TANE 29, 1983

THE SCIENTIFIC RESERVES OF UNIVERSITY. I. GENERAL INTRODUCTION TO THEIR HISTORY, VEGETATION, CLIMATE AND SOILS

by G. M. Thomas and J. Ogden Department of Botany, University of Auckland, Private Bag, Auckland

SUMMARY

The University reserves at Swanson, Huapai, Oratia, Anawhata and Leigh are described and mapped. An introduction to the history of each reserve is followed by a brief outline of the main sources of information relevant to the climate, geography and soils of the area. Topography and vegetation cover are related, and the latter is described in more detail.

INTRODUCTION

The University of Auckland owns or administers a number of scientific reserves, four of which are located in the Waitakere Ranges, west of Auckland City (Fig. 1). The reserves at Swanson, Huapai, and Oratia are examples of kauri (Agathis australis) dominated forest in various stages of regeneration from Leptospermum scrub, with small areas of mature forest. At each the forest canopy also contains podocarp and broadleaf components. At Anawhata and Leigh the reserves also include Leptospermum scrub, but are characterised by regenerating coastal forest with pohutukawa (Metrosideros excelsa) and puriri (Vitex lucens), and a small "ricker" kauri stand at Leigh. In this account the first three reserves (Swanson, Huapai and Oratia) are dealt with in some detail, while the two coastal reserves are briefly covered. This emphasis reflects the amount of ecological research by members of the University staff, Field Club and graduate students which has been carried out in the different areas. Our emphasis is on the vegetation but we have cited the main references dealing with climate and soils. Unreferenced statements are based on the field experience of the authors, or derived from unpublished statements and letters in the files of the University. This paper should be read in conjunction with Ogden (1983 - this volume) which gives more detailed quantitative accounts of the vegetation.

SWANSON

Swanson State Forest 31 is located 27 km west of Auckland City in the eastern foothills of the Waitakere Ranges near the township of 143 KILOMETRES

Fig. 1. Map of the Waitakere Ranges showing the positions of four of the scientific reserves administered by Auckland University.

144 Swanson (Grid reference: Ql 1/497794; NZMS 260 Sheet Qll, Waitakere, 1st Edition, 1979). The property occupies 20. 45 ha on the west side of Tram Valley Road (Fig. 2). This was the first land to become available to the University for use in field studies. It was then Crown land, but was set aside in 1921 for use by the School of Forestry (established in 1924). With the transfer of the school to Canterbury University College in 1931, the control and

Fig. 2. Map of the Swanson reserve.

145 management of the forest reverted to the Botany Department of the University on the understanding that an annual report be made to the Forest Service concerning the state of the reserve and its utilisation by the University in the preceding 12 months. Meanwhile, under Professor Corbin's occupation of the Forestry Chair (from 1926) the building which still occupies the site was completed in 1928 from timber donated to the School by local sawmillers. It comprises a large living room, kitchen, and four bunkrooms, each with four bunks. Electricity is not connected. A feature of this building is the handsome fireplace with its splendid mantelpiece cut from an ancient blackened kauri log long-buried in a swamp. The hut is situated at the end of Tram Valley Road, where it is nestled into a stand of kanuka (Leptospermum ericoides). The Swanson Reserve and hut have been the base for much teaching and research in plant ecology and taxonomy. The following theses or project reports deal in total or part with aspects of the vegetation and are available in the Biological Sciences Library of the University of Auckland. Mirams (1951) studied the factors involved in the natural regeneration of kauri. Aspects of kauri growth, particularly those related to light and temperature, were investigated experimentally by Bieleski (1955). A physiological approach was emphasized in the work of nitrogen fixation in forest Utter by Bucha (1975). Germination and early seedling establishment of Leptospermum scrubland were studied by Mohan (1980). West (1980) gives seed collection data from Swanson and compares them with similar data from Tiritiri Matangi Island. She draws conclusions about native forest regeneration generally. Chambers (1952a) presents a detailed quantitative description of the ecology of the bryophytes and lichens at Swanson and some interesting early photographs of the Swanson hut and adjacent area. An artificial key to the vascular plants common in the Swanson area was constructed by Silvester (1963) and is a useful aid to plant identification.

CLIMATE The regional climate and weather have been described by Kidson (1950). Rainfall records are kept by the Department of Waterworks of the Auckland City Council and the Meteorological Service collects data from and Henderson (No. A64861). Mirams (1951) operated a thermohygrograph in the area for 12 months during the period 1948—1950 and collected data on precipitation, temperature and relative humidity for the same years.

