CONICET | Buscador de Institutos y Recursos Humanos

Disturbanceslike biological invasions and fire may affect in unexpected ways plant-animalinteractions. In northwestern Patagonia, introduced ungulates (cattle, horsesand deers) are widespread and very common occupying more than 50% of forestsand shrublands, widely affecting these habitats. In addition, fire play a majorrole in creating landscape patterns in this region. We evaluated whether firemodify the impacts of introduced ungulates on plant-animal interactions. In amature forest (unburnt) and in an early post-fire area (burnt) we used structural equation modeling (SEM) to analyzed the impactsofintroduced ungulates on insect herbivory, pollination and pre-dispersal seedpredation on Berberis darwinii, oneof the most common understory shrub of temperate forests. We found that theeffects of cattle on pollination and fruit set depended on the habitat condition(i.e. unburnt or burnt). Introducedungulates in unburnt forest decreased fruit set through a reduction onpollinator visits. Conversely, introduced ungulates in burnt forest increased pollinatorvisits and flower production without affecting fruit set. On the other hand, damagepatterns (herbivory and fruit/seed predation) were unaffected by cattle in bothforests types. Either, low browsing preassure or induction of plant defencesmay explain our results.This study illustrates how modifications on biotic and abioticconditions produced by fire may affect in complex ways the effect of introducedungulates on plant-animal interactions.