Overstory #49 - Traditional Pacific Island Agroforestry Systems
Agroforestry was traditionally practiced in many parts of the tropics. Most traditional agroforestry species and techniques have not yet been subject to institutional scientific experiments. However, they have been well-tested by local farmers, often over many generations. These traditional systems and species can provide a strong, locally-based framework for future agroforestry development. Indigenous knowledge systems are now being regarded as an invaluable resource.
In this issue of The Overstory, guest author Dr. Randy Thaman highlights three traditional agroforestry systems from the Pacific Islands.
Traditional Pacific Island Agroforestry Systems
Trees have always been important to Pacific Island societies. Pacific Island peoples planted and protected trees as a part of their multi-species and multipurpose agroforestry and land use systems. They have also been willing to accept new trees that can make their life and their island environments better. Traditional Pacific Island agricultural and land use systems were agroforestry systems, built on a foundation of protecting and planting trees. These systems made Pacific Islanders among the most self-sufficient and well-nourished peoples in the world.
Future agroforestry development in the Pacific Islands would do well based on the conservation, strengthening, and expansion of the many time-tested multipurpose agroforestry species and systems that already exist in the Pacific Islands. The emphasis on the protection, as well as the planting, of these species is of utmost importance. Experience has shown that it is far more difficult to replace forests, agroforests, trees, and rare cultivars of trees (e.g., breadfruit, coconut, pandanus and banana cultivars), than it is to protect what already exists. Minimizing the loss of knowledge about these systems and species is also essential.
Pacific Island agroforests were developed and managed to meet not only people 's needs for food and other products, but also the needs of the system as a whole for fertilizer, mulch, animal food, shade. The trees in the system also provide protection from erosion, wind, and salt spray.
Tongan Agroforestry Example
In Tonga the multispecies agroforestry system is a very complex mixture of trees, shrubs, and short-term ground crops. It is usually practiced as a short-term shifting agriculture system on pieces of land averaging eight acres or less in size. When the land is prepared for a new garden, some of the fast-growing pioneer tree species, most shrubs, and grasses are cut and allowed to dry. The dried material is then placed in piles for burning. Other valuable trees that are present in the fallow, such as breadfruit, mangoes, avocado, citrus trees, Malay apple (Syzygium malaccense), Polynesian plum (Spondias dulcis), perfume tree or ylang-ylang (Cananga odorata), and, of course, coconut palms, are protected or, in some cases, slightly pruned to allow the sunlight to enter the garden area. Other culturally important trees, like koka (Bischofia javanica), Pacific litchi (Pometia pinnata), maululu (Glochidion ramiflorum) and toi (Alphitonia zizyphoides) are then pruned, often by cutting almost all of the branches off. This practice does not kill the tree, and accomplishes a number of objectives. It allows the entry of sunlight needed by the first crop to be planted, which is usually yams (Dioscorea alata). It also allows the leaves to fall providing organic material to the soil, and allows for fresh new branches to grow as the garden matures. The larger branches that have been cut from the trees are used as trellises over each yam mound. Yams climbing off the hot volcanic soils on these trellises have higher yields, are more disease free, and are more easily weeded. Because Tonga has frequent serious tropical cyclones (known elsewhere in the Pacific as hurricanes or typhoons), the lower trellises are much more appropriate that the higher trellis on poles used in other countries. Finally, when the yams are harvested, after 7 to 9 months, the branches make perfect firewood for the underground oven.
In the garden, the yams are usually intercropped with rows of giant taro (Alocasia macrorrhiza), plantains (Musa cultivars), and taro (Colocasia esculenta). Along the borders, sweet yams (Dioscorea esculenta) are often planted next to the fenceposts, and pandanus for weaving, sugarcane or bush hibiscus spinach (Abelmoschus manihot), a very important leafy green vegetable, are often planted along the borders or fencelines of the garden. The living fencing will often be candelnut tree (Aleurites moluccana), beach hibiscus or fau (Hibiscus tiliaceus) or dadap or ngatae (Erythrina variegata). In some cases, timber trees, such as casaurina (Casuarina equisetifolia) or introduced species, such as Australian kauri (Agathis robusta) or West Indian mahogany (Swietenia macrophylla), are planted in a few rows along the perimeter or along the roadside border of the allotment, or sometimes as a small woodlot on part of the allotment. Other short-term crops such as green onions (Allium fistulosum and A. ascalonicum), Chinese cabbage or paak tsoi (Brassica chinensis), and corn (Zea mays) are often planted systematically, or bird-sown chili peppers (Capsicum frutescens) are protected in the garden.
