2: Degree of semi-naturalness of native woods

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

Native woods are often classified as semi-natural or planted. Semi-natural woods are, strictly speaking, those which have arisen from natural regeneration from parent trees. They are generally considered to be of higher value for nature conservation than planted woods, because they should have a more natural structure and composition and a higher value for genetic conservation than planted woods. Some of them may even be direct descendants/relics of original woodland cover. For guidance on ancient semi-natural woods (ASNW), see Ancient Woodland Information.

In most cases, however, it is not possible to be definitive about whether a wood has regenerated naturally, because we do not have sufficient historical information.

The survey therefore assessed semi-naturalness in terms of current structure and composition of the trees and shrubs, i.e. to what extent did each area of native woodland surveyed appear to have been planted or not?

This semi-naturalness measure is expressed as a percentage of the site: it is a continuum since planted native woods can develop a more semi-natural structure and appearance through time. This can occur both though the effects of natural disturbance events such as storms and as a result of management that promotes natural regeneration of native species and the development of an irregular structure. Planted new native woods are also often designed to mimic the structure and composition of semi-natural woodlands.

Woods with a high semi-naturalness percentage value in the survey are likely to be naturally regenerated, at least in part, and/or may have a more diverse range of niches and species. In these woods a presumption in favour of encouraging natural regeneration should normally be made, except where there is other evidence of previous planting.

Policy relevance

Semi-natural native woods are recognised as more important generally for nature conservation than planted native woods, especially if they are on ancient woodland sites. Guidance on management of semi-natural woods is set out in a series of Forestry Practice Guides (The management of semi-natural woodlands Numbers 3-8. Forestry Practice Guides, Forestry Commission,1994.) Links to these documents are provided on the right hand side of this page.

How might the NWSS data be used?

Type of useNationalRegional / local authorityLandscape / site scale
Areas of mainly semi-natural or planted native woods; use for strategic planning or targeting incentives for management Yes Yes Yes