R. B. a Plant Communities of the Steepland Conifer- Broadleaved Hardwood Forests of Central Westland, South Island, New Zealand

Sonderdrucke aus der Albert-Ludwigs-Universität Freiburg

ALBERT REIF R. B. ALLEN

Plant Communities of the Steepland Conifer- Broadleaved Hardwood Forests of Central Westland, South Island, New Zealand

Originalbeitrag erschienen in: Phytocoenologia 16 (1988), S. 145 - 224 Phytocoenologia 16 (2) 145-224 Stuttgart-Braunschweig, May 18, 1988

Plant communities of the steepland conifer-broadleaved hardwood forests of central Westland, South Island, New Zealand by A. REIF, Bayreuth, and R. B. ALLEN, Christchurch with 8 photos, 20 figures and 5 tables

Abstract. This paper presents a phytosociological classification of the conifer-broadleaved hardwood forests in central Westland, South Island, New Zealand. The analysis was made using the BRAUN-BLANQUET approach. Because this approach has rarely been applied in New Zealand, syntaxa were not named using BRAUN-BLANQUET nomenclature. The following community groups and communities were distinguished: 1. The Melicytus ramiflorus community group contained shrubland and low statured forest (c. 4-12 m tall) on disturbed sites up to c. 750 m altitude: — The Melicytus ramiflorus — Carpodetus serratus community (A) was frequently found on lower faces, on terraces, in gullies, and in canopy gaps. Soils were recent to weakly developed and contained fine earth. Most relevēs were from schist and greywacke areas. — The Coriaria arborea community (B) was sampled in a few schist areas adjacent to streams. 2. The Prumnopitys ferruginea community group contained 3 communities: — The Dacrycarpus dacrydioides community (C) was c. 20-30 m tall forest. It occurred locally on poorly drained sites, usually terraces, up to c. 300 m a.s.l. (above sea level). — The Dacrydium cupressinum community (D) was c. 15-30 m tall forest. It was found on sites up to c. 600 m a.s.l., on stable ridges, upper faces, and terraces. This community was most frequent in granite areas. — The Prumnopitys ferruginea — Coprosma lucida community (E) was c. 15-25 m tall forest. It was found frequently in schist and greywacke areas up to c. 750 m, mainly on ridges and upper slopes of faces; it was infrequent in granite areas. 3. The Hoheria glabrata community group contained 2 communities: — The Hoheria glabrata community (F) (canopy c. 5-10 m tall) occurred on disturbed sites, often in gullies and on lower faces. It was found above c. 600 m. It was infrequent in granite areas. — The Plagianthus betulinus community (G) was a low statured (10-12 m tall) forest. It was found locally on silty alluvial river terraces subject to cold air drainage. 4. The Libocedrus bidwillii community group contained 2 communities: — The Libocedrus bidwillii — Myrsine divaricata community (H) was c. 10-25 m tall forest. It was found frequently between c. 650 and 850 m. — The Dracophyllum traversii community (I) was stunted forest and shrubland (canopy between c. 5 and 15 m). It was encountered frequently between c. 850 and 1200 m, mainly on stable sites (ridges and upper faces). 5. The Halocarpus biformis community group contained the — Halocarpus biformis — Gahnia procera community (J) and was mostly stunted forest and shrubland (canopy c. 1-8 m). It was found locally on stable sites with developed soils. 6. The Hebe salicifolia community group contained 2 communities occurring at all altitudes. Both communities were seral vegetation often establishing on primary sites:

10 Phytocoenologia 16 0340-269X/88/0016-0145 $ 20.00 0 1988 Gebrüder Borntraeger, D-1000 Berlin • D-7000 Stuttgart 146 A. Reif R.B. Allen

— The Raoulia tenuicaulis community (K) was an open community with low ground cover dominated by small herbs. Most frequently it was found on river terraces. — The Hebe salicifolia community (L) was dominated by herbs and small shrubs (up to c. 2 m tall). It was found mainly on rocky sites in schist and greywacke areas. Using 28 species groups, further partitions could be made to 43 "sub-units", including subdivisions, types and subtypes. The floristic relationships of the community types were transformed into a hierarchical arrangement. Variation in species composition was dominantly related to altitude, and disturbance resulting in soil differences. Different frequencies of disturbance can be related to landscape stability and topographic position: In schist areas, disturbances of soil and vegetation were frequent, and low-statured seral communities and tall forests frequently were found in a small-scale vegetation pattern. In granite areas, the canopy is more uniform, with few areas of seral vegetation. These large-scale differences in landscape stability and vegetation can be related to different intensities of canopy mortality. Mortality of canopy trees is higher in schist areas than in granite areas. This may be a consequence of differential browse pressure by introduced brush-tailed possums (Trichosurus vulpecula Kerr.).

1. Introduction

1.1. General introduction The New Zealand indigenous forests now cover c. 23% of the country's 270000 km2 area (P. WARDLE et al. 1983). When the first Maori migrants arrived about A.D. 950 (DUFF 1950), forest covered most of New Zealand (MASTERS et al. 1957). During the next 900 years, the indigenous forests were reduced to perhaps half their original area (CAMERON 1962). The Maori population initiated fires which destroyed large areas of forest, mainly in the drier regions (CUMBERLAND 1962; HOLLOWAY 1954). Over the period 1850 to 1950 European settlers removed about half of the remaining forests (CAMERON 1962). The remaining indigenous forests are found mainly in mountainous areas. There is currently little direct anthropogenic influence within these forests. However, most have been, and con- tinue to be, modified by introduced browsing animals (P. WARDLE et al. 1983; J. WARDLE 1984). The indigenous forests fall into two broad categories; beech and conifer-broadleaved hardwood forests. These are composed of four major physiognomic ele- ments; beeches (Nothofagus species), broadleaved hardwoods (hardwoods other than beeches), kauril (Agathis australis) and conifers other than kauri (COCKAYNE 1928; McKELVEY NICHOLLS 1957). Beech forest dominated by pure beech in the canopy constitutes 46 % of the forested area, and 22 % is made up of forest dominated by mixtures of beeches, conifers, and broadleaved hardwood species (J. WARDLE 1984). The remaining 32 % of forest is dominated by conifer and broadleaved hardwood species. Conifer-broadleaved hardwood forests usually occur in areas with high rainfall (up to 12 000 mm per year) and mild climates (P. WARDLE et al. 1983). These areas tend to be in western and northern parts of the country (NEW ZEA- LAND FOREST SERVICE 1984). These forests usually have a more complex struc-

Nomenclature of generic and common species names in Appendix 1 Steepland conifer-broadleaved hardwood forests of central Westland 147 ture than beech forests, and have affinities with the structure of tropical rainforest, often containing lianes and epiphytic plants (DANSEREAU 1964). By calling the forests "subtropical rainforest", COCKAYNE (1928) recognised these affinities. As latitude increases, the number of species making up the forests seems to decrease (P. WARDLE 1975,1980c). Canopy tree species and epiphytes in particular decrease in numbers. Species composition also varies with altitude. The conifer-broadleaved hardwood forests of central Westland represent the general pattern. In this region the dominant canopy hardwood species include southern rata (Metrosideros umbellata), kamahi (Weinmannia racemosa), and Quintinia acutifolia. At lower altitudes (< 600 m a.s.l.) these species are associated with the conifers miro (Prumnopitys ferruginea) and rimu (Dacrydium cupressinum; FRANKLIN 1968). Dacrycarpus dacrydioides and Prumnopitys taxifolia are prominent at lower altitudes on fertile, often alluvial, sites. At higher altitudes (> 800 m) these hardwood species occur with the conifers Libocedrus bidwillii and Halls totara (Podocarpus hallii) (COCKAYNE 1928; P. WARDLE 1977). At altitudes above c. 1000 m, conifer- broadleaved hardwood forest gives way to a wide belt of subalpine shrubland dominated by Dracophyllum spp., Halocarpus spp. and the composites (Senecio spp., Olearia spp.), before grading into tussock grassland dominated by Chio- nochloa spp. (EVANS 1970; BURROWS 1977 b; P. WARDLE 1977). Within any altitudinal band, variations in species composition reflect different environmental factors, such as geological substrate (J. WARDLE 1974), geomorphic processes (P. WARDLE 1977, 1980a), and variation in soil development (CUTLER 1960; P. WARDLE 1977). All these factors are interrelated. In central Westland, forest patterns reflect site history, and often cannot be related in an obvious way to existing environmental conditions (P. WARDLE 1964). The removal of forests by glaciation and the subsequent slow immigration by beech have been used to explain the absence of beech and dominance of faster migrating conifer-broadleaved hardwood forest species (COCKAYNE 1928; WIL- LETT 1950). On a local scale factors such as high natural erosion rates (CUTLER 1962), high rainfall intensities and strong winds result in frequent disturbance. Relationships have been drawn between disturbance and the maintenance of canopy species (e.g., HUTCHINSON 1928; P. WARDLE 1980a). Some authors have related discontinuous size (age) distributions of species to recent climatic change (HOLLOWAY 1954; P. WARDLE 1978 a), but these may also be significant- ly influenced by disturbances such as windthrow and landslides (e.g., MOLLOY 1969a, 1969b; VEBLEN STEWART 1982 b). Overlying these natural patterns is the impact of recently (c. 100 yrs) introduced browsing animals. Classification of forests is a means of simplifying the spatial complexities of vegetation and its environmental and successional relationships (GAUCH 1982). Different approaches have emphasized floristic, structural, or physiognomic attributes (WHITTAKER 1973; MUELLER-DOMBOIS ELLENBERG 1974; HAVEL 1980). For New Zealand forests, DANSEREAU (1964) questioned the useful- ness of floristically based approaches because of the broad ecological amplitude of many species, and considered that structural attributes should be emphasized. A number of authors have classified forest vegetation in central West- land (bibliography: ORWIN 1974). Broad classifications were based on dominat- 148 A. Reif R.B. Allen ing species, stand structure, climate, and topography (COCKAYNE 1928), or they emphasized timber species volume and gave little detail on montane forests (MASTERS et al. 1957; McKELVEY 1985). Other, more detailed studies are available for a number of smaller areas, but different methods of community analysis were used and the results are not comparable throughout the whole central West- land. Eight "associations", three of them dominated by beech, were defined by J. WARDLE HAYWARD (1970) in the upper Taramakau catchment. The vegetation of the Hokitika catchment was described by JAMES et al. (1973; unpubl. rep.), and vegetation of the Hohonu Range by J. WARDLE (1974). In these studies, vegetation was correlated to site factors like altitude and physiography and to stand structure. The plant communities found in Westland National Park were classified by species composition, whith emphasis on dominating species, stand structure and landforms, by P. WARDLE (1977). Sampling a diverse range of site conditions throughout the central Westland steepland conifer-broadleaved hardwood forests allowed a more detailed description of floristic, environmental, and successional relationships of the vegetation than has been possible before. The phytosociological method chosen for this study was that of BRAUN-BLANQUET, which is commonly used in Europe (MUELLER-DOMBOIS ELLENBERG 1974; van der MAAREL 1975; GAUCH 1982). This approach has rarely been used in New Zealand forests. Three main ideas can be traced in the BRAuN-BLANQUET approach (van der MAAREL 1975): a) Plant communities are recognised by their floristic composition. It is assumed that all species can be used to express relationships of communities to one another and to site conditions better than any other community characteristic. b) Some species are more sensitive expressions of a particular relationship than others. The approach uses those species whose ecological relationships make them the most effective indicators. These diagnostic species comprise character- species, differential-species, and constant companions. Together they form a characterizing species combination. c) Character-species and differential-species are used to organise communities into a hierarchical classification in which the association is the basic unit. This hierarchy is invaluable for the understanding of community relationships. The frequency of occurrence of diagnostic species is expressed as "fidelity". Character-species have high fidelity when they occur mostly or exclusively in only one vegetation community, but have medium fidelity when their frequency and/or ground cover in one community is higher than in others. Differential species always occur in more than one community (low fidelity). Thus frequencies can be used to characterise and delineate communities. The result is a classification which is hierarchical, integrated and comparable (van der MAAREL 1975).

1.2. Study area Conifer-broadleaved hardwood forests dominate in central Westland between c. 42° 50 S and c. 43° 40 S, where Nothofagus spp. are absent (Fig. 1). Selected localities (Fig. 2) were sampled in the steepland forests between the lowland flood plains and moraines in the west, and the upper altitudinal limit of forest on the western slopes of the Southern Alps.

^ ^ti` 77 O ^p, ^s 0 ^..^ 0 Ca, el p 00 .7 `< n P 7.;Wrtn ^ ^ ^ Grey River nP ^ • ß. . Y n a N w °n. ^^ ,...,^^n .1–, Taramakau River 0 ^ ^ P +v,v, • ^ � ^ ^ Ft •^ ^ 0 vi^ n rt C o Hokitika River � n =-fD W ,.. ^ n n ^ a S

ii;^ P Wanganui River b"ô 0 9 o ^ ^ O. P n z y ^ Whataroa River ^"1 cmcnz...� ^ o 5 ara ^ W ^. ^--►oaa ^• lD •0 `-‹ v, ^ d b Waiho River "NG woa ^ ^ ^ o P• p,. ^ rD pa n tr p. ^ a • w y N Cook River ^ — cfQ. y Ili nD np nD Karon arua River o °►^ 0 y 9 kn. wO b Farmland, alineP and other non-forested ^ ^ N ^.0 W E 0 Paris River areas nP ^ ^... 0 ora..• • 9a P? ► • nv,n) n ^ nD 0 r7 ~ Po ß, V1 S Lowland conifer and conifer-broadleaf hardwood r ^ •^+ 5 oa^,w ^" forest, with abundant conifers (Dacr Ydrum ro ^ cupressinum, Dacr car us dacr dioides etc.) • rtxro rt et R ^ Y P Y ^ CD P ] P �P o Fr r° r4 Lowland hardwood and uplandP conifer-broad leaf 0 0 > r• ^ N,.., hardwood forest (with PrumnoPY it s ferruginea,9 aôn^" b • P • PodocarP us hallii, Libocedrus bidwillii ) et ^ ^ et o►^ ^^ o ./.1y mimiimu Beech forest dominated byY Nothofagus9 menziesii N.fusca cD t3 p W et ^ôG^ and N.solandri var. cliffortioides,associated with conifers P rt N rt a and hardwoods at lower altitudes P.0^.,, °s,,,. v, `^ 0 50km 00o rt ^wrD ^K ^âro p, Fig.s 1. Forests of the studyY area, Localities sampledp were largelygY within the lowland hardwood and uplandP conifer- broadleaved hardwood forests (After: New Zealand Forest Service 1977). 150 A. Reif R.B. Allen

South Island N.Z.

1 Hohonu Range 2 Te Kinga 3 Granite Hill 4 Camp Creek 5 Otira 6 Wainihinihi River 7 Kokatahi River 8 Harihari - Wanganui River 9 Bonar Range 10 Fox Glacier 11 Karangarua River! Copland River 12 Hunt Hill 13 Douglas Range

Glacier and al permanent snow field --- Ridge top

0 10 20 30 40 km w^

Fig. 2. Localities samples within central Westland (1 to 13). Steepland conifer-broadleaved hardwood forests of central Westland 151 rua catchment and Douglas Range to the south (Fig. 3). The Otira locality (Fig. 2) is underlaid by strongly indurated Mesozoic greywacke and argillite (NEW ZEALAND GEOLOGICAL SURVEY 1975). West of the Alpine Fault paleozoic biotite granite occurs at Granite Hill, Te Kinga and Hohonu to the north, at Bonar Range in the central part of the study area, and parts of Hunt Hill (near Paringa) to the south (NEW ZEALAND GEOLOGICAL SURVEY 1975). The single most important tectonic feature of Westland is the Alpine Fault, which runs approximately 600 km in a SW—NE direction (SOONS 1982). It results from long-term increasing convergence between the Australian and Pacific plates, and during the last few million years, rapid uplift, with substantial variations in rate, has occurred east of the Alpine Fault (BULL COPPER 1986). A total in excess of 15 000 m uplift during the last few million years is not unlike- ly in some regions (OLOUGHLY PEARCE 1982). In the later part of the Pleistocene glaciation large areas of the West Coast were covered by glaciers. In the north, coastal and lowland areas were not covered, but, in the south the ice limits extended well beyond the present coast line (SUGGATE 1965; PILLANS et al. 1982; SOONS 1982). It often is assumed that a few islands of granite (e.g., Bald Hill) were not glaciated and provided refugia for vegetation in the south. In the last (Otira) glaciation forest may have persisted on interfluve areas on steep slopes and in the north on the coastal lowlands (SOONS 1982). The glaviers have fluctuated in length and volume in post glacial times (P. WARDLE 1973; BURROWS GREENLAND 1979) and associated vegetation changes are still occurring in parts of the area sampled, e. g., in the Fox catchment (P. WARDLE 1973; P. WARDLE 1980a). Glaciation has transported much eroded material out of the mountain valleys. Glacial moraines are large and extensive in lowland areas and have been modified by fluvial action (SOONS 1982). Some plant communities at Oemoroa and Lake Gaulth in the central parts of the study area and parts of Hunt Hill in the south occur on Quaternary glacial outwash gravel and till (NEW ZEALAND GEOLOGICAL SURVEY 1975). In lowland areas, particularly along the courses of major rivers, alluvial terraces are found. In montane areas, the landscape is the result of fluvial modification of former- ly glaciated valleys. The forested slopes are steep, often greater than 30 degrees, and are subject to landslides (debris slides or debris avalanches). Slope erosion and mass wasting appear to attain maximum development in the steep gorge sections of the main valleys east of the Alpine Fault, which are in high-grade schists, and the zone of maximum instability coincides roughly with the zone of maximum precipitation (O'LOUGHLIN & PEARCE 1982). Estimates of sediment yields in these areas are high, from approximately 1000 to 10 000 m3/km2/y (OLOUGHLIN PEARCE 1982). ADAMS (1980) has suggested that uplift and erosion rates are broadly in balance.

