Pacific Science (1992), vol. 46, no. 2: 128-158 © 1992 by University of Hawaii Press. All rights reserved

Vegetation of Nauru and the Gilbert Islands: Case Studies of Poverty, Degradation, Disturbance, and Displacement!

RANDOLPH R. THAMAN 2

ABSTRACT: The indigenous floras of the raised phosphatic limestone island of Nauru and the atolls of the Gilbert Islands are among the poorest on earth. Long settlement, widespread destruction during World War II, monocultural expansion ofcoconut palms, and more than 75 yr ofopen-cast phosphate mining in the case of Nauru have led to serious vegetation degradation, disturbance, and displacement. The floras of Nauru and the Gilbert Islands consist of approximately 487 and 306 species, respectively, of which only 55 and 83 are possibly indigenous, but none of which are endemic. The balance is composed ofornamentals, weedy exotics, food plants, and a limited number ofother useful cultigens. Although greatly outnumbered by exotics, indigenous species still dominate some of the most disturbed habitats, as well as constituting the most culturally utilitarian and ecologically important species. Because of the unique adaptability ofindigenous Pacific island plants to the harsh conditions ofcoastal and small-island environments, and their cultural and ecological utility, it is argued that the protection and enhancement ofthe indigenous floras are crucial to the ecological integrity and cultural survival of small-island Pacific societies.

THIS PAPER FOCUSES ON the vegetation of Previous Studies Nauru and the Gilbert Islands (part of the Although collections were made on Nauru Republic of Kiribati), with specific emphases by Burgess in 1935; Fosberg in 1980; Scully in on: (I) the nature of the existing floras and 1980; Thaman, Hassall, and Manner in 1980 vegetation associations; (2) the importance of and 1981; Thaman and Manner in 1987; and indigenous species relative to exotics in the Swarbrick in 1988, little has been published. vegetation associations; (3) the role ofhuman The only substantial publications are those of disturbance and dispersal, particularly post­ Manner, Thaman, and Hassall (1984, 1985); European-contact disturbance and dispersal Thaman, Manner, and Hassall (1985); and in the impoverishment, modification, degra­ Fosberg, Sachet, and Oliver (1979, 1982, dation, displacement, and enrichment of the 1987). These publications include most of the indigenous floras and vegetation; and (4) an species cited and specimens examined before analysis of the cultural and ecological impor­ 1980. tance of the indigenous floras in the context The flora and vegetation of the Gilbert of modern small-island development. Islands and the Republic ofKiribati are better documented. The most detailed publications include those of Luomala (1953); Catala

I Paper prepared for the Vegetation Ecology of the (1957); Moul (1957); Small (1972); Overy, Pacific Islands Symposium SI-6-08 in honor ofDr. F. R. Polunin, and Wimblett (1982); Thaman Fosberg, International Congress of Ecology V, Yoko­ (I987a); and Fosberg and Sachet (1987). Oth­ hama, Japan, 27 August 1990. Manuscript accepted for er studies include those of Fosberg (1952), publication 2 May 1991. Christophersen (1927), and Wester (1985), 2 Department of Geography, School of Social and Economic Development, The University of the South which provide information on the plants ofthe Pacific. P.O. Box 1168, Suva, Fiji. atolls outside the main Gilberts group. Other 128 Vegetation of Nauru and the Gilbert Islands-THAMAN 129 accounts are those on Abemama (Watters and Islands proper (formerly part of the British Banibati 1977), Butaritari (Sewell 1979), Gilbert and Ellice Islands Colony, known North Tabiteuea (Geddes 1975), and Tamana locally as Tungaru), the Phoenix Islands, and (Lawrence 1977). Thaman's studies (1987b, the Northern and Southern Line Islands, plus 1988a, 1990a) provide information on species the isolated island of Banaba. These islands found in houseyard gardens and agricultural have a combined land area ofonly 811 km2 in 2 areas. Useful general studies of atoll and an ocean area of some 13 million km . small-island vegetation include Merrill (1945), The main Gilbert Islands, the focus of this Fosberg (1960, 1965), Wiens (1962), Alkire paper, consist of 16 small atolls or reef islets (1974), Soucie (1983), Guerin (1982), and extending 640 km from north to south. They Manner (1987). are 700 km east of Nauru, 400 km east of Banaba, and about 250 km north and south, respectively, of the atoll nations of Tuvalu Current Study (formerly the Ellice Islands) and the Republic The current study is based on an in-depth of the Marshall Islands. Both Nauru and the analysis of the above sources; 5 weeks of Gilbert Islands are at considerable distances fieldwork during three visits on Nauru in from the Philippines, Indo-Malaya, Austra­ 1980, 1981, and 1987; a to-day field study in lia, and Melanesia, the source regions or the Gilbert Islands with I-Kiribati informants centers of dispersal of most Pacific island on Abemama and North and South Tarawa floras (Merrill 1945, Manner 1987).. 2 in Ausust 1984; and a 2-week reconnaissance Nauru, with an area of only 22 km , con­ survey on Tarawa in 1989. During these sists of a narrow coastal plain, ranging from studies the Latin and Kiribati names of all 50 to 300 m wide, encircling a limestone plant species found in urban and rural areas escarpment rising some 30 m to· the central were recorded, and the lists were cross~ plateau (Figure 1). The escarpment ranges in checked with names listed from previous gradient from vertical cliffs to gradually slop­ studies. Two collections of herbarium speci­ ing areas of colluvial soil il}terspersed with mens held by the Agricultural Division and limestone outcrops and pinnacles. The pla­ the University of the South Pacific (USP) teau, with a maximum .elevation of 70 m, Atoll Research and Development Unit consists ofa matrix oflirilestone pinnacles and (ARDU) on Tarawa were also studied in outcrops, between which lie extensive deposits 1984. of soil and high-grade tricalcic phosphate rock (Tyrer 1963, Viviani 1970). Buada La­ goon, about 12 ha in size, located in the low-lying southwest central portion of the NAURU AND THE GILBERT ISLANDS island, is a landlocked brackish lake, with an associated fertile depression. The Islands The Gilbert Islands (Figure 2) are for the The Republic of Nauru, a single uplifted most part atolls with central lagoons and limestone island, west of the Gilbert Islands, encircling islets of various sizes and shapes. is located 142 km south of the equator at Kuria, Tamana, and Arorae are slightly raised 166 0 56' E, some 2000 km east-northeast of limestone islands without lagoons. The total 2 Papua New Guinea, 4450 km south-southeast land area is estimated at 294 km , and the of the Philippines, and an equal distance islands range in size from Tamana and Makin 2 southwest of Hawaii. The nearest island is (5.2 and 7.2 km , respectively) to Maiana, Banaba (Ocean Island), 300 km due east. Abaiang, and Tabiteuea (28.1, 28.5, and 49 0 2 The Republic of Kiribati, between 4 43' N km , respectively). Tarawa, where the capi­ 0 0 and 1l 0 25' Sand 169 32' and 150 14' W tal is located, is the most populous island, (Douglas and Douglas 1989), consists of 33 with 21,393 people in 1985. It has islets with islands in three main groups, the Gilbert an estimated area of 19.9 km2 and extends 130 PACIFIC SCIENCE, Volume 46, April 1992

NAURU

\, R••I eml Edg. Sealed Rood Unseal.d Road

Government Office. -_...... :

o, Kilometre.

FIGURE I. Map of Nauru. over 64 km from north to south (Catala deposited during storms. This rampart is com­ 1957). monly the highest point on the islet, no more On a typical islet there is usually an uplifted than 4 m above mean sea level. Lagoonward fringing reef in the wave zone of the ocean of the rampart, and extending to the lagoon side. The reef may be covered by a sandy itself, is an area of windblown sand. Toward beach, which becomes a raised rampart or the lagoon shore, increasingly fine deposits shingle ridge ofcoral boulders and fragments are of lagoonal origin. Limestone outcrops Vegetation of Nauru and the Gilbert Islands-THAMAN 131

173°E THE GILBERT ISLANDS :;:;<~.&} Makin Butaritari

:~" Marakei Abaia~f::): :~ " ~~i", Tarawa ::. 11.., , .0' :'~.~'~" .{):' Maiana

0°- -- -

:i';'. Nonouti :'~ '~...... "

·····:0.°: Beru :~. ,~ Tabiteuea ·0 " ...•. ..\" ...... ~ ..~ '" Nikunau ~~.'.~ ·iJ t~~·, :o.l.. Onotoa

Kilometres Arorae I i I o 50 100 Tamana ':~.,

FIGURE 2, Map of the Gilbert Islands, 132 PACIFIC SCIENCE, Volume 46, April 1992

with little or no soil and low-lying swampy production of even coconut palms (Catala areas are often found as well. 1957).

Water Resources Soils Apart from Buada Lagoon on Nauru, there The coastal soils of Nauru and the soils of are no significant surface freshwater resources the Gilbert Islands are among the poorest in on Nauru or the Gilbert Islands. The only the world. They are shallow, alkaline, coarse­ permanent freshwater resource is ground­ textured, and have carbonatic mineralogy. water in the form of a lens of often slightly Both are composed of a variable layer of brackish fresh water, hydrostatically floating organic matter, coral sand, and fragments, on higher density salt water beneath it. The which overlays a limestone platform: On Nau­ height of the freshwater lens above sea level ru coastal soils are generally drier, only about and the level of salinity vary in relation to the 25 cm deep, and contain more coral gravel elevation, geology, texture, shape, and width than sand in the lower horizons. The Gilbert ofislets, and with the amount ofwater use and Islands soils tend to be deeper, from 25 cm to rainfall. Replenishment or recharge ofthe lens I m or more deep, and are wetter, with some is dependent on rainfall. Pools are sometimes accumulation ofclays, and with H 2 S near the found, during excessively wet periods, in areas center ofislets near the water table. Potassium where the lens is close to the surface, especially levels are often extremely low, and pH values during high tides. The location and degree of ofup to 8.2 to 8.9 and high CaC03 1evels make development of the groundwater resource in­ scarce trace elements, particularly iron (Fe), fluences the nature of the vegetation, as well manganese (Mn), copper (Cu), and zinc (Zn), as the location of village wells and cultiva­ unavailable to plants. Fertility is, therefore, tion pits (Catala 1957, Small 1972, Lawrence dependent on organic matter for the concen­ 1977). tration and recycling of plant nutrients, lowering soil pH, and for soil water retention in the excessively well-drained soils. Although Climate levels of organic matter can be relatively high Climatically, both Nauru and the Gilbert in undisturbed soils under natural vegetation, Islands are located in the dry belt of the they can decrease dramatically as a result of equatorial oceanic climate zone, with mean clearance by fire or replacement by coconuts daily temperatures ranging from 26 to 32°C. and other introduced plants (Catala 1957, Annual rainfall is extremely variable in both Small 1972, Morrison 1987; also R. J. Mor­ groups. Nauru averages 1500 mm per year rison, 1987, comments on the soils ofNauru, with a range of 300 to 4572 mm. In the Commission ofInquiry into Rehabilitation of Gilberts, rainfall varies both annually and Worked-out Phosphate Lands in Nauru, In­ between islands, with annual averages of stitute of Natural Resources, Univ. ofthe So. about 1000 mm for the drier islands such as Pac., Suva, unpubl. ms.). Arorae and Tamana in the south, to 3000 mm The plateau soils ofNauru vary from shal­ for the wetter islands such as Butaritari in the low soils, composed primarily oforganic ma­ north, and 1550 at Tarawa. Severe prolonged terial and sand or dolomite, with little phos­ droughts, with as little as 200 mm of rain per phate, on the tops of limestone pinnacles, to year, are common, particularly in the central deep phosphatic soils and sandy phosphatic and southern Gilberts (Carter 1984). These rock, up to over 2 m deep between the pinna­ droughts, such as those that prevailed over the cles. Topsoils range from 10 to 25 or 30 cm in group from 1987 to early 1989, place severe depth, overlaying a deeper material that is stress on even the most hardy coastal strand frequently reddish yellow and between 25 and species, lead to the death ofnoncoastal exotics 75 cm deep, changing to pinkish gray at (such as breadfruit), and severely restrict the greater depth. Undisturbed plateau soils have Vegetation ofNauru and the Gilbert Islands-THAMAN 133

