Why Our Native Trees Punch Above Their Weight

Walk through an ancient oak wood in late May and you will hear the hum before you see the source. That low drone is the sound of a food web in full swing, and almost all of it starts with our native trees. A single mature oak can support more than two hundred species of insect, from the purple hairstreak butterfly to the stag beetle. Compare that with a sycamore or a horse chestnut, which might host a dozen. The difference is not sentimentality; it is millions of years of shared evolution.

Our insects evolved alongside oak, willow, birch, hawthorn and rowan. They learned to eat those leaves, lay eggs in that bark and overwinter in those crevices. When we plant a non-native tree, we are effectively putting out a meal that nothing local recognises. For anyone with a garden, an allotment edge, a paddock or a patch of village green, that is worth knowing before the next trip to the nursery.

The Insect Supermarkets: Oak, Willow and Birch

If you only remember three trees, remember these. They are the cornerstones of British woodland biodiversity, and each does something slightly different.

• Oak — supports over 280 invertebrate species in Britain, including the oak processionary, the purple emperor and countless moths. Its rough bark is a nursery for lichens, and its decaying heartwood shelters bats and beetles.
• Willow — wet-loving and fast-growing, willow supports around 450 associated species when you include the closely related sallows. Pussy willow catkins are one of the earliest nectar sources of the year for emerging queen bumblebees.
• Birch — a pioneer of heath and bog edges, birch feeds the birch shield bug, the scalloped hazel moth and dozens of micro-moths. Its catkins are a spring lifeline for tits and siskins.

Add hawthorn, blackthorn, rowan, hazel, field maple and alder and you have a planting list that will keep a garden or smallholding busy with life for decades.

From Leaves to Birdsong: How the Food Chain Works

The chain is refreshingly simple to follow. Caterpillars and aphids eat leaves. Blue tits, great tits and coal tits eat the caterpillars. Sparrowhawks and tawny owls eat the tits. Meanwhile, bats such as the pipistrelle hoover up moths on the wing, and hedgehogs, shrews and wood mice rummage through leaf litter for beetles and larvae.

Here is the number that surprises most people: a single pair of blue tits will bring between seven and ten thousand caterpillars to their chicks in a single breeding season. That is not a typo. If your garden has no native trees, there is no caterpillar pantry to raid, and the nest box you lovingly hung will fail. Native trees are not decoration; they are the infrastructure of the entire food web.

Planting for Wildlife in a Small Space

You do not need a country estate. A suburban plot, a school field or a strip of churchyard can all pull their weight. What matters is choosing the right species for your soil and situation.

• Heavy clay? Go for oak, field maple or crab apple — all tolerant and long-lived.
• Damp ground or a stream edge? Willow, alder and downy birch will thrive where little else will.
• Light sandy soil? Silver birch, rowan and hawthorn are excellent choices.
• Small garden? Plant a hazel, a rowan or a crab apple. All can be coppiced or kept to four or five metres with careful pruning.
• Windy exposed site? Hawthorn and blackthorn make a sturdy, wildlife-rich hedge that will shelter everything else behind it.

Plant bare-rooted stock between November and March, when the tree is dormant. Water well for the first two summers, mulch with well-rotted manure or bark, and stake only if the site is exposed. Resist the temptation to over-tidy; dead wood and fallen leaves are habitat, not mess.

Look After the Old Ones Too

New planting is wonderful, but do not overlook what you already have. A veteran oak or a gnarled willow pollard is an ecosystem in itself, with hollows, decay columns, sap runs and dead branches that no sapling can replicate. If you have one on your land, protect it. Fence it off from livestock, avoid compaction around the roots and resist the urge to fell a limb that looks untidy.

Conservation charities and local wildlife trusts often run free advice sessions on veteran tree management. It is worth asking before you reach for a saw. A tree that has stood for three hundred years is not easily replaced.

The Long Game

Planting a native tree is an act of optimism. You will not see the full benefit in your lifetime, but the insects will arrive within two or three years, the birds shortly after, and the bats once the canopy closes. Within a decade, a modest garden rowan can be feeding redwings in winter and blackcaps in autumn.

Whether you have ten acres in Devon or a small patch in a market town, the principle holds. Choose native species, plant them well, leave the leaf litter alone and let the food chain do the rest. Our countryside is quieter than it was thirty years ago, but the remedy is in our hands, one oak, one willow, one birch at a time.