GEOLOGY AND SOILS The area was initially described by Hochstetter (1864) but Hayward (1976) gives a more detailed account. The Waitakere Ranges are

146 composed essentially of fragmented andesitic volcanic rocks. The Swanson area is classified as Lower Miocene (Pareora Series) Waitemata Subgroup sedimentary rocks. The typical rocks are friable yellowish-brown feldspathic sandstones interbedded with light-grey to bluish-black thinner mudstones often well laminated in character. They contain few determinable fossils other than Foraminifera. The New Zealand Soil Bureau (1968) describes the soils of the Waitakere Ranges as interzonal brown granular clays arising from the underlying andesitic parent material. A more specific description of the soils at the Swanson property is given by Bucha (1975). The topsoils are relatively thin, averaging 10 cm. They are greyish-brown to brown, friable and moderately to strongly granular in structure. The topsoils merge gently into brown to yellowish-brown, firm to compact subsoils with blocky to prismatic structure. The clays of the lower horizons are dense, highly plastic, fairly sticky when wet and very friable when dry. Mirams (1967) gives information on soil pH and moisture content.

TOPOGRAPHY AND VEGETATION The landscape at Swanson is dominated by a ridge running from north to south. This ridge is 76. 2 m above sea level at its lowest point and 121. 9 m at its highest. The Swanson Stream flows from north to south at the foot of the slopes and has an average width of 3 m. It is a freshwater stream with a substrate of small boulders and gravel. The ridge and valley sides are covered in kauri-podocarp-hardwood forest typical of the region. The remaining area comprises scrubland (predominantly Leptospermum), abandoned pasture and swamp. The area has been subject to severe disturbance through kauri logging and fire last century and in the early years of this century, and the forest vegetation is largely serai. However, there is no doubt that some of the vegetation survived both axe and fire: a 120 cm diameter kauri on the ridge up which the main track runs has been estimated at 250 years minimum age (from three cores). The vegetation of the area was first described by McKinnon (1930), but his thesis was never deposited in a library, and two maps signed by him appear to be all that remain. The first gives details of topography and the other boundaries of vegetation types and the location of four quadrats within them. Trevarthen (1962) presents a colourful account of the historical background to the vegetation, including logging and fires. The regenerating vegetation was classified on the basis of time since last fire, and maps illustrate the mosaic pattern of communities produced in response to past disturbance and topography. Trevarthen mentions "three distinct types of bush no more than 100 years old - those of the drier ridge tops, those of the valley walls, the mixed bush proper, and

147 finally the facies that fringes the creek or occupies the very deepest and wettest parts of the valleys". This three-fold distinction may still be useful, although recent ordination and classification studies imply a continuous relationship between the different facies. The ridge tops are occupied by stands of young kauri "rickers" with associated kanuka (Leptospermum ericoides) and tanekaha (Phyllocladus trichomanoides). The ricker stands appear to represent a development from areas which regenerated in Leptospermum scrub following the great fires which swept the area in 1840—50. Subsequent less intense ground fires in the ricker have been tentatively dated from fire scars on the kanuka to 1951 and 1955 (Ogden 1983 - this volume). The ridge top facies gives place rapidly to a more diverse assemblage of species on the slopes, with rewarewa (Knightia excelsa) and maire (Nestegis lanceolata) prominent in the canopy and an understorey of tree-ferns, mahoe (Melicytus ramiflorus) and pigeon wood (Hedycarya arborea). The creek side or valley bottom vegetation is characterised by pu tapu ta weta (Carpodetus serratus), nikau palm (Rhopalostylis sapida) some large kanukas, and small shrubby trees (Coprosma australis, Brachyglottis repanda, etc. ). Although all tree ferns are abundant throughout, Cyathea dealbata is most prominent on the ridges, C. medullaris on the slopes and Dicksonia squarrosa in the valley bottoms. The regeneration process at Swanson - the progressive development of Leptospermum and Agathis dominated communities -was given a comprehensive treatment by Mirams (1951, 1957). The physical features of the site were described in detail and some black and white photographs supplement the account of the vegetation. Mirams surveyed kauri size classes in a series of quadrats. A species list based on these quadrats is included in the appendix to his 1951 paper, and includes 71 species of vascular plants (from 31 families) and 25 species of ferns and allied plants. The Auckland University Field Club have undertaken a long-term regeneration study at Swanson. Permanent quadrats have been placed in the reserve and details of species composition will be recorded periodically. A full species list is available from these observations for the pasture and surrounding forest and scrub vegetation (Parris, Dickson and Rae 1970). Not only have the vascular plants been investigated in detail, but also the bryophyte and lichen ecology (Chambers 1952a, b). Forty mosses and 25 hepatics were certainly identified with a further 20 mosses and five hepatics doubtfully present. Each higher plant community within the reserve was surveyed for its bryophyte cover. The most striking feature of the Leptospermum scrub was the almost complete terrestrial carpet of bryophytes and lichens. The dominant moss was found to be Dicranoloma billardieri and this was often associated with lichens of the genus Cladonia, particularly C. floerkeana. The sponge-like nature of the

148 moss carpet makes it important in water storage and it obviously assists in the establishment of seedlings of species which may later dominate the area. In contrast to this, in the areas which may be called mature kauri forest, the terrestrial bryophytes occur in localised and generally pure patches often 0. 5-1 m across. Epiphytic bryophytes become more important in this mature forest.