a high level oforganic material and are gener­ residential areas on the escarpment. The town ally fertile. center is located between the airport and Calcium dominates the exchange complex Location near the cantilevers (Figure 1), with and exchangeable magnesium is also high. most government offices near the airport. Exchangeable potassium is low, while ex­ In 1985 the population of the Republic of tractable phosphate values are generally high Kiribati was 63,883, of which 61,419 were and sulphate moderate. Levels of the trace I-Kiribati. Over one-third (21,393) lived in elements manganese, copper, cobalt, and mo­ urban Tarawa, the capital and commercial lybdenum are low, and these, plus iron and center, with the balance living in villages in zinc, are rendered unavailable to plants under rural North Tarawa and other islands. At a pH values> 6.5 (Morrison 1987, unpubl. ms.). projected growth rate of 4.3%, by 1993 the There are also scattered areas of phosphate population of the urbanized area of South soils and deposits in the Gilbert Islands. They Tarawa would increase to 34,066, a popula­ seem to have originated from guano deposits tion density of 4705 per km2 (Douglas and accumulated over long periods of time under Douglas 1989). groves of Pisonia grandis, a favored seabird rookery species (Sachet 1983). These soils are Development History often more acidic and darker than the sur­ rounding soils. The early post-European-contact histories Around Buada Lagoon and in some poorly of both Nauru and the Gilbert Islands are drained swampy areas near the base of the similar (Viviani 1970, Carter 1984). After the escarpment on Nauru, and in some low-lying first recorded European sightings ofthe islands areas on the islets of the Gilberts, there are in 1606 and 1798, respectively, the earliest sig­ poorly developed, but relatively fertile, wet nificant contacts with Europeans were be­ soils. tween 1820 and 1870. In that period, British and American whalers made regular stops for water and food, and beachcombers arrived. The People The next phase of contact was with traders, The indigenous peoples of both Nauru and including slave and labor traders (in the case the Gilbert Islands are Micronesians, who ofthe Gilberts) and missionaries in the mid- to have probably inhabited the islands for 3000 late nineteenth century. Coconut oil was the years or more. On Nauru, there is some evi­ main commodity until copra replaced it in the dence of Melanesian, and possibly Polyne­ late 1870s, although sporadic copra trade from sian, influence (Viviani 1970); in the Gilberts Nauru was not established until the 1890s. there has been long contact with Polynesia, Nauru was incorporated into Germany's particularly with Tuvalu (the Ellice Islands) to Marshall Islands Protectorate in 1888; the the south (Bellwood 1978). Gilbert Islands were made a British protector­ The estimated population ofNauru in 1983 ate in 1892. Along with Banaba and Tuvalu, was 8042, ofwhom 4964 were Nauruan, with they became part of the Gilbert and Ellice the balance composed mainly of I-Kiribati, Islands Colony in 1916. In 1919, after World Tuvaluan, Chinese, Filipino, or Solomon Is­ War I, Nauru became a League of Nations land contract workers in the phosphate indus­ mandate ofGreat Britain, Australia, and New try. There are also European, Indian, and Zealand, administered by Australia. Nauru Pacific Island expatriates working mainly for became independent in 1968 and the Republic the Nauruan Government. The Nauruans live of Kiribati was established in 1979. on the coastal strip and around Buada La­ The strategic and economic importance of goon, the phosphate workers in the Nauru both groups increased dramatically with the Phosphate Company dormitory accomoda­ discovery, at the turn of the century, of tion at Location near the phosphate loading high-grade phosphate rock on both Nauru cantilevers, and the expatriate civil servants in and Banaba. Mining of phosphate began in 134 PACIFIC SCIENCE, Volume 46, April 1992

1907 and 1906, respectively, without the ap­ the 1950s. Phosphate earnings have made proval of the indigenous inhabitants. Caro­ Nauru among the wealthiest nations in the line Islanders and Chinese contract laborers world in terms ofper-capita income, although were recruited to mine the deposits on Nauru the distribution of wealth is uneven because and Gilbert Islanders on Banaba. The de­ of the unequal land rights to phosphate de­ posits on Nauru have been mined continu­ posits. Nauru is considered totally urbanized ously since 1907, except for disruptions during and Nauruans have almost completely aban­ the two world wars. Mining ceased on Banaba doned subsistence production, except for the in 1979. The deposits on Nauru are expected harvest of coconuts and pandanus fruit for to be depleted by the turn of the century. consumption and pandanus leaves for plaited Through the late nineteenth century and ware; the acquisition of fish and other sea­ early years ofthe twentieth century the popu­ foods; and the hunting of noddy birds, a lations ofboth the Gilbert Islands and Nauru traditional pastime. Most of the limited sub­ were negatively impacted by the inroads of sistence agricultural production is in the European influence and suffered extensively hands of immigrant communities. The estab­ from introduced diseases to which they were lishment ofits own heavily subsidized interna­ not immune. The population of Nauru espe­ tional airline, Air Nauru, in 1970, and the cially declined dramatically between the mid­ extension of the runway over the reef, have nineteenth century and the first decades ofthe accelerated the processes of urbanization twentieth century: there were 1400 Nauruans and an increasing dependence on imported in 1840 and 1250 in 1910 (Viviani 1970). The products. most disruptive period for both Nauru and Since the cessation ofphosphate mining on the Gilbert Islands was, however, during Banaba in 1979, copra has remained the only World War II, when the islands were occupied significant source ofincome in rural Kiribati. by Japan, suffered continuous bombing by Exports of tuna and maricultural production Japanese and American planes, were settled of tuna baitfish and milkfish for export to by thousands of Japanese marines, Japanese, Nauru and Hawaii, and the recent production and Korean laborers, and when some 700 of the seaweed Eucheuma for export now Banabans were relocated to Nauru and indig­ surpass copra as the main sources of export enous populations ofboth Nauru and Banaba income. The subsistence economy in rural were decimated by deportation. There fol­ Kiribati remains strong, with a high depen­ lowed severe food shortages, malnutrition, dence on traditional staple food crops­ and dysentery. As argued by Viviani (1970): coconut, breadfruit, pandanus, the native fig "The Japanese had destroyed the Nauruan's (Ficus tinctoria) and giant swamp taro (Cyr­ homes, schools, and churches, placed them on tosperma chamissonis), pigs, chickens, and a semi-starvation level and destroyed much of marine foods. Although Kiribati is increas­ what was left of their old way of life. The ingly urbanized, with over one-third of all deportation of two-thirds of the Nauruans I-Kiribati now living in urban South Tarawa, and the death of nearly 500, mostly the old there remains a considerable dependency on and the young, left the society after the war subsistence production, even in urban areas. with a gap in generations and a disruption of There is, however, rapidly increasing depen­ family life. Again the Nauruan population dence on rice, flour, and other imported had fallen well below the 1,500 level which the foods, even in rural areas. Improved road Nauruans themselves regarded as a minimum networks and the construction of airfields on for survival." all of the islands of the Gilbert group and on Kiritimati (Christmas Island) in the Line Is­ lands have also accelerated the process of Contemporary Economy urbanization. Nauru's sole export continues to be phos­ Because of the environmental factors de­ phate; the sporadic export of copra ceased in scribed above-extreme isolation from major Vegetation of Nauru and the Gilbert Islands-THAMAN 135 plant source regions, small island size, ex­ nalia catappa, Ochrosia elliptica, and isolated tremely poor soils, and climatic and physio­ specimens of Barringtonia asiatica, Thespesia logical drought-the indigenous floras ofNa­ populnea, and Hernandia nymphaeaefolia. uru and the atolls of the Gilbert Islands are Shrubby species include Scaevola sericea, among the poorest and most restricted on Colubrina asiatica, Abutilon indicum, and earth. Moreover, the long settlement history, Phyllanthus societatis; herbaceous species in­ widespread destruction during World War II, clude Cyperus javanicus, Digitaria setigera, monoculturahxpansion of coconut palms as Vigna marina, Ipomoea macrantha, and the the sole cash crop, increasing urbanization ferns Polypodium scolopendria and Nephrole­ and contact with the outside world, and over pis biserrata. Caesalpinia bonduc, Sida fallax, 75 years of open-cast phosphate mining (on and Triumfetta procumbens are scarce, but Nauru and Banaba) have all played a role in were probably more abundant in the past. the serious degradation, disturbance, and dis­ In the Gilberts the seaward rampart vegeta­ placement ofthe indigenous floras and vegeta­ tion is dominated by Scaevola sericea, which tion. commonly forms an almost unbroken belt in areas away from settlements. Other dominant species include Tournefortia argentea, Pan­ VEGETATION TYPES danus tectorius, and occasionally Guettarda Coastal Strand Vegetation speciosa, which are usually found as isolated specimens or in small groups, and the ubi­ The coastal strand vegetation ofNauru and quitous coconut. Herbaceous species include the Gilbert Islands has been severely modified Lepturus repens, Fimbristylis cymosa, Trium­ as a result of: (1) thousands ofyears ofhuman fetta procumbens, Euphorbia chamissonis, and habitation and selective removal of indige­ the parasitic Cassytha filiformis, often grow­ nous species for construction, boatbuilding, ing on Scaevola. Infrequently present are the firewood, and other purposes; (2) the expan­ naturalized aboriginal introductions Tacca sion of monocultural coconut groves for ex­ leontopetaloides and Eragrostis amabilis. On port production ofcoconut oil and copra; (3) the inner borders of the rampart vegetation, the expansion ofcoastal settlements, which in particularly on bare limestone or conglomer­ Nauru and in urban South Tarawa occupy ate areas, almost pure stands of Pemphis most ofthe coastline; and, (4) the widespread acidula are found, and Sida fallax, Portulaca practice ofallowing pigs to forage freely along australis, P. lutea, Boerhavia repens, and B. beach flats (Viviani 1970). tetrandra occupy more open areas. Tree spe­ The dominant species in the outer coastal cies, such as Barringtonia asiatica, Cor­ zone in Nauru include the herbaceous species dia subcordata, Hernandia nymphaeaefolia, Lepturus repens, Cyperus javanicus, Ipomoea Premna serratifolia, Pisonia grandis, and Ter­ pes-caprae, and Vigna marina; the woody minalia samoensis, and the shrubs Suriana species Scaevola sericea, Tournefortia argen­ maritima and Sophora tomentosa, which are tea, and Morinda citrifolia, plus the aboriginal either localized or only rarely encountered, introduction, Cocus nucifera. Species com­ were probably much more abundant in the mon on rocky limestone sections of the coast past before their widespread removal (Fos­ include the same species plus Polypodium berg 1952, Catala 1957, Moul 1957, Geddes scolopendria, Capparis cordifolia, Cleroden­ 1975). drum inerme, Terminalia catappa, and Calo­ Along the much more highly disturbed phyllum inophyllum. Species present on non­ lagoon shores, vegetation includes Tourne­ rocky, somewhat disturbed inland coastal sites fortia argentea, Scaevola sericea, and Guet­ between the strand and the base ofthe escarp­ tarda speciosa, bordered by coconuts, and the ment include Hibiscus tiliaceus, Cocus nucifera, grass Lepturus repens and the sedge Fimbri­ Premna serratifolia, Calophyllum inophyllum, stylis cymosa iil wetter sites. Pemphis acidula is Pandanus tectorius, Morinda citrifolia, Termi- also common inland from mangroves (Catala 136 PACIFIC SCIENCE, Volume 46, April 1992

