SOME TUSSOCK-SHRUBLAND ASSOCIATIONS IN TONGARIRO NATIONAL PARK

by David Royce Trenery 113 Carlisle Road, Browns Bay, Auckland.

The tussock-shrublands near the Chateau, at the Tongariro National Park were surveyed. The red tussock, Chionchloa rubra, and the moss, Racomitrium lanuginosum were found throughout the surveyed area. Distinct alpine mire and dry rocky plant associations were found. Within parts of the alpine mire, the wire rush, Empodisma minus tended to exclude several .

INTRODUCTION

The Tongariro National Park covers some 75 250 hectares (Wises guide 1979). Of this approximately 10 040 ha is tussock- shrubland (Atkinson 1981). Tussock-shrubland has a shrub cover in excess of the area covered by any other kind of plant and contains 20% or more cover of tussock forming plants (Atkinson 1981). In July 1985 tussock-shrubland in the Tongariro National Park around the Chateau was investigated with the aim of assessing some of the plant associations within this area.

STUDY SITES

The Chateau is situated in the north-east sector of the Tongariro National Park at 62° 19'N 27° 29'E, the vegetation in the immediate vicinity consists of tussock-shrublands, mountain beech forest and patches of grassland and sedgeland (Fig. 1, modified from Atkinson 1981). Six study sites within the tussock-shrubland were surveyed (Fig. 1). Sites A and B were situated in an alpine mire at an altitude between 1150 and 1200 m; sites C, D and E on a slope between 1300 and 1350 m. Site C was in places extremely wet; site E was dry and rocky; while site F was on fairly level ground next to the Chateau and between 1150 and 1200 m in altitude.

METHODS

At each site a tape was laid out and a 0.15 m2 quadrat placed every 5 metres along the tape. The presence of all higher plants, including lycopod species within the quadrat was noted, conspicuous mosses and a

TANE 31, 1985-86 155 s^ow^ «» Chateau, Tongariro National Park lichen i.e., Dicranoloma, Racomitrium and Cladia sp. were also noted.

156 Cluster analysis was carried out to determine species and quadrat affinities. Cluster analysis The details of the cluster analysis are as follows: two similarity matrices were created from the frequency data, containing similarities between quadrats and species. The similarity values used in these matrices were Jacard's coefficient (Chatfield & Collins 1983): Jacard's coefficient = a/a+b+c where for two quadrats 'a' = the number of species the quadrats have in common, 'b' = the number of species found in quadrat one but not quadrat two and 'c' is the number of species found in quadrat two but not in one. The formula for species is similar, for quadrat read species and species read quadrat. Cluster analysis using the single link clustering algorithm (see Orloci and Kenkel 1984, for details) was then carried out on both of these matrices. RESULTS

Hybrids between the Dracophyllum species were classified as the parent they resembled most. The cluster analysis revealed three distinct assemblages of plants (Fig. 2) and a large number of plants with no close affinity with any other

PLANT SPECIES

Fig. 2. Dendrogram showing the affinities between plant species.

157 species. The three plant assemblages were as follows:

1. red tussock, Chionochloa rubra; Cyathodes empetrifolia; inaka, ; wire rush, Empodisma minus; bog umbrella-fern, Gleichenia dicarpa and the moss, Racomitrium lanuginosum.

2. Anisotome aromatica; a mountain daisy, Celmisia incana; Cyathodes fraseri; Epacris alpina; Gaultheria colensoi; club moss, Lycopodium fastigiatum; Ourisia vulcanica; a little mountain-heath, Pentachondra pumila and Wahlenbergia sp. 3. An unidentified club moss; bog pine, Halocarpus bidwillii; Pimelea buxifolia; mountain toatoa, Phyllocladus aspleniifolius (P. alpinus).

From the cluster analysis quadrats can be divided up into three assemblages and a number of quadrats with no close relationship with more than two other quadrats (Fig. 3). The three quadrat assemblages were as follows:

QUADRAT

2

0 >

Fig. 3. Dendogram showing the affinities between quadrats. The letters refer to the site each quadrat comes from.

1. a group of 26 quadrats from sites A, B and C. 2. a group of 7 quadrats from site E. 3. a group of 4 quadrats from site D. The species belonging to plant assemblage one, and these species only, were all present in 33% or more of the quadrats belonging to quadrat assemblage one. All these species were frequent elsewhere in the alpine mire and many were frequent at other sites (Table 1). The members of plant assemblage two were all present in 33% or more of the quadrats belonging to quadrat assemblage two, and were often

