rain forest vegetation of 'eua island, kingdom of tongaconsists of older, raised limestone...

New Zealand Journal of Botany, 1996, Vol. 34: 65-770028-825X/96/3401-065 $2.50/0 © The Royal Society of New Zealand 1996

65

Rain forest vegetation of 'Eua Island, Kingdom of Tonga

DONALD R. DRAKEBiology DepartmentGeorgia Southern UniversityLandrum Box 8042Statesboro, GA 30460, USA

Present address: School of Biological Sciences,Victoria University of Wellington, P. O. Box600, Wellington, New Zealand

W. ARTHUR WHISTLERTIMOTHY J. MOTLEY

Botany DepartmentUniversity of Hawai'iHonolulu, HI 96822, USA

CLYDE T. IMADABotany DepartmentBernice P. Bishop MuseumP.O.Box 19000-AHonolulu, HI 96817, USA

Abstract The indigenous vegetation of 'Eua Is-land, Tonga, is described and a species list presented.Quantitative data were collected from 40 forest plotsin which all vascular plant species were recorded andthe diameters of all stems > 5 cm dbh were meas-ured. Plot classification, based on basal area data,identified six forest types, two coastal and four in-land, which reflect an elevational sequence from thecoast to the island's summit (312 m a.s.l.). A polarordination, based on basal area data, arranged plotsfrom the four inland forest types in a sequence fromlow to high elevation along one ordination axis, andfrom more mature to less mature along a second axis.Species richness increased with elevation. Severaladditional, non-forest vegetation types, includingfern- and grass-dominated vegetation of inland

B95023Received 17 May 1995; accepted 27 October 1995

ridges and shrub-dominated vegetation of cliffs androcky shores, were sampled semi-quantitatively andare also described.

Keywords 'Eua; Pacific Islands; rain forest;Tonga; flora; vegetation

INTRODUCTION

The Kingdom of Tonga consists of two parallelchains of islands that run roughly north and south,between 15-23° S latitude and 173-176° W longi-tude in the South Pacific Ocean (Fig. 1). Thesparsely-inhabited western chain consists of rela-tively young, active, mainly andesitic volcanoes upto 1030 m a.s.l. The densely-inhabited eastern chainconsists of older, raised limestone islands up to312 m a.s.l.

To date, there have been few published descrip-tions of the vegetation of Tonga. Uhe (1974) andSykes (1981) have described the vegetation of thevolcanic islands of Niuafo'ou and Late, respectively.The coastal communities of several small islets inthe Tongatapu (Stoddart 1975; Ellison 1990) andHa'apai (Woodroffe 1983) groups have been de-scribed. Palmer (1988) surveyed the least disturbedrelictual stand of inland forest on the limestone is-land of Tongatapu. Straatmans (1964) and Sykes(1978) have published brief, qualitative descriptionsof the vegetation of'Eua, which is Tonga's highest,oldest, and least disturbed large, limestone island.Whistler (1992) has reviewed the vegetation of Sa-moa and Tonga.

Although 'Eua has long been reputed to supportthe richest, most unique forest in Tonga (Sykes1978), no detailed, quantitative description of 'Eua'sforest vegetation has ever been published. The rapidrate of forest clearing on 'Eua has recently begun tothreaten its remaining stands of indigenous forest(Allen 1990), increasing the need for such a descrip-tion for scientific and conservation purposes. Thepurpose of this study was to describe the composi-tion and distribution of the indigenous vegetation of

66 New Zealand Journal of Botany, 1996, Vol. 34

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Fig. 1 Map of the major islands of Tonga and of thefive physiographic provinces on 'Eua (after Hoffmeister1932) : 1) the eastern terraces and coastal region, 2) theeastern ridge, 3) the dissected, western slope of the east-ern ridge, 4) the western ridge and central valley, and5) the western slope terraces and coastal region.

'Eua. A summary of the preliminary analysis of thedata (Drake et al. 1990) was supplied to the TonganGovernment and was used as a basis for establish-ing a national park on 'Eua in 1992.

STUDY AREA

Geology and soils'Eua is a high island, roughly 81 km2 in area, whosesurface rises gradually from the west coast as a se-ries of distinct terraces, to a high eastern ridge witha maximum elevation of 312 m a.s.l. (Hoffmeister1932; Bryan et al. 1972; Wilde & Hewitt 1983) (Fig.

1). East of the ridge, a series of steep cliffs, inter-rupted by narrow terraces, leads to the coast. Muchof the terraced relief is the result of periodic, geo-logic uplifting of the island. Hoffmeister (1932)mapped five physiographic provinces on 'Eua: 1) theeastern terraces and coastal region, 2) the easternridge, 3) the dissected, western slope of the easternridge, 4) the western ridge and central valley, and5) the western slope terraces and coastal region.

Although most of its surface is covered by lime-stone, 'Eua is unique among Tonga's limestone is-lands in that its core consists of volcanic rocks, andthese form exposed outcrops along the eastern ridgeand eastern cliffs (Hoffmeister 1932; Bryan et al.1972). Overlying the core, and forming additionaloutcrops along the eastern ridge and its margins, isa layer of Eocene foraminiferal and algal limestones.Overlying the Eocene limestones on the eastern ridgeand its western slopes are Miocene submarine tuffsand tuffaceous limestone. Late Tertiary coral reeflimestone comprises the bulk of the western ridgeand central valley, and forms minor terraces alongboth coasts. Quaternary andesitic tephra forms alayer up to 2 m thick over most of the island, exceptin steep areas where it has been removed by erosion.

Most soils are derived from the young andesitictephra with or without additional volcanic alluviumfrom older tephras (Wilde & Hewitt 1983). Deeply-weathered soils from the tuffs comprising the coreare found where the core forms outcrops along theeastern ridge. Volcanic and calcareous parent mate-rials combine to form colluvial soils on steep slopesand at the bases of cliffs. Elsewhere, calcareousmaterials are not involved in soil formation, exceptas unconsolidated sand along the coasts. Develop-ment of distinct soil horizons decreases, andevidence of continual soil development due to down-slope movement increases, with increasing steepnessof slope. The majority of'Eua's soils are alfisols andmollisols, with inceptisols on the steep (> 30°) slopesand entisols (coralline sands) along some coasts(Wilde & Hewitt 1983).

