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

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Grasslands of the world
Figure 3.10
Rangeland production in South Africa using the model of Le Houérou, Bingham
and Skerbek (1988) and median annual rainfall (Dent, Lynch and Schulze, 1987).
likely to lead to system run-down. In the communal areas of the Eastern Cape,
livestock numbers at the district level reflect the fact that stocking rates are
substantially higher than those applied by freehold graziers and recommended
by the Department of Agriculture. This presents a problem for administrators,
who are unable to reduce livestock numbers in areas where graziers are unresponsive
to regulation.
Production relationships can be simplified to straightforward expressions of
kilograms of annual dry matter production of forage per millimetre of annual
rainfall (Le Houérou, 1984). An aboveground biomass production model
based on the concept of rain-use-efficiency has been developed (Palmer, 1998)
and applied to rangeland. The resultant map for commercial production is
shown as Figure 3.10. Production may be converted to carrying capacity for
cattle by assuming a daily requirement of 11.25 kg DM/LSU and a use factor
of 0.4 (Le Houérou, pers. comm.). The use factor may decline to 0.2 in mesic,
“sour ” grasslands with high C:N ratios.
The second focus of research to receive substantial government funding in
support of intervention policies was assessment of grazing systems . During
1950–1990 it was expedient for government to provide support for fencing ,
water points and stock management infrastructure. Field trials were designed to
assess the advantages of rotational versus continuous grazing . Rotational grazing
requires that the pasture allocated to a group or groups of animals be subdivided
into one enclosure more than the number of groups (Booysen, 1967).
According to Tainton, Aucamp and Danckwerts (1999), the primary objectives
of rotational grazing are to: