National Vegetation Classification (NVC)
The National Vegetation Classification (NVC) is one of the key common standards developed for the country nature conservation agencies. The original project aimed to produce a comprehensive classification and description of the plant communities of Britain, each systematically named and arranged and with standardised descriptions for each.
It was originally commissioned in 1975 by the Nature Conservancy Council (NCC) and was intended as a new classification, not an attempt to fit British plant communities into some existing scheme derived from elsewhere in Europe. The general approach adopted was phytosociological and, therefore, concentrated on the rigorous recording of floristic data. It did, nevertheless, try to avoid over-scrupulous selection of samples, rejection of awkward data and preoccupation with the hierarchical taxonomy of vegetation types.
- Use of the NVC
- What does the NVC cover?
- NVC Publications
- NVC types & floristic tables
- NVC survey data & distribution maps
- Review of coverage
- Additional resources
Use of the NVC
Since its publication between 1991 and 2000, the National Vegetation Classification (NVC) has been widely welcomed as providing a much-needed common language in which the character and value of the vegetation of Britain can be understood. It has been accepted as a core standard, not only by the nature conservation and countryside organisations, but also by forestry, agriculture and water agencies, local authorities, non-governmental organisations, major industries and universities.
The NVC in itself is not a monitoring tool, but is used to help furnish protocols for particular monitoring programmes and to develop a conceptual basis for understanding the purpose and practice of monitoring. The predictive capacity of the NVC means that it can also serve as a basis for developing management options for sites or landscapes and as a framework for restoration and design guidelines. Its popularity is evidenced by the sale of over 10,000 copies of the main volumes, published by Cambridge University Press.
Importantly, the NVC acts as the main terrestrial habitat classification for:
- the Guidelines for the Selection of Biological Sites of Special Scientific Interest
- UK Common Standards Monitoring Guidance
- the UK Interpretation of Annex I habitats listed under the EC Habitats Directive;
- detailed ecological site survey and assessments – it is used widely by the UK country nature conservation bodies (CNCBs) and many other organisations to produce inventories and maps of plant communities on designated or threatened sites.
Correspondences with other classifications
Correspondences have been identified between the communities and sub-communities of the NVC and types in other mainstream vegetation/habitat classification systems. These include:
- UK BAP Broad & Priority habitat types (based on the list of habitats produced prior to the Species and Habitats Review in 2008)
- Phase 1 Habitat Classification
- EU Habitats Directive Annex I
- EUNIS (European Union Nature Information System) Classification
- Vegetation communities of British lakes
A spreadsheet outlining these correspondences was produced in 2008.
What does the NVC cover?
The NVC is a detailed phytosociological classification, which assesses the full suite of vascular plant, bryophyte and macro-lichen species within a certain vegetation type. It is based on about 35,000 samples of vegetation. These cover nearly all natural, semi-natural and a number of major artificial vegetation communities in terrestrial, freshwater and maritime situations across Great Britain (but not Northern Ireland).
The NVC contrasts with broader-scale classifications, notably the Phase 1 Habitat Classification and the Biodiversity Action Plan (BAP) Broad Habitats. These do not break down broad habitat types into such detailed constituent parts as the NVC does. The NVC is, however, less comprehensive in coverage than the Phase 1 Habitat Classification, because it does not encompass habitats which lack vascular plant growth (such as many aquatic and rock habitats), and not all artificial habitats are covered.
As the NVC is based solely on plant species composition, its application is limited in certain habitat types where floristics are not the best tool for their definition. For example, the NVC is less appropriate to the dynamic vegetation of aquatic systems and an alternative classification has been applied to the selection of freshwater Sites of Special Scientific Interest.
Structural variation in vegetation is not well represented in the NVC, limiting its value as a habitat classification for invertebrates and other fauna. Other specialised habitats, such as river shingle, may have biodiversity importance but no vegetation: as such they are not covered by the NVC.
NVC volumes – British Plant Communities
The NVC was published by Cambridge University Press in a five-volume series entitled British Plant Communities, edited by John Rodwell. The final volume includes a phytosociological conspectus of British Plant Communities, placing the NVC in a European framework.
- Rodwell, J.S. (ed.) 1991. British Plant Communities. Volume 1. Woodlands and scrub. Cambridge University Press.
- Rodwell, J.S. (ed.) 1991. British Plant Communities. Volume 2. Mires and heaths. Cambridge University Press.
- Rodwell, J. S. (ed.) 1992. British Plant Communities. Volume 3. Grassland and montane communities. Cambridge University Press.
- Rodwell, J.S. (ed.) 1995. British Plant Communities. Volume 4. Aquatic communities, swamps and tall-herb fens. Cambridge University Press.
- Rodwell, J.S. (ed.) 2000. British plant communities. Volume 5. Maritime communities and vegetation of open habitats. Cambridge University Press.
