Trees play an invaluable role when it comes to helping pollinating insects – and they benefit all kinds of other wildlife too
When we imagine a pollinator-friendly garden, packed with nectar-rich plants to provide food for bees and butterflies, we often think of flowers. But trees can be just as useful for insects – and they benefit all kinds of other wildlife too.
In the face of the climate and nature crises, we need trees more than ever – but the UK is one of the least wooded countries in Europe, and our trees continue to be under threat.
Planting a tree in your garden or community green space is one of the best things you can do to boost biodiversity. Trees also help to absorb carbon dioxide – so planting a tree, or protecting trees that are already growing, can really help the environment.
And it's well known too that access to green spaces –and, in particular, trees – can improve people's mental health and general wellbeing.
When it comes to helping pollinating insects, trees pack a punch – because of their size, the large quantity of nectar-rich blossoms means that bees, bumblebees and butterflies don't have to travel far to find plenty of food.
It's not just about the blossom though. Trees help pollinating insects and other wildlife in all sorts of ways. Branches and bark offer homes for invertebrates or larger animals and birds. Leaves provide food for many creatures, including moth and butterfly caterpillars, and berries are an important source of nutrition too, particularly for birds. And the leaf litter that builds up under trees can create a safe place where toads and hedgehogs can shelter or hibernate.
Most native broadleaved native trees will benefit pollinating insects – as well as other wildlife – but here are nine species we think are particularly useful. And from the small, shrubby elder to the mighty oak, there's a tree to suit every situation.
Hawthorns are wonderful for wildlife, supporting a wide range of species – including more than 300 insects.
Hawthorn blossom – or May blossom – is a source of food, providing nectar for bees and other pollinating insects. And hawthorns are an important food plant for the caterpillars of several different moth species.
The thorny branches provide protective shelter for birds and other creatures. Birds such as thrushes, as well as small mammals, feed on the berries.
Oak trees can live for centuries – and during their lifetime they can support thousands of different wildlife species.
Oaks flower in April and May, producing pollen that's a food source for bees – including the rare oak-mining bee, which relies almost exclusively on oak pollen for food. Purple hairstreak butterflies and dark-crimson underwing moths (another rare species) also feed on the flowers.
These majestic trees attract a wealth of different bird species such as woodpeckers and tree creepers. The acorns are collected by squirrels and jays.
Oaks are big trees, so they need plenty of space. As an oak tree grows bigger, cavities may appear in the trunk and larger boughs – these can provide homes for birds or bats. A mature oak tree will provide decaying and deadwood habitats for numerous invertebrates like stag beetles and click beetles, as well as supporting fungi, lichens and mosses.
Rowan is a medium-sized tree that produces red autumn berries. These are loved by blackbirds and members of the thrush family – including redwings and fieldfares, which visit in the winter months.
Moth caterpillars eat the leaves and berries of rowan trees, and the flowers provide pollen and nectar for bees and other insects.
Rowan trees are believed to ward off evil, so planting one in your garden could protect you and bring you good luck! Also known as mountain ash trees, they are very hardy and therefore well-suited to upland areas and cold, exposed sites.
Apple trees provide a rich and varied habitat for all sorts of wildlife. Bumblebees love apple blossoms, and can often be seen buzzing from bloom to bloom on a warm spring day. The nectar is enjoyed by all sorts of other insects too.
According to the , 90% of the UK's traditional orchards have been lost since the 1950s – a great shame as well-managed orchard areas are fantastic for wildlife, creating a mosaic of habitats to benefit all kinds of creatures.
Woodpeckers, redstarts and bats can be found in orchard areas. Windfalls attract thrushes, fieldfares and blackbirds, as well as mammals such badgers, hedgehogs and hares. Butterflies, beetles and wasps are also attracted to fallen fruits.
Fruit trees age in a particular way, creating hollows in trunks and cracks in bark. These holes and fissures provide a valuable habitat for all sorts of invertebrates and fungi. As holes become bigger, they can support bats, birds and small mammals.
Apple trees come in a range of different sizes. Choose a dwarfing rootstock, such as M26, for smaller areas or M106 to produce a larger tree.
And a huge benefit of an apple tree is that you get to enjoy the fruits each autumn! There are many different apple trees to choose from, from heritage varieties such as Egremont Russet or Ashmead's Kernel, to more modern varieties that offer excellent disease resistance and bumper harvests.
Hazel catkins appear in mid-February, at a time when there aren't many flowers about. This makes them an excellent early source of nectar for bees emerging from hibernation.
Hazel leaves are eaten by many moth caterpillars, and ground-nesting birds such as yellowhammers, nightjars and willow warblers may shelter in coppiced hazel trees.
Hazel trees are also associated with the endangered hazel dormouse. This tiny mammal eats the hazelnuts in autumn, fattening themselves up to survive hibernation. They also eat the caterpillars that feed on hazel leaves.
Hazel is a medium-sized tree that grows well in poor soil, and can be planted as part of a mixed native hedge. The long straight branches can be cut and used as bean poles in the vegetable garden.
In May, elder produces foamy white discs of blossom – these are a good source of nectar for a wide variety of insects. The caterpillars of several different moth species feed on the leaves.
In autumn, the flowers develop into bunches of small, almost black berries. These are eaten by birds and mammals, with dormice and bank voles enjoying both the flowers in spring and the berries in autumn.
Elder will grow almost anywhere, although it prefers rich soil. Elder is also a useful plant for foragers. The blossoms can be made into elderflower cordial, and wine or syrup can be made with the berries – although be aware that the raw berries (as well as all other parts of the plant) are mildly poisonous.
Blackthorn is one of the earliest trees to flower, its white blossoms appearing in March – this makes it a useful source of early nectar for bees.
Blackthorn blossoms appear before the leaves. This makes it easy to distinguish from hawthorn, the leaves of which emerge before the flowers.
Blackthorn leaves are a food plant for the caterpillars of various moths, including magpie, swallow-tailed and yellow-tailed. It's also eaten by the caterpillars of brown hairstreak butterflies.
As anyone who has foraged for sloes (for making wine and gin) knows, the thorns on blackthorn are long and sharp. These spikey branches provide excellent protective cover for nesting birds – and birds will feed on the sloes in autumn. For the same reason, blackthorn is an excellent addition to a protective hedge boundary, as it will deter intruders.
Holly flowers bloom from early spring, providing nectar and pollen for pollinators like bees and bumblebees. Holly blue butterfly caterpillars eat the leaves, and the leaves are a food source for various moth caterpillars too.
The winter berries of holly are a vital source of nutrition for birds – you may see blackbirds, redwings and fieldfares feasting on the fruits. Small mammals such as dormice and wood mice eat the berries too.
With its tough, impenetrable leaves, holly offers a safe nesting site for all kinds of birds including dunnocks, finches and goldcrests. Hedgehogs, toads and slow worms hibernate in the deep leaf litter that builds up underneath the tree.
Holly is another useful plant to add to a mixed wildlife-friendly hedge, and it grows well in any type of soil, in full sun or shade.
Silver birch is an attractive, medium-sized tree with a beautiful silvery bark that looks stunning in winter. The golden autumn foliage is very pretty too.
Silver birch trees provide food and habitats for hundreds of insect species. The trees produce yellow catkins in March and April – these are a good source of nectar and pollen for bees. Silver birch is also a good source of food for shield bugs.
Aphids feed on the leaves – and this attracts many beneficial insects such as ladybirds. The leaves are also a source of food for moth caterpillars.
Siskins and redpolls feed on silver birch seeds, and the trunks of mature trees offer homes for hole-nesting birds such as woodpeckers.
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Little Green Space February 2022