1.2.2. Soils Landform processes determine the distribution and pattern of soil types (e.g., P. WARDLE 1977; SMITH LEE 1984; HARRISON 1985a). Patterns and rates of soil development on alluvium are variable (STEVENS 1968; SMITH LEE 1984). In many places downcutting streams result in recent soils on steepened ö ta. a. < CD ö •-cs Taramakau River cr ro et> r 0- Hokitika River

rtz a • Po GA

CL. Wanganui River 0 cn CD

P-1 CD .

cr) (1) Alluvial, moraine

o 0 Cook River Granite (g ) (1) s Karangarua River z cr Biotite Zone, garnet to oligoclo.se Paringa River 7z1 15* Zone quartzo - feldspathic schist, crcl locally gneissic Is) 0 Zrx Chlorite Zone quartzo- feldspathic ,0 semi-schist and schist (s ) 00 n. tJ1 r, Greywacke ( gw )

z Pb) 50km \CD Others ( Phyllite, Hornfels,etc) ( o ) CO ••••• • CD cr co, rD g Fig. 3. Geologiy of central Westland and adjacent areas. Most study localities were in the schist zone adjacent to the Alpine Fault and a a ro co, cn in granite areas to the west. Steepland conifer-broadleaved hardwood forests of central Westland 153 rate of soil developement is also controlled by site characteristics such as the very high rainfall, soil drainage, and vegetation (e.g., BURNS 1931; BLOOMFIELD 1954; P. WARDLE 1977; SMITH LEE 1984). Soils of montane areas have been described only broadly and are mapped as upland high country and steepland podzolised yellow-brown earths and podzols (NEW ZEALAND SOIL BUREAU 1969). Soils are typically skeletal on unstable steeper slopes, with increasing development on lesser slopes and often podzol and gley podzol formation on gentle slopes and ridge crests. At lower altitudes, alluvial fans and terraces are mapped as lowland yellow-brown earths (NEw ZEA- LAND SOIL BUREAU 1969). The type of landform processes and the rate at which they operate vary throughout the study region. This is reflected in the soils. In the Fox catchment, glacial action is more recent than in other areas sampled, resulting in an unstable landscape with extensive recent soils. In contrast, the soils in granite areas are often more developed, partly because they were not covered by ice, being north- west of the Alpine Fault, and partly because the rate of geomorphic processes in granite areas is typically slower.

1.2.3. Climate

The description of climate is mainly based on the work of HESSEL (1982) and GRIFFITHS McSAVENEY (1982, 1983a, 1983 b). Generally, the climate is humid to superhumid, with mild temperatures at lower altitudes (LUKE 1968). Climatic gradients are strong, both vertically and from east to west, but are less marked from north to south (0LoUGHLIN PEARCE 1982). Throughout the region, annual rainfalls are high and ranges of mean monthly temperatures are small. However, for much of the area climatic information is sparse. The Southern Alps deflect the prevailing westerly air stream, which is forced to ascend. This often causes heavy and prolonged rain. Dry spells are rare. Pre- cipitation in the montane areas ranges from 6000 to more than 10 000 mm/year. Some of this variability is attributed to altitude and distance from principal ridge crests at right angles to the prevailing wind direction. Rainfall intensities can be high, for instance, intensities of 680 mm in 24 hours have a return period of 2.3 years in parts of the Hokitika catchment and 1800 mm in 3 days has been recorded in Westland National Park (GREYMOUTH EVENING STAR 1982). Snow falls frequently in the higher altitude forest and may remain for periods of over a week, but at lower altitudes snow is infrequent and soon melts. In Westland, humidity is generally between 80 % and 90 %, and dry air periods are rare. At Otira (383 m a.s.l.), mean monthly temperatures range from 3.5 °C in winter to 18.8 °C in summer (NEW ZEALAND METEOROLOGICAL SURVEY 1974-1978). A lapse rate of 6 degrees C per 1000 m altitude can be used as an estimate of the change in montane regions.

1.2.4. Introduced browsing animals Species recently established in the forests of central Westland include the mar- supial brush-tailed possum (Trichosurus vulpecula Kerr.), and the ungulate spe- 154 A. Reif R.B. Allen cies red deer (Cervus elaphus L.), goat (Capra hircus L.), chamois (Rupicapra rupicapra L.) and Himalayan thar (Hemitragus jemlahicus Smith). Red deer and brush-tailed possums are the most widely distributed and it is generally considered that they have caused modification of these forests (WODZICKI 1950; HOLLO- WAY 1959; GIBB FLUX 1973; PRACY 1974). The impact of introduced animals has been described for a number of areas (e.g., CHAVASSE 1955 unpubl.; HOLOWAY 1959; J. WARDLE HAYWARD 1970; P. WARDLE 1977; COLEMAN et al. 1980). Brush-tailed possums are arboreal feeders and defoliate certain species and have been considered as responsible for extensive mortality of species such as Fuchsia excorticata, Metrosideros umbellata and Weinmannia racemosa. Exclosure studies have shown recovery of defoliated trees (COLEMAN et al. 1985). Whereas, red deer browse the forest understorey. VEBLEN STEWART (1982) have recently stressed the importance of other factors in explaining patterns usually attributed to animal effects. Brush-tailed possums were present in all areas sampled. Most liberations occurred between 1890 and 1930 (PRACY 1974). Little information is available on when parts of the various catchments were colonised. High densities have occurred in some areas, for example, the Kokatahi (BOERSMA 1974) and Fox catchments (PEKELHARING REYNOLDS 1983). An ordered progression through an eruptive oscillation has been interrupted in some areas by aerial poison opera- tions, removing up to 85 % of the animal population (PEKELHARING 1979). Variation in density of brush-tailed possums can also be related to site characteristics. Density in forest dominated by southern rata and kamahi was approximately twice than in beech forest (PEKELHARING 1979). In central Westland, greatest densities were usually found in higher altitude forests (PEKELHARING 1979), but high densities may also occur at lower altitudes in close proximity to agricultural grassland (COLEMAN et al. 1980). Red deer were present in most areas sampled. In south Westland they spread from liberations in west Otago, and in central Westland from liberations in Can- terbury and Westland (LOGAN HARRIS 1967). As a result of spread across the main divide from 1910 on, deer were soon well established in catchments such as the Taramakau (HARRISON 1967; CHALLIES 1974). From there they have spread into most of the forested area. In many areas red deer were in high numbers 20 years after their arrival (CHALLIES 1974), and browsing resulted in de- pletion of the forest understorey (e.g., HOLLOWAY 1959, J. WARDLE HAY- WARD 1970). Limited areas, including the Fox catchment (Fig. 2) in Westland National Park, are still largely free of deer (PEKELHARING REYNOLDS 1983). Hunting since the late 1960s, mainly from helicopter, has heavily reduced numbers (CHALLIES 1974).

2. Methods

The method used for data collection and analysis of vegetation was based on the approach of BRAUN-BLANQUET (1964), with minor modifications. Individual stands (relevēs) were sampled in localities throughout the steepland conifer- broadleaved hardwood forests of central Westland (Table 1) from October 1982 to December 1983. Steepland conifer-broadleaved hardwood forests of central Westland 155

Table 1. Selected localities, locality abbreviations and number of relevēs in each locality.

Study area Number of relevēs

Granite Hill 73 Te Kinga 45 Hohonu Range 66 Camp Creek 290 Taramakau — Wainihinihi 9 Otira 40 Kokatahi 75 Bonar Range 102 Hari Hari — Wanganui R. 125 Fox 172 Karangarua — Copland 51 Hunt Hill/Paringa 18 Douglas Range/Paringa 21

Total: 1087

2.1. Data collection Some localities were sampled intensively so that much of the variation in the vegetation was included (e. g., Camp Creek). Other less intensively sampled localities were included because of specific characteristics of the vegetation (Karangarua- Copland). This enhanced the variability sampled. Releves were located subjective- ly without preconceived bias (MUELLER-DOMBOIS ELLENBERG 1974). Rare or short lived communities were often sampled at a similar intensity to widespread or longer lived ones. Each relevē was a floristically homogeneous area considered larger than the minimal area (sensu MUELLER-DOMBOIS ELLENBERG 1974). The relevē boundaries were often defined by topography and the sample area was not of a regular shape. Typical areas sampled for the types of communities encountered were recent landslide surfaces and river terraces 25 m 2 ; seral gully vegetation 50 m2 ; tall forest 400 m2. Vascular species present were recorded in four tiers, generally based on phy- siognomy: I) Tree tier (T): Emergent trees, canopy trees and lianes in the main canopy (when not closely appressed to supporting stems). Where the upper forest tier was less than 6 metres a tree tier was not recorded. II) Sub-canopy tree and shrub tier (S): This included shrub, sub-canopy tree and liane species (not closely appressed to the supporting stem, e. g. Ripogo- num scandens) usually with heights between I and 6 m but sometimes up to 10 m. Where the canopy was less than 6 m tall, the S-tier formed the canopy. Where the vegetation was less than 1 m tall, a sub-canopy tree and shrub tier was not recorded. III) Ground tier (H): All herbaceous species and woody seedlings less than 1 m were recorded in this tier. Also included were species of fallen lianes and epiphytes. 156 A. Reif R.B. Allen

IV) Epiphytes (E): Included all species growing on living and dead trees (including fallen trees) where the roots did not penetrate organic or mineral soil. Lianes growing closely appressed to other plant stems (e. g. Metrosideros diffusa) were recorded as epiphytes, even though rooted in mineral soil. Spe- cies of epiphytic origin, but subsequently rooted in the soil, were recorded in one of the three other tiers. The mean height and total cover of the tree, sub-canopy/shrub, and ground tiers were visually estimated and recorded. The cover of individual species in each tier, except the epiphyte tier, was estimated using the scale of BRAUN- BLANQUET (1964), which is a combined estimation of abundance and cover. Plants with an epiphytic life form were recorded only as present. Profile diagrams of representative stands have been reproduced in the text. The width of the profiles is c. 1.5-2.0 m. All individuals in the tree and shrub tier are shown along with the dominant herbaceous species. The abbreviations for species names on profile diagrams are given in Appendix 1. The following site information was recorded: geological substrate; altitude; aspect; slope; physiography, in four classes (gully, terrace, face, ridge). General features of the sample area such as soil drainage, evidence of disturbance and ground cover were noted. Dead standing canopy trees on each relevē were noted for three species (see Appendix 2).

2.2. Analysis of data

The classification was initially based on a multi-linkage cluster analysis using a presence/absence coefficient for species and a group averaging strategy (ALLEN McLENNAN 1983). Species with a cover class of "R" (= rare; only one or two small plants) were not used. All relevēs could not be used in a single cluster analysis because the matrix was too large. A first approximation used the 172 relevēs from the Fox catchment and resulted in six major distinctive groups. Relevēs from the other areas were added into these six major groups manually. A cluster analysis was then made of each group containing 130 to 230 relevēs. Each group from the cluster analysis was used to construct a raw table (BRAUN- BLANQUET 1964; MUELLER-DOMBOIS ELLENBERG 1974, p. 179 ff.) in which the relevēs were arranged in a species by sample matrix. Species of intermediate constancy (occurring in 10-70 % of the relevēs) were used to rearrange the table so that the relevēs (table columns) and species (table rows) with similar distribution were grouped together. The result was six "differentiated tables" (sensu MUELLER-DOMBOIS ELLENBERG 1974). By combining and rearranging these differentiated tables a summarized frequency table was formed (Table 2). The summarized frequency table shows the species groups (table rows) and relevē groups (table columns). Some infrequently encountered species (2 %) were used to form species groups based on the literature, and will be indicated in the text. The species groups were used in any combination and at any level to delineate the relevē groups. Where tree species were only found in the ground tier and species they were usually associated with were absent, they were ignored in forming relevē groups (i.e., assumed ephemeral). All species not used in the classification Steepland conifer-broadleaved hardwood forests of central Westland 157 are listed at the bottom of Table 2 ("other species"). The frequency class of individual species in each relevē group is expressed in roman figures. The nomenclature for species groups and relevē groups is not complete in the sense of BRAUN-BLANQUET (MUELLER-DOMBOIS ELLENBERG 1974). Be- cause the distribution of species outside the area sampled could not be accounted for, character-species were not determined. Species groups are called differential- species groups and include both character- and differential-species in the sense of BRAUN-BLANQUET (c. f. ARCHER CUTLER 1983). Because of this, relevē groups were also not named by BRAUN-BLANQUET nomenclature. The relevē groups were arranged into a hierarchical community classification in descending order from community to subdivision to type to subtype. Several communities were grouped together to form community groups (see Fig. 4). A "pure" subdivision, type or subtype is indicated (Fig. 4) where a differential- species group did not delineate it form the next highest level. Otherwise, these levels were named using one or two differential-species. As an example, the Dacry- dium cupressinum community, part of the Prumnopitys ferruginea community group, was subdivided into pure, Melicytus ramiflorus-, and Phyllocladus asplenii folius subdivisions. Each subdivision could be partitioned again into two or more types (e. g., a Ripogonum scandens type, a Metrosideros diffusa fusa type and a pure type), each type into two or more subtypes, using the presence or absence of other differentiating species groups. The community is the basic unit and may be viewed as equivalent to the association in the sense of BRAUN-BLANQUET (1964). In naming the hierarchically arranged classification units, one or two differentiating and evident species (e. g., with high cover or stature) were used. Abbre- viations for the community types are given at the bottom of the summarized frequency table (Table 2). Differential-species groups were named after a species of high frequency within the group.

3. Results and discussion

Six community groups (Fig. 4) within the conifer-broadleaved hardwood forests of central Westland were distinguished by six species groups (Table 2). Each of these species groups had its main center of distribution within the community group it differentiated. The six community groups were hierarchical subdivided into communities, subdivisions, types, and subtypes using additional differential- species groups.

3.1. Characterization of plant community groups

The 28 differential-species groups used are listed in Table 2. Some of the species forming these groups are given in the community group characterization the first time a species group is encountered. The description is arranged from community groups of low altitude (subsections 3.1.1. and 3.1.2.) to higher altitude (subsections 3.1.3. and 3.1.4.) and then to community groups showing less relationship to altitude (subsections 3.1.5. and 3.1.6.). 158 A. Reif R.B. Allen

Olearia ilicifolia subdivision Fuchsia excorticata subdivision Dracophyllum traversii subd ivision LL. Carpodetus serratus subdivision

Pure type Pure subdivision [Ripogonum scandens type tLLJ Melicytus ramiflorus I Pure type subdivision I Ripogonum scandens type) Phyllocladus (Libocedrus bidwillii type( aspleniifolius subdivision Pure type (Pure type Pure subdivision (Ripogonum scandens type( O [Freycinettia baueriana t. [Pure type Melicytus ramiflorus subdivision (Ripogonum scandens type( [Freycinettia baueriana t. I

• g C LL d O L ^ E m L E LiO d O

Hoheria glabrata [Hebe salicifolia type subdivision Pure type 1 Metrosideros diffusa Hebe salicifolia type 1 subdivision I Pure type Ripogonum scandens [Hebe salicifolia type subdivision Pure type

0 c o► E u0 Steepland conifer-broadleaved hardwood forests of central Westland 15 9

Transition to tall forest (Pure type Pure subdivision (Blechnum discolor type I J Pure type Sr (Pure subtype Helichrysum bellidioides subdivision Blechnum discolor type Cortaderia richardii subtype v 0 ō c E >, Y .d 1.. ° 0 (X 4- 0 Empodisma minus subdivision Pure subdivision

Phyllocladus aspleniifolius subdivision ^ Pure subdivision Pure type Cyathaea colensoi subdivision Hoheria glabrata type

Pure subtype Phyllocladus asplenii- Pure type folius subdivision Prumnopitys ferruginen su btype

-^ Pure subtype Pure type E _ Prumnopitys ferruginea Cyathaea colensoi subtype subdivis ion Pure subtype Hoheria glabrata type Prumnopitys ferruginea subtype

aaJ ^

Within each community group the floristic relationships, site characteristics, structure, and successional patterns are considered. The data collected was not the most appropriate for an analysis of successional patterns, but are discussed in a preliminary way based on the forest tiers recorded and floristic relationships. Table 2. Summarized frequency y table of the conifer-broadleaved hardwood forests of central Westland, South Island, Newew Zealand. Zea and.

THE FREQUENCIES OF THE SPECIES IN THE COMMUNITY SUBUNITS ARE IN THE CLASSES: R = IN 1 TO 5 5 OF THE RELEVES; III = IN 41 TO 60 % OF THE RELEVES; I = IN 6 TO 20 5 OF THE RELEVES; IV = IN 61 TO 80 % OF THE RELEVES; II = IN 21 TO 40 5 OF THE RELEVES; V = IN 81 TO 100% OF THE RELEVES.

ABBREVIATION OF COMMUNITY TYPE Al A2 A3 A4 A5 A6 B1 Cl D1 D2 D3 D4 D5 D6 D7 D8 El E2 E3 E4 Fl F2 G1 G2 H1 H2 H3 H4 H5 H6 11 12 13 I4 J1 J2 K1 L1 L2 L3 L4 L5 L6

NUMBER OF RELEVES 72 7 26 16 14 23 8 14 9 60 12 12 25 15 15 22 54 64 10 48 16 24 7 11 32 7 70 16 30 11 29 20 11 71 15 25 19 23 56 29 20 6 14

CORIARIA ARBOREA, USED TO DISTINGUISH THE CORIARIA ARBOREA COMMUNITY 01): CORIARIA ARBOREA . R R ..