Climate'Eua lies within the south-east tradewind zone, andwinds blow from the easterly quadrant 65-75% ofthe time. Mean annual rainfall is approximately2700 mm, of which roughly 2A falls during the wetseason of November to April (Thompson 1986).There is little seasonal variation in temperature.Sykes (1978) has remarked that the microclimatenear the summit ridge appears cooler and moisterthan that at lower elevations.

Drake et al.—Forest vegetation of 'Eua Island, Tonga 67

METHODS

Data collectionIn June and July 1990, forest vegetation was sam-pled in forty 600 m2 plots (mainly 20 x 30 m), eachlocated in a stand of forest representative of thatfound in the surrounding area. Stands that had obvi-ously been disturbed by humans were avoided. Foreach plot, the precise location (on topographic mapand aerial photo), elevation, aspect, slope, substrate(bare sand, limestone, volcanic soil), and canopyheight were determined and all vascular plant spe-cies were recorded. A species list is presented inAppendix I. For all trees, diameters of all stems >5 cm diameter at breast height (dbh) were measured.For individuals < 5 cm dbh, as well as shrubs, herbs,epiphytes, and lianas, a Braun-Blanquet semi-quantitative estimate of cover was made for eachspecies in each of several strata: shrub (c. 1 —3(—5)m), ground cover (< 1.0 m), epiphyte, and liana(Mueller-Dombois & Ellenberg 1974). Braun-Blanquet, semi-quantitative cover estimates werealso made in seven 600 m2 plots in non-forest veg-etation. Detailed notes on species distribution andforest composition were also compiled for sites notsampled quantitatively. Most of the plots were lo-cated in the most extensive tracts of undisturbedforest along the eastern coast and terraces, the east-ern ridge, and the steep ravines of the western slopeof the eastern ridge. A few additional plots werelocated in smaller, disjunct stands of indigenousvegetation scattered throughout the island.

Data analysisRelative basal area data for the 86 tree species re-corded in the 40 plots that were sampled quantita-tively were analysed using two-way indicator speciesanalysis (TWINSPAN, Hill 1979) to identify speciesassociations. Relative basal area data for 35 inlandforest plots were also analysed using a Bray-Curtispolar ordination (ORDIFLEX, Gauch 1979) to iden-tify gradients in species composition. The fivecoastal forest plots on coralline sands and raisedlimestone benches were excluded from the ordina-tion because their dissimilarity to the 35 inland plotsresulted in poor separation among the inland plots.End points of the first axis were the two plots thatwere most dissimilar to each other; end points of thesecond axis were the two remaining plots that weremost dissimilar to each other and had first axis scoresbetween 40 and 60.

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Fig. 2 Dendrogram derived from two-way indicator spe-cies analysis (TWINSPAN) classification of 40 forestplots, using relative basal area of tree species. Romannumerals represent the following vegetation types: I.Excoecaria-Tournefortia coastal forest, II. Hernandia-Terminalia coastal forest, III. Maniltoa-Pleiogynium low-land rain forest, IV. Myristica lowland rain forest, V.Calophyllum mixed upland rain forest, VI. Calophyllum-Garcinia upland rain forest. The elevational range overwhich each type occurs is indicated at the right.

RESULTS

TWINSPAN identified six ecologically interpretablegroups of plots at the third level of classification,with the three largest groups being divided into threeadditional subtypes at the fourth level (Fig. 2). Oneplot (no. 34), containing a large, outlying coastal tree,was misclassified by TWINSPAN and, in the com-munity descriptions below, is grouped based on its


position in the ordination. In general, TWINSPANordered the plots into groups reflecting a topographicsequence from the coast to the summit ridge. Char-acteristics of the six community types and theirvariants are outlined below. In the following descrip-tions, species within a given stratum are listed inorder of decreasing relative basal area (trees) orBraun-Blanquet cover values (smaller species). Forthe dominant species, mean relative basal area (rba)and maximum dbh are given in parentheses (% rba,diam. cm).

I. Excoecaria-Tournefortia coastal forest is found atelevations < 5 m a.s.l. on raised limestone substratesthat lack sand or soil. It exists in small, disjunctpatches that combine to form a narrow band alongthe coast, though they rarely extend more than 20 minland. There is often no beach along the seawardmargin of these forest patches, and therefore expo-sure to waves and salt spray, particularly duringstorms, must be great. Species richness is low.

Excoecaria agallocha (48%, 69 cm) and Tourne-fortia argentea (syn. Argusia argentea) (40%,75 cm) dominate the canopy. Both are multi-stemmed trees that reach a height of 12 m. Hibiscustiliaceus, another multi-stemmed tree, forms a some-what lower middle stratum, which often includesNeisosperma oppositifolium, Schleinitzia insularum,and Morinda citrifolia. The shrub stratum containsscattered individuals of Bikkia tetrandra, Wollas-tonia biflora, Clerodendrum inerme, and Scaevolasericea, all of which are much more abundant in thestrand vegetation (type VII) on the seaward marginof this forest. Terrestrial herbs, epiphytes, and lianasare rare.

II. Hernandia-Terminalia coastal forest is found atelevations < 5 m a.s.l. on sand substrates. Althoughthis forest is somewhat sheltered behind sandbeaches and strand vegetation, it is presumablystrongly influenced by salt spray, and occasionallyby large storms such as cyclone 'Ofa, which hadobviously disturbed the understory of many littoralforest sites in January 1990. Species richness isgreater than in the Excoecaria-Tournefortia coastalforest.

The upper canopy is dominated by Hernandianymphaeifolia (31%, 90 cm) and/or Terminaliacatappa (25%, 122 cm). Other common, large (>40 cm dbh) canopy trees include Terminalialitoralis, Guettarda speciosa, Planchonella grayana,Schleinitzia insularum, Hibiscus tiliaceus, Myristicahypargyraea, and Pisonia grandis; Cocos nucifera

occurs in the canopy in places. The subcanopy isoverwhelmingly dominated by Neisospermaoppositifolium, which can occasionally exceed50 cm dbh, plus lesser amounts of Cordiasubcordata (only on the northwest coast), andGrewia crenata. A lower stratum contains Pandanustectorius, Xylosma simulans, Cycas rumphii, andVavaea amicorum. The only common terrestrial herbis the fern Phymatosorus grossus, and epiphytes arerare. Lianas are sparse, the most common ones be-ing Epipremnum pinnatum, Hoya australis, Fara-day a amicorum, and Jasminum didymum.

