TANE 22, 1976 N O R T H C A P E Q U A D R A T S 1975

by A . E . Wright

Department of Geology, University of Auckland, Private Bag, Auckland

S U M M A R Y Permanent quadrats established at North Cape in December 1965 have

been re-surveyed, and vegetation maps and the estimated percentage cover of plants within the quadrats are presented. Further notes on the location of the quadrats are included, together with a list of items required for permanent marking of the quadrats. Using the results o f all surveys to date, the vegetation succession from bare ground in the quadrat area at North Cape is outlined and discussed.

I N T R O D U C T I O N During the Auckland University Field Club's "after-degree" camp to the

Far North of New Zealand in November 1975, several day trips were made to the North Cape Scenic Reserve for the purpose of re-examining the permanent vegetation quadrats set up by a member of the Club in 1965. Five quadrats exist: four in randomly selected "plateau scrub" (Wheeler 1963) of which two remain in their natural state (one fenced), and two have been cleared (one fenced); and a fifth quadrat in an area o f "hinterland scrub" (Wheeler 1963) which had been burnt over just before the initial work on the quadrats in 1965.

Gravatt (1966) reported the establishment of the quadrats, and gave vegetation maps for the two uncleared quadrats, and a brief description of the vegetation of the fifth quadrat in the hinterland scrub. A year later, Johnstone (1967) reported on his re-examination o f the quadrats, and gave vegetation maps of the two cleared quadrats and a further description of the hinterland scrub quadrat which he named the "rush quadrat" due to the then dominance of Schoenus brevifolius. In 1969 the quadrats were surveyed once again; Rae (1970) gave vegetation maps for the cleared and uncleared quadrats, a further description of the rush quadrat, and introduced the estimation of percentage cover of species within all quadrats to provide "a quantitative basis for comparison with future investigations".

Thus the present paper includes the second analysis of percentage cover, the third set o f vegetation maps and descriptions of the plateau scrub quadrats and the fourth description of the rush quadrat. In addition, further description of the location of the quadrats is given, and a list of the requirements for adequate permanent marking of the quadrats is appended.

L O C A T I O N O F Q U A D R A T S Gravatt (1966) provides a Location Map of the quadrats which is rather

inaccurate, and of little assistance in the field. Several name changes have occurred and future workers are advised to consult N Z M S 1 Sheet N l & N2 North Cape (2nd Edi t ion 1970) which gives current place names and a more accurate plot o f the access road and quarry. Extraction of serpentine has

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obviously continued until a short time ago and is likely to resume in the near future. Due to the increase in the size of the quarry, simply bearing due north from it may become insufficient information for location of the quadrats. The present writer found the following procedure the easiest method of locating the rush quadrat, from which the other quadrats could be seen. Proceed along the access road to the north o f the quarry until looking south, Te Totipo Head ( N l & N2/496463) is in line with the highest point o f the ridge ( N l & N2/499538) forming the eastern side of the valley in which the quarry occurs. By walking due north from that point on the road, the rush quadrat will be found on the top of the first slight ridge. The remaining four quadrats are situated in a group approximately 100 metres due north of the rush quadrat, and the steel waratahs of the uncleared, fenced quadrat are clearly visible above the vegetation (Fig. 1). A further 50 metres or so north is the top of the Surville Cliffs. The two fenced quadrats are obvious and side by side. The uncleared, unfenced quadrat is situated 3m southeast of the cleared, fenced quadrat and its pegs may become obscured by further growth of the vegetation. The cleared, unfenced quadrat is located approximately 6m to the southwest o f the other three quadrats in the plateau scrub.

M E T H O D S The vegetation in the four plateau scrub quadrats was mapped after the

methods of Gravatt (1966), Johnstone (1967) and Rae (1970), except that plants in the cleared quadrats were mapped as points where their main stem entered the ground. Three of the quadrats were marked by manuka pegs, some of which had rotted and fallen over; and measurements of all dimensions still marked by original pegs showed that conversion to metric measurement on the scale of 30 centimetres to one foot gave no greater inaccuracy than the actual size in feet and inches as compared with the proposed size at establishment. In the case of one quadrat, described as 4 feet by 4 feet, two dimensions (one length, one breadth) were measured at exactly 120cm. Similarly, a test estimation of percentage cover using a six inch grid gave negligible differences to the results from the use of a 15cm grid. Therefore any pegs replaced were sited at the converted metric distance.