1957, Moul 1957), and Clerodendrum inerme lagoonless arid islands of the south, such as is present on some islands (Luomala 1953). Tamana and Arorae (Lawrence 1977). The swampy areas surrounding Buada La­ Mangroves and Coastal Marsh Vegetation goon and near the base of the escarpment on Nauru are dominated by Cyperus javanicus Shallow-water habitats with muddy bot­ and C. compressus, with one specimen of toms and protected from strong wave action Ludwigia octovalvis collected from a coastal are almost nonexistent on Nauru, but are depression. In the Gilberts, where there are relatively widespread on the lagoon sides of more extensive areas of inland swamps and islets in the Gilberts. Although reportedly man-made swampy depressions and Cyrto­ present in the past around Buada Lagoon, sperma pits, the dominant species are C. Nauru's single mangrove species, Bruguiera javanicus, C. laevigatus, and C. compressus, gymnorhiza, is now restricted to a system of with L. octovalvis also very common in aban­ landlocked brackish ponds or small lagoons doned Cyrtosperma pits. near the base of the escarpment in Meneng, Anabar, and Anetan Districts; the largest Relict Stands ofInland Forest concentration is found around Araro Lake in Anetan. Fosberg (ca. 1972) also reported the There are two distinct types ofrelict stands occurrence of B. gymnorhiza in landlocked ofprimary inland forest on Nauru: (1) plateau ponds, sinkholes, and small inland swamps in forest, which probably covered up to 90% of Palau. Other species commonly associated the island before the onset ofphosphate min­ with mangroves and present in Nauru include ing, and (2) escarpment forest, including for­ Derris trifolis, encountered on limestone out­ est on unmined limestone outcrops or pinna­ crops, and Vitex negundo, which is present in cles on the plateau. The former, four-fifths of depressions on the coastal strip in Menen which was removed during phosphate mining, District. is dominated almost entirely by 16-m-tall In the Gilberts, monospecific Rhizophora Calophyllum inophyllum. Infrequent canopy mucronata stands are common on the lagoon trees include Guettarda speciosa, Premna ser­ sides, along channels between islets, and occa­ ratifolia, and Terminalia catappa, with the sionally on the ocean coasts of the wetter understory dominated by Scaevola sericea, larger islands ofButaritari, Abaiang, Tarawa, M orinda citrifolia, and Dodonea viscosa, the Abemama, Aranuka, Nonouti, Tabiteuea, parasite Cassytha filiformis, Psi/otum nudum, and Onotoa. All these islands have areas of and the ferns Polypodium scolopendria and sheltered muddy lagoon flats, lagoon margins, Nephrolepis biserrata. Also occasional in open and fishponds. Such areas are commonly sites is Phyllanthus societatis. Exotic species bordered by extensive stands of Pemphis dominant in disturbed sites include Psidium acidula, which commonly grows to just above guajava, Lantana camara, and two herbaceous the high water line (Luomala 1953, Catala species, Euphorbia hirta and Desmodium tri­ 1957, Moul 1957, Fosberg ca. 1972). Bru­ florum (Manner et al. 1984, 1985). guiera gymnorhiza is reportedly also present In the Gilberts there is essentially no re­ in mangrove associations on Butaritari, Abe­ maining primary forest; all ofit, except for the mama, and Tabiteuea (Fosberg and Sachet rare relict stand or individual tree, has been 1987). Other mangrove species present in the replaced by coconut-dominated vegetation. Gilberts include Lumnitzera littorea, which is There is evidence that the dominant inland found in salt swamps on Butaritari, and Son­ forest species was probably Pisonia grandis, neratia alba, which grows on the ocean side of the typical woodland on many atolls (Fosberg Butaritari and is also reported from Marakei 1952, Woodroffe 1985). Other elements in­ (Overy et al. 1982, Fosberg and Sachet 1987). clude Calophyllum inophyllum and Hernandia A single mature L. littorea, possibly deliber­ nymphaeaefolia as the dominants; Barringtonia ately planted, was present in a roadside de­ asiatica, Macaranga carolinensis, and Termi­ pression in Eita village, Tarawa, in 1989. No nalia samoensis, which are uncommon today mangrove species have been reported from the but were probably important components Vegetation of Nauru and the Gilbert Islands-THAMAN 137 previously; and Guettarda speciosa, Pandanus Nauru's coastal strip. In the Gi!berts they are tectorius, Scaevola sericea, and Premna serrati­ found on both the major inhabited islands and folia, which are still common today and were on uninhabited islets. In most cases, particu­ undoubtedly important components (Catala larly in Nauru, the plantations are composed 1957, Thaman 1990a). Pipturus argenteus, ofrandomly scattered trees ofvarious heights although possibly an aboriginal introduction, and ages. In the Gilberts dense stands with an and Acalypha amentacea var. grandis, both almost continuous canopy are often found on reported present in the Gilberts and common limestone soils, both near the lagoon and on other atolls, could have also been a along roads. More recent plantings, many of subcanopy component of the original forest. which were done under the Department of Hibiscus tiliaceus and Terminalia catappa, Agriculture's Grove Improvement and Re­ which are considered exotics on many atolls planting Programs, are more regularly spaced (Whistler 1980a, 1987) and which are still and ofsingle age classes. These plantings now found in some areas in the Gilberts, could constitute a major proportion of the area have been components in some forests. Pisonia under coconuts in the Gilberts (Sewell 1979). grandis, which in some cases is protected as In poorly maintained groves, coconut seed­ bird reserves, is found in relict stands on lings and fallen leaves and husks dominate Onotoa (Moul 1957, Sachet 1983, Wester the understory. In the more well-maintained 1985, Woodroffe 1985). groves, the soil surface has a sparse cover of grasses and herbs including Thuarea involuta, Lepturus repens, Stenotaphrum micranthum, Limestone Escarpment or Pinnacle Vegetation Fimbristylis cymosa, Euphorbia spp., Boer­ havia spp., Sida fallax, Triumfetta procum­ The dominant species on the limestone cliffs bens, and the exotic Cenchrus echinatus. Coco­ of the escarpment and on emergent pinnacles nut stands near the seaward sides and toward on Nauru is Ficus prolixa, with Terminalia the centers ofislets are often more open. They catappa, Ochrosia elliptica, and Guettarda contain a greater number of understory spe­ speciosa constituting important second-stra­ cies including Tournefortia, Guettarda, Pan­ tum species (Manner et al. 1985). Isolated danus, and Scaevola, with young coconuts, relict stands of Barringtonia asiatica and and denser, almost continuous stands of the Pisonia grandis are also found along the crest same grasses and herbs often present. Cas­ of the escarpment above Anibare Bay. The sytha filiformis and Laportea ruderalis are ferns Nephrolepis biserrata and Polypodium occasional, while Psilotum nudum and Poly­ scolopendria and the liana Ipomoea micran­ podium scolopendria are more often found in thra are locally abundant, and the herb the shade and at the bases of coconut trees. Laportea ruderalis is found in moist shady Dodonea viscosa is sometimes found in dense habitats at the base ofthe escarpment. On the stands or as isolated individuals (Catala 1957, more gradual-sloping colluvial portions ofthe Moul 1957), especially near sites of existing escarpment, almost impenetrable thickets of or former village settlements (Catala 1957, Hibiscus tiliaceus are found. Understory spe­ Overy et al. 1982). The density and composi­ cies include Colubrina asiatica and Tacca tion of such vegetation varies, of course, leontopetaloides. In Anetan District, in the depending on the maintenance and density of north (Figure 1), Clerodendrum inerme fes­ coconut plantings. Scaevola sericea, for exam­ toons limestone outcrops and cliffs. ple, covered over a third of the area under coconuts on Tabiteuea North in the early Coconut Palm-Dominated Agricultural 1970s and forms a dense undergrowth, unless Lands cleared (Geddes 1975). Trees occasionally found as scattered indi­ Coconut groves are the major vegetation viduals, but most certainly more numerous in type in the Gilberts and, although far less the past, possibly as components ofthe domi­ important today than in the past, neglected nant presettlement and pre-European-contact plantations are found in a number of sites on vegetation, include Calophyllum inophyllum, 138 PACIFIC SCIENCE, Volume 46, April 1992

