Forests, both temperate and tropical, cover around 30% of the world’s surface, so, unsurprisingly, are home to 80% of terrestrial organisms. Trees provide wildlife with food, shelter, water and nesting sites, and in return, wildlife provides crucial services, such as pollination, seed dispersal and pest control.
Trees are not only home for thousands of species, but they’re also essential to humans, too. Currently, three hundred million people are known to live in forests worldwide. The relationship between humans and trees dates back thousands of years, and are still pivotal to many people's livelihood today.
In every tree, you’ll find a unique community of wildlife that works together in unity, maintaining the status quo. But how exactly do trees help wildlife?
Trees provide food for wildlife
Wildlife use trees in many different ways, one being as a food resource. Most parts of a tree can be utilised by wildlife; seeds, buds, leaves and even the bark of a tree, can be eaten by bacteria, fungi, insects, birds and mammals.
Living things have co-adapted with trees for millions of years so that they can benefit from one another. For example, treecreepers have curved beaks to pluck insects from bark, while deer have wide, flat teeth for grinding plant matter.
The Short Toed Treecreeper, native to Europe, has evolved a curved beek to get food from bark
Trees as food for insects
The blossoms of trees attract millions of insects every spring and summer, as an invaluable resource for pollinators. This relationship between insects and trees has been evolving since the Cretaceous period when insects first began transporting pollen in return for food.
The relationship between insects and trees doesn’t stop here. Trees are essential for many species of butterfly, moth and beetle. In most cases, insects need trees to complete their life cycles. Tree foliage is the main source of food for the caterpillars of many species of moths, butterflies and sawflies. Birch
are just some of the trees favoured by native insects.
When we think about insects, the word pest often springs to mind. Although, trees full of native caterpillars, flies and other bugs are often a sign of good tree health. The more insects in your garden trees, the more birds, bats and mammals will take residence. These will both maintain the insect levels in your garden and help to disperse seeds from fruits and berries.
A songbird perched in a tree full of berries
Trees are vital habitats
It is easy to look at a tree as one single habitat, however, one tree actually creates many different microhabitats. For example, wood mice dig their burrows in the soil under tree roots while blackbirds use the canopy to build nests.
Bark as habitat
The bark alone provides a foundation for lichen and mosses to flourish, which when viewed under a hand lens, appears like a whole other world. Climbing plants like Ivy
, or fungi such as Bracket Fungus, cling to the trees' trunks, providing further habitat for insects and songbirds to shelter.
Even the cracks of tree bark alone form a haven for Arthropods, such as millipedes
and spiders. Sometimes, bark provides the perfect roost for tiny pipistrelle bats, which find the rot holes and loosened bark of trees particularly attractive. Tree hollows created by adverse weather, diseases and pests, are quickly adopted by owls, woodpeckers and kingfishers.
Dead wood as habitat
Trees not only provide habitats for wildlife when they’re alive, but they’re also extremely useful when they’re dead, too. Dead wood is one of the most important, and under-rated habitat types, providing shelter for countless invertebrates. The insects and fungi which aggregate on dead wood not only help fallen trees decompose and break down but make the perfect banquet for mammals, birds, reptiles and amphibians.
For many beetles, dead wood is necessary for survival and development. The greater stag beetle
spends around three to four years feeding on dead wood below the ground as a grub. Dead wood also plays a large part in the life cycle of bees, too, which is where carpenter bees
get their name. It’s not just carpenter bees that use tree materials for their nests. Tree bumblebees
and wild honey bees
will readily build nests in trees, too.
A greater stag beetle pictured on dead wood
Trees keep our ecosystem healthy
Trees improve air quality and help to recycle nutrients
Ecosystem services are the environmental benefits produced by living things. Not only do trees produce oxygen and improve air quality, but they also play a huge role in the movement and recycling of nutrients in the environment. Similarly, forests absorb large amounts of carbon dioxide during photosynthesis, making them carbon sinks. This means they absorb more carbon than they release.
Trees help to prevent soil erosion
Trees also play a large part in preventing soil erosion. Soil erosion is when the important layer of topsoil is washed away by rainfall or wind. Tree roots help to prevent this by locking in the soil, absorbing excess water and releasing it back into the air through transpiration.
They can also reduce wind and rain damage by acting as physical barriers. By obstructing strong wind currents and heavy rainfall, they reduce the overall impact of erosion, preventing surface runoff and helping to prevent flooding.
Trees help stabilise the environment
In addition to being beneficial to humans, ecosystem services help to maintain stable environments in which wildlife can flourish. Various species have spent hundreds of thousands of years evolving to adapt and thrive in a specific environment and for animals that are sensitive to change, the maintenance of consistent environmental conditions is crucial.
A picture of a tree trunk with a bracket fungus
Trees increase biodiversity
Biodiversity is a word used to describe and measure the variety of living things in an environment. Biodiversity is everywhere we look, and generally the more species the more healthy and functional the ecosystem.
High biodiversity means that an ecosystem is more resilient to disturbance and has more stable food webs, which ultimately promotes the production of natural resources.
Different types of trees and woodland have varying effects on biodiversity. For example, conifer woodlands generally have lower biodiversity, whereas ancient woodland supports more species than any other type in the UK.
Global biodiversity is declining at an alarming rate. This is why it’s crucial we not only plant more trees but protect our existing woodlands – preserving these fragile ecosystems for both people and planet. Each tree is not sufficient to sustain large wildlife populations on its own, and having substantial areas of consistent habitat is vital to allow animals to move freely, reproduce and utilise natural resources.
A tree branch covered in lichen, moss and tiny Cannon Fungi
5 ways trees can help wildlife in the garden
If we all made our gardens and outdoor spaces a little more wildlife-friendly, we can make a massive difference! Here are some quick tips to help you out:
When choosing a tree for your garden, trees such as Cherry
are great for spring blossoms. They will look beautiful, and provide lots of food for pollinators, too.
Fallen fruits left on the floor provide food for butterflies and moths in autumn.
During autumn, fallen leaves can be raked into a small corner to provide refuges for hedgehogs and hibernating insects. When leaves begin to break down they’re used as food by Earthworms
and other decomposing insects in the ground!
4) Dead wood
Dead wood is an invaluable habitat for hedgehogs, reptiles, amphibians and insects. Following pruning, why not leave the cut branches in a pile in a corner of your garden? Alternatively, cut branches are perfect for path edging, and stumperies are enjoyed by many species of native beetle.
5) Trailing plants
Tree trunks are the best natural plant supports. Why not encourage Ivy
to climb? Ivy is one of the best plants you can have in your garden for supporting pollinators in the autumn; providing fruits for birds in winter.
Don’t have a garden?