HUAPAI

In 1947, the liquidators of Northern Fruitlands Limited bequeathed 30 acres (12 ha) of kauri-broadleaf forest in the Huapai area, between Hinau Road and Kauri Crescent, to the University "as a reserve for the preservation of kauri trees" and "for research purposes". An adjoining block of 8 acres (3 ha) was purchased by the University in 1949, bringing the total reserve area to c. 15 ha. (Fig. 3).

Fig. 3. Map of the Huapai reserve.

149 The reserve lies 7. 2 km inland from the West Coast of Auckland in the northern region of the Waitakere Ranges. (Grid reference: Ql 1/435885; NZMS 260 sheet Qll, Waitakere, 1st Edition, 1979). The south-east and north-east boundaries adjoin open farmland and are fenced. Hinau Road runs parallel to the south-west boundary and only the north-west boundary abuts native bush. When the University took control, the reserve was in a reasonably virgin state and largely remains so today except for edge effects near the boundaries and the damage caused by escaped domestic pigs from a neighbouring farm. In February 1950 a series of fires occurred in the upper western end of the reserve, which is now regenerating in Leptospermum. It is of interest to note that a pair of sulphur crested cockatoos (Cacatua galerita) were apparently nesting in the reserve in 1980 and 1981. Three (or possibly four) large kauri trees fell in the reserve in August or September 1954. These were removed and subsequently used for decorating the council chambers at the University. Another large tree fell in 1963, but has not been removed. A large standing dead kauri (visible on the 1980 aerial photograph: Survey No. 5783 Run L/5; 1: 3 500) apparently died rather suddenly in 1966. Thus, at least five of the large kauri trees, for the preservation of which the area was set aside, have died since 1949. The following description comes from Clunie (1967), and from field studies carried out by ecology classes in 1980 and 1981 (Ogden 1983 - this volume).

CLIMATE Data on the general climate of the region were compiled from records of the New Zealand Meteorological Office of recordings at the New Zealand Forest Service station at Woodhill (No A64741). Details of precipitation, temperature, relative humidity, and sunshine are available in graphical form from these data (Clunie 1967). Some data are also availble from the closer station at Kumeu. As at Swanson and Oratia the rainfall is higher than in Auckland City, being in the vicinity of 2 000 mm per annum, with a maximum in the winter months. Temperatures are highest in February and decrease regularly to a minimum in July. Kidson (1950) has covered aspects of the general regional climate.

GEOLOGY AND SOILS The soils are derived from andesitic (basic) tuffs of the Pareora- Southland Series (Miocene). These outcrop to the east of the Miocene andesitic rocks which form a northern extension of the Waitakere Ranges. They are known as Parau clay (Ref. 88b New Zealand Soil Bureau) and have been classed with the brown granular clay subgroup of the brown loam group. The clay fraction of the soils is kaolin, with

150 much hydrated iron oxide. The clays of the lower horizons are dense, highly plastic and fairly sticky when wet. When partly dry they are extremely hard but friable and all horizons have a tendency to break reasonably easily into fine blocky aggregates. Clunie (1967) describes two soil profiles from the reserve, and relates them to the vegetation cover.

TOPOGRAPHY AND VEGETATION A gentle dissected spur with an average altitude of 91 m runs south• west to north-east along the reserve boundary from a fairly level hilltop at the Hinau Road end of the section. From "the plateau" area on this spur the land descends approximately 30 m to the north-west into a damp north-east running gully. This descent is irregular, with several secondary gullies and ridges. The slopes thus have a northerly aspect in general, but in the secondary gullies there are slopes of various aspects. The main ridge, up which a track runs, carries some large (1-2 m DBH) kauris. The upper part of the ridge to the east of this carries a kauri ricker of similar age to that at Swanson. The understorey is dominated by Coprosma arborea and mapou (Myrsine australis) which are both relatively uncommon in Swanson. The two ridges are connected in their upper part by flat land mostly carrying kanuka scrub, but with some areas of more diverse forest with puriri, taraire (Beilschmiedia tarairi), rewarewa and podocarps (Podocarpus totara, Dacrydium cupressinum). Tanekaha is less common than at Swanson. The gully between the two ridges and an extensive area in the centre of the reserve are occupied by "valley bottom" forest, dominated by a few large kahikatea (Podocarpus dacrydioides) with an understorey of tree ferns, nikau palm and cabbage trees (Cordyline australis), and dense tangles of supple-jack (Rhipogonum scandens). The Huapai reserve differs from that at Swanson in having some much larger kauris present. Five of these (127-153 cm DBH) were estimated to age from 456—637 years old (mean = 521) based on eleven increment cores. Two cores from an exceptionally large tree (226 cm DBH) gave an age estimate of 1 151 years, but this must be treated with caution as only c. 30% of the radius was sampled. However, these ages imply that the ridge and probably also the valley areas on the Huapai site, represent remnants of virgin vegetation which have suffered less modification than their equivalents at Swanson.

