Domestic cattle as drvers of andean subtropical rainforest (Yungas) dynamics

MAZZINI FLAVIA; RELVA MA ANDREA; MALIZIA LUCIO

Évora

Congreso; World congress Silvo-Pastoral Systems; 2016

Large mammalian herbivores play important roles as drivers of communities and ecosystems. The impacts of herbivory on vegetation have been widely studied on grasslands, while herbivory impacts on woody communities remain less explored. Cattle have been suggested as one of the main causes of forest degradation and biodiversity impoverishment in neotropical montane forests (Yungas). Since the understanding of cattle impact on this plant community is scarce and mostly based on anecdotal data, quantifying cattle use and damage is crucial in order to promote forest conservation and a proper management. In Argentinean Yungas we studied the impact of cattle use on the abundance and size of regeneration of the main forestry species, and on the structure and floristic composition of understory under a variety of different browsing regimes. Twenty-five stands were sampled, recording site variables, vegetation attributes and animal relative abundance in Jujuy and Salta provinces during 2014 and 2015. Principal Component analysis (PCA) indicates that abundance and richness of tree seedling species are negatively correlated with cattle abundance and browsing intensity. Understory abundance is positively correlated with the stand structure and negatively with cattle abundance. It should be taken in consideration that extensive ranching is an ancient activity in the study site, thus present species survived the grazing and browsing pressure of cattle. It is necessary to add more sites and found some place with little or no ranching activity at all or at least in the past 100 years. Due to the importance in terms of biodiversity, wood provisioning and ecosystem services, Yungas management and conservation is a high priority for Argentina.