MELICYTUS RAMIFLORUS SPECIES GROUP, USED TO DISTINGUISH THE MELICYTUS RAMIFLORUS-CARPODETUS SERRATUS COMMUNITY GROUP (A, B):

CARPODETUS SERRATUS IV V V VVVV I II III1I IV . R III . . . II 1 I • • I . • . • • II IV IV I III . II SCHEFFLERA DIGITATA V V V V IV IV V II 1 11 II I IV III . . II . II . I . R . . . . . . . R R R 1 • I MELICYTUS RAMIFLORUS V V V V III II V IV II III I IV III . . . R . I . . . . . . . . . I I II . I ARISTOTELIA SERRATA II V I V III III V I 1 I I . I V R IV III I I . R . • • . . I III II I I . I COPROSMA RHAMN0IDES II II II I1 I1 I I III III III IV R I I1 1 III IV . R I III . 1 1 I . R . • . • • R I R . II • II PENNANTIA CORYMBOSA II I I IV I II R I R . V iI ...... R R . FUCHSIA EXCORTICATA I I I II il I R . R . 11 1 V . 1 1 . .I . . . I I I . RUBUS CISSOIDES I I III 11 I I . I I R . I I 1 . I R . I1 I .. R 1 . .. R I R R. I PITTOSPORUM EUGENIOIDES R . . . 1 I .R . . . R R . I . . I . . . . . . . ... R . . . I COPROSMA ROTUNDIFOLIA R . . III I . R I I ^ URTICA FEROX I III I . II I . . . . .. .. . . R I . . 1 R I R R R CYATHEA MEDULLARIS I II I . . . . . . . . . CYATHEA CUNNINGHAMII I I 1 . . R ASPLENIUM BULBIFERUM V IV IV V 1V IV IV 1V II I . . R IV I!I • . IV I I 1 1 1 1 R 1 1 1 I BLECHNUM CHAMBERSII IV III IV IV IV III IV 1 III I . R . . . III HI. I . I R R R 1 R . . BLECHNUM NIGRUM I1. I I . I I [ 11 I [ R II . R I BLECHNUM COLENSOI I II I1 I 1 I I I I . . R . . R . R LEPTOPTERIS HYMENOPHYLLOIDES II I I 1 I I I R I I LEPTOLEPIA NOVAE-ZELANDIAE II I II I II I II I R 1 I . R MUEHLENBECKIA COMPLEXA I . R I I1 R . . R R I R 1 I R I I NERTERA CUNNINGHAMII I . R I1 II 1 II I . R^ R R RI FitR R . I PNEUMATOPTERIS PENNIGERA I II . I . R II R LASTREOPSIS GLABELLA I I . . . I R R R PARSONSIA HETEROPHYLLA I . R . R R R R CLEMATIS AUSTRALIS 1 I . 1 R. . . . . . . . . . . . . . . . . . . . .

DACRYCARPUS DACRYDIOIDES SPECIES GROUP, USED TO DISTINGUISH THE DACRYCARPUS DACRYDIOIDES COMMUNITY (C):

DACRYCARPUS DACRYDIOIDES R . R . . . . 1 V II I . R ASTELIA GRANDIS I III . . .

DACRYDIUM CUPRESSINUM SPECIES GROUP, USED TO DISTINGUISH THE DACRYDIUM CUPRESSINUM COMMUNITY GROUP; LESS FREQUENTLY ALSO IN E:

DACRYDIUM CUPRESSINUM I R V V V V V V IV V V R R . . • • • . R . . . . . . . • . . I ELAEOCARPUS DENTATUS • R I IV 11 I1 IV II II R R . . . . . . . . . . . . . . . . . MYRSINE SALICINA II II I I III I II I RR 1 . . . . . . . . . . . . . . . . . . . ASTELIA SOLANDRI R . R . . , . II III II I 11 I I . 1 . , , , , , , , R HYMENOPHYLLUM LYALLII . . . . .. . R R I V I R . . • • • •R . I . . . R . . . PTEROSTYLIS GRAMINEA R I . . .. I . R II I . I I R I R R R R ALSEUOSMIA PUSILLA . . . I • • . I I R . I R I . ill 1 GRISELINIA LUCIDA . . . . . . . II R ^

MYRTUS PEDUNCULATA SPECIES GROUP, INCLUDING SPECIES WITH MAIN DISTRIBUTION WITHIN THE DACRYDIUM CUPRESSINUM COMMUNITY (D):

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11 Phytocoenologia 16 ABBREVIATION OF COMMUNITY TYPE Al A2 A3 A4 A5 A6 B1 Cl D1 D2 D3 D4 D5 D6 07 D8 El E2 E3 E4 Fl F2 G1 G2 H1 H2 H3 H4 H5 H6 Il 12 13 14 J1 J2 K1 11 L2 L3 L4 L5 L6

NUMBER OF RELEVES 72 7 26 16 14 23 8 14 9 60 12 12 25 15 15 22 54 64 10 48 16 24 7 11 32 7 70 16 30 11 29 20 11 71 15 25 19 23 56 29 20 6 14

CYATHEA COLENSOI SPECIES GROUP, INCLUDING SPECIES WITH MAIN DISTRIBUTION IN LIBOCEDRUS BIDWILLII-, HOHERIA GLABRATA COMMUNITY GROUP:

CYATHEA COLENSOI R . R . I I . I . . I I IV IV I . IV V IV V II II V IV . II . R R II 1 LEPTOPTERIS SUPERBA II . II. II I . II I II II . I 1 . I lI II I II III II I IV III III IV I I III III . UNCINIA ANGUSTIFOLIA R . I I . R • . . R R R . II II . I II II I II R II II 1 . R R R R UNCINIA GRACILENTA . I . R . II . I I . R . . . R . . R I . . . I . R I

EMPODISMA MINUS SPECIES GROUP USED TO DISTINGUISH THE EMPODISMA MINUS SUBDIVISION OF THE HALOCARPUS BIFORMIS - GAHNIA PROCERA - COMMUNITY (J2): 1 NOTHOFAGUSMENZIESII RI ...... R R III CYATHODES JUNIPERINA R III CYATHODES EMPETRIFOLIA R III EMPODISMA MINUS . . .. .. . . . . . . III DROSERA SPATHULATA . . .. . . . III APOROSTYLIS BIFOLIA . . . . R . . . R . . I II • DRACOPHYLLUM PALUSTRE . . . . . . . I LYCOPODIUM RAMULOSUM . . . . .. . . . . . . II THELYMITRA VENOSA II PENTACHONDRA PUMILA II GLEICHENIA DICARPA II SCHIZAEA FISTULOSA II DROSERA STENOPETALA I OREOBOLUS PECTINATUS II

LEPTOSPERMUM SCOPARIUM SPECIES GROUP; USED TO DISTINGUISH THE HALOCARPUS BIFORMIS COMMUNITY GROUP, THE INCLUDING HALOCARPUS BIFORMIS-GAHNIA PROCERA COMMUNITY (J): LEPTOSPERMUMSCOPARIUM . . R . . . . . . . . . . . . . . . . . . . . . . I R 3 V LAGAROSTROBUSCOLENSOI . . . . . . . . . . . . . . . I . . . . . . . . . . I I . ▪. . R II III LEPIDOTHAMNUS INTERMEDIUS R . . . R .. . . . R I. LEPIDOTHAMNUSLAXIFOLIUS . . . . . . . . . . . . . . . . . . . . . . ▪. . . . . . . GAULTHERIA CRASSA . . . . . . . . .I I I ABROTANELLALINEARIS . . . . . . . . . . . . . . . . . . . . . . , , , , , , , I , ▪ . II R GENTIANA SPEC. I I I

PHYLLOCLADUS ASPLENIIFOLIUS SPECIES GROUP; USED TO DISTINGUISH THE HALOCARPUS BIFORMIS-GAHNIA PROCERA COMMUNITY; USED TO DISTINGUISH THE SUBDIVISIONS D7, 08; H5, H6; 14: PHYLLOCLADUS ASPLENIIFOLIUS R I . R I III V . . . . . R . I II V V I . II 3 V R R HALOCARPUS BIFORMIS . . . . . . . . . . . . . R . . . I II V II 1 I V IV V R ELAEOCARPUS HOOKERIANUS . . . . . . . II . . . . . . I II . R . .. . . R I II I 1 . II III I GAHNIA PROCERA IV III . . . . . R . . I V V . . . V 3 V HALOCARPUS BIDWILLII . . . I .

RAOULIA TENUICAULIS SPECIES GROUP; USED TO DISTINGUISH THE RAOULIA TENUICAULIS COMMUNITY (K):

RAOULIA TENUICAULIS , , . .. . . TRISETUM ANTARCTICUM AGG. v . . . ... . II POA COCKAYNIANA . R ,. . R . . . . II I I . CORTADERIA RICHARDII SPECIES GROUP; USED TO DISTINGUISH THE CORTADERIA RICHARDII SUBTYPE:

CORTADERIA RICHARDII . . . . . R , • • • HELICHRYSUM BELLIDIOIDES iJ GROUP, SPECIES GROUP USED TO DISTINGUISH THE HELICHRYSUM BELLIDIOIOES SUBDIVISION OF THE HEBE SALICIFOLIA COMMUNITY. ALSO OCCURRING IN THE TENUICAULIS COMMUNITY: HELICHRYSUM BELLIDIOIDES . . . . . . . . . , , , . , R . . II III FORSTERA TENELLA . . . . . . . . I R , , I . R . R . I R . I II PARAHEBE LYALLII . . , , , , , , . R I II ACAENA PROFUNDEINCISA R . . . I . . . . . . . . . I1 II 1 1I ^ LUZULA PICTA • • I . . . . . , . . . , . , . , I R .. . . . R . . R . I III HYDROCOTYLE NOVAE-ZELANDIAE . 1 . . . R . . , , , . , , , , . • II I . I R . . . . . R . . . I II RYTIDOSPERMA SETIFOLIUM , , , , , , , , , , . . . . I , . . . . . , , , , . . . . . I I HEBE SUBALPINA .. . I . . . . . . . . . . . , . I . . R . R . . . . . . . . I1 EP{LOBIUM CF. BRUNNESCENS ... . . . I . . . . . . . . . . . • •. I R . . . . . . . . . . . I II POA COLENSOI .. . . . . . . . . . . . . . . . . . I . . . . . . . . . . . . II HYDROCOTYLE MICROPHYLLA • • . I . . . . . . . . . . . . . . . . R . I I . . . R AGROST . • • . II IS "CANINA" • . . I , R . . . . . . . . . . .. . . I . . . . . . HYDROCOTYLE MOSCHATA R AGROSTIS "PERENNANS" R GNAPHALIUM TRINERVE ERECHTHITES WAIRAUENSIS OURISIACAESPITOSA . . . , .. , , , , , , , , , , . . . , . . . . , . . . COTUL A SQUALIDA • • . . .. . . . . . . . . . . GNAPH . • • I I . . R . . . . . . . ALIUM PALUDOSUM • • • , , I , , , , , , , .. , , . . , , . , , . , . . , CAREX COCKAYN I ANA • • • I .. . . . . . . . . . .. . . 1 1 . . R . . . . . .

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3.1.1. Melicytus ramiflorus community group (A, B)

The Melicytus ramiflorus community group was differentiated by the Melicytus ramiflorus species group, including a variety of small trees, e. g., Melicytus ramiflorus and Carpodetus serratus; lianes, e. g., Ripogonum scandens; shrubs; and herbaceous species. Ferns were abundant in the ground tier. Species of the Blech- num fluviatile species group, including Blechnum fluviatile, broadleaved Uncinia- species and the small tree Pittosporum colensoi were common. Species of this species group were also frequent in other early successional community groups, e.g., the Hoheria glabrata — (subsection 3.1.2.) and the Hebe salicifolia (subsection 3.1.6.) community groups. Many of the most frequently encountered species of the conifer-broadleaved hardwood forests (e.g., Weinmannia racemosa species group, containing the dominant hardwood canopy species) were rare or occurred mainly as epiphytes or shrubs of epiphytic origin, e. g., kamahi and Quintinia acuti folia. The Melicytus ramiflorus community group contained low statured forest (usually less than 8 m tall) and shrubland on recent soils up to c. 750 m altitude (Appendix 5). Similar communities occurring on similar sites have been described previously (e.g., COCKAYNE 1 928; J. WARDLE HAYWARD 1970; P. WARDLE 1977, 1980a; COLEMAN et al. 1980). The Melicytus ramiflorus community group included the Melicytus ramiflorus — Carpodetus serratus community (A) and the Coriaria arborea community (B). The first one is a "pure" community, because all species also occurred in the Coriaria arborea community, and the typical feature is the absence of Coriaria arborea. The Melicytus ramiflorus — Carpodetus serratus community was encountered frequently, whereas the Coriaria arborea community was restricted to a few sites. Homotoneity (between-stand uniformity; a value calculated after MORAVEC 1972 as the proportion of species occurring on more than 60 % of the relevēs in a group of relevēs divided by the average number of species per relevē in a type, and allows for differences in the number of relevēs in a type) was generally low in all community types of this community group (Appendix 3).

Melicytus ramiflorus - Carpodetus serratus community

Csm

/Tree fern (dead)

Tree fern (dead)

Sample: Camp creek 134 Altitude: 320 m Aspect: W Slope: 10 ° Physiography: Face Parent Material: Schist Notes: Windfall canopy gap.

Fig. 5. Melicytus ramiflorus — Carpodetus serratus community in a canopy gap. Melicytus ramiflorus is the dominant canopy species. Species abbreviations are listed in Appendix 1.

Melicytus ramiflorus-Carpodetus serratus community

Qa (epiph.)

Faultline Sample: Hari Hari 93 Altitude: 600 m Wr(epicormics) Aspect: W Slope: 25° Physiography: Face Parent Material: Schist

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Fig.g 6. Melicytus^ rami onus — Carpodetus serratus .. mmuni communitydominatedty bby C atbea smzthss on a landslide a line the forest had taller trees ^ adjacentdJ to a faultline. Below thee fcult - with larger^ diameters. Speciesp es abbreviations are listed in Appendix 1. 172 A. Reif R.B. Allen

However, where the soil was kept immature through periodic disturbance, e.g., in gullies by regular alluvial deposition or by soil creep on steep slopes (P. WARDLE 1980a), the seral character of the Melicytus ramiflorus -- Carpodetus serratus community was maintained. Sites subjected to repeated disturbance, such as from tectonic activity, were forested mainly by short-statured vegetation. The Melicytus ramiflorus — Carpodetus serratus community could be found surrounded above and below by forests of the Prumnopitys ferruginea — Coprosma lucida community (Fig. 6). Tectonic activity resulting in similar forests with similar species composition were described in areas of West Nelson (ROSE 1985). The Melicytus ramiflorus — Carpodetus serratus community was often associated with sites in gullies subject to regular flooding (Fig. 7), resulting in erosion and deposition processes that rejuvenate the soil. Under these conditions, slow growing and long-living tall forest trees probably cannot establish because of the rapid invasion of herbs, and the seral character of the vegetation is maintained. Where small streams were present in gullies, Uncinia uncinata was often dominant on an accumulation of alluvium. Where there was steep rocky sites due to downcutting Blechnum colensoi was frequent. Where repeated disturbance was less severe than due to flooding in gullies, as found along lower parts of faces, the canopy was uneven, with a mosaic of trees and tree groups surrounded by a dense shrub vegetation. On such sites colluvial deposition resulted in vegetation which was transitional between the Melicytus

Melicytus ramiflorus-Carpodetus serratus community

Sd F

F Csm 8m

Pdi(epiph.) Sample: Karangarua/Copland Altitude: 470 m Aspect: E Slope: 20° Physiography: Gully Parent Material: Schist

Fig. 7. Melicytus ramiflorus — Carpodetus serratus community. Seral vegetation in gully dominated by Fuchsia excorticata. Species abbreviations are listed in Appendix 1. Steepland conifer-broadleaved hardwood forests of central Westland 173

ramiflorus -- Carpodetus serratus community and the Prumnopitys ferruginea — Coprosma lucida community. With increasing disturbance the seral species of the Melicytus ramiflorus group were favoured over long-lived tree species, e.g., of the Weinmannia racemosa species group. On such sites the canopy was broken, with emergent and isolated kamahi trees. This may be (1) due to infrequent success of kamahi to establish as a tree from epiphytes, and (2) because disturbance has only partly destroyed the forest already occupying the site, resulting in sur- vival of a few remnant tall forest trees surrounded by species of the melicytus ramiflorus group (P. WARDLE 1980a). A gradient in species composition along a toposequence resulted in the sequence of related vegetation types between the two communities. Variation in species composition also occurred within the Melicytus ramiflorus — Carpodetus serratus community between localities. Some of these differences appear to be a consequence of the impact of introduced browsing animals. This seral community has been subject to intensive animal usage at some localities (e.g., J. WARDLE HAYWARD 1970; P. WARDLE 1977). Fuchsia excorticata was a dominant canopy species only in the Karangarua and Copland catchments (Fig. 7), yet previous workers have described it as more widely distributed than in this study (COCKAYNE 1928, p. 171). This species is palatable to brush-tailed possums (PEKELHARING REYNOLDS 1983). Additional evidence for the removal of Fuchsia excorticata due to browsing pressure comes from the recovery of defoliated trees when protected from browse (COLEMAN et al. 1985). In a few other localities, e. g., the granite areas (Te Kinga), Fuchsia excorticata persisted as a sub-canopy tree, although not widely distributed, where brush-tailed possums have long been established. Within this community, Pseudowintera colorata was a widely distributed species, yet, it was found more frequently and with higher cover at certain localities. This occurred even within a community type, e.g., the two types of the Hoheria glabrata subdivision. Pseudowintera colorata was most frequent in catchments where high deer densities have been present in the past, e. g., in the Kokatahi ("Pseudowintera colorata facies"). Similar stands were recorded by COLEMAN et al. (1980) as "Pepperwood scrub" from Mt. Bryan OLynn, Westland. Ex- closure studies have shown Pseudowintera colorata to be more abundant where there is browsing by red deer (ALLEN et al. 1984). It was less frequent in areas with low deer densities, e. g., at Fox.

3.1.1.2. Coriaria arborea community (B) Coriaria arborea dominates as a shrub below 700 m altitude along alluvial fans and talus areas adjacent to streams "... where there is plenty of water percolating through the substratum" (P. WARDLE 1977). The distinction of a Coriaria arborea community within the Melicytus ramiflorus community group was partly based on previous descriptions (COCKAYNE 1928; P. WARDLE 1977). The Coriaria arborea community sampled occurred in schist areas near Fox and Camp Creek (Appendix 5, 6). Because this study was of steepland vegetation, few sites where this community occurs were sampled. Similar vegetation from the western parts of South Island is described by COCKAYNE (1928). 174 A. Reif R.B. Allen

The canopy of the Coriaria arborea community was usually less than 10 m tall. Coriaria arborea dominated in the canopy. Other species, e.g., of the Melicy- tus ramiflorus- and of the Hebe salicifolia species groups were usually present in the understorey. Epiphytes, particularly the ferns Asplenium flaccidum and Phymatosorus diversifolius, were frequent.

