1. Biology Department, Federal University of Lavras (UFLA), Lavras, Minas Gerais, Brazil
2. Soil Science Department, UFLA, Lavras, Minas Gerais, Brazil
3. Soil Department, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
4. Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium