the woody vegetation of central otago, new zealand

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This article was downloaded by: [UQ Library] On: 09 November 2014, At: 18:10 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK New Zealand Journal of Botany Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzb20 The woody vegetation of Central Otago, New Zealand Susan Walker a , William G. Lee b & Geoffrey M. Rogers c a Landcare Research , Private Bag 1930, Dunedin, New Zealand E- mail: b Landcare Research , Private Bag 1930, Dunedin, New Zealand c Department of Conservation , P.O. Box 5244, Dunedin, New Zealand Published online: 17 Mar 2010. To cite this article: Susan Walker , William G. Lee & Geoffrey M. Rogers (2004) The woody vegetation of Central Otago, New Zealand, New Zealand Journal of Botany, 42:4, 589-612, DOI: 10.1080/0028825X.2004.9512914 To link to this article: http://dx.doi.org/10.1080/0028825X.2004.9512914 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

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Page 1: The woody vegetation of Central Otago, New Zealand

This article was downloaded by: [UQ Library]On: 09 November 2014, At: 18:10Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

New Zealand Journal of BotanyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/tnzb20

The woody vegetation of Central Otago,New ZealandSusan Walker a , William G. Lee b & Geoffrey M. Rogers ca Landcare Research , Private Bag 1930, Dunedin, New Zealand E-mail:b Landcare Research , Private Bag 1930, Dunedin, New Zealandc Department of Conservation , P.O. Box 5244, Dunedin, NewZealandPublished online: 17 Mar 2010.

To cite this article: Susan Walker , William G. Lee & Geoffrey M. Rogers (2004) The woodyvegetation of Central Otago, New Zealand, New Zealand Journal of Botany, 42:4, 589-612, DOI:10.1080/0028825X.2004.9512914

To link to this article: http://dx.doi.org/10.1080/0028825X.2004.9512914

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Page 2: The woody vegetation of Central Otago, New Zealand

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

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New Zealand Journal of Botany, 2004, Vol. 42: 589-6120028-825X/04/4204-0589 © The Royal Society of New Zealand 2004

589

The woody vegetation of Central Otago, New Zealand

SUSAN WALKER

WILLIAM G. LEELandcare ResearchPrivate Bag 1930Dunedin, New ZealandEmail: [email protected]

GEOFFREY M. ROGERSDepartment of ConservationP.O. Box 5244Dunedin, New Zealand

Abstract The present native and exotic woodyvegetation of the rainshadow region of CentralOtago, in eastern South Island, New Zealand, isdescribed. Fourteen present-day associations ofwoody species are related to a gradient in elevationand climate, and to the degree of disturbance by fireand mammalian grazing since human settlement. Afew closed-canopy forest remnants remain only inthe montane zone, while more modified forest rel-icts are scattered across a wider range of environ-ments. Remaining woody plant associations haveoriginated as secondary successions following fire,and range from exotic-species-invaded lowland as-sociations on semi-arid basin floors to prostrate,native-species-dominated associations on mountaintops. Indigenous short-tussock grasslands and seralshrublands are being invaded by exotic trees andshrubs, especially in lowland environments. Dwarfand prostrate low shrub associations on the rangetops may have replaced tussock grasslands since thecommencement of pastoralism, where taller tussock-shrubland communities were destroyed by fires soonafter human settlement. The region's vegetation isnot at equilibrium, and taller, woody communitiestend to develop following removal of fire and

B03034; Online publication date 21 September 2004Received 11 September 2003; accepted 4 February 2004

grazing. Biodiversity restoration goals for deforestedeastern South Island regions such as Central Otagoshould include long-term succession to indigenouswoody communities in representative areas of allland environments.

Keywords vegetation pattern; species-environ-ment relationships; forest remnant; relict; shrubland;woodland; Central Otago; fire and grazing history

INTRODUCTION

In the rainshadow zone to the east of the main axialranges of the South Island, New Zealand, anthropo-genic impact since the arrival of Polynesian peopleabout 750 yr BP has transformed substantial areasof forest and woodland to novel, induced grasslandand shrubland vegetation types (Molloy et al. 1963;Molloy 1969; McGlone 1989, 2001). Lowland en-vironments of eastern South Island inland basins areconsidered particularly high priorities forbiodiversity protection, because they contain distinc-tive habitats and ecosystems that are uncommonelsewhere in New Zealand, and since a very smallpart of their land area (<2%) is currently protectedin public conservation reserves (Overton &Leathwick 2001; Walker et al. 2003).

Most inland eastern South Island environmentswill support woody vegetation, and are likely to re-vert to dominance by woody species in the long termwith conservation management (i.e., the cessation offire and mammalian grazing). Although woody plantspecies have been included in several vegetationstudies (e.g., Mark 1965; Wilson et al. 1989; Par-tridge et al. 1991; Walker et al. 1995), plant ecologi-cal research in inland eastern South Island hashistorically focussed on tussock grasslands (Mark1992 and references therein), alpine vegetation (e.g.,Mark & Bliss 1970; Meurk 1978), and weed inva-sions (e.g., Moore 1954, 1976). In recent years, amore comprehensive knowledge of the plant ecol-ogy and vegetation patterns of inland eastern SouthIsland has begun to emerge through initiatives such

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590 New Zealand Journal of Botany, 2004, Vol. 42

as the Protected Natural Areas Programme (PNAP;Kelly & Park 1986), the tenure review of CrownPastoral Leases (Crown Pastoral Land Act 1998),and research into threatened plants and ecosystems(e.g., Rogers et al. 2000, 2002; Rogers & Walker2002). However, the relict and woody plant commu-nities that occur here today remain among the mostoverlooked and least understood of all New Zealandvegetation types. A more thorough understanding ofthe present-day patterns of relict and seral woodyvegetation is urgently required as a basis forbiodiversity restoration efforts.

In this paper, we describe the present-day woodyvegetation of Central Otago, New Zealand, acrossthe full range of the region's environments. We ex-amine only the woody component of the flora, anddiscuss the environmental gradients and human dis-turbances that account for the distributions of treesand shrubs, and current associations of these woodyplants. To describe the main floristic gradients andtypes of vegetation, we use an extensive database ofgrid-referenced woody species occurrences, com-piled from both existing and new supplementarysurvey plots across the full range of the region'senvironments (Walker et al. 2003). We use recentlydeveloped spatial tools to describe the relationshipsof woody plants with environmental gradients andto summarise the regional environmental pattern(Leathwick & Stephens 1998; Leathwick et al.2003).

METHODS

Study area description and vegetation historyOur study area covers 15 500 km2 (155 grid squaresof 10 x 10 km) of the eastern South Island rain-shadow region of Central Otago (Fig. 1), includingthe major mountain ranges and intermontane basins.A combination of distance from coastal maritimeinfluence and the rainshadow effect created by theSouthern Alps to the west, and the ranges to the southand east, produces an "almost continental" climateon the intermontane valley and basin floors of Cen-tral Otago (Maunder 1965). The lowland climate isextreme relative to other parts of New Zealand: low-elevation sites experience a combination of highsummer temperatures (January mean 17.4°C), lowrainfall, and high evapotranspiration (annual Penmanprecipitation deficit to 887 mm), and among thecoldest winters recorded in New Zealand (annualaverage extreme winter minima in valley floor land

environments as low as -14.2°C), since severe win-ter frosts result from temperature inversions andextended periods of calm conditions. The range topsexperience low temperatures all year round (meanwarmest month temperatures down to 6.1°C), andthe higher mountain ranges carry snow for much ofwinter and early spring (Meurk 1978; Mark &Dickinson 1997). Strong, desiccating föhn winds inspring and autumn and high irradiance due to clearskies are also characteristic climatic features.Semiarid soils occur at low elevations where precipi-tation is less than c. 550 mm, and there are patchesof saline soils on valley and basin floors (Rogers etal. 2000). Pallic soils predominate upslope, and arereplaced by brown soils where the rainfall exceedsc. 800 mm on higher, moister range slopes, withlocal occurrences of acid-leached podzols on gentleslopes (Hewitt 1998). Recent soils occur across arange of environments, mainly on steep unstableslopes and stream alluvium, and Gley soil patchesoccur in local areas of poor drainage.

Some of New Zealand's extant gymnosperm treeswere present in the warm-temperate to subtropicalMiocene flora, which included several Australasianelements (Mildenhall & Pocknall 1984; Pole 1994).However, the present-day flora is largely a productof (i) progressive extinctions of warm-temperatefamilies and genera from south to north from the lateTertiary and early Pleistocene (Mildenhall 1980; Leeet al. 2001), (ii) of radiation, since the late Miocene,of a few non-forest angiosperm families and generain novel habitats provided by mountain building(e.g., Wagstaff & Wardle 1999; Lee et al. 2001), and(iii) of long-distance immigration (Pole 1994). In thelast 2.5 million years, the vegetation physiognomyof the eastern South Island has alternated betweenforest, shrubland, and grassland states in response toglacial cooling cycles. On the basis of the charcoaland pollen records, it appears that natural fires wereinfrequent and local (Ogden et al. 1998; McGlone2001). The dominant herbivores were birds, lizards,and invertebrates, while grazing and browsing mam-mals were absent (Lee 1998). The initialreafforestation of Central Otago following the lastglacial maximum appears to have been slow; coni-fer forests appear to have replaced shrublands andgrasslands after c. 7000 yr BP (McGlone &Wilmshurst 1999), the advance of silver beech(Nothofagus menziesii) onto the range slopes datesto c. 4000 yr BP, and the spread of fusca-typebeeches (e.g., Nothofagus solandri var.cliffortioides) was even more recent (from c. 2000yr BP; McGlone et al. 1996).

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168°E

A

TWTíTyi Jy i ra hnpoiini1

K,i.ir DUNSTAN MT5

go'

oasi»5

O

Fig. 1 Digital elevation map of the study area showing A, the major rivers, towns, and geographical areas mentioned in the text; B, the major mountain rangesmentioned in the text, in relation to the boundaries of the study area; C, the position of the study area in South Island, New Zealand, in relation to population centresand the main divide of the Southern Alps; D, the boundaries of ecological districts (McEwen 1987), and those adjacent to the study area.

