Warming may extend tree growing seasons and compensate for reduced carbon uptake during dry periods

Warming and drought alter plant phenology, photosynthesis growth with important consequences for the global carbon cycle earth's climate. Yet, few studies have attempted to tease apart their effects on tree particularly leaf senescence, source sink activity. We experimentally assessed single combined of warming reduced soil moisture phenology (leaf-out senescence date, growing season length) above-ground (height diameter growth, area Huber values) activity (net photosynthesis, photosynthetic efficiency, chlorophyll concentration total [C] uptake) two species distinct strategies deal drought: European beech pubescent oak. advanced leaf-out, irrespective levels, in oak a lower extent beech, leading prolonged but not beech. No impacts timing were found both species. Reduced had little impact Warming-induced advances higher efficiency increased annual C uptake compensated presence moisture. Conversely, activity, including yearly uptake, was all treatments than control, indicating no compensation budget by phenological shifts. Synthesis. Our results demonstrate that warming-driven earlier compensates during hot dry periods, only oak, which is rather drought-tolerant Current predictions warming-induced mitigation through extended seem incorrect