Decoupling between ecosystem photosynthesis and transpiration: a last resort against overheating

Abstract Ecosystems are projected to face extreme high temperatures more frequently in the near future. Various biotic coping strategies exist prevent heat stress. Controlled experiments have recently provided evidence for continued transpiration woody plants during air temperatures, even when photosynthesis is inhibited. Such a decoupling of and would represent an effective strategy (‘known as leaf or canopy cooling’) lethal temperatures. At ecosystem scale, might dampen development propagation extremes despite further desiccating soils. However, at occurrence this still limited. Here, we aim investigate mechanism using eddy-covariance data thirteen ecosystems located Australia causal graph discovery algorithm. Working half-hourly time resolution, find four which can be classified Mediterranean woodlands. The occurred above 35 ? C. nine other investigated sites, found that vegetation CO 2 exchange remained coupled observed Ecosystem characteristics suggest energy balance plays crucial role determining decoupling. Our results highlight value causal-inference approaches analysis complex physiological processes. With regard increasing especially events future climates, types pushed threatening findings coupling leaf-level stomatal conductance, common land surface schemes, may need re-examined applied high-temperature events.