However, climate warming is affecting the timing of the seasonal cycle. Spring leaf-out tends to happen earlier. Researchers have also predicted that warming will cause autumn senescence to happen later, but is that really what happens? What are the factors regulating the timing of autumn? In order to understand how the timing of autumn leaf senescence may shift under future climate conditions, our lab had a closer look at the underlying environmental triggers.
MethodThe Phenological observations
The citizen science program, Pan European Phenology Project, provided us with a database of phenological observations of spring leaf out and autumn leaf senescence. In total, we analysed over 434,000 phenological observations of six deciduous tree species across Central Europe, from 1948 to 2015. We assessed the effects of several environmental factors - including spring leaf out, spring and summer photosynthesis, temperature, and precipitation - to evaluate the mechanisms governing the timing of the autumn senescence.
MethodLab experiments and modelling
To improve confidence in future phenology and carbon cycling forecasts, we developed a new autumn phenology model, explicitly accounting for both seasonal carbon uptake and autumn environmental cues, by incorporating mechanistic representations of these drivers.