If you are having to remove Ash trees due to Ash dieback, then it is important to consider the replacement tree species to aid with future restocking. Diversity of replacement tree species is key as Ash as a species provided a diverse habitat for a wide range of species.
The aim is to ensure a resilient future landscape, one which can cope with current and future threats while remaining attractive, functional and rich in wildlife.There is no one tree species that can replace Ash. Aspen, Sycamore and Elm are the closest match. It is strongly recommended to plant a rich diversity of trees as this will benefit the ecological void that loss of Ash will create. It will also provide a far more resilient landscape in the face of the many tree diseases that threaten our landscape and trees.
Factors to consider when selecting replacement species
The following factors will be taken into consideration with any proposed replacement tree species and will include:
- Soil – select trees that will grow well in the soil in which is to be planted. Acidity, drainage and the type of soil will all have a bearing. Some tree species are more specific than others as to their requirements.
- Local distinctiveness – Try to link with what species grow naturally in the area already. Native species are usually best for wildlife and ‘fit in’ with the landscape character and are normally preferable to ornamental species. This links in with selecting species appropriate for designations like SSSI sites, AONB, SINCs, Ancient woodland and LNR’s.
- Climate – Ensuring that any species selected will be able to survive the current climatic conditions for the site as well as aiming to provide future resilient tree species for potentially warmer climatic conditions focusing on drought tolerant trees or species with water stress adaptations
- Management – Ensuring that any replacement species selected are able to be managed in line with current management approaches for the location, for example trees that can be pruned or managed in certain ways.
- Available space – Ensure that the tree or trees are able to reach full life expectancy size without causing future conflict with buildings, shading, overhanging roads and footpaths etc. The mature size of the tree species can be calculated to ensure that any species planted has sufficient space to develop into maturity without conflict where possible.
- Benefits – as well as having obvious ornamental attributes, trees provide shelter, reduce temperature extremes and produce oxygen. So species replacement choice should aid to enhance or provide additional benefits in the location for the replacement species.
Sourcing replacement trees
All trees should be sourced from reputable tree nurseries in the UK and proof of provenance should be one of the requirements of purchase as part of biosecurity measures.
All trees should be selected at source from nurseries prior to ordering and all orders should be checked on site at point of delivery prior to planting. If trees fail to meet the criteria or standard they should be rejected at point of delivery and replacements ordered.
All trees sourced should be required to conform to industry nursery stock standards and general guidelines below:
- Ensure that the tree has a single, straight undamaged leading shoot or a balanced and well developed branching head according to the species or cultivar.
- Ensure there are no damaged branches or areas of bark and the tree is free from obvious pests and diseases.
- Bare rooted trees should have a balanced and fibrous root system which has been (and should be) protected from drying out at all times.
- Ensure following biosecurity guidelines for buying trees in the UK, grown in the UK to avoid the potential for new pests and diseases being imported
First choice for Ash species replacements
In light of the mature size of Ash trees as a species where the site allows the first list of species to be reviewed for potential replacements should be the large tree species. If more than one replacement tree is to be planted then it may be worth considering a selection of species across all three size classes and of both native and ornamental origin if the site allows for this.
Large native trees in the UK (15-30m)
- Sycamore (Acer pseudoplatanus)
- Hornbeam (Carpinus betulus)
- Beech (Fagus sylvatica)
- Black Poplar (Populus nigra)
- Aspen (Populus tremula)
- English oak (Quercus robur)
- Sessile Oak (Quercus petraea)
- White Willow (Salix alba)
- Common Lime (Tilia x europaea)
- Large leafed Lime (Tilia platyphyllos)
- Small leaved Lime (Tilia cordata)
- Smooth leaved English Elm (Ulmus minor var minor)
Large ornamental trees
- Silver Fir (Abies alba)
- Caucasian Fir (Abies nordmanniana)
- Silver maple (Acer saccharinum)
- Sugar maple (Acer saccharum)
- Horse Chestnut (Aesculus hippodastanum)
- Indian Horse Chestnut (Aesculus indica)
- Shagbark hickory (Carya ovata)
- Sweet Chestnut (Castinea sativa)
- Indian Bean Tree (Catalpa bignioides)
- Japanese Cedar (Cryptomeria japonica)
- Handkerchief tree / Dove tree (Davidia involucrata)
- Maidenhair tree (Ginkgo biloba)
- Black walnut (Juglans nigra)
- European larch (Larix decidua)
- Tulip tree (Liriodendron tulipifera)
- Dawn Redwood (Metasequoia glyptostroboides)
- Hop Hornbeam (Ostyra carpinifolia)
- Fox glove tree (Paulownia tomentosa)
- London plane (Platanus x hispanica)
- Oriental plane (Platanus orientalis)
- Holm Oak (Quercus ilex)
- Pin Oak (Quercus palustris)
- Red Oak (Quercus rubra)
- Giant Redwood (Sequoiadendron giganteum)
- Coastal Redwood (Sequoia sempervirens)
- Swamp cypress (Taxodium distichum)
- Silver Lime (Tilia tomentosa)
- Resistant Elms (Ulmus new horizon/ Ulmus lobel)
Second choice for Ash species replacements
If the site or location cannot accommodate a large tree at maturity then the list of medium size trees should be reviewed for the selection of a suitable replacement tree species to be planted. It may be possible to even consider two or more medium size trees as opposed to one larger species.