3.1.2. The Prumnopitys ferruginea community group (C, D, E)

The Prumnopitys ferruginea community group included forest with: miro (Prum- nopitys ferruginea) in the tree tier; karamu (Coprosma lucida), Pseudopanax crassifolius and Myrsine australis in the shrub tier; the ferns Blechnum discolor and Hymenophyllum demissum in the ground tier; and species usually found as epiphytes (Hymenophyllum flabellatum, Hymenophyllum peltatum and Tmesip- teris tannensis agg.). All of these species had their main centre of distribution within these forests. In these forests the dominant canopy trees were usually kamahi and Quintinia acutifolia, overtopped by taller conifers (up to 30 m tall). Widely distributed low altitude species usually present included the treeferns Dicksonia squarrosa and Cyathea smithii, the rootclimbing Metrosideros diffusa fusa and Metrosideros perfora- ta, and in the ground tier an undescribed Blechnum-species (Blechnum "black spot") and Nertera dichondriaefolia. Ferns usually found as epiphytes included Phymatosorus diversifolius, Rumobra adiantiformis, Trichomanes venosum, Tri- chomanes reni forme, and Hymenophyllum dilatatum. Within the Prumnopitys ferruginea community group, species richness was lowest at altitudes between 400 and 500 m a. s. 1. (Appendix 4). Within this altitudinal band, many low altitude species already have disappeared, and many high altitude species were not yet competitive. The Prumnopitys ferruginea community group included communities occurring up to c. 650 m altitude (Appendix 5). It contains three communities, the Da- crycarpus dacrydioides community (C), the Dacrydium cupressinum community (D) and the Prumnopitys ferruginea — Coprosma lucida community (E).

3.1.2.1. Dacrycarpus dacrydioides community (kahikatea forest, C)

Kahikatea (Dacrycarpus dacrydioides) and Asteliagrandis were differential-species of the Dacrycarpus dacrydioides community (Table 2). Also present were species of the Dacrydium cupressinum group and species of seral sites, e. g., the Melicytus ramiflorus-, Coprosma ciliata- and Blechnum fluviatile species group. Kahikatea forest had the highest average number of species per relevē of all community types sampled (Appendix 3). Also frequent were species of the Weinmannia racemosa group, including kamahi, Pseudopanax simplex, Coprosma foetidissima and Pseu- dopanax colensoi. Epiphytically established broadlef trees were also common. Silver beech (Notbofagus menziesii) occurred in southern parts of the study area (Douglas Range, Hunt Hill; P. WARDLE 1980 b), on some relevēs beneath the emergent kahikatea instead of kamahi. Kahikatea forest was typically found on alluvial terraces. These sites were often poorly drained and ponded water was sometimes present. Kahikatea forest Steepland conifer-broadleaved hardwood forests of central Westland 175 was encountered up to 300 m altitude, mainly adjacent to forest dominated by rimu. On such sites it has been described by a number of authors (COCKAYNE 1928; FOWERAKER 1929; MARTIN 1932; P. WARDLE 1974, 1977). P. WARDLE (1977) described a "kahikatea forest" on recent alluvial soils, a "kahikatea/hardwood forest" on recent soils and a "rimu/kahikatea forest" on relatively fertile gley podzols. Most of the relevēs in this study belong to the "rimu/kahikatea forest" sensu P. WARDLE (1977). Because this study was of steepland forest the few kahikatea stands sampled represent a transition from kahikatea forest to rimu forest, not a "pure" community. In Westland National Park some stands described as "kahikatea/hardwood forest" still have their first generation of podocarps (P. WARDLE 1977). Tree seedlings often establish epiphytically on tree stumps, logs and other raised surfaces and stands usually have a mixed range of tree diameters. With an absence of further flood deposition fresh soils are "... maturing to the disadvantage of kahikatea" (BATHGATE 1981), and it is generally assumed that kahikatea forest is replaced by forest dominated by rimu (Dacrydium cupressinum) (P. WARDLE 1980a).

3.1.2.2. Dacrydium cupressinum community (rimu forest, D)

The Dacrydium cupressinum community was differentiated by the tree species rimu and hinau (Elaeocarpus dentatus), in the ground tier by Pterostylis graminea and Alseuosmia pusilla, and by the epiphytic Astelia solandri. In the northern parts of central Westland (e. g., Hohonu Range) Myrsine salicina, Hymenophyllum lyallii and infrequently Griselinia lucida occurred. Species of the Myrtus pedunculata species group have their main center of distribution in the Dacrydium cupressinum community, particularly in the community types at lower altitudes. However, they are only weakly differentiating species, as they were also found in miro-karamu forest and other communities. The Dacrydium cupressinum community (rimu forest) was frequently encountered on ridges and upper faces below c. 650 m altitude. Soils were often strongly leached. In the extensive rimu forests found on the fluvioglacial terraces to the west of the area sampled the soils have developed to gley podzols (CUTLER 1960, P. WARDLE 1977), often with a pronounced raw humus layer (BURNS 1931). Within rimu forest, a Melicytus ramiflorus subdivision (D1, D2, D3), a Pure subdivision (D4, D5, D6), and a Phyllocladus aspleniifolius subdivision (D7, D8) were distinguished (Fig. 4; Table 2). The Melicytus ramiflorus subdivision was mainly encountered in schist areas on lower slopes and terraces, often where there was alluvial and colluvial deposition. Disturbances resulting in freshly exposed soil, such as upturned root plates, often led to the establishment of species from the Melicytus ramiflorus species group along with species of disturbed sites, e. g., Histiopteris incisa, Paesia scabe- rula and Hypolepis rugosula. In the Pure subdivision, species richness was lower than in the Melicytus ramiflorus subdivision (Appendix 3), mainly because of competitive exclusion of other species by the presence of frequent, dominant species. Forests with a similar canopy species composition to the Pure subdivision have been described 176 A. Reif & R.B. Allen on podzolised yellow-brown earths (CUTLER 1960; P. WARDLE 1977). Such forest usually occurred on the lower slopes below the Phyllocadus aspleniifolius subdivision in granite areas, and further upslope than the Melicytus ramiflorus subdivision, on ridges and upper faces, in schist areas. The Pure subdivision and the Melicytus ramiflorus subdivision were each further differentiated into three types (D1 to D3 and D4 to D6 respectively). A Pure type (D3 and D6) was found between c. 400 m to 600 m a.s.l. (Appendix 5). A Ripogonum scandens type (D2 and D5) occurred between c. 200 m and 400 m. A Freycinettia baueriana type (Dl and D4) was found at the lowest altitudes, below c. 3 50 m. It also contained species of the Ripogonum scandens species group, resulting in species-rich rimu forest types (Appendix 3). The Phyllocladus aspleniifolius subdivision was mainly encountered in granitic areas (Appendix 6) on stable sites, where it was frequent at altitudes above c. 400 m. It was subdivided by species of the Libocedrus bidwillii species group in- to a Pure type (D7) and a Libocedrus bidwillii type (D8). Southern rata and Halls totara were more frequent and with greater cover than in other subdivisions. Quintinia acutifolia was found with higher canopy cover than kamahi, particularly in the Libocedrus bidwillii type. Tmesipteris tannensis agg., Grammi- tis billardieri agg. and other typically epiphytic species were frequently found growing terrestrially. On poorly drained sites within the Phyllocladus aspleniifolius subdivision, e. g., on terraces with impeded drainage, species usually found at higher altitudes could compete and were present with species of lower altitudes. This resulted in a Libocedrus bidwillii type (D8), with an unusual canopy composition of low statured rimu and codominant Libocedrus bidwillii. This community type represents a transitional stage towards the Halocarpus biformis — Gahnia procera community (Fig. 4). The Melicytus ramiflorus subdivision often represented a successional stage in a canopy gap, but, also appeared to form a stable community maintained by repeated soil rejuvenation. Where best developed there were only scattered rimu trees surrounded by kamahi and small, fast growing trees ("scrub hardwoods"). Floristically the Pure subdivision represented a transition between the Melicy- tus ramiflorus and the Phyllocladus aspleniifolius subdivisions and largely reflected differences in site stability. P. WARDLE (1977) described three types of forest with rimu from Westland National Park. On yellow-brown earth soils, where "... slopes steep enough to prevent podzolisation without slipping ...", he described a "Rimu/kamahi/Blechnum forest" in several variants. This forest on immature soils corresponds with the Melicytus ramiflorus subdivision. A "Ri- mu/kamahi-Quintinia forest" was found on "... gleyed podzolised yellow-brown earths with a cemented B horizon ...". This roughly corresponds with the Da- crydium cupressinum community, Pure subdivision. A "Rata-kamahi/Gahnia forest" outside the study area in the lowlands of Westland National Park occu- pies "... weakly podzolised yellow-brown earths on crests and upper slopes in the piedmont area, usually on moraine but also on grey-wacke. The community ascends to 600 m" (P. WARDLE 1977). Rimu forest, together with kahikatea forest, can form the tallest forests (main canopy height c. 30 m) in central Westland. In the sub-canopy kamahi, Quintinia Steepland conifer-broadleaved hardwood forests of central Westland 177 acutifolia and hinau can occur. Often it appears regeneration of tree species, including the conifers, occurred where single large canopy trees had toppled and seedlings had established on fallen logs, root-plates and other raised areas. A dense ground cover appears to limit the establishment of rimu seedlings (FRANK- LIN 1968). The result was a small-forest pattern with an uneven canopy (Fig. 8), resulting from a mosaic of low vegetation in windfall gaps, or pole stands, between more extensive areas of taller forest. Shade tolerant species such as Quin- tinia acutifolia, kamahi, and hinau can also regenerate under a closed canopy in a more continuous mode. Stands with a mixed range of diameters for all canopy tree species appeared best developed in the Phyllocladus aspleniifolius subdivision. It may be that the establishment of tree seedlings occurs continuously where there is an absence of a dense herbaceous layer. A few stands indicated that at times disturbances may lead to large canopy gaps up to a hundred meters in extent. Logs and upturned root plates were found on the forest floor even where a tall forest had developed. On one relevē, logs were lying on the forest floor parallel in one direction, indicating a windthrow. The canopy species were regeneration along the old logs. Canopy gaps were often filled with regenerating along the old logs. Canopy gaps were often filled with vigorous and dense Quintinia saplings together with some kamahi and other species. This is similar to the extensive windthrows in dense rimu forests on gley podzols of the piedmont moraines west of the study area described by HUTCHINSON (1928, 1931) where evenaged groups of conifers develop through a phase of hardwood dominance after windthrow (POOLE 1937). Disturbances in rimu forest which exposed new mineral surface allowed the establishment of seral species, e. g., of the Melicytus ramiflorus species group.

3.1.2.3. Prumnopitys ferruginea-Coprosma lucida community (miro-karamu forest, E)

All species found in the Prumnopitys ferruginea-Coprosma lucida community also occurred in other communities. A typical feature was the absence of species from the Dacrycarpus dacrydioides species group and the Dacrydium cupressinum species group. The Prumnopitys ferruginea -- Coprosma lucida community (miro-karamu forest) was the most frequent forest type sampled in schist localities below c. 750 m a.s.l. (Appendix 5), but was infrequently encountered in granite areas (Appendix 6). This pattern is supported by a similar community from north Westland being described more, frequently on schist areas, based on a restricted random plot location (J. WARDLE 1974). The Prumnopitys ferruginea — Copros- ma lucida community was usually found on ridges and upper slopes of faces, and infrequently on terraces and in gullies. Soils were less developed than in the Da- crydium cupressinum community. Soils included those with barely any "B" horizon development and were relatively weakly weathered, and classified as more recent to developed yellow-brown earths (HARRISON 1985 a, 1985 b). Soils were usually free draining. Similar forests have been described by a number of authors for central Westland (COCKAYNE 1928; J. WARDLE HAYWARD 1970;

12 Phytocoenologia 16 Dacrydium cupressinum community

Bd Cc Sample: Hohonu 176 Ground Cover %: Fallen Altitude: 470 m Vascular: 20 logs GI Cc Pcr Aspect: SE Non-vascular: 50 Slope: 15 ° Litter: 30 Physiography: Face Bare Ground: - Parent Material: Granite Rock: -

Fig. 8. ^Dacrydium p cupressinum community.y Tree speciesp established dominantlytlY on logs^ and root platesP in windfallgP gap. QQuintinia acutifoliaacuts and Weinmannia racemosa regenerating gy abundantly in canopypy gap.g p Largeg Metrosideros umbellatambellata and Dacrydiumr'Y cupressinump are remnants. SpeciesP abbreviations are listed in Appendixpp 1. Steepland conifer-broadleaved hardwood forests of central Westland 179

P. WARDLE 1977; COLEMAN et al. 1980) and from areas outside Westland, e.g., a "Weinmannia/Cyathea forest" from Fiordland (P. WARDLE 1963 c). A Melicytus ramiflorus subdivision (E1 , E2) was differentiated from a Pure subdivision (E3, E4; Fig. 4). Both subdivisions were further subdivided into a Ripogonum scandens type (El, E3) which was found up to c. 450 m altitude; and a Pure type (E2, E4) which mainly occurred between 400 and 650 m (Ap- pendix 5). The Melicytus ramiflorus subdivision (E1, E2) was encountered on ridges and upper faces, but also on lower slopes and adjacent to gullies on immature soils. A floristically similar forest type was defined by P. WARDLE (1977) as "Kamahi/ Schefflera forest". This forest is "... characteristic of steep slopes and gullies where the soil is kept loose and immature through soil creep. Unweathered rocks may rise to the surface, although in places the matrix can develop the weathered, yellow-brown appearance of mature hill soils" (P. WARDLE 1977). Soils of a floristically similar "Weinmannia/Cyathea forest" from Fiordland had relatively high nutrient concentrations (P. WARDLE 1963c). Kamahi seedlings frequently occurred on treefern trunks (Cyathea smithii), and to a lesser extent on logs. Miro mainly occurred as seedling or saplings of epiphytic origin, but, infrequently as canopy trees. Quintinia and southern rata were rare or absent. This subdivision formed the transition between the Prumnopitys ferruginea — Coprosma lucida community and the Melicytus ramiflorus — Carpodetus serratus community. A similar transitional forest type, "kamahi forest", was described and regarded as seral by J. WARDLE HAYWARD (1970). The Pure subdivision (E3, E4) typically occurred on upper faces and ridges. Most sites were stable. Soils were shallow over bedrock and were generally more developed than in the Melicytus ramiflorus torus subdivision. P. WARDLE (1977) described similar forests from Westland National Park as "Rata-kamahi/Blechnum forest" on yellow-brown earth: "... This upland equivalent of rimu/kamahi/ Blechnum forest ... occurs on the main ranges to an altitude of 650 m. It is chiefly on the outer slopes but grows also on the slopes of the lower reaches of the mountain valley" (P. WARDLE 1977). Quintinia acutifolia was the dominant tree species regenerating in canopy gaps on ridge sites. Similar to the Dacrydium cupressinum community, species richness was higher in the Melicytus ramiflorus subdivisions than in the Pure subdivisions (Appendix 3). In most areas miro-karamu forest had a dense canopy dominated by kamahi and Quintinia acutifolia, species which had their main center of distribution in this community, and by southern rata. Emergent southern rata and miro were often the largest trees, and probably the oldest. In the understorey, Coprosma foetidissima, Pseudopanax simplex, Pseudopanax colensoi and saplings of kamahi and Quintinia acutifolia olia were widely distributed in the shrub tier. Rimu poles occurred in the understorey only on a few stable faces and ridges, and on these sites miro-karamu forest may be replaced in time by rimu forest. Other species of the Dacrydium cupressinum- and Myrtus pedunculata species group were also present on these relevēs. Stands at different stages of development were found within the miro-karamu forest. In many areas on steepland sites there were extensive young stands with trees of relatively small diameter (Photo 1). The trees were more or less even- 180 A. Reif R.B. Allen sized, and probably more or less even-aged (P. WARDLE 1977; STEWART VEB- LEN 1982). Southern rata was mixed with kamahi and Quintinia acutifolia. Miro and Podocarpus hallii were present as epiphyts, terrestrial seedlings and as saplings, but, usually not in the canopy. These forests are typical of steeper parts of faces and ridges. In most relevēs, these stands appear to be the result of landslides which often expose the bedrock on faces and sharpen existing ridges. P. WARDLE (1977) suggested that a major earthquake about 250 years ago triggered massive landslides throughout the whole central Westland region. Regeneration on landslide surfaces favoured the opportunistic and lightde- manding species. Young even-sized pole stands develop, often dominated by southern rata, and less frequently by kamahi and Quintinia acutifolia (DOBSEN et al. 1977; STEWART VEBLEN 1982) (Photo 1).

Photo 1. Even-sized and probably even-aged forest with canopy dominated by southern rata (Metrosideros umbellata) and kamahi (Weinmannia racemosa), surrounded by dieback forest. — Kokatahi, Westland. Steepland conifer-broadleaved hardwood forests of central Westland 181

Prumnopitys ferruginea -Coprosma lucida community

25m

Sample: Camp creek 68 Ground Cover %: Altitude: 580 m Vascular: 5 Aspect: - Non-vascular: 15 Slope: 0° Litter: 85 Physiography: Terrace Bare Ground: - Parent Material: Schist Rock: -

Fig. 9. Prumnopitys ferruginea — Coprosma lucida community. Open canopied stand of Me- trosideros umbellata with sub-canopy of Weinmannia racemosa and Quintinia acutifolia. Dense thicket of Quintinia acutifolia c. 2 m high. Species abbreviations are listed in Appen- dix 1. 182 A. Reif R.B. Allen this forest were classified into the Melicytus ramiflorus — Carpodetus serratus community. Although, the presence of surviving large miro trees (ALLEN ROSE 1983) indicate such forest was previously miro-karamu forest.

3.1.3. Hoheria glabrata community group (F, G)

The Hoheria glabrata community group included the floristically similar Hoheria glabrata community (F) and Plagianthus betulinus community (G). In this study these two communities differ from all other communities in that the dominant canopy tree species, Hoheriaglabrata and Plagianthus betulinus (both Malvaceae), are deciduous. Plagianthus betulinus appears to form the tallest (up to 10 m) deciduous forest in New Zealand. These trees occurred on recently disturbed well drained soils, often on sites subject to cold air drainage.

