Accumulation of carbon and age of thinning of the tree component in agroforestry systems

Abstract

Agroforestry systems (AFS) are considered large sinks of greenhouse gases (GHG) in the atmosphere. However, little is known about the dynamics of carbon accumulation in tree individuals over the years and the Age Thinning Technique (ATT) to potentialize GHG mitigation. The objective of the study was to predict the growth in carbon and determine the age thinning Technique of the tree component in 3 AFS in the municipality of Viçosa, MG, Brazil, in which System A is composed of eucalypt (Eucalyptus saligna) + pasture (Brachiaria decumbens) and systems B and C with eucalypt (Eucalyptus urophylla x Eucalyptus grandis) + pasture (Brachiaria decumbens). The Gompertz and Logistic models were employed to predict the timber volume and carbon growth. The ATT was determined based on the maximum productivity in timber volume per unit area. The curve asymptotic values of the systems A, B and C were 450, 221 and 226 m3 ha-1 for the volume and 104, 51 and 52 MgC ha-1 for the carbon, respectively. Stabilization of carbon accumulation will occur close to 100 months for systems A and B and at 80 months for system C. As the ATT ranged 64-80 months, the thinning is recommended before this age to promote the carbon accumulation of the remaining arboreal individuals.