158 Table 1. Percentage frequency of plant species for various quadrat groupings. Location Species QA1 QA2 QA3 AO BO CO DO K Lichens Cladia sp. 17 40 20 Mosses Dicranoloma sp. 8 33 20 33 20 Racomitrium lanuginosum 65 71 100 66 40 22 50 66 60 Lycopods Lycopodium fastigiatum 57 13 33 20 Lycopodium sp. 7 Ferns Gleichenia dicarpa 100 14 100 93 100 78 83 Gymnosperms Dacrydium cupressinum 17 57 50 13 33 50 Halocarpus bidwillii 20 Phyllocladus aspleniifolius 13 (P. alpinus) Grasses Chionochloa rubra 61 71 100 66 20 56 17 33 56 small unidentified tussock 8 57 50 20 17 33 40 unidentified sp. 8 17 Sedges Carpha alpina 4 Gahnia procera 13 11 unidentified sp. 4 13 33 Rushes Empodisma minus 96 33 22 33 Anisotome aromatica 71 7 44 33 Brachyglottis bidwillii 14 Calluna vulgaris Cassinia vauvilliersii 29 40 33 Celmisia gracilenta 4 29 27 20 33 33 66 C. incana 17 86 100 56 83 66 40 Coprosma cheesemanii 7 C. parviflora 11 C. propinqua 22 50 20 Coprosma sp.l 8 7 Coprosma sp.2 11 Coprosma sp.3 22 Cyathodes empetrifolia 52 33 20 17 C fraseri 43 4 33 Dracophyllum longifolium 35 33 60 56 17 D. recurvum 13 43 100 7 33 83 100 40 D. subulatum 29 50 47 20 22 17 Epacris alpina 43 17 33 40 Gaultheria colensoi 86 13 22 33 80 Hebe venustula 8 47 60 33 Hebe tetragona 14 75 33 33 Helichrysum sp. 4 60 Leptospermum scoparium 22 17 60 Leucogenes leontopodium 20 33 Myrsine nummularia 29 17 Ourisia vulcanica 100 Pentachondra pumila 13 57 40 40 Pimelea buxifolia 7 17 P. prostrata 50 14 22 83 33 20 Wahlenbergia sp. 57 33 unidentified sp.l 7 unidentified sp.2 14 unidentified sp.3 4 14 unidentified sp 4 33 60 Key QA1 = Quadrat assemblage 1 AO = Those quadrats at site A other than those in QA1. BO = Those quadrats at site B other than those in QA1. CO = Those quadrats al site C other than those in QA1. DO - Those quadrats at site D other than those in QA3. EO = Those quadrats at site E other than those in QA2.. F = All quadrats at site F.

159 frequent in other areas. Plant assemblage three consisted of a group of uncommon plants found in those quadrats at site A which did not belong to quadrat assemblage one. Plants which occurred in all four quadrats of quadrat assemblage three were as follows: Chionchloa, Gleichenia and Racomitrium which belonged to plant assemblage one; Celmisia incana belonging to plant assemblage two; and Dracophyllum recurvum which was frequent at many sites but occurred most frequently in quadrat assemblage three. Empodisma was found only at sites A, B, and C. In quadrat assemblage one Empodisma was extremely frequent, present in 96% of the quadrats (Table 1) and species diversity was low (Fig.4). Elsewhere

0 A 1 1 1 1 1 1 1 1 1 1 QAl QA2 QA3 AO BO CO DO EO F QAl*

QUADRAT GROUPING * excluding those species belonging to Plant Association 3.

Fig. 4. Species diversity for each group of quadrats. For key see Table 1. at sites A, B, or C Empodisma was less frequent, present in 22-40% of quadrats and diversity higher, significantly so at site A. The high diversity in the quadrats at site A other than those belonging to quadrat assemblage one was due in part to the members of plant assemblage three occurring here, although species diversity would still be high in these quadrats without these species (Fig. 4). Cassina sp. and the heather, Calluna vulgaris, were frequent, 40 and 60% respectively, in the site B quadrats other than those belonging to quadrat assemblage one. Cassina was also present in quadrat assemb• lage two, otherwise these two species were absent from other areas (Table 1). In those quadrats at site C not belonging to quadrat assemblage one, all members of plant association one occur with moderate frequency except Cyathodes spp. which were absent. Some members of plant assemblage two were also common.

160 The flora at site F was similar to that of quadrat assemblage two in that no species were found at site F which were not also found in quadrat assemblage two. However, the flora at site F lacked several of the species found in quadrat assemblage two, noticably Anisotome, Ourisia, Penta- condra and Wahlenbergia, resulting in this site having significantly lower diversity than quadrat assemblage two and the other quadrats at E (Fig. 4).

DISCUSSION

Within the tussock-shrublands surveyed, Chionochloa and Racomitrium were frequent throughout, and two distinct plant associations were found at the ends of a moisture gradient. In the wet conditions of the alpine mire and site C, a plant association was found comprising of Chionochloa, Cyathodes empetrifolia, Dracophyllum longifolium, Empo• disma, Gleichenia and Racomitrium. Associated with the dryer rocky conditions found at site E was a plant association consisting of Anisotome, Celmisia incana, Cyathodes fraseri, Epacris, Gaultheria, Lycopodium, Ourisia and Pentacondra. Intermediate stages between the alpine mire and rocky plant associations were found at site D and parts of site C, while site F seems to be a low diversity version of the dry rocky plant association. Within the alpine mire plant diversity was significantly higher where Empodisma was less frequent. Empodisma tended to form dense swards and in this manner probably excluded many species. Halocarpus, Pimelea buxifolia and Phyllocladus were among the species excluded by Empodisma. Environmental differences within the alpine mire may have restricted Calluna and Cassina to parts of site B or it may be that these two species had yet to colonize site A. Most of the variety found in the composition of the tussock-shrublands surveyed in this study may be attributed to differences in soil moisture and plant interactions.

ACKNOWLEDGEMENTS I would like to thank Susan Asplin for her assistance with the field work and identification of the plants, and for her company which made the project enjoyable. REFERENCES

Atkinson, I.A.E. 1981: Vegetation map of the Tongariro National Park, , New Zealand. Scale 1:50 000. DSIR, Wellington. 1 map + notes (27p). Chatfield, C. & Collins, A.J. 1983: Introduction to multivariate analysis. Chapman and Hall, New York. 246p. Orloci, L. & Kenkel N.C. 1984: 'Introduction to data analysis'. Prepublication copy. 'Wises New Zealand guide'. 1979: Wises, Auckland. 518p.

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