Widespread greening transitions and their drivers across the Cerrado ecoregion

Global environmental change is pushing ecosystems towards fundamental, often irreversible transitions. These transitions are expected to become more frequent, resulting in disruption of ecosystem benefits that we rely on. While proven theoretically, there has been variable success in detecting such transitions and their drivers using real world observations, especially in complex tropical landscapes including tropical savannas. Here we determine ecosystem transitions and their drivers across South America’s largest savanna biome, the Cerrado ecoregion in Brazil between 2001–2021, which contains grasslands, savannas and forest vegetation formations. Our results reveal a staggering 94.6% of native vegetation area has undergone transitions, with three fourths exhibiting a greening pattern. Critically, around 90% of the transitioned areas are rapid regime shifts, mostly occurring during the 2017–2018 La Niña years. While long term hotter and more seasonal climate generally promote greening across all vegetation formations, we find distinct ecological impacts for the remaining drivers. Increasing climate extremes, specifically drought conditions significantly suppress greening in savanna formations only, whereas altered fire regimes inhibit greening transitions in grasslands only. Despite widespread greening, anthropogenic pressures reduces the probability of greening transitions across all native vegetation formations. Though woody encroachment is the most common greening transition examined across tropical savannas globally, we posit that it is an unlikely explanation for the rapid regime shifts across the Cerrado , based on the rapidity of the transitions. Hence, questions remain regarding the causal mechanisms of greening transitions, especially rapid regime shifts, across the heterogenous and species rich Cerrado ecoregion. Our findings of the nature and drivers of ecosystem transitions will aid the design and implementation of environmental policies and conservation interventions aimed at supporting a resilient Cerrado and indeed all ecosystems.