Use of food availability by guanacos (Lama guanicoe) and livestock in Northern Patagonia (Mendoza, Argentina)

PUIG, S.; VIDELA, F.; CONA, M.I.; MONGE, S.A.

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2001 vol. 47 p. 291 - 308

0140-1963

Grazing areas of a guanaco population were shared with introduced livestock in a protected area of Northern Patagonia. Ungulates diets and food availabilities were compared to recognise interspecific overlaps and to detect potential plant depletions. Seasonal faecal samples were analysed by microhistology, and food availability by point-quadrat transects, in sandy and rocky habitats. Large ungulates were classified as “strictly grazers”, while small ungulates as “grazers-browsers”. Food limitations constrained ungulates feeding tendencies, in agreement with the selective quality hypothesis. A shared use with preference of scarce items, as most forbs and four grasses, advise about their risk of disappearance by overgrazing. Main dietary items annually shared were the grass Poa and the camephyte Hyalis, whose conservation would be essential for the guanaco population. Despite its high dietary diversity, guanacos could be affected especially by shared food use with sheep and horses in sandy habitats. Cattle would be the most affected by shared use with horses, sheep or goats. Fires and woody plant extractions caused a decrease of shrubby stratum, food diversity and patchiness, and could force an increase of competitive risks. Management priorities are to monitor the plant cover and diversity, discourage a livestock carrying increase, avoid the shrubs extraction, and control the fires generation.