3.1.3.1. Hoheria glabrata community (F)

The forest canopy in the Hoheria glabrata community was often dominated by Hoheria glabrata, in some cases forming pure stands, and less frequently by Olea- ria ilicifolia. Other species present in the tree tier included Olearia lacunosa and Griselinia littorglis (broadleaf). On toe slopes scattered individuals of Libocedrus bidwillii, southern rata and Halls totara were also present in the tree tier. The forest canopy was usually less than 8 m high. In the shrub tier Coprosma ciliata and Pseudowintera colorata were often the dominant species. The fern Polysti- chum vestitum and the sprawling sub-shrub Coprosma depressa usually formed a dense ground tier. Where there was evidence of recent disturbance, e. g., along stream escarpments, Histiopteris incisa, Hypolepis millefolium, Uncinia spp. and Blechnum fluviatile occurred with higher cover. Species richness was high relative to other communities (Appendix 3), mainly because of the presence of many wide-ranging species. The Hoheria glabrata community was encountered in gullies and along toe slopes on sites above c. 600 m a. s.1. altitude (Appendix 5). On these sites soils were often recent, developing on colluvium from landslides and rockfalls, ava- lanche debris and alluvium. Constant deposition ensures these soils maintain relatively high fertility (HARRISON 1985 b). Such disturbances appear more frequent and extensive in areas underlaid by schist than by granite, and most relevēs of this community were from the schist area (Appendix 6). Where this community was found in areas underlaid by granite it was largely confined to valley heads and was absent from interfluve areas. Previous studies have described forests dominated by Hoheria glabrata as occurring under similar conditions in central Westland (e. g., P. WARDLE 1 960; J. WARDLE HAYWARD 1970; P. WARDLE 1977), and elsewhere (e.g., P. WARDLE 1963 c). Two subdivisions of the Hoheria glabrata community were distinguished, a Carpodetus serratus subdivision (F1) and a Dracophyllum traversii subdivision (F2). Floristic differences between these subdivisions were largely related to altitude. The Carpodetus serratus subdivision was encountered on sites up to c. 900 m altitude (Appendix 5). This subdivision was distinguished by species typically Steepland conifer-broadleaved hardwood forests of central Westland 183 found in forests at lower altitudes, and was differentiated by species of the Me- licytus ramiflorus species group. Species present in the canopy, along with Ho- heria glabrata, included Scheffleraf lera digitata, Aristotelia serrata, and less frequently Fuchsia excorticata. The species composition of this subdivision represented a transition to the Melicytus ramiflorus — Carpodetus serratus community, found on similar sites below c. 650 m altitude. Above an altitude of c. 800 m a. s. 1. the Dracophyllum traversii subdivision was found, and corresponds to the "Subalpine low Hoheria forest" of P. WARD- LE (1 977). Other prominent species included Olearia lacunosa and Chionochloa conspicua. The Hoheria glabrata community was characteristic of sites where disturbance has resulted in the rejuvenation of soils. Where the site remains stable there was some evidence for a shift in species composition. For example, on sites where canopy trees were found as large diametered individuals (e. g., Hoheria glabrata and Olearia lacunosa with c. 50 cm d. b. h.; Fig. 10) an abundance of epiphytic mosses (e.g., Weymouthia cochlearifolia, Dicnemon calcycinum) and liverworts (e.g., Porella elgantula) occurred, and it appears that there were only few small- sized individuals of Hoheria glabrata. Species such as Coprosma ciliata, C. depressa and Pseudowintera colorata appear to be more frequent than in stands where Hoheria glabrata was of smaller stature. These species along with others (e.g., species of the Cyathea colensoi species group) become more frequent on sites

Lb Hoheria glabrata community

Sample: Camp creek 212 Ground Cover %: Altitude: 920 m Vascular: 60 Aspect: NW Non-vascular: 25 Slope: 20° Litter: 10 Physiography: Ridge Bare Ground: - Parent Material: Schist Rock: 5

Fig. 10. Hoheria glabrata community. Stand along edge of river terrace. Large Olearia lacunosa (10 m tall; 50 cm d.b.h.) and Myrsine divaricata (8 m tall; 20 cm d.b.h.) present. Few seedlings of Hoheria glabrata present. Species abbreviations are listed in Appendix 1. 184 A. Reif R.B. Allen where the influx of partially weathered material decreases. Libocedrus bidwillii and southern rata establish on raised surfaces and logs resulting in widely spaced individuals of tree species so that the Hoheria glabrata community eventually may develop to the Libocedrus bidwillii community group.

3.1.3.2. Plagianthus betulinus community (G) Differential-species of this community were species of the Plagianthus betulinus group (Table 2), including: The main canopy species Plagianthus betulinus; the lianes Rubus schmidelioides and Muehlenbeckia australis which was frequently present in the canopy; the shrubs Aristotelia fruticosa and Pseudopanax anomalus; and Uncinia distans and Corybas trilobus in the ground tier. The adventive herb Prunella vulgaris was frequent (40 %) and was recorded only in this community. Other differential-species from other species groups were Coprosma rotundifolia, Pennantia corymbosa, and Pyrrosia serpens. The diameter of Plagianthus trees sometimes reached 65 cm. The canopy cover ranged between 15 and 40 %, it was low compared to other communities. On stems and branches, there was a dense cover of epiphytic mosses, liverworts and lichens. Their abundance was favoured by the high humidity in the valley bot- toms (fog) and high light conditions under the open canopy. The shrub tier was open with the most frequent species being Pseudowintera colorata, Coprosma ciliata, Olearia ilicifolia, Hoheria glabrata, and Rubus schmidelioides. Polysti-

Plagianthus betulinus community Pb Pb Pb

10m

Sample: Karangarua 28 Ground Cover %: Altitude: 210 m Vascular: 70 Aspect: - Non-vascular: 10 Slope: 0° Litter: 20 Physiography: Terrace Bare Ground: - Parent Material: Alluvium Rock: -

Fig. 11. Plagianthus betulinus community. Stand on silty river terrace. The canopy formed by Plagianthus betulinus is c. 10 m tall. Karangarua River (Cassel Flat), 210 m a. s.1. Species abbreviations are listed in Appendix 1. Steepland conifer-broadleaved hardwood forests of central Westland 185 chum verstitum was the tallest and most common ground cover species, fronds were up to 1.5 m high. Homotoneity in this community was high, and species richness was low (Appendix 3), because the better adapted species, mainly Poly- stichum vestitum, are dominant and exclude other species. Similar forests dominated by Plagianthus betulinus were described by COCKAYNE (1928) and P. WARDLE (1977). The Plagianthus betulinus community was sampled in the Karangarua (Fig. 11) and Copland catchments. This community occurred locally on silty alluvial river terraces on sites subject to cold air drainage. At Cassel Flat, this community was found on a river terrace with a 40 cm thick silt layer over a gravel deposit. Two subdivisions were distinguished, a Fuchsia excorticata subdivision (G1) and an Olearia ilicifolia subdivision (G2). All relevēs of the Fuchsia excorticata subdivision (G1) were from the Karan- garua catchment at an altitude of c. 210 m. This subdivision contained a higher proportion of low altitude species than the Olearia ilicifolia subdivision. Dif- ferential species were Fuchsia excorticata, Pseudopanax crassifolius, Sche f flera digitata, Microlaena avenacea, and Asplenium bulbiferum. Most relevēs of the Olearia ilicifolia subdivision (G2) were from the Copland catchment at an altitude of 450 m. Differential-species were Olearia ilicifolia, Coprosma ciliata, Myrsine divaricata, Coprosma propinqua, Olearia avicenniaefolia, Corybas trilobus, and Hypolepis rugulosa. These species were usually found at higher altitudes. The Plagianthus betulinus community is a seral community (P. WARDLE 1977). Gaps in the canopy on several relevēs were caused by the death of single trees or tree groups. There were few seedlings or saplings of Plagianthus or other tree species in the understorey of this forest. Stands from an elevated river terrace near Welcome Flat appeared to represent a transition from the Plagianthus betulinus community towards the Libocedrus bidwillii community group. Podocarpus hallii and Libocedrus bidwillii were the main tree species, together with some large individuals of Olearia ilicifolia and Griselinia littoralis. The Libocedrus bidwillii was of epiphytic origin. In the shrub tier Pseudowintera colorata, Coprosma foetidissima, Griselinia littoralis, Olearia ilicifolia, Myrtus pedunculata, Podocarpus hallii, Aristotelia fruticosa and Hoheria glabrata were present. Polystichum vestitum remained as an important species in the ground tier. Astelia fragrans, Nertera dichondriaefolia along with fine leaved Uncinia spp., particularly Uncinia angustifolia, were frequent. Such stands were floristically similar to the Libocedrus bidwillii — Myrsi- ne divaricata community, Cyathea colensoi subdivision, Hoheria glabrata type, but, species of the Plagianthus betulinus community were also present. In lowland areas, forest dominated by Plagianthus betulinus can develop towards forest dominated by Dacrycarpus dacrydioides (P. WARDLE 1974, 1980a).

3.1.4. Libocedrus bidwillii community group (H, I) The Libocedrus bidwillii community group was differentiated by the Libocedrus bidwillii species group, including Libocedrus bidwillii in the tree tier; Myrsine divaricata, Archeria traversii, Pseudopanax linearis, Coprosma pseudocuneata 186 A. Reif R.B. Allen and Coprosma astonii in the shrub tier; Uncinia fili formis and Phormium cookianum in the ground tier; and the epiphytic filmy ferns Hymenophyllum rufescens and H. malingii. Hymenophyllum malingii is usually found growing epiphytically on Libocedrus bidwillii (ALLEN 1961; P. WARDLE 1975), although it was also found occasionally on southern rata and once (Camp Creek) on Archeria traversii. The Libocedrus bidwillii community group included the Libocedrus bidwillii — Myrsine divaricata community (H) and the Dracophyllum traversii community (I). The Libocedrus bidwillii community group was largely confined to altitudes above c. 650 m. In this community group, mortality of canopy trees was often intensive over large areas. Species richness decreased with increasing altitude (Appendix 4), partly because the average number of epiphytes decreased from c. 8 per relevē at low altitudes in the Prumnopitys ferruginea community group to c. 2 near treeline.

3.1.4.1. Libocedrus bidwillii-Myrsine divaricata community (cedar-myrsine forest, H) Dominant canopy tree species in the Libocedrus bidwillii — Myrsine divaricata community included southern rata, Libocedrus bidwillii, and Halls totara. Ka- mahi and Quintinia acuti folia were sometimes dominant canopy species also, but declined in size and frequency with increasing altitude. Broadleaf was a widely distributed sub-canopy tree. In the shrub tier Coprosma foetidissima, Pseudowintera colorata, Pseudopanax simplex, Myrsine divaricata, and Archeria traversii were frequently present. The Libocedrus bidwillii — Myrsine divaricata community was usually encountered above the Prumnopitys ferruginea community group, between c. 650 and 850 m altitude (Appendix 5). This community was divided into a Cyathea colensoi subdivision (H1, H2, H3, H4) and a Phyllocladus aspleniifolius subdivision (H5, H6). Their floristic differences were apparently related to variation in site stability, often associated with topographic position. The Cyathea colensoi subdivision was found mainly in unstable landscapes, and was frequent in schist areas. Sites were usually well drained. The forests sampled commonly had an open canopy of large-diametered trees, mostly southern rata. Canopy tree mortality was extensive in some localities. The most frequent species in the shrub tier were broadleaf, Pseudowintera colorata, Pseudo- panax simplex, Pseudopanax linearis, and Coprosma foetidissima. The ferns Cyathea colensoi, Blechnum fluviatile, Blechnum capense minus agg., the grass Microlaena avenacea, and fine-leaved Uncinia spp. were dominant in the ground tier. Southern rata and kamahi usually established as epiphytes, but the dominant canopy species were often infrequent as seedlings or saplings. The Cyathea colensoi subdivision was a high altitude equivalent to the Melicy- tus ramiflorus subdivision found on similar sites in the Prumnopitys ferruginea community group. It was mainly encountered in schist areas (Appendix 6). With- in the Cyathea colensoi subdivision, a Hoheria glabrata type (H1, H2) was differentiated from a Pure type (H3, H4). The Hoheria glabrata type often was found on lower faces and in gullies, where ground surfaces were unstable. The tree tier was low (between c. 8 to 14 m tall), Steepland conifer-broadleaved hardwood forests of central Westland 187 the canopy open, and Pseudowintera colorata, broadleaf, and Coprosma ciliata formed a dense shrub tier. Ground cover was often dominantly Microlaena avenacea. This type had the highest species richness and lowest homotoneity for types in this community (Appendix 3). The Pure type had a higher canopy cover, and the shrub tier was not well- developed. It was found mainly on more stable sites, e.g., upper faces and ridges. It represented a floristic and ecological transition towards the Phyllocladus aspleniifolius subdivision. The Phyllocladus aspleniifolius subdivision (H5, H6; Fig. 12) was encountered mainly on ridges and faces on stable landscapes, e. g., these sites were widespread in the granite areas. Soils on such sites are usually gley podzols (HARRISON 1985a, 1985 b). Species of the Coprosma colensoi group had their main center of distribution in this subdivision. Similar vegetation was described from Granite Hill (J. WARDLE HAYWARD 1970), Mt. Bryan OLynn (COLEMAN et al. 1980) and Westland National Park (P. WARDLE 1977). The Phyllocladus aspleniifolius subdivision is equivalent to the Phyllocladus aspleniifolius subdivisions in the Dacrydium cupressinum community at lower altitudes, and at higher altitudes in the Dracophyllum traversii community. Ha- locarpus biformis, an infrequent species at altitudes below c. 650 m, and Phyllo-

Libocedrus bidwillii – Myrsine divaricata- community M Mu

Cc Sample: Bonar 13 Ground Cover °A: Altitude: 730 m Vascular: 15 Aspect: NW Non-vascular: 15 Slope: 20 ° Litter: 65 Physiography: Face Bare Ground: - Parent Material: Granite Rock: 5

Fig. 12. Libocedrus bidwillii — Myrsine divaricata community. Large diameter (80 cm) Po- docarpus hallii beneath Metrosideros umbellata trees which form a closed canopy. Species abbreviations are listed in Appendix 1. 188 A. Reif R.B. Allen cladus aspleniifolius were co-dominant in the canopy. In Camp Creek, Phyllo- cladus aspleniifolius was absent, yet in adjacent areas of granitic or greywacke substrate it was a dominant species. Southern rata and Halls totara were more frequent and with higher cover in the Phyllocladus aspleniifolius subdivision than in the Cyathea colensoi subdivision. Seedlings and saplings of the dominant tree species were frequent even under an intact canopy, because the understorey was relatively open. This contrasts with the other subdivision where tree seedlings of southern rata, kamahi and Podocarpus hallii were infrequent in old growth forest. There were terrestrial tree seedlings of most tree species, but, it appears that the most successful seedlings that become trees are the ones which established as epiphytes. In canopy gaps, pole stands were sometimes dominated by Quintinia acutifolia, along with kamahi and Phyllocladus aspleniifolius. Gahnia procera, Blechnum capense agg., Uncinia rupestris and Hymenophyllum multifidum were frequent in the ground tier. Homotoneity was high in this subdivision (Appen- dix 3). Between c. 650 and 800 m a. s.1., species of the Prumnopitys ferruginea species group differentiated three Prumnopitys ferruginea subtypes (H1, H3, H5) from Pure subtypes (H2, H4, H6). The Prumnopitys ferruginea subtypes represented a transition towards the lower altitude Prumnopitys ferruginea community group. In these subtypes, particularly on more stable sites, windfall gaps were often filled by dense thickets of Quintinia acutifolia. The slower growing southern rata was initially present in the sub-canopy. Blechnum discolor, a species more frequent in lower altitude forests, sometimes dominated the ground tier. Because low altitude species still were present in these subtypes, species richness was higher than in the equivalent pure subtypes, which were found mainly between 700 and 900 m (Appendix 5). Cedar-myrsine forest showed similar developmental stages to those found in the miro-karamu forest. Light-demanding, opportunistic species like southern rata regenerate from seedlings which establish and grow on sites such as canopy gaps and rocky landslide surfaces (P. WARDLE 1971; STEWART VEBLEN 1982), but also in forests with an open understorey. Southern rata sometimes regenerated by layering (Fig. 13) when large individuals in the canopy topple. These shoots develop to fill the canopy gap created. In central Westland forests this mode of regeneration seemed most developed on flat areas, where the soils are often poorly drained (usually Phyllocladus aspleniifolius subdivision). On these sites, there were often few juveniles of canopy tree species, and regeneration occurred mainly on logs or through layering. In undisturbed old growth forests regeneration of tree species, particularly of Quintinia acutifolia, kamahi, and Libocedrus bidwillii often resulted in mixed- sized stands. However in some stands, seedlings and juveniles of conifers and southern rata were absent. Discontinuous size (age) distributions in Libocedrus bidwillii and Podocarpus hallii have been related to climatic change (HOLLOWAY 1954; P. WARDLE 1978a) and disturbances such as windthrow and landslides (MOLLOY 1969 b; VEBLEN STEWART 1982). On some sites, with time a successional series may develop. For example, with time and continuing soil development, the "transitional" Cyathea colensoi subdivision, Hoheria glabrata type, can develop towards the Pure type and then to- Libocedrus bidwillii - Myrsine divaricata-community

Sample: Hari Hari 106 ,, Cd Cci Cci Mav Lb Ground Cover 0/0: %Cf(epiph.) Lb(dead) Altitude: 825 m Vascular: 70 Ph Aspect: W Non-vascular: 10 Slope: 15 ° Litter: 20 Physiography: Face Bare Ground: - Parent Material: Schist Rock: -

Fig. 13. Libocedrus bidwillii — Myrsine divaricata community. Open canopied stand. Libocedrus bidwillii regenerating on a large g y Y p p ^ g g 00 log.g Metrosideros umbellata layering. SP ecies abbreviations are listed in AppendixpP 1. ^ 190 A. Reif R.B. Allen

Successional changes can also be induced by large-scale tree mortality. In some localities, canopy tree mortality has favoured species of the understorey, e.g., the more shade-tolerant tree species and shrubs like Pseudowintera colorata and Olearia ilicifolia, and can result in a change in the canopy species composition (ALLEN ROSE 1983). The Libocedrus bidwillii — Myrsine divaricata community contained a toposequence which developed from the Cyathea colensoi subdivision, Hoheria glabrata type, towards the Pure type, and then the Phyllocladus aspleniifolius subdivision. This variation parallels a trend from disturbed recent soils to sites which have remained stable for sometime where podzolised soils have often developed (HAR- RISON 1985a, 1985 b).

