Terrestrial habitat classification schemes
Classification is a prerequisite to structuring knowledge and developing our understanding of the natural world. It provides a common language through which data can be gathered, stored and communicated. A strong and consistent base of classification also provides an important tool for nature conservation. It is vital to be able to identify and record species, ecological communities and habitat types of interest that are under threat so that they can be related to a legal framework to ensure their protection.
In the case of species, there is a long-established tradition of taxonomy, which provides a single, more or less complete, classification of higher organisms found in the UK. In contrast, the requirement for the classification of habitats has only been developed in detail in recent decades. Several terrestrial and freshwater classifications have emerged as important standards for conservation in the UK. These include:
- Phase 1 Habitat Classification
- The National Vegetation Classification (NVC)
- UK Biodiversity Action Plan broad habitat and priority habitat types
- JNCC Freshwater classifications
These classification systems have been designed with somewhat different objectives in mind and use a range of different parameters for classification.
- Phase 1 habitat classification
- The National Vegetation Classification
- UK BAP Priority and Broad habitats
- Freshwater classifications
- Habitat correspondences
- Relevant publications
Phase 1 habitat classification
The Phase 1 Habitat Classification and associated field survey technique provide a standardised system to record semi-natural vegetation and other wildlife habitats. The approach is designed to cover large areas of countryside relatively rapidly. It presents the user with a basic assessment of habitat type and potential importance for nature conservation. Each habitat type/feature is identified by way of a brief description of its defining features. It is then allocated a specific name, an alpha-numeric code, and unique mapping colour.
Early work on the Phase 1 survey technique dates back to the 1970s. This was developed further in the 1980s, and in 1990 an A4 Phase 1 Handbook and supporting A5 Phase 1 Field Manual were published by the Nature Conservancy Council (NCC). Later versions of these publications (with limited additions) have been produced by JNCC. The most recent version of the Phase 1 Handbook (2006) incorporates the content of the Phase 1 Field Manual, which was originally published separately.
Since its creation, the Phase 1 technique has been used widely. Many county-wide surveys have been completed, along with many other more localised mapping projects (see Wyatt 1991). The approach is a commonly used standard in the preparation of environmental impact statements and other ecological baseline surveys.
Phase 1 habitat types
The Phase 1 classification comprises ten broad high-level categories ((A–J):
- A – Woodland and scrub
- B – Grassland and marsh
- C – Tall herb and fen
- D – Heathland
- E – Mire
- F – Swamp, marginal and inundation
- G – Open water
- H – Coastland
- I – Exposure and waste
- J – Miscellaneous
Amongst these, 155 specific habitat types are recognised, each having its own name, alpha-numeric code, description and mapping colour.
The Phase 1 Handbook
JNCC's Phase 1 Handbook contains descriptions of each of the Phase 1 habitats. The Handbook is accompanied by a spreadsheet containing all the Phase 1 habitat names and codes. This spreadsheet also contains the Phase 1 codes for dominant species and shows the additional habitat categories created for the Phase 1 Habitat Survey of Wales (NB: the latter have NOT been formally incorporated into the JNCC Phase 1 classification).
GIS Mapping tools
An ArcGIS 'style file' containing the Phase 1 colour mapping palette is available to download from JNCC's Resource Hub. This file can be extracted and applied to ArcGIS shapefiles (polygons, lines and points), using ArcGIS version 8.x or later.
For MapInfo GIS users, a Phase 1 habitat survey 'keysheet package' is available from the RSK website. This includes examples of its application and a key in PDF format. The website has instructions on its use and a contact for feedback.
BosqMap Ltd have also produced a MapInfo add-on tool for producing Phase 1 habitat maps. MapInfo fill pallet, line styles and symbols have been customised to match the styles in the Phase 1 Handbook. The software works on all MapInfo versions from 8.0 onwards.
The National Vegetation Classification
The National Vegetation Classification (NVC) is one of the key common standards developed for the country nature conservation bodies. 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. For further information on the National Vegetation Classification, visit the NVC webpage.
UK BAP Priority and Broad habitats
UK BAP Priority habitats
UK BAP priority habitats cover a wide range of semi-natural habitat types, and were those that were identified as being the most threatened and requiring conservation action under the UK Biodiversity Action Plan (UK BAP).
The original list of UK BAP priority habitats was created between 1995 and 1999. In 2007, however, a revised list was produced, following a 2-year review of UK BAP processes and priorities, which included a review of the priority species and habitats lists. Following the review, the list of UK BAP priority habitats increased from 49 to 65.
UK BAP Broad habitats
A classification of 'broad habitat' types was developed in conjunction with the development of the UK BAP priority habitats list, in order to understand how the suite of priority habitats requiring action are set within the context of the whole of the UK. Each priority habitat was to to be included within (at least) one broad habitat.