Cordia subcordata, Hernandia nymphaeae­ gatum, Cordyline fruticosa, Crinum spp., folia, Pisonia grandis, and Premna serratifolia. Delonix regia, Dieffenbachia spp., Hibiscus These species have been almost totally re­ rosa-sinensis, Hosta plantaginea, Hymenocal­ placed in the drive, over the past 40 years, lis littoralis, Ixora spp., Jasminum sambac, to extend coconut plantings (Catala 1957, Jatropha integerrima, Nerium oleander, Pen­ Thaman I 990a). Instead, clearings or open tas spp., Plumeria spp., Polyscias spp., Pseu­ areas in the coconut canopy are commonly deranthemum caruthersii, Psidium guajava, occupied by thickets of Scaevola and Guet­ Sanseviera trifasciata, Tabernaemontana diva­ tarda, or by planted Pandanus groves or indi­ ricata, Tecoma stans, and Thunbergia erecta. vidual pandanus or native fig (Ficus tinctoria) The houseyard gardens ofI-Kiribati, Tuva­ trees, both important staples, particularly in luan, Chinese, and Filipino contract workers, the drier southern islands. and in the European and Indian expatriate Planted groves ofedible Pandanus tectorius communities of Nauru, are very different. cultivars in forest clearings, both on the pla­ Each reflects distinctive preferences in food teau and on the more gradually sloping areas and ornamental plants, and they are common­ ofthe escarpment, were also once a prominent ly dominated by food plants. I-Kiribati and feature of Nauru's agricultural vegetation. Tuvaluan gardens at Location usually con­ Today, they are restricted to a few relict sist of a single banana, coconut, papaya, or groves, some of which were found to be breadfruit tree, or a few cassava, sweet potato, present in the unmined areas of Anibar Dis­ taro, tannia (Xanthosoma sagittifolium), pine­ trict in 1980. apple, sugarcane, hibiscus spinach (Hibiscus manihot), or chili pepper (Capsicum frutes­ Houseyard and Village Gardens cens) plants. All are often grown in boxed or fenced areas filled with imported soil or Houseyard and village gardens contain a mulch. Chinese gardens at Location focus greater proportion ofaboriginal cultigens and more on short-term vegetable plants, such as recently introduced exotics, with greater di­ Chinese cabbages (Brassica spp.), onions and versity in Nauru mainly because ofits greater garlic (Allium spp.), amaranth spinach (Ama­ urbanization and contact with overseas ranthus spp.), coriander (Coriandrum sati­ sources of nonquarantined planting mate­ vum), long beans (Vigna sesquipedalis), and a rials. range of cucurbits. Filipino workers plant In indigenous Nauruan houseyard gardens Dolichos lablab, sweet potato, and Moringa the dominance of recently introduced orna­ oleifera. European expatriates plant toma­ mental species is pronounced, with some 118 toes, lettuce, and parsley, whereas the ex­ of 140 species classed as recent introductions. panding Indian expatriate community has Indigenous species include Abutilon indicum, planted eggplant (Solanum melongena), okra Barringtonia asiatica, Calophyllum inophyl­ (Hibiscus esculenta), horseradish tree (Morin­ lum, Cerbera manghas, Clerodendrum inerme, ga oleifera), and Averrhoa belimbi. A similar Cordia subcordata, Ficus prolixa, Guettarda range of food species is cultivated behind the speciosa, M orinda citrifolia, Ochrosia elliptica, work shops on Topside, although the number Premna serratifolia, and Terminalia catappa, and areas under crops are greater, with some which in some cases, such as with Cerbera gardeners growing taro, tannia, and giant manghas and Cordia subcordata, are only swamp taro, employing the traditional inten­ present today in Nauru in houseyard gardens. sive mulching systems of the Gilberts and Common food plants include, in order of Tuvalu (Thaman 1987b, 1988a). importance, coconut, breadfruit, bananas, Although exotic ornamentals are common pandanus, papaya, Citrus spp., and guava. in areas immediately surrounding dwellings in Common ornamentals, found in at least four the Gilberts, particularly in highly urbanized of 16 sample gardens, include Acalypha amen­ South Tarawa, the dominant plants are im­ tacea, Bougainvillea spp., Caesalpinia pulcher­ portant tree crops: coconut palms (often rima, Caladium bicolor, Casuarina equiseti­ planted for toddy production), pandanus, folia, Catharanthus roseus, Codiaeum varie- papaya, native fig (Ficus tinctoria), and Vegetation of Nauru and the Gilbert Islands-THAMAN 139 breadfruit (Artocarpus altilis and A. marian­ Gilberts. Major contributing factors include nensis). The latter two are found almost ex­ (1) long settlement; (2) destruction during clusively in villages around dwellings and World War II; (3) increasing urbanization and bordering roads, with most families on the transportation network development (e.g., wetter islands such as Butaritari having at roads, causeways, and airfields); (4) total veg­ least one large breadfruit tree (Sewell 1979). etation clearance and the use of heavy equip­ On the drier southern islands, where bread­ ment, particularly in the case ofthe phosphate fruit does not grow well, pandanus and Ficus industry; and (5) the widespread practice of tinctoria are dominant on the village periph­ keeping villages and plantations clean by ery (Catala 1957). Other food plants found continuous burning, sweeping, and clearing of in village gardens include giant swamp taro vegetation. These have created extensive areas (Cyrtosperma chamissonis), which is also culti­ of ruderal vegetation in settlements, waste vated in pits within villages. Less widely culti­ places, along roadsides and airstrips, and in vated food plants include sweet potato, cassa­ areas associated with pre-mining vegetation va, pumpkin (Cucurbita pepo), lime (Citrus clearance in Nauru. The dominant species in aurantiifolia, the one citrus species that seems most areas are grasses, annuals, and shrubby to do well in alkaline atoll soils), sugarcane, weedy species. hibiscus spinach (Hibiscus manihot), and a Species common in both Nauru and the range of short-term vegetables, such as cab­ Gilberts include (1) the grasses Cenchrus bages (Brassica spp.), long beans (Vigna echinatus, Chloris inflata, Cynodon dactylon, sesquipedalis), and cucurbits. The latter group Dactyloctenium aegyptium, Digitaria spp., has been promoted in hydroponic and mul­ Eleusine indica, Eragrostis amabilis, and Lep­ ching programs to increase supplies of nutri­ turus repens; (2) the sedges Cyperusjavanicus, tious vegetables. C. rotundus, and Fimbristylis cymosa (which Indigenous species commonly planted or along with Digitaria setigera and Lepturus protected in I-Kiribati houseyard gardens, repens are probably indigenous); and (3) the villages, and urban areas include M orinda herbaceous species Amaranthus dubius, A. citrifolia; Premna serratifolia, Scaevola seri­ viridis, Bidens pilosa, Cassia occidentalis, cea, Tournefortia argentea, and Clerodendrum Crotalaria spectabilis, Euphorbia spp., Passi­ inerme (which is commonly planted as a flora foetida, Phyllanthus amarus, Physalis hedge), and the ferns Nephrolepis spp. and spp., Portulaca oleracea, Sida rhombifolia, Polypodium scolopendria. Less common are Spermacoce assurgens, Stachytarpheta urti­ Barringtonia asiatica, Calophyllum inophyl­ caefolia, Synedrella nodiflora, Tridax procum­ lum, Cordia subcordata, Terminalia catappa, bens, and Vernonia cinerea, plus the indigenous and T. samoensis. Common exotic ornamen­ parasite, Cassythafiliformis. tals include Acacia farnesiana, Acalypha Weedy species common only in Nauru in­ amentacea vars., Bougainvillea spp., Calo­ clude Ageratum conyzoides, Alysicarpus va­ tropis gigantea, Catharanthus roseus, Crinum ginalis, Cleome rutidosperma, C. viscosa, asiaticum, Dracaena spp., Hibiscus rosa­ Crotalaria goreensis, Desmodium tortuosum, sinensis, Hymenocallis littoralis, Ixora casei, Hedyotis corymbosa, Indigofera hirsuta, Mal­ Jasminum sambac, Lantana camara, Mirabilis vastrum coromandelianum, Phyllanthus socie­ jalapa, Nerium oleander, Ocimum spp., Plec­ tatis, and Tricholena rosea. Weedy species tranthus scutellarioides, Polyscias spp., Pseu­ common in the Gilberts include Cyperus deranthemum spp., Rhoeo spathacea, Russelia polystachyos, Ludwigia octovalvis, and the equisetiformis, and Tecoma stans. The flowers indigenous species Boerhavia spp., Euphorbia or leaves of most of these plants are used for chamissonis, Laportia ruderalis, Paspalum dis­ body ornamentation. tichum, Sida fallax, and Triumfetta procum­ bens. Of particular interest are the shrubby species Pluchea indica and P. carolinensis, and Ruderal Vegetation a hybrid ofthe two, all ofwhich have become Extensive areas ofhighly disturbed ruderal naturalized in ruderal habitats in the Gilberts; vegetation are found in both Nauru and the and the fact that whereas Acacia farnesiana 140 PACIFIC SCIENCE, Volume 46, April 1992 and Lantana camara are both naturalized and 10 m long and 3 to 6 m wide. Weedy plants weedy in Nauru, they are only found culti­ found in these pits include Ludwigia octo­ vated in houseyard gardens in the Gilberts. valvis, Eleocharis geniculata, and Cyperus lae­ A few tree or treelike species have become vigatus, the latter particularly common in naturalized in dense stands in Nauru. Man­ abandoned pits. Tournefortia argentea, one of gifera indica is dominant in dense forests the main sources of leaf compost used in te behind residences in the Buada Lagoon de­ babai cultivation, is also occasionally found pression; Annona muricata and A. squamosa near pits (Moul 1957). form dense stands on gradually sloping areas On the wettest island, Butaritari, however, of the escarpment; Adenanthera pavonina, areas ofte babai pits per household were much Lantana camara var. aculeata, Leucaena leu­ greater, with only limited or periodic evidence cocephala, and Psidium guajava form dense of neglect or serious underutilization, some stands or thickets between Buada Lagoon and households having over 2000 m 2 in productive the decalcination plant on the coastal strip pits (Sewell 1979). in Aiwo District; and Casuarina equisetifolia and Muntingia calabura have colonized road­ Phosphate-mined Lands side areas and portions of the phosphate­ mined area. Ofparticular interest is the almost As a result of almost 80 years of open-cast monospecific colonization ofthe large topsoil phosphate mining, some three-quarters of stockpile on Topside by the cucurbit Luffa Nauru is under severely modified disclimax acutangula. vegetation in various stages of succession. Before mining, the vegetation is removed by bulldozer and the topsoil removed to expose Giant Swamp Taro or Babei Pits the phosphate deposits that lie between coral­ In the central areas of the main Gilbert limestone pinnacles. The extraction of phos­ Islands, and in and around villages, are exten­ phate then causes dramatic changes in local sive areas of pits for the cultivation of the relief, which varies between 4 and 8 m from ceremonial staple, giant swamp taro or te the top of the pinnacles to the pit bottoms, babai (Cyrtosperma chamissonis). These pits with about three to four pinnacles occurring 2 have been excavated to the level of the fresh­ within each 100 m • Because mining is only water lens, through the limestone bedrock to about 20% efficient, unconsolidated phos­ depths of 1.5 to over 4 m. Because of in­ phate deposits remain in the pit bottoms and creasing salinity and the declining importance on the saddles and scree slopes between the of te babai relative to copra production, cash pinnacles. These deposits (which might be employment, and imported food, many ofthe mined at a later date) and the pinnacle sur­ pits on some islands have been abandoned. In faces constitute the main sites for recoloniza­ some cases, such as on Onotoa, this occurred tion (Manner et al. 1984, 1985). so long ago that the inhabitants have no Although there is widespread evidence that recollection oftheir origin (Catala 1957, Moul exotics commonly replace indigenous species 1957, Thaman 1990a). On Abemama, for in highly disturbed habitats, the Nauru study example, a survey of 16 households revealed by Manner et al. (1984, 1985) supports the that whereas the mean number of pits in use conclusion of Mueller-Dombois (1975) that was only 4.2, the mean number of empty pits indigenous (pioneer) species are often better per household was 23.4, with only 7.7 still adapted to edaphically harsh environments, containing sufficient water to produce te given the cessation ofhuman disturbance. The babai. Moreover, few of the productive pits study by Manner et al. shows a very rapid were fully stocked, thus "reflecting more basi­ colonization of mined areas by exotic herbs cally the changing food preference and habits and ferns, followed by a fairly rapid replace­ ofgrowing reliance on the cash component of ment by native, primarily coastal strand, spe­ a household's total income" (Watters and cies. Banabati 1977). Pits ranged in size from 8 to Early pioneer species include the nonwoody Vegetation ofNauru and the Gilbert Islands-THAMAN 141

exotics Alysicarpus vaginalis, Cleome rutido­ before the next century, to provide the phos­ sperma, Crotalaria goreensis, Emilia sonchi­ phate needed to revive phosphate-poor soils folia, Eragrostis amabilis, Euphorbia cyatho­ to fuel the development ofAustralia and New phora, E. hirta, E. prostrata, Hedyotis corym­ Zealand. bosa, Syndrella nodiflora, Tricholena rosea, Tridax procumbens, and Vernonia cinerea, plus the indigenous ferns Nephrolepis biser­ THE FLORAS rata and Polypodium scolopendria. Of these, Like the extremely limited, degraded, only the two fern species and Euphorbia hirta, and displaced vegetation types, the indige­ E. prostrata, Tricholena rosea, Tridax pro­ nous terrestrial floras of Nauru and the Gil­ cumbens, and Vernonia cinerea remain signifi­ bert Islands exhibit extreme poverty and cur­ cant components ofthe flora in the later stages rent numerical domination by exotics. Of a of succession, usually in open disturbed sites. total of487 and 306 species present on Nauru Species entering the succession early and and the Gilberts, respectively, only 55 (11.3%) remaining dominants in the 40- to 80-year-old and 83 (27.1 %), respectively, are possibly sites include the trees Calophyllum inophyllum, indigenous (Table 1). There are no reported Dodonea viscosa, Ficus prolixa, Guettarda endemics, reflecting the lack of habitat diver­ speciosa, M orinda citrifolia, and Premna ser­ sity and the predominance of ubiquitous, ratifolia; the shrubs Phyllanthus societatis and easily dispersed pantropical or paleotropical Scaevola sericea; the grasses and sedges Lep­ coastal species. The greater diversity in the turus repens, Fimbristylis cymosa, and Cyperus Gilberts is probably the result ofgreater total javanicus; the parasite Cassythafiliformis; and land area, greater coastal habitat diversity, the diminutive fern Ophioglossum petiolatum. and less coastal habitat degradation over All are indigenous. Larger exotics found in the time. The high number ofrecent introductions later stages of succession in more open in Nauru reflects its greater contact with the habitats include Lantana camara, Psidium outside world, increasing urbanization, and guajava, and Stachytarpheta urticaefolia. the total absence of quarantine regulations The study suggests that the potential natu­ there. ral disclimax vegetation of the open-cast mined plateau will probably be dominated Nature ofIndigenou~ Species by Calophyllum inophyllum and Guettarda speeiosa, with the epiphytic Ficus prolixa do­ Of the indigenous species (Table 1), eight minating the more ecologically severe pinna­ are widespread pantropical or paleotropical cle habitats. Morinda eitrifolia, Premna ser­ pteridophytes, including Psi/otum nudum, ratifolia, and the exotics Lantana camara and Polypodium scolopendria, and Ophioglossum, Psidium guajava could become important Pteris, and Nephrolepis spp., with Pyrrosia components of the subcanopy. The exotics adnascens, a common epiphyte found on Nau­ Casuarina equisetifolia (which is native to ru. There are no indigenous gymnosperms, limestone habitats on other Pacific islands) although the widespread Cycas eireinalis is and Muntingia calabura, both now locally found in cultivation. Indigenous monocotyle­ abundant in some mined areas, could enter dons are restricted to Pandanus tectorius, into the succession as well. some cultivars of which are undoubtedly ab­ As argued by Manner et al. (1985), given no original introductions, and a range of sedges deliberate human intervention, the succession and grasses (Cyperaceae and Poaceae), some to a disclimax vegetation association capable of which could be aboriginal or recent intro­ of sustaining human life will probably take ductions. The coconut palm (Cocos nucifera) "many thousands ofyears." It is stressed that is classified as an aboriginal introduction. it is ironic that Nauru's central plateau, from The dicotyledons are composed almost ex­ which Nauruans formerly obtained some of clusively of salt-tolerant, widely dispersed, the necessities of life, will be a "topographic pantropical coastal species. A large propor­ jungle" stripped of its natural vegetation, tion of these species (28 of 55 for Nauru and 142 PACIFIC SCIENCE, Volume 46, April 1992

