| Agroforestry in the Pacific Islands: Systems for Sustainability (1993) |
|9 Institutional agroforestry in the Pacific Islands|
Grazing with commercial tree cropping and silviculture
Grazing, usually of cattle, with commercial tree cropping and silviculture consists mainly of the widespread practice of grazing cattle under coconuts or commercial timber species, and the limited grazing of cattle under Leucaena leucocephala or other fuel-wood or multipurpose species.
Livestock under coconuts
The grazing of cattle (primarily beef, but also dairy cattle) under coconuts (in some cases with pasture improvement) is by far the most widespread practice. It has been encouraged throughout the Islands since colonial times, particularly on large coconut estates. In addition to providing meat and dairy products, cattle are seen as effective weed control and fertilization agents, thus facilitating plantation management and the collection of fallen nuts.
Although primarily promoted on large, often foreign or state controlled estates or plantations, some governments, such as those in the Solomon Islands, Tonga, and Niue, have encouraged smallholder grazing of cattle under coconuts and other trees. In the case of Tonga, smallholder agriculturalists have been encouraged to fence limited portions of their 3.3 ha bush allotments to graze cattle, and sometimes horses, under coconuts and other tree crops and protected trees, or, alternatively, to tether animals to trees and graze on a rotational basis.
The practice has been particularly important in Vanuatu (both before and after independence in 1980) and New Caledonia, where beef cattle production is a major activity. Beef cattle production became so important in Vanuatu, prior to independence, that some plantations were turned into cattle properties. The importance of cattle grew in the 1950s, when steeply rising labour costs made planters increasingly dependent on cattle to keep their plantations clean. At one period in the 1950s, herds became larger than the plantations could support, especially during dry spells, and by the end of the decade, town butcheries had opened in both Port Vila and Luganville, the two main towns. By the end of the 1960s, copra production had become no more than a sideline on a number of plantations (Brookfield with Hart 1971, 164165).
In Fiji, in 1973, 10.5 per cent of the local beef requirements were supplied by the 9.9 per cent of the cattle population grazed under coconuts (MAF 1973; Manner 1983). This is particularly significant given the large proportion of range-fed cattle raised on extensive large-scale developments in the dry zones of Fiji. Papua New Guinea, the Solomon Islands, Vanuatu, and New Caledonia in Melanesia, and Western Samoa and French Polynesia have also actively encouraged cattle under coconuts with trials having been conducted on optimum stocking rates and pasture improvement. Much of the Western Samoa Trust Estates (WSTEC) Mulifanua Copra Plantation, reportedly one of the largest copra plantations in the world (Carter 1984), is undergrazed by cattle.
The potential for the formal promotion of large-scale grazing of cattle under coconuts is greatest on the larger islands of Melanesia and Polynesia. On smaller islands, such as those in Tonga and the Cook Islands, where high population densities and land scarcity make more extensive agrosilvipastoral developments less relevant, small-scale rotational undergrazing of tethered animals is more appropriate. In Nine, where population density is low because of emigration to New Zealand, there have been problems of overgrazing and lack of fodder during times of drought- for example, during the severe drought of 1977-1978, when hay had to be imported from New Zealand.
Richardson (1983, 59) cautions that grazing under coconuts can create problems of soil compaction and, especially in the case of free grazing, preclude intercropping, which should take precedence in areas with limited land resources. As shown by studies in Papua New Guinea and elsewhere, smallholder beef cattle production can have harmful impacts on subsistence cropping (Grossman 1981). Where cash cropping or subsistence production is feasible, Richardson (1983, 59) argues that intercropping should take precedence over grazing under coconuts.
Cattle under timber species
The grazing of cattle under commercial timber species has been actively promoted in Papua New Guinea, the Solomon Islands, Vanuatu, and Fiji. In Papua New Guinea, reforestation projects in both the highlands and lowlands offer opportunities for beef production, and cattle have been actively promoted to control weeds and reduce fire danger by consuming the fuel. Pinus caribaea planting has also been encouraged in order to provide shade for cattle in open grasslands (Watt 1980, 308). The introduction of pasture legumes into timber plantations and surrounding areas has also been actively encouraged, and the development of pastures, followed by grazing, has been more or less standard practice in a number of forest plantations in Papua New Guinea, where klinki and hoop pine (Araucaria spp.), Pinus caribaea, and Eucalyptus spp. are grown. Government forest plantations are made available to local Braziers who establish adequate fencing and pastures and follow acceptable range management and stocking practices (Howcroft 1974; 1983).
