The effects of cattle grazing in savanna ground layer invaded by exotic grasses

Abstract

One of the most significant issues regarding open ecosystem conservation is the broad occurrence of invasive plant species. Invasive grasses, in particular, produce volumes of biomass far higher than native grasses, outcompeting the native vegetation and altering fire regimes and fire behavior. Cattle grazing has been suggested as a potential solution to control the invasive species. However, empirical studies are needed to provide evidence-based recommendations and assess possible damages to the native species. Aiming to fill this gap, we implemented an experiment to evaluate the effects of cattle grazing on plant community structure and composition in the Cerrado (Brazilian savanna). Specifically, we are going to test (i) if cattle grazing changes the relative abundance of native and invasive species and (ii) if the native species' response to grazing is mediated by functional traits. The experiment was implemented in an open savanna partially invaded by exotic grasses. A BACI approach (before-after-control-impact) was used to compare changes over time with and without cattle, considering structure, floristic and functional composition. To shed light on the functional diversity of the ground layer with and without the disturbance by cattle, we will explore which plant traits (related to growth form, plant architecture, palatability, resprouter type and underground structure) are linked to species persistence, expansion or decrease. By addressing these issues, our study will contribute to the validation of nature-based solutions for Cerrado conservation in invaded scenarios. The challenge, in this case, is finding a way to keep the Cerrado plant diversity despite the invasive grasses, since eradicating them has proven to be an unfeasible solution.