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592 New Zealand Journal of Botany, 2004, Vol. 42

Profound vegetation changes occurred with thearrival of humans in the region from c. 750 yr BP,when fires lit by Polynesian hunter-gatherers greatlyreduced the extent of forest and shrubland (Molloyet al. 1963; McGlone 2001; Wardle 2001). Fire-sen-sitive woody species may have been eliminated fromextensive areas of valley and basin floors, hillslopes,dry interfluves, and range tops in the first wave ofhuman occupation. More fire-tolerant species, andthose protected in fire refugia, may have sourcedsecondary successions in areas with longer fire-re-turn times. However, with the commencement ofpastoralism in the last 150 years, frequent fires com-bined with mammalian grazing and browsing furtherrestricted disturbance-sensitive species to inacces-sible steep gorges, rock outcrops, and screes. Stock-ing rates and grazing intensities were particularlyhigh in the first decades of European settlement(O'Connor 1982). Since that time, several exoticwoody species have invaded and spread, and therehas been an increase in seral shrubland comprisinga disturbance-tolerant subset of the indigenouswoody flora. The present vegetation pattern is pri-marily determined by the region's steep elevationgradients, which influence climate (temperature andrainfall) as well as soils (Lister 1965). However, atsmaller scales, local variations in topography andaspect influence soil moisture availability, andstrongly determine vegetation patterns (Wilson et al.1989; Partridge et al. 1991; Walker et al. 1995).

Environmental dataWe drew environmental data from national environ-mental surfaces (Appendix 1). Climate factors in-clude mean annual solar radiation, minimum wintersolar radiation, mean annual temperature, meanminimum temperature of the coldest month, annualsoil water deficit, average monthly ratio of rainfallto potential evaporation, and vapour pressure defi-cit (dryness of the air). Each of these factors wasestimated nationally on a 100-m grid, using thin-plate-spline spatial interpolation of data from irregu-larly distributed New Zealand meteorologicalstations (Leathwick & Stephens 1998). Categoricalsoil variables were derived from the New ZealandLand Resource Inventory (NZLRI; National Waterand Soil Conservation Organisation 1979; Appen-dix 1) and include drainage, age since major resetof soil formation (estimated in three classes, i.e.,younger than 2000 years, 2000 years to postglacial,and preglacial), and classes of total phosphorous,calcium, induration, particle size, and chemical limi-tations to plant growth (e.g., salinity). These data

surfaces were used to obtain estimates of climate andsoil characteristics for each study site.

To summarise environmental variation across ourstudy area, we used a national landscape classifica-tion of land environments (LENZ; Leathwick et al.2003). LENZ groups together sites with similar en-vironmental characters, using an automatic numeri-cal process to classify 15 data layers that describeaspects of climate and landform known to influencethe distributions of biota. There are four differentscales of classification, from Level I (20 Groups) toLevel IV (500 groups). Nineteen of the 100 Level IILand Environments each cover >5 km2 of our studyarea. The geographic information system Arc ViewGIS (Environmental Systems Research Institute2000) was used to calculated the land area and av-erage climate and soil characteristics of each of these19 land environments within the study area, as wellas the percentage of the total national extent of thatland environment contained within Central Otago,and the percentage cover of mapped categories ofpastorally developed land, indigenous forest, andexotic and indigenous scrub in the national LandCover Database (LCDB1 ; Ministry for the Environ-ment 2000).

Floristic dataTo describe the types of woody vegetation that oc-cur in Central Otago, we draw on floristic data froma database of woody species distributions in CentralOtago (Walker et al. 2003), which holds records ofextant native and exotic woody species at grid-ref-erenced locations across the study area (Appendix2). We use 4598 grid-referenced plot records fromtwo database categories:1. Base dataset (presence/absence): this includes

2632 grid-referenced plot records of species pres-ence/absence collated from published and unpub-lished botanical surveys. Most plots havedimensions of 10 x 20 m (exceptions are notedin Appendix 2). We mapped the compiled basedataset to assess the adequacy of its coverage ofthe 19 principal land environments.

2. Supplementary survey dataset (presence/ab-sence): this includes a further 869 plot ( 10 x 20 m)records in forests or shrublands, and 1097 pres-ence/absence observation records of isolatedwoody species added to the database in supple-mentary field surveys carried out in the summersof 1999/2000 and 2000/2001. The supplementarysurveys ensured that the database covers the fullrange of environments, as far as possible, in aspatially representative manner. The average

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Walker et al.—Woody vegetation of Central Otago 593

density of sampling plots across the 19 Level IIland environments in the study area was 0.29 plotsper square kilometre (Table 1).

Species are assigned to six categories on the basisof their frequency in the total database: "very com-mon" >400, "common" 101-400, "less common"41-100, "uncommon" 13-40, "local" 7-12, and"rare" 1-6.

Ordination, classification, and description ofpresent vegetationThe programs Teddybear and Golliwog (Wilson1975) were used for univariate and multivariate sta-tistical analyses of the data, respectively. In ourmultivariate analyses, we omitted records ofregionally local and rare species (59 native, 31 ex-otic) and all plots that contained no species recordsafter these species were omitted, leaving 3389 pres-ence/absence plots containing 125 (107 native, 18exotic) woody plant species.

A Detrended Correspondence Analysis (DCA;Hill & Gauch 1980) ordination was used to arrangethe plots along gradients of vegetation composition.For computational reasons, we also excluded thoseplots that contained a single woody species after thelocal and rare species were omitted, leaving 2901presence/absence plots. To interpret the vegetationgradients, we performed simple regressions of en-vironmental factors (slope, aspect, climate, and soilfactors) and vegetation characteristics (i.e., nativeand exotic richness and percentage exotic species)on plot scores on the two principal ordination axes.We plotted vectors of any significant correlations,together with the ordination scores for individualspecies, on these two ordination axes.

An agglomerative hierarchical classification(cluster analysis, flexible sorting system, Jaccardmeasure of dissimilarity, ß = 0.25; Clifford &Stephenson 1975) was used to identify groups ofplots with similar woody species composition here-after referred to as "woody plant associations" andgroups of ecologically similar species "speciesgroups", on the basis of the presence of the 125woody species in the 3389 plots. The classificationwas arbitrarily terminated at the level of 14 groups(minimum Jaccard dissimilary = 4.59 for plots and1.08 for species), i.e., forming 14 woody plant as-sociations (A to N), and 14 species groups (a to n).We examined the distribution of these woody plantassociations in relation to the land environments, andcompared average climate, soil, and vegetation com-position factors between them using analysis of vari-ance. We plotted the average ordination score of each

woody plant association, and each group of ecologi-cally similar species, on the ordination axes, in or-der to interpret their relationships with the majorvegetation gradients. The number of occurrences ofregionally local and rare species (2 to 12 databaseoccurrences) within each association was tabulated(Appendix 3).

The structural characteristics of the woody plantassociation is described in terms of the presence ofwoody species, since abundance information wasexcluded in order to standardise across our differ-ent data sources. Physiognomic characteristics cantherefore be suggested in the broadest sense only(forest, forest relict, tall shrub, and low shrub asso-ciations) and in accordance with the average heightsof constituent species, rather than the density ofwoody vegetation.

Woody species were categorised according towhether they are indigenous to New Zealand orexotic, and by life-form, as potential canopy species(including trees and several tall shrubs), other tallshrubs (other woody species attaining heights >2 m), lianes, and low shrubs (including small erectshrubs, most whipcord Hebe species, and dwarf orprostrate shrubs).

RESULTS

EnvironmentThe 15 500-km2 study area covers approximately5.8% of New Zealand's total land area, and includes6 Level I Land Environments (20 nationally) and 19Level II Land Environments (out of 100 definednationally) of >5 km2. For each of these Level IILand Environments, we tabulate total land area,number of study plots, percentage of national area,and percentage included within public conservationlands in Central Otago (Table 1). We also tabulatethe percentage area mapped in different land coverdatabase (LCDB1) categories, and their averageenvironmental characteristics within the study area.

Sixty percent of the study area falls within LENZLevel I Land Environment Q (Southeastern HillCountry and Mountains; Leathwick et al. 2003),which covers coastal and interior range slopes andsummits (Table 1). Of these, Central Otago containsa high proportion (c. 69%) of the total national areaof the alpine Land Environment Q3. The study areaalso contains c. 83% of the upland wetland LandEnvironment K5. A further 35% of the study areafalls within Level I Land Environment N (Eastern

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Table 1 Attributes of the 19 major LENZ Level II land environments within the 15 500-km2 Central Otago study area. For each land environment, we show the total area,the number of records in the database, and the percentage of the national area of the land environment contained within the study area. The table also shows the percentagesof each land environment mapped as primarily pastoral, indigenous forest, and indigenous or exotic scrub in the LCDB1, and average environmental characteristics for thestudy area derived from climate surfaces and the NZLRI.

"HGeneral LCDB11 Average environmental characteristics from climate surfaces'' and the NZLRI3

LENZ" Level ILENZ Level II ( and location in Central Otago)

Q

•H

il

S2S a

8.5 w 3

1 %

I•a

•aI

O ^

•a >-•

5 S

S

IE: Dry Central Foothills

E4 (Upper Manuherikia valley floors)

K: Central Upland Recent SoilsK3 (Recent valley gravels)K5 (Manorburn wetlands)

L: Southern LowlandsLI (Southern valley floors)L3 (Waipori wetlands)L4 (Coastal ranges)

N: Eastern South Island PlainsNI (Lakes outwash)N2 (Southern alluvium)N3 (South-eastern toeslopes)N4 (Basin rim hillslopes)N5 (Basin floor terraces)N6 (Recent basin gravels)N7 (Basin floor floodplains)N8 (Clutha basin floors)

P: Central MountainsP5 (Lakes range slopes)

Q: Southeastern Hill Country and MountainsQl (Northern alpine)Q2 (Northern range slopes)Q3 (Rolling range tops)Q4 (Coastal hillslopes)

710 ±95 88(1) 39 2.8 49.7 0.0 2.0 8.8 7.9 -1.8 746 0.41 412 1.7 13.6 -0.61 2.8 3.9 1.2 3.0 1.0 5.0

540±195 124(1) 62 40.0 60.4 0.2 3.9 5.2 9.0 -2.18 744 0.43 481 1.765O±13O 36 (<l) 14 82.8 58.6 0.4 1.3 3.5 7.4 -1.88 666 0.37 343 1.6

290 ±110 220(1)750 ±185 43 (<1)260 ±100 20 (<1)

33 10.7 66.5 0.6 0.6 7.7 9.3 -1.13 641 0.41 389 1.513 3.8 13.7 0.0 0.0 7.9 6.9 -0.79 885 0.33 160 2.35 0.4 68.8 2.5 2.7 10.8 9.5 -0.56 812 0.39 270 2.0

735 0.46 548 1.7600 0.43 468 1.4649 0.39 371 1.5555 0.45 584 1.3510 0.45 609 1.1502 0.45 607 1.1432 0.46 667 0.9430 0.51 773 0.9

340 ± 30170± 120440±165480± 130420 ± 75460 ±100380 ±60240 ± 55

7 (<1)31 (<1)

1822(12)1665(11)1455 (9)122(1)74 (<1)373 (2)

27

40310023803210140

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29.868.988.114.154.499.5

86.683.871.340.893.187.191.184.0

0.0 0.40.0.0.0.0.