3.1.4.2. Dacrophyllum traversii community (low statured forest and subalpine shrubland, I) Between 800 and 900 m a. s.1. scattered individuals of Dracophyllum traversii and Dracophyllum longifolium were found in the forests, at lower altitudes in the understorey, at higher altitudes in the main canopy. Other differential-species were the shrubs Olearia colensoi, Senecio benettii, and Dracophyllum uniflorum, and the herbs Chionochloa conspicua, Pterostylis venosa, and Schoenus pauci- florus. Species of the Libocedrus bidwillii species group were present, but more frequently at lower altitudes and on ridges. This resulted in a gradual transition from the Libocedrus bidwillii — Myrsine divaricata community to the Draco- phyllum traversii community (I) which was encountered in the subalpine zone up to c. 1200 m. The vegetation of the subalpine belt is a mosaic based mainly on physiography. On more stable sites, for example ridges and upper faces, taller longer- living tree species were present (Photo 2). On more frequently disturbed sites, seral vegetation, e.g., the Hoheria glabrata community, and alpine vegetation, e. g., tussock grassland, were found. The height and diameter of trees decreased with increasing altitude and the transition between stunted forest and shrubland was gradual. Similar forests from areas in central Westland were described by COCKAYNE (1928), P. WARDLE (1960), J. WARDLE HAYWARD (1970), P. WARDLE (1977), and COLEMAN et al. (1980). BELL (1973) has described small areas of subalpine shrubland with similar species composition from the Owen Range, Nelson. In the Dracophyllum traversii community, a Cyathea colensoi subdivision (I1 and I2), a Pure subdivision (13), and a Phyllocladus aspleniifolius subdivision (I4) were distinguished. On lower faces and gullies, where the substrate is more unstable than on upper faces and ridges species more frequent in seral communities occur. On these sites, a Hoheria glabrata type of the Cyathea colensoi subdivision (I1) contained Coprosma ciliata, C. depressa, Polystichum vestitum, Histiopteris incisa, and species of the Hebe salicifolia- and Blechnum fluviatile group at higher frequency than elsewhere in the Dracophyllum traversii community. The canopy was often open and was dominated by southern rata and Libocedrus bidwillii. Tree species usually regenerated on these lower slopes by establishing on raised surfaces such Steepland conifer-broadleaved hardwood forests of central Westland 191

Photo 2. Dracophyllum traversii community at Camp Creek. With increasing altitude, the size of the trees decreases. The relatively tall Dracophyllum traversii community becomes more restricted to the ridges, and finally is replaced by alpine vegetation. Vegetation of seral character dominates the gullies.

as logs or rocks. Broadleaf was found mainly in the sub-canopy, with diameters up to 50 cm. Species richness was high, and homotoneity low compared to other types (Appendix 3). This community type formed an unusually low timberline at 800-900 m a. s.1. in the Kokatahi catchment. In Westland National Park P. WARDLE (1977) described a "Dracophyllum-Olearia forest" which is floristically similar to the Cyathea colensoi subdivision, Hoheria glabrata type. The Pure type of the Cyathea colensoi subdivision was sampled mostly in areas underlaid by schist (Appendix 6) on sites along ridge crests and upper parts of faces. On some relevēs, southern rata formed relatively pure stands with a sparse understorey (Fig. 14). A Pure subdivision (13) was differentiated with low species richness and high homotoneity (Appendix 3). It was found on stable sites in schist areas, and re-

192 A. Reif R.B. Allen

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presented a transition between the other two subdivisions. This subdivision corresponds to the "tall climax subalpine Dracophyllum-Olearia scrub" sensu P. WARDLE (1977). The Phyllocladus aspleniifolius subdivision (I4) contained species of the Co- prosma colensoi group which occurred most frequently within this subdivision. It was found mainly in localities underlaid by granite or greywacke (Appendix 6), although the gley podzol and shallow soils found on these sites also occurred Steepland conifer-broadleaved hardwood forests of central Westland 193 locally in schist areas (HARRISON 1985a). It was found up to 1200 m a.s.l., and at higher altitudes Halocarpus biformis was sometimes the dominant canopy species, forming relatively pure stands ("Halocarpus biformis-facies"; Fig. 15). The monocotyledons Phormium cookianum, Astelia nervosa, Gabnia procera, and Uncinia fili formis were often dominant in the ground tier.

Hb Lb Dracophyllum traversii community

Pco Sample: Camp creek 181 Ground Cover %: Altitude: 10/.0 m Vascular: 15 Aspect: NW Non-vascular: 20 Slope: 15° Litter: 65 Physiography: Ridge Bare Ground: - Parent Material: Schist Rock: -

Fig. 15. Dracophyllum traversii community. Low statured forest just below shrubland. Dom- inant canopy species is Halocarpus biformis ("Halocarpus biformis-facies"). Species abbreviations are listed in Appendix 1.

In the Dracophyllum traversii community, southern rata and Libocedrus bidwillii often formed a dense canopy, e. g., in the granite areas and at Fox. The trees often had large diameter stems yet tree height declined. With increasing altitude, canopy height declined from c. 14 m to 4 m and Libocedrus bidwillii became an emergent tree (Fig. 16). Lower-statured southern rata, Dracophyllum traversii, D. longifolium, Olearia colensoi, Myrsine divaricata, Griselini,x littoralis and Pseudowintera colorata formed the main canopy. Southern rata was often multi-leadered, "which appears to be induced by ... winter damage" (P. WARDLE 1963 b). At high altitudes, nearly all woody species become multileadered from the base. On exposed sites they become prostrate or procumbent, resulting in so-called "subalpine scrub". Kamahi and Quintinia acutifolia were present at lower altitudes, but usually occurred only as seedling or saplings in the sub- canopy. This community contained a toposequence similar to the one found in the Libocedrus bidwillii — Myrsine divericata community. This toposequence de-

13 Phytocoenologia 16 194 A. Reif R.B. Allen

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/Lb(dead) Sample: Fox 167 Ground Cover %: Altitude: 1030 m Vascular: 30 Aspect: NW Non-vascular: 10 Slope: 10° Litter: 40 Physiography: Face Bare Ground: 10 Parent Material: Schist Rock: 10

Fig. 16. Dracophyllum traversii community. Near the upper limit of Metrosideros umbellata at Fox. The southern rata trees are short statured and have short, stout trunks. Species abbreviations are listed in Appendix 1. veloped from the Cyathea colensoi subdivision towards the Pure subdivision and then the Phyllocladus aspleniifolius subdivision. This variation parallels a similar trend from disturbed recent soils in gullies to podzolised soils on ridge sites (HARRISON 1985a, 1985b).

3.1.5. Halocarpus biformis community group: The Halocarpus biformis- Gahnia procera community (J) Differential-species of this community were species of the Leptospermum scoparium species group, including stunted trees and shrubs of Leptospermum scoparium, Lagarostrobus colensoi, Lepidothamnus intermedius, L. laxifolius, and the herb Abrotanella linearis. The species of the Phyllocladus aspleniifolius species group were frequent. The canopy was uneven in height, with trees of mixed sizes. Logs and stumps of dead trees were often present on the ground, providing sites for tree species to regenerate upon. Dominant canopy trees were Halocar- pus biformis and Phyllocladus aspleniifolius. In the ground tier, Gabnia procera was usually the dominant species. The Halocarpus biformis — Gabnia procera community (Fig. 17) was encountered between 500 and 900 m a.s.l. (Appendix 5). This community represented the transition between tall forest and open pakihi (bog) vegetation dominated by Restionaceae, Cyperaceae and mosses (COCKAYNE 1928; RIGG 1962; P. WARDLE 1977). Most relevēs in this community were from granite areas (Bo- Steepland conifer-broadleaved hardwood forests of central Westland 195

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/) Hb 1, Sm ^ .Q^tiĀ 1►A)f

Ground Cover %: Sample: Camp creek 209 Altitude: 850 m Vascular: 30 Aspect: NW Non-vascular: 40 Litter: 30 Slope: 5° Physiography: Face Bare Ground: - Parent Material: Schist Rock: -

Fig. 17. Halocarpus biformis — Gahnia procera community. Poorly drained site. Open canopied stand dominated by Halocarpus biformis. Sphagnum cristatum present on the ground. Species abbreviations are listed in Appendix 1.

nar Range, Hohohu Range), with only a few from greywacke (Otira) and schist areas (Appendix 6). Mostly these sites were flat areas with impeded drainage. Some relevēs from schist slopes (Karangarua) were on gentle faces or small ridges with moderate or good drainage, sites which have been geomorphically stable in post-glacial times (P. WARDLE 1980a). Relevēs from the Karangarua catchment were on shallow soil above solid bedrock. On these sites soils were extremely leached and infertile (P. WARDLE 1978 b). Soils of this community in Camp Creek were strongly weathered and acidic, including gley podzol and peat (HAR- RISON 1 985 a). Similar communities also occur in other high rainfall areas of South Island, e. g., Fiordland (P. WARDLE 1963 c). Floristic composition and site conditions resemble the "heath forests" from southeast Asia (WALTER 1973; WHITTEN et al. 1984). In the Halocarpus biformis — Gahnia procera community species richness was lowest of all communities described (Appendix 3). Many species become less competitive on account of site infertility, and other species, mainly small herbs not competitive in dense forests, occur with low frequency. A similar decrease of species richness was shown in a locality in South Westland for a vegetation sequence from mixed forest to open bog (MARK SMITH 1975). A Pure subdivision 01) was distinguished from an Empodisma minus subdivision (J2). In the transitional belt from tall forest to stunted shrubland canopy species of the Phyllocladus aspleniifolius- and Leptospermum scoparium group were co-dominant together with species of the Libocedrus bidwillii- and Wein- mannia racemosa species groups. This combination of species groups differentiated the Pure subdivision (J1; Table 2). Libocedrus bidwillii was present as an 196 A. Reif R.B. Allen emergent and southern rata and Halls totara were present in the main canopy. Other species of the tall forest were Dracophyllum longifolium, Olearia colensoi, Archeria traversii, and Coprosma pseudocuneata in the shrub tier, with Blechnum capense minus agg., Astelia nervosa and Abrotanella linearis in the ground tier. On the more extreme sites, in a transition from stunted shrubland to open pakihi (bog) vegetation, species of tall forest communities were absent. A number of small herbs restricted to the most infertile sites (RIGG 1962) differentiated the Empodisma minus subdivision (J2). The group included the ferns and fern allies Gleichenia dicarpa, Schizaea fistulosa, and Lycopodium ramulosum, the orchids Thelymitra venosa and Aporostylis bifolia, the carnivorous plants Dro- sera stenopetala and D. spathulata, and other small herbs like Oreobolus pectinatus and Empodisma minus. On the wettest sites, Sphagnum cristatum (ALLISON CHILD 1971) was sometimes present and on some relevēs up to 75 % of the ground cover was of non-vascular plants. In this subdivision at Lame Duck Flat (Karangarua catchment) stunted silver beech (Nothofagus menziesii) trees were also present. Species richness decreased further from the Pure subdivision towards the Empodisma minus subdivision (Appendix 3). Further studies based on additional data may result in an altitudinal differen- tiation of this community. Lagarostrobus colensoi and L. laxifolius appeared to be more frequent at lower altitudes, Halocarpus biformis and plant species usually found in alpine regions at higher altitudes, and resulted in increasing species richness with increasing altitude (Appendix 4). The Halocarpus biformis — Gahnia procera community represents the most advanced successional stage sampled in this study (similar to P. WARDLE 1980a). The transition between tall forest dominated by hardwoods, stunted forest and shrubland with conifers and open pakihi (bog) vegetation represents a change in a certain set of soil conditions, e. g., a decrease of fertility, which occurred on various sites. A similar sequence has been described by MARK SMITH (1975) from south Westland and by P. WARDLE (1977) from Westland National Park.

3.1.6. Hebe salicifolia community group (K, L) The Hebe salicifolia community group contained two communities, the Raou- lia tenuicaulis community (K) and the Hebe salicifolia community (L). They were usually pioneer communities on primary surfaces and were frequently sampled in schist and greywacke areas, but, were rarely encountered in granite areas (Appendix 6). Differential-species included Hebe salicifolia, Coprosma rugosa, Olearia avicenniaefolia, 0. arborescens, Gaultheria antipoda, Carmichaelia cf. grandiflora, Gaultheria rupestris, and Cordyline indivisa in the shrub tier, and Chionochloa conspicua, Gunnera monoica, Nertera ciliata, and Lycopodium scariosum in the ground tier. Other differentiating species were species of the pratia angulata species group, including many small alpine and subalpine herbs (P. WARDLE 1980c). Where vegetation is removed, some slower growing high altitude species, e. g., of the Dracophyllum traversii species group, can establish but are eliminated when a tall forest develops. Species of the Blechnum fluviatile group were common, and adventive species Steepland conifer-broadleaved hardwood forests of central Westland 197

were frequent. Most occurrences of N-fixing legumes, including two indigenous and two adventive species, were within this community group. There were few juveniles of conifers present on these mineral soils. The presence of species of disturbed sites which are wide-ranging in relation to altitude led to high species richness and low homotoneity (Appendix 3).

3.1.6.1. Raoulia tenuicaulis community (K) Raoulia tenuicaulis is a differential-species of this community along with Poa cockayniana and Trisetum antarcticum agg. Small herbs of the Helichrysum bellidioides species group were frequent, and some had their highest frequency in this community, e. g., Acaena profundeincisa, Epilobium cf. brunnescens, Para-

Photo 3. Raoulia tenuicaulis community. Dominant species is the lichen Stereocaulon ramulosum. There is abundant southern rata seedlings. In the foreground a plant of Celmisia co- riacea. — Fox, 320 m a.s.l., Westland National Park. 198 A. Reif R.B. Allen

Liebe lyallii, Gnaphalium paludosum, and Ourisia caespitosa. Alpine and subalpine species and species of the Hoheria glabrata-, Cyatbea colensoi-, Melicytus ramiflorus species groups were also present. Scattered shrubs of the Hebe salicifolia species group were present. Southern rata and kamahi frequently occurred as seedlings and sometimes as survivors of the last flood. Non-vascular plants were abundant, particularly the lichen Stereocaulon ramulosum, which covered up to 60 % of the ground surface (Photo 3). In many parts of New Zealand, river terraces and flood plains are colonised by various Raoulia species (COCKAYNE 1928; MARTIN 1932; P. WARDLE 1980 a). These species from large patches and mats over recent, unweathered soil, developing on fluvial and fluvio-glacial gravels, alluvium, and fine moraines. These sites are "liable to flooding and, often, complete destruction" (P. WARDLE 1977). The Raoulia tenuicaulis community was sampled over a wide range of altitudes (Appendix 5). As long as sites are periodically flooded, the development of shrubs or trees hindered, and the Raoulia tenuicaulis community is maintained. When streams incise more deeply or rocky landslide-surfaces stabilize succession tends towards the Hebe salicifolia community. This was indicated by the presence of a well- developed shrub tier on some relevēs.

3.1.6.2. Hebe salicifolia community (L) All species groups found in the Hebe salicifolia community also occurred in the Raoulia tenuicaulis community. The typical feature was the absence of the Raulia tenuicaulis species group (Table 2). In this community seral shrubs such as Hebe salicifolia, Olearia avicenniaefolia, Carmichaelia cf. grandiflora, grasses and small herbs, e. g., Chionochloa conspicua, Lycopodium scariosum, and Gunnera monoica dominate. In many parts of South Island similar species com- binations have been described on primary sites (COCKAYNE 1928; MARTIN 1932; MARK et al. 1964; P. WARDLE 1977; ROSE 1985). The Hebe salicifolia community was sampled over a wide altitudinal range (Appendix 5). The differentiating species of this community are pioneer species colonizing primary sites at all altitudes of the forested belt. Climatic factors related to altitude appear to have a minor influence on species composition. Re- levēs in Camp Creek were on recent, unweathered, and free-draining soils of relatively high fertility and uniform texture (HARRISON 1985 a, 1985 b). Typical sites for this community were the upper part of landslide scars which were often bedrock (Photo 4). The lower colluvial deposits of landslides, where large boul- ders and stems of trees were found, were colonized by species of the Melicytus ramiflorus- and Hebe salicifolia species group (e. g., MARK et al. 1964). This species combination differentiates a Melicytus ramiflorus — Carpodetus serratus community, Hebe salicifolia type (A2, A4, A6), which floristically and ecologi- cally represents the transition between the Hebe salicifolia — and the Melicytus ramiflorus community group. A floristically similar "open shrubland on steep slips and talus" was described by P. WARDLE (1977). A Helichrysum bellidioides subdivision (L1, L2, L3) was distinguished from a Pure subdivision (L4, L5; Fig. 4). Steepland conifer-broadleaved hardwood forests of central Westland 199

Photo 4. Steep face, bearing different successional stages of the Hebe salicifolia community and more developed forests. — Karangarua catchment, Westland National Park.

