|Agroforestry in the Pacific Islands: Systems for Sustainability (UNU, 1993, 297 pages)|
|5 Agroforestry in Polynesia|
Although the agroforestry systems of the smaller, more geologicallyrecent islands of Polynesia are in many ways similar to those of the larger, more heavily forested islands of Melanesia, there are significant differences. Little truly native forest remains in Polynesia, agricultural cycles have shortened, there are generally fewer tree species, and agrodeforestation is more widespread, both in terms of the elimination of trees and forest stands and the failure to protect or replant trees in active agricultural areas. The main causes of these processes are the comparative scarcity of land, rapid population growth on some islands, habitual burning, the increasing use of land for monocultural commercial agricultural production or non-agricultural purposes, and a loss of appreciation of the importance of trees among the younger generation. However, as the four Polynesian case-studies illustrate, great variation remains in Polynesia, with very rich agroforestry traditions present in areas such as Tonga and Rotuma, whereas at the other extreme - as in Aitutaki, in the Cook Islands agrodeforestation has proceeded to a dangerous stage.
Although similar agroforestry zones are found in Melanesia and Polynesia, very little primary or relatively undisturbed forest remains in Polynesia, and what natural forest there is has always been floristically less diverse than that in Melanesia. In Polynesia, the dominant vegetation communities consist of coastal strand and, in some cases, mangroves, isolated relict stands of tropical lowland or upland forest, mature fallow forest, highly degraded fire-climax communities rarely used for agriculture, and the much modified communities and fallow vegetation found in active agricultural areas, villages, and towns.
Shifting agroforestry remains a widespread practice in well-drained areas, with semi-permanent, sometimes irrigated, Colocasia taro gardens in poorly-drained alluvial lowlands and river valleys, and home gardens in settlements. In the complex systems of Tonga and Rotuma the dominant root-crop staples and a wide range of banana and plantain cultivars are grown in a shifting pattern on land so heavily planted with coconuts, breadfruit, citrus trees, and other trees that most garden areas resemble polycultural orchards. Interspersed throughout garden areas are small groves of secondary fallow forest or bushfallow containing both indigenous and exotic species of great cultural utility. As in the case of Melanesia, coastal strand forest, swamp forest, and mangrove forest are considered integral and useful components of the productive landscape.
Where staple and supplementary food crops continue to be partly derived from and integrated with a matrix of trees, the landscape also contains many important non-food trees or tree-like plants, for example, pandanus cultivars for handicrafts (Pandanus spp.), paper mulberry (Broussonetia papyrifera) for bark-cloth manufacture, and kava (Piper methysticum), the traditional ritual beverage of Polynesia. Most of these plants, which will be further described in the casestudies, are also important in, and probably introduced through or from, Melanesia.
An aspect of Polynesian agriculture that is not so well developed in the areas studied in Melanesia is the increasing, often intensive, monocultural commercial cultivation of non-tree crops, both for export and for the rapidly expanding local urban markets. These crops, most of which also have subsistence value, include water melons, pineapples, peanuts, tomatoes, Chinese cabbage, capsicum, cucumber, and other short-term vegetables, and traditional staples, such as yams, Colocasia and Xanthosoma taros, sweet potato, and cassava. In Tonga, vanilla (Vanilla fragrans) and butter squash (Curcurbita sp.), the latter destined for the Japanese market, have become monocultural components of the system. Vanilla is also produced for export in French Polynesia.
Bananas are grown on an intensive monocultural basis for export in Tonga, Western Samoa, and the Cook Islands, and there are attempts to develop monocultural citrus production for export and local processing in Nine and the Cook Islands. Both bananas and citrus have suffered from continuing problems with pest and disease control, damage from tropical cyclones and high winds, poor management, inadequate quality control, marketing difficulties, and import and quarantine restrictions. Consequently, these crops have been largely uneconomic, and their further development has been highly aid-dependent. The coconut remains the main cash crop for the majority of smallholder agroforesters in Polynesia, whereas the more diversified commercial arboricultures found on the large islands of Melanesia, based on the inclusion of cocoa, coffee, rubber, and oil palm, are largely absent in Polynesia, except in Samoa, where cocoa has been a major cash crop since the time of German occupation. Coffee has been widely tried, with limited production for local consumption in Tonga, Western Samoa, the Cook Islands, and French Polynesia.
Exotic species of post-European introduction that have become integral components of Polynesian agroforestry systems include kapok (Ceiba pentandra), frangipani (Plumeria rubra and P. obtusa), allspice and bay rum (Pimenta doica and P. racemosa), and jambolan (Syzygium cumin)), with leucaena (Leucaena leucocephala) and guava (Psidium gunjava) having become widely naturalized components of fallow vegetation that grow in almost impenetrable monospecific stands on many islands. There are also a number of exotic timber species introduced as part of reforestation schemes; these include Albizia falcataria, silky oak (Grevillea robusta), eucalyptus (Eucalyptus spp.), cigar box cedar (Cedrela odorata), West Indian mahogany (Swietenia macrophylla), and Caribbean pine (Pinus caribaea), which have been planted in small woodlots, as border plantings, or as scattered individual trees.
Home gardens are an important component of Polynesian agroforestry strategies, particularly in areas like Aitutaki and Rarotonga, where agrodeforestation has been extensive. Home gardens serve as refugia for endangered species, as well as avenues for the testing and introduction of new species. Home-garden agroforestry is characterized by a wide range of fruittrees, ornamental trees, and shrubs with fragrant flowers or leaves, and a number of other useful trees that serve as a matrix for lawns, structures, and scattered flower gardens.
Throughout most of Polynesia, continuing official bias toward monocultural export cultivation of citrus, banana, papaya, water melon, tomatoes, and other crops, and on monocultural root cropping, has led to widespread deforestation and agrodeforestation. Concomitantly, polycultural root and tree cropping has declined, existing tree groves have been neglected, and large areas of previously important fallow forests and associated tree species have been cleared. Agrodeforestation and the cultural abandonment of traditionally important trees on Rarotonga and Aitutaki have perhaps been worse than in most areas of the Pacific, although similar trends are evident elsewhere - as in Tonga, where 90 farmers, in a survey of 100 farmers, reported declining numbers of trees on their own fields (Kunzel 1989, 27). If not reversed, such trends could lead to the abandonment of agroforestry traditions that have sustained the highly sophisticated hierarchical societies of Polynesia for many centuries.
Tongatapu, the largest and most populous island of the Tongan group, is an upraised limestone island, approximately 257 sq km in area, lying just within the tropics. Its mild and moist climate, with a mean annual temperature of 23°C, a seasonal range of only 4°C, and a mean annual rainfall of 189 cm, provides a favourable agricultural environment. The soils are fertile, deep friable clays of prehistoric volcanic origin that overlay the upraised coral-limestone base of the island. Little soil erosion occurs on the mostly flat surface, the highest elevation being only 83 metres above sealevel. Major constraints to agriculture include the absence of surface streams or surface water, undependability of rainfall, and frequent tropical cyclones and galeforce winds (Thaman 1976).
Owing to population pressure (over 251 per sq km in 1986) and over 3,000 years of human occupance (Groube 1971), very little primary vegetation remains. Vegetation communities currently that exist include: coastal littoral forest, coastal savanna, swamp forest, marshland, mangrove swamps, and isolated stands of tropical lowland forest, plus the highly modified vegetation communities and fallow and ruderal vegetation found in active agricultural areas and villages and towns.
Agricultural land use
A bush-fallow agroforestry system is practiced on some 5,652 bush allotments ('apt 'uta) averaging about 3.2 ha (8.25 acres by law) in area, to which individual farmers or farm families have individual tenure rights. The characteristic vegetation on Tongatapu bush allotments can be best described as a dynamic mosaic of individualized allotments, each containing a diversity of subsistence and cash ground crops and secondary vegetation in various stages of regrowth, spread throughout a matrix of coconut palms and a wide variety of useful tree species. Also found on many allotments, and considered integral and useful components, are small protected areas of old fallow forest, coastal strand forest, or mangrove forest. Most families also have an additional town allotment ('apt kolo), ranging from 0.1 to 0.16 ha (0.250.4 acre), located in town reserves, where they maintain their permanent residences, a home garden, and associated structures. Some families, however, have permanent residences on their larger bush allotments, with many families maintaining temporary thatched shelters or small houses there for use when needed (Thaman 1975, 1976).
The cropping cycle begins with the clearing of secondary vegetation, including many pioneer tree species, while protecting (although sometimes pruning or pollarding) useful species, the most common being coconut, breadfruit, mango, citrus, Tahitian chestnut (Inocarpus fagifer), oceanic Iychee (Pometia pinnatae), candlenut (Aleurites moluccana), and koka (Bischofia javanica). The dried plant remains are then usually burned, and the first crop, often yams (Dioscorea alata), is planted, and usually intercropped with plantains (Musa AAB Group), giant taro (Alocasia macrorrhiza), or other crops. After the yams are harvested, true taro (Colocasia esculenta) and tannia (Xanthosoma sagittifolium) or cassava are generally the next crops in the succession. Other crops, including sweet potatoes, bananas, peanuts, paper mulberry (Broussonetia papyrifera), or Lava (Piper methysticum), are also integrated into the cropping sequence and may be planted at any time during the sequence. If taro has been planted, cassava often follows and is sometimes planted up to four or five times consecutively on a given plot. Then, after the cassava is harvested, the land will be allowed to revert to fallow, although some cassava is commonly left as a component in the tumble-down fallow vegetation (Thaman 1975, 1976).
