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close this bookAgroforestry in the Pacific Islands: Systems for Sustainability (UNU, 1993, 297 pages)
close this folder7 Pacific Island urban agroforestry
View the document(introduction...)
View the documentHome-garden urban agroforestry
View the documentUrban agroforestry on undeveloped land
View the documentProblems of urban agroforestry
View the documentIntegrating agroforestry into urban planning and policy

Home-garden urban agroforestry

Urban agroforestry in home gardens is today a ubiquitous feature of urban landscapes in the Pacific Islands. Even in areas not renowned for agricultural diversity, such as Kiribati and Nauru, urban gardens contain a wide range of food trees, non-tree staple and supplementary food plants, and non-food plants (table 8). Cultivation or protection of trees and non-tree plants on idle or undeveloped land in urban areas is also very widespread and provides an important source of other produce, including limited commercial production (Thaman 1977a; 1977b; 1984a; 1985a; 1987a; 1988e).

As suggested by table 8, more than 20 species of trees are common in the "food trees" category in urban agroforestry gardens. Also common are all the important staple root crops and a great range of supplementary non-tree food plants such as onions, amaranths, pineapple, peanuts, cabbages, a wide variety of legumes and "spinaches," cocurbits, okra, tomatoes, passion-fruit, sugar cane, eggplant, and corn. There are also condiments and spices such as chillies, ginger, coriander, and mint as well as plants producing beverages, stimulants, and depressants (betel-nut, betel pepper, kava [Piper methysticum], tobacco, and lemon grass). Many of the home gardens surveyed contained a large proportion of these plants.

Table 8 Number of species and distinct varieties found in surveys of urban agroforestry systems in Port Moresby in Papua New Guinea; Suva in Fiji; Nuku'alofa in Tonga; South Tarawa in Kiribati; Nauru; and Location, the contract-worker settlement in Nauru

Crop types Papua New Guinea Fiji Tonga Kiribati Nauru Location
Food trees 30* 39 27 20 14* 16
Non-tree staples 7 10 8 6 5 8
Non-tree supplementary foods 48 65 44 35 14 41
Total 85 114 79 61 33 65

*The totals for Papua New Guinea and Nauru would have been slightly higher for food trees if Musa clones and Citrus spp., respectively, had been differentiated.

As stressed by Soemarwoto et al. (1985, 44), in their study of Javanese home gardens, true plant diversity is far greater than indicated by the presence of many different species since many species are represented by numerous cultivars. In Tonga, for example, there are numerous distinct, named breadfruit cultivars. And in tree gardens in settlements in Yap, as already mentioned in the section on the Micronesian high islands, there are 21 named coconut cultivars, 28 breadfruit cultivars, and 37 banana cultivars (Falanruw 1985, 16). There is similarly great cultivar diversity among other crops such as mangoes, domesticated Pandanus, papayas, and especially among the traditional staple ground crops such as yams, taros, and sweet potatoes. This intra-species diversity adds economic, ecological, and nutritional stability to urban agroforestry systems.

"Weed" species are also myriad in urban agroforestry gardens, but as Soemarwoto et al. (1985,44) caution, "the term 'weed' should be used with extreme care" because of the many uses home gardeners have for weeds - as medicines, fodder, mulch, roofing, fish poisons, toothbrushes, and vegetables. "Weeds" such as Amaranthus spp., black nightshade (Solanum nigrum), purslane (Portulaca oleracea), and water spinach (Ipomoea aquatica), for example, are important pot herbs in Fiji and are often sold at the Suva Municipal Market (Thaman 1976/77), and almost all grass species are used for fodder.

Food trees

Although staple ground crops are most numerous, food trees such as coconut, breadfruit, papaya, Citrus spp., mango, Musa clones, guava, Annona and Syzygium spp., avocado, Tahitian chestnut (Inocarpus fagifer), hog plum, or vi-apple (Spondias dulcis), oceanic lychee (Pometia pinnata), and Terminalia spp. are the dominant plants of most urban landscapes, especially in long-settled areas. An exception would be Location, the indentured worker settlement in Nauru, where little or no space for gardening exists, let alone tree cropping, and where a high proportion of plants are grown in artificial boxed beds or containers. The only mature trees are bananas and scattered coconut palms.

Trees constitute a particularly important economic and nutritional resource on low-lying islands such as the atolls of Kiribati, where apart from giant swamp taro (Cyrtosperma chamissonis), which is generally reserved for special occasions, the main staples are all tree crops: coconut, breadfruit, Musa clones, pandanus, and the native fig (Ficus tinctoria). Trees are, nevertheless, very important in home gardens on high islands as well. For instance, as described in chapter 6, the tree gardens around homesteads in Yap contain some 50 species of introduced or indigenous food trees (Falanruw 1985, 15-16). Trees of particular importance to the Indian population of Fiji (who currently make up close to half of Fiji's population) include jakfruit (Artocarpus heterophyllus), horseradish, or drumstick tree (Moringa oleifera), curry leaf, or Indian bay (Murraya koenigii), and tamarind (Tamarindus indicus).

Staple crops

The most common staples include the important root crops, such as cassava, taro, sweet potato, and tannia (Xanthosoma spp.), with giant taro (Alocasia macrorrhiza) important in Tonga, and giant swamp taro (Cyrtosperma chamissonis) particularly important in the harsh environment of the lowlying atolls of Kiribati, as discussed in the previous chapter (Thaman 1984b).

True taro (Colocasia esculenta) is particularly well suited to urban conditions because it can be grown on small plots, either as a staple for its corms or for its leaves, which constitute the most common leafy vegetable, or "spinach," in many areas. It is often found planted in wet conditions along drains, near water taps, or washing areas (Thaman 1977a; 1977b).

Cassava is commonly planted in back and front home gardens in Suva and Port Moresby and along road frontages in Suva, and sweet potatoes commonly occupy large proportions of back and front home gardens in Port Moresby, as well as being found in small plots around homes in densely-settled urban Tarawa. Tannia (Xanthosoma) is also of increasing importance as it seems to be disease-resistant, relatively drought-resistant, and grows well in the shady conditions commonly encountered in older urban areas where mature trees dominate the environment.

Supplementary food crops

Supplementary crops, such as hibiscus spinach (Hibiscus manihot), Amaranthus spp., pineapple, cabbages, chillies, taro (grown especially for its leaves), cucurbits, tomatoes, sugar cane, and a wide variety of edible legumes, are also very common in urban gardens throughout the Pacific. These, plus a wide range of other supplementary, often shortterm crops, constitute a valuable nutritional and economic resource.

Non-food plants

In addition to plants for food, drink, or supplementary consumption, many useful non-food plants are also found in home gardens. These include handicraft plants such as Pandanus spp., used in plaited ware, paper mulberry (Broussonetia papyrifera), used for bark or tape cloth, and annatto (Bixa orellana) and Bischofia javanica (both sources of dyes); Leucaena leucocephala, an important renewable fuel-wood resource; a great range of medicinal plants, many of which are trees; plus many other plants with a variety of uses.

Medicinal plants have long been of significance and remain a resource, given the high cost of imported medicines, not to mention their frequent unavailability, misuse, and, in some cases, doubtful efficacy. In Fiji, where extensive areas of tropical rain forest, coastal strand, and mangrove forest still exist, 40 per cent (73) of 183 plant species reportedly used medicinally by the indigenous Fijians (Weiner 1984) are found in home gardens in a cultivated, protected, or weedy state. On the smaller, more densely-populated islands of Tonga and Kiribati, where less natural vegetation remains, approximately 75 per cent of all reported medicinal plants (56 of 77 and 33 of 44 respectively) are found cultivated or protected in home gardens (Luomala 1953; Thaman 1976; Weiner 1971). In Nauru, where over 70 years of open-cast phosphate mining and widespread bombing during World War II have devastated most of the natural and much of the traditional cultural vegetation (Manner et al. 1984; 1985), 28 (85 per cent) of 33 reported medicinal plants are now found in Nauruan home gardens.

Of the 93 medicinal plant species found in urban gardens in these four countries, 51 (55 per cent) were trees and another 10 were woody shrubs. It should be noted that the totals for medicinal plants in Fijian urban gardens would undoubtedly be much higher if data on Indian medicinal plants were also available.

