Influence of Goat Densities on Vegetation, Hydrology and Soil Properties in a Chihuahuan Desert Range

Abstract

An IS-month study was conducted on a Chihuahuan desert range in
northeast Mexico to determine the effect of two intensities of crossbred Criollo
goats grazing (1.5 or 15 ha per' goat) on vegetation, hydrology and soil properties.
The greatest change in vegetation on the heavily grazed pasture was the decreased
cover of shrubs (15% units for Larrea tridentata), compared with the lightly grazed
pasture (P<0.05). Light goat grazing promoted total perennial grass cover compared
with heavy grazing (2.3 vs. 1.3%, on the average). Forbs were not affected by.
stocking rate over several seasons. Persistent high goat browsing affected neither
water infiltration rate nor soil losses. Stocking level had no effect Ion soil pH,
organic matter, mineralizable nitrogen and total nitrogen content, but near the settlements,
the heavily grazed pasture contained 77% more (P<0.05) phosphorus and 163%
more (P<0.05) copper in the top 0-30 cm soil layer than the lightly grazed pasture.
Potassium was 15% higher (P<0.05) in the lightly grazed pasture than the heavily
grazed site as goats browse principally around the areas close to the settlements.
It was concluded that high chronic levels of goat hervibory altered the rangeland,
changing it to an ecosystem with a reduced shrub cover, without affecting water
infiltration and soil losses.