III. Maniltoa-Pleiogynium lowland rain forest occursonly in the north-western quarter of the island alongthe western slope terraces and coastal region. Thisvegetation begins at the landward edge of the litto-ral forest, where sand or exposed limestone givesway to volcanic soils overlying limestone, and con-tinues inland up to elevations of 60 m, on slopesranging from 11-20°.

Here Myristica hypargyraea and Neisospermaoppositifolium, the dominant species of lowland rainforests over the rest of the island (see below), arecompletely absent. Instead, the dominant species areManiltoa grandiflora (49%, 56 cm) and Pleiogyniumtimoriense (17%, 56 cm). Other large trees (> 35 cmdbh) include Sapindus vitiensis and Aleuritesmoluccana. The subcanopy contains Chionanthusvitiensis, Xylosma simulans, Vavaea amicorum, andDiospyros samoensis. A lower stratum containsCryptocarya hornei, Cycas rumphii, Memecylonvitiense, Micromelum minutum, Rhamnella vitiensis,and the shrub Graptophyllum insularum. The mostcommon terrestrial herb is Asplenium polyodon.Lianas comprise 29% of the species in the flora andare abundant, especially Entada phaseoloides,Jasminum simplicifolium, Alyxia stellata, Jasminumdidymum, Gynochtodes epiphytica, and Malaisiascandens.

IV. Myristica lowland rain forest begins at the land-ward edge of the coastal forest, where sand or ex-posed limestone gives way to volcanic soilsoverlying limestone, and continues inland up to el-evations of 110 m, on slopes ranging from 0-33° ormore. It is found along the eastern slopes and ter-races, western slope terraces, and coastal region,everywhere except in the north-western quarter ofthe island.

Myristica hypargyraea (53%, 97 cm) is the over-whelming dominant in this forest type, where noother species averages more than 13% rba. It is a


large tree, reaching a height of 25 m, and is usuallypresent in all size classes. Occasional large (> 40 cmdbh) individuals of Pleiogynium timoriense,Maniltoa grandiflora, Guettarda speciosa,Canarium harveyi, Diospyros samoensis,Planchonella grayana, and Calophyllum neo-ebudicum are also scattered through this forest type.The subcanopy contains Neisosperma oppositifoliumand Xylosma simulans. A lower stratum often in-cludes Diospyros samoensis, Hibiscus tiliaceus,Citronella samoensis, Cycas rumphii, and the shrubMacropiper puberulum. Herbaceous species areuncommon, with little cover. Asplenium austral-asicum is occasionally present as an epiphyte. Lianascomprise 25% of the flora, the most abundant spe-cies being Faraday a amicorum, Connarus sp. nov.,Epipremnum pinnatum, Alyxia bracteolosa, Entadaphaseoloides, Jasminum simplicifolium, Gyno-chtodes epiphytica, and Jasminum didymum.

In places (plots 9, 14), this forest type appears tobe in a state of recovery from some past disturbance;here the leading dominant is Dendrocnide harveyi(57%, 112 cm). Dendrocnide harveyi saplings do notoccur in the understory beneath a closed canopy ofmature trees. Myristica hypargyraea is codominantin the upper stratum and abundant in the lower strata.

V. Calophyllum mixed upland rain forest occurs onvolcanic soils overlying the limestone of the uppereastern terraces, the western slope of the easternridge, and upper portions of the ridge and ravinesystem of the central valley, at elevations of 100-180(-240) m, on slopes of 2-45°. The tree strata arequite rich here, and no one species comprises, onaverage, more than 12% of the relative basal area inthis forest. Of the 15 plots classified into this type,eight different species were the leading dominant inat least one plot, and no one species was the leadingdominant in more than three plots.

The most consistently abundant large tree is Calo-phyllum neo-ebudicum (11%, 91 cm); it is presentin all plots, reaches a height of 35 m, and is typicallyrepresented in all size classes. Dysoxylum tongense(12%, 171 cm) is the most common co-dominant,and is present in 80 % of the plots. Other commoncanopy species (> 50 cm dbh) are Elattostachysfalcata, Canarium harveyi, Myristica hypargyraea,Alphitonia zizyphoides, Maniltoa grandiflora, Neo-nauclea forsteri, Semecarpus vitiensis, Litseamellifera, and Dysoxylum forsteri. The subcanopycontains large amounts of Diospyros samoensis,Cryptocarya hornei, Garcinia myrtifolia, andCitronella samoensis. The lower stratum includes

Vavaea amicorum, Cryptocarya turbinata,Hedycarya dorstenioides, and Psychotria carnea,and large amounts of the shrub Macropiperpuberulum. The herb layer is well-developed, and isdominated by the ferns Tectaria dissecta, Christellaparasitica, Pteris comans, and Arachnoides aristata;the ground orchid Corymborkis veratnfolia is alsocommon. Asplenium australasicum is occasionallypresent as an epiphyte. Lianas comprise 23% of theflora and are extremely abundant, especially Entadaphaseoloides, Alyxia bracteolosa, Embelia vaupelii,Jasminum simplicifolium, Connarus sp. nov., Epi-premnum pinnatum, Melodinus vitiensis, Jasminumdidymum, and Gynochtodes epiphytica.

In places, this forest type appears to be in a stateof recovery from some past disturbance, and here theleading dominants are either Dendrocnide harveyi(55%, 95 cm) with Bischofiajavanica (24%, 56 cm)(plots 7 and 8), or Rhus taitensis alone (65%, 99 cm)(plots 6, 23, and 24). Where present, these speciescombine to form > 65% of the relative basal area,though they are absent from all smaller size classes,which are instead dominated by the other tree spe-cies common to the Calophyllum mixed forest.

VI. Calophyllum-Garcinia upland rain forest occurson volcanic soils overlying limestone, at elevationsof 190-300 m, on slopes of 5^0° . It is found up-slope of the Calophyllum mixed forest and reachesits greatest development mainly on the steep slopesnear the summit of the eastern ridge.

