Effects of tradicional grazing and livestock exclusion on soil properties in fragmented mountain woodlands of Central Argentina

RENISON, D., HENSEN, I., CINGOLANI, A. M., MARCORA, P. & GIORGIS, M. A.

AUSTRAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2010 p. 435 - 443

1442-9985

Mountain forests and their soils provide ecological services such as maintenance of biodiversity,provision of clean water, carbon capture and forage for livestock rearing, which is one of the principal economicactivities in mountain areas. However, surprisingly little is known about livestock impact in South Americanmountain forest soils. With the aim of understanding how livestock and topography influence patterns of forestcover, soil compaction, soil loss and soil chemical properties, we analysed these parameters in 100 Polylepis australiswoodland plots situated in the humid subtropical mountains of Central Argentina. We used distance from thenearest ranch as an objective index of historical livestock impact and measured standard topographic variables. Ourmain results reveal that distance from ranch in all cases partly explains tree canopy cover, soil loss, soil compactionand soil chemical properties; suggesting a strong negative effect of livestock. Intermediate altitudes had more treecanopy cover, while landscape roughness – a measure of the variability in slope inclination and aspect – wasnegatively associated to soil impedance and acidity, and positively associated to soil organic matter content. Finally,flatter areas were more acid.We conclude that livestock has had a substantial influence on forest soil degradationin the Mountains of Central Argentina and possibly other similar South American mountains. Soil degradationshould be incorporated into decision making when considering long-term forest sustainability, or when taking intoaccount retaining livestock for biodiversity conservation reasons. Where soil loss and degradation are ongoing, werecommend drastic reductions in livestock density.