We want to test if leaf senescence is triggered by the timing of tree growth cessation, and whether this occurs only when day length has shortened sufficiently. Five sub-hypothesis will be tested:
- The onset of leaf senescence is determined by day length if trees stop growing early because of unfavourable environmental conditions (for example drought, poor site fertility, bad weather).
- The start of leaf senescence is determined by the timing of growth cessation when trees are not limited earlier by unfavourable environmental conditions.
- This mechanism applies to both young and mature trees.
- This mechanism applies to all species and genotypes at different latitudes.
- The proposed mechanism captures the timing of leaf senescence recorded across the major temperate and boreal forested areas of Europe.