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

Grasslands of Patagonia 127
There are currently over 12 000 sheep farms (family or company owned)
in Patagonia , with flocks ranging from less than 1 000 to over 90 000 head
(Méndez Casariego, 2000). According to the latest on-farm population census
(1988) there were 75 000 people on sheep farms and irrigated valley farms. From
the 1970s to present, the rural population increased in Río Negro (+44%) and
Tierra del Fuego (+132%), remained fairly stable in Neuquén, and decreased
in Chubut (-33%) and Santa Cruz (-44%) (Méndez Casariego, 2000). Over the
same period, the on-farm population increased in Neuquén (+51%) and Río
Negro (+5%) and decreased in Chubut (-28%), Santa Cruz (-41%) and Tierra
del Fuego (-26%) (Méndez Casariego, 2000).
Patagonia ’s grasslands have only been grazed by sheep for just over a century.
Sheep numbers peaked in 1952, at over 21 million, and since then numbers
have been slowly shrinking, to about 8.5 million in 1999 (Méndez Casariego,
2000) (Figure 4.3). Ranchers raise unherded Merino (Plate 4.1) or Corriedale
flocks in continuously-grazed large pastures, usually for wool (Soriano, 1983).
Wool production is fairly insensitive to forage scarcity associated with high
stocking-rates or drought , so several authors have blamed present day land
degradation on the wool-oriented operations (Borrelli et al., 1997; Golluscio,
Deregibus and Paruelo, 1998; Covacevich, Concha and Carter, 2000). Cattle
have increased steadily over the last 50 years (Méndez Casariego, 2000) and
although present numbers (836 000) are more than double those of 1952, this
does not compensate for the decrease in sheep (Méndez Casariego, 2000).
The numbers of horses and goats have decreased considerably, but not as
dramatically as sheep. The most recent figures (1999) indicate that there are
180 000 horses and 827 000 goats – roughly half of the previous peak populations
(Méndez Casariego, 2000). Goat farming is mainly in the north, such as
Neuquén province, where numbers have remained fairly constant in spite of
the general negative tendency (Méndez Casariego, 2000).
Guanacos are the only large native ungulate (Soriano, 1983) and although
the region has generally been considered to have evolved under light grazing
pressure (Milchunas, Sala and Lauenroth, 1988), pre-European numbers of
guanacos may have been higher than previously thought (Lauenroth, 1998);
recent counts show populations are fairly stable at approximately 500 000
(Amaya et al., 2001). The native vertebrate fauna is poor (Soriano, 1983). The
lesser rhea (Pterocnemia pennata pennata) and the upland goose (Cloephaga
picta) are the most conspicuous birds . The Patagonian hare (Dolichotis patagonum)
and the small armadillo (Zaedyus pichyi), together with the lesser
rheas , are important zoogeographical indicators (Soriano, 1983). There are
significant numbers of predators , such as red foxes (Dusicyon culpaeus),
grey foxes (Ducisyon griseus), pumas (Felis concolor) and skunks (Conepatus
humboldtii) (Soriano, 1983). Red foxes and pumas are responsible for most
predation, and lamb losses due to red fox predation can be as high as 75 to
80 percent (Manero, 2001).