Desertification means a process of degradation of the environment that usually is a product of climate and human activity and involves the spread or extension of desert-like conditions in a hitherto fertile area.
Most of the vegetation in arid and semi-arid regions is threatened with man-made desertification, a result of excessive, indiscriminate, and archaic land-use practices. Forest grazing is the most serious cause of desertification in arid and semi-arid areas, and shifting cultivation is likewise important in the humid tropics and N.E. Himalayas. Increasing population pressure has greatly accentuated the adverse impacts of the above causes.
Desertification used to be an issue of considerable concern during the 1970s and 1980s, but not much credence is now given to the theory of deserts advancing and swallowing up adjacent savanna landscapes (Warren and Agnew, 1988; Nelson, 1988). According to UNEP (1984), in 1983 it was estimated that 17 per cent of the world’s arid, semi-arid and sub-humid regions had suffered some loss of productivity.
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More recent studies have questioned the methodology used to derive the statistics used to quantify the rate of desert expansion (Young and Solbrig, 1992). Though land degradation resulting from removal of the vegetation cover is a serious problem throughout the world’s savannas, reliable statistics on the extent of land degradation are lacking.
Loss of biodiversity is also a serious problem in savannas but here also its extent is not known. In areas of high domestic grazing pressure, loss of animal biodiversity is aggravated by a reduction in the number of forage plants available for wildlife.
The goat is the most serious agent of forest grazing. Many examples of goats being the main cause of desertification are known. The goat has been aptly called “the razor of forests” (Maydell, 1980). In the tropics and subtropics, the stock of goats is estimated to exceed 300 million.
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Destruction primarily affects the shrub and tree vegetation where goats prevent regeneration and damage established plants. When the vegetation cover is destroyed, it leads to soil erosion and irreversible destruction of ecosystem.
The intensity of grazing damage depends primarily on the following factors:
1. The composition of the herds (cattle, goats, sheep);
2. The duration and frequency of grazing on the same area, and also the seasonal grazing pattern;
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3. The type of forest and its soil, and its management practices, etc.;
4. Ways of using the forage reserve of the forest.
Goats are particularly destructive to trees and shrubs because they eat virtually all parts of forest plants including young shoots, twigs, fruits and bark. In the thickly vegetated moist forests, goat grazing does not cause serious damage, but in the arid zones where vegetation is already sparse, the goats become a serious menace. In these situations, the goat becomes the arch-enemy of forests.
One solution to reconciling the conflicting interests of forestry and goat husbandry is a clear separation of forestry and pastoral land-use practices. This can be done by fencing.
Another approach is to replace the archaic, destructive ways of forest grazing by controlled utilization from which both forestry and pastoralism derive mutual benefit.
Some promising methods to achieve this goal include:
(1) Partial substitution of goats by other, less destructive animals, e.g., sheep;
(2) Reduction in the number of animals per unit area;
(3) appropriate rotational practices, i.e., plantations for fuel wood, timber, etc., and
(4) introduction of controlled grazing in forests.
A third approach involves forage production as a forest management goal. That is, forage species are grown on areas allotted to forestry. Shelter belts, shade trees and other trees which check erosion can be gainfully planted. The grass, fruits and litter in the forest are utilized as fodder for goats. Natural forests enriched by fodder plants can be established.