7: Deadwood

What information does the survey provide and why does it matter?

The Native Woodland Survey of Scotland can estimate mean total volume per hectare (standing and fallen aggregated) for each type of woodland across a local authority area.

The biodiversity value of deadwood varies depending on size and tree species as well as whether it is fallen or standing, but overall volume is a reasonable indication of value across the whole of a region such as a local authority area.

Volume estimates at woodland level would have required much higher sampling intensity and were judged unacceptably expensive for the extra benefit they would have brought.

Deadwood is an important component of woodland ecosystems, which supports a range of specialist invertebrates, fungi, lichens and bryophytes as well as several birds and bats which use tree holes for nesting/roosting.

Dead wood and dying wood, and especially large dead trees, are typically under-represented in most Scottish woods compared to what might be expected to have developed in unmanaged semi-natural forests. More deadwood is often desirable to sustain populations of rare and threatened deadwood species in the long term.

We have limited baseline information on amounts of dead wood in Scottish woodlands. Data from the National Inventory of Woodland and Trees sampled in 1995-1999 estimated that mean volume was 4.4m3/ha (and was similar for native and non-native woods).

The Native Woodland Survey of Scotland can estimate mean volume per hectare for each type of woodland across a local authority area. Breakdown is also possible by size classes and fallen or standing but not by tree species. Volume estimates at woodland level would have required much higher sampling intensity and were judged unacceptably expensive.

The NWSS has also collected data on veteran trees (see structural diversity). Veteran trees support a range of the same species that use dead and dying wood, and will form a supply of large standing and fallen dead wood if left in situ. So veteran trees and dead wood information should be linked in management planning.

Policy relevance

Increasing dead wood volume is highly desirable to increase biodiversity value of both native and non-native woods to meet the aims of the Scottish Forestry Strategy.

How can the NWSS data be used?

Type of useNationalRegional/local authorityLandscape/site scale
Use regional/national mean volume of dead wood per hectare for each type of native woodland to set regional/national targets or as context to assess management objectives for sites Yes Yes Yes
Use dead wood and veteran tree data to target survey and management for particular dead wood species Yes Yes Yes