The UK BAP Broad habitats classification was developed as part of the UK Biodiversity Action Plan. The original list of 37 Broad Habitats was published in the UK Steering Group report in 1995 (Volume 2: Action Plans (Tranche 1)), and was reviewed in 1998 in the second tranche of action plans (Tranche 2 Action Plans: Volume 2 – Terrestrial and Freshwater Habitats), to ensure that the whole of the land surface of the UK and the surrounding sea to the edge of the continental shelf is covered. This resulted in a revised list of 27 Broad Habitats.
JNCC published guidance on the interpretation of Broad Habitats in JNCC Report 307 in the year 2000. This report contains the definitions for each of the terrestrial and freshwater types of the biodiversity Broad Habitat Classification. In addition to the definitions, annex 1 of the report contains tables which show the correspondence between these broad habitat types and a number of other standard habitat classifications.
For further information on UK BAP habitats, visit the UK BAP habitats webpage.
Aquatic plant communities are important ecological components of rivers and lakes. They play a complex role in the structure and functioning of these habitats. For example, they provide food and cover for fish and aquatic invertebrates, help oxygenate the water, and limit erosion.
The statutory nature conservation agencies in England, Scotland and Wales have a long history of carrying out routine aquatic plant surveys of rivers and lakes. This involves identifying and estimating the abundance of emergent, submerged, floating-leaved, and free-floating aquatic plants that grow in or near the water. The aim of this survey effort is to describe the botanical resource of rivers and lakes across Britain, help in site assessment, management and the selection of key sites, and help improve ecological understanding. This information has underpinned the selection of a representative range of river and lake types as features for protection as Sites of Special Scientific Interest (SSSIs). The process of selecting such sites requires comparison to set individual sites in a local and national context, as provided for by the JNCC's classification schemes for rivers and lakes.
This work has led to the accumulation of two large datasets held by the JNCC and two JNCC publications, which classify river and lake vegetation communities according to the composition of their aquatic plants.
The British Rivers Vegetation Communities Classification
The Vegetation Communities of British Rivers: a revised classification is based upon the composition of aquatic plant communities in rivers. It comprises three different levels of classification. Each of these is described in the publication and accompanied by a distribution map and details of the physical features and aquatic plants. A key to classify newly surveyed sites is included.
The first comprehensive classification scheme for British rivers (Holmes 1983) was based on aquatic plant surveys from 1,055 sites throughout England, Scotland and Wales. These were carried out between 1978 and 1982 by the Nature Conservancy Council. The revised classification (Holmes et al. 1999) improved on and expanded the original version with the addition of 459 new surveys and the use of TWINSPAN (Two-Way Indicator Species Analysis). In addition to classifying the sites, the TWINSPAN outputs were used to show relationships between the river groups, community types and sub-types that were identified, as well as the environmental variables related to these.
The rivers classification includes three hierarchical levels:
- River Groups: This highest level consists of four distinct broad groups (A–D) representing an environmental gradient from lowland eutrophic rivers, to those that are essentially upland, torrential and oligotrophic.
- River Community Types: This second tier of division comprises ten River Community Types (RCTs) (I–X).
- Sub-types: This final sub-division includes 38 river sub-types (AIa–DXe).
The lists below provide summary descriptions and shows how the River Groups and Community Types relate to each other:
|Group A||Lowland rivers with shallow gradients and rich geology|
|Type I||Lowland, low-gradient rivers|
|Type II||Lowland, clay-dominated rivers|
|Type III||Chalk rivers and other base-rich rivers with stable flows|
|Type IV||Impoverished lowland rivers|
|Group B||Meso-eutrophic rivers flowing predominantly over sandstone and hard limestone|
|Type V||Sandstone, mudstone and hard limestone rivers of England and Wales|
|Type VI||Sandstone, mudstone and hard limestone rivers of Scotland and northern England|
|Group C||Mesotrophic and oligo-mesotrophic rivers|
|Type VII||Mesotrophic rivers dominated by gravels, pebbles and cobbles|
|Type VIII||Oligo-mesotrophic rivers|
|Group D||Acid and nutrient-poor rivers|
|Type IX||Oligotrophic low-altitude rivers|
|Type X||Ultra-oligotrophic rivers|
The British Lakes Vegetation Communities Classification
The Vegetation Communities of British Lakes: a revised classification is based upon the composition of aquatic plant communities in lakes. It comprises eleven distinct Groups (see below), each of which is described in the publication along with a distribution map. It also includes a scoring scheme, called the Plant Lake Ecotype Index (PLEX). Changes in this index reflect the complex response of freshwater plant assemblages to a large number of environmental variables, especially alkalinity and pH.
The first comprehensive classification scheme for British lakes (Palmer 1992) was based on macrophyte surveys carried out between 1975 and 1988 by the Nature Conservancy Council (NCC). This was based on 1,124 lakes throughout England, Scotland and Wales.
