Contrasting responses of early- and late-season plant phenophases to altered precipitation

Precipitation is a key driver of plant phenology in addition to temperature and photoperiod. Although a few studies have explored phenological responses to altered precipitation, the general patterns of sequential phenophase responses and their potential drivers remain elusive. Here, we conducted a meta-analysis of the responses of ten phenophases to altered precipitation from 63 manipulative experiments. We show that early-season (leaf out, first flowering, last flowering and first fruiting) and late-season phenophases (last fruiting and leaf colouring) shifted in opposite directions with precipitation changes. Advanced early-season phenophases and delayed late-season phenophases led to extensions of the reproductive phase and growing season with precipitation increases. Similarly, delayed leaf out and advanced leaf colouring resulted in a shorter length of the growing season with precipitation decreases. We further found that the responses of phenophases were less pronounced in wetter regions than in drier regions, regardless of the precipitation increase or decrease treatments. In addition, the phenophase responses were mediated by the seasons when the precipitation changes were imposed. For instance, early-season phenophases were more responsive to winter or spring precipitation increases, but late-season phenophases were only significantly affected by spring-autumn precipitation increases. These findings will help improve the forecasts of plant phenological responses to precipitation changes and will assist in the incorporation of precipitation representations into next-generation phenological models.

Automated summary

Precipitation is a key driver of plant phenology, and our meta-analysis of 63 manipulative experiments shows that early-season and late-season phenophases respond differently to precipitation changes. Increased precipitation leads to advanced early-season phenophases and delayed late-season phenophases, resulting in longer reproductive phases and growing seasons. Decreased precipitation, on the other hand, leads to delayed leaf out and advanced leaf colouring, shortening the length of the growing season. These responses are less pronounced in wetter regions and are influenced by the seasons when precipitation changes occur.