Land use transformations and tenure conflicts in the Cerrado-Caatinga frontier: Evidence from Piauí, Brazil

Brazil’s Rural Environmental Registry (CAR), established in 2012 under the Forest Code, is a mandatory environmental cadastral system based on self-declaration of property boundaries that plays a central role in environmental enforcement, rural credit allocation, and land-use monitoring. This study develops and applies a hierarchical conflict-resolution framework to systematically identify which portions of the CAR are procedurally reliable and analytically usable for deforestation attribution and regulatory enforcement. We analyzed 310,657 CAR registrations recorded in 2025 in Piauí, Brazil, integrating them with official tenure datasets through a sequence of hierarchical rules for the Cerrado-Caatinga transition, one of the most active agribusiness frontiers. The reconstructed tenure map, derived from the hierarchical framework representing the accumulated state of all property registrations and boundary rectifications, was applied to attribute deforestation recorded between 2013 and 2023. The primary findings indicate that intra-CAR spatial overlaps were detected nearly one-third of the registered area, with boundary conflicts concentrated among larger properties along the Cerrado agribusiness frontier. In terms of deforestation, 94.20% of vegetation loss (1236,100 ha) can be attributable to identifiable actors, of which 86.60% is associated with private properties registered in CAR and official tenure datasets. The top 1% of properties ranked by cumulative deforestation account for 71.50% of total vegetation loss between 2013 and 2023, indicating a pronounced concentration of clearing among a numerically small set of landowners. Of the deforestation associated with private properties, 73.40% is classified as illegal under the Forest Code mandates applied in this analysis, with Legal Forest Reserve deficit violations representing the dominant source of non-compliance. Although over 13 million ha of native vegetation remains on private lands, Legal Reserve deficits are concentrated among large properties in the Cerrado biome, while small properties show the largest number of individual deficit records. These results demonstrate that a hierarchical analytical framework can extract procedurally reliable information from a self-declared registry, providing a scalable basis for spatially targeted enforcement, deforestation attribution, and Forest Code compliance monitoring at the subnational level.