0.41.87.00.93.7

0.0 0.80. 1.9

4.53.110.820.66.43.63.28.0

10.310.18.78.89.18.99.110.2

-1.40-0.24-1.19-3.00-2.88-2.86-3.05-3.50

13.9 -0.58 2.313.1 -0.15 1.1

12.9 -0.02 1.612.8 0.02 1.112.8 0.02 2.9

14.0 -0.14 3.013.1 -0.17 2.013.0 -0.01 2.713.6 -0.55 2.113.6 -0.47 2.413.6 -0.43 2.213.5 -0.44 1.113.9 -0.78 2.7

3.3 2.0 2.73.0 2.0 2.1

3.2 2.0 2.61.2 1.1 1.33.0 2.0 1.2

3.0 2.0 2.73.03.9 2.0

3.03.03.23.6

1.9 2.01.9 3.92.2 2.51.9 2.0

.2 4.2

.8 2.2

.0 4.7

.0 1.3

.0 2.9

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3.0 2.0 2.0 2.2 2.33.0 2.1 2.9 1.8 4.5

690±120 39(<1) 3 0.7 0.021.6 18.4 32.1 8.5 -1.52 1370 0.38 168 3.2 13.9 -0.54 2.0 3.0 2.0 3.9 1.0 4.2

1200±265 2843(19) 981 30.5 5.0 1.9 1.1 27.4 5.3 -0.05 1209 0.28 84 3.3 13.4 -0.21 2.0 3.0 1.6 4.0 1.0 4.6700 ±190 2215(14) 976 34.1 31.0 4.1 7.8 28.0 7.9 -1.62 850 0.38 321 2.1 13.5 -0.34 2.0 3.0 1.6 3.9 1.0 4.4970±260 2913(19) 986 68.4 14.6 0.1 1.0 14.8 6.0 -0.61 985 0.30 140 2.7 13.0 -0.09 2.0 3.0 2.0 3.9 1.0 3.7420±140 1227(8) 330 9.3 75.4 0.3 5.3 18.9 8.6 -0.12 803 0.36 237 2.0 12.7 0.12 2.2 3.0 2.0 3.5 1.0 4.0

g

woI' Ministry for the Environment (2000);2 Leathwick & Stephens (1998);3 National Water and Soil Conservation Organisation (1979); 4 Leathwick et al. (2003)

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Walker et al.—Woody vegetation of Central Otago 595

South Island plains) covering glacial outwash andalluvial terraces, fans and floodplains of the basinand valley floors, and range toeslopes. Central Otagocontains high proportions of the national area ofLevel II Land Environments N4, N5, N7, and N8.

Flora and vegetation

Composition and distribution of woody flora andvegetation

A high proportion (36%) of the native woody spe-cies are regionally local or rare (i.e., represented by<13 occurrences in the database; Appendix 3). Thedatabase also contains two nationally endangeredwoody species (de Lange et al. 2004; Category 2:Carmichaelia curta and C. kirkii), two ranked na-tionally vulnerable (Category 3: Hebe cupressoides,Olearia hectorii), one in serious decline (Category4: O.fimbriata), four in gradual decline (Category5: Carmichaelia crassicaule, C. vexillata, Hebepimeleoides var. rupestris, Teucridium parvifolium),five species categorised as sparse (Category 6:Olearia bullata, O. lineata, Pimelea pseudolyallii,Coprosma intertexta, and Hebe propinqua), and twoas range restricted (Category 7: Hebe buchananii,Carmichaelia compacta).

The national land cover database (LCDB1) mapsindigenous forest remnants in land environments ofmid-elevation range slopes, while scrub (both indig-enous and exotic) is mapped in all land environ-ments, but mainly on relatively steep mid-elevationrange-slope and basin-rim toeslope environments(Table 1). Over 40% of the land in the Central Otagostudy area is mapped as primarily pastoral, mainlyin lowland-valley and basin-floor land environments.

Vegetation gradients

Results of the ordination show two principal vegeta-tion gradients (Axes 1 and 2, Eigenvalues 0.79 and0.53, respectively) in the present-day woody vegeta-tion of Central Otago that account for a high propor-tion of the vegetation variation (Fig. 2).

The principal gradient in woody vegetation (rep-resented by ordination Axis 1) is related to climaticcharacteristics along an altitudinal sequence (Fig.2A,B). It reflects the vegetation trend from weedy,low-elevation communities at the left of Axis 1 toprostrate alpine communities at high-elevation sitesat the right of this axis. Rainfall:potentialevapotranspiration ratios and temperatureseasonality increase, while mean annual temperature,annual soil water deficit, and October vapour pres-sure deficit decrease significantly along this gradi-

ent. Percentage exotic woody species and exoticwoody species richness decrease significantly, butnative woody species richness in plots shows nosignificant trend along this axis.

Native and exotic woody species richness andpercentage exotic woody species increase signifi-cantly along the second ordination axis, which is notstrongly related to any of the estimated environmen-tal factors (Fig. 2A,B). Plots with low scores on Axis2 were typically situated in open, fire-prone land-scape positions (e.g., on gently-sloping peneplainsurfaces) that have traditionally been managedfor pastoralism. They tended to support woodyassociations dominated by the characteristicspecies of subalpine "secondary heath" vegetation(Wardle 1991, pp. 205-206), i.e., Carmichaelia,Dracophyllum, Gaultheria, Hebe, Ozothamnus, andPimelea. Conversely, plots with high scores on thesecond major vegetation gradient were situated in therelict stands of closed beech forest that are currentlyrestricted to refugia in gorges and on rock outcrops,cliffs, bluffs, and screes within Central Otago. Sinceforest species are generally intolerant of fire or slowto recover following burning and/or in the presenceof browsing mammals, we interpret the second or-dination axis as a gradient in disturbance by both fireand mammalian herbivory. Thus, we suggest that thesecond axis distinguishes widespread, relatively fire-and grazing-tolerant woody species and vegetationtypes with low Axis 2 scores from more spatiallyrestricted, less modified remnant associations of fire-and/or grazing-intolerant species with high scores.

Classification

The classification defines 14 groups of species withsimilar ecological characteristics, on the basis thatthese tend to occur together in the same vegetationplots (Table 2). Fourteen woody plant associationsare also identified, which group together plots thathave similar woody species composition. The spe-cies and plots of each species group and association,respectively, tend to be clustered together on theprincipal gradients defined by the ordination (Fig.2C,D), and their relationships to climate and fire- andgrazing-disturbance may be interpreted according totheir relative positions along these gradients. Spe-cies groups and associations at intermediate eleva-tions show a wide range of scores on ordination Axis2, whereas those at lowest (<300 m) elevations andthose above 1000 m elevation (i.e., those plant as-sociations with the highest and lowest Axis-1 scores)show less variation. This may reflect the currentabsence of fire- and grazing-sensitive woody species

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and vegetation on the valley floors and at high el-evations, due to the scarcity of refugia and/or thelevel of disturbance there.

Groups of ecologically similar species

Species Group a includes species of closed beechforest stands that are also recorded in forest relictswhere the canopy had been opened or lost (Table 2).A narrow range of scores near the centre of the cli-mate axis reflects their restriction to mid-elevationrange-slope environments, generally in deep gorgesor on cliffs, while high Axis-2 scores indicate theirintolerance of fire (Fig. 2D). Species of EcologicalGroup b have a slightly wider environmental rangethan those of Group a, but they are nevertheless alsorestricted to fire-protected sites. They are seldomassociated with beech forest fragments, and may bederived from forest or woodland types that no longeroccur in Central Otago, which may have includedthese species.

Species in ecological groups c, d, e, andfoccurprincipally on the semiarid continental valley andbasin floors, and include numerous woody weedspecies (Table 2). Two native shrubs (Hebepimeleoides var. rupestris and Pimelea aridula) areclassified within Species Group d, and four nativetrees occur in Species Group e (Olearia lineata,Cordyline australis, Sophora microphylla, andKunzea ericoides). The shrubs Muehlenbeckiaaustralis, Helichrysum lanceolatum, and Coprosmacrassifolia in Group e have somewhat higher Axis1 and 2 scores, indicating lower tolerance of fire and/or drought. Leptospermum scoparium (also in spe-cies group e) is positioned towards the mesic centreof Axis 1 and lower on Axis 2, which we interpretto indicate a relatively wide ecological tolerance andsome capacity to recover after fire (Fig. 2D). Shrubsand lianes in Ecological Group f(e.g., Parsonsiacapsularis, Scandia geniculata, Clematis marata,Aristotelia fruticosa, Corokia cotoneaster, Hebesalicifolia, H. subalpina, and Coprosma rugosa)tend to have higher Axis 1 and 2 scores that thoseof groups c to e, suggesting that they are somewhatless tolerant of fire and extremes of drought, frost,and grazing. A few have relatively low Axis-2 scores(e.g., Olearia bullata, Coprosma rugosa, and the rareliane Carmichaelia kirkii) and survive mainly inmoist, steep, or otherwise sheltered fire refugia. Incontrast, the shrubs and lianes in Group g typicallyhave low Axis-2 scores and are widespread intopographically open country.

Tall and low shrubs of ecological groups h, i, and/ have moderately high scores on the climate

gradient, but have low Axis-2 scores, and are asso-ciated with fire-prone tussock grasslands of the up-per montane and subalpine zones (Fig. 2D; Table 2).Several species in the genera Coprosma, Gaultheria,Pimelea, and Carmichaelia are classified withinthese groups, together with Hebe epacridea,Muehlenbeckia axillaris, and Helichrysumintermedium var. selago. The higher-elevation spe-cies groupsj and k include low-alpine shrubs includ-ing Brachyglottis revoluta, Dracophyllum uniflorum,Hebe odora, Olearia nummularifolia, Ozothamnusleptophyllus, Phyllocladus alpinus, and Podocarpusnivalis. Moderately high Axis-2 scores suggest thatthey are absent from areas with more intensive burn-ing and grazing histories (Fig. 2D). The two groupsof tall and low shrubs that occur at the highest el-evations are categorised as widespread species withlower Axis-2 scores (Species Group m), and thosewith more localised distributions (Species Group n).Group m includes Dracophyllum muscoides, D.pronum, Hebe buchananii, H. hectorii var. hectorii,H. lycopodioides var. lycopodioides, H.pauciramosa, and H. pinguifolia. The apparentlymore fire-sensitive group n includes Halocarpusbidwillii, Cyathodes pumila, Dracophyllum politum,Hebe imbricata var.poppelwellii, and H. propinqua.

