FIRE REGIME AND LAND COVER IN SERRA DAS CONFUSÕES NATIONAL PARK (NORTHEASTERN BRAZIL)

Strictly protected areas are the main instrument against native vegetation loss, but their capacity to contain fire in semiarid regions is rarely quantified with a design that separates the effect of protection from that of climate. We evaluated Serra das Confusões National Park (PNSC; created in 1998 and enlarged in 2010 to 8,238 km²), in the Caatinga–Cerrado ecotone of Piauí, using 41 years (1985–2025) of MapBiomas burned area and land cover, compared with external rings of 0–20 km and with pixels matched by vegetation, elevation and slope. The enlargement of the park in 2010 served as a natural experiment. Between 1999 and 2010, the annual burn probability in the original park was 6.4 times lower than in comparable surroundings (0.31% vs. 2.02%; 95% CI: 4.6–9.8), a difference absent before its creation (ratio 1.3; 0.8–2.0). During the 2011–2025 drought, fire penetrated through the edges and the ratio fell to 1.7, with a clear depth gradient (savanna: 5.2% at 0–3 km from the edge and 1.1% at 10–20 km). Park cover remained stable (62% forest, 36% savanna), whereas in the surroundings 824 km² of savanna were converted to pasture and agriculture, a conversion not associated with fire frequency. Forest-to-savanna conversion increased with burn frequency, from 0.2% to 11% of park pixels. The park contained fire and the conversion of native vegetation, but not the anthropogenic pressure from its surroundings or drought.