Silvopasture and Carbon Sequestration with Special Reference to the Brazilian Savanna (Cerrado)

Abstract

The Brazilian savanna, known as the Cerrado, extending over 200 million ha, is the largest neotropical savanna in the Americas. With its ongoing conversion to intensive agriculture since the 1960s, of which cultivated pastures for beef cattle production is a major form, this unique ecosystem is now considered threatened. Given the recognized role of trees in carbon (C) sequestration and greenhouse gas (GHG) mitigation, the silvopastoral system of tree plantation development on pasture lands is considered to be particularly relevant to this region. For the past two decades, eucalyptus-based silvopastoral systems have been established in the Cerrado region by growing agricultural crops (rice and soybean) in the first 2 years followed by Brachiaria forage and beef-cattle grazing from the third year of plantation establishment. Recent studies in a variety of situations indicate that agroforestry systems store higher amounts of C compared to single species cropping and grazing systems, both aboveground and belowground. The Brazilian savannas that have characteristically low aboveground C reserves hold considerable stocks of soil organic C, probably as a consequence of previous land use, the history of which is unknown. Most of this C is in a biodegradable form and is likely to be lost to the atmosphere when the soil is disturbed during land conversion to agriculture and pasture. Adoption of sustainable land use systems such as silvopasture could reduce this potential hazard. Given the role of the Cerrado in the global C cycle and climatic change, these issues deserve well coordinated investigations.