Thus the fenced and unfenced uncleared quadrats were mapped as 1.8m square (formerly 6 feet square), and the percentage cover estimated from points taken every 15cm along lines 30cm apart, giving 91 points (as before). The fenced and unfenced cleared quadrats (4 feet square) were mapped as 1.2m square, and the percentage cover estimated from points taken every 15cm along lines 15cm apart, giving 81 points as before. The rush quadrat (12 feet square) was taken as 3.6m square and the percentage cover estimated from points every 30cm along lines 30cm apart, giving 169 points as before. During estimation of percentage cover, species present in the quadrat but not 'hit ' were also noted.

The north-south line was found to lie obliquely across all four plateau scrub quadrats, not parallel to one o f their sides as has been shown in previous vegetation maps. In addition, orange painted pegs denoting the reference corner were found on the eastern corner in all cases, not the northern corner for the uncleared quadrats as stated by Johnstone (1967).

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Future workers are strongly advised to take suitable materials for the construction of sampling grids over the quadrats, which can also be used in mapping the vegetation.

U N C L E A R E D Q U A D R A T S Unfenced (Control) Quadrat (Fig. 1 foreground)

Marked by four 40cm high galvanised pipes, the eastern one painted orange (reference corner, marked X on vegetation maps). The vegetation map for the quadrat is presented in Fig. 2. The area covered by the larger shrubs is outlined, but it is important to note that the entire remaining area (with the exception of the small bare patch in the southern corner) was covered by a more

Fig, 1. Uncleared quadrats looking north towards top of SUIT ill e Cliffs. Peg in foreground marks southern comer of uncleared, unfenced quadrat. Four waratahs in middle distance are part of a fence around the uncleared, fenced quadrat. Leaning pole at far right is part of the remains of die fence around the cleared fenced quadrat

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or less dense mat of manuka (Leptospermum scoparium). Groundcover plants and seedlings were plotted beneath the shrub cover. The estimation of percentage cover together with other species present is given in Table 2. Manuka, Cassinia amoena, Hebe ligustrifolia and catsear (Hypochaeris radicata) were all flowering and the sun orchid (Thelymitra longifolia) and Pomaderris prunifolia var. edgerleyi had set seed. Fenced Quadrat (Fig. 1)

Marked by four 10cm manuka pegs set inside a wire-netting fence with steel waratahs in each corner. The wire-netting was extremely frail and had rusted completely through in places, and the manuka pegs were in poor condition. The eastern peg showed the remains of orange paint. The fence was repaired as much as possible, using the fallen wire-netting which had previously covered the top of the quadrat. The vegetation map is given as Fig. 3 and the estimated percentage cover appears in Table 2. Once again, manuka plants cover the remaining quadrat area not already designated in Fig. 3. Cassytha paniculata occurred throughout the quadrat but was most dense in the largest Cassinia amoena and Hebe ligustrifolium bushes. Manuka, C. amoena and H. ligustrifolium were all flowering, while Cyathodes fraseri, C. parviflora and Pomaderris prunifolia var. edgerleyi had set fruit.

Table 1. Abbreviations used in Figs. 1-4. Where appropriate, these follow Rae (1970).

Abbreviation Species

A Aira caryophyllea Ca Cassinia amoena

Cladia aggregata CI Cladonia sp.

Cyathodes parviflora Cy Cyathodes fraseri F Dead Phormium tenax H Hypochaeris radicata He Haloragis cartilaginea He Hebe ligustrifolia Hp Haloragis procumbens L Lepidosperma laterale La Lobelia anceps

Leptospermum scoparium M Morelotia affinis N Notodanthonia pilosa Pi Pimelea prostrata

Pomaderris prunifolia var. edgerleyi Pt Pteridium aquilinum var. esculentum T Thelymitra longifolia

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C L E A R E D Q U A D R A T S Unfenced (Control) Quadrat (Fig. 4)

Marked by four 10cm manuka pegs in poor condition, the eastern one showing traces of orange paint (i.e. reference corner). Plant cover is still sparse in both cleared quadrats, and the vegetation maps show each plant at the point where the main stem enters the ground. A l l plants in the cleared quadrats were depauperate and stunted. The vegetation map of the cleared, unfenced quadrat is given as Fig. 5 and the estimation of percentage cover appears in Table 2. Weathering of the soil has left large numbers of limonite concretions and nodules ranging up to 2cm in size. Over much of the quadrat, these completely cover the ground, and they were observed to move considerably in heavy rain. These movements would greatly reduce the chances of seedling establishment, and could partially explain the lack of young seedlings in the quadrat. Pomaderris prunifolia var. edgerleyi was the most common species present, the two largest

Fig, 4. Looking north across cleared unfenced quadrat. Peg in foreground approx. 10cm tall.