ORATIA

The Oratia reserve lies in the eastern foothills of the Waitakere Ranges and fronts onto both West Coast Road and Kelly Road, Oratia (Fig. 4). (Grid reference: Rl 1/535748; NZMS 260 Sheet RU, Auckland 1st Edition, 1981).

151 Fig. 4. Map of the Oratia reserve.

This reserve came into existence in 1940, when Mr Herbert Dearsly gave the University two lots in the Oratia area, one bordering on West Coast Road, the other (contiguous with it) on Kelly Road. As at Swanson, the vegetation comprised a mixture of kauri, podocarps and broadleaf species and there, too, research and teaching have been prosecuted with much success. Of particular interest are the actively regenerating populations of Mida salicifolia and Dacrydium kirkii and several good trees of Eugenia (Syzygium) maire. From the sale, with the consent of his surviving relatives, of a house and section on the other side of Kelly Road, bequeathed by Mr Emile Victor Albert to the University, a further lot, adjacent to that on Kelly Road was added to the property in 1966. This incorporated additional trees of D. kirkii into the University reserve.

CLIMATE As with the other reserves described here the climate is mild

152 temperate (Kidson 1950). The closest meteorological station is four kilometers northeast of the reserve at a similar altitude. The Oratia station (No., A64961) is operated by the Plant Diseases Division of the Department of Scientific and Industrial Research. Data from this station were used to infer the climate prevailing in the reserve itself by Shirley (1968). A summary of the rainfall over the period 1921 to 1951 shows that it is spread fairly evenly over the year, but with a maximum in the winter period of April to August and a minimum in March. Studies over the period 1948—50 showed that relative humidity reached a minimum in January (68%) and a maximum in July (88%). Over the same period mean daily temperatures peaked at 24°C in February and dropped to 13°C in July. The reserve is exposed to the southerly quarter and south• westerly winds are predominant.

GEOLOGY AND SOILS Hayward (1976) places the eastern boundary of the Waitakere Subgroup intrusives and subvolcanics (Lower Miocene) and the Waitemata Subgroup flysch (Lower Miocene) near the east of the reserve. It is probable that the reserve contains elements derived from both the feldspathic sandstones and the blue mudstones of the Waitemata Subgroup and the fine grained tuffs of the Waitakere Subgroup. Shirley (1968) considers the soils of the reserve to be a composite of the Parau Hill soil and the Waitakere clay (88bH and 45H respectively of the New Zealand Soil Bureau Bulletin N. S. 5). Detailed data on the soils from four profiles indicated that the soils of the reserve are relatively homogenous and slightly acidic in all horizons. The water content in the top layer was around 65% but this decreased to 30% in the bottom layers.

