Impactos da conversão de campo nativo em monocultura de soja na fauna de colêmbolos epiedáficos do pampa brasileiro

Abstract

The edaphic fauna is a fundamental part of the soil ecosystem’s dynamics. Among the components of the edaphic fauna can be highlighted the Collembola, small arthropods that present great sensitivity to physical-chemical changes in the environment where they are inserted. Changes in the Collembola fauna may indicate changes caused by anthropic disturbances, such as the conversion of native grasslands for use in plantations. The Pampa biome is a highly diverse grassland environment, poorly protected, and sensitive to environmental changes. Thus, in this study, ecological indices of Collembola populations were used to identify the possible alterations of the conversion of native grasslands in the Pampa biome into soybean plantations. The Collembola fauna was compared in nine paired grassland and soybean sites in four municipalities in the Brazilian state of Rio Grande do Sul. The effects of conversion, and environmental factors involving soil, vegetation, climate and geomorphology were taken into account. A total of 975 specimens were counted: 359 in native field areas and 616 in soybean areas. The analyses indicated significant changes in species composition between communities. Although abundance was higher in soybean areas, the Shannon Diversity Index was higher in native grassland areas. No significant differences were found in the richness and Pielou Equitability Index between the areas with different land uses. Regarding environmental variables, the Shannon Diversity Index was positively affected by the variables: elevation, plant richness, plant diversity and richness of nongrass plants. The increase in the population of Collembola may indicate upwelling in the plantation areas after the disturbance, as well as potential simplification in the trophic chains. The reduction in the number of predators, the changes in the physicochemical characteristics could explain this phenomenon.