Country diary: Look beneath the leafy lasagne, life is getting busy | Phil Gates

Barnard Castle, Teesdale: In the winter woodland you can find more activity than you might think, including the most numerous animals on Earth

Two o'clock on a cold December afternoon, and the sun is already sinking towards the western horizon, sending long shadows through Flatts Wood. Ahead, a blackbird lands beside the footpath and begins flinging aside dead leaves, with the irascible air of a gardener discovering fly-tipped rubbish on their lawn. During shortwinter days these birds expend a lot of energy excavating layers of decaying autumn leaves, in search of buried food. Head cocked to one side, he seems to be listening, perhaps sensing something hiddenhere, and ignores us until we are a few paces away.

When he flies, we take a closer look: what lives under last summer's discarded foliage? Beneath loose, wind-dried leaf litter lies several years of accumulated dead foliage; a leafy lasagne welded together by fine fungal threads advancing from a spreading delta of pure white mycelium, creeping out from under a fallen branch. For every toadstool that appears above the surface, there will be miles of these fine hyphae, digesting their way through dead plants, until they can store enough energy to organisethemselves into another fungal fruiting body.