TOPOGRAPHY AND VEGETATION The land at Oratia is dominated by two ridges (A and B) with their accompanying valleys (A and B) and a third valley (C) perpendicular to the other two (Fig. 4). The stream in this latter valley is relatively permanent but other streams are dry during hot summers. The altitude ranges 30 m within the reserve, the highest point being 91 m on ridge A and the lowest 61 m in valley C. The land from ridge A slopes moderately south to valley A, steeply up the crest of ridge B and less steeply down to valley B. The slopes thus have a northerly or a southerly aspect. Shirley (1968) used a variety of techniques to quantitatively describe the vegetation at Oratia. From a preliminary survey and aerial photographs the five vegetation sectors shown in Fig. 4 were demarkated. The differences in species composition and structure between these areas can be largely attributed to their different histories. 153 The sectors marked A and D were cleared prior to 1904, and grassed with "rat-tail" grass {Sporobolus africanus). Cut stumps (probably kauri) in a decayed condition immediately north of Stream A have diameters ranging from 75 to 150 cm. This area has been left undisturbed since 1904 apart from occasional small fires. In 1898, the area marked sector B was clothed by tall Leptospermum. In this year much of the canopy was removed and sold for firewood. The undergrowth, which included kauri seedlings less than 3 m high, was left relatively untouched. Detailed information about area C is not available but based on comparisons with sectors A and B it has obviously been disturbed, in part, during the last 75—150 years. An old survey map shows that it was once included in a fenced area. For each sector, Shirley (1968) described the species composition of the different strata (canopy, understorey, shrub and ground layers) and illustrated the structure with black and white photographs. A quadrat survey employing 21 quadrats each of 84 m2 was used to assess the floristic relationships between the different sectors. Canopy species were recorded in four size classes. These results can be summarised as follows: Area A: A relatively high density of Leptospermum ericoides mainly in the seedling and saplings size classes. Both Agathis australis and Phyllocladus trichomanoides present with a relatively high density of seedlings only. Other species with high densities were Cyathea dealbata, Coprosma spathulata and Hedycarya arborea. Area B: Agathis australis abundant in all size classes and Phyllocladus trichomanoides present in all size classes. Podocarpus totara and Dacrydium cupressinum well represented in the tall pole and tree categories. Leptospermum ericoides present only as seedlings and saplings. Area C: Leptospermum ericoides mainly in the sapling and tall pole categories. Pseudopanax crassifolius present at low density and Phyllocladus trichomanoides and Dacrydium cupressinum present only as seedlings and saplings. There was a notable absence of Agathis australis in this sector. Area D: This area showed a relative scarcity of Agathis australis, Podocarpus totara, P. ferrugineus, Dacrydium cupressinurn, Knightia excelsa and Phyllocladus trichomanoides. These were replaced by Melicytus ramiflorus, Cyathea dealbata and Geniostoma ligustrifolium. Leptospermum ericoides had a high density in the tree size class only. The four regions can be ranked in terms of their disturbance and state of regeneration. Area C is the most recently disturbed and consists of young Leptospermum. Next comes Area D with late mature stages of Leptospermum. In Area A Leptospermum is still present but kauri seedlings are becoming more abundant. Areas B and Bl are the least

154 disturbed with the presence of mature Agathis australis and Phyllocladus trichomanoides. From these studies Shirley (1968) derived a species list of 77 species made up as follows: ferns and fern allies, 18 species in 9 families; Gymnosperms, 7 species in 2 families; monocots, 10 species in 6 families; dicots, 42 species in 13 families. Subsequently this list has been added to in various field trip reports in the Newsletter of the Auckland Botanical Society. In 1964 M. Barr noted the presence of the tiny ferns Schizaea dichotoma and Lindsaea trichomanoides. The following trees, otherwise rare in the Auckland area, were also added: Eugenia maire, Dacrydium kirkii and Dacrydium colensoi. In 1968 L. W. Butler reported the orchids Pterotylis trullifolia var. rubella and P. trullifolia var. alobula, and the superficially similar trees Mida salicifolia and Olea (= Nestegis) lanceolata. More recently (1982) the authors found a single small specimen of matai, Podocarpus spicatus on the slopes of Ridge B. These notes bring the recorded species number to 88, but this may not be complete.

ANAWHATA

The property at Anawhata comprises 7 ha, and extends from a narrow road frontage, to the cliff tops overlooking Fisherman's Rock at the north end of White's Beach, on the west coast of Auckland (Fig. 5). (Grid reference: Ql 1/398737; NZMS 260 Sheet Qll Waitakere, 1st Edition, 1979). In 1966 the owners of 17 acres (7 ha) of land bordering White's Beach, near Anawhata on the western side of the Waitakeres, including Professor L. H. Briggs, Dr J. C. Andrews, Mr W. E. La Roche, Dr Lucy Cranwell-Smith and Mr P. R. Parr, bequeathed this property to the University, together with the "University Hut" (Anawhata Hut) without constraint except that both land and building should, if possible, be preserved in their state at the time of gifting. The coastal forest and scrub, unfortunately considerably damaged by fire in 1949, has been of less scientific interest than the other bush reserves, but the hut has proved an excellent base for maritime research on West Coast marine flora and fauna.