In a sample survey of 101 bush allotments comprising 326 ha, conducted in 1971-1972, approximately 111 ha, or 34 per cent of the area, was under cultivation, with the balance under various stages of fallow regrowth (Thaman 1976). There were 87 allotments with some cultivation and 14 that were not cropped at all. With respect to cultivated land, it was often difficult to differentiate between subsistence and commercial cropping, because crops such as coconuts, bananas, water melons, pineapples, garden vegetables, and peanuts, which are commonly grown for export or local sale, are also used for home consumption. Conversely, many important subsistence crops such as cassava, yams, sweet potato, tannia, and plantains are also produced commercially. On this basis, 97 of the 111 ha under cultivation, or 86.5 per cent, constituted subsistence cropping; 12 ha, or 10.7 per cent, commercial cropping; and 3 ha, or 2.7 per cent, a combination of the two. Of the 87 allotments under some form of cultivation, all had subsistence crops, whereas only 31 had "commercial" crops (Thaman 1975, 1976).
Of the eight species of staple subsistence ground crops, cassava covered 37 per cent of the area, tannia (Xanthosoma taro) 24 per cent, yams 21 per cent, sweet potatoes and taro 3 per cent each, a combination of tannia and Colocasia taro and plantains 2 per cent each, and sweet yam (Dioscorea esculenta) and giant taro (Alocasia macrorrhiza) 1 per cent each. These figures represent areas for these crops as dominants on a given plot and, in the cases of plantains and giant taro (which are commonly intercropped with yams and infrequently planted alone), their relative importance was greater than these figures indicate. Similarly, the relative importance of sweet potato is probably understated because of the time-period selected for the inventory.
A range of supplementary food crops also plays an important role in the Tongan diet. Because most supplementary food plants are either intercropped with staple crops or protected in the fallow vegetation, their frequency of occurrence was surveyed rather than the area they occupied. Of these plants, the papaya was the most widespread, occurring in either a cultivated or semiwild state on 88 per cent of the sample allotments. In only three cases was it planted in rows resembling a plantation. Supplementary food plants present on over 50 per cent of the sample allotments included Cordyline fruticosa, chill) peppers (Capsicum frutescens), and bananas (Musa AAA Group) (planted as isolated or small groups of plants). Plantains (Musa AAB Group), hibiscus spinach (Hibiscus manihot), pineapple, sugar cane, and pata variety bananas (Musa ABB Group) were found present on at least 25 per cent; wild or cherry tomatoes (Lycopersicon esculentum var. cerasiforme), pumpkin, kava (Piper methysticum), and corn on at least 10 per cent; with the remaining supplementary food plants found on the bush allotments (which bring the total to 18) including green or bunching onions (Allium spp.), coffee, lemon grass (Cymbopogon citratus), Amorphophallus campanulatus, and granadilla (Passiflora quadrangularis).
Throughout the matrix of staple and supplementary food crops and secondary vegetation are a number of important non-food plants. The most common non-food plants, which are both cultivated and protected in a natural state, are a number of species or cultivars of pandanus (Pandanus spp). These provide fibre for baskets, mats, and other handicraft items and were present on 76 per cent of all allotments. On four of these allotments, solid plantings averaging about 0.1 ha were found. Second in frequency to pandanus, but occupying considerably more area, was paper mulberry (Broussonetia papyrifera) (used for making tape cloth), which was planted on 38 per cent of the sample allotments and comprised about 3 per cent of the subsistence area. Other plants useful for construction, wrapping food, decorative purposes, handicrafts, scenting oil, adhesives, and medicinal purposes included bamboo (Schizostachyum glaucifolium and Bambusa vulgaris), Heliconia indica, cycad (Cycas circinalis), Job's tears (Coix lachryma-jobi), members of the ginger family (Zingiber zerumbet and Amomum cevanga), sword grass (Miscanthus foridulus), Polynesian arrowroot (Tacca leontopetaloides), maile (Alyxia stellata), cotton (Gossypium barbadense), tobacco, tumeric (Curcuma longa), and 'uhf (Euodia hortensis).
Of the non-tree crops classified as commercial - although many of them are also of subsistence value - bananas (Musa AAA Group) covered 42 per cent of the area, water melons 17 per cent, plantains (Musa AAB Group) 13 per cent, pineapples 11 per cent, tomatoes and sweet capsicum, or bell pepper (Capsicum annuum var. grossum), both 6 per cent, and peanuts 4 per cent. The balance of the area was made up by rock melons (Cucumis melo var.), corn, and vanilla (Vanilla fragrans), all in contiguous plots. Subsequent to the survey, there has been an expansion of monocropping of butter squash (Cucurbita sp.) for export to Japan. All of these crops, with the possible exception of vanilla, also have subsistence value that, in some cases, may be greater than their commercial value. Bananas in particular, which are cooked in a green state, were, in 1971, one of the major staple foods, together with cassava, American taro, and yams (Thaman 1976).
Trees and agroforestry practices
Although the major staple and commercial crops dominate the cultivated area of bush allotments, the most prominent plants are trees. The coconut palm, which was present on over 98 of the 101 surveyed bush allotments, was by far the most common and most important cash crop on Tongatapu, as well as being the most frequently consumed subsistence crop. Over half of the allotments had over 200 mature palms, whereas some had 500 or more, the median coverage being about 250 palms. Although 56 allotments also had immature replanted coconuts, in only a few instances were they wellmaintained (Thaman 1976, 257-258).
In addition to coconut palms, there were at least 25 other fruit trees among the plant associations. Trees, primarily important because of their edible fruit, present on over half of all sample allotments, included mango (Mangifera indica), citrus (including Citrus sinensis, C. reticulate, C. hystrix, C. aurantium, and C. aurantiifolia), oceanic Iychee (Pometia pinnata), breadfruit (Artocarpus altilis), Tahitian chestnut (Inocarpus fagifer), and guava (Psidium gunjava). Other common species included avocado (Persea americana), beach almond (Terminalia catappa), soursop (Annona muricata), Polynesian vi-apple (Spondias dulcis), and Malay apple (Syzygium malaccense). Other species such as sugar apple, or sweetsop (Annona squamosa), rose-apple (Syzygium jumbos), cocoa (Theobroma cacao), cashew nut (Anacardium occidentals), the common fig (Ficus carica), apple (Malus pumila), and peach (Prunus persica) were also found as isolated individuals on allotments on some occasions.
Of even greater importance in terms of numbers and frequency of occurrence are at least 67 other non-food tree species, all useful in some way to Tongan society. They are generally found in a protected state, although sometimes deliberately planted. Apart from the value of their timber, their fruit, seeds, leaves, bark, wood, and roots are used in the preparation of medicines, dyes, handicrafts, cordage, scent for coconut oil, soap substitutes, handicrafts (including wood carving), canoe construction, and other material goods. The most common trees in this category include Bischofia javanica, Aleurites moluccana, Hibiscus tiliaceus, Morinda citrifolia, Macaranga harveyana, Rhus taitensis, Grewia crenata, Erythrina variegate, Glochidion spp., Pandanus tectorius, Ceiba pentandra, Santalum yasi; Cananga odorata, Pittosporum arborescens, Pisonia grandis, Elatto stachysfalcata, Garciniasessilis, Adenantherapavonina, Mertyamacrophylla, Ficus scabra, Micromelum minutum, and bamboos (Schizostachyam glaucifolium and Bambusa vulgaris), all of which were found present on over 10 per cent of all allotments.
Other species of widespread agroforestry importance throughout the Pacific, found on over S per cent of the sample allotments and which, in some cases, constitute endangered species, include Cerbera manghas, Diospyros laterifolia, Jatropha curcas, Ervatamia orientalis, Grevillea robusta, Syzygium corynocarpum, Xylosma orbiculatum, Plumeria rubra, Syzygium clusiaefolium, Neisosperma oppositifolium, Trema orientalis, and Dysoxylum forsteri. Other species of particular cultural significance or utility, found on less than 5 per cent of allotments, some of which must be considered endangered species, include Garuga floribunda, Parinari glaberrima, Fagraea berteriana, Diospyros ferra, Ficus obliqua, Calophyllum inophyllum, Myristica hypargyraea, Pimenta racemosa, Burkella richii, Casuarina equisetifolia, Tarenna sambucina, Homolanthus nutans, Aglaia saltatorum, Syzygium neurocalyx, and Premna serratifolia.
Most of the tree species found on bush allotments are native to Tonga or are aboriginal introductions, although recent introductions such as Leucaena leucocephala, kapok (Ceiba pentandra), Jatropha curcas, and frangipani (Plumeria rubra) were also common. There are also a number of species introduced by the government as part of reforestation schemes; these include the silky oak (Grevillea robusta), blue gum (Eucalyptus spp.), and cigar box cedar (Cedrela odorata), which have been planted, either as small woodlots, border plantings, or scattered individual trees, on some allotments.
Fallow and natural vegetation
Another dominant vegetational feature on bush allotments was the fallow or secondary vegetation, which has a very important role in the cropping succession. Approximately two-thirds of the combined area of all sample bush allotments were under some stage of bushfallow or natural vegetation, with some allotments (14 per cent of the sample) completely under various stages of fallow vegetation. In no case was an individual allotment under 100 per cent cultivation. There were, however, very few areas under fallow for sufficient time for forest to regenerate. Only 9 per cent of the uncultivated area had been under fallow over 10 years, the majority of which comprised uncultivable stands of coastal strand or swamp forest. Another 21 per cent had been under fallow for approximately 5-10 years, with the remaining 70 per cent having been under fallow for less than 5 years and being characterized by bushes, grasses, and ephemeral pioneer species, most of postEuropean-contact introduction, and few trees. Extensive areas of fallow vegetation, especially in the eastern, or Hakake, district, were under almost monospecific stands of Leucaena leucocephala, which spread so fast and is so difficult to clear that people considered it a weed (Kunzel 1989, 41), while recognizing the tree's value as an enhancer of soil fertility and a major source of saleable firewood.
