It’s a 66m-year-old decision. Some trees got there much quicker; some took a little longer. But most of the broad-leaved trees that we know and love – the magnolias, plane trees, elms, beech, walnuts, limes, oaks, maples and horse chestnuts – made a calculated decision to drop their leaves come autumn. Large, soft leaves are hard to protect in the winter weather, so the trees evolved to lose them, but not their valuable resources.
Leaf fall is a precision art for a deciduous tree – it’s a salvage operation on the greatest scale as the tree works quickly to bank the resources hidden inside the pigments of the leaves. The greens of chlorophyll go first, then the yellows of the xanthonoids, and then the orange carotenoids, until all that is left is brown – at which point the tree lets its foliage go.