To better understand the distribution of life-formgroups among the high-elevation woody speciesrecorded in Central Otago (i.e., 48 species in groupsh to n), we compared average Axis 1 and 2 ordina-tion scores between 14 tall shrubs, 4 whipcord Hebespecies (H. hectorii var. hectorii, H. imbricata var.poppelwellii, H. lycopodioides var. lycopodioides,and H. propinqua) and 30 other low shrubs usingTukey's test. The 30 low shrubs have higher Axis-1 and lower Axis-2 scores (both P < 0.05 by Tukey' stest) and, therefore, on average, extend to higherelevations, and occur in more fire- and grazing-pronesites than tall shrubs in Central Otago. The fourwhipcord Hebe species extend to higher elevationsthan other low shrubs (they have higher averageAxis-1 scores), but may be less tolerant of fire and/or mammalian herbivory since Axis-2 scores are alsohigher (both P < 0.05 by Tukey's test).

Woody plant associations

Two of the 14 woody plant associations (A to N;Tables 2 and 3) are categorised as forests and forestrelicts (associations A and B, respectively). The re-mainder are categorised by elevation zone; i.e., aslowland and lower montane associations (C and D),montane and subalpine associations (E, F, and G),and high-elevation associations (H to N).

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A

CLIMATE GRADIENT

continental valley floorswith hot, arid summers

and frosty winters

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Rainfall:potentialevapotranspiration

ratio

CMM'5

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Axisi2 3 4 5 7 8 9

*

íAxisi

Fig. 2 Results of the ordination of present woody vegetation. A, Major gradients in woody vegetation (climate: Axis 1, and fire: Axis 2); B, significantcorrelations with the gradients (direction and percentage of variation explained by environmental and vegetation factors); C, mean positions (and stand-ard deviations) of present-day woody plant associations (A to N); D, groups of woody plant species on these gradients.

go'

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598 New Zealand Journal of Botany, 2004, Vol. 42

Table 2 Two-way table of the classification of present-day woody vegetation in Central Otago, showing thepercentage presence of woody species, in species groups (Gp) a to n within sample plots of woody plant associations Ato N. *, exotic species. Four categories are recognised: 1, montane forests and forest relicts; 2, associations ofintermontane basin floors and range toeslopes; 3, associations of montane and subalpine range slopes; and 4,associations of upper slopes and range tops.

Gp Species

a Raukaua simplexHoheria glabrataCoprosma cuneataNothofagus solandri

var. cliffortioidesCoprosma "taylorae"Podocarpus halliiGriselinia littoralisPseudopanax colensoiNothofagus menziesiiMyrsine divaricataCoprosma rhamnoidesCoprosma colensoiPseudopanax crassifoliusRubus cissoidesCarpodetus serratusNothofagus fusca

b Olearia cymbifoliaOlearia avicenniifoliaCoprosma linariifoliaHoheria lyalliiCoprosma rigidaMelicope simplexOlearia arborescensCoprosma pseudocuneataPittosporum tenuifoliumFuchsia excorticata

c *Rubus fruticosus*Clematis vitalba*Malus domestica

d Pimelea aridula*Populus alba*Lupinus arboreus*Thymus vulgaris

1

A

325

11

61564760589344677247444977

4

21157

Hebe pimeleoides var. rupestrise *Cytisus scoparius

Kunzea ericoides*Pinus spp.*SalixfragilisCordyline australisLeptospermum scoparium*Ulex europaeusSophora microphyllaCoprosma virescens*Sambucus nigra*Crataegus monogynaMuehlenbeckia australisHelichrysum lanceolatumCoprosma crassifoliaOlearia lineata

22

2

B

333

22313157

1172247626234428333

3

31

<1118

<1323

7553

2

C

1

1

<1

1<1

1<1

21223641

436

251823

3231

16156

2

D

1

1

124

2924

14

21

374311

3

E

1511

<11

<1<1

3<1

<11

<11

<11

<1

<1<1<1

117

<1161

10115522662

217

1233

13

Woody vegetation category3

F

2

41

831231

213

4

21

1

G

<111

<1<1

2

<1

<1

<1

<1

2<1<1

194414

35

<1

2121

<11

H

<1<1

<11

<1

<1<1

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1

1

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1

1

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2

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4

K

3

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<1

3

<11

7

L

2

2

M N

<1

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Walker et al.—Woody vegetation of Central Otago 599

Table 2 (Continued)

Gp

/

/

g

h

ii

k

Species

*Ribes uva-crispaClematis marataHebe subalpinaHebe salicifoliaAristoteliafruticosaOlearia bullataParsonsia capsularisCorokia cotoneasterCoprosma rugosaCoprosma intertexta*Sorbus aucuparia*Populus nigra*Pseudostuga menziesii*Sorbaria tomentosaCarmichaelia kirkiiScandia geniculataDiscaria toumatou*Rosa rubiginosaMuehlenbeckia complexaRubus schmidelioidesCoprosma propinquaMelicytus alpinusCarmichaelia petrieiOlearia odorataMuehlenbeckia axillarisPimelea sericeovillosaHelichrysum intermedium

var. selagoPimelea prostrataCarmichaelia crassicauleCarmichaelia vexillataPimelea traversiiCoprosma atropurpureaGaultheria parvulaHebe epacrideaPimelea poppelwelliiCarmichaelia compactaCoprosma depressaCoprosma rubraPimelea pseudolyalliiDracophyllum uniflorumPodocarpus nivalisBrachyglottis revolutaMyrsine nummulariaGaultheria crassaDracophyllum longifoliumCoprosma ciliataGaultheria depressa

var. novae zelandiaeHebe rakaiensisOzothamnus leptophyllusCoprosma cheesemaniiGaultheria macrostigma

A

4

25

412

4

2

1

B

295

1510142

26102

<1

<11

2411471241521717437

<1832

<111

143

1820

620202832

3

1922138

2

C

51

419

12212

<1

<1

3532114

1069662

1

<11

1

1<1

1

11

12

<11

D

22

5

1

1

136024

141422211

3

1

1

E

118268

111

10271111

<11

8772564272483745

2<1

2

<1<1<1

2

<1

1

<1111

<11

<17

15

<1

Woody vegetation3

F

21

3

1111

1

6650129

1387231921

823

1

1

11

11

G

23332

29

4421

<1

<1

681627

62313444311

<11315

1

432

12

<14

2433

H

<1

<1

445

126

213

<1295

<11

<1

<13

<11

<1

<1

category

I

11

3

<1<1

<1

211

3122

11

<1

1353

4

2

1<1

813<1

964211

23141

J

14

1

1

2

151

227

4

23

2

76726

1542

34

51

316113

4

K

<13

1

<11

<1

3

9

11

<1<1

1

<11

121

2

810

1163511

<1202456

L

11

54

10096

724

M

<1

14

<1

<1

<1

<1

<1

1

1

1

N

1

2

1

2

2

2

1

1

1

(Continued over page)

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600 New Zealand Journal of Botany, 2004, Vol. 42

Table 2 (Continued)

Gp Species

Hebe odoraPentachondra pumilaLeucopogon colensoiPhyllocladus alpinusGaultheria antipodaOlearia nummularifolia

I Coprosma petrieiPimelea oreophilaGaultheria depressavar. depressa

Gaultheria nubicolam Dracophyllum muscoides

Hebe pauciramosaHebe buchananiiHebe hectorii var. hectoriiHebe pinguifoliaDracophyllum pronumHebe lycopodioides.

var. lycopodioides

1

A

2

25

21

2

n Hebe imbricata var. poppelwelliiHebe propinquaCyathodes pumilaHalocarpus bidwilliiCoprosma perpusillaDracophyllum politum

B

2010198

2383

2122

2128

<113

<1

231

2

C D

<121

1 1

1

1

<1

E

1<1

1

<151

<1

<11

<1<1

Woody vegetation3

F

2

1

2168

2

1

1

G

<1

27

416

1510

1

<1<1

<1

1

H

<1<1

<15

8131

219

5<1

10<1

1<1

category

I

14187

223582

410231

<1141

113

1

J

1522

5

26

3325

3122352

263

21314

4

K

38327

15585

2322

721

72

<1

141

2697

255

L

2

99

41

926

226

6

5

M

2

<1

26

25

195<1197

<1157

2

N

1

501814

5125

24

25

2

1

4

Beech forest remnants (Association A: 2% ofplots) are closed-canopy stands that have escapedfire since human settlement in parts of the Umbrellaand Nokomai ecological districts (Fig. 1; McEwen1987) in the south-west (including the eastern slopesof Mt Benger in the Clutha Valley), in the Lindis,Pisa, and Wanaka ecological districts in the north-west, and in gullies in Waipori ecological district inthe south. Their canopies comprise Nothofagusmenziesii (silver beech), or mixtures of N. menziesii,N. solandri var. cliffortioides (mountain beech), andN. fusca (red beech), occasionally with Elaeocarpushookerianus (Table 2; Appendix 3). Remnants of N.solandri var. cliffortioides forest in the Lindis Val-ley (described by Wardle 2001) could not be sam-pled in this study, but would probably have beenincluded in this association, which has a high aver-age score on the fire-intolerance gradient (Fig. 2C).Species of ecological groups a and b predominatein these forest remnants, although Cytisus scopar-ius, Kunzea ericoides, Muehlenbeckia australis, and

Hebe salicifolia are occasionally recorded on forestedges.

Widespread forest relicts (Association B: 7% ofplots) are variable, relatively native-species-richwoody relicts that are scattered in several subalpineand montane land environments, and occasionally onthe basin rim toeslopes (Table 3). They contain fewwoody weed species, but elements of former forestcommunities in species groups a or b are invariablypresent (Table 2). Examples that have been leastmodified by fire and grazing tend to include shrubspecies in Groupf, while more modified examplescontain Group-g species. A number of regionallyrare forest species are occasionally present (Appen-dix 3). Some forest relict associations at the highestelevations harbour relatively fire sensitive speciesfrom groupsj and k (e.g., Dracophyllum longifolium,Phyllocladus alpinus) that may have been compo-nents of more continuous upland tall-shrubland orlow-forest canopies prior to modification by frequenthuman fire.

