Evapotranspiration declines prolonged by deforestation and fire in South American biomes

Evapotranspiration strongly couples land and atmosphere to regulate water, carbon and energy fluxes across tropical South America. Ongoing deforestation and fires reduce the capacity of deep-rooted trees to recycle moisture, while intensifying droughts further alter the timing and magnitude of evapotranspiration. Here we present a high-resolution, data-constrained hydrological modelling analysis to isolate the effects of anthropogenic disturbances and droughts on evapotranspiration and vegetation function across the Amazon and adjacent biomes from 2003 to 2020. We find that evapotranspiration declines from deforestation persist 21–22% longer than those caused by fire or drought alone. When these stresses co-occur, evapotranspiration losses intensify by 36% and persist 66% longer than the average impact of individual stressors. Across neighbouring biomes, we find that grasslands and savannas in the Cerrado are most vulnerable to droughts, with evapotranspiration recovery often exceeding seven years, while Pantanal wetlands recover rapidly due to sustained moisture availability. Furthermore, vegetation productivity declines under compounding stresses despite concurrent greening trends. Our findings reveal that recurrent human disturbances erode ecosystem resilience, threatening long-term ecological stability. Isolating the human footprint on evapotranspiration is pivotal to guide sustainable land-use transitions that preserve land–atmosphere coupling in South America’s tropical ecosystems. Human-driven disturbances intensify and prolong evapotranspiration declines across South American ecosystems, disrupting the water balance and threatening ecological resilience, according to hydrological modelling and remote sensing data.