Effects of defoliation frequencies on above- and belowground biodiversity and ecosystem processes in subtropical grasslands of southern Brazil

Abstract

The links between vegetation and soil biota are responsible for a variety of ecosystem processes and services that can be affected by grazing. In this study, we aimed to evaluate the effects of grazing frequency in natural grasslands’ biodiversity (plant and collembola communities) and on ecosystem processes (decomposition and biomass accumulation). For so, we carried out a clipping experiment over a natural area of subtropical grassland in southern Brazil. The plots were submitted during three years to three different clipping frequencies (high, intermediate, and low) to simulate defoliation caused by grazing. We found the highest aboveground biomass accumulation and detritivore activity in the low defoliation frequency, which also promoted the dominance of tussocks. The synergies between higher vegetation height and biomass tend to provide microclimatic conditions that favors decomposition, which releases nutrients to plants, promoting their growth. The defoliation frequencies applied in this study were not sufficient to provide effects on plant community, since its co-evolutionary history with grazing. The Collembola community was not affected by defoliation. It seems to be more influenced by other factors associated with grazing.