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Of all non-urban, Pacific Island agroforestry systems, those on atolls operate under the most severe environmental constraints and greatest population pressures. Further, in response to these constraints and pressures, atoll-dwellers have created the most intensive agroforestry in all the Pacific, with the greatest relative dominance of trees over non-trees.
Tarawa and Abemama, two of the islands of the Gilberts group of Kiribati, provide excellent examples of atoll agroforestry and will serve here as casestudies of village-level agroforestry wherein a wide range of cultivated and protected wild trees and a more limited number of non-tree plants and livestock are raised within a relatively dense matrix of coconut palms. The descriptions are based on a 10 day reconnaissance survey of agroforestry on Tarawa and Abemama in 1984, subsequent visits in 1989 and 1991, and a survey of the available literature.
Population pressure on land in Kiribati is high, most particularly on the main atoll of Tarawa, where it is projected that by 1993 (with a high annual growth rate of 4.3 per cent because of migration from the outer islands) there will be a population of over 34,000 people living on only 920 ha (Douglas and Douglas 1989, 282). Population densities on Abemama and other outer islands are significantly lower. The only agricultural export from Kiribati and the mainstay of the export trade is copra, which was worth Australian $3.1 million in 1989 (Forum Secretariat 1991).
The atolls and table-reef islands of Kiribati rarely rise more than 3 metres above high-tide level, with the true atolls surrounding large central lagoons. The highly alkaline, calcareous, and rocky soils are among the most infertile on earth, with very low water-holding capacity, little organic material, few available soil macro- and micro nutrients, apart from calcium, sodium, and magnesium, and restricted availability of iron and other micronutrients because of the high pH. Rainfall is extremely variable, with extended periods of drought being common. Groundwater is brackish to slightly salty and subject to salt-water incursion. The islands, where one is never more than 0.5 km from the sea, are susceptible to inundation by storm surge and tsunamis and the constant effect of humid salt-spray-laden winds. As Small (1972, 5) said in his book on atoll agriculture: "all this adds up to a very difficult environment for plants, and produces problems for animals and man."
Agroforestry resources
Because of the small size of the islands of Kiribati and their isolation, geological youth, and harsh environment, indigenous plant species number only 66, none of them endemic. There are just under 300 species, including exotics, mostly ornamentals and weeds, that have ever been reported to grow there (Fosberg and Sachet 1987; Fosberg et al. 1979; 1982; Thaman 1989b).
It is under these harsh conditions and with a paucity of flora to choose from that the I-Kiribati (people of Kiribati) have evolved their distinctive agroforestry system, which incorporates into a matrix of the superdominant coconut palm:
Coconut palms
Almost all coconut palms seem to have been planted, either deliberately or accidentally, by the I-Kiribati. The resultant agroforested landscape takes the form of a natural forest, rather than an orderly plantation, because a great proportion of the trees are spontaneous occurrences of different heights and ages, rather than equally-spaced trees of the same age. On both the seaward and lagoon sides, coconuts lean outward interspersed with pan-tropical strand species, whereas in the higher central portions of the islands they generally form thick stands, with young coconut seedlings and other plants in various stages of growth often forming an almost impenetrable jungle. In many areas, plants suffer from excessive density, although towards the lagoon side, where most of the settlements and giant taro (babai) pits are found, the trees begin to thin out (Catala 1957, 22; Watters and Banibati 1977, 33). Moul (1957, 1), however, found concentrations to be denser along lagoon shores on Onotoa atoll in southern Kiribati.
Sixteen locally recognized coconut cultivars are divided into two main categories according to whether the mesosperm is edible (te bunia) or non-edible (te ni), the latter term also applying to coconuts in general. Some are favoured for their juicy flesh, the quality and sweetness of their toddy, and some for the quality of their fronds, coir from the husk, or wood for use as handicrafts and building materials (Catala 1957, 25-27).
