Benefícios ambientais e econômicos de sistemas agroflorestais de Tomé-Açu, Pará

Abstract

The global demand for food and the advance of climate change generate pressure for sustainable production systems that generate multiple benefits. Agroforestry systems (AFS) are productive models with the potential to meet the demands of society and the environment. In this sense, this research aimed to evaluate agroforestry systems' contribution to climate change mitigation, biodiversity conservation, and income generation in the municipality of Tomé-Açu, Pará. Twelve areas of multi-stratified AFS were selected and a 30 x 30-meter plot was installed in each system. An agroforestry inventory and an interview with the producer about the socioeconomic profile and environmental perception of the AFSs were carried out. The data were used to evaluate the influence of plant richness and other variables on the benefits of "Mitigation of climate change", "Biodiversity conservation" and "Income generation", through the indicators aboveground biomass carbon stock, Shannon index (H') and gross income, respectively. For this, we used Principal Component Analysis (PCA) to select the variables and linear regression to create the models. All data from the agroforestry inventory and the statistical analyses were performed in the R 4.2.2 computing environment. In general, 83% of the farmers reported being satisfied or very satisfied with the economic return on the AFSs, in addition to citing several environmental services. Richness (S) per system ranged from 3 to 11 species and Shannon diversity index (H') between 0.55 and 1.77. The average carbon stock of the aboveground biomass in the studied AFSs was 45.2 Mg ha-1, with a variation between 27.4 and 63.0 Mg ha-1. The values of carbon stock in the cocoa, cupuaçu, açaí, dendê, and other components were statistically similar, but differed significantly from the carbon stock found in the forest component (gl=2; χ2=71.7; p=1.834e-13). The average value of annual gross income from the sale of these producers was R$13,758, 53/ha and ranged between R$1,687.50 and R$26,250/ha. In the systems with oil palm (AFSs A1, A2 and A3), the palm tree considerably increased the gross income of the AFSs, contributing 58, 48 and 78% of the total income, respectively, despite the low density of individuals, with an average of 69 ind ha-1, in the areas, in comparison with the other main species. In this study, it was not possible to confirm the influence of plant richness on the generation of climate benefits, biodiversity conservation, and income generation. However, other variables influenced the benefits of the analyzed AFSs. "SAF type", "oil palm density" and "shade species density" performed best on carbon stock, Shannon diversity index and gross income, respectively. As for the benefit scores, in general, most of the AFSs showed unevenly distributed scores for each benefit. Therefore, we conclude that plant richness was not the variable that influenced the benefits evaluated, but rather a set of variables analyzed, ratifying the complexity of Tomé-Açu's AFSs. In general, the AFSs of Tomé-Açu meet the expectations of producers in terms of economic return, besides generating benefits related to climate change mitigation and biodiversity conservation. In particular, the AFSs with the oil palm component showed better performance in the scores of benefits generation.