Medium size Native to the UK trees (8m-18m)
- Field Maple (Acer campestre)
- Alder (Alnus glutinosa)
- Silver Birch (Betula pendula)
- Downy Birch (Betula pubescens)
- Alder Buckthorn (Frangula alnus)
- Common Juniper (Juniperus communis)
- Scots Pine (Pinus sylvestris)
- Wild Cherry (Prunus avium)
- Bird Cherry (Prunus padus)
- Plymouth Pear (Pyrus cordata)
- Grey Willow (Salix cinerea subsp. oleifolia)
- Crack Willow (Salix fragilis)
- Bay Willow (Salix pentandra)
- Whitebeam (Sorbus aria)
- Rowan (Sorbus aucuparia)
- Wild service tree (Sorbus torminalis)
- Yew (Taxus baccata)
- Wych Elm (Ulmus glabra)
Ornamental medium size trees
- Fraser Fir (Abies Fraserii)
- Trident maple (Acer buergerianum)
- Amur maple (Acer ginnala)
- Lobel’s Maple (Acer lobelia)
- Box Elder (Acer negundo)
- Norway Maple (Acer platanoides)
- Purple Norway Maple variety (Acer platanoides ‘Crimson Sentry’)
- Red maple (Acer rubrum)
- Sweet Buckeye (Aesculus flava)
- Italian Alder (Alnus cordata)
- White Himalayan Birch (Betula utilis var jacquemontii)
- Katsura tree (Cercidiphyllum japonicum)
- Turkish Hazel (Corylus colourna)
- Common Walnut (Juglans regia)
- Sweet Gum (Liquidamber styraciflua)
- Persian Ironwood (Parrotia persica)
- Mitchell Whitebeam (Sorbus thibetica John Mitchell)
- Bastard Service tree (Sorbus thuringiaca ‘Fastigiata’)
- Lime cultivar (Tilia ‘Harold Hillier’)
- Caucasian Lime (Tilia x euchlora)
- Lime (Tilila henryana)
- Mongolian Lime (Tilia mongolica)
- Thuja (Thujopsis dolabrata)
- Wollemi Pine (Wollemia nobilis)
- Japanese Elm (Zelkova serrata)
Final choice for Ash species replacements
Where the location is so restrictive then the small tree species replacement list should be considered and an appropriate species selected from the example list.
Small native UK tree species (up to 8m)
- Common Box (Buxus sempervirens)
- Dogwood (Cornus sanguinea)
- Hazel (Corylus avellana)
- Midland Hawthorn (Crataegus laevigata)
- Hawthorn (Crataegus monogyna)
- Spindle (Euonymus europaea)
- Holly (Ilex aquifolium)
- Privet (Ligustrum vulgare)
- Crab apple (Malus sylvestris)
- Blackthorn (Prunus spinosa)
- Purging Buckthorn (Rhamnus cathartica)
- Goat Willow (Salix caprea)
- Osier Willow (Salix viminalis)
- Elder (Sambucus nigra)
- Guelder rose (Viburnum opulus)
Ornamental small trees
- Korean Fir (Abies koreana)
- Silver Wattle (Acacia dealbata)
- Paper Bark maple (Acer griseum)
- Japanese maple (Acer palmatum)
- Cut leaved Alder (Alnus glutinosa ‘Imperialis’);
- Himalayan Birch (Betula utilis ‘Silver Shadow’)
- Judas tree (Cercis siliquastrum)
- Pillar Apple (Malus tschonoskii)
- Sargent’s Cherry (Prunus sargentii ‘Rancho’)
- Chanticleer Pear (Pyrus calleryana ‘Chanticleer’)
- Golden Robinia (Robinia pseudoacacia ‘Frisia’)
- Fern leaved Rowan (Sorbus aucuparia ‘Asplenifolia’)
- Japanese Rowan (Sorbus commixta)