Runoff And Sediment Yield From Forested Catchments Under Varying Management Intensities: Insights From A Subtropical Region Of Brazil

Streams have tolerance limits to certain environmental conditions, high levels of sediment can influence water quality and, consequently, aquatic life and human health. Considerable research in temperate forest ecosystems has elucidated the dynamics of suspended sediment export and the role of forest management on changing sediment yields, but fewer studies for subtropical regions exist. The objective of this study was to evaluate the effects of forest management on suspended sediment export under varying forest cover and management conditions in subtropical Brazil. Three catchments, with different management systems, were evaluated: eucalyptus forest plantation with even-age stands management (EUC), native forest (NAT), and mosaic of forests plantation with different species and ages (MOS), located in southeastern Brazil. Streamflow, precipitation and turbidity data were collected by pressure transducers, automatic rain gauge and YSI 6136 turbidity sensors, respectively, during the period from November 2016 to October 2017. The suspended sediment yield was estimated through a relationship between turbidity and suspended sediment concentration. The results showed that sediment export ranged from 0.032 Mg ha(-1)yr(-1)to 0.411 Mg ha(-1)yr(-1). The catchments studied presented a low sediment export rate, compared to other studies conducted in forested settings worldwide. Our results provide insights into the high-frequency sediment production dynamics of Brazilian forested catchments and demonstrate that, regardless of the forest management system applied in the area, native or exotic planted forests are capable of protecting the soil and minimizing the effects of sediments export.