NVC Handbook, field guides and summary descriptions
In addition to the main volumes, a series of other publications and reports are available:
- The NVC Users' Handbook (2006). An introduction to the NVC, its application, and advice on carrying out and analysing an NVC site survey.
- An Illustrated Guide to British Upland Vegetation (2004). A major work that brings together and describes all NVC communities found in the uplands. It includes updated distribution maps for the communities involved.
- The NVC Field Guide to Woodland (revised 2004) (includes updated distribution maps for woodland communities). The NVC woodland classification is based on 2,648 samples from ancient and recent woods throughout Britain (Rodwell 1991). This is the biggest dataset yet analysed for the production of a woodland classification in Britain (the Stand Type system, for example, was based on about 800 samples (Peterken 1981)). Apart from the sheet numbers of samples, the geographic and ecological spread of sampling makes it the classification most representative of the range of British woodland. The relationships between the NVC and other woodland classifications are shown in Appendix 1.
- Summary of NVC Woodland Descriptions (1992) (largely superseded by the NVC Field Guide to Woodland). This provides straightforward descriptions of the 18 woodland types identified by the NVC, and keys to their sub-communities. A valuable complement to the NVC, especially for use in the field.
- NVC Field Guide to Mires and Heaths (2002). This volume gives a detailed account of 38 mire communities and 22 heath communities in the UK, providing information on their composition, structure and distribution. From these descriptions, it also relates their similarity and environmental status to other types of vegetation categories, both in Britain and on the continent.
- Summary descriptions of NVC Grassland and Montane Communities (1998) (note a downloadable version of this document is not available). An aide-memoir for field workers and others that combines a series of keys and summary descriptions covering all mesotrophic, calcicolous and calcifugous grassland types within Volume 3 of the National Vegetation Classification.
NVC types & floristic tables
The NVC comprises 286 community types subdivided amongst 12 major types of vegetation. These are arranged in the published NVC volumes as shown (codes for types are given in brackets)
|NVC volume||Major vegetation Type|
|NVC Volume 1||Woodlands and scrub ((W1–W25)|
|NVC Volume 2||
|NVC Volume 3||
Mesotrophic grasslands (MG1–MG13)
Calcifugous grasslands and montane communities (U1–U21)
|NVC Volume 4||
Aquatic communities (A1–A24)
Swamps and tall-herb fens (S1–S28)
|NVC Volume 5||
Shingle, strandline and sand-dune communities (SD1–SD19)
Salt-marsh communities (SM1–SM28)
Maritime cliff communities (MC1–MC12)
Vegetation of open habitats (OV1–OV42)
Many, but not all, of the NVC communities are broken down further into sub-communities, which total 578 in all. A very small number of especially bulky and complex communities have a third level of sub-division, into variants. Considering the lowest sub-division of each type, except variants, the NVC comprises 681 units.
A spreadsheet containing the codes and names of all the NVC communities and sub-communities accompanies the Users' Handbook. This includes information on species used to define particular communities and sub-communities that have changed their scientific name/status since the publication of the original NVC volumes.
Full descriptions of each of the NVC communities and sub-communities are contained within the published NVC volumes. They include summary information on the general species composition and appearance (physiognomy), the associated habitat, and zonation and successional characteristics. In addition, a detailed floristic table is available, along with information on the geographic distribution. Brief descriptions (and some other information) are available for certain NVC communities/sub-communities:
- Mires and heaths – NVC field guide to mires and heaths
- Uplands – An Illustrated Guide to British Upland Vegetation
- Woodland – NVC field guide to woodland (includes updated distribution maps for woodland communities)
NVC floristic tables
Each community/sub-community within the NVC is uniquely defined by a particular combination of frequency and abundance values for the species found in the samples grouped within it. This information is summarised in a standardised tabular format (i.e. a 'floristic table').
Each floristic table includes all of the vascular plants, bryophytes and macro-lichens that occur within the type with a frequency of 5% or more in any one of the sub-communities (or for vegetation types with no sub-communities within the community as a whole). The species are arranged in blocks to indicate their pattern of occurrence through the community, as explained in the NVC Users' Handbook and main NVC Volumes.
A spreadsheet containing much of the information in the NVC floristic tables accompanies the Users' Handbook.
NVC survey data & distribution maps
NVC survey data
The published volumes of the NVC are based on a total of about 35,000 samples or relevés. In most cases these comprise a list of species and their abundances from a single square quadrat, together with information on the locality, soil, etc. For woodland stands, however, a sample summarises data from three nested quadrats, each covering a separate layer (i.e. field layer, tall field layer, canopy and shrub layer).
