ATOLL RESEARCH BULLETIN 
NO. 332 
VEGETATION AND FLORISTICS 
OF THE TONGATAPU OUTLIERS 
BY 
JOANNA C. ELLISON 
ISSUED BY 
NATIONAL MUSEUM OF NATURAL HISTORY 
SMITHSONIAN INSTITUTION 
WASHINGTON, D.C., U.S.A. 
January 1990 
VEGETATION AND FLORISTICS 
OF THE TONGATAPU OUTLIERS 
JOANNA C. ELLISON 
Abstract 
On the 21 small islands located within the northern bays and reef systems of 
Tongatapu, Tonga, species of terrestrial flora present were identified, and vegetation 
units and gemorphological features surveyed on 12 that were previously unmapped. A 
species/ area plot of the data shows that rock islands are consistently more diverse than 
sand islands. Size of flora is also a function of frequency of human use of islands, 
which increases with area, and proximity to the mainland. Floristic composition varies 
from east to west across the group, with increasing shelter provided by the mainland 
from prevailing winds. 
Introduction 
Tongatapu is the largest of a group of islands that form the Kingdom of Tonga in 
the southwest Pacific (Latitude 21?08'S, Longitude 175'1 1W). The island has an area 
of 245 km2, with a maximum dimension of 35 km from east to west It is composed of 
raised Quaternary limestone (Taylor & Bloom 1977), with a low undulating 
topography. The cliffed south coast is fringed by a raised algal ridge (Ladd & 
Hoffmeister 1927), while the leeward north shore is fringed by mangroves and 
discontinuous barrier reefs. 
In association with this reef system 21 islands of 0.008 to 51.8 ha. (0.02 to 128 
acres) occur to the north of Tongatapu (Figure 1). They are of two geomorphological 
types: "sand cays" are back reef sand deposits consolidated by beachrock (Tufaka, 
Fafa, Pangaimotu, Manima, Oneata, Malinoa, Monuafe, Onevai, Onevao, Motutapu, 
Fukave, Nuku, Ata and Tau), whereas "motus" are of raised limestone (Toketoke, 
Atata, Polo'a, Alakipeau, Velitoa Hihifo, Velitoa Hahake and Mokotu'u). The larger 
islands of the former type may have a raised limestone core around which sand and reef 
breccia have accumulated. Islands are mentioned in east-west order throughout this 
paper. 
The islands result from the late Pleistocene and Holocene sea level history of the 
area. A narrow terrace at 7 m in the southern cliffs of Tongatapu was formed during the 
last interglacial (1 35f 1 8 ka) (Taylor 1978). Since all raised limestone islands of the 
Department of Geography, Simon Fraser University, Burnaby V5A 1S6, British Columbia, Canada. 
Present address: Department of Geography, University of California at Berkeley, 
Berkeley, CA 94720, USA. 
Tongatapu outliers are of 6 to 7 m in height, they would seem to be reef remnants 
fromthis highstand. The Holocene sea level record has included a stillstand 2.2 m 
higher than present, dated between 6500 and 5800 BP (Bourrouilh & Hoang 1976, 
Taylor & Bloom 1977). This mid-Holocene highstand was of regional extent, and the 
recent fall of sea level to present levels has been shown to promote sand islet formation 
(Schofield 1977). The sand cays of the Tongatapu islets are likely composed of dead 
reef material and scoured sand deposited on reef flats as sea level fell. 
The climate of Tongatapu is tropical, with two seasonal divisions. The warmer 
wet season is from November to April, with warmest mean monthly temperature of 
26.1?C in February (Thompson 1986). Two thirds of the 1900 rnm mean annual 
rainfall falls during the wet season, which is also the cyclone season. The cooler dry 
season is from May to October, with coolest mean monthly temperature of 21.2OC in 
August, when droughts may occur periodically. 
The south-east trades show remarkable constancy of direction, winds blowing 
from the eastern quadrant for 64.8% of the time (Thompson 1986). Cyclones during 
the 
historic period show periodicity of 20 to 30 years (McLean et al. 1977, Oliver and 
Reardon 1982) with moderate to severe cyclones affecting Tongatapu 1874- 1883, 
19 12-1913, 1930, 1964 and 1982. The most severe storm damage in recent years came 
with cyclone Isaac, tracking south-west through the Tonga group in early 1982 
(Thompson 1986, Revel1 1982). This affected Tongatapu most severely on the 2nd and 
3rd of March, with winds moving from south-easterly, through easterly, then strongest 
winds from the north-east and north on the 3rd, with gusts up to 92 knots recorded. On 
Tongatapu, most low-lying northern areas were badly affected by floods from high 
seas and a heavy swell (Oliver & Reardon 1982, Woodroffe 1983). Variability in 
damage was a function of aspect, and degree of protection within the central lagoon and 
behind reefs. 