Catala (1957, 30-34) stressed the "extraordinary resistance of the palm" in Kiribati to prolonged drought and its ability to continue to produce inflorescences, which although incapable of producing commercial-grade copra, still produced the nutritionally essential toddy. The ability to withstand prolonged drought depends on the nature of soils, the degree of salinity of groundwater, the nature of tides during droughts, and the sporadic occurrence of fire during drought periods. Despite this resistance to drought and increasing salinity, the production of most palms, particularly of copra, is severely affected by drought, although palms around village sites, beside babai pits or in abandoned babai pits, and around inland ponds seem to be affected only minimally by drought because of proximity to the freshwater lens or the presence of greater domestic and organic waste near villages and babai pits. Watters and Banibati (1977, 33) reported that, after a prolonged drought in the early 1970s, only 44.2 per cent of mature coconut palms surveyed on Abemama were bearing in 1972.
A transect across Bikenibeu islet, Tarawa, contained 138 irregularly spaced palms in an area of 5,950 sq m, a very high density of 231 per ha - compared with a density of only 157 per ha on a fully stocked regularly spaced copra plantation in Tonga. In this same area, 11 pandanus trees, most of them concentrated in the mid-island portion or toward the lagoon and village end of the transect, were also inventoried. Nearer to village sites, the density was considerably lower, with 14 surveys giving an average density of only 155 palms per ha, not counting other important trees. For example, one village, covering an area of some 10,750 sq m, had only 100 coconuts, a density of 93 per ha, as well as 36 breadfruit trees. For village areas, the average density ranged from 80 to 150, whereas densities were from 200 to 350 in bush garden areas.
Watters and Banibati (1977, 35) suggested that the density of coconut palms on rural Abemama was 321 palms per ha, with densities of bearing palms being 151.8 (given a figure of 47.3 per cent bearing palms). They estimated annual nut production per bearing tree at 17.8, a figure somewhat lower than Catala's (1957) earlier estimate of 23.1 nuts per year on Tarawa, possibly because the Abemama survey was conducted after an extended drought. Coconut palms provide not only the single agricultural export possibility of copra but also oil, drink, and food for both people and pigs.
For toddy (karewe) production, which perhaps nowhere has such fundamental importance as in the harsh environment of Kiribati, the flower spathes of selected trees are cut and bound and tapped twice a day, once in the morning and once in the afternoon, yielding approximately two coconut shells of liquid per day. A dietary staple for most I-Kiribati households, especially in times of severe drought when palms produce few fruit, fresh toddy is drunk daily by most I-Kiribati. Toddy is also fermented to make a vitamin B-rich (one-third the level found in brewer's yeast) drink of varying alcoholic content, a boiled-down syrup, which can be kept without fermenting, and a solid caramelized form (Catala 1957, 44-46).
Particularly in rural areas, coconut flesh is the major source of dietary fat and energy, as well as contributing some iron, fibre, and other nutrients, and is prepared and consumed in countless ways. Toddy is particularly rich in energy and vitamin C and has significant amounts of vitamin B and iron (Pargeter et al. 1984, 10-15). Bayliss-Smith's (1982, 62) study of Ontong Java atoll in the Solomon Islands stresses the dietary importance of coconut, which contributed 21 per cent of all food energy directly, as well as the copra, which provided the cash to purchase another 25 per cent of the total food energy consumed. In addition to its critical dietary importance, the coconut palm is used in a myriad of other ways to produce products of economic and cultural importance, the imported substitutes for which would either be too costly or unobtainable for most I-Kiribati.
Pandanus
After the coconut, the pandanus, or te kaina (Pandanus tectorius), is the most important tree of Kiribati agroforestry systems, with almost 200 different recognized cultivars, many of which may be exclusive to a given village or family (Luomala 1953; Overy et al. 1982). Catala (1957, 51) reports, however, that only 16 names were widely recognized on Tarawa.
Because pandanus will grow in very poor or thin soils, it can be found growing almost anywhere on atoll islets. Catala (1957, 52) found that for Tarawa atoll there was an equal density of pandanus, whether it was on the ocean or lagoon side or in the interior, although it grew more successfully where coconut density was lower, particularly in marshy areas or along the lagoon edge, where pandanus seems to have a definite advantage over the coconut. Moul (1957) also found pandanus present in most vegetation associations on Onotoa atoll.
