How do plants age? There is now much knowledge about how a plant’s life cycle stage (or size), and the environmental conditions it experiences, impacts its probability to survive and its reproductive output. This knowledge has helped ecologists understand what drives plant population dynamics and allows predictions of effects of environmental changes on population dynamics and distributions. However, how plant mortality and fertility are affected by age is poorly known, including whether plants generally even show “demographic senescence” (the gradually increasing mortality and decreasing fertility with age observed in several animal groups).
Classical evolutionary theories of aging predict that demographic senescence should occur in all organisms. However, this is not supported results of current age-based plant demographical studies. Within SEAD-Plant we find that plant ageing varies substantially (even regarding whether effects of age are positive or negative for plant fitness) among species, populations within species and even among years, and that interactions between age, stage and environment need to be understood in order to understand the evolutionary drivers of senescence and the drivers of population dynamics. The latter is necessary to make better forecasts of effects of environmental change such as climate change and other global environmental changes, on plant population sizes and distributions.