Here, in contrast to the Calophyllum mixed for-est below, the upper canopy is more strongly andconsistently dominated by Calophyllum neo-ebudicum (27%, 76 cm), which is typically repre-sented in all size classes. Other common large (>40 cm dbh) trees include Neonauclea forsteri,Homalium whitmeeanum, Canarium harveyi, Podo-carpus pallidus, Dysoxylum tongense, Elaeocarpusgraeffei, Hernandia moerenhoutiana, Myristicahypargyraea, and Rhus taitensis. The subcanopy isalmost completely dominated by Garcinia myrtifolia(15%, 32 cm), which can occur at densities of morethan 50 trees per plot; it is consistently representedin all size classes. The lower stratum containsVavaea amicorum and the shrubs Macropiper

puberulum, Ixora calcicola, Cordylinefruticosa, andPhaleria glabra. The herbaceous layer is well-de-veloped and the most common elements are the fernsArachnoides aristata, Pteris comans, Schizaeadichotoma, and Christella parasitica. Aspleniumaustralasicum and Robiquetia bertholdii are com-mon epiphytes. Lianas are extremely abundant,


especially Faradaya amicorum, Smilax vitiensis,Alyxia bracteolosa, Jasminum simplicifolium,Freycinetia urvilleana, Alyxia stellata, Hoyaaustralis, and Embelia vaupelii.

In places (plots 2, 18, 35) where this forest typeappears to be in a state of recovery from some pastdisturbance, the leading dominants are Alphitoniazizyphoides (33%, 76 cm) and Elattostachys falcata(11 %, 48 cm). These are absent from the smaller sizeclasses, which are instead dominated by the othertree species common to Calophyllum-Garcinia for-est. Alphitonia zizyphoides is less common outsidedisturbed upland forest, but E. falcata is often presentin low numbers throughout the upland rain forest.

Other types of vegetation, sampled semi-quantita-tively, include:

VII. Strand vegetation: The species composition ofthe strand vegetation, like that of the adjacent coastalforest, is determined largely by the substrate. Sea-ward of the Excoecaria-Tournefortia coastal forest,and elsewhere on other bare, raised limestonebenches, the vegetation consists of a shrubby layerdominated by Bikkia tetrandra, Scaevola sericea,Clerodendrum inerme, and Wollastonia biflora, witha ground layer of succulent species such as Pemphisacidula, Sesuvium portulacastrum, and the parasiticvine Cassythafiliformis. Seaward of the Hernandia-Terminalia coastal forest, on sand, trees includescattered individuals of Cocos nucifera, Tournefortiaargentea, Acacia simplex, and Sophora tomentosa.The most common shrubs are Scaevola sericea andWollastonia biflora, and the ground layer containsIpomoea pes-caprae. On some sandy shores, the treeSchleinitzia insularum forms small, monospecificstands.

VIII. Cliff vegetation: The upper cliffs of the east-ern ridge are covered in many places by a smoothcanopy of wind-swept vegetation, 3-5 m high. Com-mon species include Diospyros elliptica, Citronellasamoensis, Maesa tongensis, Badusa corymbifera,Maytenus vitiensis, and many others. At lower eleva-tions, where the eastern cliffs are very steep andrelatively exposed to salt spray, the vegetation isopen-canopied and dominated by Pandanustectorius, and, in the south-east, by Pritchardiapacifica. Where the cliffs are less steep, though stillexposed to spray, there is a low forest of Hibiscustiliaceus, Myristica hypargyraea, Neisospermaoppositifolium, Pandanus tectorius, Terminaliacatappa, Schleinitzia insularum, and Cycas rumphii.

Fig. 3 Bray-Curtis polar ordination of 35 inland forestplots of 'Eua, using relative basal area of tree species.Roman numerals represent the following vegetation types:III. Maniltoa-Pleiogynium lowland rain forest, IV.Myristica lowland rain forest, V. Calophyllum mixed up-land rain forest, VI. Calophyllum-Garcinia upland rainforest.

IX. Monospecific clonal stands: At lower and mid-dle elevations, Hibiscus tiliaceus often forms exten-sive (> 1000 m2), nearly monospecific stands thatappear to have arisen through clonal growth. Thestands are characterised by numerous stems grow-ing in many planes and creating dense thickets. Atmiddle and high elevations, multi-stemmed, clonalindividuals of the banyan Ficus obliqua occasion-ally cover areas in excess of 1000 m2, to the exclu-sion of most other woody species. The upperbranches of the banyans support large numbers ofthe fern Asplenium australasicum.

X. Toafa (treeless) vegetation: Toafa vegetationoccurs on deeply weathered soils on exposed, vol-canic ridges. Although the exact composition of thetoafa patches varies from place to place, the physi-ognomy is very consistent. A mixture of grasses,pteridophytes, and scattered woody species forms anupper stratum 0.5—1.5 m tall, beneath which numer-ous herbaceous and semi-woody species are found.Common species include the grasses Miscanthusfloridulus and Paspalum conjugatum, the pterido-phytes Dicranopteris linearis, Sphaerostephanosunitus, and Lycopodium cernuum, and the woody


<50 100-149 200-24950-99 150-199 >249

Elevation (m)

20

10

M. hypargyraea C. neo-ebudicum

Fig. 4 Basal area of two dominant species of trees(Myristica hypargyraea and Calophyllum neo-ebudicum)at various elevations. (Community types IV, V, and VI,only; number of plots = 3, 3, 6, 10, 7, and 3, from left toright).

species Wikstroemiafoetida, Alphitonia zizyphoides,Psidium guajava, and Melastoma denticulatum. Themean number of species in five 600 m2 plots was26.4.

TrendsResults of the ordination corresponded well with theTWINSPAN analysis. Three of the major inlandcommunities were spread, with little overlap, alongthe first axis (Fig. 3). An exception was one inlandcommunity (Maniltoa-Pleiogynium lowland forest),which appeared at the center of the ordination, be-cause it lacked the dominant species of the plots thatformed the end points.

The first axis score was positively correlated withelevation (first axis ordination score = 0.24 x plotelevation (m) + 15.3, n = 35, r2 = 0.52, P < 0.001).This trend is further illustrated by the shift in domi-nance from Myristica hypargyraea to Calophyllumneo-ebudicum with increasing elevation in commu-nities IV, V, and VI (Fig. 4). Species richness in theforest plots increased with increasing elevation (n =40, r2 = 0.38, P < 0.001; Fig. 5), with plots near thesummit of the eastern ridge having approximatelytwice as many species as occurred in plots near sealevel. The second ordination axis appeared to cor-respond to degree of disturbance, with vegetationsubtypes judged to be recovering from some pastdisturbance occurring high on the second axis, andolder stands occurring lower (Fig. 3).

0 50 100 150 200 250 300Elevation (m)

Fig. 5 Regression of species richness (number of vas-cular plant species per 600 m2 plot) vs. plot elevation forthe 40 forest plots on 'Eua.

DISCUSSION

'Eua supports a variety of plant communities; someare relatively widespread throughout Western Poly-nesia, while others may be found nowhere else in thePacific.