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Table 3 Environmental attributes of the 14 present-day woody plant associations (A to N) in four categories (1 to 4 as for Table 2). Land environments (LENZ)containing >10% of the sampling plots classified in each association are listed. 81

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3

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2

3

4

A

B

C

D

E

F

G

H

I

J

K

L

M

N

Present-daywoody plant association(mean elevation + SD)

Beech forest remnants(500+ 160 m)Widespread forest relicts(860 + 240 m)Broom-gorse association(460 + 230 m)Briar association(420 +210 m)Matagouri-mingimingi

association (570 + 210 m)Dry Melicytus association(680 +260 m)Matagouri-native broom

association (700 + 230 m)Highly modified subalpineassociation (1170 ±310 m)

Ozothamnus association(1180 + 250 m)Dracophyllum association(1120 +200 m)Hebe odora-mountain toatoa

association (1030 + 280 m)Brachyglottis revoluta

association (1340 + 130 m)Prostrate Dracophyllum

association (1520 + 160 m)Widespread alpine association(1300 +270 m)

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6.76

8.85

9.29

8.43

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7.67

5.38

5.22

5.61

5.72

4.21

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LENZ (% plots)

Q2 (62), Ql (12)

Ql (39), Q2 (28) Q3(16), Q4 (12)N3 (21), N5(15),N4(14),Q4(13),Q2(10)N4 (53), N8 (16)

N4 (33), Q2 (33),N3 (12)Q2 (43), N4 (37)

Q2(35), Q4(15),N3(14), Ql (11)Ql (47), Q3 (34),Q2(13)Ql (58), Q3 (35)

Ql (81), Q3 (13)

Q3 (68), Ql (14)

Ql (78), Q3 (22)

Q3 (56), Ql (43)Q3 (56), Ql (33)

retalW

oody vegetation

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The broom-gorse association (C: 10% of plots)is widespread in the lowland and lower-montaneland environments of Central Otago that are char-acterised by a high degree of pastoral development(Fig. 2C; Table 1). It is common along the length ofthe Clutha Valley, in the eastern Waipori and north-ern Macraes ecological districts, and in the higher-altitude, north-eastern parts of Maniototo EcologicalDistrict. It is also recorded on mine-tailings and regu-larly disturbed sites in the low-alpine land environ-ments Q1 and Q3, and is therefore capable ofextending to higher elevations. The association typi-cally forms dense, exotic-species-dominatedshrublands. Cytisus scoparius (broom) and/or Ulexeuropaeus (gorse) form the canopy in most plots,while Rosa rubiginosa and Discaria toumatou arecommon components, and Lupinus arboreus andRibes uva-crispa are present infrequently. Pinusspp., Salixfragilis, Crataegus monogyna, Sambucusnigra, and Populus alba are occasional emergents.Several regionally uncommon exotic species wererecorded in Association C (Appendix 3), but, apartfrom Discaria toumatou, native woody species arerelatively rare.

The briar association (D: 5% of plots) is charac-teristic of the less pastorally developed lowerhillslopes of the Upper Clutha, Lindis, andManuherikia valleys that experience Central Otago'smost extreme continental climates and high annualsolar radiation (Table 1). The association is typicallyspecies poor (c. 2-3 species), and may be sparse,with shrubs (1-4 m) of Rosa rubiginosa (sweet briar)as the principal woody species. Thymus vulgarisoccurs in approx. 30% of plots and may form a con-tinuous low subcanopy, while Kunzea ericoides,Melicytus alpinus, and Coprosma propinqua arecommon secondary components. Relict trees of So-phora microphylla are occasionally present. Oleariabullata and O. lineata are often recorded in the briarassociation in the southern half of the study area(e.g., in the Macraes, Rock and Pillar, Waipori, andUmbrella ecological districts).

The matagouri-mingimingi association (E: 25%of plots) is the most widespread woody plant asso-ciation in Central Otago, although it is rarely foundin the low-alpine zone, on the Maniototo Basin floor,and in southern land environments experiencing lowmean annual solar radiation inputs, and/or wherehigh rainfall:potential evapotranspiration ratios re-sult from the coastal influence (Table 1). It formsdense to sparse shrublands (often referred to as "greyscrub") from 1 to 4 m tall, and invariably includesthe common, disturbance-tolerant species of Species

Group g, although members of groups d, e, andfarealso frequent components (Table 2). Native forestspecies in species groups a and b were very occa-sionally recorded, including some that are regionallyuncommon (Appendix 3). Exotic species such asSambucus nigra, Crataegus monogyna, Cytisus sco-parius, Ribes uva-crispa, Thymus vulgaris, and Ulexeuropaeus are often present, and occasionally domi-nate the association, and several regionally uncom-mon woody weeds were recorded occasionally(Appendix 3).

The dry Melicytus association (F: 4% of plots)occurs principally on steep slopes in the montane andsubalpine zone in the Kawarau and Cromwellgorges, and occasionally extends into the low-alpinezone. Average elevation and mean annual solar ra-diation are slightly higher, and mean annual tempera-ture is marginally lower than at sites occupied by thematagouri-mingimingi association (E, above; Table1), although annual soil moisture deficits and Octo-ber vapour pressure deficits are similar. Scatteredlow shrubs of Melicytus alpinus are almost invari-ably present; two-thirds of plots contain Discariatoumatou, and approximately half contain the lowshrub Pimelea aridula or the exotic Rosa rubiginosa.Carmichaelia petriei, Olearia odorata, Coprosmapropinqua, and Pimelea oreophila are common as-sociated species, as are Thymus vulgaris and wildingpines (Pinus spp.).

The matagouri-native broom association (G: 7%of plots) occupies higher, cooler, and more mesicenvironments than those supporting briar,matagouri-mingimingi, and dry Melicytus associa-tions (D, E, and F; Table 1). It typically comprisesscattered shrubs of Discaria toumatou andCarmichaelia petriei, and occasionally Oleariabullata (Species Groupf), Carmichaelia crassicaule(Species Group h), and the low shrubs Pimeleaoreophila and Gaultheria depressa var. depressa(Species Group l; Table 2). Coprosma propinqua,Muehlenbeckia complexa, Melicytus alpinus, andRosa rubiginosa (Species Group g) also occur here,but are less conspicuous than at lower elevations.

The highly modified subalpine association (H: 7%of plots) is recorded in a wide altitudinal zone ofsparse, fire-prone upland tussock grasslands, mainlyin Central Otago's northern ecological districts, butalso locally on the crests of Rough Ridge and theRock and Pillar Range. The woody vegetation isdominated by a few relatively fire tolerant low shrubspecies, of which Pimelea oreophila and Gaultheriadepressa var. depressa (Species Group l) are theprincipal species (Table 2).

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The Ozothamnus alpine association (I: 8% ofplots) is present in the zone above the regionaltreeline on all of the main Central Otago mountainranges. Numerous dwarf and prostrate shrubs arepresent, of which Gaultheria depressa var. depressaand Pimelea oreophila (Species Group l) are themost common (Table 2). Other common woodyspecies include the low shrub Melicytus alpinus(Species Group g) and taller species such asOzothamnus leptophyllus and Hebe odora (SpeciesGroup k) and Dracophyllum uniflorum (SpeciesGroup j). Brachyglottis revoluta (Species Group j)occurs in the Umbrella, Nokomai, and Old ManEcological Districts.

The Dracophyllum alpine association (J: 4% ofplots) occurs mainly on steep slopes in the southernand eastern mountain ranges of the Dansey, Um-brella, and Nokomai ecological districts, and therolling uplands of the Manorburn, Waipori, andRock and Pillar ecological districts, which receivelow annual solar radiation inputs and annual waterdeficits, and less-seasonal temperature regimes, thanthose further north (Table 1). Dracophyllumuniflorum and the low shrubs Gaultheria depressavar. novae-zelandiae and G. crassa (Species Groupj) are the principal species (Table 2). Although lowshrubs predominate, several taller shrubs also occurhere, including Brachyglottis revoluta (SpeciesGroup j) and Ozothamnus leptophyllus and Hebeodora (Species Group k).

The Hebe odora-mountain toatoa association (K:9% of plots) is most widespread on gently sloping,uplifted peneplain surfaces in the south of the region,particularly on the Rock and Pillar and Lammerlawranges, although examples are recorded on theHawkdun and St Bathans ranges and on the KakanuiMountains in the east, and in the Old Man, Umbrella,and Nokomai ecological districts in the south. Hebeodora (Species Group k) is the characteristic domi-nant shrub and can form dense stands, but the rarerH.propinqua (Species Group n) and H.pauciramosa(Species Group m) are also recorded (Table 2). Oc-casional remnants ofPhyllocladus alpinus (SpeciesGroup k) and Halocarpus bidwillii (Species Groupn), and more frequent occurrences of Ozothamnusleptophyllus, Olearia nummularifolia (SpeciesGroup k), and Leptospermum scoparium (SpeciesGroup e) within this association suggest that taller,longer-lived shrubs were more widespread in theseenvironments prior to the onset of higher fire fre-quencies.

The Brachyglottis revoluta alpine association (L:2% of plots) is characterised by the geographically

restricted erect shrub B. revoluta, on moderatelysteep slopes in the ranges of the Umbrella, Nokomai,and Old Man ecological districts. Dracophyllumuniflorum and Gaultheria depressa var. depressa arethe most frequent subsidiary woody species, whileHebe rakaiensis, H. hectorii var. hectorii, Melicytusalpinus, and the low shrubs Coprosma petriei,Dracophyllum muscoides, D. pronum, Gaultherianubicola, G. crassa, Myrsine nummularia, andPimelea oreophila are relatively common (Table 2).

The prostrate Dracophyllum alpine association(M: 6% of plots) occurs on range tops throughoutCentral Otago. It is most extensive on the GarvieMountains and the Old Man and Pisa ranges, butoccurs locally on the Dunstan Mountains, the Rockand Pillar Range, and on Rough Ridge. Prostrate lowshrubs of Dracophyllum muscoides dominate overlarge areas of range summits, with Gaultheriadepressa var. depressa, Dracophyllum pronum,Melicytus alpinus, Hebe buchananii, H. hectorii, H.lycopodioides var. lycopodioides, and Pimeleaoreophila as subsidiary woody species (Table 2).

The widespread alpine association (N: 5% ofplots) was recorded in the Old Man, Pisa, andDunstan ecological districts, and is also scattered inthe Manorburn and Waipori ecological districts, in-cluding within the wetland land environments K5and L3. Dwarf and prostrate shrubs predominate,including Gaultheria nubicola, Coprosma petriei, C.perpusilla, Dracophyllum pronum, D. muscoides, G.depressa var. depressa, and Pimelea oreophila (Ta-ble 2).

DISCUSSION

Effects of climate and disturbance on thevegetation patternThe present pattern of woody vegetation of CentralOtago is determined not only by the environment ofthe region but also by the evolutionary and recenthistory of the region and the response of the nativeflora to disturbance following the recent arrival ofhumans. Climate determines the principal regionaltrend in woody vegetation, from exotic-species-in-vaded lowland associations on the valley floors (inparticular broom-gorse and briar associations) to theprostrate Dracophyllum alpine association on therange tops. We interpret a secondary trend in thewoody vegetation as reflecting the degree of distur-bance that has occurred since human settlement,initially and primarily by fire and later by mamma-

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lian grazing and browsing. As a consequence ofevolution in a wet, maritime climate with infrequentnatural fire (estimated return times in the Holoceneperiod 1000-2000 yr; Ogden et al. 1998) the NewZealand woody flora generally lacks fire adaptations(Lee 1998; McGlone 2001); many tree and shrubspecies are killed by fire, and woody vegetation typi-cally requires long periods to recover in its wake.Moreover, since mammals were absent throughoutmuch of their evolution, most woody species haveevolved few defences against mammalian herbivoryand grow and reproduce poorly under even moder-ate grazing regimes (Lee 1998). Fires significantlyreduced the area of woody vegetation in CentralOtago from c. 750 BP (McGlone 2001), and theexceptionally high stocking rates and rabbit"plagues" of the first decades of European settle-ment (O'Connor 1982) would have reduced any re-maining palatable woody species to scarcity or localextinction. Consequently, only the most disturbance-tolerant indigenous woody species persist at both lowand high elevations today. Between the valley floorsand the former treeline, woody plant associationsrange from a few forest stands and scattered, modi-fied forest relicts in refugia where dissectedmicrotopography, shady aspects, and/or steep slopesprovide shelter (associations A and B), to more wide-spread, secondary montane associations (associa-tions E, F, and G: Matagouri-mingimingi, DryMelicytus, and Matagouri-native broom associa-tions, respectively).