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plants having main stems just over 1cm in diameter. The majority of plants were under 8cm high; one manuka plant was flowering even though it was only 3cm high and had seven leaves. The one Cassinia amoena bush in the quadrat appeared healthy; however, several clumps of bracken (Pteridium aquilinum var. esculentum) appeared to have died completely. Fenced quadrat

Marked by four manuka pegs, and roughly fenced. Although limonite nodules and concentrations were less numerous than in the unfenced, cleared quadrat, considerable erosion of the soil had occurred, as evidenced by the 5-8cm downcutting of soil between the older established plants. One strand of Cassytha paniculata lay across the quadrat, although it is not shown on the vegetation map (Fig. 6). The greatest floristic difference between the cleared quadrats was the common occurrence of Notodanthonia and Morelotia in the fenced quadrat, neither of which were represented in the unfenced quadrat.

Percentage cover

Uncleared Geared

Unfenced Fenced Unfenced Fenced

Bare ground t 2.20 67.85 67.95 Aira caryophyllea 1.25 Cassinia amoena 18.65 17.60 1.25 2.45 Cassytha paniculata t t t Cladia aggregata t Cladonia sp. t t t t Cyathodes fraseri t 3.30 3.70 Cyathodes parviflora 1.10 1.10 t Haloragis cartilaginea 1.25 Haloragis procumbens 1.10 1.25 Hebe ligustrifolia 11.00 11.00 Hypochaeris radicata 5.50 1.10 t t Lepidosperma laterale 5.50 2.20 1.25 Leptospermum scoparium 40.65 42.80 t 1.25 Lobelia anceps t Morelotia affinis 2.20 2.20 1.25 Notodanthonia pilosa t 3.70 Pimelea prostrata t 1.10 2.45 3.70 Pomaderris prunifolia var. edgerleyi 6.60 6.60 17.20 13.50 Pteridium aquilinum var. esculentum 7.70 8.80 4.95 2.45 Thelymitra longifolia t t 1.25

Table 2. Estimated percentage cover of species in cleared and uncleared quadrats in the Plateau scrub, f indicates species present but not hit.

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R U S H Q U A D R A T This quadrat is marked by four 40cm high galvanised pipes. In line with

earlier surveys, the vegetation was not mapped; however, the percentage cover of plants was estimated and appears in Table 3. The manuka bushes have increased in height to 40-50cm, Schoenus brevifolius to a maximum of 60cm, Pomaderris kumeraho to 10-20cm and P. prunifolia var. edgerleyi to 5-10cm high with a more pronounced spreading habit.

Percentage Cover

Leptospermum scoparium 41.25 Schoenus brevifolius 29.00 Cyathodes fraseri 5.30 Pomaderris prunifolia var. edgerleyi 2.35 Pomaderris kumeraho 0.60 Pteridium aquilinum var. esculentum 0.60 Drosera auriculata t Bare ground 21.90

Table 3. Estimated percentage cover of species found in the 'rush' quadrat, f denotes species present but not hit.

DISCUSSION Over the six years since the quadrats were last surveyed a great number of

significant changes have occurred. For the first time, the importance of lichens has been noted. A n epigean species of Cladonia occurs in all four quadrats in the plateau scrub, and appears to play an important primary colonising role in the cleared quadrats and other bare areas on the North Cape Peninsula. The movement towards greater maturity of plant communities is clearly reflected in changes in percentage cover, and to a lesser extent in their composition.

The decrease in adventive species probably reflects a combination o f increasing maturity and lack of interference by grazing animals (of which no signs were seen in the plateau scrub area). Catsear (Hypochaeris radicata) was still present in all quadrats, although the plants were extremely stunted and unhealthy, the only other adventive present being three tiny plants o f silvery hair grass (Aira caryophyllea) in the cleared, fenced quadrat. None of the adventives previously recorded for the quadrats, e.g. scarlet pimpernel (Anagallis arvensis), cudweed (Gnaphalium sp.), tarweed (Parentucellia viscosa) and Viburnum sp., were seen anywhere near the quadrats, although they occurred elsewhere in the Scenic Reserve in generally small numbers.

One correction in identification was required: four clumps in three quadrats labelled as Lepidosperma laterale by Rae (1970) were actually Morelotia affinis, although Lepidosperma laterale was still the most common monocot in the plateau quadrats.