In general, 'Eua's coastal vegetation is similar tothat found in strand habitats throughout the tropicalSouth Pacific. Species such as Hernandia nymphaei-

folia, Terminalia spp., Tournefortia argentea, andScaevola sericea are common coastal dominantselsewhere in Tonga (Stoddart 1975; Woodroffe1983; Ellison 1990), as well as in Nauru and Kiribati(Thaman 1992), Tuvalu (Woodroffe 1986, 1991),Wallis, Futuna, and Alofi (Morat & Veillon 1985),Fiji (Garnock-Jones 1978; Kirkpatrick & Hassall1981; Ash 1992), Samoa (Whistler 1980, 1983),Tokelau (Parham 1971), and the Cook Islands (Mer-lin 1991; Franklin & Merlin 1992). In contrast,Excoecaria agallocha appears to be of limited im-portance outside Tonga.

Similarly, the treeless, toafa vegetation dominatedby ferns (e.g., Dicranopteris linearis) and grasses(e.g., Miscanthus floridulus) frequently noted on'Eua(Straatmans 1964; Sykes 1978; Whistler 1992)is also common on poor, volcanic soils elsewhere inthe South Pacific. It occurs in Vanuatu (Schmid1975), Wallis, Futuna, and Alofi (Morat & Veillon1985), Fiji (Garnock-Jones 1978; Ash 1992), Samoa(Whistler 1980), the Cook Islands (Sykes 1978;Merlin 1985,1991), and the Society Islands (Fosberg1992).

'Eua's secondary forests share many pioneer spe-cies with disturbed forests of other islands. For ex-


ample, Alphitonia zizyphoides, Rhus taitensis, andElattostachys falcata are among the dominants onthe relatively young volcanic island of Late, and thelatter two are dominant in the last relictual stand ofinland forest on the limestone island of Tongatapu(Palmer 1988). Straatmanns (1964) first describedthe dynamic relationship among 'Eua's canopy trees.He noted that seedlings of A. zizyphoides, R. taiten-sis, and E. falcata did not grow in dense forest,whereas seedlings of Calophyllum neo-ebudicumand Myristica hypargyraea did. In addition, A. zizy-phoides, R. taitensis, and E. falcata, together withDendrocnide harveyi and Bischofia javanica, areimportant components of secondary forests inVanuatu (Schmid 1975), Wallis, Futuna, and Alofi(Morat & Veillon 1985), and Samoa (Whistler1980).

In contrast to the secondary forests, 'Eua's old-growth inland rain forests bear little similarity tothose of other regional islands. Several factors mayaccount for the uniqueness of 'Eua's rain forests.Because the number of plant taxa in the Pacific gen-erally decreases with increasing distance fromMalesian source areas (van Balgooy 1971; Fosberg1984; Stoddart 1992), nearly every island or smallarchipelago has a somewhat unique flora and, there-fore, vegetation. Large islands north and west ofTonga contain many of the dominant species of'Eua's mature rain forest, however, these species arenot dominant in these richer forests. For example,Samoa's Syzygium lowland forest is dominated bySyzygium inophylloides (uncommon on 'Eua), butalso contains substantial amounts of two Tongandominants, Myristica hypargyraea and Calophyllumneo-ebudicum (Whistler 1992). In upland forests onMt. Korobaba, Fiji, Calophyllum neo-ebudicum andGarcinia myrtifolia are common, but not dominant(Kirkpatrick & Hassall 1985). Islands east of Tonga,such as the Cook Islands, simply lack many of theTongan dominants (Merlin 1985, 1991; Franklin &Merlin 1992). Stoddart (1992) states that "there isno more dramatic biogeographic boundary in thePacific than that between the southern Cooks and thesouthern Tongan islands." This discontinuity is atleast partly a reflection of 'Eua's position on theeastern margin of the continental Indian-AustralianPlate.

Other, non-biogeographic factors also contributeto 'Eua's uniqueness. Due to their combination oflimestone substrate, elevation, and relief, raisedlimestone islands such as 'Eua, Makatea, andMangaia tend to have distinctive floras (Stoddart1992). As a result, their vegetation bears little

similarity to that of nearby volcanic or low coral is-lands. Thus, 'Eua's forests differ from those of thevolcanic islands in Tonga, such as Late. Sykes(1981) noted Casuarina equisetifolia, Alphitoniazizyphoides, Elattostachys falcata, and Rhus taitensisas dominant and Calophyllum neo-ebudicum as com-mon on Late; in contrast, Myristica hypargyraea,Maniltoa grandiflora, Dysoxylum spp., and Garciniamyrtifolia were absent.

Even among raised limestone islands, 'Eua isrelatively unique in its combination of great eleva-tion (312 m a.s.l.), large surface area (81 km2), age(Eocene), sharp relief, deep andesitic soils, and vol-canic core. Only 'Uta Vava'u in northern Tonga hasthe proper combination of biogeographic position,size (95 km2), elevation (210 m), and andesitic soilsover limestone (Orbell et al. 1985) to potentiallysupport rain forest vegetation similar to 'Eua's.However, 'Uta Vava'u's vegetation is quite distinctbecause many of the dominant species of 'Eua'sforests are rare or absent there (J. Franklin & D.Drake unpubl. data). Given the uniqueness of'Eua'srain forest vegetation, the Tongan Government de-serves praise for the foresight they have demon-strated through their ongoing efforts to protect a largetract of it in a national park.

ACKNOWLEDGMENTS

This study was funded by a grant from the Pacific IslandsDevelopment Program and the Program on the Environ-ment of the East-West Center in Honolulu, Hawaii. TheTongan Government, including the Ministry of Agricul-ture, Forestry, and Fisheries and the Ministry of Landsand Surveys facilitated our efforts throughout the project.M. Pomelile, M. Thomas, M. Sau, and K. Siakumi pro-vided valuable assistance in the field. The manuscriptbenefitted greatly from the critical comments of J. Ash,J. Franklin, F. Kell, A. McGee, and an anonymous re-viewer.

REFERENCES

Allen, R. B. 1990: Tongan forestry subsector study. Un-published report. Christchurch, Forest ResearchInstitute.

Ash, J. 1992: Vegetation ecology of Fiji: Past, present,and future perspectives. Pacific science 46: 111—127.

van Balgooy, M. M. J. 1971: Plant-geography of thePacific. Blumea supplement 6: 1—222.


