Agroflorestas e ação climática no semiárido piauiense: sequestro de carbono, convivência com a seca e monitoramento produtivo da terra

Abstract

The research evaluated the potential of agroforestry systems (AFSs) as production systems adaptable to the conditions of the Piauí semiarid region, considering their contribution to soil carbon storage, chemical quality conservation, microclimate amelioration, and adaptation to drought conditions. The study was conducted across four agroforestry systems AFSs 16, Sabiá, and 22, located in the municipality of São Lourenço do Piauí, and AFS Belém, in the municipality of São João da Serra using native forest areas as spatial references. The research adopted an exploratory and integrated approach, involving a literature and document review, field observations, laboratory analyses, and the assessment of microclimatic variables. Soil samples were collected during both the rainy and dry seasons at depths of 0–10 cm and 10–20 cm to determine total organic carbon and chemical attributes related to soil fertility. The investigation also assessed temperature, relative humidity, and the ultraviolet index, while employing descriptive statistics, Pearson correlation, principal component analysis, and hierarchical clustering to interpret the relationships between the systems and the analyzed variables. The results demonstrated differences among the AFSs regarding chemical attributes and total organic carbon levels; notably, AFS 16 exhibited the highest mean total organic carbon (14.232 g/kg)—a value 52% higher than that recorded in its native forest reference area—while AFS Belém showed 7.770 g/kg, representing a 90.9% higher value compared to its reference. Organic carbon showed strong positive correlations with cation exchange capacity (r=0.90), calcium (r=0.89), the sum of bases (r=0.88), and base saturation (r=0.71), indicating an association between carbon storage and attributes related to soil chemical quality. Multivariate analysis revealed differences in the chemical organization of the systems, associating SAF 16 with fertility attributes and indicating distinct trajectories among the other SAFs based on environmental conditions and management strategies. Microclimatic results indicated that the Sabiá and Belém SAFs exhibited milder temperatures and higher relative humidity compared to their reference areas, whereas SAF Sabiá exhibited an ultraviolet index of 1.31, indicating a potential for milder environmental conditions within the system. The study concluded that the evaluated agroforestry systems have the potential to contribute to soil conservation, adaptation to drought conditions, and climate action in the semi-arid region of Piauí, although their performance depends on environmental and geographic characteristics as well as the management strategies adopted. As a technological contribution, the research developed the Caderno Agroflorestal da Caatinga (CAFE-Caatinga), a web-based tool designed for the recording, monitoring, and integrated diagnosis of indicators regarding carbon, water availability, and productivity in agroforestry systems, thereby expanding decision-support capabilities for producers, technicians, and researchers.