Grasslands of the World.pdf - Disasters and Conflicts - UNEP

Grassland perspectives 465
as well as vast tracts of semi -arid marginal land, are now under subsistence
crops . Tribal authority, which had regulated grazing practice, broke down in
many countries once they gained their independence, leaving grassland as an
open -access resource.
In North Africa , human population has increased greatly and traditional
authorities and grazing rights have broken down. Much semi -arid land has
been ploughed for unsustainable annual cropping. Livestock numbers have
risen and more can be carried through the lean season through the use of
purchased – at one time subsidized – cereals and concentrates. Transhumance
cycles are mostly greatly curtailed or herds have become sedentary. Uprooting
of shrubs for fuel causes severe damage. All the grazing land is overstocked and
degraded, often seriously so.
The situation in Patagonia contrasts sharply with that of East and South
Africa . In a little over a century from the introduction of sheep ranching, the
vegetation has been severely modified by overgrazing, mainly in the past fifty
years. Ranching is on private land with vast paddocks and little grazing control
within them. Guidelines for pasture management were only developed in the
1980s and have yet to make a strong impact.
The Campos is relatively well watered, and all stock rearing is commercial.
Pasture technology is well developed. Introduced forages are used to palliate
seasonal fluctuations in fodder availability and quality, either as sown pasture
or by over-seeding. The value of properly managed native pasture is increasingly
appreciated. Grasslands are generally in good condition .
The well drained parts of the Pampas are now farmland, where field crops
are often in rotation with sown pasture . The flooding pampa s is still exploited
as grazing land , producing stock for fattening elsewhere.
Many of the pastures of the Gran Chaco deteriorated seriously during
the twentieth century; before 1920 it had been almost unmanaged extensive
grazing . Provision of watering points allowed far more of the vegetation to be
consumed, leaving little to carry fire . This, together with uncontrolled felling
of forest led to invasion by undesirable thorny vegetation. Bush encroachment
brought about by overstocking and lack of grazing management is very serious,
leading to erosion, loss of wildlife habitat , and greatly reduced livestock
production. The economics of herbicides and mechanical clearing are not clear.
In most subtropical areas of extensive grazing, the strategic use of pasture resting
and controlled fire is the only economic way of keeping bush in check.
In the grasslands of Central North America the better-watered tall-grass
prairie is now mostly under crops . Vast areas of drier land have also been
cleared for cropping; much was marginal for crop production and suffers from
periodic drought , which led to the “dust bowl” of the 1930s. Much of the
marginal cropland has been reseeded or forested, with considerable government
support. Low returns from farming and the isolation of many rural communities
is resulting in urban drift. The modern trend is towards larger-scale