Bryan, W. B.; Stice, G. D.; Ewart, A. 1972: Geology,petrography, and geochemistry of the volcanicislands of Tonga. Journal of geophysical research77: 1566-1585.

Drake, D. R.; Hamilton, L.; Thomas, P. 1990: Report on abiological survey of 'Eua Island, Tonga, and aproposal for a national park. Honolulu, East-WestCenter.

Ellison, J. C. 1990: Vegetation and floristics of theTongatapu outliers. Atoll research bulletin 332:1-36.

Fosberg, F. R. 1984: Phytogeographic comparisons ofPolynesia and Melanesia. In: Radovsky, F. J.;Raven, P. H.; Sohmer, S. H. ed. Biogeography ofthe tropical Pacific. Lawrence, Association ofSystematics Collections and the Bernice P. BishopMuseum. Pp. 33^4 .

Fosberg, F. R. 1992: Vegetation of the Society Islands.Pacific science 46: 232—250.

Franklin, J.; Merlin, M. 1992: Species-environment pat-terns of forest vegetation on the uplifted reeflimestone of Atiu, Mangaia, Ma'uke and Miti'aro,Cook Islands. Journal of vegetation science 3: 3—14.

Garnock-Jones, P. J. 1978: Plant communities on Lakebaand southern Vanua Balavu, Lau Group, Fiji.Royal Society of New Zealand bulletin 17: 95—117. ' •

Gauch, H. G., Jr. 1979: ORDIFLEX-A flexible compu-ter program for four ordination techniques:WEIGHTED AVERAGES, POLAR ORDINA-TION, PRINCIPAL COMPONENTS ANALY-SIS, and RECIPROCAL AVERAGING ReleaseB. Ithaca, New York, Section of Ecology andSystematics, Cornell University.

Hill, M. O. 1979: TWINSPAN - A FORTRAN programfor arranging multivariate data in a two-way tableby classification of the individuals and attributes.Ithaca, New York, Section of Ecology and Sys-tematics, Cornell University.

Hoffmeister, J. E. 1932: Geology of'Eua, Tonga. BishopMuseum bulletin 96: 1—93.

Kirkpatrick, J. B.; Hassall, D. C. 1981: Vegetation of theSigatoka sand dunes, Fiji. New Zealand journalof botany 19: 285-297.

Kirkpatrick, J. B.; Hassall, D. C. 1985: The vegetationand flora along an altitudinal transect at MountKorobaba, Fiji. New Zealand journal of botany23: 33^46.

Merlin, M. D. 1985: Woody vegetation in the uplandregion of Rarotonga, Cook Islands. Pacific sci-ence 39: 81-99.

Merlin, M. D. 1991: Woody vegetation on the raisedcoral limestone of Mangaia, southern Cook Is-lands. Pacific science 45: 131-151.

Morat, P.; Veillon, J.-M. 1985: Contribution a laconnaissance de la vegetation et de la flore deWallis et Futuna. Adansonia 3: 259-329.

Mueller-Dombois, D.; Ellenberg, H. 1974: Aims and meth-ods of vegetation ecology. New York, John Wiley.

Orbell, G. E.; Rijkse, W. C; Laffan, M. D.; Blakemore,L. C. 1985: Soils of part Vava'u Group, Kingdomof Tonga. New Zealand soil survey report 66: 1—48.

Palmer, M. W. 1988: The vegetation and anthropogenicdisturbance of Toloa Forest, Tongatapu Island,South Pacific. Micronesica 21: 279-281.

Parham, B. E. V. 1971: The vegetation of the TokelauIslands with special reference to the plants ofNukunonu atoll. New Zealand journal of botany9: 576-609.

Schmid, P. M. 1975: La flore et la vegetation de la partiemeridionale de l'Archipel des Nouvelles Hebrides.Philosophical transactions of the Royal Societyof London, series B 272: 329^-342.

Smith, A. C. 1979,1981,1985,1988,1991: Flora vitiensisnova: a new flora of Fiji. Vols 1—5. Lawai, PacificTropical Botanical Garden.

Stoddart, D. R. 1975: Sand cays of Tongatapu. Atollresearch bulletin 181: 1—15.

Stoddart, D. R. 1992: Biogeography of the tropical Pa-cific. Pacific science 46: 276-293.

Straatmans, W. 1964: Dynamics of some Pacific islandforest communities in relation to the survival ofthe endemic flora. Micronesica 1: 113—122.

Sykes, W. R. 1978: The pteridophytes of'Eua, southernTonga. Royal Society of New Zealand bulletin 17:119-152.

Sykes, W. R. 1981: The vegetation of Late, Tonga.Allertonia 2: 323-353.

Thaman, R. R. 1992: Vegetation of Nauru and the Gilbertislands: case studies of poverty, degradation, dis-turbance, and displacement. Pacific science 46:128-158.

Thompson, C. S. 1986: The climate and weather of Tonga.New Zealand Meteorological Service miscellane-ous publication 188. Wellington.

Uhe, G. 1974: The composition of the plant communitiesinhabiting the recent volcanic ejecta of Niuafo'ou,Tonga. Tropical ecology 15: 126—139.

Wagner, W. L.; Herbst, D. R.; Sohmer, S. H. 1990:Manual of the flowering plants of Hawaii. Hono-lulu, Bernice P. Bishop Museum. Bishop Mu-seum special publication 83.

Whistler, W. A. 1980: The vegetation of Eastern Samoa.Allertonia 2: 45-190.

Whistler, W. A. 1983: Vegetation and flora of the AleipataIslands, Western Samoa. Pacific science 3 7: 227—249.


Whistler, W. A. 1991: The ethnobotany of Tonga: theplants, their Tongan names, and their uses. BishopMuseum bulletin in botany 2: 1—155.

Whistler, W. A. 1992: Vegetation of Samoa and Tonga.Pacific science 46: 159-178.

Wilde, R. H.; Hewitt, A. E. 1983: Soils of 'Eua Island,Kingdom of Tonga. New Zealand soil survey re-port 68: 1-42.

Woodroffe, C. D. 1983: The impact of cyclone Isaac onthe coast of Tonga. Pacific science 37: 181—210.

Woodroffe, C. D. 1986: Vascular plant species-area rela-tionships on Nui atoll, Tuvalu, Central Pacific: areassessment of the small island effect. Austral-ian journal of ecology 11: 21—31.

Woodroffe, C. D. 1991. Vegetation of Tuvalu. SouthPacific journal of natural science 11: 82—128.

