Os sistemas agroflorestais na provisão de serviços ecossistêmicos e na transição agroecológica na Pan-Amazônia

Abstract

Agroforestry Systems (SAFs) have the potential to provide a wide range of ecosystem services for human well-being. However, developed agroforestry initiatives deserve greater attention and visibility to foster public policies for forest restoration and protection. The objectives of this study were: 1) to evaluate the effect of vegetation richness and structure on carbon stocks in different agroforestry systems; 2) evaluate carbon stocks and carbon recovery in a chronosequence of agroforestry systems and secondary forests and 3) to identify social, economic or environmental factors that encourage farmers to adopt diversification practices in agriculture. For Objective 1, 25 SAFs and 4 secondary forests were sampled in the southern Amazon of Bolivia. In each area a circular plot of 1963 m2 was installed, where the richness of the vegetation and the carbon stocks aboveground were evaluated. For Objective 2, 31 SAFs and 36 secondary forests were sampled and grouped in three successional categories (young, intermediate and mature) in the eastern Amazon of Brazil, as well as 13 mature forests 8 conserved. In each area a circular parcel of 1963 m2 was installed, where the carbon stocks above and belowground were evaluated. For Objective 3, agroforestry experiments were developed to increase diversity (biological and productive) and the provision of ecosystem services in degraded areas, and factors that encouraged farmers to adopt diversification practices in agriculture were assessed through participatory processes and semi-structured interviews. The richness of species and variation in vegetation structure, contribute to the increase in carbon stocks in above-ground biomass in agroforestry systems. Richness as a pure factor contributed 12.7%, structure 8.8% and structure variation 4.8%. Total carbon stocks in SAFs and advanced secondary forests were 89.29 and 70.62 Mg ha-1, respectively. The recovery of carbon at 30 years in relation to mature forest reached 38% in SAFs and 27% in secondary forests. Our results suggest that SAFs and secondary forests are important as carbon sinks and that species richness and stratification of the system influence the potential for ecosystem service provision. Formal education is not related to the adoption of biodiversity systems or the promotion of environmental protection actions. However, farmers in agroecological transition have ensured increased resilience through increased crop species diversity and soil management. Facilitating participatory processes of dialogue and exchange of experiences is essential for the agroecological transition.