Intermontane basin floors and range toeslopes

Although described as "almost continental" byMaunder (1965), Central Otago's lowland climateis not severe when compared with continental areasworldwide. Hubbard & Wilson (1988) calculated theindex of Thornthwaite (1948) and the de MartonneAridity Index (Meigs 1953) and concluded that thevalley floors were semiarid by these criteria. Theynoted that although many authors had previouslyapplied the terms "desert" or "semi-desert" to thevegetation, this was a state "induced by human dis-turbance, burning and especially by grazing" ratherthan climatic conditions. Although Wardle (1991,pp. 244-245) suggested that Central Otago's basinfloors previously contained significant areas of natu-ral temperate grassland, native shrubs occur todayin the most severely drought and frost-prone envi-ronments on valley floors. This suggests that theregimes of frost and drought experienced here areinsufficient to have excluded tall shrubland or lowforest in pre-settlement times (Walker et al. 2004).

The suitability of Central Otago's basin floor envi-ronments for native woody species is also indicatedby the widespread occurrence of exotic shrubs in thelowlands, including the most frost- and drought-prone areas. These exotic shrubs may be betteradapted to fire and grazing than New Zealand na-tive species, but are not particularly tolerant of ex-treme droughts and frosts. For example, Ellenberg(1988) classified Cytisus scoparius, Crataegusmonogyna, Ribes uva-crispa, and Rosa rubiginosaas Category 2 "oceanic" and Salixfragilis and Sam-bucus nigra as Category 3 "between oceanic andsuboceanic" on his nine-point scale of continentality.

Due to post-settlement fire and browsing, nativewoody species are unlikely to extend to their poten-tial environmental limits in Central Otago's mostextreme lowland environments today. Those nativewoody species that remain relatively common in theCentral Otago lowlands today (principally SpeciesGroup g) are probably a small subset of a formerlymore species-rich lowland woody flora that wascapable of withstanding some grazing and periodicfires as well as local extremes of drought and frost.A reduction in fire frequencies and grazingintensities may be contributing to a local expansionin some of these species (particularly Coprosmapropinqua and Discaria toumatou) in some parts ofthe region, while in other areas their range may becontinuing to contract due to continued or intensi-fied pasture development. However, more palatableand fire-sensitive indigenous species (e.g.,Carmichaelia kirkii, Hebe pimeleoides var.rupestris, Scandia geniculata) are now almost en-tirely restricted to dense secondary shrublands or tobluffs and rock tors that provide the greatest protec-tion from fire and/or grazing. It seems likely thattheir ranges have been truncated by fire, grazing,and/or the removal of the matrix of taller woodyvegetation since the arrival of humans. Theirpopulations may be expected to contract furtherwhere present disturbance regimes continue. Theexotic component of valley-floor woody plant asso-ciations derives from the invasion of novel speciesfrom domestic introduction points in the lowlands,and it seems likely that these will extend their rangesin the region in the future.

The briar association defined in our classificationincludes the most north-facing, low-elevation com-munities of the Kawarau Gorge described by Par-tridge et al. (1991), as well as certain lowlandcommunities described by Hubbard & Wilson (1988;Community D) and by Walker et al. (1995; e.g.,Communities B to H).

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Montane and subalpine range slopes

The subfossil evidence suggests that forests ofPodocarpus hallii and Phyllocladus alpinus weremore widespread in Central Otago than those ofbeech (Nothofagus) species prior to human settle-ment. However, the only closed-canopy remnants ofmontane forest that remain in Central Otago todayare dominated by beech species. This suggests thatgymnosperm-dominated forests were more easilydestroyed by fire than beech forests, perhaps becausethey tended to occupy more fire-prone dry interfluvesites, or because they were more flammable due tostructure characteristics and/or higher concentrationsof volatile oils in the foliage and wood. Today,Podocarpus hallii, Phyllocladus alpinus, andHalocarpus bidwillii are constituents of more modi-fied forest relicts that vary from single shrubs toassemblages of several woody species, and are scat-tered across a much wider range of land environ-ments in Central Otago.

The remaining woody plant associations of mid-elevation range slopes (E to G) are widely distrib-uted across land environments between the valleyfloors and the former treeline that offer little protec-tion from fire and grazing. These are secondarywoody associations that range from scattered shrubswithin short- and tall-tussock grasslands, to densestands that cover several square kilometres. Theycomprise native tall and low shrubs in species groupsg, h, and i that are seldom recorded within CentralOtago's beech forest remnants (exceptions areCoprosma propinqua and Gaultheria depressa) al-though they do occur in more modified forest rel-icts. It appears that these species groups are arelatively light-demanding subset of the prehumanwoody flora that have expanded their distributionsfrom more localised, seral habitats following theremoval of taller woody cover by fire.

Many of the plant communities described in theKawarau Gorge (Partridge et al. 1991) and UpperClutha Basin (Wilson et al. 1989) on the basis of thewhole vascular flora are included in the secondarymontane woody plant associations E to G. Partridgeet al. (1991) described most of the vegetation of theKawarau Gorge as "physiognomically…. sweetbriar(Rosa rubiginosa) and matagouri (Discariatoumatou) open shrubland" and these are probablyequivalent to our matagouri-mingimingi and dryMelicytus associations. The matagouri-native broomassociation (G) may occur as dense stands in shel-tered gullies and gorges at moderate to high eleva-tions, but their woody plants are often widely spaced,and these are probably more usually described as

minor components of present-day tall-tussockgrasslands (e.g., Mark 1992).

Upper slopes and range tops

Our results show a high regional variability in woodyspecies composition above the pre-settlementtreeline in Central Otago, which is defined by the11°C mean warmest month temperature isotherm(hereafter MWMT; Wardle 1991), that lies at anaverage elevation of 1180 m a.s.l. across the studyarea. However, a general trend is recorded fromdense stands or scattered individuals oftall and erectlow shrubs (often within tall-tussock grasslands invarying degrees of canopy openness) to associationsof dwarf and prostrate low shrubs on or near the ridgecrests. Woody species and associations (H to N) withpredominantly high-elevation distributions show asmall range of values on the fire- and grazing-intol-erance gradient, indicating that, as in the lowlands,a suite of disturbance-sensitive species may havebeen selectively removed since human settlement.

Although alpine environments in Central Otagohave not experienced the same degree of pastoraldevelopment as the lowland and montane zones, theyare characterised by gently rolling topography andan absence of fire-refugia. Moreover, vegetationrecovery from fire is constrained by low plant pro-ductivity under alpine climatic conditions (e.g., Bliss& Mark 1974). Pollen evidence from upland peatmires (e.g., McGlone et al. 1997) and analysis ofpresent-day limits of tall shrubs in relation to climaticzones (Walker et al. 2004) suggest that tallshrublands including species such as Phyllocladusalpinus and Halocarpus bidwillii grew almost to thesummits of the Central Otago's schist ranges at thetime of human arrival, and that most of land envi-ronments Q1 and Q3 in Central Otago lie below theupper climatic limit of the low alpine zone. On thisbasis, McGlone (2001) concluded that a "complexpenalpine shrubland-grassland" occupied alpine ar-eas of Central Otago prior to human settlement, andMcGlone et al. (1997) suggested that "alpine uplandswere also affected by the destruction of shrubland"at the time of human settlement. Today, tall shrubssurvive in the alpine zone chiefly where rock tors orpermanent moisture provide protection from fire, andtheir positions on the fire- and grazing-intolerancegradient identified by the ordination suggest that theyare, on average, more sensitive to fire and grazingthan low shrubs. These patterns also suggest that tallshrubs may have been selectively removed from tallshrublands and tussock-shrublands across much ofthe alpine zone by the fires that followed first human

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settlement, leaving fire-resistant tall tussock grassesas the dominant life forms (mainly Chionochloarigida and C. macra, but also C. rubra on lowerpeneplain surfaces).

Common low shrubs in the genera Coprosma,Dracophyllum, Gaultheria, and Pimelea (speciesgroups l and m) are recorded across all of the sevenupland woody plant associations recognised in ourclassification of woody vegetation. These low shrubsoccur as infrequent to codominant elements in up-land tussock grassland vegetation, and form the pre-dominant plant cover at the highest elevations. Theprostrate Dracophyllum alpine association (ourwoody plant association M) is probably analogousto "high alpine cushion-field" vegetation (Mark &Bliss 1970; Bliss & Mark 1974; Mark & Dickinson1997). Since low shrubs appear less susceptible tofire and grazing than tall shrubs, they may haveexpanded their ranges and dominance since humansettlement, especially in the early pastoral era, whentall tussocks were removed from large areas of therange summits and upper slopes by a combinationof frequent fire and mammalian grazing. It followsthat the prostrate low shrub communities whichdominate extensive areas of Central Otago's alpinezone today may be almost wholly an artefact ofhuman disturbance rather than an evolutionary re-sponse to the high alpine environment. We suggestthat the constituent low shrub species of today'salpine low shrub associations were locally present,but far more restricted, prior to human settlement.

CONCLUSIONS

Although limited to woody plant life-forms and pres-ence-absence data, our study comprises the firstquantitative assessment of patterns of vegetationacross the full range of land environments in thehighly modified Central Otago region. Several ear-lier studies have examined the patterns of bothwoody and herbaceous vegetation in parts of theenvironmental gradient (e.g., lowland: Hubbard &Wilson 1988; Walker et al. 1995; lowland-montane:Wilson et al. 1989; lowland-subalpine: Partridge etal. 1991; alpine: Mark 1965; Meurk 1982). To com-pile the dataset for our analysis, we drew on the datacollected in these and several unpublished studies(Table 1) that were undertaken for various purposesand therefore reflect different biases. The mostprevalent bias in the pre-existing data was towardssampling more native-species-dominated vegetationat higher elevations. To correct for this, we used

supplementary surveys concentrating on modifiedlowlands to achieve a more environmentally andspatially representative sample of woody vegetationin the dataset.

