Transformations of soil macroinvertebrate populations after native vegetation conversion to pasture cultivation (Brazilian Cerrado)

This study describes the impact on soil fauna populations after conversion of native vegetation to pastures. The invertebrate edaphic macrofauna was evaluated in areas where pastures are being introduced and renewed in the Cerrado, savannah biome. Five sites were considered in a Ferralsol area: a native vegetation area of Cerrado (CE), the deforested Cerrado (DC) and three areas involving pastures:9-years old pasture of Brachiaria brizantha (Pa9), a renewed pasture with the same plant (PaB), and a renewed pasture with Brachiaria associated with a legume, Stylosanthes guianensis (PaS). Thirty-six samples, at random, spaced 20 m apart, were removed from each site. A soil volume of 25 × 25 × 10 cm was delimited at each sampling point. The macrofauna was separated from the soil manually and then identified and weighed. The old pasture presents a higher biomass than the Cerrado area. Mechanical tilling, in both the old pasture and the Cerrado, caused a marked decrease in macrofauna populations. The renewed pastures PaB and PaS showed less diversity, population density and biomass than the deforested Cerrado. Termites were more abundant in the old pasture than in the other areas, however, the Cerrado (CE) showed greater diversity of termite genera and a greater number of predators (Araneae, Scorpions and Pseudoscorpions).