What does the NVC cover?

 
 

Distribution of samples upon which the NVC is basedCurrent Coverage of the NVC

 
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, the distribution of which is shown in the map left. 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 Phase 1, 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.
 
 

Review of the coverage and proposed changes to the NVC

 
Strandline vegetation community growing on shingleA review of the coverage of the NVC was commissioned in 1998 (see Rodwell et al. 2000). 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.  
 
Parsley fern forming part of the vegetation community amongst scree
Others have commented on the scope of the NVC and difficulties encountered in accommodating certain types of vegetation, including Cooper and MacKintosh 1996, Dargie 2000, Castle and Mileto 2003, Prosser and Wallace 2003, Averis et al. 2004, Wheeler, Shaw and Tanner 2009).
 

A compilation of proposed additions and revisions to vegetation types in the NVC has been prepared by JNCC. 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 as regards their validity and acceptance into the published NVC scheme.