Species for Woodland Planting
When a woodland is planted the choice of species will be critical to the future of that wood. Certain species of tree may be removed in the future but (apart from some replacements the year after planting) further tree species cannot easily be added to the woodland. So always plant the widest range of trees and shrubs that are suitable for the site, this will allow the greatest number of options open for future management.
An old woodland site would have a particular range of tree species that reflects its past history and management. Often this means that they have quite a narrow range of species, but their value lies in their history and it would be unwise to lose this connection to the past by adding extra species to an old woodland site. By contrast, a new woodland is a clean slate and an opportunity to design a varied and rich woodland ecosystem.
A woodland is not just about tall trees, there are two other important elements that must be incorporated into the design stage of any woodland planting scheme. These are the understorey and the woodland edge.
The leaves of the understorey trees soak up the light that penetrates through from the canopy above. This keeps the trunks of the canopy trees in the shade making them grow tall and straight. The understorey is a sheltered woodland habitat with its own ecosystem. Many bird species spend their time in the understorey of a woodland, seldom venturing into the canopy above. A good percentage of understorey trees will help to shade out weeds in the new woodland so that by year 20 or so the woodland floor is clear and ready for establishing a woodland flora. I would recommend 40% understorey trees and 60% canopy trees.
Woodland edge species of trees and shrubs should be planted as a band about 5m wide (2 rows at 2.5m spacing) around all new woodlands. Because they are growing in full sunlight they will have an abundance of flowers and fruits, making them excellent for wildlife. Shrubs provide nesting sites for woodland birds and shelter the interior of the wood from uncomfortable winds. On larger planting sites the woodland edge trees and shrubs can be planted along ride sides deep into the heart of a wood.
Canopy trees. I always start with oak, pedunculate oak on neutral soils and sessile oak on acid soils.
At present ash cannot be planted due to the disease known as Chalara, but you may find that it seeds naturally if there are parent trees about.
Lime, smooth-leaved elm, hornbeam, Norway maple and sycamore make fine trees in a woodland.
Alder, aspen and birch are pioneer species. They are fast growing but will need to be thinned out at a later stage to allow other trees to fully develop.
Wild cherry, wild pear and wild service can all make large trees in a woodland and are particularly prized for their timber value.
Beech grows well in the right soils but is slow and can struggle when planted in a mixture of other species.
Sweet chestnut grows well on lighter soils.
Some North American trees such as red oak and black walnut grow well in UK conditions, but you should always think of a positive reason for choosing each species. A tree might be chosen because it produces valuable timber or it fills a particular ecological niche, or even because it looks particularly beautiful at a certain time of year. Don’t choose a tree simply because it will grow well.
Understorey trees. These should be planted throughout the wood to provide the benefits described above. Trees should include crab apple, wych elm, midland (or woodland) hawthorn, hornbeam, field maple, hazel, yew and, on lighter soils, rowan and holly
Woodland edge. This is where the choice is widest. Shrubs such as guelder rose, dogwood, spindle, hazel, and wild privet will provide flowers, berries and autumn colour. Why not take the opportunity to plant some fruiting cherries and plums along the woodland edge where they will be accessible to pick? If you don’t pick them, then all the more for the wildlife.