6: Structural diversity

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

The distribution of cover in all the structural stages is important in affecting biodiversity, scenic and recreational potential and wood production capacity, now and in future.

High structural diversity normally means higher diversity of niches and associated species. Different priority woodland types tend to have characteristic structures. These are partly natural, related for example to typical disturbance patterns and to the degree of shade tolerance of the major tree species; and partly the result of past management practices. (See Practice Guides to the management of semi-natural woodland on the right hand side of this page).

Native pinewoods and upland birchwoods are typically relatively extensive and simple in structure with one or two age classes over most of the site. Lowland mixed deciduous woodland or upland mixed ashwoods are more fine-grained types which usually have smaller stands of trees and patches of regeneration.

The presence and extent of regeneration, which includes both visible regeneration (VR) and established regeneration (ER), is important to the sustainability of the woodland. A wood which is dominated by mature or veteran layers with no regeneration may be at risk and may need intervention to sustain it for the long term.

Veteran trees are usually of high biodiversity value, and each tree species has different potential communities of lichens, bryophytes, fungi and invertebrates.

Policy relevance

The Biodiversity value of woodlands is linked to diversity of structure, and so are amenity and recreational values.

How can the NWSS data be used?

Type of useNationalRegional/local authorityLandscape /site scale
Assess whether to manipulate structure e.g. by promoting regeneration or planting, thinning or respacing etc. Yes Yes Yes
Locate areas of selected structural stages which are used as habitat for particular species. Yes Yes Yes