Since the time of original publication, many thousands more NVC samples have been made. Some have associated site maps that show the extent of particular NVC communities/sub-communities. The country nature conservation bodies and others have significant data holdings coded using the NVC. Some of the more extensive NVC surveys have been collated or summarised, for example:
- Sand Dune Vegetation Survey of Great Britain (see Dargie 1993, Dargie 1995, Dargie 2000, Radley 1994);
- Coastal Vegetated Shingle Structures of Great Britain (see Sneddon and Randall 1993);
- NVC Review of Scottish Grassland Surveys (see Cooper and MacKintosh 1996);
- Review/experience of woodland NVC data (see Hall 1997, Goldberg 2003);
- Lowland Grassland Survey of Wales (see Stevens et al. 2007);
- Lowland Heathland in Wales (see Sherry 2007).
Although some of this data has been encoded in various types of database or spreadsheet software, much has not, and NVC information remains widely dispersed in numerous locations that are not linked electronically. There is no centralised database of all NVC samples or surveys undertaken.
Distribution maps of NVC types
A collection of Excel-based mapping tools is available on JNCC's Resource Hub, which show the distribution of NVC types in Britain, dating back to around 2008 or earlier. There are four resources, covering the following NVC types:
- Upland (as published in An Illustrated Guide to British Upland Vegetation)
- Lowland Grassland
- Lowland Heathland (in Wales).
Review of coverage
A review of the coverage of the NVC was commissioned in 1998 (see JNCC Report 302). This produced information on the coverage of NVC, identified both known and likely gaps in the plant community descriptions, partly by comparing the NVC with European phytosociological classification systems, and placed these potential new types into the phytosociological scheme of the NVC. A number of further communities were identified that have still to be described in full within the NVC. These include, amongst others:
- communities in aquatic situations
- various weedy/rank/fringe communities
- vegetation of shingle and strandlines
- mud-flat and lagoon assemblages
- certain grassland, heath and montane types
- communities of rock crevices and scree.
A compilation of proposed additions and revisions to vegetation types in the NVC (JNCC Report 448) was prepared by JNCC in 2011. This was limited to known information that could be accessed fairly readily. The proposals were numerous and covered a wide range of vegetation types. Although some of them appeared relatively straight-forward and uncontroversial, others were much more complex. No detailed appraisal or recommendation was given regarding validity or acceptance into the published NVC scheme.
- Dargie, T.C.D. 1993. Sand dune vegetation survey of Great Britain, a national inventory Part 2: Scotland. Joint Nature Conservation Committee.
- Dargie, T.C.D. 1995. Sand dune vegetation survey of Great Britain, a national inventory Part 3: Wales. Joint Nature Conservation Committee.
- Dargie, T.C.D. 2000. Sand Dune Vegetation Survey of Scotland: National Report. Scottish Natural Heritage, Battleby.
- Goldberg, E. (ed.) 2003. National Vegetation Classification – ten years' experience using the woodland section. Joint Nature Conservation Committee Report No. 335.
- Hall, J.E. 1997. An analysis of National Vegetation Classification survey data. Joint Nature Conservation Committee. Report No. 272.
- Kirby, K.J., Saunders, G.R. & Whitbread, A.M. 1991. The National Vegetation Classification in nature conservation surveys. British Wildlife, 3, 70–80.
- Mountford, E. 2011. A compilation of proposed additions and revisions to vegetation types in the National Vegetation Classification. Joint Nature Conservation Committee Report No. 448.
- Radley, G. 1994. Sand dune vegetation survey of Great Britain, a national inventory Part 1: England. Joint Nature Conservation Committee.
- Rodwell, J.S. 1997. The NVC and monitoring. Countryside Council for Wales, Contract Science Report, No 200.
- Rodwell, J.S., Dring, J.C., Averis, A.B.G., Proctor, M.C.F., Malloch, A.J.C., Schaminée, J.N.J. & Dargie, T.C.D. 2000. Review of coverage of the National Vegetation Classification. Joint Nature Conservation Committee Report No. 302.
- Rodwell, J. & Dring, J. 2001. European significance of British woodland types. English Nature Research Reports No. 460.
- Rodwell, J.S., Morgan, V., Jefferson, R.G. & Moss, D. 2007. The European context of British Lowland Grassland. Joint Nature Conservation Committee Report No. 394.
- Sherry, J. 2007. Lowland heathland in Wales - a review and assessment of National Vegetation Classification survey data 1993–2002. Countryside Council for Wales Staff Science Report, No 07/3/1.
- Sneddon, P. & Randall, R.E. 1993. Coastal vegetated shingle structures of Great Britain. Main report. Joint Nature Conservation Committee.
- Stevens, D., Blackstock, T., Smith, S. & Bosanquet, S. 2007. Lowland grassland survey of Wales. British Wildlife, 18(5), 314–323.
- Wheeler, B.D., Shaw, S., & Tanner, K. 2009. A wetland framework for impact assessment at statutory sites in England and Wales. Environment Agency, Bristol.