Ocean tides at Nuku'alofa are semi-diurnal with a slight diurnal inequality. The 
mean tidal range is 1.07 m, and the spring range is 1.22 m (US National Oceanic and 
Atmospheric Administration 1986). 
The terrestrial flora of Tongatapu comprises 340 vascular plants (Arthur 
Whistler, pers. comm.). The natural vegetation of inland Tongatapu has been cleared 
for Cocos plantations and intensive small-holder agriculture (Thaman 1975), except for 
a small forest near Fua'amotu airport. Mangrove forests fringe the north shore and the 
central Fanga 'Uta lagoon, and natural coastal forest fringes the rugged south coast, 
and occurs on the northern islets.The vegetation of four sand cays nearest to 
Tongatapu: Pangaimotu, Makaha'a, Manima and Oneata was mapped by Stoddart in 
1969 (Stoddart 1975). Following Cyclone Isaac in 1982, Woodroffe mapped these as 
well as Tufaka, Fafa, Monuafe and Malinoa (Woodroffe 1983). 
Tongatapu is the most populated island in the Kingdom of Tonga, with 61 000 in 
the 1976 census, most living around the capital, Nuku'alofa. The terrestrial ecosystems 
of all outlier islands have been disturbed as a result of human influence. The intensity 
of human impact can be categorised on the basis of visitor frequency or size of the 
resident population. 
1) Islands with many visitors a day include Atata, Fafa and Pangaimotu, with tourist 
resort developments; Manima and Oneata, which can be walked to easily at low tide; 
and Ata, which is a low security prison camp. 
2) Islands with several visitors a week are those with a resident family, comprising 
Onevai, Velitoa Hahake and Fukave. Motutapu, periodically used for training by the 
Tonga Defence Force (TDF) is also included, as is Velitoa Hihifo, which is used as a 
TDF store, and looked after by the family on Velitoa Hahake. 
3) Islands with several visitors a month are those used for cultivation, or popular 
stopping places on fishing or recreational boat trips. These include Polo'a, Alakipeau, 
Makaha'a and Nuku. 
4) Islands with infrequent visitors may have low intensity agricultural use, and tend to 
be smaller andfor further away from Tongatapu. These include Toketoke, Tufaka, 
Monuafe, Malinoa, Mokotu'u, Onevao and Tau. 
Examination of the combined effects of alternative geomorphological types, 
varied area, isolation and degree of human disturbance on the distribution of members 
of a relatively large pool of terrestrial plant species forms the basis for this study. 
Methods 
Islands were visited between May 1987 and January 1988, and on all except the 
larger island Atata, a total species count was made of vascular plants. Morphological 
features and vegetation units were mapped for those islands not covered by Woodroffe 
(1983), and area determined. 
It is possible to walk to Pangaimotu (approaching from the east), Manirna and 
Oneata, with sand flats between being quite dry at low tide. Polo'a and Alakipeau can 
be reached by horse, or a wet walk, along a path through seagrass from Muifonua 
Point. All other islands must be reached by boat, with a frequent tourist boat service to 
Atata, Fafa and Pangaimotu. 
Morphological features and vegetation units were mapped on Toketoke, Polo'a, 
Alakipeau, Velitoa Hihifo, Velitoa Hahake, Onevai, Onevao, Motutapu, Fukave, 
Nuku, Ata and Tau (Figures 2 to 13), these islands not being mapped previously. On 
smaller islands (Toketoke, Alakipeau, Velitoa Hihifo and Tau), this was by tape-and- 
compass, with a central line and perpendicular offsets to each coast every 25 m, and by 
pace-and-compass on larger islands, with systematic transects run inland fiom the 
coast. Maps of other islands from 1982 are given by Woodroffe (1983). 
Area was determined by laying a transparent grid over these maps, and counting 
square rnm. Island areas given in Table 7 are defined by limit of vegetation, not high 
tide mark. Future researchers should note that the area figures available from the 
Ministry of Lands and Surveys are rounded to the nearest acre, and are of variable 
accuracy. 
Physiognomic types identified in mapping were coastal trees, shrubs, herbs, 
coconut woodland and mangroves, though sections dominated by a particular species 
are identified separately. Most units were diverse, a function of the relatively large flora 
of Tongatapu. Species present were noted or collected during surveying, hence larger 
islands were less intensively covered than smaller. Suggested error margins for species 
missed on the total species figures (Table 7) are +1 on small islands and +5 on larger 
islands . 
Species names and physiognomic classifications are largely taken from Yuncker 
(1959), Smith (1979-81), and Whistler (1983), also a number of experts assisted in 
identifying species, acknowledged below. Use was also made of Yuncker's herbarium 
collection, held at the Ministry of Agriculture, Forestry and Fisheries Research Farm at 
Vaini. 