Although natural stands commonly occur in swampy areas, in coastal littoral forests, and in long-neglected bush plantations, the majority of pandanus in garden lands or around villages or residences are planted and owned by individuals (Luomala 1953, 83). Because pandanus propagated from seeds will rarely reproduce desired characteristics, almost all planted pandanus are started from cuttings, ideally cuttings that already bear the beginnings of adventitious roots. At times, new trees will be mulched with leaves of Guettarda speciosa or other plants, and covered with black topsoil. Frequent tamping around young plants, even after they are fully established, is carried out to obtain low, easy-to-harvest high-yielding trees. Given optimum light availability and care, trees near villages can bear as soon as 10 months after planting, whereas they may take up to more than a year in bush gardens (Catala 1957, 53-54).
The fruit of pandanus is a very important part of the I-Kiribati diet; the tree also provides raw material for a wide range of plaited ware, construction materials, medicines, decorations, parcelization, perfumes, and other uses, as well as being the I-Kiribati ancestral tree, from which, according to mythology, the progenitors of the I-Kiribati came (Luomala 1953, 83).
The fleshy parts or drupes of the ripe fruits are consumed raw, as well as being prepared or included in other dishes in a variety of ways. Some of the commonest preparations are te tangauri, te tune, and te karababa. Te tangauri, a paste made from a mixture of a puree of the fresh fruit and grated coconut, can be eaten fresh or dried in the sun. Te tuae is prepared by cooking the fruit, removing most of the fibre, and making a paste, which is then spread on leaves and dried in the sun. The dried paste, which is then cut into pieces for further desiccation, will keep for years, constituting a food reserve that can be used on long voyages or prepared at a later time by softening in and/or prepared with coconut milk or grated coconut. Te karababa is prepared by cooking the drupes, then mashing and mixing them with grated coconut. This mixture is then dried and eaten or is further processed, by toasting and grinding into flour, into te kabubu, which keeps for long periods and which may be eaten straight or as an ingredient in a range of dishes, for example, toddy molasses (Catala 1957, 56-58).
Pandanus leaves are used in the production of thatching, roofing, a range of fine and everyday mats, hats, sails (in the past), cigarette wrappings, food wrappers, caulking material, and baskets for babai compost. The trunk and adventitious roots are used in house and in general construction, with particular cultivars being best for different uses (Catala 1957; Luomala 1953; Overy et al. 1982).
Breadfruit
The next most important cultivated plant is the breadfruit, of which there are two distinct species, the common breadfruit (Artocarpus altilis) and the Mariannas breadfruit (A. mariannensis), plus a hybrid of the two (Fosberg et al. 1979; Fosberg and Sachet 1987; Thaman 1989b). Although well-adapted to the atoll environment, its distribution seems to be directly related to the salinity of groundwater, being planted primarily in villages or their immediate vicinity, and occasionally along roadsides, particularly on the more protected lagoon side of the islands. Moul (1957, 11) reported that it was very common along village streets on Onotoa, and the canopy of one of the most extensive breadfruit groves on Tarawa almost covers the main road through the chiefly village of Eita.
Although pandanus is much more common, breadfruit rivals it in subsistence importance in some areas. Whereas pandanus is an important component of the bush flora, often forming pure stands, breadfruit is rarely found in the heart of the bush (Catala 1957, 61), but forms a major, often dominant, component of the vegetation around villages such as Eita and Betio on Tarawa. In one village on Tarawa, with a population of 115 (22 families), Catala (1957, 64) counted 93 trees, all of which belonged to the person or household that planted them, even if the planter moved to another village. The number of trees per household varied from 0 to 11, with the mode being 4 (Catala 1957, table 10).
Like pandanus, breadfruit are almost always deliberately planted in holes filled with waste, including the dead leaves of coconut and breadfruit and the leaves of te mao (Scaevola sericea), te ren (Tournefortia argentea), te uri (Guettarda speciosa), and te non (Morinda citrifolia), and often topped with black topsoil found under Guettarda speciosa (Catala 1957, 64; Moul 1957; Small 1972). Under favourable conditions, trees may grow over 20 metres high, with trunks almost 2 metres in circumference, although under less favourable conditions, trees may only reach 8-10 metres and 1 metre in circumference (Catala 1957, 64).