HISTORY The Anawhata Valley was heavily milled from 1867 to the 1920s. Kauri logs from the Anawhata Stream were driven downstream to timber mills on the coast and the timber transported by tramway to the Manukau Harbour for distribution (Diamond and Hayward 1979). The remains of these activities are still visible to some extent and they have been documented by Hayward (1978). A wooden holding dam and three stringer dams were constructed in the Anawhata Stream during the 155 Fig. 5. Map of the Anawhata reserve. 1910s. The mill at began operations in 1906 but it was not until 1916 that the tramway was extended the 6 km from there to the Anawhata holding dam. Further operations included a mill situated at the head of the Anawhata Stream operated by a Mr Burgeson. A short tramway, less than 400 m, was employed to lift his timber with the aid of rope and a petrol winch, out of the valley and up to the Anawhata Road where there was a loading ramp for road vehicles (Lowe 1973). The closure of this mill around 1930 saw the end of an era of timber felling in the Waitakere Ranges. CLIMATE There is no meteorological station close to Anawhata. The nearest stations are inland in the Waitakeres (Woodhill, Kumeu or Oratia) and are at different altitudes. GEOLOGY AND SOILS Hayward (1976) has classified the rocks of the Anawhata region as

156 belonging to the Lower Miocene Waitakere Subgroup. They are composed of andesitic fragmental beds with numerous intrusive dykes and minor interbedded flows. There is strong evidence that these rocks were derived from volcanic eruptive centres close at hand. The deep weathering of these volcanic deposits has produced clayey soils which are prone to slipping. The threat of erosion is increased by the steep topography. Holocene sand dunes are present between White's beach and the cliffs behind.

TOPOGRAPHY AND VEGETATION Along the west coast the powerful waves of the Tasman Sea have eroded seacliffs hundreds of metres in height with their bases often protected by beach and wind-blown sands. The recent submergence of the has been well documented (Searle 1944) and the drowned mouths of some of the larger streams, such as Piha stream, provide evidence for this on the Waitakere coastline. The Anawhata property is bisected by a steep ridge. On either side of this the land slopes away to cliffs, one facing south towards White's Beach and the other north-west overlooking Paikea Bay. The highest point on the property is about 180 m above sea level. A foot track from the road gives precarious access to White's Beach. This stretch of coastline is reputed to have been a particularly fine example of coastal vegetation. Especially large and beautiful pohutukawas once lined the steep walls of White's Beach. At the north end of the beach the great trees overhung a wall of elegant andesite columns below which a narrow track led onto Fisherman's Rock. Here the vegetation was massed flax {Phormium tenax), cabbage trees {Cordyline australis), toetoe (Cortaderia splendens), puriri (Vitex lucens), and even a few handsome tawapou (Planchonella novo-zelandica). All over the headland grew clumps of renga lily (Arthropodium cirratum) and rauhuia, the dainty white-flowered true flax (Linum monogynum) (Cranwell 1981). In November 1949, however, all of this was destroyed. Fire swept around the northern and eastern sides of the box-like bay, turning it into an inferno. The small cottage, which is now the University hut, and some patches of bush to the south were saved. Most of the property now supports regenerating coastal vegetation dominated by windswept manuka (Leptospermum scoparium). Similar stunted coastal communities are described by Esler and Astridge (1974).

LEIGH

While separately administered by the Leigh Property Committee, the Leigh Farm, acquired by the University in 1972, contains two small

157 patches of native bush which have been studied by University groups from time to time and through which a botanical walk, complete with numbered sites and an illustrated brochure by Professor and Mrs J. E. Morton, has been established with the help of student workers under the surveillance of staff of the Marine Laboratory. Maps of the area are given in Gordon and Ballantine (1976); their fig. 7 shows the bush clad gully of Matheson Stream, the location of some large kauri trees and the nature trail. (Grid reference: N29/316305; NZMS 1, Sheet 29, Pakiri).

CLIMATE Climatic data for Leigh Laboratory are available from an on-site meteorological station (No. A64282). The climate of the region, based on data for 1967—1975, has been thoroughly discussed in Gordon and Ballantine (1976). The rainfall (c. l 222 mm per annum) is lower than at the other reserves discussed here, and temperature extremes are buffered by close proximity to the sea.

GEOLOGY AND SOILS A full account of the geology, including many references to original geological descriptions, and accompanied by a diagram of a geological section from the Leigh Laboratory to the Mokohinau Islands is presented by Gordon and Ballantine (1976). There are two major groups of rocks in the area, with minor occurrences of a third. These are the Mesozoic Waipapa Group, (locally comprising strongly indurated grey and green greywacke sandstones); the Lower Miocene Waitemata Group (alternating unfossiliferous feldspathic sandstones, ripple- marked mudstones and carbonaceous shales, containing interbedded Mahurangi grits and basal conglomerates); and the Ti Point basalts (Hopgood 1961).

