Extensive 21st-Century Woody Encroachment in South America's Savanna

Woody encroachment is occurring in all tropical savannas of the world. However, in the Brazilian savanna (the Cerrado), the extent of this phenomenon is still poorly documented. Here woody encroachment was quantified throughout the Cerrado biome and transitional ecotones using a trend analysis of the annual maximum of enhanced vegetation index obtained from the Moderate Resolution Imaging Spectroradiometer. The associations with potential local drivers, such as fire and land use regime, were assessed using satellite data of land cover and fire regime. We found that 19% of the remaining native vegetation showed significant evidence of woody encroachment in the last 15 years and 7% exhibited degradation processes. The local factors that favored woody expansion in 19% of the biome were a decrease of fire (34%) and land use abandonment (26%). Our study highlights that local human-associated drivers are playing a major role in woody encroachment and savanna degradation.