Yuncker, T. G. 1959: Plants of Tonga. Bishop Museumbulletin 220: 1-283.

APPENDIX I

List of vascular plants recorded in thevegetation samplesSince there is no recent treatment of the spermatophyteflora of Tonga, nomenclature follows several sources.Smith (1979, 1981, 1985, 1988, 1991) treats nearly all ofthe spermatophyte species. For species not treated bySmith, the most recent treatment from among Yuncker(1959), Wagner et al. (1990), or Whistler (1991) isfollowed. Nomenclature for pteridophytes follows Sykes(1978). Tongan names are from Yuncker (1959), Sykes(1978), Whistler (1991), and the present study. Voucherspecimens are deposited in the personal collection of A.Whistler at the University of Hawai'i (UHAW).Key: E = endemic, I = indigenous, P = Polynesianintroduction, A = post-European introduction.

PTERIDOPHYTESAdiantaceaePteris comans, IPteris ensiformis, IPteris tripartita, IAspidiaceaeArachnoides aristata, hulufe leisi, ITectaria dissecta, ITectaria latifolia, IAspleniaceaeAsplenium australasicum, hakato, IAsplenium marattioides, IAsplenium polyodon, ILoxoscaphe gibberosum, hulufe leisi, IAthyriaceaeDiplazium harpeodes, IBlechnaceaeBlechnum orientale, ICyatheaceaeSphaeropteris lunulata, ponga, IDavalliaceaeDavallia solida, kulutuma, INephrolepis hirsutula, hulufe, IDennstaedtiaceaeMicrolepia speluncae, IGleicheniaceaeDicranopteris linearis, kahiva'e, I

HymenophyllaceaeTrichomanes humile, ITrichomanes saxifragoides, ILindsaeaceaeSphenomeris chinensis, ILycopodiaceaeLycopodium cernuum, hiku 'i pusi, IMarattiaceaeAngiopteris evecta, hulufe vai, IPolypodiaceaeDrynaria rigidula, IPhymatosorus grossus, IPyrrosia adnascens, IPsilotaceaePsilotum nudum, ISchizaeaceaeSchizaea dichotoma, masalu ngaue, IThelypteridaceaeChristella parasitica, ISphaerostephanos decadens, ISphaerostephanos invisus, ISphaerostephanos unitus, IVittariaceaeAntrophyum plantagineum, IGYMNOSPERMSCycadaceaeCycas rumphii, longolongo, IPodocarpaceaePodocarpus palliduSy uhiuhi, EDICOTYLEDONSAcanthaceaeGraptophyllum insularum, IAizoaceaeSesuvium portulacastrum, IAmaranthaceaeAchyranthes aspera, tamatama, I or PDeeringia amaranthoides, IAnacardiaceaePleiogynium timoriense, tangato, IRhus taitensis, tavahi, ISemecarpus vitiensis, olahi, IApiaceaeCentella asiatica, tono, A


ApocynaceaeAlyxia bracteolosa, kulu, IAlyxia stellata, maile, ICerbera odollam, toto, IErvatamia obtusiuscula, te'ete'emanu, IMelodinus vitiensis, tuamea, INeisosperma oppositifolium, fao, IAraliaceaeMeryta macrophylla, kulukulu, 1Polyscias multijuga, tanetane vao, IAsclepiadaceaeHoya austra/is, laumatolu, IHoy a pottsii, ITylophora samoensis, IAsteraceaeAgeratum conyzoides, ABidenspilosa, fisi 'uli, AConyza bonariensis, AElephantopus mollis, AEmilia sonchifolia, ASonchus oleraceus, ASynedrella nodiflora, pakaka, AVernonia cinerea, fisi puna, AWollastonia biflora, ate, IBarringtoniaceaeBarringtonia asiatica, futu, IBoraginaceaeTournefortia argentea, touhuni, ICordia aspera, tou, ICordia subcordata, pua taukanave, IBurseraceaeCanarium harveyi, 'ai, ICaesalpiniaceaeManiltoa grandiflora, tautau 'a manu, pekepeka, ICampanulaceaeWahlenbergia marginata, ICaricaceaeCarica papaya, lesi, ACassythaceaeCassytha filiformis, fatai, ICasuarinaceaeCasuarina equisetifolia, toa, ICelastraceaeMaytenus vitiensis, IClusiaceaeCalophyllwn inophyllum, feta'u, ICalophyllum neo-ebudicum, tamanu, IGarcinia myrtifolia, feto'umaka, ICombretaceaeLumnitzera littorea, ITerminalia catappa, telie, ITerminalia litoralis, telie 'a manu, IConnaraceaeConnarus sp. nov., vavatu, ERourea minor, va'a 'uli, IConvolvulaceaeIpomoea indica, fue 'ae puaka, IIpomoea macrantha, fue hina, IIpomoea pes-caprae, fue kula, IMerremia peltata, fue mea, IOperculina ventricosa, fue hina, A

Stictocardia tiliifolia, ADichapetalaceaeDichapetalum vitiense, kili, IEbenaceaeDiospyros elliptica, kanume, IDiospyros major, mapa, IDiospyros samoensis, tutuna, kokau 'uli, IElaeocarpaceaeElaeocarpus graeffei, ma'ama'alava, IElaeocarpus sp. nov., EElaeocarpus tonganus, ma'ama'alava, IEuphorbiaceaeAleurites moluccana, tuitui, PBischofia javanica, koka, IChamaesyce atoto, IChamaesyce hirta, ACroton microtiglium, IDrypetes vitiensis, IExcoecaria agallocha, feta'anu, IGlochidion ramiflorum, malolo, IMacaranga harveyana, loupata, IOmalanthus nutans, fonua mamala, IPhyllanthus amicorum, EFlacourtiaceaeHomalium whitmeeanum, IXylosma simulans, filimoto, IGesneriaceaeCyrtandra samoensis, IGoodeniaceaeScaevola sericea, ngahu, IHernandiaceaeHernandia moerenhoutiana, pipi tui, IHernandia nymphaeifolia, fotulona, IHippocrataceaeSaiacia pachycarpa, IIcacinaceaeCitronella samoensis, olavai, ILauraceaeCryptocarya hornei, motou, ICryptocarya turbinata, kakala 'uli, motou, ILitsea mellifera, mamea, ILoganiaceaeFagraea berteroana, pua, IGeniostoma rupestre, te'epilo 'a maui, ILoranthaceaeDecaisnina forsteriana, topu'uno, kainikavea, ILythraceaePemphis acidula, ngingie, IMalvaceaeAbelmoschus moschatus, PHibiscus tiliaceus, fau, ISida rhombifolia, te'ehoosi, PThespesia populnea, milo, IMeliaceaeAglaia heterotricha, langakali vao, EDysoxylumforsteri, mo'ota hina, IDysoxylum tongense, mo'ota mea, mo'ota kula, EVavaea amicorum, ahi vao, IMelastomataceaeMelastoma denticulatum, IMemecylon vitiense, malamala 'a toa, I