TOPOGRAPHY AND VEGETATION General features of the coastal topography and its present vegetation are reviewed by Gordon and Ballantine (1976) and what follows relates mainly to the valley of Matheson Stream, where the detailed work reported in the second paper in this series was carried out. Most of the original coastal pohutukawa forest has been destroyed, but modified patches remain on Goat Island, in the valley of Matheson Stream, and elsewhere on the steep coastal slopes. The vegetation of Goat Island has been described by Morton (1974) and Esler (1975) and the cliff communities by Cornforth (1975). The cliff top walk passes through coastal forest with a canopy of puriri, taraire, karaka (Corynocarpus laevigatus) and kohekohe (Dysoxylum spectabile). Tawa (Beilschmiedia tawa) is also present, with some representatives of its broad-leaved form (Wright 1982). The understorey includes mapou, mahoe, lacebark (Hoheria populnea), nikau 158 and cabbage trees. Epiphytes (e. g. Astelia solandri) are abundant on the puriri and kohekohe trees. At the seaward ends of the gullies, in which this forest occurs, pohutukawa, kawakawa (Macropiper excelsum) and houpara (Pseudopanax lessonii) are common. Further inland hybrids between this latter species and lancewood (P. crassifolius) are frequent. At the inland end of the gullies, such as the one through which Matheson Stream flows, are remnants of podocarp broadleaf forest, which must formerly have been the most widespread vegetation type. A few medium sized kauri trees (the largest was 105 cm in diameter at breast height in 1980), and a ricker stand, remain in Matheson's Bush. The marginal areas of this patch are highly modified with abundant shrubby coprosmas (C rhamnoides and C. areolata) and a canopy of manuka and kanuka 4 to 6 m tall. Seedlings of rimu (Dacrydium cupressium), totara (Podocarpus totara), kahikatea and tanekaha are abundant beneath this canopy. These are accompanied by shrubby five finger (Neopanax arboreum), lancewood, kohuhu (Pittosporum tenuifolium) and hangehange (Geniostomum ligustrifolium). The silver tree fern (Cyathea dealbata) is abundant, and mamaku (C. medullaris) occurs in the damper hollows. The original high species diversity of this forest is implied by the list for the walkway given in Morton and Morton (1980), which comprises 78 species, including 37 dicotyledons in 23 families and 14 pteridophytes. Matheson's Bush is situated in a narrow valley running out to the coast some 2 km east of the Marine Laboratory at Leigh. It covers an area of approximately 4 ha and is elongated from north-east to south• west along the Matheson Stream valley. Within the gully the slopes are moderate to steep. The bush patch is surrounded on three sides by pasture (described in Gordon and Ballantine 1976). In the past stock have had free access, but the lower part of the gully on the University property is now fenced. Its vegetation has been briefly described by Gordon and Ballantine (1976). A sketch map of the vegetation, prepared in 1980, is available on request from the authors. Matheson's Bush is much more highly modified than either the Swanson or Huapai sites, having been logged, burned and grazed. Although a few larger kauri and puriris appear to have escaped relatively unscathed, there is no doubt that the majority of trees on the site have regenerated since fires in the area about the turn of the century. Fire scars on the large kauri were tentatively dated to 1904 and none of the five kauri trees cored in the ricker stand in 1980, including two of the largest (32 and 37 cm diameter), pre-dated this. The intense and recent disturbance to the stand is reflected in its reduced floristic diversity compared to Huapai and Swanson. This is especially noticeable in the upper parts of the area, where kanuka scrub and a small kauri ricker abut onto pasture. Although seedlings of many

159 species are present here, relatively few tree species achieved a DBH greater than 10 cm. As at Swanson and Huapai maximum floristic diversity occurs on the intermediate slopes. The valley bottom is dominated by puriri, tarairi and some large old kanukas. There are two large kahikateas. Proximity to the coast is indicated by the presence of pohutukawa and Pseudopanax lessonii.

ACKNOWLEDGEMENTS

A preliminary account of the University reserves was written by Professor J. A. Rattenbury and has been freely used in the introductory sections of this paper. Professor Rattenbury has been a member of the University "off-campus reserves committee" since its formation, and he has been vigilant to protect and extend the reserves, to utilise them for teaching and to encourage others to do the same. The background of literature was researched while one of us (GMT) was employed under the Temporary Employment Programme of the Department of Labour, and supervised by Dr N. D. Mitchell. Dr Mitchell is thanked for assistance with some of the field work on which the vegetation descriptions are based. The manuscript was typed by Miss Sharyn York.