Similarly, many of the other fallow species (which number more than 60) are useful as sources of food, medicines, firewood, fodder, fish poisons, and other valuable products; but some, such as Cyperus rotundas, Commelina spp., and Psidium gunjava, spread so rapidly as noxious weeds that they have become the focus of control programmes.
As suggested above, in addition to the cultivated and protected plant species and fallow vegetation, a number of allotments also had uncultivable areas under "natural" vegetation. These allotments were usually found along the coast and included areas of littoral or coastal strand forest (on the higher windward southern portions of Tongatapu) and swamp or mangrove forest (on the low-lying leeward northern coast). Although of limited agricultural potential, such areas constitute sources of many useful products, and embody gene pools of species rapidly disappearing from a majority of Tongatapu bush allotments, as well as serving as buffer zones protecting crops and soils from sea spray and salt-water incursion.
Rotuma is an isolated volcanic island to the north-north-west of the Fiji group, with fertile, well-drained basaltic soils, an area of some 45 sq km, and a population of around 3,000. The majority of its indigenous Polynesian people (approximately 5,000) have emigrated to the main Fiji group, thus relieving pressure on Rotuman land.
Ecologically, Rotuma illustrates the human ability to design with Nature to create productive and sustainable agroforestry. The dominant staples - yams, Colocasia, Xanthosoma, and Alocasia taros, cassava, and a wide range of banana cultivars - are grown in a shifting system, with old gardens having been so commonly planted with coconuts, breadfruit, oranges, and other trees that most of the island
Table 6 Sampling frequency of mature tree species from 40 sites along a 2-km transect on Rotuma island, F'iji (bananas or plantains [Musa spp.] and papaya [Carica papaya], which were very abundant, have been excluded) appears to be part of a giant plantation - but decidedly a polycultural plantation, with many other useful trees interspersed with the coconuts, and small groves of secondary forest containing both indigenous and exotic species of great cultural utility. In order to convey an image of the orchard-like character of Rotuma's agricultural landscape, data collected on a 2-km transect are summarized in table 6. The transect was run from the coast inland along a line close to the trans island road. The survey technique used enabled 120 trees to be identified at 40 sampling points. Aside from the very common Musa cultivars and papaya, which were excluded from the sample, only 19 species of trees were identified. This uniformity, when contrasted with the greater diversity recorded in more comprehensive botanical studies of the entire island and of secondary forest groves, demonstrates how what would have been a considerably greater natural diversity has been transformed into a quasi-orchard, a sort of tamed forest of mostly useful trees. Only about a quarter of the trees recorded had grown spontaneously; the rest had been planted.
|Botanical name (Rofuman; common names)||Frequency||Comments|
|Cocos nucifera (niu; coconut)||58||The coconut trees provide Rotuma's major export (copra) as well as a variety of materials and several nutritious additions to the Rotuman diet; planted and volunteer.|
|Artocarpus altilis ('ulu, ulu; breadfruit)||43||Major seasonal staple prepared and eaten in a variety of ways; made
into traditional pudding or dessert, fekei; trunk favoured for canoes;
|Morinda citrifolia (ura; beach mulberry)||38||Small fruits pounded and mixed with water for children's cough syrup; leaves soaked in oil to put on boils; spontaneous volunteer; fruit eaten by older persons.|
|Citrus sinesis (mori; orange)||15||Plantings of the famous Rotuman orange - highly esteemed in Suva - have increased in recent years as demand for their export has grown; also used in renowned Rotuman "orange wine"; planted occasionally, usually spontaneous.|
|Inocarpus fagifer (ifi, Tahitian chestnut)||13||Frequently used as a boundary marker; edible seed; planted and spontaneous.|
|Macaranga spp. (sa'a)||10||Sometimes planted by seedling near houses; light wood used for canoes and house flooring; good firewood; medicinal use; spontaneous in fallow lands.|
|Hibiscus tiliaceus(hau; beach hibiscus)||8||The pan-Pacific beach hibiscus; traditionally an important fibre plant; important medicinally; spontaneous, occasionally planted.|
|Flacourfia rukum (firmoto; governor's plum)||5||A very abundant spontaneous naturalized tree in the forest, along roads, and in coconut plantations; wood used forhouse and fence posts and fuel; fruit eaten.|
|Mangifera indica(mago; mango)||5||Common tree; nutritious fruit; good firewood.|
|Pometia pinnata (fao, fava; oceanic Iychee)||5||Fruit eaten; excellent firewood and good timber; medicinal value.|
|Ceiba pentandra (sipi; kapok)||5||Silk cotton used for stuffing pillows and mattresses; occasionally used as a living fence; planted.|
|Spondias dulcis (vi; Polynesian plum)||5||Planted around houses for its delicious fruit; said to be spontaneous in the interior and in plantations.|
|Citrus hystrix (rough lemon, kaffir lime)||5||Fruit important for making drinks, spicing food, and marinading sea food; leaves used medicinally and in herbal teas; planted and spontaneous.|
|Pandanus sp. (sa'aga)||3||Planted for leaves, which are used to make fine white mats.|
|Psidium gunjava (guava)||3||Fruit a nutritious seasonal snack food; leaves medicinal; excellent firewood; spontaneous.|
|Theabroma cacoa (cocoa)||3||Cocoa, tried as an export crop, is not presently harvested; pulp surrounding seed eaten as a snack food; planted.|
|Pipturus argenteus (armea)||3||Wood, which is strong but light, is used for canoe paddles.|
|Swietenia macrophylla (ai hapa; mahogany)||3||A recent introduction; timber tree.|
|Erythrina orientalis (ratu'a; coral tree)||3||Planted as a boundary marker and living fence; used medicinally.|
|Metroxylon vitiense (ota; sago)||3||Planted for the thatch; starch from trunk used occasionally in puddings.|
Other important tree species found in reconnaissance surveys of active garden areas, various stages of fallow vegetation, and protected secondary forest stands included Dracontomelon vitiense, Terminalia catappa, Elaeocarpus grandis, Syzygium spp., Sterculia fanaiho, Gardenia fijiensis, Diospyros spp., Dysoxylum spp., Intsia bijuga, and Neonauclea forsteri.
Closely connected with Rotuman agroforestry is the pig-rearing system, wherein the animals are kept in large communal stone-walled enclosures located separately from garden lands in protected secondary forest stands, often between villages and inland gardens. Trees provide much of the pig food, notably coconuts and the abundant papaya. Also of great abundance are a wide range of banana and plantain (Musa) cultivars, including the mountain banana (Musa troglodytarum), which are eaten both green as a starch, and also ripe as a fruit and in a variety of puddings. It has been suggested that banana cultivars may, along with Colocasia taro and cassava, be among the most universally important staple food crops in the Pacific (Thaman 1987). The diversity of banana cultivars (about eight) and their many uses on Rotuma bear this out.
Although it is difficult for an outsider - particularly if a whistle-stop central planner, let alone a trained botanical researcher - to inventory or fully to comprehend the Rotuman agroforestry system, it clearly contains much diversity in species and cultivars and contributes much that is of cultural, economic, and ecological utility. Although much of Rotuma's landscape is forested, it is a much modified landscape, laced with planted or preserved trees and designed to meet human needs. After their fieldwork on the island, Thaman and Clarke (1987) commented that walking through Rotuman forests is- appropriate changes being made - not unlike strolling in the gardens of Versailles, except that the Rotuman land use is so much more productive of foods and useful materials.
Rarotonga and Aitutaki, two small islands in the southern Cook Islands, have agroforestry systems that have been subjected to relatively high population densities as well as to strong pressures from urban growth and the commercialization of agricultural production.
Rarotonga, with a total land area of 67 sq km, is a high basaltic island with a rugged forested interior rising to 652 metres, areas of highly degraded bush and fern-clad hills, deep well-watered valleys, and a fertile low-lying, somewhat swampy coastal plain fringed by a narrow, slightly-raised sandy coastal strip. With Mangaia, the second-highest island in the Cook Islands, reaching only 168 metres, the native upland vegetation of Rarotonga is not found elsewhere in the Cook Islands (Merlin 1985,84).
Agricultural activities in Rarotonga have traditionally focused on taro cultivation in the rich soils of the swampy lowlands and the alluvial and colluvial soils of stream valleys surrounding the mountainous interior, with diversified agroforestry and other root cropping being practiced throughout these areas, as well as on extensive areas of colluvial soils on the lower slopes and interfluves of the interior and in home gardens in villages located on the lower slopes of the interior and on the well-drained coastal strip. The current population of Rarotonga is estimated to be over 10,000, which constitutes over half of the 15-island country's population.
Aitutaki, a smaller island lying some 225 km north of Rarotonga, has a total area of 19.9 sq km and an estimated 1981 population of 2,335 (Douglas and Douglas 1989). The land area consists of a somewhat lowlying volcanic island, rising to a maximum elevation of 137 metres at Maunga Pu (Sykes 1976), with limited areas of alluvial valleys and coastal plain surrounding upland agricultural areas and highly degraded scrub lands and fern lands at higher elevations. There are also a number of low-lying coralline and volcanic reef islets, or motu, surrounding an extensive lagoon, "generally considered to be one of the most beautiful in the Pacific" (Douglas and Douglas 1989, 53).