TABLE 1 TABLE 1 (continued) SPECIES THAT ARE INDIGENOUS OR POSSIBLY INDIGENOUS TO NAURU AND KIRIBATI SPECIES NAURU KIRIBATI Shrubs SPECIES NAURU KIRIBATI Abutilon asiaticum var. albescens +e +e Pteridophytes Abutilon indicum +e? Asplenium nidus +e? +e Allophylus timoriensis +e Nephrolepis biserrata + + Caesalpinia bonduc +e +e Nephrolepis hirsutula + + Capparis cordifolia + Ophioglossum nudicaulis + Clerodendrum inerme + + Ophioglossum petiolatum + Colubrina asiatica + Polypodium scolopendria + + Dodonaea viscosa + + Psilotum nudum + + Euphorbia chamissonis +e +e Pteris ensiformis +e +e Pemphis acidula + Pteris tripartita + + Phyllanthus societatis + Pyrrosia adnascens +e Polyscias grandifolia +e Herbs Scaevola sericea + + Achyranthes canescens E? +e Sidajallax +e + Adenostema lanceolatum +e Sophora tomentosa +e Boerhavia albiflora +e Suriana maritima +e + Boerhavia repens + Trees Boerhavia tetrandra + Aidia cochinchinensis +e +e Hedyotis biflora +e Barringtonia asiatica +e +e Hedyotis verticil/ata + Bruguiera gymnorhiza +e + Laportea ruderalis +e + Calophyllum inophyllum + + Portulaca australis + Cerbera manghas +e +e Portulaca lutea +e Cordia subcordata +e + Sesuvium portalucastrum +e Erythrina variegata +e Tribulus cistoides +e Fagraea berteriana E? +e? Triumjetta procumbens + + Ficus prolixa + +e? Wollastonia biflora +e Ficus tinctoria + Grasses and Sedges Guettarda speciosa + + Cyperus iria +e Hernandia nymphaeaejolia +e +e Cyperus javanicus +? + Hibiscus tiliaceus + + Cyperus laevigatus +? Inocarpus jagifer +e? Cyperus polystachyos + Lumnitzera littorea +e Digitaria pacifica +e Macaranga carolinensis +e Digitaria setigera +? +? Morinda citrifolia + + Eragroslis whitneyi +e Neisosperma oppositifolia +e Fimbristylis cymosa + + Ochrosia e//iptica +e Fimbristylis dichotoma +e Pandanus tectorius + + Lepturus pilgerianus + Pipturus argenteus +e Lepturus repens + + Pisonia grandis +e + Paspalum distichum + Premna serratifolia + + Stenotaphrum micranthum + Rhizophora mucronata + Thuarea involuta +e Sonneratia alba +e Terminalia catappa +? +? Vines and Lianas Terminalia samoensis +e Canavalia cathartica +e +e Thespesia populnea + +e Canavalia rosea +e Tournejortia argentea + + Capparis quiniflora +e Vitex negundo +e +e Cassytha./iliformis + + Vitex trifolia +e Derris trifoliata +e Total species 55 83 Ipomoea littoralis +e +e Ipomoea macrantha + + NOTE: ? = status uncertain, possibly an aboriginal or recent Ipomoea pes-caprae + + introduction; E = possibly extinct; e = endangered. Vigna marina + + SOURCES: An extensive review of the available literature and personal records and observations by the author; see in particular Thaman 19890, I990b. Vegetation of Nauru and the Gilbert Islands-'fHAMAN 143

40 of 83 for the Gilberts) are severely re­ Pacific atolls range from as few as three to stricted in distribution, endangered, or possi­ perhaps 150 indigenous species, compared to bly extinct, because of removal and severe some Indian Ocean atolls, nearer to continen­ habitat modification or limitation (Table I). tal areas, which have close to 300 indigenous Many species still found in the Gilberts were species (Fosberg 1952). probably present in the past in Nauru, but are The floristic poverty of Nauru and the now extinct. Species such as Abutilon asia­ Gilberts becomes even more pronounced ticum, Caesalpinia bonduc, Euphorbia chamis­ based on a comparison of the occurrence of sonis, Sida fallax, Suriana maritima, Aidia 142 widespread coastal species in II Pacific cochinchinensis, Barringtonia asiatica, Cer­ island groups (Table 2). All of these species bera manghas, Hernandia nymphaeaefolia, have the ability to cope successfully in en­ Pisonia grandis, Thespesia populnea, and vironments characterized by loose shifting Vitex negundo are represented by only a few sands, wave action, soil-less limestone and remaining individuals, often in houseyard volcanic terraces and rock outcrops, high gardens, or by localized relict communities. salinity, strong sunlight, strong winds, sea Moreover, some of the plants reported pres­ spray and associated physiological drought ent in Kiribati may not actually be present as (Fosberg 1952, 1960), and, in some cases, indigenous species in the main Gilbert group, periodic inundation and waterlogging, all but, rather, as deliberate introductions, or conditions common in Nauru and the citations from Banaba that have been in­ Gilberts. cluded in "Kiribati" lists. For example, Wol­ The island groups range from large, geo­ lastonia biflora and Abutilon spp., which are graphically older high island groups such as reported from Tarawa (Fosberg and Sachet Fiji, composed ofover 300 islands with a total 2 1987) but not seen by recent collectors, are area of 18,376 km , to the three small isolated known locally as te kaura ni Banaba, the"Sida atolls ofTokelau with a total land area ofonly 2 fallax from Banaba" (Overy et al. 1982, 12.2 km • Also included are high island Thaman 1987a). Similarly, Ochrosia elliptica, groups with diverse habitats, such as Guam, which is present today on Nauru, has also a volcanic island with extensive areas of lime­ 2 been reported present on Banaba, but not in stone and an area of 549 km ; Samoa the Gilbert group. Before widespread distur­ and Hawaii, recent basaltic volcanic island bance in both areas, Nauru and the Gilberts groups, with little or no limestone; Palau, would have undoubtedly had more species in a group of some 340 volcanic and up­ common. lifted limestone islands, including an atoll, Kayangel, and the raised phosphate island of Angaur, located only 850 km to the east ofthe Comparison with Other Island Floras Philippines; Tonga, a group of about 150 The extreme poverty of the indigenous uplifted limestone and some volcanic islands, 2 floras of Nauru and the Gilbert Islands be­ with a total area of697 km ; Niue, an isolated comes more obvious when compared with uplifted limestone island, like Nauru, but with estimates of the indigenous floras of island an area of 258 km2 and few beaches; and groups that are larger or closer to the plant Makatea, an uplifted phosphatic island about source regions, such as Malaya (ca. 20,000), the same area as Nauru and without protec­ the Philippines (10,000), Bismarck Archipela­ tive barrier reefs or lagoons. go (700), Vanuatu (750), Fiji (more than Although these comparisons are strongly 1100), Tonga (257), Samoa (548), and French biased by size and geologic age, their distance Polynesia (600). Only extremely isolated small from plant source areas, and the availability islands such as Easter Island and the three of information on other islands such as small atolls ofTokelau, with indigenous floras Banaba, the poverty of the coastal floras of of32 and 33 species, respectively, have poorer the two small phosphate islands ofNauru and floras (Good 1947 in Manner 1987, Parham Makatea and the atolls of the Gilbert and 1971). When taken individually, the floras of Tokelau islands is clearly apparent: only 58 TABLE 2

NATURE AND GEOGRAPHICAL OCCURRENCE IN SELECTED ISLAND GROUPS OF WIDESPREAD COASTAL PLANT SPECIES OF THE TROPICAL PACIFIC OCEAN

SPECIES FIJI TONGA SAMOA GUAM HAWAII NIUE PALAU MAKATEA TOKELAU NAURU KIRIBATI TOTAL

Ferns Acrostichum aureum + + + + * + + - - - - 6(1) Asplenium nidus + + + + + + + + + *? + 10(1) Davillia solida + + + + * + + + + - - 8(1) Nephrolepis spp. + + + + + + + + + + + 11 Polypodium scolopendria + + + + + + + + + + + 11 Pteris spp. + + + + + + + - - + + 9 Pyrrosia adnascens + + + + --- - + 5 Stenochlaena palustris + + ---- + - - - - 3 Tectaria spp. + + + + - + + - - - - 6 Thelypteris spp. + + + + + + + - - - - 7 Total present (x/IO) 10 10 9 9 7 8 9 4 4 5 4

Herbs Achyranthes spp. *** + ** + ** +? + 4(7) Boerhavia spp. + + + + + + + + + - + 10 Crinum asiaticum *********** -(II) Dendrobium spp. + + + + -- + - - - - 5 Hedyotis spp. + + + + + + + - + - + 9 Heliotropium spp. -- + + + + + - + - 6 Hymenocallis littoralis ******* - ** -(9) Laportea (Fleurya) spp. + + + + *? *? + + + + + 9(2) Lepidium bidentatum - --- + -- + - - - 3 Peperomia spp. + + + + + + + + - - 8 Portulaca lutea + + + + + + - + - - + 8 Portulaca pilosa +? + + + + + + - + - + 9 Procris pedunculata + + + + - + + + + - - 8 Sesuvium portalucastrum + + - + + + - - - + 6 Tacca leontopetaloides * ********** -(II) Taeniophyllum fasticola + + + + - + + + - - 7 Triumfetta procumbens + + + + + + + + + + + 11 Total present (x/17) 15 15 14 16 14 15 14 12 9 6 11

Grasses/Sedges Cyperus javanicus + + + + ** + + - ** 5(4) Cyperus laevigatus + + + - + + - - - - + 6 Cyperus polystachyos + + + * + - * - - - + 5(2) Digitaria setigera + + + + ** + + + + + 9(2) Eleocharis spp. + + + + + - + - - - - 5 Fimbristylis cymosa + + + + + + + - + + + 10 Ischaemum spp. + + + + + + + - - - - 7 Lepturus repens + + + + + + + + + + + 11 Paspalum distichum + + + + * + + - - - + 8(1) Sporobolus spp. + - + + - + + - * * 5(2) Stenotaphrum spp. + + + -- + + - - - + 6 Thuarea involuta + + + + -- + - - + 6 Total present (x/12) 12 11 11 10 10 8 11 4 3 5 10

Vines/Lianas Abrus precatorius + + + + * + + + - - 7(1) Canavalia cathartica + + + + * - + - - + + 7(1) Canavalia rosea + + + + * + + - - + - 7(1) Canavalia sericea + + + - + + - - - - - 5 Cassytha filiformis + + + + + + + + + + + 11 Derris trifoliata + + + + * - + - - + - 6(1) Entada phaseoloides + + + + * - + - - - - 5(1) Epipremnum pinnatum + + + - * ------3(1) Hoya australis + + + - * ------3(1) Ipomoea littoralis + + + + + + + + - + + 10 Ipomoea macrantha + + + + * + + - + + + 9(1) Ipomoea pes-caprae + + + + + - + - - + + 8 Mucuna gigantea + + + + + + + - - - - 7 Vigna marina + + + + + + + - - + + 9 Total present (x/14) 14 14 14 11 14 8 11 3 2 8 6

Shrubs Abutilon spp. + -- * + + - - - + + 4(2) Acanthus ebracteatus ------+ - - - -I Allophylus timoriensis + + + + - + + + - - + 8 Bikkia tetrandra + + - + -- + - - - - 4 Caesalpinia spp. + + + + + + + - - + +' 9 Canthium spp. + + + + + - + + - - - 7 Capparis spp. + + + + + + + + - + - 9 Clerodendrum inerme + + + + * + + - - + + 8(1) Colubrina asiatica + + + + + + + + - + - 9 Dalbergia candenatensis + + - + -- + - - - - 4 Desmodium umbellatum + + + + - + + - - - - 6 Dodonea viscosa + + + + + + + + - + + 10 Eugenia reinwardtiana + + + + + + + - - - - 7 Euphorbia chamissonis + + + + - + + - - + + 8 Gardenia taitensis + + + - * + - * + * * 5(4) Geniostoma spp. + + + + - + + - - - - 6 TABLE 2 (continued)