REFERENCES

Anon. 1971: The Council, University of Auckland Tour of University Reserves December 13, 1971. Unpublished handbook. 5 p. Bieleski, R. L. 1955: Experimental studies on factors affecting growth and distribution of kauri Agathis australis (Salisb. ) M. Sc, thesis, University of New Zealand. 187 p. Bucha, J. 1975: Nitrogen fixation in forest Utter and associated studies. M. Sc, thesis, University of Auckland. 160 p. Chambers, T. C. 1952a: Bryophyte and lichen ecology at Swanson. B. Sc. (Ill B) project, University of Auckland. 34 p. Chambers, T. C. 1952b: Bryophyte and lichen ecology at Swanson. Tane 5: 18-26. Clunie, N. M. U. 1967: The synecology of a lowland forest in North Auckland - a quantitative approach. B. Sc. (Ill B) project, University of Auckland. 29 p. Cornforth, R. C. D. 1975: A biogeographical classification of coastal environments with particular reference to Pakiri-Leigh-Omaha. M. Sc, thesis, University of Auckland. 97 p. Cox, S. H. 1881: The geology of the Rodney and Marsden counties. Report of the Geological Exploration during 1879—80: 13-39. Cranwell, L. M. 1981: "The Botany of Auckland". An Auckland Institute and War Memorial Museum Handbook. 155 p. Diamond, J. T. and Hayward, B. W. 1979: "The Maori History and legends of the Waitakere Ranges". The Lodestar Press, Auckland. 49 p. Esler, A. E. 1975: Inner Islands of the Hauraki Gulf: Goat Island, Leigh. Report to Hauraki Gulf Maritime Park Board, lip. Esler, A. E. & Astridge, S. J. 1974: Tea tree (Leptospermum) communities of the Waitakere Range, Auckland, New Zealand. New Zealand Journal of Botany 12 (A): 485-501. Gordon, D. P. & Ballantine, W. J. 1976: Cape Rodney to Okakari Point marine reserve. Review of knowledge and bibliography to December 1976. Tane 22: (supplement): 146 p. Hayward, B. W. 1976: Lower Miocene stratigraphy and structure of the Waitakere Ranges and the Waitakere Group (new). New Zealand Journal of Geology and Geophysics 19(6): 871-895. Hayward, B. W. 1978: "Historic archaeological sites of the Waitakere Ranges, West Auckland, New Zealand". Auckland Regional Authority. 73 p.

160 Hochstetter, F. von. 1864: Geologie von Neu-Seeland. Reise der Novara 1 (1): Cotta, Stuttgart. Hopgood, A. M. 1961: The geology of The Cape Rodney-Kawau district, Auckland. New Zealand Journal of Geology and Geophysics 4: 205-230. Kidson, E. 1950: The elements of New Zealand's climate. In "New Zealand Weather and Climate". New Zealand Geographical Society Miscellaneous Publications No. 1. Lowe, D. 1973: "The Piha Tramway". Lodestar Press, Auckland. 32 p. McKinnon, A. D. 1930: Vegetation survey of the Auckland Forest School Reserve, Swanson and of the Huia, Nihotapu and Waitakere catchment areas. B. For. Sc. thesis, University of New Zealand. Mirams, R. V. 1951: A study of some of the factors concerned in the natural regeneration of the kauri Agathis australis. Ph. D. thesis, University of Auckland. 181 p. Mirams, R. V. 1957: Aspects of the natural regeneration of the kauri (Agathis australis Salisb. ) Transactions of the Royal Society of New Zealand 84 (4): 661-680. Mohan, E. J. 1980: Physiological ecology of germination and early seedling establishment of Leptospermum scoparium (J. R. et C Forst. ) in the Waitakere Ranges, Auckland, New Zealand. M. Sc, thesis, University of Auckland. 136 p. Morton, J. E. 1974: Habitat: Goat Island. New Zealand Nature Heritage 3 (37): 1 037-1 040. Morton, J. & Morton, P. 1980: "Guide to Leigh Walkway". Leigh Marine Laboratory, University of Auckland. 14 p. New Zealand Soil Bureau. 1968: Soils of New Zealand Part 1. New Zealand Soil Bureau Bulletin 26(1). Government Printer, Wellington. Ogden, J. 1983: The scientific reserves of Auckland University II. Quantitative vegetation studies. Tane 29: Parris, B. S.; Dickson, E. M. & Rae, W. J. 1970: The establishment of permanent quadrats in pastureland at Swanson. Tane 16: 31-44. Searle, E. J. 1944: Geology of the Southern Waitakere Hills region west of Auckland City. Transactions of the Royal Society of New Zealand 74 (1): 49-70. Shirley, J. W. 1968: The Oratia Reserve. B. Sc. (Ill B) project, University of Auckland. 41 p. Silvester, W. B. 1963: An artificial key to the vascular plants common in the Swanson area of the Waitakere Ranges. Tane 9: 105-124. Trevarthen, C. B. 1952: The historical background to the vegetation of the University property at Swanson and its present condition. Tane 5: 12-17. West, C. J. 1980: Aspects of regeneration on Tiritiri Matangi Island. M. Sc, thesis, University of Auckland. 173 p. Wright, A. E. 1982: A taxonomic revision of Beilschmiedia Nees (Lauraceae) in New Zealand. M. Sc, thesis, University of Auckland. 129 p.

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