Of the major economic plants, the breadfruit seems to have the least resistance to prolonged drought. Sabatier (1939, in Catala 1957, 61) says that breadfruit trees survive with difficulty in the drier southern islands and "are practically exterminated every ten years." Moul (1957, 11) reports that a significant proportion died during the prolonged drought of 1949-50.
The trees generally bear for the nine months from May to January, during which time fruit is often very abundant, being eaten ripe, both raw and cooked, depending on the variety, as well as being preserved by cooking, crushing, and drying as te kabuibui ni ma, or te tune n-te mad. Young leaves of breadfruit are used medicinally to cure ear infections, and buds are used for conjunctivitis; mature leaves provide wrapping for food and serve as fertilizer or compost for babai and other plants; the wood can be made into outrigger canoe hulls and fishing floats (Catala 1957, 65-66).
Other cultivated fruit-trees
Other commonly cultivated fruit-trees are papaya, banana and plantain cultivars, the native fig, or te bero (Ficus tinctoria), the common fig, or te biku (Ficus carica), and the lime (Citrus aurantiifolia). Occasionally lemon trees (Citrus limon) are found, and guava and mango have been introduced but are rare, and, in the case of mango, survive with difficulty.
Papayas are particularly common in villages and, where well cared for and mulched, are healthy and produce good fruit that is eaten raw when ripe, especially by children, and cooked green with coconut milk. In a village of 23 households, with a population of 115, Catala (1957, table 10) found 111 papayas, amounting to just under one tree per person.
Banana and plantain cultivars are occasional to common on Tarawa and Abemama and much more common on wetter islands in north Kiribati, such as Makin and Butaritari, and in southern Tuvalu, where the main island of Funafuti (meaning the "place of the banana") is renowned for its extensive banana plantings. Bananas are commonly grown around houses in villages and occasionally planted in abandoned banai pits or in specially dug banana pits, a common practice at mission settlements and boarding schools. When grown in pits, bananas and plantains are normally not planted in flooded soil, as is babai, but in slightly higher parts of pits or in pits that have been partially filled.
Where well looked after, bananas grow well and are a favoured staple. If grown as a "pit plantation," it is usually necessary to dig a rather deep trench around the pit to keep coconut roots out. A layer of dark soil collected from under Guettarda and Scaevola is added along with composting and rusted tin cans to provide iron (Catala 1957; Small 1972). Although there seems to be considerable scope for an expansion of banana and plantain pit cultivation, the taro beetle (Papuana sp.) may have caused widespread damage to plants grown in pit plantations. When grown in villages, close to the lagoon side, mulching with organic material, coconut husks in particular, results in good yields.
The native fig, or te bero (Ficus tinctoria), is commonly cultivated around villages and occasionally in plantation areas. Moul (1957, 12) reported it as common around abandoned babai pits and present in small thickets in rich soils around Pisonia grandis groves on Onotoa atoll in southern Kiribati. It is propagated vegetatively by planting branch cuttings, and its fruits are an important staple in the drier southern islands. The fruits are picked when ripe and sometimes when green, cooked, crushed in a mortar into a puree that can be eaten after being sweetened with toddy molasses (kamaimai) or sugar and grated coconut or preserved by drying in the sun on Guettarda speciosa leaves. Fig trees reportedly bear many times throughout the year, and have wide cultural utility (Catala 1957; Luomala 1953; Small 1972).
The common fig, reportedly introduced by missionaries, seems to be very well adapted to the atoll environment and is occasionally found propagated by cuttings in village home gardens.
The lime (Citrus aurantiifolia) is by far the most common citrus fruit grown in Kiribati, but is found only occasionally in villages. The fruit is highly sought after for squeezing on fish and other foods and for making drinks. Lemon trees are present on the agricultural experiment farm at Bikenibeu, but are rare elsewhere.
