Property size linked to deforestation, fragmentation and forest fires in the Brazilian Amazon

Deforestation and forest degradation within Brazilian Amazonia primarily occur on private lands, yet their extent varies considerably among properties. We combine high-resolution remote-sensing and land-ownership data to analyse relationships between property size and forest retention, canopy height, fragmentation and fire prevalence across 30,022 private properties within an > 113,000 km 2 consolidated agricultural frontier. Bayesian geospatial regressions showed that larger properties retained a greater proportion of forest overall and within Riparian Protected Areas and were more likely to adhere to Legal Reserve requirements. Properties > 1000 ha contained 75.2% of all remaining forest, while ≤ 150 ha properties accounted for the largest shares of total deforestation (27.6%) and riparian losses (39.9%). Smaller properties were also associated with lower-stature forest canopy, higher forest fire densities, and greater landscape-scale (∼100-km 2 ) fragmentation, primarily due to increased disaggregation of forest among, rather than within, landholdings. Smaller properties thus not only retained less forest, but this forest was more degraded, underscoring the need to tailor policy interventions within Brazilian Amazonia according to property size. Targeted subsidies and credit schemes could enable smallholders to farm a smaller portion of their land, restore forest and reduce reliance on degrading land-use practices (e.g., fires). Fines, embargoes, and stricter Forest Code enforcement may help preserve remaining forest and reduce fire use in largeholdings. Incentivising forest restoration across property boundaries, and offsetting forest cover deficits to remaining continuous forest tracts, would help minimise fragmentation. Implementing these measures will depend on collaboration between government agencies and NGOs to align enforcement, financing, and coordinate landscape-scale management.