Agroforestry activities on both islands have been seriously affected by emigration, heavy emphasis on export cash cropping, and increasing monetization, as well as other urban-biased developments, particularly tourism, and increasing educational, economic, social, and nutritional dependence on New Zealand.
Because of the unusual political status of the Cook Islands, first as a New Zealand colony since the turn of the century and then, since 1964, as a self-governing state in free association with New Zealand (with Cook Islanders remaining New Zealand citizens with free access to New Zealand), there has been steady emigration of Cook Islanders to New Zealand since World War II, with well over half of all Cook Islanders now residing there (Douglas and Douglas 1989). Remittances from overseas Cook Islanders in New Zealand, as well as from those in wage employment on Rarotonga, to outer islands such as Aitutaki constitute the major source of income for many families.
The main agroforestry zones on Rarotonga and Aitutaki are:
Aitutaki, being a smaller, older, lower island than Rarotonga, has very limited areas of poorly drained lowland and virtually no indigenous upland forest.
Home and village gardens
Because of the emphasis on commercial cropping and the highly derived nature of the vegetation at lower elevations, especially on Aitutaki, it is in home and village gardens that one finds agroforestry at its most diverse. On both Rarotonga and Aitutaki, home agroforestry is characterized by a wide range of fruit-trees, ornamental trees and shrubs with fragrant flowers or leaves, and a number of other useful trees, which serve as a matrix for lawns, structures, and scattered flower gardens.
Most common among the fruit or edible-seed trees are coconut palms, breadfruit, mango, citrus trees, papaya, avocado, guava (Psidium guajava and P. cattleianum), Tahitian chestnut (Inocarpus fagifer), the red-bead tree (Adenanthera pavonina), sweetsop and soursop (Annona squamosa and A. muricata), Polynesian vi-apple (Spondias dulcis), Malay apple (Syzygium malaccense) and beach almond (Terminalia catappa). Among the citrus trees, species such as limes and lemons, which are commonly required for marinading raw fish (ika mata) and which are not normally planted in the larger commercial citrus plantations, are usually found near homes. Mandarin orange, grapefruit, and the orange are also common in home gardens.
Other fruit-trees occasionally found in home gardens include jakfruit (Artocarpus heterophyllus), carambola (Averrhoa carambola), the star apple (Chrysophyllum cainito), koko (Inga edulis), tamarind (Tamarindus indica), the Pacific fan palm (Prichardia pacifica), and a range of fruits, all referred to locally as vinevine, including Surinam cherry (Eugenia uniflora), white mulberry (Mows alba), governor's plum (Flacourtia ramontchi), acerola (Malpigia glabra), and the sea grape (Coccoloba uvifera).
Common non-fruit trees found in home gardens include Norfolk Island pine (Araucaria heterophylla), banhinia (Bauhinia spp.), kapok (Ceiba pentandra), flame tree, or poincianna (Delonix regia), coral, or dadap, tree (Erythrina variegata), beach hibiscus (Hibiscus tiliaceus), pandanus (Pandanus spp.), bay rum tree (Pimenta racemosa), frangipani, or plumeria (Plumeria rubra and P. obtusa), African tulip tree (Spathodea campanulata), and yellow bells (Tecoma stans).
Among tree-like shrubby species, the Tahitian gardenia (Gardenia taitensis) is particularly common and very important, along with the frangipani, in the production of the ubiquitous flower garlands, or lets, that are still of considerable cultural and economic importance, both for everyday use and for the expanding tourist industry. Other common shrubby species, most of which are referred to as kapaie (literally hedge), commonly planted as living hedges or fences or as ornamentals, include a number of panax species (Polyscias guilfoylei, P. scutellaria, P. balfouriana, and P. tricochleata), the copper leaf, or beefsteak, plant (Acalypha amentacea), croton (Codiaeum variegatum), cordyline (Cordyline fruticosa), the caricature plant (Graptophyllum pictum), and the common hibiscus (Hibiscus rosasinensis).
Coastal and strand agroforestry
Because the sandy low-lying coastal zone and smaller offshore islands are commonly owned and used by the same families who actively cultivate inland gardens, these areas can be seen as integral parts or extensions of the agroforestry system. Moreover, such areas border or extend into agricultural areas as well as being integral components of coastal home gardens.
The dominant trees or tree-like shrubs in the outermost zones, which are most exposed to salt spray, include Messerschmidia argentea, Leucaena insularum, Sophora tomentosa, and the often dominant saltbush, or halfflower, Scaevola sericea. Two very hardy plants known locally as ngangie, Pemphis acidula and Suriana maritima, which seem to be absent on Rarotonga- possibly because of human clearance, although they may never have been present (Sykes, 1976) are common on the reef islets, or motu, of Aitutaki.
In more sheltered areas on Rarotonga, beach hibiscus (Hibiscus tiliaceus), Indian mulberry (Morinda citrifolia), and Pipturus argenteus are common, with Hibiscus tiliaceus forming dense stands. Emergent coconut palms commonly dominate this somewhat shrubby vegetation formation, which merges on its inner margin with semi-open, semi-natural or planted coconut groves (Sykes 1976). Similarly, on Aitutaki, Hibiscus tiliaceus, often along with Pandanus tectorius, dominates large areas along the coast, especially between Tautu and Vaipae, where lateritic soils overlying the volcanic bedrock reach the sea (Sykes 1976).
Where the indigenous vegetation has not been cleared for coconut monoculture, or in coastal areas where indigenous strand species have not been felled or replaced by home gardens, dominant large trees include Barringtonia asiatica, Calophyllum inophyllum, Hernandia nymphaeifolia, and Pisonia grand is, with Casuarina equisetifolia being abundant locally in coastal areas on both Rarotonga and Aitutaki. Guettarda speciosa and Pandanus tectorius are also quite common locally in coastal areas of Aitutaki, especially near the Ootu airstrip, and on some of the reef islets. Thespesia populnea is reportedly found on some reef islets of Aitutaki (Sykes 1976), and, along with Cordia subcordata (both endangered coastal strand species highly valued for wood carving in the Cook Islands), it is currently being planted along roads on the coastal strip of Aitutaki as part of current nationwide conservation activities.
On Aitutaki, coconuts are similarly ubiquitous emergents along sheltered lagoons, as well as the dominant tree on the more productive coastal fringe areas, with large numbers of regularly-spaced palms having been replanted after World War II deforestation to make way for an airstrip. Most palms, however, except some along the north coast of Aitutaki, which have been planted as part of a coconut rehabilitation scheme, are irregularly spaced, often in dense stands (Johnston 1967).
Agroforestry in poorly drained lowlands
On Rarotonga there are extensive poorly-drained agricultural lowlands, or pa'i, which constitute the most important taro-growing areas on the island. They are dominated almost entirely by excavated and mulched swamp taro (Colocasia esculenta) cultivation and fallowed taro beds in various stages of abandonment. Scattered throughout these areas are a wide range of planted or protected trees, usually along the bunds and pathways between plots or on scattered areas of high ground. Although only limited studies of these areas were conducted, the main trees in these pa'i areas include coconut palms, Tahitian chestnut, mango, Polynesian vi-apple, guava, Hibiscus tiliaceus, the jambolan (Syzygium cumin)), and banana and plantain cultivars. Although not the dominant vegetation, these scattered trees add important diversity and welcome shade and snack foods for gardeners in these highly productive agricultural areas, which have provided Cook Islanders with their traditionally important staple, taro, for over a thousand years.
On Aitutaki, areas under swamp taro cultivation were very limited in extent and found only in small patches inland and along the east coast. Where such swamp taro gardens exist, similar tree species to those on Rarotonga were often associated with them, particularly Hibiscus tiliaceus, which bordered some gardens.
Agroforestry in the uplands and inland gardens
Well-drained upland and interior garden areas extend inland from the coastal strip and the poorly drained taro swamps up to heights of 50-200 metres on Rarotonga and up to some 100 metres on Aitutaki. In these areas, traditional diversified agroforestry once predominated, but mostly has been gradually replaced by monocultural root cropping and institutional plantation culture of citrus, pawpaw, and tomatoes on Rarotonga and citrus, bananas, and tomatoes on Aitutaki. Johnston's (1967) study of agriculture on Aitutaki and Wilder's (1931) Flora of Rarotonga provide some indication of what the system was like prior to World War 11.
Whereas on Rarotonga there are still scattered groves of trees in some areas, particularly in well-watered valleys and beyond the limits of current cultivation, these are now virtually absent on Aitutaki, where there was an absence of primary forest by the early 1960s as a result of the "rotational bush fallow" agricultural system in which areas of active garden production for a given family were rotated "through a fixed area of fallow grass or woody plants where woodland is not allowed to regenerate" (Johnston 1967,28).
In both areas, permanent cultivation or protection of useful trees such as coconuts, citrus, breadfruit, mango, Tahitian chestnut, avocado, papaya, oceanic Iychee (Pometia pinnata), matakoviriviri (Adenanthera pavonina), kapok, and candlenut (Aleurites moluccana), and a wide range of banana and plantain cultivars - was also an integral part of the system.
