Abstract

FUNK, Flavia A et al. Recuperación estructural y funcional de los espacios entre arbustos al cabo de 10 años de exclusión del pastoreo en una estepa semiárida del noreste de la Patagonia. Ecol. austral [online]. 2012, vol.22, n.3, pp.195-202. ISSN 1667-782X.

Structural and functional recovery of intershrub spaces after 10-years of grazing exclusion in a semiarid steppe of northeastern Patagonia: In shrubby steppes of northeastern Patagonia, overgrazing of domestic livestock produces the formation of shrub islands distributed in a degraded matrix of bare soil or sparce vegetation cover. The structural and functional recovery of intershrub spaces through livestock removal would depend on the magnitude of degradation. If the system has crossed a critical threshold of degradation, the sole removal of the disturbance would be not sufficient to reverse the changes caused by grazing. The objective of this study was to assess the recovery of intershrub spaces in a site representative of the study system after 10 years of livestock grazing exclusion, by comparing soil coverage and soil physicochemical properties between ungrazed and grazed areas. Data sets were collected in four plots excluded from grazing and in areas adjacent to each plot that remained under continuous grazing. We measured the size of the intershrub spaces, and soil coverage (vegetation, erosion pavement, biological soil crusts, litter and bare soil), texture, nutrient content and infiltration rate. We found that the aerial coverage of perennial grasses and biological soil crusts was higher in ungrazed areas (27% and 45%, respectively) than in grazed areas (<1% and 3%, respectively). The size of the intershrub spaces was higher in grazed areas than in ungrazed areas. The physicochemical properties of soil and infiltration rate did not differ between ungrazed and grazed areas, except that bulk density and sand content in the soil-surface layers were slightly higher (7% and 3%, respectively) in grazed areas. The sole exclusion of grazing for a period of 10 years allowed the recovery of perennial grasses and biological crusts, suggesting that the structural and functional alterations of the intershrub spaces has not yet exceeded a critical threshold of degradation.

Keywords : Desertification; Rangeland degradation; Perennial grasses; Infiltration; Bulk density; Soil fertility.

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