Analysis of the vegetation pattern across thewhole region resolves and highlights several aspectsof the vegetation that may have been less apparentin vegetation studies at more local scales:1 Climate and human (fire and grazing) disturbanceare the major influences on the current vegetationpattern. Although climate is the main determinant ofthe vegetation pattern across the whole region, fireand subsequent mammalian grazing have been theprimary filters determining species presence or ab-sence at high and low elevations.2 Fragments of the pre-settlement vegetation withintact canopies remain in Central Otago only in a fewscattered refugia in the montane zone. The substan-tial majority of woody plant associations are second-ary and have arisen following the destruction of theoriginal woody vegetation by fire.3 Previous studies of Central Otago vegetationshow strong relationships between secondary plantcommunities and local environmental factors, butlow constancy and fidelity of species within thesecommunities, which were attributed to lack of equi-librium (e.g., Wilson et al. 1989; Partridge et al.1991; Walker et al. 1995). We also found no con-stant or faithful species among our woody plant as-sociations. This may be due to their stochastic origin(the chance invasion of local secondary nativewoody and novel exotic woody species) and/or toinsufficient time since forest destruction for newequilibria to have been reached.

As has long been known, the predominantly her-baceous character of the present-day vegetation ofCentral Otago is not due to extreme climatic condi-tions but, instead, results from the unusual evolution-ary history of the New Zealand flora, which renderedmost indigenous woody species especially vulner-able to fire and grazing following human settlement.If the aim of biodiversity conservation is to main-tain and restore a full range of remaining naturalwoody habitats and ecosystems in Central Otago,and to restore viable populations of indigenouswoody species across their natural range (cf. Minis-try for the Environment & Department of Conser-vation 2000), it is important not only to ensure theprotection of remnants and relicts of the original pre-settlement vegetation, but also to protect and man-age seral woody communities for the long-termrecovery of indigenous woody vegetation across thefull range of land environments, across continuous

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altitudinal sequences from the valley floors to therange tops. Appropriate restoration management forseral woody vegetation will entail the removal ofmammalian herbivores and protection from fire.Where seed sources have been eliminated, these mayneed to be reintroduced, and tall competitive exoticspecies may need to be controlled where appropri-ate.

ACKNOWLEDGMENTS

This work was funded by Department of ConservationS&R (Contract 3205), with additional financial supportfrom the Foundation for Research, Science and Technol-ogy (Contract C09X0205). We are grateful to the MissE. L. Hellaby Indigenous Grasslands Research Trust forfunding summer student scholarships. We thank MichelleBreach, Richard Ewens, Ros Lister, Johanna Nielsen, JoWass, and Gudrun Wells for field assistance and dataentry. We warmly acknowledge several people for gen-erously making their vegetation data available, especiallyPhillip Grove, Cathy Brumley, Mark Stirling, MarilynManning, Katharine Dickinson, James Bibby, BrianRance, Jill Carter, Joy Comrie, Chris Ward, Brent Fagan,Dhana Pillai, Trevor Partridge, Peter Johnson, RalphAllen, Ben Kovacs, J. Bastow Wilson, Peter Wardle, PeterWilliams, Colin Meurk, Graeme Loh, and John Barkla,and thank Peter Wardle, Brian Molloy, and Les Basherfor subfossil data, and Peter Wardle for comments on amanuscript. A large number of Central Otago landown-ers kindly allowed access to their properties for survey,and many staff of the Department of Conservation pro-vided advice and logistic support. We thank ChristineBezar for manuscript editing, and Beverly Elliott, EllyLang, and Belinda Smith-Lyttle for technical support.

REFERENCES

Bibby, C. J. 1997: Macraes Ecological District: surveyreport for the Protected Natural Areas Programme.Wellington, Department of Conservation.

Bliss, L. C.; Mark, A. F. 1974: High-alpine environmentsand primary production on the Rock and PillarRange, Central Otago, New Zealand. New Zea-land Journal of Botany 12: 445–483.

Brumley, C. F.; Stirling, M. W.; Manning, M. S. 1986:Old Man Ecological District: survey report forthe New Zealand Protected Natural Areas Pro-gramme. Wellington, Department of Conserva-tion.

Carter, J. 1994: Waipori Ecological District: survey re-port for the Protected Natural Areas Programme.Wellington, Department of Conservation.

Clifford, H. T.; Stephenson, W. 1975: An introduction tonumerical classification. New York, AcademicPress.

Comrie, J. 1992: Dansey Ecological District: survey re-port for the Protected Natural Areas Programme.Wellington, Department of Conservation.

de Lange, P. J.; Norton, D. A.; Heenan, P. B.; Courtney,S. P.; Molloy, B. P. J.; Ogle, C. C.; Rance, B. D.;Johnson, P. N.; Hitchmough, R. 2004: Threat-ened and uncommon plants of New Zealand. NewZealand Journal of Botany 42: 45-76.

Dickinson, K. J. M. 1988: Umbrella Ecological District:survey report for the Protected Natural AreasProgramme. Wellington, Department of Conser-vation.

Dickinson, K. J. M. 1989: Nokomai Ecological District:survey report for the Protected Natural AreasProgramme. Wellington, Department of Conser-vation.

Ellenberg, H. 1988: Vegetation ecology of central Eu-rope. 4th ed. Translated by G. K. Strutt. Cam-bridge, Cambridge University Press.

Environmental Systems Research Institute 2000: Arc ViewGIS: The Geographic Information System for eve-ryone. Redlands, California, USA, Environmen-tal Systems Research Institute.

Fagan, B.; Pillai, D. 1992: Manorburn Ecological Dis-trict: survey report for the Protected Natural Ar-eas Programme. Wellington, Department ofConservation.

Grove, P. 1992: Hawkdun Ecological District: surveyreport for the Protected Natural Areas Programme.Wellington, Department of Conservation.

Hewitt, A. H. 1998: New Zealand soil classification. 2nded. Lincoln, Manaaki Whenua Press. 133 p.

Hill, M. O.; Gauch, H. G. 1980: Detrended correspond-ence analysis: an improved ordination technique.Vegetatio 42: 47-58.

Hubbard, J. C. E.; Wilson, J. B. 1988: A survey of thelowland vegetation of the Upper Clutha Districtof Otago, New Zealand. New Zealand Journal ofBotany 26: 21-36.

Kelly, G. C.; Park, G. N. ed. 1986: The New ZealandProtected Natural Areas Programme: a scientificfocus: a review in the light of pilot studies and aformat for future action. New Zealand BiologicalResources Centre publication No. 4. Wellington,DSIR.

Leathwick, J. R.; Stephens, R. T. T. 1998: Climate sur-faces for New Zealand. Unpublished LandcareResearch Contract Report LC9798/126. LandcareResearch, Lincoln, New Zealand. 19 p.

Dow

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Page 22: The woody vegetation of Central Otago, New Zealand

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Leathwick, J. R.; Wilson, G.; Rutledge, D.; Wardle, P.;Morgan, F.; Johnston, K.; McLeod, M.;Kirkpatrick, R. 2003: Land environments of NewZealand. Auckland, David Bateman.

Lee, D. E.; Lee, W. G.; Mortimer N. 2001: Where haveall the flowers gone? Depletion and turnover inthe New Zealand Cenozoic angiosperm flora inrelation to palaeogeography and climate. Austral-ian Journal of Botany 49: 341-356.

Lee, W. G. 1998: The vegetation of New Zealand-functional, spatial and temporal gaps. In: Lynch,R. ed. Ecosystems, entomology and plants. TheRoyal Society of New Zealand Miscellaneous Se-ries 48:91-101.

Lister, R. G. 1965: The regional pattern. In: Lister, R. G.;Hargreaves, R. P. ed. Central Otago. Dunedin,New Zealand, New Zealand Geographical Soci-ety. Pp. 9-29.

Mark, A. F. 1965: Vegetation and mountain climate. In:Lister, R. G.; Hargreaves, R. P. ed. Central Otago.Dunedin, New Zealand, New Zealand Geographi-cal Society. Pp. 69-91.

Mark, A. F. 1992: Indigenous grasslands of New Zea-land. In: Coupland R. T.; Goodall D. W. ed.Ecosystems of the world. Vol. 8B. Grasslands.Amsterdam, Elsevier. Pp. 361–410.

Mark, A. F.; Bliss, L. C. 1970: The high-alpine vegeta-tion of Central Otago, New Zealand. New Zea-land Journal of Botany 8: 381–451.

Mark, A. F.; Dickinson, K. J. M. 1997: New Zealandalpine ecosystems. In: Wiegolaski, F. E. ed. Polarand alpine tundra: Ecosystems of the World 3.Amsterdam, Elsevier. Pp. 311-345.

Maunder, W. J. 1965: Climatic character. In: Lister, R.G.; Hargreaves, R. P. ed. Central Otago. Dunedin,New Zealand Geographical Society. Pp. 46-68.

McEwen, W. M. 1987: Ecological regions and districts ofNew Zealand. Wellington, Department of Con-servation.

McGlone, M. S. 1989: The Polynesian settlement of NewZealand in relation to environmental and bioticchanges. New Zealand Journal of Ecology 12(Supplement): 115-129.

McGlone, M. S. 2001: The origin of the indigenousgrasslands of south-eastern South Island in rela-tion to pre-settlement woody ecosystems. NewZealand Journal of Ecology 25: 1-15.

McGlone, M. S.; Wilmshurst, J. M. 1999: A Holocenerecord of climate, vegetation change and peatbog development, east Otago, South Island, NewZealand. Journal of Quaternary Science 14:239-254.

McGlone, M. S.; Mildenhall, D. C.; Pole, M. S. 1996:History and palaeoecology of New ZealandNothofagus forests. In: Veblen, T. T.; Hill, R. S.;Read, J. ed. The ecology and biogeography ofNothofagus forests. New Haven, USA, Yale Uni-versity Press. Pp. 83-130.

McGlone, M. S.; Moar, N. T.; Meurk, C. D. 1997: Growthand vegetation history of alpine mires on the OldMan Range, Central Otago, New Zealand. Arctic& Alpine Research 29: 32-44.

Meigs, P. 1953: World distribution of arid and semi-arid homoclimates. Arid Zone Programme 1:203-210.

Meurk, C. D. 1978: Alpine phytomass and primary pro-ductivity in Central Otago, New Zealand. NewZealand Journal of Ecology 1: 27-50.

Meurk, C. D. 1982: Alpine phytoecology of therainshadow mountains of Otago and Southland,New Zealand. Unpublished PhD thesis, Univer-sity of Otago, Dunedin, New Zealand.

Mildenhall, D. C. 1980: New Zealand Late Cretaceousand Cenozoic plant biogeography: a contribution.Palaeogeography, Palaeoclimatology,Palaeoecology 31: 197-233.

