Coordinated volatile isoprenoid production and leaf turnover protect central Amazon Forest trees against stress

Climate stress is shifting the Amazon Forest from a carbon sink to a source, highlighting the need to understand tree resilience strategies, including leaf turnover and volatile isoprenoid (VI) production. Dry-season leaf turnover in Amazonian trees is hypothesized as a strategy to avoid drought and herbivory, and VIs protect trees against abiotic and biotic stresses. We measured temperature- and light-driven changes in VI emissions and characteristics of photochemical activity in 12 brevideciduous and evergreen central Amazon woody species. Brevideciduous trees showed greater increases in sesquiterpene emissions with rising temperature. Among these, isoprene emitters showed superior baseline photosynthetic performance, suggesting coordinated VI production and leaf turnover strategies. Moreover, current global VI models consistently overestimated isoprene fluxes by neglecting leaf phenological variability. These findings reveal overlooked phenological controls on Amazonian VI emissions, challenging standard model parametrization and emphasizing leaf-level data to improve predictions of atmospheric chemistry and climate-vegetation feedbacks.