Even the export citrus industry, which flourished from the late nineteenth century until the 1930s, was based on the "haphazard" (in Johnston's view) production of dispersed "wild" orange trees, which had been incorporated into the subsistence economy and were found scattered among other tree crops (Johnston 1967, 50-51). As late as the 1950s, these "wild oranges," which included fruit from trees scattered in the forest beyond the limits of cultivation, still constituted the overwhelming proportion of citrus production and exports (Johnston 1951, 130).
Evidence indicates that a fallow period of 10-20 years, followed by a cropping period of 2-4 years, was the traditional fallow-crop cycle. By 1960, however, fallow periods had dropped to only 5 years, and to as low as 1-2 years in more accessible areas closer to villages, with the cropping period remaining the same (Johnston 1967, 34-35), a process that explains the absence of primary forest and a scarcity of secondary forest in the gardening areas.
Although the traditional criterion for selecting garden sites was sufficient regrowth of mature secondary forest, land that had lain fallow for 10-20 years was extremely limited (Johnston 1967, 29). What forest did exist usually consisted, as it does today, of limited areas of relatively mature, almost homogeneous, stands of au (Hibiscus tiliaceus) and, in some cases, guava. Priority in use of such areas was given to bananas, which bear for 5-10 years on one plot, although existing banana areas and individual family needs were taken into account. Yams were almost always planted on newly cleared land, where uncleared trees and stumps provided trellising or support for the vines. Other non-tree and root crops were usually planted on land cleared from younger secondary forest, areas of bush-fallow, or in succession after the harvest of the previous crop, although tomatoes were also commonly planted on recently cleared fallow land, but generally in less mature areas that were relatively easy to clear (Johnston 1967, 15, 21-30).
Plot histories indicated that bananas were always planted for a minimum of 5 years, with some varieties for at least 10 successive years. Cassava was generally planted for 2 years in succession, although sometimes for 4 years, whereas yams, sweet potatoes, tan nia (Xanthosoma taro), and tomatoes were generally planted only once in succession on a given plot, although tannia was occasionally planted for 2 years (Johnston 1967, 33).
Of the major food crops, coconuts excepted, cassava was most common, covering 39 per cent of the area under crops. Reportedly introduced by the missionaries in the last century to supplement mission funds, cassava spread rapidly, possibly because of the prestige growers received by contributing to the church and the ability of cassava to grow in the conditions of relative water scarcity and declining soil fertility on Aitutaki, conditions that restrict the growth of wetland tarot Bananas or plantains cover 29 per cent, and tannia (Xanthosoma sagittifolium) 12 per cent. Other crops such as sweet potato, taro, yams, and minor crops such as melons, pumpkins, and onions, covered 7.8 per cent, and the two major commercial crops at the time, oranges and tomatoes, constituted 7.6 per cent and 4.6 per cent of the area respectively, making up the balance of the area (Johnston 1967, 14-21).
Although second in importance in terms of area, banana or plantain plots were the most common, with over two-thirds of all gardens containing them as one of several crops or as the sole crop, with some plots bearing up to 15 years. Moreover, such plots were the most localized and often at a greater distance from the village than root crops (Johnston 1967, 13-14).
Cassava and sweet potato were almost always planted as monocultures, and bananas and tannia usually as monocultures, although 18 per cent of tannia plots had been intercropped with bananas for 23 years. Intercropping was characteristic only of yam plots, which were often interplanted with bananas or tannia and occasionally with cassava.
Tree crops were scattered throughout garden areas, as were mixed groves of valuable trees. Coconut palms, the dominant crop on the coastal fringe, were found as isolated individuals or irregular clusters. Tahitian chestnut, mango, breadfruit, papayas, rough lemon, Malay apple, Polynesian vi-apple, and avocados, along with the widespread wild "native" orange and a range of other useful trees, including kapok, the banyan (Ficus prolixa), mata'oi (Cananga odorata), and candlenut, were the main trees, although breadfruit was more commonly found around villages, particularly on Aitutaki (Johnston 1967, 16).
On Rarotonga, where extensive areas of low-lying swamp taro beds and systems of irrigated taro terraces existed historically to take pressure off interior and upland garden areas, trees were more numerous than on Aitutaki, with a much greater range of trees being found either planted or naturalized in interior and upland agricultural areas.
Hibiscus tiliaccus was, and still is, the commonest and often dominant tree, with Tahitian chestnut (Inocarpus fagifer) and the candlenut (Aleurites moluccana) being particularly common in valley entrances and on lower slopes on Rarotonga. Formerly cultivated trees that have become extensively naturalized on Rarotonga include Cecropia palmata, Inga edulis, mango, and jambolan (Syzygium cumin)). Commonly found around garden areas, especially on the lower slopes of the mountainous interior, are Bischofia javanica, Homalium acuminatum, and Xylosma gracile, which Sykes (1976) believes to be "almost certainly . . . principal components of the original forest." Homalium acuminatum (moto) - the durable wood of which was formerly important in canoe construction and which was formerly "common from sea-level to 1000ft" - is one of the few native trees still occasionally found around plantations where it "was most likely the 'most common dominant' before human disturbance" (Cheeseman 1903; Sykes 1976, quoted in Merlin 1985, 90).
Other species found in the more disturbed areas of the lower montane slope forest include Elaeocarpus rarotongensis, Weinmannia rarotongensis, Macaranga harveyana, Planchonella grayana, and Terminalia glabrata, with Fitchia speciosa found in the more recently disturbed sites (Merlin 1985, 89). In the case of Bischofia javanica, some authorities such as Whistler (1980a) and Thaman (1988g) believe that B. javanica could have been a deliberately cultivated aboriginal introduction that, because of its widespread cultural importance as a source of dye for tape cloth, its use as a medicinal plant, its value as a sign of soil fertility, and its ability to withstand human abuse, remains as a relict or a possible natural dispersal from ancient garden areas. It was particularly common in most valleys and hillsides at lower elevations in the 1920s (Wilder 1931, 70), is common in low-elevation disturbed forest (Merlin 1985), and is still quite common on lower mountain slopes and surrounding old irrigated taro terraces, such as in the Takuvaine Valley.
The pattern of shifting cultivation amongst scattered fruit-trees and other useful trees and permanent tree groves has, however, been significantly altered because of increasing emphasis on commercial and subsistence monocropping, which began as early as last century and which has accelerated since World War II with the systematir institutional promotion of comercial export cropping coupled with the increasing monetization of the economy. The earliest changes were probably the introduction of cassava by the missionaries to raise funds for the church and tannia (Xanthosoma sagittifolium) - both of which grow well on drier upland soils. Both are commonly grown as monocrops and are rarely intercropped because of their ability to grow under conditions of declining soil fertility. Increased cassava cultivation, in particular - cassava is commonly planted up to four times in succession on the same plot of land - is a major factor in deforestation and agrodeforestation and the movement towards shorter fallow periods. On Aitutaki, cassava, in addition to being a prestige crop because of its association with "Christians contributing to the church," has also been an important supplementary cash crop for export production of starch.
The trend towards agrodeforestation continued in the 1930s, when intensive clearing of wild oranges to obtain land for seasonal planting of tomatoes took place, and when increasing dependence on cash incomes from expanding employment opportunities in areas such as teaching, the medical profession, and government service, coupled with contract work in the phosphate mines on Makatea in French Polynesia and emigration and associated cash remittances, began "drawing people away from the soil" (Johnson 1951, 125).
About the same time, due to falling production from wild orange trees, many of which were dying of old age and uncontrolled disease, a citrus replanting scheme was instituted by New Zealand authorities to shift the production from "haphazard" production of dispersed wild oranges to "scientific plantation agriculture." The scheme was organized so that, once the prospective owner had established secure tenure to a suitable piece of land, the administration took over and "established and matured the young plantation." The "considerable initial and recurrent costs for labour, fertilizers and machine hireage" were charged against the owner's account, to be paid when the trees began to bear, with the owner's sole responsibility being to arrange for the picking of the fruit and, in some cases, weeding and pruning, although few owners in Aitutaki exercised this option (Johnston 1967, 5).
Initially, 100 citrus plots were established on Rarotonga, each of 1.5 acres and containing 90 trees. By 1950 some 150 plots had been established on Rarotonga on the gently sloping garden lands inland from the low-lying taro swamps, or pa'i. The scheme also provided for the establishment of 50 acres on Aitutaki. Johnston (1967, 130) relates that, during this time, many existing tree groves and orange plantings were "devastated" for tomato cultivation, for "new" orange orchards, and commercial cropping of water melon, sweet potato, and tannia for the expanding local urban market. Although orange production was the main focus of the citrus scheme, limited quantities of mandarin orange or tangerine and grapefruit were also processed at the local fruit-processing factory on Rarotonga or exported by sea to New Zealand during the 1960s and 1970s (Department of Agriculture 1979).
During this period, the only government-supported activities related to agroforestry were the planting of dadap (Erythrina variegata) between alternate orange trees, with the foliage being trimmed to provide green manure; and the planting of jambolan (Syzygium cumini), Albizia falcataria, hibiscus (Hibiscus rosa-sinensis), and hedge panax (Polyscias guilfoylei), along with dadap, as wind-breaks or shelterbelts, or with the matured Albizia to provide timber for fruit-cases (Johnson 1951, 129-130).
