Does Melliferous Reforestation Restore Soil Carbon Stocks in the Brazilian Semi-Arid?

In the Brazilian semiarid region, reforestation with melliferous species has been adopted by beekeepers as a land-use strategy that supports apiculture while promoting soil organic carbon (SOC) recovery in degraded areas. This study assessed the effects of land-use change on SOC stocks under three systems: reforestation (Mimosa caesalpiniaefolia, Leucaena leucocephala, and Moringa oleifera), pasture and native vegetation, in smallholder farming systems in Piauí State, Brazil. The study was conducted on four rural properties with contrasting soil clay contents, ranging from approximately 6 to 15%, each containing the three land-use systems. Soil samples were collected from the 0–40 cm layer during dry and rainy seasons and total SOC stocks were quantified. In areas with higher clay content (≈14–15%), SOC stocks under reforestation were similar to native vegetation and higher than pasture. In these areas, reforestation reached up to 28.1 Mg ha⁻¹, while pasture ranged from 18.5 to 25.4 Mg ha⁻¹. In contrast, in areas with lower clay content (≈6–7%), pasture systems exhibited higher SOC stocks, reaching 18.6 Mg ha⁻¹, compared with reforestation and native vegetation. These patterns reflect differences in soil texture and clay-mediated stabilization capacity following land-use change. Overall, reforestation with melliferous species can increase or maintain SOC stocks in the Brazilian semiarid region, particularly in soils with greater potential for organo-mineral associations. In coarse-textured soils more susceptible to degradation, reforestation alone is insufficient to maximize SOC stabilization, requiring complementary conservation practices to enhance organic matter inputs and soil protection over long-term temporal scales.