Impacts of reforestation on soil and soil organic carbon losses

Abstract

Water erosion is a serious environmental problem that causes soil degradation, compromises its fertility and causes soil organic carbon (SOC) losses. Reforestation, encouraged by Brazilian environmental legislation, is a way to reduce water erosion. However, in tropical and subtropical regions, there is little information on the impact of reforestation on soil loss rates and SOC. Therefore, this study aimed to apply the Erosion Potential Method, combined with multitemporal data from soil samples collected in situ, to estimate and spatialize soil and SOC losses in a predominantly agricultural Brazilian watershed that showed high rates of reforestation in the period studied from 2011 to 2019. The determination of the EPM parameters was carried out with the aid of a Geographic Information System and the soil loss estimate was validated with information from a hydrosedimentological collection station. The results showed that between 2011 and 2019 water erosion was reduced by 27.5%, while carbon losses were reduced by 32.7%. Among the evaluated crops, corn showed the highest soil and SOC losses, while coffee and forest areas exhibited the lowest rates. Reforestation of the basin is the main factor responsible for the reduction of soil losses. This process was initiated seeking to meet the requirements of the Brazilian Forest Code, which highlights the positive role that public policies can play in environmental conservation when respected and well applied.