Unfortunately, production fluctuated, even in the 1960s and 1970s when production was at its peak, with returns to growers being small, and with resultant widespread indebtedness due to charges against the owners, which increased at a faster rate than their repayment (Johnston 1967, 52). Moreover, by 1978, many of the citrus plantings were in a rundown state or beyond their "economic life" of approximately 25 years, thus requiring replanting programmes to rejuvenate the industry (APU 1978). Ward and Proctor (1980, 375) suggest that serious consideration should be given to the possible "winding up" of the citrus industry and the use of land for other purposes, because in only one year during the 1970s did real gross receipts exceed real purchased input costs in the citrus industry, with the net income of producers during other years being "wholly financed by subsidies."
The economic failure of the citrus industry, the low prices received for tomato exports, and a continuing focus on export diversification have led the government and local farmers to look for other commercial agricultural alternatives. Most prominent have been the implementation of banana replanting and extension schemes on both Rarotonga and Aituaki in the 1960s to increase banana exports to New Zealand and the official promotion of plantation culture of papaya for air-freight export to New Zealand. There was also an unsuccessful attempt to establish a commercial pineapple project on Rarotonga in 1966 (Tudor 1972, 143). Also significant have been the increasingly capital-intensive and monocultural production of taro, sweet potato, tannia, and cassava, both for the rapidly expanding local market and for export to New Zealand as well as for subsistence consumption.
As in the case of citriculture, subsidization of production of such activities has been considerable. In the case of the Aitutaki Banana Scheme of 1964, which established a 50-acre nursery and encouraged replanting with free planting material and loans for the purchase of fertilizer, the estimated cost was NZ$106,000, of which NZ$70,000 represented advances to growers. By 1970, 500 acres had been planted under banana replanting schemes on both Aitutaki and Rarotonga (Tudor 1972, 143). Unfortunately, monocultural banana production has always been beset with disease problems, most notably black-leaf-streak fungus and bunchy-top virus, and widespread devastation due to periodic tropical cyclones, not to mention marketing problems related to unreliability of ship transport and competition from Ecuadorean bananas. These problems, plus an increasing focus on the commercial production of papaya and, to a lesser extent, beans and capsicum for air freight to New Zealand, and on rapid tourism development since the opening of the new international airport in 1973, brought about the cessation of banana exports from Rarotonga in the late 1970s, leaving Aitutaki as the sole producing area for export production of bananas in the Cook Islands. As of July 1988, despite a devastating tropical cyclone in December 1987, 150 growers on Aitutaki had 350 acres (141 ha) under banana monoculture, with the individual holdings ranging from 2 to 7 acres. Disease problems and irregularity of transport, however, continue to hinder development of the industry.
Upland forest agroforestry
Although technically not part of the agricultural system, the forest of the hill slopes and mountainous interior of Rarotonga, which in most areas seems to be in nearly its original state (Sykes 1976), contains numerous species of widespread cultural utility and ecological importance and, like the coastal strand forest, must be seen as an extension of the agroforestry system. Such areas take on greater importance as refugia for endangered species as agrodeforestation proceeds in more accessible garden areas. As argued by Merlin (1985, 81), the preservation of the upland forest of Rarotonga, where over 92 per cent of all woody plants are either indigenous or endemic, is particularly important because "the native coastal and lowland vegetation of this high volcanic, tropical island has either been completely removed or heavily disturbed."
The major species in the upland forest include Fitchia speciosa, in more open sites, and Homalium acuminatum, as the dominant in the lowerslope forest areas. Other common species include Hibiscus tiliaceus, which is very common up to 250 metres, Aleurites moluccana, Elaeocarpus rarotongensis, Xylosma gracile, Pittosporum rarotongensis, Bischofia javanica, Macaranga harveyana, and Weinmannia rarotongensis, with Planchonella grayana and Terminalia glabrata being more localized, and the recent introduction, Cecropia palmata, scattered throughout some areas of forest. Common understorey shrubs include Canthium barbatum, Ixora bracteata, Macropiper latifolium, Mertya pauciflora, and, sometimes, Alstonia costata. Numerous lianas of considerable cultural importance, such as Freycinetia wilder) (kiekie), Alyxia elliptica (maire rakau), and Jasminum didymum, are also present (Merlin 1985; Sykes 1976).
On the wetter, higher slopes, Metrosideros collina is dominant, with Fitchia speciosa, Elaeocarpus rarotongensis, Pittosporum rarotongensis, Weinmannia rarotongensis, and, to a lesser degree, Coprosoma laevigata, Xylosma gracile, Geniostoma rarotongensis, Morinda forester), and a small shrub, Vaccinium cereum, being present. On ridge crests, Fagraea berteriana is most dominant, with other species including Fitchia speciosa, Homalium acuminatum, and, to a lesser extent, Canthium barbatum, Alyxia elliptica, Metrosideros collina, Hibiscus tiliaceus, Coprosoma laevigata, and Mertya pauciflora.
Increasing monoculture and agrodeforestation
The impact of export-oriented monocultural agricultural development and increased monocropping of root crops on both Rarotonga and Aitutaki have led to the widespread recent removal of even common useful trees, such as beach hibiscus (Hibiscus tiliaceus), Tahitian chestnut, mango, kapok, Polynesian vi-apple, candlenut, coral tree (Erythrina variegata), matakoviriviri (Adenanthera pavonina), and even coconut palms, as well as recently introduced species such as jambolan (Syzygium cumin)) and Albizia falcataria on both islands. Even the cultivation of a range of banana cultivars, which have long constituted dominant staples, has declined dramatically. Whereas on Aitutaki, there remain few, if any, forest stands or tree groves, except for stands of Hibiscus tiliaceus, on Rarotonga there are large areas of native upland forest, and tree groves can still be found in some areas, with traditionally important species still scattered throughout low-lying swamp and and in upland garden areas.
Some trees that were formerly abundant, such as mata'oi (Cananga odorata), the flowers of which were highly valued for garlands and scenting coconut oil; Malay apple, or ka'ika (Syzygium malaccense), and oceanic lychee, or tava (Pometia pinnate), both with edible fruit; mati (Ficus tinctoria) and ava (Ficus prolixa), the best fibre of which was so important in the manufacture of bark cloth; tou (Cordia subcordata) and miro (Thespesia populnea), two of the most valued woods for wood carving; and other species of widespread medicinal importance throughout Polynesia, such as Glochidion ramiflorum, Alphitonia zizyphoides, and Grewia crenata, to mention only a few, are increasingly rare, and, in some cases, endangered or possibly extinct.
The development processes that have been described in this section have led on Rarotonga and Aitutaki to agrodeforestation and to a cultural abandonment of, and failure to replant, traditionally important trees. The antiarboreal pressures are worse in these islands than almost anywhere else in the Pacific, with the possible exceptions of Nauru and Hawaii. One could go so far as to suggest that a combination of factors has brought about an "agrodeforestation of the mind" in a generation of young Cook Islanders, who neither know the names of their trees nor are able to find one!
Decker's (1971) study of "Plants, Man and Landscape in Marquesan Valleys," although not exclusively focused on agroforestry, provides a thorough description of agroforestry in the inhabited valleys and middle uplands of the Marquesas Islands almost a quarter of a century ago.
The islands of the Marquesas are highly eroded, steep, cliffed remnants of ancient submarine volcanoes. The islands lack coastal plains, except at heads of embayments, but possess large habitable, well-watered amphitheatreheaded or elongate canyon valleys, with boulders in tributary beds upstream and rich colluvium in the back-valleys. Recognizable flood plains occur only in the lower reaches of some valleys. In the absence of coastal plains, backvalley colluvial slopes are the most naturally productive areas and the mainstay of Marquesan agroforestry activities. Because of the steeply sloping nature of the islands, severe erosion threatens unvegetated areas. The two valleys studied in detail by Decker, the relatively wet Puama'u valley on Hivaoa Island and the relatively arid Vaipaete valley on Uahuka, illustrate the range of Marquesan lowland environmental conditions (Decker 1971, 9-31).
Population densities were, until recently, relatively low because of widespread post-European-contact depopulation last century owing to disease and outright slaughter. Population has increased, particularly since World War II, although continued out-migration to Tahiti, New Caledonia, and France has kept populations relatively small. None the less, long human occupation has led to the extinction of many species and the substitution of a largely alien flora for the indigenous flora (Decker 1971, 31), with habitual burning being responsible for Miscanthus tall grasslands and Cleichenia fern lands in upland areas (Decker 1971, 95).
Marquesan agroforestry as a land use can be divided into five zones:
Strand-side and wetlands
Bayshore areas are dominated by vast stands of coconuts with other useful large trees such as breadfruit, mango, and kapok. Relict large trees such as Barringtonia asiatica, Calophyllum inophyllum, and Terminalia catappa, formerly useful to the Marquesans, but rarely planted today, are also found in foreshore areas (Decker 1971, 110). Other ubiquitous strand species, so common in Kiribati and coastal areas elsewhere in the Pacific, are conspicuously rare here, although many can be found in inland forests. Stream bed or riparian and marshy areas are dominated by thickets of Hibiscus tiliaceus, with Tahitian chestnut (Inocarpusfagifer) also common.
Village areas and home gardens
Marquesan villages are located in valleys at a distance from the shore to reduce risk from tsunami damage with dwellings located along principal paths and occupying discretely bounded yards of various sizes. Village or home-garden agroforestry is characterized by a plethora of exotic plants accumulated during some 1,500 years of human arrivals from over the sea, with the accumulation of exotics having increased considerably since European contact (Decker 1971, 124).
Dominant species include the coconut and breadfruit, with mango and kapok (Ceiba pentandra) being very common, along with the ubiquitous and usually spontaneous and protected beach hibiscus (Hibiscus tiliaceus), which forms a part of the backdrop of every village. Common spreading ornamental shade trees include the rain tree, or monkey-pod (Samanea saman) and the flame tree, or poinciana (Delonix regia), with Albizia lebbeck also present in dwelling areas.
Immediately surrounding dwelling areas in uncared-for places, on the islands of Nukuhiva and Uapou, are extensive monospecific stands of Leucaena leucocephala, serving as the main lowland fodder for horses, which are highly useful and abundant draught animals in the Marquesas and which are rotationally fed on Leucaena in the lowlands and grazed on limited areas of upland pasture and shrub land (Decker 1971, 129).
The village home gardens are a very directly useful kind of agroforestry serving as a source of:
Because such plants must be accommodated along with stray animals and children, they are usually hardy, thus favouring trees and tree-like shrubs. Less hardy shrubs and colourful herbs are commonly planted against the house beneath the eaves, with hardier shrubs and trees scattered elsewhere, particularly along borders delineating home-garden boundaries.
The most common staple plants in villages and home gardens are coconuts, breadfruit, and banana cultivars, with important fruit-trees including mango, papaya, lime, avocado, soursop and sweetsop (Annona muricata and A. squamosa), guava, and tamarind. Sugar cane is also common in home gardens.
Tree-like shrubs most commonly planted alone borders include Polyscias guilfoylei, Hibiscus rosa-sinesis, and Gardenia taitensis. All are important ornamentals, with the latter highly favoured for its fragrant flowers, which are used in garlands and for scenting coconut oil. Other trees and shrubs with fragrant flowers or of ornamental importance include the perfume tree or ylangylang (Cananga odorata), bougainvillea (Bougainvillea spectabilis), croton (Codiaeum variegatum), cordyline (Cordyline fruticosa), and the coral hibiscus (Hibiscus schizopetalus). The cultivated pandanus (Pandanus tectorius var. Iaevis), so important in the production of plaited ware, and kapok (Ceiba pentandra) are also common in home gardens (Decker 1971, 141-142).
Where households border streams, hardy useful species, both spontaneous and planted, include Hibiscus tiliaceus, Tahitian chestnut (Inocarpus fagifer), coconuts, kapok, and guava (Psidium spp.). Also found in home gardens are a wide range of non-tree, mostly ornamental, species, but also including staple ground crops, such as taro (Colocasia esculenta), tannia (Xanthosoma sagittifolium, known locally as tarua), and the ubiquitous pineapple (Ananas comosus). Also present is giant taro (Alocasia macrorrhiza), or kape, a staple in western Polynesia and a famine food elsewhere, but serving only as an ornamental and never eaten today in the Marquesas.
Back-valley or up-valley gardens and grove lands
Back-valley or up-valley agroforestry gardens and grove lands are the main sources of Marquesan subsistence and commercial production. With rapid population increase since World War II and recent coconut-planting subsidies, gardens and grove lands, particularly coconut plantings, have expanded into extensive back-valley areas of old fallow forest, much of which remains from agroforestry activities prior to widespread depopulation in the Marquesas during the nineteenth century.
Back-valley agroforestry activities provide:
Marquesan agriculture or horticulture has remained remarkably Polynesian in character, being based on intercropping of long-lived root crops with trees that are mostly vegetatively propagated. The system favours the survival of trees and perennials because of its emphasis on diversity and variety rather than maximum yield, the extensive application of labour in terms of weeding and crop care, and the propensity to intercrop old gardens or clear new land when yields decline. Throughout all Marquesan operations having to do with plants there is an emphasis on the care, protection, and utility of individual plants, rather than on the crop or yield of an entire field or planted stand of trees. Consequently, the word "horticulture" is used advisedly to highlight that emphasis.
For the clearing of new gardens, wooded localities are always preferred because ground preparation is less laborious in the shade where weedy undercover is little developed and soil structure is generally loose. Old fallow areas dominated by Hibiscus tiliaceus are seen as the best sites for gardens, although Xylosma-Sapindus forest and transitional thickets are commonly cleared in drier areas. Edaphic requirements influence site selection, with bananas being planted in wetter alluvial sites, often in sheltered ravines, and cassava higher upslope in lighter soils up to the practical limit of cultivation on slopes up to 30° (Decker 1971, 164).
More permanent difficult-to-clear groves of trees such as Ficus prolixa, Mangifera indica, and Inocarpus fagifer are seldom cleared. In garden clearance, small additions to existing gardens are generally hacked out of the fallow vegetation at almost any time of the year, with Hibiscus tiliaceus being cleared and Ficus prolixa and mangoes generally burned at the base and pruned or pollarded, but left remaining to live in garden sites. After firewood has been saved and temporary shelters of Hibiscus tiliaceus poles and coconut thatch prepared, most areas are burned, although sometimes debris is left to rot in place.
The fallow forest is dominated by many species once of great subsistence utility to Marquesan society. The trees have been spared because they retain some use or because people see them as possessing traditional interest. Marquesan horticulture accepts their presence in gardens as readily as it does large old trees and bulky boulders, thus enhancing the variety and bounty of the new garden. The most common species in this category include the ubiquitous Hibiscus tiliaceus, coconuts, breadfruit, and mangoes, with other useful species spared during garden clearance including papaya, coffee, Tahitian chestnut (Inocarpus fagifer), banyans (Ficus prolixa), candlenut (Aleurites moluccana), Malay apple (Syzygium malaccense), guava (Psidium spp.), beach almond (Terminalia catappa), and Fagraea berteriana, plus a range of coastal strand species.
The persistent dominance of ocean-dispersed coastal strand species in Marquesan secondary forests is remarkable in light of Egler's (1939, 45-46) findings that such plants are poorly adapted for terrestrial migration. The major trees or tree-like plants that fall into this category are Hibiscus tiliaceus, Pandanus spp., Erythrina variegata, Cordia subcordata, Guettarda speciosa, Morinda citrifolia, Premna serratifolia, Sapindus saponaria, Cerbera manghas, and Thespesia populnea, all of which seem to regenerate well and are widely naturalized in inland localities. Other species that occur rather sporadically in old fallow forest or adjacent to suspected former habitation sites included Barringtonia asiatica, Calophyllum inophyllum, Terminalia catappa, and Cocos nucifera, most of which are encountered in fallow forests below 500 metres, with the exception of Hibiscus tiliaceus and Pandanus tectorius, which extend up to the cloud forest. Although illadapted to terrestrial dispersal, all these species possessed utility in the aboriginal economy, which argues strongly for their human carriage inland, a dispersal that would have been reinforced by profound human disturbance of the indigenous vegetation below the cloud zone.
The presence of large inland tracts of old forest fallow can be attributed to internecine warfare before and after European contact. These conflicts led to the retreat of gardens to steeper, secure backvalley slopes. Their persistence, today, in fertile inland valleys reflects the widespread abandonment of pre-1800 subsistence groves after drastic depopulation and a changing settlement pattern, with the abandonment of back-valley dwellings in favour of new coastal villages around foreigners' buildings near bay anchorages and mission dwellings (Decker 1971, 90, 72).
The great plant diversity within garden successions in garden and grove areas results from diverse planting and clearance strategies, all of which minimize toil in the long run. Once a new clearing is planted, soil and plant cover are only minimally disturbed, with minimum tillage with digging sticks or mattocks being used to plant new crops, and weeds being cleared by machete, thus maximizing soil protection against erosion, leaching, oxidation, and the depletion of organic material.
In terms of new garden development, perennial arborescent crops such as coconuts and bananas are sometimes planted in the fallow forest before clearance. When the fallow is finally cleared, if these trees have set little foliage, the debris is burned; otherwise, it is allowed to rot and cleared periodically around the bases of the trees. This practice seems to be followed primarily by individuals planting large areas of coconuts in response to the drive to expand copra production. As a result, it is common to see plantings of immature coconuts only a few years old in areas well along with fallow regrowth. Although perhaps detrimental to optimum growth of coconuts' such a multi-purpose agroforestry strategy is a productive compromise between the aims and resources of both administration and individual Marquesans, providing an investment in future production and being conservative of soil fertility. The fallow vegetation can be recleared slowly, a practice that allows labour input to be spread over time.
After the fallow has been cleared and burned, the staple root crops and various short-lived crops are established, together with a range of banana and plantain cultivars (Musa cultivars) and the less common fe'i banana (Musa troglodytarum), breadfruit, coffee, oranges, avocado (Persea americana), and sugar cane. The garden lasts for three or four years, after which it becomes a grove dominated by trees, aborescent herbs (mainly banana cultivars), and palms, with breadfruit, citrus, and coffee beginning to bear. Bananas and fe'i (huetu) bananas form discrete dense groves. Cassava still persists in the fallow as a source of planting material, with Xanthosoma and giant taro also prevalent, their leaves being used to wrap food. Regularly spaced coconut palms, which have not yet begun to bear, are the only evidence of geometric order. Among the thickening canopy, there remains some spontaneous growth of Commelina diffusa and Oplismenus composites as horse fodder, with a few papayas, chillis, guavas, and Morinda citrifolia, which have been spared, still persisting in some areas. In the few open areas, some grasses, herbs, and shrubs persist (Decker 1971, 188-190).