Other cultivated food plants
Other cultivated but minor tree-like food plants include sugar cane (Saccharum officinarum) and hibiscus spinach (Hibiscus manihot), both of which are found occasionally in villages around homes. Although sugar cane grows poorly in some localities, it shows promise where well-mulched. Hibiscus spinach, a very nutritious green vegetable, reportedly introduced by contract workers returning from the phosphate mines on Banaba (Ocean Island), grows particularly well and shows little or no evidence of the insect or disease damage so characteristic in Fiji.
Giant swamp taro
The major understorey food plant in Kiribati is the ceremonially important staple, giant swamp taro, or te babai (Cyrtosperma chamissonis), which is cultivated in pits excavated to the freshwater lens, and is heavily mulched. About 20 named cultivars are recognized (Small 1982). Te babai is not a woody species, but because of the very sophisticated system of mulching and fertilization with leaves from numerous tree species, and because the babai pits are found within a matrix of coconut palms and other trees, te babai is an integral component of the Kiribati agroforestry system.
Te babai was probably more extensively cultivated in the past, as evidenced by the numerous abandoned pits, some of which have been overrun with coconut seedlings and weeds. Although pits are often abandoned as the water becomes more brackish, many were obviously abandoned long ago, with most pits being ancient, the inhabitants having no recollection of their origin (Catala 1957, 68). On Abemama, for example, Watters and Banibati (1977,37) found, in a survey of 16 households, that whereas the mean number of pits in use was only 4.2, the mean number of empty pits per household was 23.4, with only 7.7 still containing the water necessary to produce te babai. Moreover, few of the productive pits were fully stocked, thus "reflecting more basically the changing food preferences and habits and growing reliance on the cash component of a household's total income" (Watters and Banibati 1977, 38). On Onotoa, Moul (1957, 5) found that as many as 10 individuals had separate plots in single pits ranging from 25 to 30 feet long and from 10 to 20 feet wide.
As a result, te babai has become almost a luxury in many areas, reserved almost exclusively for ceremonial purposes, rather than constituting a staple food (Catala 1957, 67). Nevertheless, te babai cultivation continues to be surrounded with tradition, and there has been some recent rehabilitation of abandoned pits on both Tarawa and Abemama. As Catala (1957, 67) relates: "pulling up a babai in order to offer the tuber to a distinguished guest is considered the greatest honour that can be paid to him."
Te babai pits must be excavated through as much as 1.5 metres of hard conglomerate and limestone to reach the freshwater lens, with Moul (1957, 5) reporting pits up to 15 feet deep. The young shoots are planted in holes about 0.3 metres (2 feet) deep in the bottom of the pit and mulched and fertilized with black topsoil from stands of Guettarda speciosa, Scaevola sericea, and other plants and a variety of leaves, some of which are specially prepared for the purpose, using techniques generally not divulged. Baskets of pandanus or coconut leaves are commonly made, into which the shoot is planted or in which the fertilizer or mulch is administered to the plants in the pit.
Leaves used for fertilization and mulching, in order of importance, are te kaura (Sida fallax), te uri (Guettarda speciosa), te ren (Tournefortia argentea), te mad, or breadfruit (Artocarpus spp.), te woo (Boerhavia repens) and, to a lesser extent, species such as te kaura ni Banaba (Wollastonia biflora), te kanawa (Cordia subcordata), te kiaou (Triumfetta procumbens), and te kiaiai or te rao (Hibiscus tiliaceus). These leaves, with the exception of Sida fallax, are mixed with other plant waste, particularly old pandanus leaves and coconut refuse, black topsoil, and occasionally ground pumice (te uuan), and applied green or dried to the basket surrounding the plant or placed in the pit near the plant. Because the leaves of a variety of trees and the black topsoil found under trees are very important in te babai cultivation, increasing agrodeforestation may be, at least in part, responsible for the decline in its cultivation in Kiribati.
Cultivated exotic timber trees
Two trees deliberately introduced for reforestation purposes are Casuarina equisetifolia and Leucaena leucocephala. Casuarina, in particular, which was rare in the 1950s, has been widely planted on Tarawa as part of government-sponsored reforestation programmes to provide wind-breaks for recently planted coconut palms on the ocean sides of atoll islets (Overy et al. 1982, 14) and to provide firewood. Leucaena was also introduced for reforestation purposes, because of its nitrogen-fixing ability, but is not widely planted.