Vegetation units 
An inventory of the species of trees, shrubs, herbs, vines, grasses and sedges, 
and ferns on each island is presented in Tables 1 to 6. Island areas and species totals are 
given in Table 7. A total of 203 vascular plants were identified, inclusive of weeds and 
cultivated plants. The vegetation units shown in Figures 2 to 13 are described below. 
COASTAL TREES 
The composition of coastal tree units varied from west to east across the island 
group, with shelter provided by Tongatapu from the prevailing south-east trades 
increasing westwards. Maria Bay is sheltered behind the reef to the east of Polo'a and 
Atata (Figure I), causing western shorelines of Polo'a, Alakipeau and the southern spit 
of Atata to be dominated by Vitex, in association with Thesaesia, Cerbera and 
Hibiscus. 
Coastal thickets dominated by Hibiscus occurred on islands central to the group, 
on Pangaimotu, Makaha'a, Manima and Oneata, as shown in Woodroffe's (1983) 
maps. Beach thickets were in association with Thespesia, Hernandia and Cordia. On 
the raised limestone islands of Toketoke, Northern Atata, and parts of Alakipeau and 
Velitoa Hihifo, particularly dense Hibiscus stands occur. 
In more exposed, windward locations, Acacia, Pandanus, Tournefortia 
(=Messerschmidia), Pisonia and Phaleria, Terminalia and Leucaena become dominant. 
The maps of Toketoke, Polo'a and Alakipeau show Pandanus stands on the edges of 
east facing overhanging rock, and Table 1 in listing islands from west to east clearly 
shows increased occurrence of these species towards the east. Casuarina also showed 
greater frequency towards the east, but only on rocky outcrops. Tournefortia and 
Pandanus frequently occurred opportunistically within shrub and herb units, as shown 
in Plate 1. 
Certain islands were unusually dominated by one species in particular, showing 
that competitors were absent or poorly established. Examples were Leucaena on Tufaka 
and Monuafe, Neisos~erma on Fafa, S~zveium richii on Motutapu and Pisonia on 
Fukave and Nuku. Motutapu featured an unusually diverse and well established coastal 
forest, presumably due to conservation by TDF ownership. 
COASTAL SHRUBS 
Frequent components of the coastal shrub unit were Scaevola, Colubrina, 
Wollastonia (=Wedelia) and Jasminum didvmum on all islands, also Clerodendrum 
more commonly on western islands, and Suriana more commonly on eastern islands. 
Wollastonia was most frequent on the edges of raised limestone cliffs, and Scaevola 
opportunistic of sand areas recently colonised by vines and herbs, such as the south 
point of Malinoa. 
HERBS 
Most of the 52 herbs listed in Table 3 are weed species inadvertently introduced 
by man. Hence the islands identified as most frequently visited have floras significantly 
increased by these weeds (Pangaimotu, Manima, Oneata and Ata), while those 
uncommonly visited have very few or none (Toketoke, Tufaka, Malinoa, Mokotu'u 
and Tau). 
The weeds Rivina, Stachytaqheta and Lantana are most successfully 
established, commonly on untended cultivated areas under Cocos. Rivina forms 
extensive stands across central areas of Fukave, Stachvtarph~ being absent, as shown 
in Plate 2. 
Bidens. -, Euphorbia h h ,  and Malvastrum are also common. These 
weeds are most successful in open areas under Cocos, forming a lawn-like cover 
around buildings, such as around the resorts on Fafa and Pangaimotu, also the west of 
Velitoa Hihifo and Motutapu, and the east of Fukave and Ata. 
Goats on Motutapu and pigs on Makaha'a disrupt the herb layer by rooting and 
grazing, causing fewer herbs to be present on these islands. 
Of the native coastal herbs, Sesuvium is most common, occupying large 
expanses within the mangrove area of the centre of Onevai, also colonising offshore 
rocks and upper portions of beachrock on other islands. 
On the more extensive beaches of Malinoa and Tau in particular, areas of loose 
beach sand are colonised by the vines Canavalia, Vigna and Ipomoea pes-caprae, and 
the grass Thuarea, as shown in Plate 3. Euphorbia atoto is also a successful coloniser 
of loose sand, seeming to be a native element of the flora. 
MANGROVES 
The largest mangrove area on the Tongatapu outliers is the central area of sand 
flats on Onevai, now open to tidal influence from the south, though the chart by Aldrich 
(1888) shows this area to open to the west. Patch stands of Rhizophora stvlou are 
most extensive, though Brurmiera evmnorrhiza and Rhizophora mangle (=E, 
samoensis) also occur. Slightly higher intertidal sands are covered by Sesuvium. 
Rhizo~hora occurs on sheltered shorelines of other islands, but merely as 
isolated individuals, offshore of .the northwest point of Pangaimotu, as photographed 
by Stoddart (1975), and on beachrock to the west of Polo'a and Alakipeau. R. stvlosa 
is more common than R. mangle in these locations, showing the preference of the latter 
for more brackish waters (Chapman 1970). 
