TheImprovement ofTropical and Subtropical Rangelands

THE SOOIAL OONTEXT FOR RANGELAND IMPROVEMENT 41
rain received by two plots a few kilometers apart (Gilles and Jamtgaard,
1981). Nomadism serves to reduce environmental stress and
personal risk, but it is also more productive than settled livestock
husbandry. In eastern Mrica, in areas of Masai pastoralism, the
grazing capacity of the land is increased 50 percent because of herd
mobility (Western, 1982). In the important livestock-producing areas
of Mrica, comparisons of the productivity of mobile and sedentary
herds have indicated the superiority of mobility. In Sudan, Haaland
(1977) noted substantially higher mortality rates among sedentary
herds than among mobile ones. Breman and de Wit (1983) studied
the migratory system based in the Inland Delta of the Niger River in
Mali, and found that its productivity often exceeds that ofAustralian
and North American ranches.
Other studies in West Mrica have indicated that a disproportionate
number of sedentary cattle were lost in the 1968-1974 Sahelian
drought. Losses of herds that quickly moved into rainier regions in
response to the drought were minimal (Gallais, 1977; Sall, 1978).
Not only were the impacts of drought less severe on mobile herds,
but migrating herds caused less environmental degradation. Loss of
vegetation around boreholes where herds permanently congregated
was 10 severe that it could be easily recopized from satellite photos.
Mobility is an important aspect of production systems in semiarid
and marginal areas.
Mobility is just one way to cope with a harsh environment. Diversification
of subsistence activities is another. For farmers, the
ownership of livestock is one diversification strategy. Animals may
survive even when grain yields are quite low, so livestock may represent
a store of capital that can be used in years of drought. Farmers
may also grow a number of different crops to reduce the risk of crop
failure. Wheat and barley or maize and sorghum may be grown
together because one species tolerates drought better than another.
Diversification goes beyond the diversification of agricultural enterprises.
Farmers may also have secondary occupations, engage in
trade, or in migrant labor to reduce their dependency on a fickle
pastoral environment. In traditional subsistence-oriented societies,
this diversification lessened the dependence on the immediate environment
and lessened the probability of ecological disaster.
At first glance, traditional pastoralists would appear to have been
a highly specialized group dependent solely on livestock production,
but in reality these societies were highly diversified. First, multiple
species of animals were raised (figure 2-2). Camels, cattle, sheep,