Cultivated ornamentals
Commonly cultivated ornamentals, most of which are found in home gardens, mission settlements, school grounds, or in major settlements, include plumeria, or frangipani (Plumeria rubra and P. obtusa), hedge panax (Polyscias guilfoylei and P. fruticosa), copperleaf, Jacob's coat, or the beefsteak plant (Acalypha amentacea), false eranthemum (Pseuderanthemum carruthersii), golden bells (Tecoma stans), bougainvillea (Bougainvillea spp.), Lantana camara, Hibiscus rosa-sinensis, dracaena (Dracaena fragrans), ixora (Ixora casei), and the poinciana, or flame tree (Delonix regia). Also present in home gardens, but not common, are the Tahitian gardenia (Gardenia taitensis), Acacia farnesiana, Cordyline fruticosa, and the Pacific fan palm, Pritchardia pacifica. With the possible exceptions of Dracaena fragrans and Pritchardia pacifica, all of these plants constitute important sources of flowers and leaves, which are used - along with flowers from native species such as Guettarda speciosa, Sida fallax, and Scaevola sericea - in the ubiquitous leis and head garlands so important for all social and ceremonial occasions.
Important indigenous species
Important indigenous trees or tree-like species, which are integral and widespread components of the Kiribati agroforestry system, include Scaevola sericea, Guettarda speciosa, Tournefortia argentea, Sida fallax, Morinda citrifolia, Clerodendrum inerme, Premna serratifolia, Pemphis acidula, and Dodonaea viscosa. Other indigenous trees, which are uncommon to rare in agricultural areas, but are sometimes found in coastal strand forest, home gardens, and villages, and as street trees in the main settlements, include Calophyllum inophyllum, Cordia subcordata, Terminalia catappa, Pisonia grandis, Hibiscus tiliaceus, Terminalia samoensis, Barringtonia asiatica, Hernand ia nymphaeifolia, Macaranga carolinensis, and Thespesia populnea. Also of localized importance are the mangrove species Rhizophora mucronata, Bruguiera gymnorhiza, and Lumnitzera littorea. All of these species have important cultural uses, some of which are described here or in the Appendix. The information is based on field surveys and on Luomala (1953), Catala (1957), Moul (1957), and Overy et al. (1982).
Scaevola sericea is the commonest understorey shrub in Kiribati (Moul 1957, 22). It is found everywhere in coastal littoral forest and forms dense thickets. It is common in plantations, especially where coconut density is low, and occasional in home gardens and in villages and other habitats. It is an important component of the coastal strand vegetation, which provides protection from salt spray to inland plantations and gardens, is an important producer of humus and organic material because of its abundance, and has wide-ranging cultural utility.
Guettarda speciosa, Tournefortia argentea, and Sida fallax are the most common sources of leaf compost for the cultivation of babai (Cyrtosperma chamissonis). Guettarda speciosa, one of the main components of the atoll vegetation, is occasionally cultivated in village gardens and is particularly common in the centre of islets, where it is important in the formation of the black topsoil mixed with leaf compost used in planting babai, pandanus trees, and other crops. Guettarda's wood is used in general construction, its leaves in the production of garlands and head wreaths and when spreading pastes or preserves for sun-drying. The plant is prominent in I-Kiribati legends, mythology, and is associated with phases of the moon and stations of the sun - all of which uses together make it one of the most culturally important plants in Kiribati.
Tournefortia argentea is commonly found scattered in groups in plantation areas, occasionally in strips of ocean or lagoon strand forest, and was reported by Moul (1957, 20) to be very common on the edges of babai pits on Onotoa. Like Guettarda speciosa, it has wide cultural utility. Its wood was occasionally used as a substitute for Calophyllum inophyllum for canoe bows and Y-shaped pieces as spar supports on outrigger canoes. It also provides a favoured fuel, and was used as the bottom piece in making fire by friction in the past. The leaves are reportedly eaten in salads by boat crews, used medicinally to reduce fever, and as a female deodorant, and also in magic and for scenting coconut oil, as well as being an important ingredient in compost or fertilizer for babai and other plants. Te ren also features in many IKiribati legends.