The Helichrysum bellidioides subdivision was differentiated by species of the Helichrysum bellidioides species group. On some relevēs there was much bare ground and rock, covered with mosses (e. g. Rhacomitrium lanuginosum, Poly- trichum juniperinum), liverworts (e.g. Anthoceros spec.), and particularly lichens (mostly Stereocaulon ramulosum). These non-vascular plants were often the most evident species. The small herbs Helichrysum bellidioides and Nertera ciliata were dominant on some relevēs, and seedlings of herbaceous, shrub, and tree species were present. Adventive species were most frequent in this subdivision, which was floristically similar to the Raoulia tenuicaulis community (Table 2). In the Pure subdivision (L4, L5), species of the Helichrysum bellidioides species group were absent. The cover of southern rata, kamahi, Quintinia acutifolia and the shrubs of the Hebe salicifolia species group was higher than in the Heli- chrysum bellidioides subdivision. Up to c. 800 m a.s.l., species of the Prumnopitys ferruginea species group (e.g., Coprosma lucida, Blechnum discolor) and other low altitude species differentiated a Blechnum discolor type (L1, L2, L4; Appendix 5) from a Pure type (L3, L5). These species declined in frequency with increasing altitude. The Pure types were sampled up to c. 1000 m a.s.l. Cortaderia richardii differentiated a Cortaderia subtype (L1) which was encountered mainly on silty stream escarpments. A similar community was described from similar sites by P. WARDLE (1980a). When landslides occur primary succession starts with the Hebe salicifolia community, Helichrysum bellidioides subdivision. Southern rata, kamahi, and Quintinia acuti folia, species dominating tall statured forest, usually established 200 A. Reif R.B. Allen along with species of the Hebe salicifolia species group (P. WARDLE 1980a; STEWART VEBLEN 1 982). In areas of extensive forest dieback, e.g., parts of the Kokatahi river catchment, there were few southern rata seedlings present on landslide surfaces. It appears that dieback of southern rata has locally removed the seed source (ALLEN ROSE 1 983 ). With time, a dense shrub tier develops dominated by Hebe salicifolia, Carmi- chaelia cf. grandiflora, Coprosma rugosa, Quintinia acuti folia, southern rata, kamahi, Olearia avicenniaefolia and occasionally Cordyline indivisa (Photo 5). Under these conditions, the small herbaceous species of the Helichrysum bellidioides group are no longer competitive. Taller herbs become dominant, the Pure subdivision (L4, L5) replaced the Helichrysum bellidioides subdivision, and was associated with a decrease in species richness (Appendix 3). Following this the regenerating forest species (southern rata, kamahi, Quintinia acuti folic) become dominant. Most relevēs of a "transitional stage (L6)" were from steep sloped upper parts of landslide surfaces. In this transitional stage towards "evensized" forests (described in the miro-karamu forest and cedar-myrsine forest), the shrubs of the Hebe salicifolia group become replaced. Species richness decreases further, and homotoneity remains low (Appendix 3). Thinning occurs in the dense pole stands. Where there is repeated disturbance stages with the initial character (L1, L2, L3) were retained, and shrubs remain small.

Photo 5. Hebe salicifolia community at Fox. Steep landslide surface with seral vegetation dominated by 2 m tall Cordyline indivisa. — Fox catchment, Westland National Park. Steepland conifer-broadleaved hardwood forests of central Westland 201

3.2. Patterns of forest development Local variation in composition of plant communities in the conifer-broadleaved hardwood forests of central Westland was related mainly to an altitudinal gradient and to patterns of forest development. The various forms of disturbance, particularly of soils, resulted in spatial "discontinuity" in these forests compared with altitude (DANSEREAU 1964). This is consistent with previous studies (J. WARDLE HAYWARD 1970; P. WARDLE 1977, 1980a). These dominant gradients were used to construct a two dimensional representation of these forests (Fig. 18). The axis labelled "Development" was constructed from the floristic relationships between communities. This axis is largely a reflection of time. As the rate of development varies with environmental conditions (P. WARDLE 1980a; SMITH LEE 1984), we have not fitted a time scale. Although in Fig. 18 arrows are drawn to indicate typical patterns of forest development, such a sequence is frequently impeded by further disturbance. Catastrophic disturbance may initiate a new sequence, or less severe disturbance may halt development. The two dimensional representation of these forests provides a generalized frame- work to consider floristic relationships of communities. These will be considered chronologically. In central Westland high natural erosion rates lead to frequent disturbances which expose fresh mineral surfaces. These are a consequence of erosion processes such as landslides, downcutting of streams, and alluvial deposition. The removal of vegetation, including long-lived canopy trees, creates sites where the Raou- lia tenuicaulis — and Hebe salici folia communities were found. Such sites favour species which are:

— Light-demanding small herbs unable to compete in forests (GRIME 1979). These include Lycopodium scariosum, Gunnera monoica and Pratia angulata. Many have their main center of distribution in the alpine zone. Additionally, adventive species, mostly short-lived, are a minor component in some early successional communities, e. g., Cirsium palustre, Senecio jacobaea, Holcus lanatus, Digitalis purpurea and Hypochoeris radicata. These "ruderals" (GRIME 1979) are virtually absent from the tall forest communities (Table 2). Adventive species are a major feature in the vegetation of many areas of New Zealand (ALLEN 1937; GODLEY 1975), but have typically had little success in invading the indigenous forests. — Rapid pioneer species with relatively short life spans (WHITE 1979), e.g., many fast growing species of scrub-hardwoods (P. WARDLE 1963 b), including Hebe salici folia, Olearia avicenniaefolia and Carmichaelia cf. grandiflora. These species enter the pioneer communities in the earliest developmental stages when competitive pressures are low (E GLER 1976). — Woody species which normally are found near timberline, e.g., Dracophyllum traversii and D. longi folium. These species germinate and grow as long as light conditions are favourable. With time, they are overtopped by taller forest trees. — Opportunistic longer-living forest species such as kamahi, Quintinia acuti folia and southern rata. Southern rata is able to establish abundantly on these sites, but in tall forests is often restricted to raised surfaces. Kamahi and Quintinia acutifolia establish also in dense old growth forests.

N Dracophyllum traversii community 0 N Hoheria glabrata Cyathaea colensoi subdivision --1 --? - -0► community Pure sub- aspleniifolius Hoheria glabrata division Pure type subdivision 1 typeYP YP Hebe salicifolia ommunity group 4■41111110- Halocarpus Hebe salicifolia Libocedrus bidwilli-Myrsine divaricata community community; biformis-Gahnia a Raoulia tenuicaulis procera community CY athaea colensoi subdivision Phyllocladus community aspleniifolius 1=1 Hoheria glabrata Pure type subdivision type Pure sub- Empodisma = minus division subdivision —-- ^ -- Plagianthus betulinus ^ community PrumnopitysP ferru9 urea - Coprosma lucida community Dacrydium cupressinumP community ,

Melicytus ramif torus - Melicytus ramiflorus Pure sub- Carpodetus serratus subdivision division Melicytus Phyllocladus commu nity ramiflorus Puresub - aspleniifolius subdivision division subdivision

Dacr Ycarpus -1111•11r 7 MID MIMI dacrydioides community

De v el o P m e n t

Fig.S Successional stages8 of the steeplandp conifer-hardwood forests of central Westland at different altitudes. Steepland conifer-broadleaved hardwood forests of central Westland 203

With time, the tree species overtop the herbaceous and shrub species. The subsequent elimination of species such as Hebe salicifolia, Carmichaelia cf. grandiflora and Chionochloa conspicua (Hebe salicifolia species group) along with the elimination of the high altitude woody Dracophyllum-species at low altitudes accounts for the transition of the Hebe salicifolia — and Raoulia tenuicaulis communities to taller statured forest communities. These successional communities develop towards young, even-sized stands. These developmental stages are illustrated by different communities at different altitudes: At low altitudes, the Prumnopitys ferruginea — Coprosma lucida community develops. And at higher altitudes, succession results in the communities of the Liboce- drus bidwillii community group. Without further disturbance, the even-sized forests develop to forests with mixed-sized trees. Kamahi, Quintinia acuti folic, and on less fertile sites southern rata regenerate also in tall old growth forest. As a result there is only one canopy hardwood tree species, Elaeocarpus dentatus, which fulfills the exclusive func- tion of differentiating more advanced communities from distinct successional stages. Because all relevēs located in the Plagianthus betulinus — and the Dacrycarpus dacrydioides community were in tall statured forest it was not possible to describe the succession leading to their establishment. By overlapping of species groups a succession from the Plagianthus betulinus community towards the Libocedrus bidwillii — Myrsine divaricata community, and from the Dacrycarpus dacrydioides community towards the Dacrydium cupressinum community is indicated (Fig. 18). The Hoheria glabrata — and the Melicytus ramiflorus — Carpodetus serratus community were found at different altitudes on recently disturbed sites containing fine earth, e.g., canopy gaps, talus of landslides, and gullies. When the frequency of disturbance decreases, these communities can develop towards floristically related subdivisions of the communities of the Prumnopitys ferruginea - and Libocedrus bidwillii community group. These again are floristically similar to community types formed by primary succession. Such a process is indicated, e.g., by overlapping of the Melicytus ramiflorus species group with the Prumno- pitys ferruginea species group (in D1, D2, D3, El, E2), and by overlapping of the Hoheria glabrata species group with the Libocedrus bidwillii species group (in H1, H2, I1). Typically conifers seldom establish on freshly exposed mineral surfaces. Based on different frequencies in the different communities they can be regarded as species characteristic of forest on more developed soils. This contrasts with the suggestion of DANSEREAU (1964) that there is a "lack of subclimax trees". Where soil disturbance is periodic, the hardwoods are maintained. Without further disturbance, conifers become more prominent in the forests, and a long- term succession can result in communities (Dacrydium cupressinum community) and subdivisions (Phyllocladus aspleniifolius subdivisions) differentiated by conifers. Similar associations of species of the Melicytus ramiflorus species group with recently disturbed more fertile soils, and of the Phyllocladus aspleniifolius species group with developed, leached and more infertile soil have been made in a number of areas in central Westland (P. WARDLE 1963 c, 1964, 1969; J. WARD- 204 A. Reif R.B. Allen

LE HAYWARD 1970) and elsewhere (SMITH LEE 1984; J. WARDLE 1984; ROSE 1985). Without disturbance soils become leached and are mainly gley podzols. Tree height decreases, trees become more and more stunted, and the canopy cover decreases. In a "regression", forest develops to the low statured shrubland of the Halocarpus biformis — Gahnia procera community. CUTLER (1960) related a similar shift of dominant canopy species to the degree of soil development. For example, "rata/kamahi/rimu forest" occurred on podzolised yellow-brown earths on rolling hilly slope, "rimu forest" on gley podzols, and "rimu/silver pine forest" and manuka scrub on peaty gley-podzols. The time period for such a development can vary, depending on local site conditions. It ranges from c. 1300- 3000 years on old river terraces in South Westland (SMITH LEE 1984) to c. 22 000 years at Franz Josef Glacier, central Westland (STEVENS WALKER 1970), and to c. 100 000 years in Westland National Park (P. WARDLE 1980a). But, the earlier parts of the longer sequences occurred under glacial climates and vegetation. The sequence of development depicted in Fig. 18 occurs in conifer-broadleaved hardwood forests where the site is not subject to further disturbances. This does not usually occur. The frequency of catastrophic disturbance in these forests is often related to landscape stability. As a consequence it may be ex- pected that the frequency of communities (and subunits) will vary between the localities sampled. The most widespread geological substrates, schist and granite,

Photo 6. In schist areas, disturbance of soil and vegetation is so frequent that succession results in a mosaic of different developmental stages. — Kokatahi River. Steepland conifer-broadleaved hardwood forests of central Westland 205 are chemically similar, but, tectonic activity and degree of rock fracture differ considerably. In schist areas, disturbances of soil and vegetation are frequent, resulting in a mosaic of sites. For instance, many soils of Camp Creek, a schist locality, are less than 500 years old (HARRISON 1985 a). In schist areas, seral communities and forests differentiated by species of the Melicytus ramiflorus- and Hoheria glabrata species group were frequently found. But, on locally stable sites, e.g., ridges and spurs, soils may be as old as 4000-5000 years (HARRISON 1985a), and on such sites the Phyllocladus aspleniifolius subdivisions and the Halocarpus biformis- Gahnia procera community can be found. Because of edaphic variation often related to topography, e.g., a gradient of frequent soil disturbance in gullies and at the base of slopes towards less frequent disturbance on ridges and faces, several forest community types can occur in an ecological series, resulting in a vegetation pattern (Photo 6). In areas underlain by granite, e. g., the Hohonu and Bonar Ranges, the canopy was more uniform, with few areas of seral vegetation (Photo 7). Soils were more developed, and the Phyllocladus aspleniifolius subdivisions of the tall forests communities were found frequently. At low altitudes, the Dacrydium cupressinum community was dominant, and the Prumnopitys ferruginea — Coprosma lucida community frequently found on schist was rare. Stands with young, even- sized trees were usually absent, and regeneration mostly occurred in small-scale windfall gaps.

Photo 7. In landscapes underlain by granite, sites are more stable and vegetation cover is more uniform than in schist areas. — Granite Hill. 206 A. Reif R.B. Allen

3.3. Patterns of forest dieback Mortality of canopy trees, including individuals of southern rata, kamahi, Fuch- sia excorticata, Libocedrus bidwillii and Podocarpus hallii, has been described as a feature of the conifer-broadleaved hardwood forests (CHAVASSE 1955; HOLLO- WAY 1959; P. WARDLE 1978a). The large-scale differences in landscape stability and vegetation can be related to different intensities of canopy mortality. In schist areas, tree mortality was high, and 24 % of all relevēs of the tall forests at low altitudes (Prumnopitys ferruginea community group), and 35 % of all rele- vēs of the tall forests at high altitudes (Libocedrus bidwillii community group) showed signs of mortality of three main canopy species, southern rata, Podocar- pus hallii and Libocedrus bidwillii. In granite areas, tree mortality was much less than in schist areas, and only 10 % of all relevēs of the Prumnopitys ferruginea community group and 11 % of the Libocedrus bidwillii community group showed signs of tree mortality. In schist areas, canopy mortality can be extensive (Photo 8). Areas of up to tens of hectares can be affected (ALLEN ROSE 1983), and mortality occurs over a wide range of altitudes (COLEMAN et al. 1980; ALLEN ROSE 1983). The major- ity of the relevēs of the Prumnopitys ferruginea- and the Libocedrus bidwillii community group in schist areas belonged to subdivisions containing species groups of early successional stages (e. g., Melicytus ramiflorus-, Hoheria glabrata species group). In granite areas such forest was of limited distribution, and found on disturbed sites, e.g., on unconsolidated substrates probably resulting from earth- quakes, and on glacial till. Mortality was more frequent in forest containing species of early successional stages than in forest containing species of the Phyllocladus aspleniifolius species group (Appendix 2). Such a pattern was evident in comparing granite and schist areas, but, even when both types of forest were adjacent mortality of trees followed the same pattern. In Camp Creek, Halocarpus biformis shrubland on infertile sites (mainly I4) containing southern rata was little affected by tree mortality, whereas there was extensive mortality in the adjacent forests on the more disturbed sites (mainly H 1-4 and I 1-3). However , not all relevēs of forest in schist areas showed canopy mortality (Appendix 2). In some sites trees may have died and decayed so that mortality was not recorded. E.g., in the Kokatahi and Fox catchments southern rata stems were usually standing and relatively intact after being dead for 30 years, whereas, kamahi trees have more often collapsed and partially decayed in this time (ALLEN ROSE 1983; COLEMAN et al. 1980). The scrub-hardwoods Fuchsia excorticata and Hoheria glabrata also decay relatively fast. E.g., dead Fuchsia stems were still standing in the Fox Valley in 1964 (P. WARDLE, pers. comm.), whereas, they completely have decayed until 1982. Another example is that young, even-sized stands dominated by southern rata remained healthy (CHAVAS- SE 1955; P. WARDLE 1971), even when they were surrounded by dieback forest (Photo 1). Often tree mortality has been attributed to browsing by the arboreal brush- tailed possum (FITZGERALD WARDLE 1979; COLEMAN et al. 1980; BATCHE- LER 1983; COLEMAN et al. 1985), and mortality patterns have been related to their colonisation of an area (BOERSMA 1974; PEKELHARING REYNOLDS Steepland conifer-broadleaved hardwood forests of central Westland 207

Photo 8. Synchronous mortality of southern rata (Metrosideros umbellata). In the understorey dense Olearia ilicifolia. — Kokatahi.

1983). The importance of other factors has been considered (CHAVASSE 1955; STEWART VEBLEN 1982) and VEBLEN STEWART (1982a) and MUELLER- DOMBOIS (1986) support the hypothesis that much of the mortality is related to senescence of even-aged stands. Older trees have a relatively large proportion of respiratory tissue, resulting in low photosynthetic carbon gain, and it appears they may be less able to replace leaves after defoliation (PAYTON 1983, 1985). Stand structure, and the related tree vigour, may be used to explain the healthy young even-sized stands. However, stands of dead trees have a wide range of diameters, and probably ages (COLEMAN et al. 1980; ALLEN ROSE 1983). Because of the relationship between mortality and community types found in this study it appears additional explanations are required to describe mortality patterns. 2 08 A. Reif R.B. Allen

A plausible hypothesis for tree death is that browse pressure by brush-tailed possums is different in different community types. It appears that localities and community types containing early successional species provide a more suitable habitat for possums. In schist areas, community diversity is higher and early successional species are more frequent, than in granite areas. A more diverse vegetation "... provides a wide range of food sources and feeding niches" (COLEMAN et al. 1980). It can be noted that young, even-sized forest has low species richness. Additionally, in granite areas soils are less fertile, and nutrient poor communities do not support high levels of herbivory (e. g., BRYANT et al. 1983; CHAPIN et al. 1986). This is consistent with the absence of extensive canopy dieback from the Phyllocladus aspleniifolius subdivisions, these subdivisions were frequently found in granite localities. In these localities, habitat conditions appear less suitable for brush-tail possums. Peak population numbers in schist areas were higher than in granite areas (C. PEKELHARING, pers. comm.). It is suggested mortality reflects sites most suited to the introduced brush-tail possum, resulting in an increased browse pressure on the dominant canopy species.