Excoecaria is a mangrove species, but occurs on most islands as individual trees 
in beach habitats. 
COCOS WOODLAND 
On most islands, Cocos woodland occurred inland, and many examples of 
planting were seen. The east of Tau was cleared and planted with Cocos in 1985, and 
Woodroffe (1983) described young Cocos palms to 7 m on Monuafe, which were 
absent in 1987. Planted lines are particularly apparent on Fafa and Pangaimotu. 
Headless stumps from the 1982 cyclone still remained on Toketoke and Tufaka. On 
Onevao and Makaha'a, Cocos occurs to the edge as these islands are badly eroding, 
with loose soil cliffs to 2 m in height on all sides. 
Cocos occurs in emergent association with coastal trees such as Caloph~llum, 
-, Barringtonia, Cerbera, and Hibiscus. Planted species such as Carica, 
Morinda and Artocarpus are also common, as well as the weed-like Psidium. More 
disturbed units under Cocos are sub-classified on the maps as "Cocos over herbs and 
low weeds", including both the lawn-like cover described above and recently cleared 
areas on Tau; "Cocos over shrubs and scrub" is a less tended version of this, and 
where the palms rise above a ground cover of tall Panicum maximum, "Cocos over 
grass" is used. 
GRASS 
Areas of open grass occurred only on raised limestone islands, of tall clumps of 
Panicum (up to two meters high) interdispersed by occasional weeds, vines and 
shrubs. Large areas occurred on Toketoke and Velitoa Hihifo, and could be resultant 
from neglect after clearance of Hibiscus thicket. 
The shooting range on Motutapu is also mapped as grass, but this is a closely 
mown open lawn. 
Fauna 
Three islands had large bird populations: the reef heron (Emetta s.sacr& on 
Toketoke, and the common noddy (Anous stolidud on Fukave and Nuku. The latter 
were in association with the large Pisonia stands. Identification was from Watling 
(1982). 
The flora of Mokotu'u is an interesting reflection on transportation of seeds by 
birds. This is a limestone outcrop to the NW of Onevai, 10 m in diameter and about 6 
m high, undercut on all sides. Drift seeds could not reach it, and though I heard 
accounts of people climbing onto it, this would be extremely rare. Hence the species 
present must result from seed dispersal by birds. 
Discussion of floristics 
A log area/ number of vascular species plot for the Tongatapu outliers is given in 
Figure 14, showing that there is an approximately linear relationship as described by 
Preston (1962) and MacArthur and Wilson (1967). The scatter of data around this trend 
can be explained by several factors. 
Sand cays and motus are distinguished on the graph, clearly showing that at all 
island sizes, raised limestone islands are more diverse than sand cays. Two factors 
seem to be of importance, degree of storm disturbance, and habitat heterogeneity. 
Woodroffe (1983) noted that raised reefal limestone coasts underwent little 
morphological change during Cyclone Isaac, while greatest changes were observed on 
sand islands. Hence, referring to MacArthur & Wilson's (1963) equilibrium model, 
where species number is a result of balanced immigration and extinction rates, the 
extinction rate resulting from storms will be higher on a sand cay than a mom of the 
same area. Protection is given by the irregular and immobile rock surface, that also 
provides a diversity of microhabitats between hollows and outcrops, as well as a 
surface area that exceeds the spatial area of the island. By comparison, sand cays are 
uniform in microclimate and micromorphology. This refinement of the MacArthur & 
Wilson (1967) species/ area model of island biogeography on the basis of habitat 
diversity was made by Sauer (1969) and Buckley (1982), the latter finding similar 
variance in diversity of flora on sand and limestone islands in the Lowendal 
archipelago, Western Australia. 
Floristics of the islands is also shown to be influenced by the degree of human 
disturbance, on four recognisable scales as described. Chaloupka & Domm (1986) 
found on 10 cays of the Southern Great Barrier Reef that percentage of alien plant 
species recorded on a cay is positively related to the frequency of human visitor traffic 
to that cay, independent of cay size. On the Tongatapu outliers, it would seem that 
resources on islands larger than 8 ha. cause them to be inhabited regardless of location, 
while all islands under 4 ha. are uninhabited, with the exception of Velitoa Hahake. In 
Figure 14, the sand cays show greatest vertical scatter of data within these area 
thresholds, some being frequently visited and therefore having larger floras with weeds 
and cultigens, while others are of a similar area and yet relatively undisturbed. 