Mildenhall, D. C.; Pocknall, D. T. 1984: Palaeobotanicalevidence for changes in Miocene and Plioceneclimates in New Zealand. In: Vogel, J. C. ed. LateCenozoic palaeoclimates of the Southern hemi-sphere. Rotterdam, AA Balkema. Pp. 159-171.

Ministry for the Environment; Department of Conserva-tion 2000: The New Zealand Biodiversity Strat-egy. Wellington, Department of Conservation.

Ministry for the Environment 2000: New Zealand landcover database. Wellington, Terralink Interna-tional.

Molloy, B. P. J. 1969: Recent history of the vegetation.In: Knox, G. A. ed. The natural history of Canter-bury. Wellington, Reed. Pp. 340-360.

Molloy, B. P. J.; Burrows, C. J.; Cox, J. E.; Johnston, J.A.; Wardle, P. 1963: Distribution of subfossilforest remains, eastern South Island, New Zea-land. New Zealand Journal of Botany 1: 68-72.

Moore, L. B. 1954: Some Rumex acetosella communitiesin New Zealand. Vegetatio 5: 268-278.

Moore, L. B. 1976: The changing vegetation ofMolesworth Station, New Zealand, 1944-71.DSIR Bulletin 217. Wellington, DSIR.

National Water and Soil Conservation Organisation 1979:Our land resources: a bulletin to accompany theNew Zealand Land Resource InventoryWorksheets. National Water and Soil Conserva-tion Organisation, Wellington, New Zealand.

Dow

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Page 23: The woody vegetation of Central Otago, New Zealand

Walker et al.—Woody vegetation of Central Otago 609

O'Connor, K. F. 1982: The implications of past exploita-tion and current developments to the conserva-tion of South Island tussock grasslands. NewZealand Journal of Ecology 5: 97-107.

Ogden, J.; Basher, L.; McGlone, M. S. 1998: Fire, forestregeneration and links with early human habita-tion: evidence from New Zealand. Annals ofBotany 81: 687-696.

Overton, J. McC.; Leathwick, J. R. 2001: Measuringenvironmental distinctiveness. Science for Con-servation 174. Wellington, Department of Con-servation.

Partridge, T. R.; Allen, R. B.; Johnson, P. N.; Lee, W. G.1991: Vegetation/environment relationships inlowland and montane vegetation of the KawarauGorge, Central Otago, New Zealand. New Zea-land Journal of Botany 29: 295-310.

Pole, M. S. 1994: The New Zealand flora—entirely longdistance dispersal? Journal of Biogeography 21:625-635.

Rogers, G. M.; Walker, S. 2002: Taxonomic and ecologi-cal profiles of rarity in the New Zealand vascularflora. New Zealand Journal of Botany 40: 73-93.

Rogers, G. M.; Hewitt, A.; Wilson, J. B. 2000: Ecosys-tem-based conservation strategy for CentralOtago's saline patches. Science for Conservation166. Wellington, Department of Conservation.

Rogers, G. M.; Walker, S.; Tubbs, M.; Henderson, J.2002: Ecology and conservation status of three"spring annual" herbs in dryland ecosystems ofNew Zealand. New Zealand Journal of Botany40: 649-669.

Thornthwaite, C. W. 1948: An approach toward a ra-tional classification of climate. Geographical Re-view 38: 55-94.

Wagstaff, S. J.; Wardle P. 1999: Whipcord hebes -systematics, distribution, ecology and evolution.New Zealand Journal of Botany 37: 17-39.

Walker, S.; Mark, A. F.; Wilson, J. B. 1995: The vegeta-tion of Flat Top Hill-an area of semi-arid grass-land/shrubland in Central Otago, New Zealand.New Zealand Journal of Ecology 19: 175-194.

Walker, S.; Lee, W. G.; Rogers, G. M. 2003: The woodyvegetation of Central Otago, New Zealand: itspresent and past distribution and future restora-tion needs. Science for Conservation 226. Wel-lington, Department of Conservation.

Walker, S.; Lee, W. G.; Rogers, G. M. 2004: Pre-settle-ment woody vegetation of Central Otago, NewZealand. New Zealand Journal of Botany 42:613-646.

Ward, C. M.; Bruce, D. L.; Rance, B. D.; Roozen, D. A.;Grove, P. 1994: Lindis, Pisa and Dunstan eco-logical districts: survey report for the ProtectedNatural Areas Programme. Wellington, Depart-ment of Conservation.

Wardle, P. 1991: The vegetation of New Zealand. Cam-bridge, Cambridge University Press.

Wardle, P. 2001 : Holocene forest fires in the upper Cluthadistrict, Otago, New Zealand. New Zealand Jour-nal of Botany 39: 543-542.

Wilson, J. B. 1975: Teddybear—a statistical system. NewZealand Statistician 10: 36-42.

Wilson, J. B.; Williams, P. A.; Lee, W. G. 1989: Vegeta-tion composition and segregation in relation tothe environment at low altitudes in the UpperClutha Basin, New Zealand. New Zealand Jour-nal of Ecology 12: 103-116.

Appendix 1 over page

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Appendix 1 Environmental factors used in the analysis of present-day vegetation patterns, derivation, and range inCentral Otago.

Factor Derivation Range

Climate factorsMean annual temperature

Temperature seasonality

Rainfall :potentialevapotranspiration ratioOctober vapour pressure deficit

Penman annual precipitationdeficitMean annual solar radiation

Solar radiation seasonality

Soil factorsSoil age since last major resetof soil formation

CalciumAcid soluble phosphateParticle sizeSalinityDrainage

OtherPredominant slope or relief

Climate surfaces1

T-T

where J = July minimum temperature,T– = annual temperature,/ = mean ofJ,Gj= standard deviation ofJ, etc.

Total annual rainfallTotal annual potential evapotranspirationMean October air saturation deficitat 0900 hoursTotal annual potential evapotranspiration- total annual precipitation

T-T

where J = June solar radiation,S = annual solar radiation,Etc. as for Temperature seasonality

NZLRI2

1 = preglacial, 2 = 2000 yearsto postglacial, and 3 = younger than2000 years1 (low) to 4 (high)1 (low) to 5 (high)1 (clay) to 5 (massive)1 (low) to 4 (high)1 = Very poor, 2 = Poor, 3 = Impeded,4 = Moderate, 5 = Good

Min 1.3°CMax 10.7°C

Min -3.99°C

Max 3.56°C

Min 0.592Max 2.709Min 0.144 kPaMax 0.539 kPaMin 0 mmMax 887 mmMin 124 MJ m–2 d–1

Max 141 MJ m–2 d–1

Min -0.99 MJ m–2 d–1

Max 0.33 MJ m–2 d–1

Min0°Max 40°

1 Leathwick & Stephens (1998).2 New Zealand Land Resource Inventory (National Water and Soil Conservation Organisation 1979).

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Appendix 2vegetation.

Data sources, authors, and collectors of the floristic database used in the analysis of present-day woody

Base presence/absence dataset No. records Reference

Dunstan PNA surveyDansey PNA surveyHawkdun PNA surveyClutha Valley survey1

Kawarau Gorge survey1

Lindis PNA surveyManorburn PNA surveyMacraes PNA surveyOtago alpine phytoecology1

Nokomai PNA surveyOld Man PNA surveyPisa PNA surveyRabbit and Land Management Programme1

Rock and Pillar surveyUmbrella PNA surveyUpper Clutha survey1

Waipori PNA survey

Supplementary presence/absence datasetCentral Otago survey plotsCentral Otago survey point observations

164123156142233661259011194628114106120188281442632

86910971966

Ward et al. (1994)Comrie (1992)Grove (1992)Hubbard & Wilson (1988)Partridge et al. (1991)Ward et al. (1994)Fagan & Pillai (1992)Bibby (1997)Meurk (1982); C. D. Meurk unpubl. dataDickinson (1989)Brumley et al. (1986)Ward et al. (1994)K. Colhoun et al. unpubl. dataB. Kovacs and K. J. M. Dickinson unpubl. dataDickinson (1988)Wilson et al. (1989)Carter (1994)

Walker et al. 2003Walker et al. 2003

size differs from standard 10 X 20 m.

Appendix 3 The number of records of regionally rare and local woody species (2-12 database records) in CentralOtago, classified into nine groups (Gp, i to ix) according to their presence within the sample plots of the 14 woodyplant associations (A to N). Four categories of woody vegetation are recognised: 1, montane forests and forest relicts;2, associations of intermontane basin floors and range toeslopes; 3, associations of montane and subalpine rangeslopes; and 4, associations of upper slopes and range tops.

Woody vegetation category

Gp D G H K M N

Native speciesi Clematis paniculata 3

Elaeocarpus hookerianus 2ii Olearia hectorii

Carmichaelia corrugataOlearia ilicifoliaPittosporum eugenioidesPennantia corymbosaTeucridium parvifolium

iii Coprosma aff. pseudocuneataFuchsia perscandensOlearia fimbriataClematis quadribracteolata

1

211131

14 1

1 1

2

111

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Appendix 3 (Continued)

Woody vegetation category

Gp D G H K M N

iv Parsonsia heterophyllaMyrsine australisRubus squarrosusAristotelia serrataRubus australisMelicytus ramiflorusCarmichaelia arborea

v Cyathodes empetrifoliavi Hebe petrieivii Brachyglottis cassinioides

Pimelea pulvinarisviii Solanum laciniatumix Hebe hectorii var. demissa

Hebe tetrasticha

Exotic speciesi Acer pseudoplatanus

Ribes sanguineumLarix deciduaSalix baby lonicaFraxinus excelsiorRosa micranthaLeycesteria formosa

iv Prunus spp.Buddleja davidiiCotoneaster franchetiiCotoneaster glaucophyllusBetula pendulaPrunus aviumPrunus mahalebCupressus macrocarpa 1

542112

3341

2 2 11 1

Regionally rare native species recorded in unclassified plots: Aristotelia fruticosa x A. serrata, Carmichaeliacurta, Coprosma lucida, C. niphophila, C. serrulata, Dracophyllum kirkii, D. prostratum, D.prostratum x uniflorum,Exocarpus bidwillii, Halocarpus biformis, Hebe aff. rakaiensis, H. cockayneana, H. cupressoides, H. hectorii var.subulata, H. treadwellii, Hoheria angustifolia, Neomyrtus pedunculata, Pittosporum divaricatum, Pseudopanaxarboreus, Ripogonum scandens, Schefflera digitata, UrticaferoxRegionally rare exotic species recorded in unclassified plots: Acer campestre, Cotoneaster lacteus, C. simonsii,Hedera helix, Ilex aquifolium, Ligustrum japonicum, Prunus domesticus, Robinia pseudoacacia, Solanum dulcamara

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