|Agroforestry in the Pacific Islands: Systems for Sustainability (UNU, 1993, 297 pages)|
|3 Agroforestry in Melanesia: Case-studies from Papua New Guinea and the Solomon Islands|
With a population density of 14.2 people per sq km in 1976, the island Malaita was (and remains) one of the more densely populated provinces of the Solomon Islands (Solomon Islands Government 1979). While more than 68 per cent of all rural Solomon Islands adults were fully engaged in subsistence or semi-subsistence agriculture and another 23 per cent were partly so engaged, comparable figures for Malaita were 77 per cent and 17 per cent respectively (Eele 1978). On Malaita, only 1,467 people were employed wageearners; most Malaitans gained their livelihood through subsistence fishing, shore and reef gathering, and shifting agroforestry. The pressures, however, for increased cash income through smallholder cattle ranching and cocoa and copra production were having a significant impact on the sustainability of shifting agroforestry on Malaita. This was readily apparent at Buma, a coastal village of approximately 361 Kwara'ae-speakers, located approximately 9 km north of Auki, the provincial capital.
The systems of shifting agroforestry at Buma, and throughout much of Malaita, are not unlike the ago-paka and ago-male systems of Kologhona, except that burning is a characteristic feature of all Buma systems. Almost all shifting agroforestry is practiced on well-drained lowland rain forest or secondary forest fallows, on both steep and level terrain. Selection of garden sites is determined by distance from the village and older gardens, availability of adjacent or nearby fallows for future plantings, soil and fallow characteristics, and previous productivity of the site (Manner 1980). New gardens are usually located adjacent to producing gardens, which serve as sources of planting materials for the new gardens. The old gardens are thus extended in a style resembling the linear arrangement of gardens described by Oliver (1955) and Connell (1978) on Bougainville.
Both men and women participate in gardening activities such as slashing the undergrowth, transporting planting materials, burning, planting, and weeding. Men are usually responsible for the more arduous tasks such as tree felling, log removal, and their emplacement as boundaries. All trees except Areca catechu, Artocarpus altilis, and Canarium indicum are cut down by axe. After a drying period of 1-2 weeks, the litter is gathered into small piles and burned. If young (5-12 years) secondary forest is cut for gardening, the Buma Kwara'ae ensure that all parts of the garden receive ash. On the other hand, if mature secondary forest or rain forest is felled, the regrowth is slashed and the litter burned - although little is done to ensure that all parts of the garden receive ash.
The cleared plot is marked off into sections, then a dibble stick is used to plant a wide variety of root-crop cultivars, fruit and nut trees, and other crops such as pineapple, water melon, Hibiscus manihot, tomatoes, and tobacco (table 4). Newly cleared gardens (2-4 months old) are dominated by taro (Colocasia esculenta), giant taro (Alocasia macrorrhiza), and the sweet or lesser yam (Dioscorea esculenta). As taro and other cultigens mature, replanting is carried out. By way of contrast, older gardens are dominated by Alocasia macrorrhiza, pineapple (Ananas comosus), sweet potato (Ipomoea batatas), and a heavier weed cover. The gardens are abandoned to fallow two years after initial planting.
This human-directed succession of cultivars and the release of gardens to fallow can be seen as a reflection of Kwara'ae understanding of crop requirements and ecological processes. The presence of sweet potatoes and cassava in older gardens indicates poorer soil fertility a condition to which these species are adapted (Haynes 1977; Thaman 1976; Thaman and Thomas 1982, 1985). Bananas and other tree and shrub crops, because of their height and longer growth cycles, may be better adapted to resist the increased weed and pest in festations of older gardens. Their more extensive rooting systems may also be more efficient in nutrient uptake than shorter-lived plants. Finally, as the fallow period continues, there is the increasing regeneration of pioneering forest trees, which brings renewed fertility and filth and increases habitats for other forest-dwelling organisms. Wild food products multiply and noxious garden pests disappear. In addition, the mixed forest is the source of building materials, medicines, dyes, and food; and its regeneration may help to maintain the cultural and economic stability of the Buma Kwara'ae. Major tree or tree-like species include a range of bananas and plantains (Musa cultivars), the culturally important betel-nut (Areca catechu), the ngali nut (Canarium indicum), papaya (Carica papaya), and the nutritious hibiscus spinach (Hibiscus manihot) (table 4).
Monetization and agrodeforestation
For the past two decades, the sustainability of the Kwara'ae shifting agroforestry system has been threatened by government-sponsored smallholder cattle, cocoa, and copra projects, and by sweet potato cashcropping for the Auki market. The resultant agrodeforestation brought about by the increasing emphasis on cash cropping has greatly increased pressures on Buma land resources and caused the spatial displacement of traditional agroforestry, a process noted as occurring elsewhere by Chapman and Pirie (1974) and Quartermain (1980). At Buma, cocoa is intercropped with coconuts, and cattle are grazed under coconuts and other valuable tree species. Prior to these introductions, the Buma Kwara'ae practiced traditional agroforestry on lands classified as "highly suitable agricultural opportunity" areas (Wall and Hansell 1974), and which were located within 15-30 minutes walking time from the village. Today, however, most traditional agroforestry is practiced on more distant and steeper-sloping lands. Walking times to these areas range from 30 to 60 minutes. Unfortunately, the burden of transporting garden produce, which may weigh as much as 15 kg per trip, often falls on the women. The Buma Kwara'ae have potential gardening sites located 2 hours farther inland, but few gardens have been cleared in these relatively distant areas. It is ironic that a major reason for this decline in traditional agroforestry is narrowly focused, institutional smallholder agroforestry focused primarily on the tree crops, cocoa and coconuts.
Similarly, cash cropping of sweet potatoes for the Auki market has also displaced traditional agroforestry farther inland. Moreover, this cash cropping is conducted in forest or bush fallows often less than 3 years old. This shortening of the gardening cycle has led to significant soil deterioration and a retrogression of the fallow vegetation from the useful arboreal species that characterized traditional forest fallow to a community dominated by Acalypha grandis, ferns, and Imperata cylindrica.
Table 4 Species composition of Buma village gardens, West Kwara'ae, Malaita, the Solomon Islands. (Data expressed as number of plantings per 5m x 5m quadrat; C =cormels; D = dominant crop)
|Garden age||2-4 months||6-12 months||12-18 months||18+ months|
|Scientific name (Kwara'ae or common name)|
|Alocasia macrorrhiza(giant taro)||2||5||5||5||19||19||2||4||3||12||3|
|Ananas comosus (pineapple)||4||6||9||5||7||3||2|
|Areca catcheu (betel-nut)||1|
|Canariurn indicum (ngali nut)||1|
|Carica papaya (pawpaw)||11||1|
|Colocasia esculenta (taro)||38||42||2||2||15||13C||2C||2C||7C||15C|
|Citrullus lanatus (water melon)||2||1|
|Dioscorea esculenta (sweet yam)||16||17|
|Hibiscus manihot (hibiscus spinach)||5||1||1||2|
|Ipomaea batatas (sweet potato)||10||5||D||D||D||D||9D||D||D||D||D|
|Lycopersicon esculentum (tomato)||1||1|
|Manihot esculenta (cassava)||4||2||9|
|Musa cultivars (banana/plantain)||2||1|
|Nicotiana tabacum (tobacco)||1||2||1||2|
|Number of species||5||3||4||5||2||5||5||3||4||5||3||6||2||2||5||3|
Source: Adapted from Manner 1980.