Within this marginal range of 4 to 8 ha., degree of human influence and 
consequent species number is a function of distance from Tongatapu. Oneata is 
permanently inhabited, Motutapu intermittently inhabited, and Nuku deserted to leave 
decaying buildings. As stated earlier, habitation of Velitoa Hahake is an unusual case, 
resulting in lack of normal vegetation units and a disturbed appearance. In this context, 
MacArthur & Wilsons' (1967) proposition that isolation results in a low species 
number on islands would be true. In the more traditional application, the more distant 
islands of the group, Malinoa and Tau, occur below the best fit line in Figure 14, but 
are not significantly more depauperate in flora relative to other sand cays with a similar 
level of human visitation further south. 
Data from other island groups also show greatest range in number of species on 
islands of 4 to 8 ha., from the Belize sand cays (Stoddart & Fosberg 1982: 531) and 
Kapingamarangi Atoll (Niering 1963: 137), suggesting that within this range there is 
variable human influence. This could be due to distance from population centres as 
shown for Tongatapu, or some other factor of convenience for human use, such as 
persisting dense thicket, or swampy areas. 
Variation in floristic composition of the Tongatapu outliers that is related to 
island position has been described, all islands east of Motutapu being exposed to 
prevailing winds, while those to the west are in the lee of Tongatapu. This causes 
greater frequency of certain plants to the west or east according to their ecological 
preferences, and on a smaller scale, similar patterns are visible in comparison of west 
and east coasts of each island. 
The Tongatapu outliers data do not show a constant number of species on all 
islands of less than 1.4 ha. as identified by Wiens (1962) and Whitehead and Jones 
(1969). Rather, species number of these smaller islands is quite varied, owing to 
differences in substrate type and frequency of human visitation. However, the flora of 
small sand islands such as Tufaka and Monuafe did seem to be less well established 
than larger islands, with many species comprising the counts being just one individual 
germinated on the upper beach. 
Conclusion 
Relative to other locations where species1 area studies have been carried out, the 
Tongatapu outliers have a large local flora owing to the size of Tongatapu, causing an 
overall greater species density on all islands. This provides a useful data set for 
comment on the factors controlling floristics of the group. Raised limestone islands are 
shown to be more diverse than sand cays, reflecting habitat diversity and substrate 
stability. Floristic composition varies from east to west across the group, from 
windward to leeward conditions. A threshold of 4 to 8 ha. of uncertainty between no 
and certain anthropochory is identified, within which degree of human use and 
consequent floristic changes are a function of convenient use of the marginal island, 
with distance from the mainland being the most important controlling factor here. These 
factors cause variation within a basic trend for number of species to be related to island 
area. 
Acknowledgements 
I thank several people who kindly arranged or provided boats, or other vessels: 
Peter Cowdrey, Konrad Englberger, Neil Norris, Alan March, Peter McDonald, 
Stephane Goiran, Colonel Fetu'utolu, Sione Folau and Malcolm McDonald. 
Assistance in identifying species was given by Manu Poeliami and Siale Tuifua 
(Ministry of Agriculture, Forestry and Fisheries, Tokomololo), Art Whistler (Pacific 
Tropical Botanical Garden, Hawaii) when he visited in November, also Jim Foster 
(Tonga High School) allowed me to use his photographic collection of the plants of 
Tonga. 
I also thank Ian Hutchinson (Department of Geography, Simon Fraser 
University), for comments on an earlier draft of the manuscript. 
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Key t o  Figures 2 to 13 
--
Herbs and low weeds 
Shrubs and scrub 
Coastal trees 
Hibiscus thicket 
Cocos woodland 
Cocos over grass 
Cocos over shrubsandscrub 
Cocos over herbs and low weeds 
Grass 
Mangrove 
1 Pandanus Casuarina Pisonia 
Excoecaria 
Calophy llum 
Cerbera 
Pittosporum 
Tournefortia 
Hernandia 
Beachrock 
nn Raised limestone cliff  
0 Building 
- Fence 
--- Path 
0 10 
-
Scale : m 
mgure 2 : Toketoke 
Scale : m. 
Figure 3 : Polo'a 
Scale : m. 
Figure 4 :  Alakipeau 
0 10 20 
-
Scale: rn Egure 5 : Velitoa Hihifo 
Figure 6 : Velitoa Hahake Scale : m 
0 50 
I 
scale : m 
Figure 7 : Onevai 
0 20 40 60 
-
scale : rn 

0 20 40 
scale : m 
Figure 10 : Fukave 
Dgure 1 1 : Nuku 
0 20 
. 
Scale : m. 
0 20 40 
-
scale : rn Figure 12 : A t a  
0 10 20 
-
Scale : m. 