SPECIES FIJI TONGA SAMOA GUAM HAWAII NIUE PALAU MAKATEA TOKELAU NAURU KIRIBATI TOTAL

Nypa fruticans --- ** - + - - 1(2) Pemphis acidula + + + + * + + + + + 9(1) Scaevola sericea + + + + + + + + + + + 11 Sida spp. + + + * + + - - - + + 6(1) Sophora tomentosa + + + + -- + - - + 6 Suriana maritima + + - + -- + + - + + 7 Tephrosia purpurea + + + + * + - - - - - 5(1) Timonius spp. + + + + - + + + - + - 8 Wollastonia biflora + + + + - + + - - + 7 Wikstroemia spp. + + + + + - + - - - 6 Ximenia americana + + + + - + - - - 5 Total present (x/27) 25 24 21 24 15 19 24 11 3 11 13

Trees Acacia simplex + + + - -- - - 3 Aidia cochinchinensis + + + + - - + - + + 7 A vicennia alba - - + ------2 Barringtonia asiatica + + + + * + + + + + + 10(11) Barringtonia racemosa + - + + * + + - - - - 5(6) Bruguiera gymnorhiza + + + + * - + + + 7(8) Calophyllum inophyllum + + + + + + + + + + + 11 Casuarina equisetifolia + + + + ** + ** ** 5(11) Cerbera manghas + + + - * - + - + + 6(7) Ceriops tagal - - + - - - - 1 Cocos nucifera * ****** **** (11) Cordia subcordata + + + + * + + + + + + 10(11) Cycas circinalis + + + + ** + - ** 5(9) Cynometra spp. + -- + * - + - - - 3(4) Diospyrosferrea + + + - + + + - - 6 Dolichadrone spathacea --- * - + - - - 1(2) Erythrina fusca + + + - * - * - - 3(5) Erythrina variegata + + + + * + + - + - 8(9) Excoecaria agallocha + + + + - + + - - - - 6 Ficus obliqua + + + -- + - - - 4 Ficus prolixa + + + + + + + - + + 9 Ficus scabra + + + -- + - - - 4 Ficus storkii + + + - + - - - 4 Ficus tinctoria + + + + + + - + * + 8(9) Glochidion spp. + + + + - + + + - 7 Grewia crenata + + + + - + - - - 5 Guettarda speciosa + + + + * + + + + + + 10(11) Gyrocarpus americanus + + + ------3 Heritiera littoralis + + - + * + + - - - - 5(6) Hernandia nymphaeaefolia + + + + * + + + + + + 10(11) Hibiscus tiliaceus + + + + + + + + - + + 10 Inocarpus fagifer + + + **** - - - * 3(8) Intsia bijuga + + + + * - + - - - - 5(6) Leucaena insularum + + - + + + - - - 5 Lumnitzera littorea + + - + -- + - - + 5 M ammea odorata + - + + * - + + - - 5(6) Manilkara spp. + + ---- + - - - - 3 Metroxylon spp. + *** - +? - - 2(5) Morinda citrifolia + + + + * + + + + + + 10(11) Neisosperma oppositifolia + + - + * + + - + - + 7(8) Pandanus tectorius + + + + + + + + + + + II Phaleria disperma (spp.) + + + - ** + - - - 4(6) Pipturus argenteus (spp.) + + + + + + + + * - + 8(9) Pisonia grandis + + + + - + + - + + + 9+ Pittosporum spp. + + - + + + + - - - 6 Planchonella costata (spp.) + + + + - + + + - - 7 Polyscias spp. + + + + + + - + 7 Pongamia pinnata + + + * - + - - 4(5) Premna serratifolia + + + + - + + + - + + 9 Rhizophora spp. + + + + * - + + - - + 8 Santalum spp. + + -- + ** - - - 3(5) Serianthes spp. + + - + - + - - 4 Sonneratia alba ------+ - - + 2 Soulamea amara ------+ - - I Syzygium spp. + + + + + + + - - - 7 Terminalia catappa + + + + * + + + + + + 10(11) Terminalia samoensis + + + + * - + + + - + 8(9) Thespesia populnea + + + + * + + + - + + 9(10) Tournefortia argentea + + + + * + + + + + + 10(11) Vavaea amicorum + + + ------3 Vitex spp. + + + + + + + - + + 10 Xylocarpus spp. + + + + -- + - - - 5 Total present (x/62) 57 52 48 46 38 39 54 21 16 23 30 Grand Total (x/142) 133 126 117 116 98 97 123 55 37 58 74

NOTE: Under the island groups, + = presumably indigenous, • = presumably an exotic aboriginal or recent introduction, and? = status uncertain; under total, the number outside the parentheses indicates the number ofisland groups where a given species was indigenous, whereas the number in parentheses indicates its occurrence as an exotic. SOURCES: Fiji (J. W. Parham 1972); Tonga (Yuncker 1959); Samoa (B. E. V. Parham 1972, Whistler 1980b); Guam (Stone 1970); Hawaii (Neal 1965, St. John 1973); Niue (Sykes 1970); Palau (Fosberg et al. 1980); Makatea (Wilder 1934); Tokelau (Parham 1971, Whistler 1988); Nauru (Thaman et al. 1985); Kiribati (Luomala 1953, Catala 1957, Overy et al. 1982, Fosberg and Sachet 1987); general (Fosberg et al. 1979, 1982, 1987); personal records and observations by the author; see in particular Thaman 1989a, 1990b. 148 PACIFIC SCIENCE, Volume 46, April 1992 and 55 species, respectively, are recorded from genteus, and Terminalia samoensis, most of Nauru and Makatea, and 74 and 34 species, which are present on the smaller elevated respectively, from the Gilberts and Tokelau, phosphate-rich island of Fais and the lime­ ofthe 142 commoncoastal species. In all other stone island of Satawal in the Western Caro­ island groups, including Hawaii and Niue, at line Islands (Fosberg 1969, Fosberg and least two-thirds of the 142 species are present Evans 1969), are conspicuously absent on as indigenous or long-established introduc­ Nauru. tions. There are other widespread noncoastal spe­ The Gilberts and the Tokeiaus have the cies, which might have been present in the past fewest ferns, although Nauru has the fewest on Nauru, that were present in 1932 on widespread coastal herbs. It may be assumed Makatea. These include the fern Ohioglassum that the fern Davallia solida and widespread pendulum; orchids, such as Oberonia and herbs such as Boerhavia, Hedyotis, Portulaca Taeniophyllum spp.; the herb Procris pedun­ spp., and Sesuvium portalucastrum were all culata; the vines Abrus precatorius and Dios­ originally present on Nauru, but eliminated corea bulbifera (the latter the most widespread with the widespread destruction of coastal of all yam species and present from East habitats. Nauru, the Tokelau atolls, and Africa to Micronesia and eastern Polynesia) Makatea have the fewest species of coastal (Stone 1970); and the shrubs and trees Alyxia grasses and sedges, possibly due to the combi­ sp., Canthium barbatum, Celtis paniculata, nation ofwidespread habitat destruction and Glochidion ramiflorum, Ixora sp., Melochia a relative absence of marsh or wetland en­ odorata, Planchonella (Pouteria) sp., Tarenna vironments. The widespread destruction of sambucina, and Timonius sp. (Wilder 1934). the areas around Buada Lagoon for cultiva­ Makatea has one presumably endemic spe­ tion by the Japanese during World War II cies, Euprichardia vuylstekeana, and it might may have eliminated many natural wetland be expected, given the diversity ofpre-mining environments. In the case of the Gilberts, microhabitats and the isolation ofNauru, that the widespread cultivation of Cyrtosperma there could have been endemic species there chamissonis in pits excavated down to the also. Interestingly, the one plant that was freshwater lens has provided artificial wetland thought to be possibly endemic on Nauru habitats. However, whether a given sedge turned out to be Phyllanthus societatis, "a species arrived naturally or was introduced common plant among coral rocks" on deliberately because of its cultural utility is Makatea in 1933 (Wilder 1934). uncertain. A similar comparison with the relatively There are very few vines and lianas on the undisturbed flora of Henderson Island, a atolls and Makatea. On Nauru and Niue, remote raised limestone island with a lime­ where there are virtually no beaches or coastal stone plateau and pinnacle topography, pro­ swamps, only eight of the 14 widespread vides further insight into some of the plant species occur. Abrus precatorius, Entada pha­ species that might have existed in the past on sioloides, and Mucuna gigantea are noticeably Nauru. Because it was unsuitable for perma­ absent on Nauru and in the Gilberts. nent habitation and had no economic phos­ With the exception of the Tokelau Islands phate deposits, Henderson has survived suc­ (three species) Nauru, the Gilberts, and cessive Polynesian and European impacts, Makatea have the poorest shrub flora, with with only five known introduced plant species. only II, 13, and 11 species, respectively, of a Species of widespread genera found on Hen­ possible 27 species. Similarly, there are only derson, but not on Nauru include Davillea 16 of 62 common coastal tree species in the solida; Boerhavia tetrandra, Euphorbia sparr­ Tokelaus, and only 23, 30, and 21 species, mannii, Lepidium bidentatum, Peperomia hen­ respectively, on Nauru, the Gilberts, and dersonensis, Portulaca lutea, Procris peduncu­ Makatea. The shrubs Allophylus timoriensis, lata, and Sesuvium portalucastrum; the shrubs Pemphis acidula, Sophora tomentosa, and Allophylus sp., Alyxia sp., Canthium bar­ Wollastonia biflora and the trees Ficus tinc­ batum, C. odoratum, Glochidion pitcairnense, toria, Neisosperma oppositifolia, Pipturus ar- Ixora jragrans, Jasminum didymum, Eugenia Vegetation of Nauru and the Gilbert Islands-THAMAN 149 reinwardtiana (Eugenia rariflora), Morinda tionate importance of ornamental plants umbel/ata var. forsteri, Pemphis acidula, there. Timonius polygamus, and Xylosma suaveolens The proportions of the floras composed of var. haroldii; and the trees Celtis paniculata weedy species on Nauru and the Gilberts are var. viridis, Geniostoma hendersonense, Mertya 17 and 22%, respectively, an indication of brachypoda, Pittosporum arborescens, Sesbania both the poverty of the indigenous flora and coccinea, and Santalum hendersonense. Nine the highly disturbed nature ofthe vegetation. species or varieties are presently recognized as Although food plants represent 16 and 22% endemic, all ofwhich are found in the interior. ofthe floras, respectively, because ofthe harsh These are the very areas so devastated on environments and limited focus on food pro­ Nauru. Not present on Henderson, but pres­ duction in Nauru, many of these species are ent on Nauru are Calophyl/um inophyl/um restricted in numbers or utility and are often and Barringtonia asiatica (Fosberg et al. 1983, represented by experimental attempts to di­ Fosberg et al. 1989, Pau1ay and Spencer versify food production or by individual, 1989). often immature specimens of a given species. Based on species reported present in less­ Food plants of particular importance on ei­ disturbed environments on other atolls, such ther Nauru or the Gilberts include the indige­ as those ofTuvalu (Woodroffe 1985), the Line nous species native fig (Ficus tinctoria) and Islands (Wester 1985), Tuamotu Archipelago numerous edible pandanus cultivars (Pan­ (Guerin 1982, Sachet 1983), and Bikini Atoll danus tectorius), some of which are un­ (Fosberg 1988), widespread species that might doubtedly aboriginal introductions, and the have been present in the Gilberts before habi­ aboriginal introductions coconut (Cocus nuci­ tat modification by humans include the herbs fera) and giant swamp taro (Cyrtosperma Heliotropium spp. and Lepidium bidentatum; chamissonis). Recent introductions of more the sedge Scirpus spp.; and the shrubs Timo­ localized importance, or of particular impor­ nius polygamus and Ximenia americana. tance to contract worker communities on (Note: A single mature specimen of X. Nauru or in recent urban home food produc­ americana was subsequently identified by the tion programs in the Gilberts include the author on Buota Islet, North Tarawa, in 1991 vegetables hibiscus spinach (Hibiscus manihot), after this paper was submitted.) a range of Chinese cabbage cultivars, long beans (Vigna sesquipedalis), amaranthus spin­ ach (Amaranthus spp.), and pumpkin (Cu­ Nature ofExotic Species curbita pepo); the staple root crops taro Exotic species, which constitute 89 and (Colocasia esculenta), tannia (Xanthosoma 73% of the current floras of Nauru and the saggitifolium), sweet potato (Ipomoea bata­ Gilberts, respectively, dominate the ruderal tas), and cassava (Manihot esculenta); a range and houseyard vegetation in many areas. of banana and plantain cultivars (Musa cul­ They include a wide range of ornamentals, tivars); and the tree crops lime (Citrus au­ weedy species, food plants, and a number of rantiifolia), fig (Ficus carica), guava (Psidium other useful species. guajava), mango (Mangifera indica), soursop Ornamentals, which are normally confined (Annona muricata), and the horseradish or to houseyard and village gardens, compose drumstick tree (Moringa oleifera), all ofwhich some 52 and 28 % ofthe total species recorded seem to do well in the harsh environments of from Nauru and the Gilberts, respectively. On either Nauru or the Gilberts. Important emer­ Nauru, introductions by travelers from Aus­ gency or pig foods include Polynesian arrow­ tralia, Fiji, and other areas with highly devel­ root (Tacca leontopetaloides) and purslanes oped ornamental gardening traditions; the (Portulaca spp.) and the leaves of Morinda absence of quarantine restrictions; and the citrifolia, Pisonia grandis, and Polyscias spp., almost total breakdown in the subsistence which were eaten as part of a campaign economy, coupled with the more favorable in urban Kiribati to arrest night blindness soil conditions (compared to the Gilberts), induced by vitamin A deficiency among seem to be the main reasons for the dispropor- children. ISO PACIFIC SCIENCE, Volume 46, April 1992

