There are many different classification systems within the UK the first notable one being Tansley (1939) who used dominant tree species to classify woodlands, however it is not always easy to determine the dominant species in mixed woodlands and much of the UK was missing. This was later improved by Peterken (1981 and 1993) who used the basis of Tansleys’ system, but concentrated more on the management and stand mixes, coming up with 89 ‘semi-natural ancient woodland’ stand types and sub- types (Peterken 1993). This was replaced by National Vegetation Classification (NVC) in 1991 which rather than just looking at the main stands incorporates all the woodland layers classifying them into communities. The NVC was commissioned by the Nature Conservancy Council in 1975 and divides woodland and scrub into 73 communities and sub-communities (Hall et al 2001). This system was developed to try and make classifications in the UK similar to those being used in Europe as well as to update the Tansley classification system. The NCV is more in-depth than both Tansley and Peterkins classifications as it covers the whole of the UK systematically (Rodwell 1991). The forestry commission have also come up with a classification system, this is mainly targeted at foresters, using climatic and soil property factors that influence tree growth to determine favourable woodland/ tree types for individual sites (Pyatt et al 2001).
In 1992 the United Nations conference’ Earth Summit’ met in Rio Janeiro and came up with Agenda 21 on the environment and sustainable development, climate change and biological diversity. A result of this was the European Union Habitats and Species Directive and the UK Biodiversity Action Plan, these require that habitats and species which are threatened or likely to become threatened are protected and preserved. Habitats that are listed in Annex 1 of the Habitats and Species Directive have to be classified in all member states. The habitats listed in Annex 1 are rather broad as they are for all the EU countries, there is an interpretation manual which tries to help determine what is required for each habitat classification however the descriptions are in many instances very misleading (Hall & Kirby 1998; Rodwell & Dring 2001). The UK has classified its primary woodland types and also those which are important to the UK though may not fully be classified as one of the Annex 1 forest Habitats. There have been efforts to make comparisons with the other classification systems for woodland in the UK. I hope to briefly cover the methods used for the Peterken, NVC, Ecological Site Classification and the Habitats Directive and there usefulness for conservation.
Peterken Stand Types:
Peterken 1993 Stand Types: These are first split into 12 groups, some of which may be identified by one tree species, others by more than one. Groups 7-11 are classed using five species which rarely occur together and have well-defined geological ranges. The mixed deciduous groups (1-6 and 12) are split successively with the presence of species present in the woodland type increasing (see Table 1).These groups where then split into stand types depending on the soil, drainage, topography and geology as well as the correlation of corresponding dominant, field layer species associated with each.
Table 1: Peterken Main Stand Types, above the line shows the groups with there associated dominant species opposite, under the line shows the mixed woodlands and the species found within them which accumulate as you go down the list. (Adapted from Peterken 2003).
GroupStand typeindicator species
Group 7AlderwoodsAlnus glutinosa
Group 8BeechwoodsFagus sylvatica
Group 9Hornbeam woodsCarpinus betulus
Group 10Suckering elm woodsUlmus carpinifolia, Ulmus procera Group 11PinewoodsPinus sylvestris
Group 1Ash-wych elm woodsUlmus glabra
Group 4Ash-limewoodsTilia cordata, Ulmus...