TheImprovement ofTropical and Subtropical Rangelands

Overview: Dimensions ofa Worldwide
Environmental Crisis
TID GEOGJlAPBICAL SCOPE
Rangelands are one of the DlOBt important land U8e typ_ in the
world. Roughly 47 percent of the earth'. land lUlface is r8llpland,
about 80 percent of which is at leut moderately desraded. Subetantially
more th8ll halfofthis areali.in tropical8lld subtropical areu.
By contrast, 1.. than 10 percent of the earth'. lUlface is devoted to
arable agriculture. In recent yean, desradation hu been increuing,
and many of the world'. maJor r8llgelands are at risk. The d_rtification
huards map, compiled by several United Nations apncies,
mOWll areas that are at greatelt risk of desertification bec&WJe of a
continuation of facton such u low rainfall, terrain, lOil and vegetation
conditions, and high human 8Ild animal U8e. Identifying way. to
arrest and reverse th_ trendl is the central concern of thilltudy.
Tropical 8Ild subtropical rangel8lld is Ulually characterised by
rainfall 80 low or irregular that crop production is difBcult unl..
irrigation sylltem8, which require high capital inveltment, can be
establilhed. Typical vegetation types include sr_8Ilds, low-deDlity
forests (such u dry tropical thorn foresta), 8Ild shrubl8lldl. The term
desert is commonly applied to thOle r8llplands that are the mOlt
arid and leut productive of vegetation.
Rangelands are UIed to .upport gruing of browsing livestock.
The open-range system of livestock production is characteristically
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