Qgure 1 3 : Tau 
er of s~eciesl area dot for the Tona-~u outliers 
Sand cays 
Motus 
0.001 0.01 0.1 1 10 100 
Area (ha) 
Table 1A. Distribution of tree species on the Tongatapu outliers 
0, 2 %  
.- 
3 
.+. 'f 
0, 
3 0 I=, 3 x -:.Em a s  a 
0 (d 
- x - m . p  r m ~ ~ o m g g ~ g g S $ ~  $ ~ g * m ~ p ~ g S Z ~ . e r  o = o Z ~ ~ $ m ~ c m o z z o r r  c 0 , S , : x 2 3  3 3
~ ~ a a L H L z O H ~ > > z O O z L z a ~  
Acacia simplex 
Aleurites rnoluccana 
Alphitonia zizyphoides 
Annona reticulata 
Artocarpus altilis 
Barringtonia asiatica 
Bruguiera gyrnnorrhiza 
Bischofia javanica 
Calophyllurn inophyllum 
Carica papaya 
Casuarina equisetifolia 
Canthiurn barbaturn 
Cerbera odollam 
Citrus maxima 
Cocos nucifera 
Cordia subcordata 
Cycas rurnphii 
Diospyros elliptica 
Dysoxylern forsteri 
Elattostachys falcata 
Erythrina fusca 
Eucalyptus sp. 
Euphorbia tirucalli 
Excoecaria agallocha 
Ficus obliqua 
Ficus scabra 
Ficus tinctoria 
Garcinia pseudoguttifera 
Geniostorna vitiense 
Glochidion concolor 
Grewia crenata 
Guettarda speciosa 
Heritiera littoralis 
Hernandia nyrnphaeifolia 
Hibiscus tiliaceus 
lnocarpus fagifera 
Jatropha curcas 
Leucaena insularum 
Leucaena leucocephala 
X  X X X X X X X  X X X X X X X  
X  X  X  
X  X  
X  
X X  X  X X  X  
X  X  X  X  X  X  X  
X  
X  
X X X X X X X  X X X X  X X  
X  X  X X X X X  X X  X X  X X X  
X  X X X  X  X  X X  X  X  
X X X X X X X X X  X  
X  X  X X  X  X  
X  X X X X X X X X  X X  
X  X X X X X X  
X  
X  X  X X X  
X  X  
X  
X  
X  
X  
X X X X X X X  X  
X  X  X  
X  X  X X X  
X X X  X X  
X  X  X  
X X X X X X  
X X  X X X X X X X X X  
X  
X  
X  X X X  X  
X X X X X X X X X X X  X  
X  X  X  
X  X  
X X X X X X X  
X  
X  X  
X  X X  X  
X  
X  
X  X  
X  
X X X X X X  
X  
X  X  
X  
X  X  X  X  
X  X X X  
X X  X X X X  
X X X X X X  
X  
X  X  
X X X X X X  
X  X  X  X  
Table 1B. Distribution of tree species on the Tongata~u outliers 
E 
3 
.-. ' 5  
al 3 
x a  l L . - a  a g  a a ~  =I, a 3 0 5 a a 2 . i i j p 3 $  
r : m E 2 . 5 , 0 0 0 > > , a 3  2 -  C Z . f l Y  4 ) q )  
o ~ o l a a a a c 3 0 a l ~ o c c Z ~ ~ 2 ~  
+ + a a ~ T a T o Z T > > T o o I ~ z a +  
Lumnitzera littorea 
Mangifera indica 
Morinda citrifolia 
Musa x paradisiaca 
Neisosperma oppositifolia 
Pandanus tectorius 
Persea americana 
Phaleria disperma 
Pipturus argentus v.lanosus 
Pisonia grandis 
Pittosporum arborescens 
Planchonella costata 
Plumeria acuminata 
Plumeria rubra 
Pometia pinnata 
Premna serratifolia 
Psidium guajava 
Rhizophora mangle 
Rhizophora stylosa 
Rhus taitensis 
Santalum yasi 
Spondias dulcis 
Syzygium clusiifolium 
Syzygium richii 
Tamarindus indica 
Tarenna sambucina 
Terminalia littoralis 
Thespesia populnea 
Tournefortia argentea 
Vavaea amicorum 
Vitex trifolia 
Ximenia americana 
Xylocarpus moluccensis 
Xylosma simulans 
unidentified 
X 
X X X X X 
X X X X X X X X  X X  X X X X X X  
X X X X 
X X X X X X X  X X X X X  
X X X X X X X X X X X X X  X X X X X X X  
X 
X X X  X X X X X X X X X  
X 
X X X X X X X X X X X X X  
X X X X X X X 
X X X X X  
X X 
X X X 
X X X 
X X X X X X  X 
X X X X X X X X X X X X 
X X X X 
X X X 
X X X X X 
X X 
X 
X X X X  X 
X X X 
X 
X X 
X X X X X X X X X X  
X X X X X X X  X X X  X X X X X X  
X X X X  X X X X  X X X X  X X X  
X X 
X X X X X X X X  X X  X X 
X X X X X  X 
X X X X 
X X 
1 1 1  
Table 2. Distribution of shrub s~ecies on the Tonfzata~u outliers 
Acronychia niueana 
Aglaia saltatorum 
Alyxia stellata 
Ananas comosus 
Bambusa vulgaris 
Bougainvillea glabra 
Caesalpinia bonduc 
Cestrum diurnum 
Clerodendrum inerme 
Codiaeum variegatum 
Colubrina asiatica 
Cordyline fruticosa 
Crinum asiaticum 
Derris trifolia 
Desmodium umbellatum 
Furcraea foetida 
Gardenia taitensis 
Hibiscus manihot 
Hibiscus rosa-sinensis 
lndigofera suffruticosa 
lpomoea batatas 
Jasminum didymum 
Jasminum simplicifolium 
Lantana camara 
Macropiper puberulum 
Malvaviscus arboreus 
Manihot esculenta 
Melia azedarach 
Micromelum minutum 
Pemphis acidula 
Ricinus communis 
Rosa sp. 
