Ancient & semi natural

Although little, if any, woodland in Britain has any direct link now with the primeval “wildwood”, some is classified as “Ancient and Semi-Natural” and management restrictions may exist for these and other sites of special conservation value.

Ancient Semi-Natural Woodlands are a vital part of our heritage. They provide a range of habitats which support a wide diversity of plants and animals. Many woodland species depend entirely for their survival on the continued existence of these habitats. Ancient semi-natural woodlands – known as ASNWs – are a prominent feature in many landscapes and are a significant economic and historical resource. They are all that remain of the original forest which once covered most of Britain yet now occupy only 1% of the land surface.

Ancient Woods – are sites which have been wooded continuously for several hundred years and at least since the time when the first reliable maps were made. In England and Wales, ancient woods are those known to have been present by around 1600AD. In Scotland, they are those which were there before 1750 when their first national survey was done.

Some ancient woodlands may be remnants of our prehistoric or primary woods; others grew up as secondary woodland on ground cleared sometime in the past.

Although an ancient woodland might be over 400 years old, that does not mean to say that the trees present are all as old as that. Many ancient woods have been cut down and re-grown or replanted several times in recent centuries. During the 20th century, some were converted from native species to plantations of introduced trees. Where realistic, de-coniferisation is being encouraged and the conifers are being felled.

Semi-natural woods
© J. Jackson

Semi-Natural Woods – are stands composed mainly of locally native trees and shrub species which have not been planted.

“Ancient” and “Semi-Natural” are sometimes employed as synonyms but that is not quite correct. Ancientness refers to the site as woodland whereas naturalness refers to what is growing on that particular site.

ASNWs contain many different classes of woodland. Some are very ancient indeed but others originated in historically recent times. Some are more natural than others and of course border-line cases exist. However, all these divisions are rather arbitrary and man-made distinctions.

Because of their combination of naturalness and a long continuous history, ASNWs are often richer in wildlife (biodiversity) and support more rare habitats and species than more recent or less natural ones.

ASNWs are largely composed of trees and shrubs that are native to the site. They have developed from seedlings or stump re-growth through successive generations from the original trees in the wood which were self-sown. Those include:

  • primary woods on sites that have always been wooded
  • secondary woods which have colonised bare ground within historical times

Semi-natural woods, especially the oldest or “ancient” ones are the nearest we have to truly natural woodlands. They are very valuable wildlife habitats and an important part of our cultural heritage. There are about 537,000 hectares of ASNW in the UK – or around 19% of all woodland. Of that, 58% has not been modified much over the past 400 years.

The rest is termed “planted ancient woodland sites” or PAWS where other species – often conifers – were introduced to replace or modify the original woodland but it has remained tree covered throughout.

As a result of concern over the large losses of semi-natural woodland that have occurred since 1945, the Forestry Commission introduced new policies in 1985-89 aimed at conserving the remaining areas of semi-natural woodland, and of broadleaved woodland more generally, and extending them where appropriate.

More: The former Nature Conservancy Council carried out an inventory of ancient and semi-natural woodland and drew up maps. Those are held by what is now English Nature, the Countryside Commission for Wales and Scottish Natural Heritage and by the local Forestry Commission offices.

FC Bulletin 112. “Creating New Native Woodlands”. J.S. Rodwell & G.S.
Patterson. 1994. HMSO. J.S. Rodwell (Ed.) “British Plant Communities” Vol. 1; “Woodlands Scrub”. 1991. Cambridge University Press. “Woodland Conservation & Management”. 1993. G. Peterken. Chapman & Hall.

FC Practice Guide 14. Restoration of native woodland on ancient woodland sites. J.W. Humphrey. 2003.