Of note is the abundance of papaya seedlings in areas recently cleared of fallow, especially Hibiscus tiliaceus fallow. Because of papaya's abundance, it is rarely deliberately planted and is not considered a primary human food, but is fed mostly to animals such as pigs, chickens, and dogs. Other pioneering weeds, such as Commelina diffusa and Oplismenus composites (this latter species occurring in abundance only on the island of Uahoka, where very few alien weeds had become established by the 1960s), are highly valued as horse fodder, as new gardens are among the few places where tethered animals can graze in lowland areas while farmers work in the field. Other weedy species, such as the perennial chill) (Capsicum frutescens), are spared, although shoots of Hibiscus tiliaceus, Morinda citrifolia, and Psidium spp. are usually suppressed by slashing in the early stages of gardens.
Arboreal species, either planted or protected, that persist in backvalley gardens and grove lands include fruit-trees, such as pomelo (Citrus grandis), Malay apple (Syzygium malaccense), hog plum, or Polynesian vi-apple (Spondias dulcis), Inga edulis, mango, Psidium species, and Iychee (Litchi chinensis); other utilitarian species present are pandanus, kapok (Ceiba pentandra), perfume tree (Cananga odorata), Coffea arabica, Tahitian gardenia (Gardenia taitensis), and a range of hibiscus cultivars (Hibiscus rosa-sinensis, H. schizopetalus, and ornamental hybrids). Aleurites moluccana, Canthium barbatum, and Thespesia populnea are found occasionally.
Productive fallow areas and mature groves
As garden groves begin to mature and coconut palms start to bear, some seven to ten years after original clearing, production shifts to copra from food, fibre, leaf, and fodder production, and groves take on a character that may persist for decades. Discrete groves of bananas and fe'i bananas (Musa troglodytarum) and breadfruit still produce in favoured sites, and family groves of Tahitian chestnut (Inocarpus fagifer) remain along with occasional remnant Xanthosoma plants. Sometimes, a new tree is added to an ageing grove. The area around individual coconut palms is generally kept free of high growth by slashing with machetes during the search for fallen mature nuts. Further clearing is brought about by the burning of husks, fallen fronds, and other debris during the extraction of the coconut meat, and the tethering of horses to graze the marginal pasture around each tree (Decker 1971, 195-196).
As coconut groves expand at the expense of old fallow forest and more diversified agroforestry activities, the burden of weeding and brush cutting increases and is made more difficult by the invasion of harder-to-clear shrubby weeds such as Indigafera suffruticosa and Ocimum gratissimum, which make collection of nuts more difficult. The mature grove will eventually consist of the remnants of the original fallow forest, planted trees, and pioneering trees such as several varieties of Hibiscus tiliaceus, Morinda citrifolia, guava (Psidium guajava and P. guineense), mango (Mangifera indica), and kapok (Ceiba pentandra), which exhibits phenomenal reproductive ability in some areas, with some "fallow" forests consisting entirely of tall coconut and kapok trees (Decker 1971, 200).
It is difficult to distinguish advanced stages of matured garden groves from old fallow forest, some areas of which have probably re mained out of cultivation for 100 years or more. Although Hibiscus tiliaceus and Inocarpus fagifer dominate old fallow forests in most back-valley ravines and canyons, harvestable coffee is found naturalized in many, and large banyans (Ficus prolixa), Aleurites moluccana, Terminalia catappa, and Spondias dulcis also remain in these areas. In drier areas of old fallow forest, I. fagifer becomes uncommon, with H. tiliaceus becoming the dominant along with scattered individuals of Canthium barbatum, Glochidion sp., Wikstroemia foetida, Morinda citrifolia, Piper latifolium, and Pipturus argenteus, with coffee flourishing and vanilla occurring occasionally as escapes. Discrete groves of bamboo (Schizostachyam glaucifolium) and mango are also found in areas of old fallow forest. Of particular importance are the widespread fallow groves of a vegetatively propagated sterile form of Hibiscus tiliaceus (H. tiliaceus var. sterilis), which was possibly an aboriginal cultigen because of its wide utility in construction and for fruitpicking poles (Decker 1971, 258-262).
In transitional or drier areas, where vegetative growth is slower, back- or up-valley gardens are maintained for longer periods of time, interspersed between uncleared areas of mid-slope forest dominated by Pandanus tectorius, Sapindus saponaria, and Xylosma suaveolens. The crops are essentially the same, although woody perennials including Canthium odoratum, Capsicum frutescens, Carica papaya, Ficus prolixa, Hibiscus tiliaceus, Morinda citrifolia, Cerbera manghas, Premna serratifolia, Psidium spp., Sapindus saponaria, and Xylosma suaveolens, are generally spared in the clearance for new gardens or protected in garden regrowth (Decker 1971, 206). On exposed uplands and ridge tops Casuarina and Pandanus groves, Miscanthus floridulus and Tricholena rosea grasslands, fern scrub lands, and scattered forest stands and thickets exist, along with occasional thickets of Hibiscus tiliaceus in more humid areas (Decker 1971, 231-232).
Thickets in transitional areas include, most commonly, Psidium guineense, P. guajava, Celastrus crenatus, Colubrina asiatica, Premna serratifolia, and Morinda citrifolia, all of these, even C. asiatica, approaching tree stature. Scattered in the widespread Miscanthus (kokaho) grasslands, which have been maintained by periodic burning since pre-European-contact times, are a number of tree species, including, most prominently, Psidium spp., as well as Morinda citrifolia, Celastrus crenatus, Pandanus tectorius, Hibiscus tiliaceus, Xylosma suaveolens, and Casuarina equisetifolia. The forest on lower canyon slopes is dominated in most areas by Xylosma suaveolens and Sapindus saponaria, which give way to Hibiscus tiliaccus in the wetter areas or to coconut groves on the lower slopes. Forests in the valley ravines and bottoms in the transitional zones include the common Sapindus saponaria and Xylosma suaveolens, as well as Hibiscus tiliaceus, Thespesia populnea, Erythrina variegata, Pisonia grandis, Pandanus tectorius, Morinda citrifolia, Canthium odoratum, Premna serratifolia, Aleurites moluccana, and occasionally Celtis pacifica, and Cordia subcordata, with large banyans (Ficus prolixa) as common large emergents. Also appearing sporadically in ravines and valleys are planted or spontaneous economic plants such as chillies (Capsicum frutescens), and kapok, orange, and coconut trees (Decker 1971, 244 245).
Most of the same species, with the exception of Cordia subcordata, Celtis pacifica, and Pisonia grandis, which are absent or uncommon away from the coast and valley bottoms, are also found in transitional forest on upland slopes and inland ridge crests, with Xylosma suaveolens and Sapindus saponaria being the co-dominants, except where the latter has been exploited for firewood for bakers' ovens. Species also found in ridge-crest areas include Glochidion sp., Canthium barbatum, Coffea arabica, occasionally Cocos nucifera, and Mangifera indica; the more frequent occurrence of Hibiscus tiliaceus; and discrete groves of Pandanus tectorius and Casuarina equisetifolia (Decker 1971, 246-252).
In the more arid zones, arborescent plants are more restricted to relict forest stands in the interior and in well-watered and sheltered ravines, with shrubby species (such as Indigofera suffruticosa) and Leucaena leucocephala invading extensive inland areas and coastal areas. Acacia farnesiana, although not invasive, persists in some areas. Other shrub and tree species found in non-garden areas include Gossypium barbadense, Jatropha gossypifolia, Cordia lutea, Tamarindus indica, and Albizia lebbeck, the latter two being occasionally planted (Decker 1971, 214-215).
Open woodland stands of Sapindus saponaria are common, with other tree species in arid areas including Celastrus crenatus, Celtis pacifica, Syzygium spp., Guettarda speciosa, Morinda citrifolia, Psidium spp., and Thespesia populnea. In areas denuded by goats, solitary banyans (Ficus prolixa) are occasionally found.
The most aggressive of the exotic plants and one of the most difficult to clear for new gardens is Leucaena leucocephala, which is controlled in some banana, cassava, and tannia gardens by deliberately planting cuttings of another aggressive weed, Commelina diffusa. After original Leucaena clearance, this weed retards further regen eration, at the same time providing valuable easily-cleared fodder for the ubiquitous horse. This is, however, not a practice in gardens with spreading ground crops such as sweet potatoes and melons, which thrive on clear cultivation and would suffer from competition from Commelina diffusa. Where Leucaena has become established, the tenacious stands seem to exclude all groundcover of other species, with little or no tendency toward succession by native or indigenous trees.
The non-arable uplands, which are dominated by Gleichenia linearis fern lands, with scattered Casuarina equisetifolia and Pandanus tectorius, are found on the deep, degraded latosols of the upland interfluves. Along with the Miscanthus floridulus grasslands, these apparently pyrogenic and fire-maintained areas serve as important seasonal grazing areas covering most of the interfluvial terrain.
The humanized forest of the Marquesas
The close examination of Marquesan plant cover offered here reveals yet again the intense humanization of many Pacific Island landscapes. Looking at the Islands' often extensive forest cover, the uninitiated would be likely to assume that the forest was largely natural, punctuated here and there by gardens or grassy ridges - a land waiting for development. Instead, the forest - much of which is a human artifact is intricately linked to the inhabitants' production of food, materials, and cash crops. The individual trees are the wheels of the forest factory, turning out a great variety of products while also working slowly together to enhance the future productivity of garden soils and to help maintain the present stability of slopes and the clarity of streams. The efficiency of this "factory" could in many instances be improved; its human managers may make mistakes; hard-to-manage components, like Leucaena, may get introduced; none the less, a forest "factory" is already operating in place. It would be useful in planning for the future welfare of land and people to recognize this factory's existence and its significance, before dismantling it under the false impression that it serves little purpose and has no connection with human activities.