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

A.F. CIBILS
Chapter 4
Grasslands of Patagonia
Andrés F. Cibils and Pablo R. Borrelli
SUMMARY
Patagonia lies between 39° and 55°S, partly in Chile but mainly in Argentina ;
its extra-Andean portion is treeless semi -arid grass and shrub steppes that have
been grazed by domestic livestock for a little over a century. The climate is arid
to semi-arid, and cool to cold , with mean temperatures decreasing from 15.9°C in
the north to 5.4°C in the south. Extra-Andean Patagonia is an area of semi-arid
grass and shrub steppes; vegetation is characterized by xerophytes. Guanacos are
the only large native ungulate herbivore and the region has evolved under light
grazing pressure . Most vegetation has been seriously modified by sheep , particularly
in the past 40–50 years, with palatable grasses being replaced by unpalatable
woody plants. Private property is the main land tenure form. Human habitation
probably began about 10 000 years BP, but European settlement began at the end
of the nineteenth century, with commercial sheep farming. Aboriginal peoples
were hunter-gatherers; private property limited their opportunity for migratory
hunting. The success of early settlers encouraged more immigrants, who occupied
progressively drier areas, until 1940. Sheep numbers peaked in 1952, at over
21 million head, and have since fallen to 8.5 million head. Cattle , kept at higher
elevations near the Andes, are the next largest stock; herds have increased over the
past 50 years. Horses and goats have decreased less dramatically than sheep. Sheep
121