The importance of sacred or perfumed plants to urban agroforestry is also considerable. Of some 49 plant species considered by Tongans to be sacred ('akau kakala), 36 were found present in a survey of home gardens in the capital of Nuku'alofa. Twenty-three of the 36 are trees and five others are woody shrubs. In addition to their sacredness, such plants constitute a very significant economic resource. Their flowers, leaves, fruits, and bark are used in leis and ornamentation for the expanding tourist industry, as well as being the main scents used in body oil (coconut oil), perfumes, and deodorants, the imported substitutes for which are extremely expensive and often not as culturally acceptable. Many of these plants, such as heilala (Garcinia sessilis), langakali (Aglaia saltatorum), feta'u (Calophyllum inophyllum), and sandalwood (Santalum yasi), are chiefly kakala, kakala hingoa, which are reserved for nobility or very special occasions and constitute a very important and sacred cultural resource (Thaman 1987a).

Evidence from Fiji, Kiribati, and Nauru indicates that sacred and perfumed plants are of similar importance there. In Kiribati, for example, where cash incomes are very low, headbands and garlands (primarily from flowers grown in home gardens) are widely sold (often by school children to help their families) to people to wear during work or for dances and other festivities.

Similar analyses of urban agroforestry systems for other plants that yield firewood, dyes, livestock feed, insect repellents, handicrafts, fish poison, etc., would yield equally impressive lists of plants and uses.

Characteristics of urban agroforestry gardens

The commonest plants in the inventory of Pacific urban agroforestry tend to be natives or pre-European introductions, except where the gardeners are from immigrant populations. For example, the Indian population of Fiji prefers species such as eggplant, okra, Amaranthus spp., a wide range of pulses and cucurbits, and tree crops, such as jakfruit, tamarind, mango, Citrus spp., curry leaf (Murraya koenigii), Sebesten plum (Cordia dichotoma), horseradish, or drumstick, tree (Moringa oleifera), and the spiritually and medicinally important neem (Azadirachta indica).

Also of importance, however, is a range of more recently introduced crops, including temperate vegetables, pineapple, papaya, avocado, guava, and improved citrus varieties and banana clones, as well as cassava, which is a ubiquitous staple in most Pacific Island towns (Thaman and Thomas 1985). In fact, Pacific home gardens seem to have been, and will probably continue to be, one of the most effective avenues for the introduction and acceptance of new plant species.

A great diversity exists in the actual area under food crops and in their spatial distribution. Whereas some households have only a few scattered fruittrees and vegetables, many cultivate food crops on over 50 per cent of their allotments. In Port Moresby, for example, in low-income areas settled by migrants, such as Morata and Gerehu, an average of approximately 40 per cent of 450 sq m allotments were under food crops. Similarly, in some cases in Nuku'alofa, up to 75 per cent of 500-1,000 sq m allotments were under food cultivation, mainly root crops, such as taro, tannia, and cassava, amongst Musa spp. and scattered trees. Trees become increasingly dominant in longsettled areas, as cash incomes increase, soils decline in fertility, and tree seedlings mature and increasingly shade garden areas.

Ornamentals are commonly planted closest to the home, often in the front, whereas medicinal plants, sacred or fragrant plants, and other culturally valuable, commonly multi-purpose plants, are scattered amongst the food plants.

In the atoll environment of South Tarawa, Kiribati, where the cal careous soils are poor and thin and population densities are very high, traditional staple tree crops, such as coconut, breadfruit, pandanus, the native fig (Ficus tinctoria), and, in some cases, Musa spp., are predominant. In the gardens of the indigenous Nauruans (who, as a result of phosphate mining royalties, have among the highest per capita incomes in the world), ornamental, fragrant, and medicinal plants dominate, along with the ubiquitous coconut, edible pandanus, some Musa spp., and breadfruit.

At the Location contract-worker settlement, where people live in multistorey tenements, and where family gardening is limited to no more than 1530 sq m, most families have only a few plants. In the case of the gardens of Tuvaluans (nationals of Tuvalu, formerly known as the Ellice Islands) and IKiribati, they often constitute juvenile tree seedlings, staple root crops, or a single coconut or stand of bananas.

In the case of gardens made by Chinese (mostly recruited from Hong Kong) and Filipinos, the emphasis is on intensive vegetable gardening, often in containers, reflecting a more intensive system than that practiced by most indigenous Pacific peoples. In Kiribati and Tonga, however, recent emphasis has been placed by the governments and non-governmental organizations on more intensive types of gardening, such as hydroponic techniques in Kiribati because of the highly calcareous and sandy soils there. In Kiribati, where vitamin-A deficiency-induced night blindness and xerophthalmia have become problems, the planting and consumption of the vitamin-rich leaves of two native tree species, Morinda citrifolia and Pisonia grandis, have been encouraged in urban areas.