those windblown slopes other gems await discovery. Perhaps next time a giant skink, or new insect will be found. Only time will tell. Lisa Forester is a conservation officer with the Kaikohe office of DoC.