The uncleared quadrats showed large increases in the size and cover o f Cassinia amoena, Hebe ligustrifolium, Pimelea prostrata, Cyathodes parviflora

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Ca Pm

•Pm

Pt

• Ls

.Pt

H Pt-

P , - P m

Pm tJ Pm ' M

™ . P m • Pm

Pm

Pm

X

Pm Hp •Ls

Pm

Hp Ls

Ls

Pm

X

Fig, 5. Vegetation map of unfenced cleared quadrat in November 1975. Length of one side 1.2m. See Table 1 for explanation of abbreviations.

Hc.^-~-xN

Ca •Cp

X

\ Fig. 6. Vegetation map of fenced cleared quadrat in November 1975. Length of one side 1.2m. See Table 1 for explanation of abbreviations.

and Morelotia affinis, and a corresponding decrease in the percentage cover of manuka. Cassinia amoena and Hebe ligustrifolium bushes up to 50cm high had become visually dominant over the lower (20-30cm) manuka, and were dense enough to stop the growth of catsear beneath most of them. Lepidosperma, although most clumps had increased in size, did not appear to be able to compete with the shrubs as well as Morelotia affinis, which was taller and had far thicker growth.

Variations exist in the species lists for the uncleared quadrats, each having two species not present in the other. The unfenced quadrat includes Haloragis

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procumbens and Thelymitra longifolia while the fenced quadrat contains Lobelia anceps and one clump of the lichen Cladia aggregata. The flax (Phormium tenax) plant mapped by Rae in the fenced quadrat is still present, although dead, and a new plant is growing just outside the quadrat boundary, slightly east o f the northern corner.

In analysing changes in the cleared quadrats, the almost complete lack of correlation between the 1969 and 1975 vegetation maps became very quickly apparent. It should be noted that the X ' s denoting the reference corners in figs. 3 & 4 (Rae 1970) and the two figures on p i 4 4 of Johnstone (1967) should appear in the eastern or top right-hand corners of the diagrams. Even with this amendment there is a low correlation between the maps. In an attempt to assess the stability of each species present in the quadrats, a transparency of the present vegetation maps was laid over the 1969 maps, and a score of the number of correlations for each species was made. These were then expressed as percentages of the total number of individuals o f each species present in 1975 (see Table 4).

Unfenced Fenced

Cassinia amoena * 12.5 Cyathodes fraseri 33.3 t Haloragis procumbens 40.0 * Leptospermum scoparium 40.0 * Pimelea prostrata * 33.3 Pomaderris prunifolia var. edgerleyi 31.3 34.6 Pteridium aquilinum var. esculentum 11.1 0 Thelymitra longifolia 66.6 100.0

Table 4. The number of plants growing in the same position within the cleared quadrats in 1969 and 1975 expressed as a percentage of the total number of individuals of each species present in 1975. f indicates species not present, * indicates very small number of plants.

This shows that the sun orchid Thelymitra was the most stable species within the quadrats in the last 6 years. Approximately 35% of the Pomaderris prunifolia var. edgerleyi plants present in 1973 were located in the same position as plants of that species in 1969. Manuka, Cyathodes fraseri and Haloragis procumbens also show relatively high correlations for the quadrats in which they are common.

The adventive grass Poa annua, reported to be one of the main species present in the cleared quadrats in 1967 was entirely absent in 1975; and had been replaced by danthonia (Notodanthonia pilosa). This native grass was actually a numerical co-dominant in the fenced quadrat, and was extremely widespread throughout the plateau scrub, often forming small areas of pasture especially along the top of the Surville Cliffs. The possibility that the poa and danthonia are one and the same does exist, although a great reduction in numbers of poa occurred between 1967 and 1969, perhaps heralding the

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eventual demise of the species in the plateau scrub. This change could then be taken as a further indication of the movement towards maturity of the vegetation, through reduction of the adventive content (partly brought about by the decrease in interference by grazing animals).

As with the uncleared quadrats, each of the cleared quadrats contained species not found in the other. The cleared, fenced plot contained Aira cayophyllea, Cyathodes fraseri and Haloragis procumbens not present in the fenced quadrat; the latter having Cassytha, Cyathodes parviflora, Haloragis cartilaginea, Lepidosperma and Morelotia which did not occur in the unfenced quadrat.

In analysing changes in the rush quadrat, the percentage cover in 1969 (Rae 1970 — Table 2) was compared with corresponding figures for the present survey (Table 3). Manuka appears to have doubled its percentage cover over the interval, with a corresponding decrease in cover by the rush, Schoenus brevifolius. Some narrowing of the flora appears to have occurred with the disappearance of Poa annua, Pomaderris phylicifolia var. ericifolia, Cassinia amoena, Lepidosperma, Cassytha and Parentucellia; and no new species were found. The other species found in both surveys show essentially similar results. The apparent increase in bare ground may be misleading, as many points recorded as bare lay amidst dead stems of Schoenus.

