Madagascar dominates the sub-region in terms of land mass, occupying nearly 600 000 km2, the fourth largest island in the world. The remaining countries are made up of archipelagos of between 3 and 115 islands, with a combined size of 2 000 km2. Large parts of the western Indian Ocean Islands are mountainous, rugged and dry, and unsuitable for cultivation. Only Madagascar is large enough to support a significant amount of permanent pasture (41 per cent of the land area) and livestock production (UNEP 1999b). The dominant land use in the sub-region is cultivated crops in Comoros and Mauritius (40 and 48 per cent of the land area respectively), whilst all countries have significant cover of forests and woodlands, which are widely used for grazing and gathering of wild resources (UNEP 1999b). Most of the islands experience monsoon rains from November to April, and total rainfall varies from island to island, within the range 700 mm/yr to more than 2 000 mm/yr. Cyclones are also common in some of the islands, and this can be highly erosive to exposed soils. By contrast, dry spells and droughts are not uncommon, especially in southern Madagascar.
Agriculture is an important activity in the Western Indian Ocean islands, both at the subsistence level and at the commercial level. The major commercial crops are: bananas; cassava; cloves; coffee; copra; onions; potatoes; rice; sugar; sweet potatoes; tea; vanilla; and ylang ylang, a perfume which is unique to Comoros. In 1970, agriculture employed 83 per cent of the workforce in Comoros, 84 per cent in Madagascar and 34 per cent in Mauritius. This fell slightly in all countries over the following two decades, with Mauritius showing the greatest decline, to 17 per cent by 1990 (World Bank 2001). Over the past 30 years, the agricultural sector has also contributed significantly to the economies of the sub-region's countries, with the result that the best land has been reserved for the commercial production of luxury commodities, and the countries are net importers of cereals and staples.
In Comoros, the contribution of agriculture to the economy has ranged from 35 per cent to 38 per cent of GDP between 1980 and 1999 (World Bank 2001). In Madagascar, the contribution to GDP has been slightly lower, at between 24 and 28 per cent (World Bank 2001). In the Seychelles, agriculture's contribution to GDP has fallen from nearly 10 per cent in 1980 to less than 5 per cent in 1999, as tourism has grown in income contribution and foreign exchange earnings (World Bank 2001). Exports from agriculture in 1999 were estimated at US$92 million from Madagascar, and US$405 million from Mauritius (World Bank 2001).
Subsistence agriculture is practised on all islands in the sub-region, especially in Madagascar and Comoros, where slash-and-burn agriculture is a common means of supplementing household food requirements and incomes. However, due to economic pressures for agricultural exports and foreign exchange earnings, the best land is often reserved for commercial crop production (especially sugar, copra, vanilla, coffee and ylang ylang) (UNEP 1999b). As a result of rising population pressure and of increasing demand for land for subsistence farming, more natural habitat is being converted to cultivation, and the soils are becoming degraded, especially in the marginal areas, where lowinput subsistence agriculture is practised. As a result, there are signs of reduced productivity compared to levels 50 years ago (UNEP 1999b).
These same pressures have resulted in increased area of land under cultivation in Comoros (from 90 000 ha in 1970 to 120 000 ha in 1999) and in Madagascar (from 2 300 ha in 1970 to 3 100 ha in 1999). In Mauritius and Seychelles, the area of land under cultivation has remained fairly constant (at 100 000 ha and 5 000 ha respectively) and, in Reunion, the area of cultivated land has actually declined slightly, from almost 60 000 ha to less than 40 000 ha (FAOSTAT 2001).
Although absolute food production indices have also climbed over the past 30 years, as a result of population growth and largely export-driven markets, food production per capita has declined in all countries, as shown in Figure 2f.10 and Figure 2f.11 (FAOSTAT 2001). In Madagascar, where there is significant rearing of livestock, production indices have also risen, by almost 50 per cent of the output in 1970 but, again, this has been outstripped by population growth, and per capita production rates have fallen by almost 40 per cent (FAOSTAT 2001). In Mauritius, livestock rearing and processing, principally chicken farming and fish farming, has produced an increase in food production (UNDP 2000).
The gap between food production and population growth, and the emphasis on commercial agriculture rather than production for domestic consumption, have resulted in a food deficit, particularly in cereals and other staples (FAO/GIEWS 1998). As a result, some countries, such as Mauritius and Seychelles, import significant quantities of cereals, whereas Comoros and Madagascar are poorer countries, which cannot afford expensive imports and, therefore, are often dependent on food aid to make up some of the deficit. In 1998, both food imports and aid were high for Comoros and Madagascar, due to an outbreak of brown locusts, which caused crop damage. The locust outbreak may have been linked to the El Niņo event, which caused hot, dry conditions (FAO/GIEWS 1998).