ROBERT F. BARNES
USDA/Agricultural Research Service, P.O. Box 19227, New Orleans, LA, U.S.A., 70179-0227
Savanna ecosystems occur throughout the worlds tropics and subtropics and cover approximately, a quarter of the earth's surface. They, are characterized by, a set of conditions involving seasonal wet and dry, climates and more or less continuous ground cover of predominantly C4 grasses within a continuum varying from grassland through low tree and shrub communities to woodland. They, are primarily, used for grazing and ruminant livestock production.
Constraints differ among the various ecosystems, but the key, problems encountered in most savanna ecosystems include: extensive cattle production associated with Iow pasture productivity, and quality due to seasonal dry, periods and periodic droughts; low soil fertility including acid soils with mineral deficiencies and/or excesses in many, areas; lack of legume persistence; and pests and diseases of pasture plants.
The savannas of the world contain a large and growing proportion of the worlds population and are thus being subjected to increasing pressures. To support these increases in population, land use must become more efficient. This can only, be done by addressing the total socio-cultural and economic incentive framework of that population.
As changes are contemplated, taking into consideration the interests of the people affected is fundamental for success.
The challenge for more intensive use of savanna ecosystems for grazing livestock is to not only conserve resources but to utilise them more efficiently and effectively; to even the balance between the under-use of wet-season and over-use of dry-season grazing areas; and to improve the overall quality of feed available. It requires a high degree of management expertise with a deep understanding of the land and water resources as well as the plant and animal resources.