Trust in nature – and stop raking up your garden leaves

 

 

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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.

But the spent leaves that flutter to the ground aren’t a waste product. They are rich in carbon and play an essential role for the tree and the ecology it supports. The leaves act as a physical barrier for soil, keeping it and its many microbes insulated, and also for the tree roots, as the wet mats of autumn leaves shelter the fragile top layer from the drying winds.

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