Alys Fowler
is an ecological gardener and writer based in Mid-Wales. A lot of what she grows, she eats – the rest, everything else eats! @alysf
They are called leaves for a reason;
to be left alone to do their essential work. They may look spent, but their business is far from done, both for the plant they left and the wider world around them.
Leaf drop is an ancient adaptation. There’s fossil evidence for it first appearing around 100 million years ago, during the Late Cretaceous period – that’s a lot of time to perfect something – whereas the lawn was an 18th-century invention to show off wealth. Leaf drop is the plants’ way of terraforming the soil they need to thrive in. Soil can hold up to 30 per cent more carbon if the autumn leaves are left to rot. Carbon feeds the soil food web, particularly mycorrhizal fungi, which improves not only the trees’ ability to take up minerals and water, but also the lawn and the wider garden. Rotting leaf litter improves soil structure too, helping the soil’s water-holding capacity in periods of drought, while also creating the kind of porosity that helps with flood management.
“Soil can hold up to 30 per cent more carbon if the autumn leaves are left to rot. Carbon feeds the soil food web”
Leaf litter plays another role; it is a key overwintering habitat for insects, particularly moth and butterfly cocoons, but also beetles and worms. The majesty of an elephant hawk moth, all neon pink and olive, exists because of the leaf litter in which it pupated. The angle shades, the brown-tail, the wood white; so many of our summer beauties require leaf litter.