Other useful plants found either on Nauru nutritional requirements ofa high proportion or in the Gilberts include kapok (Ceiba pen­ ofmarine food species (Watling 1985). In Fiji tandra), cotton (Gossypium barbadense), to­ over 60% of commercially important species bacco (Nicotiana tabacum), and bamboo live in mangroves or depend on mangrove (Bambusa sp.?, which was reportedly more food webs at some stage in their life cycle (Lal abundant in the past). As suggested above, et al. 1983); in eastern Australia and Florida, some larger weedy exotics, such as Adenan­ the figures are 67 and 80%, respectively thera pavonina, Annona spp., Casuarina equi­ (Watling 1985). Destruction and reclamation setifolia, Lantana camara, Leucaena leucoce­ of mangroves have deleterious effects on phala, Mangifera indica, Muntingia calabura, fisheries yields: in the Malacca Straits man­ and Psidium guajava, some which are clas­ grove reclamation for industrial expansion led sified as ornamentals, food plants, or other to a substantial drop in catches per effort useful plants, have become naturalized and (Khoo 1976). Baines (1979) argued that man­ competitive with the indigenous species in grove removal can lead to declines of 50 to some disturbed and relatively undisturbed 80% in yield of offshore fisheries. sites on Nauru. Mangrove and coastal strand forests stabi­ lize tidal-zone soils and reduce the impact of storm surge and ocean salt spray, while damage from wind, erosion, and flood are ECOLOGICAL AND CULTURAL UTILITY OF increased when forests are removed. After EXISTING FLORAS Tropical Cyclone Isaac in Tonga in 1982, most Although highly disturbed, outnumbered, indigenous plant species were little affected by and, in some ways, "enriched" by introduced hurricane-force winds and 2- to 3-m storm exotics, the vegetation and floras of Nauru surge, whereas introduced noncoastal species and the Gilberts still constitute a critical suffered high mortality due to windfall and ecological and cultural resource to both Nau­ excessive salinity related to both storm surge ru and Kiribati. This is particularly true for and severe salt spray. Moreover, areas inland the indigenous species, virtually all of which from where coastal and mangrove forests had wide cultural utility within the subsistence were intact suffered far less damage and mor­ economy. tality (Thaman 1982). Conversely, in Truk, where mangroves were completely removed Ecological Utility by Japanese woodsmen, "the coast has been washed away rapidly and is lined with coconut The most important ecological attributes of trees in various stages of falling into the sea" coastal plant resources include the provision (Fischer and Fischer 1970). of shade and animal and plant habitats; pro­ The role of coastal plants in soil stabiliza­ tection from wind, erosion, flood, and salt tion is critical to the success of land reclama­ water incursion; land stabilization; protection tion and other low-cost coastal engineering from the desiccating effects of salt spray; and works. Species already used for land reclama­ soil improvement and mulching. tion in various areas of Asia and the Pacific Shade is important to humans, plants, and include Bruguiera gymnorhiza, Calophyllum animals, especially in highly reflective low­ inophyllum, Casuarina equisetifolia, Cocos lying coral island and lagoonal environments, nucifera, Hibiscus tiliaceus, Lumnitzera lit­ and in villages and urban areas. As popula­ torea, Rhizophora spp., Scaevola sericea, Son­ tions increase, shade and the role that trees neratia alba, Terminalia catappa, and Tourne­ and other coastal plants playas habitats for fortia argentea (Yao 1986). Many ofthe coast­ other important animal and plant species will al herbs, grasses, sedges, vines, and shrubs are become more important. Ofparticular impor­ also of considerable importance for coastal tance are mangrove ecosystems, which con­ stabilization and land reclamation. In the tribute either directly or indirectly, through Gilberts, species of particular importance for primary and secondary productivity, to the the stabilization of the extensive reclaimed Vegetation of Nauru and the Gilbert Islands-THAMAN lSI

Temaiku milkfish ponds on Tarawa are Scae­ and Sida faliax are applied in pandanus bas­ vola sericea and Tournefortia argentea. kets, along with other leaves and topsoil, as One of the most important ecological roles part ofan elaborate mulching system for giant played by coastal plants is the protection of swamp taro (Cyrtosperma chamissonis), pan­ inland agricultural areas, noncoastal vegeta­ danus, and breadfruit. Sidafaliax, in particu­ tion and fauna, settlements, and water sup­ lar, is conSidered to be such a strong fertilizer plies from salt water spray and storm surge. Of that it is only occasionally added fresh to the particular value are plants with high tolerance soil in fear of injuring plants. Other species to salt spray and saline soils. These include commonly used for mulching include Abutilon coconut, pandanus, Tournefortia argentea, spp., Boerhavia spp., Erythrina variegata, Scaevola sericea, and Guettarda speciosa, fol­ Hernandia nymphaeaefolia, Hibiscus tiliaceus, lowed in importance by Cordia subcordata, Morinda citrifolia, Scaevola sericea, Thespesia Clerodendrum inerme, Terminalia samoensis, populnea, Triumfetta procumbens, and Wol­ Premna serratifolia, Morinda citrifolia, and lastonia biflora. Coconut and pandanus ref­ Calophylium inophylium (Soucie 1983). Farm­ use, especially coconut husks, are commonly ers throughout the Pacific purposely leave heaped around the bases of plants, often strand or mangrove forests intact seaside of within small fences, to aid the mulching pro­ their gardens, as they know that to remove cess (Small 1972, Lambert 1982, Soucie 1983, these trees would make farming problematic. Thaman 1984). In the Gilberts, stands of Pemphis acidula are left seaward of agricultural areas to provide Cultural Utility protection from salt spray, and Casuarina equisetifolia has been planted to protect newly Because island societies have been perhaps planted coconuts (Thaman 1990b). Species the most dominant factor in the ecology ofthe commonly used for living fences or hedging smaller Pacific islands, the cultural utility of include Clerodendrum inerme, Cocos nucifera, plants continues to be a major factor in the Erythrina variegata, Ficus tinctoria, Hibiscus propensity of small island societies to pro­ tiliaceus, and Premna serratifolia. Crinum tect or degrade their vegetation. Ethnobo­ asiaticum is commonly used for garden bor­ tanical studies indicate that there are some 68 ders. Low-growing Hibiscus tiliaceus cultivars different uses in the Pacific islands for the 142 are planted as windbreaks, and plant products common coastal species listed in Table 2, with such as woven coconut leaves or roots are the total number of uses being 992 (Thaman used for sandscreens. 1989a, 1990b). This is an average of 7.0 uses Soil improvement and the provision of per plant, ranging from no reported uses for organic material is also important to the only four species to as many as 121 for the success of agriculture in nutritionally poor coconut. Next in order ofimportance, all with and highly permeable coastal soils, particular­ more than 15 reported uses, are Hibiscus ly atoll soils, which are among the least fertile tiliaceus, Pandanus tectorius, Calophylium in the world. As stressed by Soucie (1983), inophylium, Cordia subcordata, Guettarda organic material increases soil water-holding speciosa, Scaevola sericea, Thespesia popul­ capacity and reduces soil pH to more favor­ nea, Pemphis acidula, Rhizophora spp., able levels at which minerals become more Casuarina equisetifolia, Terminalia catappa, available to plants. Organic matter also re­ Premna serratifolia, Erythrina variegata, Ino­ duces runoff, water and wind erosion, and carpus fagifer, Ficus prolixa, Tournefortia ar­ water loss to evaporation. gentea, Morinda citrifolia, Lumnitzera litto­ Many Pacific societies have evolved sophis­ rea, Ficus tinctoria, Pisonia grandis, and ticated systems of fertilization and mulching Bruguiera gymnorhiza. Other species with at using the leaves of coastal plants. In the least seven uses each include Hernandia nym­ Gilberts, where the practice has perhaps at­ phaeaefolia, Barringtonia asiatica, Gardenia tained its greatest sophistication, the leaves of taitensis, Sida faliax, Vitex spp., Entada Guettarda speciosa, Tournefortia argentea, phaseoloides, Dodonaea viscosa, Cerbera 152 PACIFIC SCIENCE, Volume 46, April 1992 manghas, Tacca leontopetaloides, Cleroden­ TABLE 3 drum inerme, Crinum asiaticum, Triumfetta COASTAL PLANT SPECIES OF PARTICULAR CULTURAL procumbens, Cassytha filiformis, Polypodium UTILITY BASED ON A STUDY OF THE ETHNOBOTANY OF scolopendria, Neisosperma oppositifolia, and THE 142 COMMON COASTAL SPECIES IN TABLE 2 Ipomoea pes-caprae (Table 3). All of these species are found on Nauru and/or the Gil­ LATIN NAME USES berts. Moreover, these totals do not include Cocos nucifera 121 more strictly ecological functions of coastal Hibiscus tiliaceus 56 plants, such as shade; protection from wind, Pandanus tectorius 48 sand, and salt spray; erosion and flood con­ Calophyllum inophyllum 42 trol; coastal reclamation; animal and plant Cordia subcordata 37 Guettarda speciosa 33 habitats; and soil improvement (mentioned Scaevola sericea 30 previously). Pemphis acidula 27 With specific reference to Nauru and the Thespesia populnea 26 Gilberts, preliminary analyses of available Rhizophora spp. 24 Casuarina equisetifolia 22 data indicate 133 uses for 36 indigenous spe­ Premna serratifolia 22 cies and 118 uses for 41 exotic species on Morinda citrifolia 21 Nauru, and 170 uses for 29 indigenous species Ficus prolixa 20 and 104 uses for 39 exotic species in the TourneJortia argentea 20 Gilberts. This gives totals of251 and 274 uses Terminalia catappa 19 Erythrina variegata 19 for 77 and 68 species, respectively, for Nauru Ficus tinctoria 19 and the Gilberts, a clear indication of the Inocarpus Jagifer 18 cultural utility of both floras. Pipturus argenteus 18 It must be stressed that the analyses are Lumnitzera littorea 17 Pisonia grandis 17 based on traditional uses, many ofwhich have Bruguiera gymnorhiza 15 lapsed or are only employed in emergency, Hernandia nymphaeaeJolia 15 because modern technology has preempted NypaJruticans 14 them. Modern medicine, clothing, fishing Barringtonia asiatica 13 lines, matches, crockery, plastic bags, soap, Intsia bijuga 13 Cycas circinalis 13 and emergency food rations (food aid) have, Gardenia taitensis 11 for example, replaced traditional plant-de­ SidaJallax 11 rived products. Moreover, many of the cur­ Santalum spp. 10 rent generation, schooled in the modern edu­ Mammea odorata 10 Vitex spp. 10 cational system and living in the cash econo­ Entada phaseoloides 10 my, often know few of the traditional uses of Dodonea viscosa 10 plants, let alone their vernacular names-a Cerbera manghas 10 state that could be referred to as "devegeta­ Tacca leontopetaloides 9 tion ofthe mind"-and that has undoubtedly Clerodendrum inerme 9 Crinum asiaticum 9 contributed to the degradation of the indige­ TriumJetta procumbens 9 nous and long-established aboriginal vegeta­ Ficus obliqua 8 tion of both Nauru and Kiribati. Cassytha./iliformis 8 Of particular note is the importance of Polypodium scolopendria 8 Neisosperma oppositifolia 8 traditional food and beverage crops, the Metroxylon spp. 7 abandonment of which, for highly processed Ipomoea pes-caprae 7 and imported foods such as sugar, white rice and flour, cabin biscuits, noodles, canned fish, SOURCES: Adapted from Thaman 1989b, 1990b. soft drinks, alcohol, and tea, has led to dan­ gerous levels offood dependency and some of the highest, or most rapidly increasing, inci­ dences in the world of vitamin and mineral deficiency and nutrition-related diseases. Dis- Vegetation of Nauru and the Gilbert Islands-THAMAN 153 eases such as iron-deficiency anemia, night the coconut palm but also because the natives blindness induced by vitamin A deficiency, do not care to preserve or propagate them.... diabetes, cardiovascular disease, hypertension In some islands even valuable trees such as the and stroke, gout and hyperuricemia, some pandanus may be disappearing, as they are forms of cancer, and dental disease, which considered of minor importance in compari­ were rarely encountered in the past, are now son with the commercial value ofcopra." serious causes of morbidity and mortality in The highly disturbed nature of inhabited Nauru, Kiribati, and among other atoll popu­ atoll vegetation is further supported by Fos­ lations, such as Tokelauans, Marshall Is­ berg's (1988) study of Bikini Atoll, where he landers, and people from the atolls of the suggested that: "Nothing is known with cer­ northern Cook Islands, who have adopted tainty of the vegetation of Bikini prior to the western diets and life styles (Zimmet et al. coming of the Marshallese people." He ar­ 1977,1978, Speake et al. 1979, Thaman 1983, gued that, as a result of both centuries of 1985, 1988b, Coyne 1984, Pargeter et al. habitation by the Marshallese and the expan­ 1984). sion of coconut plantations under German and Japanese occupation, most of the native vegetation, which was probably "part woody­ CONCLUSIONS forest or scrub, with grass on very poor or dry The vegetation types and floras of Nauru sites," has disappeared, "though all or most and the Gilbert Islands are among the most ofthe native plant species probably survived." impoverished, degraded, disturbed, and dis­ I have stressed (l989b, 1990b) that "agrode­ placed in the Pacific islands. Long habitation; forestation" (i.e., the destruction of, or failure almost a century ofopen-cast phosphate min­ to replant or protect, a wide range ofecologi­ ing; continuous bombing, destruction, and cally and culturally valuable indigenous and displacement ofthe people during World War exotic trees in existing agricultural areas) has II; rapid urbanization; and the abandonment resulted from official overemphasis on the of agriculture and subsistence activities on expansion of monocultural cash crops for Nauru have arguably produced one of the export. The destruction of natural vegetation most severely modified natural and cultural associations and culturally valuable plants in floras on earth. In the Gilberts, limited land the Gilberts and elsewhere in the Pacific has area and habitat diversity, a long settlement been the result of this ongoing process. As history, some destruction and plant introduc­ Chambers (1983) argued, trees and tree plant­ tion during the war, rapid urbanization (by ing as traditional components of agricultural the late 1990s South Tarawa will have popula­ systems have been ignored in institutionalized tion densities approaching those of Singa­ rural development because they "fall into the pore; Carter 1984), and over a century of the gaps" between the traditional sectoral re­ monocultural expansion of coconut planta­ sponsibilities of"agriculture" and "forestry." tions onto almost all available land has also Although both the vegetation and limited produced one of the most highly modified indigenous floras of Nauru and the Gilberts floras in the world. As argued by Catala have been severely degraded and outnum­ (1957: 79) about the Gilberts: "With the ex­ bered by exotic species, most of the native ception of Pemphis stands and, of course, of species are still present, commonly in an the mangrove proper, no primitive vegetation endangered state. The indigenous flora also types can be recognized today. The original still dominates most habitats, including the formations have been so thoroughly modified later stages of the phosphate-mined pit and by man that there is no trace left of them, pinnacle topography of Nauru. Even in especially as all these islands are rather dense­ ruderal habitats and in houseyard gardens ly populated.... In many cases the primary and villages, where they are outnumbered by components are now only represented by exotics, indigenous species constitute impor­ isolated specimens, which tend to disappear tant components. not only because ofthe growing prevalence of It is argued that, while floristic degradation 154 PACIFIC SCIENCE, Volume 46, April 1992

