Managing trees in the landscape

Method/Notes Benefits for biodiversity and issues to watch out for
  • The management of individual veteran trees is often complex, each tree may need to be treated as an individual case. Allowing retrenchment to occur is key to the tree surviving into senescence.
  • Maintain mature and veteran trees, maximising diversity of species, shape, and aspect. As a last resort, tree surgery may be required to lengthen life.
  • Control ivy where significant lichens and mosses are present, ideally using grazing animals.
  • Existing veteran trees should be retained and 'future veterans' and 'old growth' features encouraged by retaining specific trees to mature and decline naturally.
  • Felling should not normally be considered an option for veteran trees but remedial action of some kind may be warranted where an intolerable risk of harm to people has been identified. Lichen rich woodlands mainly require management at the stand not tree level, ensuring openness and tree succession. Individual tree management rarely practical in this situation.
image: Nigel Symes, RSPB

Veteran trees support a wide range of species, many of which are slow colonisers or require specific niches in old trees. These include many fungi, lichens and rare invertebrates, as well as bats and birds. Deadwood on veteran trees is particularly important. Veteran trees can also provide links to other habitats, enhancing connectivity and providing wider opportunities for biodiversity.

Retrenchmant is when maturing trees such as oak, yew, sweet chestnut, ash and others lose upper crown branches and change the root and shoot ratio by development of a smaller inner and lower crown, during the later stage of the life of the tree. This maintains a functioning system in the tree for the movement of water and sugars around the tree with reduced crown volume to photosynthesise efficiently. It can prolong the life of the tree after post maturity into senescence significantly (up to 300 years).

Factors allowing this to occur are:

  • Low live branch structure available to replace a failing upper crown.
  • Epicormic bud development on the stem
  • Adequate light and distance from adjacent trees and vegetation.
  • Stems free of undergrowth i.e. ivy, bramble.
Method/Notes Benefits for biodiversity and issues to watch out for
  • Ensure the long term presence of decaying wood habitat.
  • Manage pasture woodland as semi-natural woodland by patchy natural regeneration occurring through controlled grazing
  • In larger lichen rich sites, rely on natural process, not tree surgery to create suitable trees.
  • Consider pollarding young trees or planting/encouraging young trees in parklands or very open damaged woodlands
  • Identify future veteran trees and conserve in small or intensively managed sites.
  • Remove excessive recent woodland and scrub caused by removal of grazing or conifers where necessary, but maintain scrub nearby as it is a crucial nectar/food source for many decaying wood invertebrates and patches of young trees as future old growth stands.
  • Consider major tree surgery to increase the life span of the veterans, or even veteranisation of younger trees (where not lichen rich) in sites with large generation gaps.
  • Manage the open space and open woodland within which the trees are growing. Grazing animals are likely to be essential in woodlands, mowing will generally only be practical in non-woodland situations. Animal dung contributes to invertebrate and fungal diversity.
image: Nigel Symes, RSPB

Provides specialized and varied micro habitats for a wide variety of species, many of which can only be found in this habitat, particularly insects, lichens and fungi which depend on dead and decaying wood. Also provides good nesting habitat and connectivity for birds such as lesser spotted woodpeckers, and roosting sites for some bats.

Method/Notes Benefits for biodiversity and issues to watch out for
  • Woodland isolation limits the ability of many species to disperse, including larger species such as birds and bats.
  • Improving connectivity between woods includes enhancing hedgerows, encouraging scrub, and creating new woodland patches.
image: Andy Hay (rspb-images.com)

Connecting habitats at a landscape scale promotes maximum benefit and resilience for biodiversity by allowing migration and colonisation as well as providing the greatest variety of food/nesting opportunities. Connection between woodlands is particularly important for species which do not easily disperse across open spaces, such as willow tits. New woodland should be carefully sited to not damage/remove other valuable habitats such as semi-natural grassland or heathland.

Method/Notes Benefits for biodiversity and issues to watch out for
  • Providing connecting habitat between established woodland; pioneer woodland is important for a number of species.
  • Natural regeneration by colonisation is generally preferable, but planting of suitable native species - using the National Vegetation Classification as a guide - may be necessary.
image: Woodland Trust

An opportunity to provide habitats and niches for woodland species into the future, and to buffer and link existing woodland. New woodland should be carefully sited to not damage/remove other valuable habitats such as semi-natural grassland or heathland.

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