Ecology Action on a Fringe-Urban Hillside

Rise and put on your foliage, and be seen

To come forth, like the springtime, fresh and green 

Robert Herrick

Under the spreading chestnut tree the village smithy snoozes,

His chest is bare, his matted hair hangs down around his shoeses,

For men may come and men may go but  he goes on the boozes,

Shouting out the battle cry of “Freedom”!

I think that I shall never see
A poem lovely as a tree

Joyce Kilmer

It seems to me that the garden is the only practical way for urban societies to come in close contact with the basic realities of life.

Gene Logsdon

Now we face the question whether a still higher “standard of living” is worth its cost in things natural, wild and free. For us... the right to find an endangered species is as precious as free speech.

Aldo Leopold.

A world without trees,
strong straight and tall;
Is really a world with
nothing at all.

Updated 03 March 2008

What You Will See at Three Streams

This was originally Kauri Forest. Nearly 100 years ago it was cleared for pasture, and then radiata pine plantation, abandoned and untended when we bought it in 1969. Removing most of the pines to replace with amenity species took several years. While the remaining high pines, some pruned up, still dominate the landscape, there is now strong growth of a wide variety and many native species are also regenerating. Colourful garden beds and perennials are found along the central driveway and at open areas.

Native birds include finches, fantails, kereru and tui, plus other immigrants such as rosellas and Californian quail. Insects often thrive on dead trees left in place. Glow-worms are a feature at night along the stream banks with a "grotto" below a culvert on the main drive.

The driveway winds from the highway entrance up with the top boundary of Kauri Grove - where the custodian's house is located. Several walking tracks lead off each side of the lawn down to the streams.

Following the Central Driveway

Contributed by Alan Emmerson 2004

From the main highway you will turn in under a timber arch and follow a concreted driveway down through tree ferns to a parking area with temporary buildings for meetings and storage.

At the bottom of the slope, with flourishing nikau palms and young kauris on either side, is an old timber mill winch stands on the corner of a track down to a bridge over the central stream. The stream path to the right then leads to Kauri Grove.

Straight ahead is another stream valley, featuring swamp cypress (taxodium distichum pukateas and nikaus. To the right, the driveway goes down steeply to a bridge over a dam across the centre stream. On the way down on the right you pass a tall rewa rewa, and on the left, below a phoenix palm, two fine kauri rickers, a miro, a puriri and a (Queensland) firewheel tree.

Below the bridge the two streams join, forming a grotto in which glowworms thrive, continuing far down the shaded stream bank. You will have to come back at night to see them. The dam has raised the stream level upside by several metres, halting erosion and stabilising a richly vegetated valley. We now need to form a fish ladder below the culvert to enable fish to swim right upstream from Lucas Creek (and the Waitemata Harbour) for spawning.

At this point you are in the middle of varied revegetation, below some remaining tall pines. Upstream is a pond, then two islands featuring nikau palms. The eight kauris on the bank above you replaced pines felled only in 1988.

You can follow the path up or downstream - upstream leading to Kauri Grove, or down - past a flourishing redwood (Sequoia sempervirens) to the junction with a third stream which is the Eastern boundary. Nikaus have been planted and regenerate along all the streams. Many, now thirty years old, have handsome, flower-laden trunks.

Click map to enlarge/print

Variety of Species

Another track goes steeply up the hillside ahead, passing a kohekohe, rhododendron, kauri, totara, and many other species, eventually leading to the lawns and gardens at the top.

That attractive ground cover near the driveway and some tracks, flowering in Autumn, is plectanthrus, not a native. It must not be allowed into bush areas where it may prevent regeneration. Close to the streams you see that it is gradually being shaded out by the eminently desirable native parataniwha. Meanwhile it inhibits other weed species.

Upstream beside the path we allow hydrangeas to flourish and add colour in summer, while water irises have established themselves for springtime. Twice a year "red hot" pokers stand out; in January the one day lily (Tigridia) bursts into bloom, followed a month later by belladonna lilies.

In winter brilliant colour is provided by golden Cassias and flaming "pokers". In Spring kumerahou and later, higher, kowhais take over the golden rule.

The main (concrete) driveway continues straight ahead from the bridge, winding up the hill, with a number of sidetracks leading into other areas. A variety of mainly native species can be seen. Just beyond the first ("Cathedral") corner fast-growing redwoods on both sides compete with remnant pines to raise the landscape, followed by kowhai, nikau, puriri, lancewood, kaiwaka, mamakus, miro, rimu and an abundance of lower storey coprosmas, rangiora, kawa kawa, five-finger, pate and mapou nearing the top plateau.