in both Nauru and the Gilbert Islands appears could be implemented now by governments, to be among the most severe in the Pacific, the aid agencies, community organizations, and current floras of both areas still constitute families and individuals themselves. These important ecological and cultural resources strategies, which could also address many of that must be protected. Unfortunately, de­ the commonly held development objectives of spite the undeniable developmental impor­ Pacific governments, include the following: tance of vegetation protection and reforesta­ tion and agroforestry to small island com­ 1. Establishment ofprotected areas on small munities, few if any planners or national offshore islands and in coastal areas that development plans have included such mea­ could serve as buffer zones to protect sures in their lists of priorities or strategies, inland areas, renewable sources of prod­ although some countries do have legislation ucts of both subsistence and commercial (often not enforced) protecting mangroves value, and gene pools ofspecies for coast­ and coastal zones from indiscriminate exploi­ al revegetation and agroforestry. tation. 2. Establishment of nurseries at national, The importance of indigenous and long­ island, and community levels to supply established vegetation and floras to sustain­ planting materials for revegetation pro­ able island development, though often well grams and to protect currently endan­ understood by rural Pacific peoples, seems to gered coastal species ofparticular ecolog­ be poorly understood by most planners and ical and cultural importance. policymakers. The lack of quantitative data 3. Import or reintroduce, from other analo­ available to decisionmakers on the extent, gous habitats, appropriate species that nature, and cultural and ecological impor­ are absent or endangered (this assumes tance ofcoastal plant communities is a major that the causes of endangerment will be problem. However, because of recent initia­ addressed and corrected to ensure success tives to promote sustainable development, of such programs). increasing interest has been shown by some 4. Systematically protect and replant species policymakers, city planners, and administra­ of particular importance: (a) as animal tors in the protection ofmangroves and coast­ habitats, fish breeding grounds, and as al forests. This has taken the form of protec­ components in marine and terrestrial tive legislation and a number ofstudies stress­ food chains; (b) in erosion, wind, flood, ing the importance ofcoastal ecosystems and and salinity control; and (c) for soil im­ plant communities in national development provement and mulching. (e.g., Dahl 1980, Maragos et al. 1983, Hamil­ 5. Initiate coastal reclamation programs us­ ton and Snedaker 1984, Watling 1985). In Fiji, ing local materials, such as rock, sand, the establishment of a Mangrove Manage­ nontoxic domestic waste, and plant prod­ ment Committee and a survey of mangrove ucts (e.g., senile coconut palm stems) to resources have provided a basis for a pro­ build dikes, seawalls, and other engi­ posed mangrove management plan. The in­ neering structures that could be stabilized creasing activity by the South Pacific Re­ by planting appropriate salt-tolerant gional Environment Programme (SPREP), coastal species. the South Pacific Action Committee for Hu­ 6. Promote mangrove replanting and rota­ man Ecology and Environment (SPACHEE), tional utilization schemes, such as those and an increasing number ofenvironmentally currently fostered in Southeast Asia (Yao conscious ministries and environmental man­ 1986, Chan 1987). agement committees throughout the region 7. Encourage the protection or planting of augur well for the future. buffer zones and salt-tolerant and wind­ To encourage vegetation protection, re­ resistant living fences, hedging, and wind­ vegetation, and reforestation ofsmall islands, breaks in agricultural, residential, and there are at least ten action strategies that urban areas, and along transportation Vegetation of Nauru and the Gilbert Islands-THAMAN 155

routes and causeways, which are often ment in the ASEAN region. Trop. Coastal subject to erosion and damage during Areas Manage. 2(3): 6-8. extreme events. CHRISTOPHERSEN, E. 1927. Vegetation of 8. Encourage home gardeners; institutions Pacific equatorial islands. Bull. Bernice P. such as schools, hospitals, prisons, police, Bishop Mus. 44. and military institutions; government de­ COYNE, T. 1984. The effect of urbanization partments; private businesses; and com­ and western diet on the health of Pacific munity-based organizations to become island populations. South Pac. Comm. actively involved in revegetation pro­ Tech. Pap. 186. grams, both at the national and commu­ DAHL, A. L. 1980. Regional ecosystems sur­ nity levels. vey of the south Pacific area. South Pac. 9. Encourage aid agencies, particularly non­ Comm. Tech. Pap. 179. government organizations, to support na­ DOUGLAS, N., and N. DOUGLAS. 1989. Pacific tional-level and community-based pro­ islands yearbook, 16th ed. Angus and grams of coastal revegetation and tree Robertson, Australia. planting because of their considerable FISCHER, J. S., and A. M. FISCHER. 1970. The developmental potential and ecological Eastern Carolines. Human Relations Areas importance. Files Press, New Haven, Connecticut. 10. Make the consideration ofthe protection FOSBERG, F. R. 1952. Vegetation of central and/or replanting of salt- and wind-resis­ Pacific atolls, a brief summary. Atoll Res. tant coastal tree and plant species integral Bull. 23: 1-25. components of all coastal development ---. 1960. The vegetation of Micronesia. projects, and a major item of focus in the Bull. Am. Mus. Nat. Hist. 119(1): 1-75. process of environmental impact assess­ ---. 1965. The island ecosystem. Pages ment (EIA). 1-6 in F. R. Fosberg, ed. Man's place in the island ecosystem: A symposium. Bernice P. Through such actions it should be possible Bishop Museum Press, Honolulu. to protect and enhance the vegetation and ---.1969. Plants ofSatawal Island, Caro­ floras so crucial to the ecological integrity and line Islands. Atoll. Res. Bull. 132: 1-13. cultural survival of small-island societies, ---. 1972. Phytogeography of Micro­ such those of Nauru and the Gilbert Islands. nesian mangroves. Smithsonian Institu­ tion, Washington, D.C. ---. 1988. Vegetation of Bikini Atoll. LITERATURE CITED Atoll Res. Bull. 315: 1-28. FOSBERG, F. R, and M. EVANS. 1969. A ALKIRE, W. H. 1974. Numbers ofplant, insect collection of plants from Fais, Caroline and land bird species on nineteen remote Islands. Atoll Res. Bull. 133: 1-15. islands in the southern hemisphere. J. Linn. FOSBERG, F. R., D. OTOBED, M.-H. SACHET, Soc. BioI. 6: 143-152. R L. OLIVER, D. A. POWELL, and J. E. BELLWOOD, P. 1978. Man's conquest of the CANFIELD. 1980. Vascular plants in Palau. Pacific: The prehistory of southeast Asia Department of Botany, Smithsonian Insti­ and Oceania. William Collins, Auckland. tution, Washington, D.C. CARTER, J., ed. 1984. Pacific islands yearbook, FOSBERG, F. R., G. PAULAY, T. SPENCER, and 15th ed. Pacific Publications, Sydney. R. OLIVER. 1989. New collection and notes CATALA, R. L. A. 1957. Report on the Gilbert on the plants ofHenderson, Pitcairn, Oeno, Islands: Some aspects of human ecology. and Ducie islands. Atoll Res. Bull. 329: Atoll Res. Bull. 59: 1-187. 1-18. CHAMBERS, R 1983. Rural development. FOSBERG, F. R, and M.-H. SACHET. 1987. Longmans, London. Flora of the Gilberts, checklist. Atoll Res. CHAN, H. 1987. Mangrove forest manage- Bull. 29: 1-30. 156 PACIFIC SCIENCE, Volume 46, April 1992

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