Guidelines for the Selection of Biological Heritage Sites
6. Section 1: Habitat Guidelines
6.1 WOODLAND AND SCRUB
Wd1 Sites included on the Lancashire Inventory of Ancient Woodland which support semi-natural woodland vegetation.
Application
All sites listed in the Inventory (English Nature 1994a) should be included except for woods which have been felled and replanted with non-native species and have lost most of their ancient features.
Justification
The Inventory includes all woods over 2 hectares considered by English Nature on the basis of a desk study to be ancient in origin. As the irreplaceable remnants of the natural `climax vegetation of most of Lancashire, all such sites are considered an integral part of the Countys biological heritage. This also applies to sites which have been extensively modified but retain some of their ancient features, e.g. ground flora elements.
Wd2 Other semi-natural woodlands over 1 hectare where field evidence indicates that they are ancient in origin.
Application
Ancient semi-natural woodlands which are not included in the Inventory (see Wd1) can be included here. Woods smaller than 2 hectares are included only if evidence of ancient origin is particularly strong and/or they are especially good examples of particular semi-natural types.
Justification
A small number of ancient semi-natural woods over 2 hectares is missing from the Inventory (see Wd1). The 2 hectare minimum size qualification for inclusion in the Inventory is a national standard, whilst most of Lancashires ancient semi-natural woods are small by national standards. Consequently, there are a number of sites which merit inclusion in terms of habitat quality which are between 1 hectare and 2 hectares in extent.
Wd3 Other woodlands over 2 hectares which add significantly to the biodiversity of the Landscape Zone(1) in which the site occurs.
Application
Woodlands which are mostly of secondary origin but are considered to be important for biodiversity in terms of species or local genetic diversity may be included here. Such sites are generally restricted to areas which now support little or no ancient woodland, e.g. the Fylde (Amounderness).
Justification
Secondary woodland can be an important habitat for many more mobile wildlife species, particularly in areas or situations where ancient woodland is absent or rare. This guideline aims to identify the most important of such sites.
Wd4 Broadleaved woodlands over 2 hectares containing 5 or more trees per hectare estimated to be more than 200 years old.
Application
Woodlands included here may be ancient or mainly secondary and the broadleaved trees concerned may be native or non-native to the area.
Justification
Old and over-mature woodland trees are extremely valuable wildlife habitats. They provide internal spaces for nesting/roosting birds, bats or bees for example, and also habitat continuity needed by other species with very limited powers of dispersal and colonisation. They may also provide valuable evidence of the nature of past woodland management.
Wd5 (a) Areas of semi-natural woodland or scrub greater than 0.25 hectare referable to one of the following NVC(2) types:
W3 Salix pentandra - Carex rostrata woodland.
W17Quercus petraea - Betula pubescens - Dicranum majus woodland
Wd5 (b) Areas of semi-natural woodland or scrub greater than 0.5 hectare referable to the following NVC(2) types:
W2 Salix cinerea - Betula pubescens - Phragmites australis woodland
W4 Betula pubescens - Molinia caerulea woodland
W5 Alnus glutinosa - Carex paniculata woodland
W7 Alnus glutinosa - Fraxinus excelsior - Lysimachia nemorum woodland
Wd5 (c) Areas of semi-natural woodland or scrub greater than 1.0 hectare referable to the following NVC(2) types:
W1 Salix cinerea - Galium palustre woodland
W6 Alnus glutinosa - Urtica dioica woodland
W23 Ulex europaeus - Rubus fruticosus scrub
The NVC types shown are either rare woodland types which tend to occur in small
Application
This guideline should be applied to sites which do not satisfy guidelines Wd1, Wd2 or Wd3. Consideration may be given to the inclusion of stands of the above woodland types less than the areas shown where these occur in association with habitats which comply with other guidelines, and with which they may have a seral relationship. NVC types should be identified by a competent field surveyor familiar with NVC.
Justification
stands only, or are more frequent types stands of which are of nature conservation significance at the area thresholds shown, but which may occur isolated from other larger areas of semi-natural woodland. Some of these types are successional stages in the conversion of grassland (or other non-woodland habitats) to woodland. Management of such vegetation might be directed at arresting such a succession, encouraging it or reversing it to create habitat(s) of the greatest value to wildlife, depending on the geographical and ecological context of the site concerned.
(1) See Appendix 1.
(2) National Vegetation Calssification, published as Rodwell
(1991a).