In the Solomon Islands, where there is a "Cattle Under Trees" (CUT) project, cattle have been grazed under Eucalyptus deglupta in forest plantations established by the government in logged forest (Macfarlane and Whiteman 1983; Schirmer 1983, 101; Watt 1980, 308) and in Vanuatu under both "Local Supply Plantations" and "Industrial Supply Plantations" of Cordia alliodora, as well as under Pinus caribaea on Aneityum, Erromango, Pentecost, and Santo (Jacovelli and Neil 1984, 8). Grazing under pines in Vanuatu is seen as a means of reducing the significant fire threat in plantations (Neil 1986a).
It is in Fiji that the practice has probably been tried most exten sively, owing to research undertaken by the Fiji Pine Commission (FPC), a statutory body with the objective of facilitating and developing "an industry based on the growing, harvesting, preserving and marketing of pine and other species of trees grown in Fiji" (CPO 1980, 141). The FPC is responsible for managing over 45,000 ha of Pinus caribaea out of an envisioned gross estate of 80,000 ha on the highly degraded talasiga (sunburnt) soils of the drier leeward grasslands of the two largest islands of Fiji. The relatively infertile and eroded areas are vegetated with a grassland sub-climax of presumed anthropogenic origin, including species such as Pennisetum polystachyon, Pteridium esculentum, Gleichenia liners, Psidium guajava, Dodonaea viscose, and Casuarina equisetifolia. On moister slopes, Miscanthus floridulus forms almost impenetrable thickets. These grasslands are subject to frequent and unauthorized burning.
The FPC undertook research into cattle grazing for two reasons: to examine the effects of cattle grazing on reducing fuel in high fire-risk zones; and to test the use of cattle as a site-preparation tool for clearing the land of Miscanthus floridulus, which proved difficult to eradicate by more conventional means such as slashing and burning (Drysdale 1982). Research has yielded variable results. Vincent (1971) concluded that grazing of cattle under 5- and 6-year-old pine plantations in poor soils had a detrimental effect on the incremental growth of pines, whereas grazing trials in the Nausori Highlands to determine the effect on fire hazard reduction resulted in a reduction in fuel from 2,500 kg per hectare to 800 kg per hectare, an average cattle weight gain of 0.24 kg per day, and no pasture deterioration despite heavy stocking rates (Gregor 1972). At Nawaicoba, Partridge (1977) reported weight gains twice this, when trees were planted at 2 m x 3 m spacing, with two rows in every five missing. In variable spacing trials, Bell (1981) found slight bark damage to trees less than one year old because of trampling, when the trees were spaced 3 m apart within rows and 2.5, 3, 3.5, and 4 m apart between rows, the cattle being introduced into the plantation when the pines were 54 cm high.
In 1982, the FPC reviewed various research projects on cattle under pines and concluded that given "the high overhead and general costs of FPC operations, commercial cattle grazing of unimproved pasture under pines, is an unlikely prospect" (Drysdale 1982, 4). Although fuel loadings were considerably reduced, the cost of using cattle for fuel reduction was "considered unacceptably high compared with alternatives such as burning" (Drysdale 1982, 3). In contrast, the use of cattle as a site-preparation tool where Miscanthus predominates was termed an "outstanding success" (Drysdale 1982, 8) because other methods of clearing the giant grass gave incomplete results, were impractical, or cost too much.
Because of the high cost of fencing, the long-term and extensive grazing of cattle under pines has been found to be an uneconomic proposition for the Fiji Pine Commission, although some 480 cattle are allowed to graze under pines free of charge at Drasa and Tavaka-bo, and some cattle owners unofficially graze their cattle in Fiji Pine Commission forests. Native landowners are also allowed to graze cattle under their own pine plantings, subject to certain restrictions. But cattle owners also are unlikely to find fencing a profitable venture. Open-range grazing with night-time penning may be a possibility. In addition, the economics of cattle grazing on improved pastures under trees in Fiji still needs to be ascertained.
Other silvipastoral activities
Trees such as Leucaena leucocephala are used as fodder in Tonga and Papua New Guinea, where they are browsed by cattle as a dietary supplement (Watt 1980, 308). There is perhaps some scope for the grazing of other animals such as pigs, goats, and chickens on improved legume pastures or fallows under coconuts, commercial timber species, or other trees (Quartermain 1980; Richardson 1983).