Choosing Tree Species for Wildlife (Part 1)
By Stephen Melhuish
One tree is not just a single thing: trees connect with the environment and add to the habitat in which they’re planted. A single tree grows and changes (adding girth to its trunk while spreading its branches and putting on leaves), flowers, and is pollinated (producing fruit and seeds) during autumn. Trees then change colour and drop leaves that decay, in time helping increase fertility in the soil beneath.
Autumn is a time when we take stock in the garden, allowing ourselves to look back at what worked in the space, to see if we can make further changes and to form the following year’s landscape.
Gardens are so individual to us gardeners, but to wildlife, they are an environment where a whole life cycle can be established. When you choose a tree to plant, you’re actually buying into a whole host of wildlife choices. Each tree attracts different levels of insects, mammals and invertebrates. The numbers of each varies hugely, but one thing is certain, the environment will be massively improved by its addition.
In this article, I hope to focus on just a few of the wildlife aspects per species that are so incredibly important to everyday existence.
Autumn and winter is a perfect time to choose trees for planting while the roots are dormant.
Malus (Crab Apples)
These are especially good and already well known for keeping wilder hedge rows active for pollinators. Fruit growers in the UK will plant them nearby to help pollinate their commercial apples, pears and other fruit.
Those that are fully feathered (with branches closer to the ground) will help insects that require lower flower nectar. This sugary food gives each tiny visitor energy and thus increases the ability for each one to continue flying further and therefore expanding the range of pollination.
Animals that benefit:
- Birds will feed on the fruit, particularly robins, starlings, green finches and thrushes.
- The colourful flowers will attract bees in spring.
- Many mammals such as foxes and badgers, will enjoy the fruit.
- The native crab apple can be home to over 90 insect species.
Due to its spreading and arching habit, the branches can create shelter and keep an area wilder for much-needed increase in habitat. Its arching form also means that branches growing closer to, or touching, the ground can increase the chances for foraging insects to reach their nectar. The profuse, sweet-scented flowers are borne in early summer, followed by autumn scarlet berries – another reason for its inclusion is as an addition to a re-wilding option. This form, therefore, encourages diversity of habitat where its planted. It’s also suitable and successful for inclusion as part of a wilder hedge or tree line.
Benefits to animals:
- Larval food for butterflies and moths like the grey dagger, mottled umber, short-cloaked moth, the winter moth and the hawthorn moth.
- The flowers attract bees and the berries are eaten and much loved by birds, especially blackbirds, thrushes, waxwing and pheasant.
A hawthorn hedge is fast-growing and sturdy, and can be ‘laid’. These grow in almost any soil.
Benefits to animals:
- Heavily scented white flowers in early spring are much loved by bees and other insects.
- The rich bright red berries, called ‘haws’ are a favourite food in winter for many birds including fieldfares and redwings.
- The hawthorn has 149 associated insect species as well as over 300 other species.
The plant is tolerant of shade and heavy clay soil.
Quercus robur (and all other oaks)
A single oak can support more than 1,000 other species. Insects, including butterflies, birds and bats all rely on the oak. It has 284 species of associated insects alone. Although lofty at full height, this tree can be pollarded, or coppiced, and can also be ‘laid’ to make a hedge. It’s very long-lived, making it a truly wonderful addition to any wildlife consideration.
Oak forests support more life forms than any other native forest. They are host to hundreds of insect species, supplying many birds with an important food source. In autumn, mammals such as squirrels, badgers and deer feed on the acorns.
Benefits to animals:
- Flower and leaf buds of English oak are the food plants of the caterpillars of purple hairstreak butterflies.
- The soft leaves of English oaks break down with ease in autumn and form a rich leaf mould beneath the tree, supporting invertebrates such as the stag beetle, and fungi, like the oakbug milkcap.
- Holes and crevices in the tree bark are perfect nesting spots for the pied flycatcher or marsh tit.
- Bats also roost in old woodpecker holes or under loose bark, as well as feeding on the rich supply of insects in the tree canopy.
Holly (Ilex aquifolium)
Next, we look at the Holly, which provides shelter, protection and berries during winter. It is important to note that you should have both a female and a male tree for the development of berries, these need to be within 50 feet of each other.
Benefits to animals:
- It is the food plant for first-generation holly blue butterflies in spring.
- 36 species of insect have been recorded feeding on holly (two are exclusive).
- The small, pale green, scented flowers attract butterflies, bees and other insects in late spring / early summer.
- Long-lasting red berries are important winter food for many birds including the thrush and small mammals.
Sorbus (Rowan or Mountain Ash)
Benefits for animals:
- Berries in autumn – these are quickly taken by blackbirds and small flocks of starlings and their recently fledged young. They’re also important for small mammals such as hedgehogs.
- 160 species of insect have been recorded feeding on this species – 14 of those are exclusive.
- Sweet-smelling flowers in the spring attract over 28 associated insect species.
- The Sorbus family is attractive to aphids and sawflies – important food for chicks.
Please contact email@example.com for any further information on any of the plants mentioned above, which are all currently available from the Nicholsons’ Plant Centre. Check in again next week for some more of Stephen’s selections.