4. Conclusion

The conifer-broadleaved hardwood forests of central Westland are diverse compared with the extensive beech forests found in other parts of South Island (c. f. J. WARDLE 1970, 1984). In this study, relevēs from the broad range of site conditions found in central Westland were classified into a hierarchical system, using the approach of BRAUN -BLANQUET. The grouping of forest species into ecological species groups was regarded as difficult, mainly because of their relative great ecological amplitude (DANSEREAU 1964). The success of this floristic classification, along with earlier studies (e. g., J. WARDLE HAYWARD 1970) indicates that DANSERAU (1964) underestimated the indicator value of some plant species in these forests. The species groups determined in this study may be applied to other areas, and may be particularly useful in comparing the conifer-broadleaved hardwood forests of central Westland with those found in other parts of South Island. The communities (and subunits) determined in this study were related to various environmental conditions and patterns of forest development. Altitude is a complex gradient and has often been related to species composition of montane forests (FRANZ 1979; MARK SANDERSON 1962; WALTER BRECK- LE 1983). In this study topographic position could often be related to species composition. Because of the high erosion rates and rainfall in the study area topographic position was related to soil disturbance and fertility. This contrasts with forests in low rainfall regions (< 500 mm) where topographic position has been considered to reflect moisture conditions. Although it is difficult to isolate these two factors both are probably important. The successional patterns described in the conifer-broadleaved hardwood forests of central Westland suggest that a combination of alternative succession theories operate. Emphasis that succession can be viewed as a population process (EGLER 1954; DRURY NISBET 1973; CONNELL SLATYER 1977; PEET Steepland conifer-broadleaved hardwood forests of central Westland 209

CHRISTENSEN 1980) is consistent with patterns of forest development described in this paper, particularly the short-term patterns. However, certain successional patterns appear associated with environmental changes, dominantly in soil chemistry and morphology. These are usually associated with longer term successional trends (STEVENSEN 1968; WALKER et al. 1981). However, because of high rainfall in the study area, rapid leaching can modify soil conditions within a generation of some tree species (< 500 years).

Acknowledgements. We thank U. BENECKE, Christchurch, for help and support in all phases of this work. We also are grateful to J. ABRAHAM, P. CROMARTY, R. MORISON, S. PEARSE, and K. PLATT for help with the field sampling; to E. EDGAR and K. PLATT for help with the identification of species; to G. HALL for assistance with the data analysis; and to M. McBRIDE and W. SÖLLNER for drawing the figures. U. JENSEN, J. ORWIN, E.-D. SCHULZE, J. WARDLE, P. WARDLE, and 0. WILMANNS made useful criticisms on the manuscript. This research was supported by New Zealand Forest Service, Christchurch, and by Deutsche Forschungsgemeinschaft (DFG), Bonn.

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Addresses of the authors: Dr. A. REIF, Lehrstuhl für Pflanzenökologie der Universität, Postfach 101251, D-8580 Bay- reuth. R.B. ALLEN, Forestry Research Centre, Forest Research Institute, P.O. Box 31011, Christ- church, New Zealand.

Appendix 1: Nomenclature of species

Except for those listed below species were named after "Flora of New Zealand", Vol. I and II (ALLAN 1961; MOORE EDGAR 1970). Nomenclature of fern species follows BROWNSEY et al. (1985). Exceptions are some revised fern genera, their nomenclature follows the provisional "checklist of New Zealand pteridophytes" (D. S.I.R., Lincoln): — Blechnum capense agg., includes B. procerum and Blechnum lati folium; — Blechnum capense minus agg., includes B. minus (R. Br.) Ettingh. and a few similar varieties; — Hypolepis rugosula (Labill.) J. Smith; — Tmesipteris tannensis agg., includes T. elongata, T. lanceolata, T. sigmati folia and T. tannensis. Shrubs and trees contained in "Trees and Shrubs of New Zealand" (POOLE ADAMS 1980). The conifers were named after QUINN (1982), the genera Pseudopanax after ED- GAR (1973), Epilobium spp. after RAVEN RAVEN (1976), Acaena profundeincisa after MacMILLAN (1983), Gnaphalium spp. (sect. Euchiton) after DRURY (1972). The revised names of Pseudognaphalium luteo-album (L.) Hillard et Burtt (= Gnaphalium luteo-album), of Brachyglottis bellidioides (Hook. f.) Nordenstam (= Senecio bellidioides), Scirpoides no- dosa (Rottb.) Sojak, Isolepis habra (Edgar) Sojak (= Scirpus habrus), and Sisyrinchium pul- chellum (R. Br.) Muell. (= Libertia pulchella) are contained in EDGAR CONNOR (1983). Hierochloe is named after ZOTOV (1973), Rytidosperma after CONNOR EDGAR (1979), Deyeuxia avenoides and the genus Microlaena after CHEESEMAN (1925), and Corybas acuminatus M. Clements et Hatch (= C. rivularis sensu Cheesem.) and C. rivularis (A. Cunn.) Reich-b.f. (= C. orbiculatus sensu L.B. Moore 1970) after CLEMENTS HATCH (1985). The Poaceae, subfamily Arundinoideae were named after ZOTOV (1963). Adventive plants (Table 2) were named after TUTIN et al. (1964-1980; = Flora Euro- paea, vol. I—V). A few species not yet described have provisional names used by D.S.I. R., Lincoln, so Blechnum "black spot", Agrostis perennans and A. "canina". Profile diagrams use the following abbreviations of species names: Ab = Asplenium bulbiferum Csm = Cyathea smithii Af = Asplenium flaccidum Dc = Dacrydium cupressinum An = Astelia nervosa Dl = Dracophyllum longifolium As = Aristotelia serrata Ds = Dicksonia squarrosa At = Archeria traversii Dt = Dracophyllum traversii Bc = Blechnum capense agg. Fe = Fuchsia excorticata Bd = Blechnum discolor Gl = Griselinia littoralis Cc = Cyathea colensoi Gp = Gahnia procera Cci = Coprosma ciliata Ha = Hedycarya arborea Cco = Coprosma colensoi Hb = Halocarpus biformis Cd = Coprosma depressa Lb = Libocedrus bidwillii Cf = Coprosma foetidissima Ls = Lastraeopsis superba Cl = Coprosma lucida Ma = Muehlenbeckia australis Cp = Coprosma pseudocuneata May = Microlaena avenacea Cr = Coprosma rotundifolia Md = Myrsine divaricata Cs = Carpodetus serratus Mp = Myrtus pedunculata 216 A. Reif R.B. Allen

Mr = Melicytus ramiflorus Pf = Prumnopitys ferruginea Mu = Metrosideros umbellata Ph = Podocarpus hallii Nc = Pseudopanax colensoi P1 = Pseudopanax lineare Oc = Olearia colensoi Ps = Pseudopanax simplex 01 = Olearia lacunosa Pv = Polystichum vestitum Pa = Phyllocladus aspleniifolius Qa = Quintinia acutifolia Pan = Pseudopanax anomalus Ra = Rumohra adiantiformis Pb = Plagianthus betulinus Rs = Ripogonum scandens Pc = Pseudowintera colorata Sb = Senecio bennettii Pcr = Pseudopanax crassifolius Sc = Sticherus cunninghamii Pco = Phormium cookanum, Sd = Schefflera digitata Pd = Pittosporum divaricatum Wr = Weinmannia racemosa Pdi = Phymatosorus diversifolius

List of common names: Broadleaf (Griselinia littoralis) Hinau (Elaeocarpus dentatus) Kahikatea (Dacrycarpus dacrydioides) Kamahi (Weinmannia racemosa) Karamu (Coprosma lucida) Manuka (Leptospermum scoparium) Miro (Prumnopitys ferruginea) Rimu (Dacrydium cupressinum) Silver beech (Notpo fagus menziesii) Southern rata (Metrosideros umbellata) Steepland conifer-broadleaved hardwood forests of central Westland 217

Appendix 2: Canopy mortality and communities

Table 3 presents a summary of the mortality data for three tree species in the Prumnopitys ferruginea-, Libocedrus bidwillii- and Halocarpus biformis community groups (C, D. E, H, I, J), and includes all samples other than those in the Fox catchment. Data are presented only for these relevē groups where Metrosideros umbellata, Podocarpus hallii or Libocedrus bidwillii were dominant trees. These three species were selected because their mortality has often been noted (CHAVASSE 1955; J. WARDLE 1974; COLEMAN et al. 1980; BATCHE- LER 1983; PEKELHARING REYNOLDS 1983). The stems of these species appear to remain intact for a long time. In the Kokatahi and Fox catchments southern rata stems were usually standing and relatively intact after being dead for 30 years (COLEMAN et a1.1980; ALLEN ROSE 1983). The frequency of dead trees on those relevēs containing either dead or live individuals of a species were calculated for each relevē group. The results only discuss patterns where these species were present on more than five relevēs, either live or dead, in a relevē group. Releves where these three species were totally absent were excluded from analysis.

Table 3. Percent frequency of mortality of the three main canopy species Metrosideros umbellata, Podo carpus hallii and Libocedrus bidwillii.

Community type Metrosideros umbellata Podocarpus hallii Libocedrus bidwillii

C1 0 0 — D1 0 0 — D 2 14 0 0 D 3 0 10 0 D 4 100 0 — D 5 0 13 — D 6 7 9 — D 7 7 14 — D8 0 5 8 E 1 38 17 — E 2 8 10 0 E 3 38 43 — E 4 21 14 — H 1 44 44 22 H 2 33 0 33 H 3 8 16 6 H 4 0 33 22 H 5 7 10 20 H 6 10 0 0 I 1 48 36 24 I 2 8 29 11 I 3 0 33 50 I4 0 0 0 J1 0 0 0 J2 0 0 0

218 A. Reif R.B. Allen

Appendix 3: Species richness and homotoneity related to communities

Table 4 shows species richness and homotoneity of the 43 community types in four para- meters. Using all relevēs of a community, species richness (the average number of species per relevē) and homotoneity were calculated. Homotoneity values (cH) were calculated as ratio between the frequencies of species occurring in more than 60 % of the relevēs to the average number of species, and were corrected, respecting the differences in species numbers of the relevēs (MORAVEC 1972). Based on 10 systematically selected reeves of each community type when available, the total number of species, and the ratio between the number of species on eight to ten over the number of species on one to three of ten systematically selected relevēs are given. The abbreviations of the community types used in Table 4 can be deci- phered at the bottom of the summarized frequency table (Table 2).

Table 4. Average and total number of species and homotoneity of the relevē groups.

Community Number Average number of Homotoneity Total Ratio of the type of relevēs species, standard (sensu number species on 7 (n) deviation MORAVEC of spe- relevēs to the 1972) cies on number of 10 re- species on levēs 3 relevēs

Melicytus ramifl. - Carpodetus serr. community: Al 72 28.0 ± 7.1 25.2 91 0.17 A2 7 25.6 ± 7.8 19.3 - - A3 26 25.3 ± 6.0 22.2 85 0.14 A4 16 28.6 ± 5.0 29.2 96 0.13 A5 14 24.4 ± 4.3 27.8 75 0.16 A6 23 25.5 ± 7.4 18.7 97 0.11 Coriaria arborea community: B1 8 26.4 ± 4.5 39.9 - - Dacrycarpus dacrydioides community: Cl 14 3 6.9 ± 7.4 34.4 100 0.21 Dacrydium cupressinum community: D1 9 30.1 ± 4.8 40.0 67 0.43 D2 60 31.0 t 6.3 32.4 69 0.34 D3 12 30.1 ± 3.3 41.3 70 0.28 D4 12 28.2 ± 2.6 47.4 - - D5 25 25.5 ± 5.0 38.6 90 0.22 D6 15 24.1 ± 4.8 39.8 84 0.25 D7 15 26.7 ± 4.7 37.9 75 0.24 D8 22 28.6 } 4.7 40.7 73 0.31 Prumnopitys fern. - Coprosma luc. community: El 54 28.1 ± 5.0 29.5 91 0.10 E2 64 30.3 ± 62. 31.5 87 0.21 E3 10 23.7 ± 3.7 40.6 66 0.25 E4 48 21.5 ± 5.3 32.1 64 0.17 Hoheria glabrata community: Fl 16 35.3 ± 5.9 31.4 124 0.10 F2 24 31.2 ± 6.7 24.6 89 0.14 Plagianthus betulinus community: G1 7 24.6 ± 2.4 41.7 - - G2 11 23.0 ± 2.9 46.0 63 0.32 Steepland conifer-broadleaved hardwood forests of central Westland 219

Table 4. cont.

Libocedrus bidw. - Myrsine div. community: H1 32 33.9 ± 10.4 24.6 125 0.12 H2 7 22.3 ± 8.2 24.3 - - H3 70 27.3 ± 4.8 28.1 76 0.22 H4 16 26.7 ± 5.4 38.7 76 0.25 H5 30 27.3 ± 4.3 43.3 62 0.42 H6 11 26.4 ± 4.3 57.6 64 0.50 Dracophyllum traversii community: I1 28 29.1 ± 6.9 35.0 78 0.21 I2 20 24.0 ± 5.0 48.9 71 0.19 I3 11 19.7 ± 3.9 55.4 41 0.60 I4 71 27.1 ± 4.4 43.4 58 0.48 Halocarpus bif. - Gahnia proc. community: Ji 15 20.1 5.9 29.1 54 0.10 J2 25 18.0 4.4 20.1 62 0.11 Raoulia tenuicaulis community: K1 19 34.7 9.0 8.9 151 0.04 Hebe salicifolia community: Li 23 30.0 8.3 11.7 106 0.07 L2 56 31.8 8.9 11.0 107 0.06 L3 29 28.2 6.8 5.5 128 0.02 L4 20 24.3 5.5 14.8 94 0.04 L5 6 23.2 6.0 - - - L6 14 22.0 5.1 14.1 84 0.06 220 A. Reif R.B. Allen

Appendix 4: Species richness patterns in relation to altitude

Table 5. Average number of species per relevēs and standard deviation in relation to altitude. P = significance level, Spearmans rank correlation.

Altitude Vegetation type (m a.s.l.) Primary Seral "scrub Tall forest Vegetation on successional hardwood" communities infertile sites vegetation communities (C, D, E, H, I) ("heath forest", (K,L) (A,B,F,G) J)

1001-1100 35.0 33.0 ± 6.0 25.0 ± 5.0 - 901-1000 26.2 ± 3.3 27.5 ± 8.5 26.3 ± 6.4 23.0 801- 900 29.8 ± 6.5 32.2 ± 6.1 27.0 ± 6.6 23.0 ± 6.0 701- 800 28.5 ± 9.1 30.2 ± 7.8 28.2 ± 6.6 18.5 ± 5.5 601- 700 30.0 ± 9.0 29.6 ± 8.2 26.3 ± 7.0 17.3 ± 2.8 501- 600 28.9 ± 9.4 25.5 ± 6.4 26.9 ± 6.8 16.0 401- 500 26.7 ± 10.7 27.3 ± 6.3 24.5 ± 5.5 15.7 301- 400 30.4 ± 7.1 26.4 ± 7.0 27.8 ± 5.6 - 201- 300 32.3 ± 8.0 24.8 ± 4.7 30.6 ± 6.0 - 101- 200 31.0 ± 4.6 28.9 ± 6.3 31.5 ± 5.2 - 0- 100 - 35.7 ± 10.3 35.3 ± 9.8 -

P - - 0.02 0.01

►^ •• y n 0 0^ o P.. a 5 ‘q^ 5 1100 - ^ a n ^ 0 ^ " 1000- ^^ ,.. nrt a I-,c m- 900- o eb ^► O ,.t, ^ ō ^ Q 800 - ^ ►^ o o a. ^^° n 700-700-. ^ o 600 - p.«, a 5- w • 500- !Dt. 0 400-`

^ 300- ►... a. ^ ^ 200- ,.. ^ 100 - fli I ^ t O• P a. 0 0 Al A2 A3 A4 A5 A6 B1 C 1 D1 D2 03 04 D5 D6 D7 D8 El E2 E3 E4 0^ E., 100 o/o of all releves a. of one community typeYY P E a.^ Fig. 19a. Relative frequency cyof the communities g q ties of the Melicytus l ramiflorus ,^— (A, B) and thee Prumno zt y s ferrugineag community ty groupgor (C,D,E) in relation to altitude. P — I 1100

1000-

900-

800-

700-

600-

500-

400-

300-

200-

100-

F1 F2 G1 G2 H1 H2 H3 H4 H5 H6 I1 I2 I3 I4 J1 J2 K1 L1 L2 L3 L4 L5 L6

100% of all releves of one community type

Fig.8 19b. Relative frequency9 cofY the communities of the Ho heria glabratag — (F, G), the Libocedrus bidwillii — (H, I), the Halocarpus^ bi ormis — (J), and the Hebe salici olia communitygroupY g P (K, L) in relation to altitude.

,I Locality / ^ ^. > ^ E. •0 ^ 6. • .d ^ fC Net Granite Hill 54 o o w w p, o Te Kinga ^ ^ a. ^^ >4nP.— Hohonu I ^,, .^ o ,.. ., o^.. o Bonar Range9 ^, n ^o e,..^^ ^ 0K 0 ^ ^ ^►^ Hunt Hill P ^ ^ 0w n (1, ^ a o ,^ r7 ^ ^ ^•^ w Otira ^^,a^ • n o .,. a.a o ^ x ^ ^^ w Karangarua ^ ;.-4D, ^ , al I ^+ fD Q ^^,^o 0 0 ^ ^7. 0 Paringa � o o a I I I ^^ 0 ō ~ ^, ^ 00 ^ o MM o ^ Taramakau rf I ^r► ^G. y y ? ^ 0 (1) ^ M Hari Hari n p,•n CD `C o ^ ^ 0 o ^ Kokatahi o ^ ~ ^. ^w ^. ^.^!• ^ y ~ • 4 Fox y^D~ ^^ ,, a.

iv CampP Creek et ►.. 0 a ri. Al A2 A3 A4 A5 A6 B1 C1 D1 D2 03 D4 D5 D6 D7 D8 E 1 E2 E 3 E4 r.to x , CD 100 % of all releves ^y, of one community type o a Fig.i 20a. . Relative frequency of the communities of th e — ^~ N q Y Melicytusy ramiflorus (A,BB), and the PrumnoP Tt y s ferrugineaS^ communityY groupg 0 N (C, D, E) in relation to the different studyY localities. w Locality

Granite Hill Te Kinga9 Hohonu I I I 1 I I I I I I Bonar Range9 III i i I 1 i Hunt Hill Otira i i 11111 Karangarua I ME I I Paringa

Taramakau

Han Han Kokatahi i iii i UI I I Fox i III I I U I I UI UI Camp Creek

F1 F2 G1 G2 H1 H2 H3 H4 H5 H6 11 I2 I3 14 J1 J2 K1 L1 L2 L3 L4 L5 L6

Fig.S 20b. Relative frequency4 Y of the communities of the H oberia glabrata — (F,p G), the Libocedrus bidwillii — (H, I), the Halocarpus biformisormis — (J), and the Hebe salicifolia communitygroupY g p (K, L) in relation to the different studyY localities.