After the yams are harvested, taro or tannia (Xanthosoma taro) is planted as the next crop in the soft soil left over after the yam harvest. The giant taro and taro that were planted with the yams are then harvested. The second crop of taro or tannia and the bananas remain. When this crop is harvested, sweet potatoes or cassava are then planted, and if sweet potatoes are planted, another crop, usually cassava is planted which completes the three to four-year shifting agricultural cycle. Sometimes, the cycle is extended for a further three to five years by planting kava (Piper methysticum), the important social beverage plant, or paper mulberry (Brousonnetia papyrifera), so important for the making of tapa cloth used in Tongan ceremonies and to sell to tourists and for export. As the garden is allowed to slowly return to fallow for four to up to ten years, the plantains continue to bear fruit, the fruit trees and other multipurpose trees continue to provide food, medicines, and other products.
Marquesan Agroforestry Example
Homegardens in the Marquesas Islands of French Polynesia are characterized by a great diversity of mainly exotic plants that have been introduced during some 1,500 years since the first arrival of humans to the islands. Many of these plants have been added since European contact. Dominant species include the important staple food trees coconut, breadfruit, mango and kapok (Ceiba pentandra) which are both very common, and the ubiquitous beach hibiscus tree (Hibiscus tiliaceus) which forms part of the backdrop of every village. Common spreading ornamental shade trees include the rain tree or monkeypod (Albizia saman) and the flame tree or poinciana (Delonix regia), with Albizia lebbeck also present in dwelling areas.
Home gardens also include a wide variety of staple plants and important fruit trees. These include banana cultivars, mango, papaya, lime, avocado, soursop and sweetsop (Annona muricata and A. squamosa), guava, and tamarind. Sugar cane is also common. The cultivated pandanus (Pandanus tectorius var laevis), so important in the production of plaited ware, and kapok are also common in home gardens. Ornamentals planted as hedges or along borders, which are commonly used for garlands and fragrant flowers include Gardenia taitensis, ylang-ylang (Cananga odorata), the common hibiscus (Hibiscus rosa-sinesis), an the hedge panax (Polyscias guilfoylei).
Immediately surrounding dwelling areas and in uncared-for places on the islands of Nukuhiva ad Uapou, are extensive stands of Leucaena leucocephala. These stands of trees provide the main source of 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.
Kiribati Atoll Agroforestry Example
Coconut palms, usually of a number of different varieties, are planted as a major cash and multipurpose crop. Sometimes they are planted in rows and sometimes allowed to grow in irregular patterns. Other multipurpose trees, such as screw pine (Pandanus species), Guettarda speciosa, Tournefortia argentea, and the shrub Sida fallax (te kaura in Kiribati or ilima in Hawaii) are protected, or sometimes planted to provide soil improvement and leaves or mulch (fertilizer) for the swamp taro (Cyrtosperma chamissonis) pits that have been excavated down to the water table. The pandanus is also a very important staple food plant on the atolls, as well as being the source of timber for house building, thatch, fibre for mat and basketmaking, medicines, and many other products. Because of the many uses that the people of Kiribati have for the pandanus tree, they have been referred to as the "Pandanus People." Breadfruit, papaya, native fig (Ficus tinctoria), and sometimes bananas and true taro (Colocasia esculenta) are also planted in or around the taro pit. The coastal forest on both the ocean and lagoon sides of the garden area, and the mangroves on the lagoon side, are protected to shelter the inland plantation from salt spray, high waves, extremely high tides, and from coastal erosion. The protection of these forests, and the protection of the other trees also ensures that the wood, medicine, and many other products provided by the trees and forests are still available. This practice also ensures the continued availability the fish, shellfish, crabs, birds, and other animals and small plants that depend on these forests and trees will be protected for future generations.
A traditional agroforestry system represents a long-term investment of time, knowledge, and effort in a living, growing, "bank account." If protected and improved, traditional agroforestry is a time-tested (for thousands of years) foundation for future development. It can help to ensure that the needs of future generations of Pacific Islanders will be satisfied.
About the Author
Dr. Randy Thaman is Professor of Pacific Island Biogeography at the University of the South Pacific, Suva, Fiji. He also serves as chairman of the Fiji National Food and Nutrition Committee. Thaman is the author of several important books, including Agroforestry in the Pacific Islands: Systems for Sustainability. His research includes Pacific Island agriculture, agroforestry, food systems, and ethnobotany.
A very useful treatment of agroforestry practices in the Pacific, including lists and descriptions of many agroforestry species, can be found in the book: W.C. Clark, R.R. Thaman (Editor), Agro-Forestry in the Pacific Islands: Systems for Sustainability. 1994. Unipub.