Impacts of domestic cattle on forest and woody ecosystems in southern South America

摘要

There is a long lasting debate on the effects of domestic cattle grazing on natural ecosystems worldwide. Cattle are generally assumed to have negative effects on forest conservation; however, several studies also report positive and neutral effects. We aimed to investigate the available evidence for positive, negative and neutral effects of cattle grazing on forest and woody ecosystems of southern South America. We conducted a peer-review literature search using the ISI Web of Knowledge and Scopus databases to identify studies dealing with cattle impacts for nature conservation. We compiled a database of 211 cases from 126 original publications. A reduced number of forest ecosystems (Patagonian forest, Chaco and Monte) concentrated similar to 85% of the reported study cases. The hierarchical cluster analysis to group cases based on cattle effects, ecological variables and ecosystems reported that negative effects (similar to 66% of cases) were mostly informed for vegetation variables and mainly occur in Patagonian forest and Chaco; positive effects (similar to 16%) were mostly informed for Monte (no particular variable associated), while neutral effects (similar to 18%) were mostly informed for fauna-related variables and Uruguayan savanna. Our study suggests that grazing effects by cattle on southern South America forests are not homogeneous and depend on the particular forest ecosystem considered as well as on the forest attribute measured. Different cattle effects found can be partially explained by differences in grazing history and different ecosystems productivity. It is vital to improve our understanding of cattle-forest interactions to guide synergies between sustainable management and forest conservation.