MenispermaceaePachygone vitiensis, IMimosaceaeAcacia simplex, tatangia, IAdenanthera pavonina, AEntada phaseoloides, sipi, IMimosa pudica, mateloi, ASchleinitzia insularum, feifai, IMonimiaceaeHedycarya dorstenioides, IMoraceaeFicus obliqua, 'ovava, IFicusprolixa, 'ovava, IFicus scahra, masi 'ata, IFicus tinctoria, masi 'ata, IMalaisia scandens, hiehieapo, IStreblus anthropophagorum, IMyristicaceaeMyristica hypargyraea, kotone, IMyrsinaceaeDiscocalyx listeri, EEmbelia vaupelii, IMaesa tongensis, IMyrtaceaeDecaspermum fruticosum, nukonuka, IPsidium guajava, kuava, ASyzygium hrackenridgei, fekika vao, ISyzygium dealatum, fekika vao, ISyzygium quadrangulatum, 1Syzygium richii, heavula, INyctaginaceaePisonia grandis, puko, 1Pisonia umbellifera, IOlacaceaeAnacolosa lutea, IOleaceaeChionanthus vitiensis, 'afa, IJasminum didymum, tutu 'uli, IJasminum simplicifolium, tutu 'uli, IOnagraceaeLudwigia octovalvis, AOxalidaceaeOxalis corniculata, kihikihi, PPapilionaceaeCanavalia cathartica, ICanavalia sericea, fue veli, IDesmodium triflorum, AInocarpus fagifer, ifi, I or PMucuna gigantea, valai, IPueraria lobata, aka, ASophora tomentosa, lata, IStrongylodon sp. nov., matafu'i, IVigna marina, lautolu tahi, IPassifloraceaePassiflora maliformis, vaine tonga, APassiflora subpeltata, APeperomiaceaePeperomia tutuilana, IPiperaceaeMacropiperpuberulum, kavakava'ulie, IPittosporaceae

Pittosporum arborescens, masi kona, IPittosporum yunckeri, ERhamnaceaeAlphitonia zizyphoides, toi, IColubrina asiatica, fiho'a, IRhamnella vitiensis, IRosaceaeOsteomeles anthyllidifolia, IRubiaceaeAntirhea inconspicua, IBikkia tetrandra, siale tafa, ICyclophyllum barbatum, IGeophila repens, tono, IGuettarda speciosa, puopua, IGynochtodes epiphytica, IHedyotis foetida, IIxora calcicola, ola, IMorinda citrifolia, nonu, IMorinda myrtifolia, mamange, IMussaenda raiateensis, monomono 'a hina, 1Neonauclea forsteri, afa, IPsychotria carnea, IPsychotria leiophylla, IPsydrax odorata, olamaka, ISpermacoce assurgens, 'aselemo, ATarenna sambucina, manonu, IRutaceaeMelicope retusa, IMicromelum minutum, takafalu, ISantalaceaeSantalum yasi, ahi, ISapindaceaeElattostachys falcata, ngatata, ngatata kula, IGuioa lentiscifolia, EHarpullia arborea, filiamaama, ISapindus vitiensis, ngatata hina, ISapotaceaeBurckella richii, kau, IPlanchonella garberi, kalaka, IPlanchonella grayana, kalaka, ISolanaceaeCapsicum frutescens, polo, polo fifisi, ASolanum amicorum, ISolanum mauritianum, pula, ASurianaceaeSuriana maritima, ngingie, IThymelaeaceaePhaleria glabra, IWikstroemia foetida, lala vao, ITiliaceaeGrewia crenata, fo'ui, ITriumfetta procumbens, IUlmaceaeCeltis harperi, ITrema cannabina, mangele, IUrticaceaeDendrocnide harveyi, salato, IPipturus argenteus, 'olonga, 1Procris pedunculata, IVerbenaceaeClerodendrum inerme, tutu hina, tutu tahi, I


Faradaya amicorum, fufula, ILantana camara, talatala, APremna serratifolia, volovalo, IStachytarpheta urticifolia, hiku 'i kuma, AViolaceaeMelicytus samoensis, IMONOCOTYLEDONSAgavaceaeCordyline fruticosa, I or PFurcraeafoetida, faumalila, AAraceaeAmorphophallus paeoniifolius, teve, PEpipremnum pinnatum, Alu, IArecaceaeCocos nucifera, niu, IPritchardia pacijica, piu, ICommelinaceaeRhoeo spathacea, faina kula, ACyperaceaeFimbristylis cymosa, IFimbristylis ovata, IMariscus sumatrensis, AScleria polycarpa, mahelele, IDioscoreaceaeDioscorea bulbifera, hoi, ILiliaceaeDianella aff. intermedia, lave'imoa, IOrchidaceaeCorymborkis veratrifolia, IGoodyera rubicunda, IHetaeria whitmeei, I

Liparis disepala, IMalaxis latisegmenta, IMalaxis resupinata, IPhaius tankarvilleae, IRobiquetia bertholdii, ISpathoglottisplicata, lave'i moa, Ifaeniophyllum fasciola, IPandanaceaeFreycinetia urvilleana, IPandanus tectorius, IPoaceaeBotriochloa bladhii, AChrysopogon aciculatus, matapekepeka, PCyrtococcum oxyphyllum, PDigitaria ciliaris, AImperata conferta, IIschaemum murinum, ILepturus repens, IMiscanthus floridulus, kaho tonga, IOplismenus compositus, mohuku laukofe, PPanicum decomposition, APaspalum conjugatum, vailima, APaspalum vaginatum, AStenotaphrum micranthum, IThuarea involuta, kefukefu, ISmilacaceaeSmilax vitiensis, matafu'i, ITaccaceaeTacca leontopetaloides, mahoa'a, PZingiberaceaeZingiber zerumbet, angoango, P

rain forest vegetation of 'eua island, kingdom of tongaconsists of older, raised limestone...

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