Saccharum sp. 
Scaevola sericea 
Sophora tomentosa 
Suriana maritima 
Triumfetta rhomboidea 
Wollastonia biflora 
Waltheria americana 
unidentified 
X  
X  
X  
X X X  
X  
X X X X X X X X X X X  
X  
X X X X X X X X X X X X  
X  X X  X  X X  
X  X X X  X  X  
X  X  X X X  
X  
X  X  X  
X  
X  
X X X  X  
X  X X X X X  X  X  
X X X X X X X X X  
X X X X X X X X  X X X  
X  X  
X X X X X X X X X X X X X  
X  X  
X  X  X  
X  
X X X X X X X X X X X X X  
X  
1 1 1  1 
X  X X X X X  
X X X X X X X  
X  
X X  X X X  
X  X  X  
X  
X X X X X  
X X X  
X X X X X  
X X  X  
X  X  
X  X  X  
X X X X  
X  X  X  X  
X  
X X X X X X X  
X 
X  X X X X X  
X X X X X X  
Table 3A. Distribution of herb s~ecies on the Tongata~u outliers a E % 
3 + " 5 
a, 
3 0 
x o m  2 -:.Em a 2  =I, a 3 
~ g , ~ + e y $ g ~ - ~ $ s $ ,  
~ Z S % Z Y  C C q)= C . - Y  q) q) 
0 3 0  ~ m m m C m o 5 ~ o c c ~ ~ 5 ~ =  k k a z L z a T O z z > > z O o z L z a ~  
Achyranthes aspera 
Ageratum conyzoides 
Alocasia macrorrhiza 
Arnaranthus viridus 
Arnylotheca isularum 
Apium leptophyllum 
Asclepias curassavica 
Asparagus sp. 
Bidens pilosa 
Capsicum frutescens 
Cassia occidentalis 
Cassia oppositifolia 
Cassia tora 
Catharanthus roseus 
Centella asiatica 
Coleus arnboinicus 
Colocasia esculenta 
Cornrnelina diffusa 
Crassocephalurn crepidioides 
Desrnodiurn incanurn 
Desmodiurn heterocarpon 
Elephantopus rnollis 
Ernilia sonchifolia 
Erigeron sumatrensis 
Euphorbia atoto 
Euphorbia cyathophora 
Euphorbia hirta 
Euphorbia prostrata 
Helianthus sp. 
Hedyotis foetida 
Lepidium virginicurn 
Ludwigia octovalvis 
Malvastrum coromandelianurn 
Mimosa pudica 
Oxalis corniculata 
Phaseolus lathyroides 
Phyllanthus prob. annuus 
Plantago lanceolata 
X  
X  
X  
X  
X  X  
X X X X  X  X  
X  X  
X  X  X  
X  X X X X X X  X  X X  
X  X  
X  X  
X  
X  X  
X  X  X  X X X  X X  X X  
X  X  X  
X  
X  X  X  
X  X  
X  X  
X  X X X  X  X  X  X  X  
X  
X  
X  X X X X X  X  X  X X  X X  
X  X X  X  X  
X X X X X X X X X X X X  X X  X X X X  
X  X  
X  X X X X X  X  X  X X X X X  
X  X X X X X  
X  
X  X  
X  X  X  X  X  X  
X  
X  X  X X  X X X X  X  
X  
X  X  
X  
X  
X  X X X  
Table 3B. Distribution of herb s~ecies on the Tongata~u outliers 
a E % 
3 
' c. 'I 
a 3 0 = 1 3  3 
Y a n B S - E a m a s a  m > . a s z s  E z ? d ~  r a E -  p - , z . z  p - ~  Bd :.se.2 b $ 2 9 3  a  3 
0 3 ~ - ~ a ~ a C a O ~ ~ O C C o 3 3 ~ a  
+ + L U L Z L T O I Z > > T O O Z L Z ~ +  
Portulaca oleracea 
Rivina humilis 
Sesuvium portulacastrum 
Sida rhombifolia 
Solanum nigrum 
Sonchus oleraceus 
Spermacoce assurgens 
Stachytarpheta urticaefolia 
Synedrella nodiflora 
Tacca leontopetaloides 
Taxacum officinale 
Triumfetta procumbens 
Youngia lyrata 
unidentified 
X  X  X  X  X  X X X  
