Viabilidade econômica e ecológica dos modelos sucessionais de restauração florestal nos serviços ambientais na Mata Atlântica brasileira

Abstract

Restoration of tropical forests with the aim of sequestering carbon is one of the current needs in the fight against climate change. However, it presents a high cost of restoration projects. The combination of native species with eucalyptus cultivation can generate carbon credits and economic return with the exploitation of eucalyptus wood, amortizing restoration costs. This study aims to evaluate carbon stocks in different successional models with eucalyptus (Eucalyptus urophylla) intercropping in the Atlantic Forest of Sergipe. It also evaluated wood production in treatments that have intercropping with eucalyptus plantations. Three treatments were evaluated: T1- restoration using the active model, without eucalyptus; T2- restoration by the active model, with eucalyptus and T3- restoration by the passive model, with eucalyptus. A reference forest was also evaluated. Sixteen plots measuring 25 x 25 m (four for each treatment) were installed in a completely randomized design, with tree individuals measured from 15 cm of CAP, in addition to measuring the total height with a telescopic pole and botanical identification. To estimate the carbon stock from the biomass data, a 47% carbon content was used for all plant compartments. Herbs and litter were sampled using a 1x1 m template in the center of each plot. Soil was collected at depths of 0-5, 5-10 and 10-20 cm to measure the carbon content and included the use of a volumetric ring for density determination. All samples were sent for analysis with subsequent determination of carbon content in the soil laboratory at UFS. At the end, the carbon contents of the stocks were determined (in Mg ha-1 ). Stocks were valued at the social cost of carbon (in US$) and differences between income and expenditure (both in US$) were compared with stock values at 9 years of age. The forest formed by the active model with E. urophylla showed the best total carbon stock result between restorations (62.06 Mg C ha-1) equaling the secondary forest stock (64.68 Mg C ha-1). The carbon stocks of the consortium models amortize 43.41% (ative) and 126.02% (passive) of the restoration costs, with the largest discount applied to the passive model, considering the environmental services of carbon and E. urophylla wood. Despite this, the non-consortium active model, with a lower carbon stock (33.84 Mg C ha-1) is the one that presents economic (23.67%) and ecological viability (H'=2.46, J=0, 78), as the forest formed at age nine is at a more advanced succession stage than that of the other tested models. Studies point to the importance of considering the use of species adapted to local peculiarities and silvicultural practices in active and passive models, especially when looking to amortize restoration costs with a focus on carbon and Payment of Environmental Services (PES).