Ecology Action on a Fringe-Urban Hillside
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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,
Unlike the wretched man who sees
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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.
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. 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. 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 puriri and some redwoods. 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. 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. Microclimates A feature of the Arboretum is the several microclimates, each favouring different plant species. This is of special interest to botanists. Three Streams is both an arboretum and a regenerating landscape. Exotic and native trees have been planted including over 600 kauris, but substantial areas are left with little or no modification or 'management', to develop a natural succession. The abundance of manuka, kanuka, coprosmas, tanekaha, mapou, kumerahou and other colonising species has maintained ideal nursery conditions for insertion of long-lived forest trees. An 20 year old seedling of Tane Mahuta, the legendary Northland kauri, is now nine metres tall. Although this was originally kauri forest, only 1 “ricker”, less than 100 years old, was left on Three Streams 30 years ago, but there is a fine stand of mature kauris upstream in the Kauri Grove, one of which is six metres in circumference, and a walkway to facilitate access has been started. We have been restoring the kauri presence at Three Streams since 1970, starting with twelve seedlings from the closed-down nursery at Waipoua Forest which we planted around the approximately 60 year old ricker to keep it company. Nine of them survived and are doing well, although we then knew little about their special needs. Several more have since been planted and others have regenerated in the vicinity, which is now an extension of the top lawn near the house. Our main planting was in 1984, when the “reconstructed” NZ Forest Service ended its kauri planting programme and closed the nursery at Sweetwater, above Kaitaia. We obtained 600 of their stock and planted them in suitable spots at Three Streams. Although many were root-bound, having been potted in small bags for a year or more too long, most are now fine young trees. Growth rates have varied according to ground conditions and light – some are twice as high as others, especially where we planted among manukas and pongas and left them for 15 years. Now that we have removed the shading they will soon catch up, having developed good root systems. We have not adopted any special fertiliser regime for them. Most have had nothing except some lime to counteract the acidity from the pines which were here. But we try to maintain a good layer of mulch around them, and this is obviously welcomed. Kauri feeding roots are near the surface and in the forest situation they build up mounds of mulch from their own droppings of foliage and lower branches. This will eventually be a kauri forest again.
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