Soil Organic Carbon as Response to Reforestation Age and Land Use Changes: A Qualitative Approach to Ecosystem Services

Abstract

The proper management of soil, in order to improve ecosystem services, requires knowledge of how different fractions of carbon respond to land use/land cover changes. This study aimed to evaluate the responses of total soil organic carbon, and its fractions, to reforestation age and land use changes in an Ultisol in the Posses catchment, a pilot area of the Brazilian program of Payment for Environmental Services, located in Southeastern Brazil. The study was conducted using field plots with various treatments, including native forest, old and young reforestation, well-managed pasture, subsistence farming, degraded pasture, and bare soil. Results showed that soil organic carbon increased with reforestation age and that original soil carbon stocks were restored after eight years of reforestation. Short-time pasture management increased the carbon pool by 10% compared to degraded pasture. The Carbon Management Index (CMI) was able to distinguish the effects of converting degraded pasture to either subsistence farming or bare soil. The CMI is a useful tool for determining the effects of land use/land cover changes, reforestation age, and native forest preservation on soil quality. Adequate management of soil fertilization is an immediate option for restoring the quality of Ultisols under degraded pastures in the Posses sub-basin.