Climate warming extends growing season but not reproductive phase of terrestrial plants

Aim: Understanding how plant phenophases respond to climate warming is key to prediction of future ecosystem dynamics. Although warming has lengthened the growing season of plants in most terrestrial ecosystems, little is known about the contribution of different phenophases to this extension. Location: Global terrestrial ecosystems. Time period: Data collected from 1979 to 2020. Major taxa studied: Terrestrial plants. Methods: Here, we conducted a global meta-analysis, compiling 772 pairs of observational data from 42 warming manipulative experiments to investigate the temperature sensitivity (expressed as days per degree Celsius) of the durations of different phenophases across major natural terrestrial ecosystems. Results: We found that the durations of flower bud, flowering and fruiting and the total reproductive phase did not exhibit any significant change in response to experimental warming across all terrestrial plants, although large variations in temperature sensitivity of the reproductive phenology existed. The temperature sensitivity of reproductive phases was influenced by the taxa of plants. Specifically, the flower bud duration of C₄ plants had a higher temperature sensitivity than that of C₃ plants, and the flowering duration in woody plants exhibited a marginally higher temperature sensitivity than in herbaceous plants. In contrast to the small responses of the reproductive phases, the growing season lengthened under experimental warming. The temperature sensitivity of the growing season length was strongly affected by the magnitude of warming, showing a slower lengthening of the growing season with larger increases in temperatures. Main conclusions: These results suggest that, under future warmer climates, terrestrial plants will allocate more time to growth than to reproduction; however, the warming-induced extension of the vegetative phase might slow down over time.