Cattle effects on the resource allocation in woody species of Andean Patagonian shrublands and forests.

Resumo

Cattle effects on the resource allocation in woody species of Andean Patagonian shrublands and forests. Herbivores, and large mammals in particular, are capable of modifying not only the architecture of the species they graze on, but also growth rate, productivity and the way the plant uses its resources. This study analyze how cattle influence changes in resource allocation (to aerial biomass or root and/or reproductive or vegetative biomass) in two dominant species with different palatability, in a post-fire Nothofagus pumilio forest. The relationship between possible changes in resource allocation and the variables which indicate successful reproduction in these species (e.g., number of flowers and fruits) was also determined. The presence of cattle negatively affected the total biomass of the palatable species (R. magellanicum) and modified the proportions assigned to its shoot/root and vegetative/productive biomass. In contrast, the allocation of B. microphylla resources was unaffected by the cattle presence, but its highest reproductive success was associated with plants of larger size that occur in cattle plots. These results show that the cattle have different effects on the species: directly, through removal of biomass (on palatable species), and it’s possible also indirectly, through changes in the availability of light (on non palatable species).