Sida fallax, a small shrub found scattered throughout plantations, is occasional in villages, and common on lagoon sides and on the inner margins of coastal ramparts of islands. It is a favoured species for personal ornamentation and magic, particularly love magic, and is used medicinally. Its flowers and leaves are shredded and dried to produce the "strongest" compost or fertilizer for babai. Also occasional in plantation areas and cultivated as a living hedge or ornamental in home gardens is Clerodendrum inerme. It is reportedly used medicinally and its flowers are used in garlands.
Pemphis acidula is very common on sandy areas inland from mangroves and in clusters in garden areas bordering the ocean coast and on beach ramparts, where it often forms almost pure stands and serves as protection against sea spray. It is important medicinally, and the dense, extremely hard, wood has wide utility because of its resistance to sea water, and is a favoured firewood. Dodonaea viscosa, indigenous to many Pacific islands, but possibly a recent introduction to Kiribati, locally common near existing villages and in sites of former dwellings and occasional in garden areas, also has a variety of uses.
Morinda citrifolia and Premna serratifolia, two of the most important medicinal and magical plants in Kiribati, are occasional in coastal areas and relatively common in bush gardens and home gardens in villages. The pungent ripe fruits of M. citrifolia are occasionally eaten after boiling by old people, as a famine food, and as a stimulant on long fishing trips or ocean voyages, and the consumption of the young leaves has been actively promoted recently as a rich source of vitamin-A to combat outbreaks of vitamin A-deficiency night blindness among children.
Other indigenous species of wide cultural utility occasionally present in the coastal strand forest bordering garden areas, in home gardens, or in settlement areas include Calophyllum inophyllum, Cordia subcordata, Terminalia catappa, Pisonia grandis, Hibiscus tiliaceus, Terminalia samoensis, Barringtonia asiatica, Hernandia nymphaeifolia, Macaranga carolinensis, and Thespesia populnea. All of these culturally useful species were more widespread in the past before official government emphasis was placed on clearing indigenous species to extend and rehabilitate coconut plantations and before current high population densities placed such pressure on limited arboreal resources.
Cordia subcordata is occasional in coastal forests and in villages, its attractive wood being highly valued for woodwork, and the inner bark, leaves, and attractive orange flowers highly valued for medicine, magic, composts, and garlands. Terminalia catappa and the related species, Terminalia samoensis, both useful trees, are occasional in villages and in tree groves in plantations and inland from coastal littoral forest, almost always as individual trees, and sometimes planted as ornamentals.
Calophyllum inophyllum, so important medicinally and for general construction, canoe building, and woodworking, is occasional around villages and towns, and was a sacred tree in the past on Tabiteuea.
Pisonia grandis, the favoured nesting tree for the black noddy, an important food resource, is uncommon to occasional as isolated individuals or small groups, and has been recently planted in villages and at the hospital in Bikenibeu for its edible leaves, which are rich in vitamin A. It was probably more common in the past as a dominant in the indigenous forest. There reportedly remains a large traditional
Pisonia reserve on the island of Onotoa in south Kiribati, which is surrounded by extensive guano deposits and the most luxuriant vegetation seen on the atoll (Moul 1957, 4).
Mangroves provide a habitat and serve as an important food supply for many of the important edible fish species. They also have an important role in coastal stability, land reclamation, and the protection of gardens from salt-water spray at the interface between the lagoon and agricultural areas. On Onotoa, they reportedly encircle fish-ponds (Moul 1957, 5). Mangroves are also used in construction and in the production of medicines, dyes, and garlands. They can, consequently, be considered integral components of agroforestry systems, particularly in land-scarce areas such as Kiribati. Rhizophora mucronata is the most common species, forming very dense stands on swampy lagoon shores as well as being found on the windward ocean coast at Bairiki, Tarawa. Bruguiera gymnorhiza is common to occasional, and Lumnitzera littorea, although rare on Tarawa and possibly absent on Abemama, is reportedly more common on Butaritari.