Plant phenology is the study of the timing of natural plant processes, such as leaf sprouting, flowering and leaf shedding in autumn. These seasonal changes are influenced by environmental conditions, particularly temperature and daylight hours.

In the context of climate change, plant phenology is particularly significant because these events are changing. For instance, many plants are flowering earlier in spring due to rising temperatures; some extend their lifespan into autumn. Tracking these changes helps scientists to understand how ecosystems are responding to climate change. This can affect agriculture, biodiversity and the timing of food availability for animals and humans.