EDAFOLOGÍA, VOL 13. (3), PP 161-169 2006
EFECTOS DEL PASTOREO EN CLIMA MEDITERRÁNEO ÁRIDO SOBRE PROPIEDADES FÍSICAS DEL SUELO
L. FERNÁNDEZ-POZO, T. BUYOLO y J. CABEZAS
Grupo de Investigación de Análisis de Recursos Ambientales. Facultad de
Ciencias. Uni- versidad de Extremadura. 06006. Badajoz. España.
The deterioration of a soil's physical properties leads to the breakdown of pedogenic pro- cesses and the consequent degradation of the soil. In an arid environment, this can end in desertification. We here describe, in the IV Region of Chile, the impact of grazing by comparing plots of land subjected to a grazing load of 25 goats ha-1 with plots excluded from grazing. Main climatic characteristics are: marked variability of rainfall (mean ca. 140 mm), maxima temperature of 28 °C in summer and minima of 6 °C in winter, and annual evapotranspiration in excess of 900 mm. Plant community consists of shrub (Flourensia thurifera, Gutierrezia resinosa, and Heliotropium stenophyllum) and grassland (Bromus berterianus, Plan- tago hipidula and Erodium cicutarium). The predominant soil is a Typic Camborthid. Grazed plots showed increased soil water content, available water-holding capacity, bulk density, microporosity, and penetration resistance, and decreased total porosity. In particular, the greater available water-holding capacity of the grazed plots corresponded to 22 % more water available for the vegetation, but the greater bulk density and penetration resistance and the lower total porosity were indicators of the soil's physical deterioration, with macroporosity being the most markedly affected, its reduction being by more than 60%.
Key words: Arid climate, Bulk density, Grazing, Penetration resistance, Porosity