X X X X X X X X  X X X X X X X X X  
X  X X  X  X X X  X X  X  
X  X  X  X  X  X  
X  X  X  
X  X  X  
X X X X X  X X  X X  
X  X  X  X  X  X  X  X  X  X  X  
X  X  X  X  X  X  
X  
X  X  X  X  X  X  X  
X  X  X  X  
X  X  X  
1 
Table 4. Distribution of vine s~ecies on the Tongatapu outliers 
E < 
3 
4- r r  
Q, 3 0 = ? =  3 
Y $ -z.E m m - 3 . - o m m  Q 
E ! Z ~ =  ~ g ~ ~ e y ~ ~ i ; g ~ ~ g =  
~ Z ~ E Z ,  Q , ~ ~ - X X  a =  
o ~ O ~ ~ ~ ~ ~ C ~ o Q , ~ o C K o ~ ~ ~ ~  
+ + L ~ L H L I O I I > > Z O O I L ~ ~ +  
Abrus precatorius 
Canavalia cathartica 
Canavalia rosea 
Canavalia sericea 
Cassytha filiformis 
Cucurbita pep0 
Dioscorea alata 
Dioscorea bulbifera 
Hoya australis 
lpomoea littoralis 
lpomoea macrantha 
lpomoea pes-caprae 
Merremia peltata 
Mucuna gigantea 
Passiflora edulis 
Passiflora foetida 
Passiflora quadrangularis 
Passiflora triloba 
Phaseolus aureus 
Pueraria lobata 
Vanilla planifolia 
Vigna marina 
unidentified 
X  X  X  X  X  X  
X  X  X  
X X X X X X X  X X X X  X X  X  
X X X X X X X X  X X X X  X X  X  X X  
X  X X X X X  X X  X  X X  X X  
X  X  
X  X  
X  X  
X  X X  X  
X  X  X  X  
X  X  X  X  X X  
X  X  X X X X X X  X X X X X  X  
X 
X  X  X  X  
X X X  X  X  
X X X X X X X  X X X  X  X  X  
X  X  
X  X  X  
X  X  
X  X  
X  
X X  X X  X  X X  X X X X  
1 
Table 5. Distribution of mass and sedge s~ecies on the Tongatapu outliers 
Brachiara mutica 
Cenchrus echinatus 
Cyperus rotundus 
Digitaria horizontalis 
Digitaria setigera 
Eleusine indica 
Eragrostis amabilis 
Fimbristylis cymosa 
lschaemum mirinum 
Kyllinga brevifolia 
Lepturus repens 
Mariscus javanicus 
Panicum maximum 
Paspalum conjugatum 
Sporobolus virginicus 
Thuarea involuta 
unidentified 
X  X  X  
X  
X  
X  X  
X  X  
X  
X  X  X  X  
X  X  X X  X  X X  X X X  
X  X  X  
X  X  X X  X X  X  
X  X  X  X  X  X  X  
X X X X X X X X X X X X X  X  X  
X  X  X  X  
X  X X X X  X  X  X X X X X X X  
X  X X X X X X X X  X X  X X X X  
1 
Table 6. Distribution of fern s~ecies on the Tonrrata~u outliers 
Asplenium nidus X X X 
Polypodium scolopendria X X X X X X X X X  X X  X X X 
Table 7. Numbers of species of vascular plants on the Tongata~u outliers 
ISLAND Area (ha.) No. species 
Toketoke 
Tufaka 
Polo'a 
Alakipeau 
Fafa 
Makaha'a 
Pangaimotu 
Manima 
Oneata 
Malinoa 
Monuafe 
Velitoa Hihifo 
Velitoa Hahake 
Mokotu'u 
Onevai 
Onevao 
Motutapu 
Fukave 
Nuku 
Ata 
Tau 
Trees Shrubs Herbs Vines Grasses 
/sedges 
3 1 
4 5 
1 0  8 
5 5 
1 0  5 
8 5 
1 2  8 
6 6 
6 5 
3 5 
6 3 
6 4 
5 6 
0  0  
9 4 
5 6 
5 3 
1 0  6 
3 6 
9 1 0  
6 2  
Ferns 
Plate 1: Pandanus out~~osts. east shore of Ata. 
Plate 2: Rivina under Cocos woodland. Fukave. 
Plate 3: Canavalia and Thuarea colonising: loose sand. west shore of Ata.