C O N C L U S I O N S From the work on the plateau scrub quadrats to date, the following

succession from bare ground appears to be occurring: 1. Bare ground is colonised by epigean lichens (Cladonia sp.), adventive weeds and prostrate or low growing natives - dominantly Pomaderris prunifolia var. edgerleyi, bracken, Cyathodes fraseri and Haloragis procumbens. 2. Over a period of five years or so, a decrease in adventive weed species with a corresponding diversification of the native flora occurs. Cudweed, scarlet pimpernel, tarweed and Poa annua decline and disappear, and secondary shrub species such as Cassinia amoena and manuka appear, along with Thelymitra and Lepidosperma. Bracken, Pomaderris prunifolia var. edgerleyi and Haloragis remain dominant, although all plants are still covering only 20% of the ground. 3. After another five years, plant cover rises to 30%, although the ground is still visually very bare. Dominant species remain the same, and Cassinia, Pimelea, Cyathodes fraseri and danthonia become more prominent. (This represents the present state of the cleared quadrats). 4. After an undemonstrated time interval, probably approximately 20 years in the sheltered situation of the quadrats, the development of a more or less complete cover of manuka appears to occur, which provides shelter for the establishment o f Hebe ligustrifolia and Cyathodes parviflora. This approximates the state of the uncleared quadrats o f 10 years ago. Many of the primary colonising species remain, e.g. bracken and Pomaderris, together with ground-cover plants such as Cyathodes fraseri and Haloragis procumbens. 5. A further 10 years growth sees Cassinia plants double in size and Hebe seedlings develop into shrubs with a 30-50cm diameter. Although manuka is still dominant in terms of percentage cover, it is generally below 30cm in height

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whereas Cassinia and Hebe bushes approach 50cm. 6. Further diversification occurs with the establishment of flax, the renga li ly (Arthropodium cirratum) and Morelotia affinis. A t this stage, depauperate catsear plants are the only adventives remaining. 7. For the future, one would predict increases in the percentage cover of Cassinia and Hebe as they become co-dominants in the plateau scrub. Sub-dominants will probably include flax, Cyathodes parviflora, Pimelea prostrata and bracken with a decrease in primary colonisers such as Pomaderris and manuka.

Within the rush quadrat, it is clear that the vegetation is developing into the manuka dominated hinterland scrub of Wheeler (1963), as suggested by Johnstone (1967). Manuka now provides almost 50% of the cover, and has increased in height to 50cm.

A C K N O W L E D G E M E N T I would like to thank Associate-Professor J . A . Rattenbury for critically

reading the manuscript.

REFERENCES Gravatt, D.J. 1966: Establishment of Permanent Quadrats in Plateau Scrub at North Cape.

Tane 12: 87-91. Johnstone, LM. 1967: A Report on the Permanent Quadrats at North Cape. Tane 13:

143-146. Rae, W.J. 1970: North Cape Quadrats 1969. Tane 16: 53-60. Wheeler, J.M. 1963: The Vegetation of the North Cape Area. Tane 9: 63-83.

A P P E N D I X Further Requirements for Permanent Marking of Quadrats

At present, all quadrats are inadequately marked. The rush quadrat requires one 1.5m orange painted length of galvanised pipe for the reference comer, this length so that it wil l stand sufficiently high above the vegetation to be seen. The present 60cm eastern pipe can then be re-used in one of the plateau scrub quadrats.

The uncleared, fenced quadrat requires four 60cm lengths of pipe (one orange painted) to mark the corners o f the quadrat itself. The waratah corner posts o f the fence are quite satisfactory, however the wire-netting should be replaced as soon as possible, preferably with stronger, "Hurricane" type netting. (8m required, plus tying wire). The uncleared unfenced quadrat is in the same state as the rush quadrat and requires one 1.5m orange painted pipe for the eastern corner.

The cleared, fenced quadrat requires a complete new fence, including four waratah standards and four 60cm pipes (one orange) for the corners of the quadrat itself. The cleared, unfenced quadrat requires one 1.5m orange painted pipe, and three 60cm pipes. Summary of requirements: 3 x 1.5m orange painted lengths, galv. pipe

9 x 60cm lengths pipe, 2 painted orange 4 x waratah standards 2 x 8m lengths of Hurricane netting Tying wire and tools.

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