PubMed · 2026-05-22
European beech trees don't respond to temperature the same way all season long — warming in spring pushes their leaves to drop earlier in fall, while warming in late summer delays that drop. A new study shows the 'flip point' between these two effects isn't fixed to the summer solstice but shifts depending on how fast the tree developed earlier in the year.
Pre-solstice warming advances autumn leaf senescence (earlier leaf drop), while post-solstice warming delays it — confirming a seasonal 'switch point' in beech phenological response
The switch point is not fixed at the summer solstice (June 21) but shifts based on early-season developmental rate, occurring at a 'compensatory point' between spring development and late-summer temperature effects
Climate manipulation experiments on potted European beech demonstrated that developmental constraints — not temperature alone — govern when trees transition from growth to dormancy preparation