For authorised vehicles, there are parking and passing spots off to the side of the driveway. The first track to the left (Cathedral Corner, a name derived from the ambience of a high stand of pines most of which have now been felled) goes down to a bridge over the back stream, beyond which is a new housing development whose residents are invited to take an active interest in the maintenance and improvement of the area adjacent to them. Some pines near the stream have been removed, because they can become unstable in this situation, and along the boundary we are planting kahikatea, kowhai, puriri and some redwoods.

The next corner above Cathedral opens up an area for groups engaged in field studies, under a large spreading pine which used to accommodate a tree hut for John's children. Beyond it one track leads down to the back stream, and another, straight ahead, provides a particularly lush and beautiful easy walk around and up to the top lawn. Don't miss this. In Spring you will enjoy the sweet aroma of torepapa (or korepapa) which grows along this track. Here also are several good specimens of matai, slow-growing and now all too rare.

Protecting Stream Banks

Recent subdivision higher up has resulted in accelerated erosion along the back stream, which we have left unmanaged as a demonstration of natural forces. Occasionally we have to re-form the streamside track as it is eaten away by erosion. By contrast, the central stream valley has been extensively landscaped. Some channel management is necessary to ensure that fish can swim upstream for spawning.

We find that nikau is the most resilient species to hold stream banks, with the ability to drop down and keep growing when undermined. Pongas and cordylines are more liable to fall over. Big trees, even swamp-loving kahikatea, need to have been established before any “development” took place in the area if they are to withstand the radically changed runoff.

Pukatea track, above the back bridge, leads into a stand of this beautiful tree, some decades from maturity. Close to this stand is our oldest kahikatea, and our oldest tanekaha (celery pine, phyllocladus trichamanoides). Further up the hill tanekaha becomes the dominant regenerating species. Like mapou (myrsine australis) it is common here on the North Shore, filling any open space left by manuka and other colonisers, but eventually the longer-lived kauris, podocarps and other major forest trees take over.

We also have good regeneration of toro (myrsine salicina), relative of mapou (with very different foliage) from an old seed tree, many totaras and some self-sown rewa rewa, which usually prefers volcanic soils to our clays.

Compare Different Foliage

Above Cathedral Corner we can observe two interesting comparisons - a redwood, miro and kaiwaka close enough to see the difference in foliage, and two mature lancewoods displaying juvenile, adolescent and adult foliage. Further up two handsome eucalyptus saligna share the skyline with a Norfolk pine and magnolia, with a 20 year old kauri ricker from Tane Mahuta (warranted by Graham Platt) pushing its way up fast in between. After which kowhais, kauris, kanukas, lacebarks, lemonwoods, kawa kawa, kohe kohe, totaras, rimu, lancewoods and other species surround the house lawns while older tanekahas and pines define the top boundary with Kauri Grove. On this boundary, below the house, is a rare mature specimen of persoonia toru.

Seven separate walking tracks lead from the lawns through differing stands of native bush down to the centre and back streams, but until the Development Plan is operative these are not well maintained. Perennial shrubs and bulbs provide colour in the open most of the year.

Tree Ferns

The Silver Fern, ponga (cyathea dealbata), silver shaded on the underside of the fronds, is a New Zealand symbol, a prolific coloniser throughout the country. We have been letting them grow, providing shade and shelter for other species, but are now selectively removing them where more light is needed. Very high older specimens can be left. Our procedure, in winter, is to use a long handled pruning saw, or just a rake, to reduce the number of fronds to three or four - they rapidly grow again in summer. It's good exercise, like golf. We cut the long fronds and stack them around the stem to decompose, rather than spreading them where they will inhibit seed germination.

There are several other species of tree fern, including the wheki (dicksonia sqarrosa and fibrosa ) and the large, high black stemmed mamaku (cyathea medullaris) some of which die off if the soil dries out too much. Where they remain along the driveway they are quite magnificent.

Orchids

Tiny precious ground orchids occur frequently in spots where the necessary fungus has established. Flowering in December, they are not easily found, and indeed the less their habitat is disturbed the better. It’s just so nice to know they’re here.

Weeds

Weed problems cannot be avoided near an urbanised area. Ginger and privet are ruthlessly eliminated. Some other 'weeds' are tolerated as a temporary ground cover. Over the years, a rationale has developed to cope with weeds in the long term. We like to let everything grow unless or until it becomes a nuisance - bare ground is to be avoided except when deliberately seeding, as with manuka, kumerahou or koromiko.

Adding compost often spreads weeds. But sometimes we do not know what it is or how beautiful it may become, or whether it is interfering with something important. It may be a natural ally, able to grow quite close to another plant without detriment to either. Everything is pretty when young.

Most plants thrive on ample humus, whatever the quality of the local soils. All organic matter converts to humus eventually - insects and microorganisms do the work.