Since then, the NCC and its successor organisations (Countryside Council for Wales, Natural England and Scottish Natural Heritage) have commissioned a substantial number of additional lake surveys, leading to the establishment of a much larger dataset. This includes records from 3,447 sites (310 in England, 38 in Wales and 3,099 in Scotland), the distribution of which is shown right.
The advent of the Habitats Directive and, more recently, the Water Framework Directive provided the incentive for the production of a revised classification using this larger dataset, supplemented by environmental data.
A large number of lakes fall into Group C, which is sub-divided into Groups C1 and C2 on the basis of taxon richness. The following list provides a summary description of all of these groups:
- Group A. Small, predominantly northern dystrophic peat or heathland pools, dominated by Sphagnum species.
- Group B. Widespread, usually low-lying acid moorland or heathland pools and small lakes, with a limited range of plants, especially Juncus bulbosus, Potamogeton polygonifolius and Sphagnum species.
- Group C1. Northern, usually small to medium-sized, acid, largely mountain lakes, with a limited range of plants, but Juncus bulbosus and Sparganium angustifolium constant.
- Group C2. North western, predominantly large, slightly acid, upland lakes, supporting a diversity of plant species, Juncus bulbosus constant, often with Littorella uniflora and Lobelia dortmanna, in association with Myriophyllum alterniflorum.
- Group D. Widespread, often large, mid-altitude circumneutral lakes, with a high diversity of plants, including Littorella uniflora, Myriophyllum alterniflorum, Callitriche hamulata, Fontinalis antipyretica and Glyceria fluitans.
- Group E. Northern, often large, low altitude and coastal, above-neutral lakes with high diversity of plant species, including Littorella uniflora, Myriophyllum alterniflorum, Potamogeton perfoliatus and Chara species.
- Group F. Widespread, usually medium-sized, lowland, above neutral lakes, with a limited range of species, but typified by water-lilies and other floating-leaved vegetation.
- Group G. Central and eastern, above neutral, lowland lakes, with Lemna minor, Elodea canadensis, Potamogeton natans and Persicaria amphibia.
- Group H. Northern, small, circumneutral, lowland lakes, with low species diversity characterised by the presence of Glyceria fluitans and Callitriche stagnalis.
- Group I. Widespread, mostly moderately large, base-rich lowland lakes, with Chara species, Myriophyllum spicatum and a diversity of Potamogeton species.
- Group J. Northern coastal, brackish lakes, with Potamogeton pectinatus, Enteromorpha species, Ruppia maritima and fucoid algae.
There are a number of popular terrestrial, freshwater and marine habitat and vegetation classifications in use. These classification systems have been designed with different objectives in mind and use a range of different parameters for classification. The correspondences that have been identified between these and certain other systems are presented in an interactive spreadsheet.
Note that this spreadsheet was produced in 2008 and has not been updated since.
Phase 1 habitat survey – related publications
Blackstock, T.H., Burrows, C.R., Howe, E.A., Stevens, D.P. and Stevens, J.P. 2007. Habitat inventory at a regional scale: a comparison of estimates of terrestrial Broad Habitat cover from stratified sample field survey and full census field survey for Wales, U.K. Journal of Environmental Management, 85, 224–31.
Blackstock, T.H., Stevens, J.P., Howe, E.A. and Stevens, D.P. 1995. Changes in the extent and fragmentation of heathland and other semi-natural habitats between 1920-22 and 1987-88 in the Llŷn Peninsula, Wales, UK. Biological Conservation, 72, 33–44.
Cherrill, A.J. and McClean, C. 1999. Between observer variation in the application of a standard method of habitat mapping by environmental consultants in the UK. Journal of Applied Ecology, 36, 989–1008
Cherrill, A.J. and McClean, C. 1999. The reliability of Phase 1 habitat mapping in the UK: the extent and types of observer bias. Landscape and Urban Planning, 45, 131–43.
Dargie, T. 1993. Repeat Phase 1 habitat survey and detection of vegetation change. English Nature Research Reports 51. English Nature, Peterborough.
Howe, L., Blackstock, T., Burrows, C. and Stevens, J. 2005. The Habitat Survey of Wales. British Wildlife, 16, 153–62.
Stevens, J.P., Blackstock, T.H., Howe, E.A. and Stevens, D.P. 2004. Repeatability of Phase 1 habitat survey. Journal of Environmental Management, 73, 53–9.
Wyatt, G. 1991. A Review of Phase 1 Habitat Survey in England. England Field Unit, Nature Conservancy Council.
Yeo, M.J.M. and Blackstock, T.H. 2002. A vegetation analysis of the pastoral landscapes of upland Wales, UK. Journal of Vegetation Science, 13, 803–16.
British Rivers Vegetation Communities – related publications
Holmes, N.T.H., Boon, P.J. & Rowell, T.A. 1998. A revised classification system for British rivers based on their aquatic plant communities. Aquatic Conservation: Marine and Freshwater Ecosystems, 8, 555–78.
Holmes, N.T.H. 1983. Typing British rivers according to their flora. Peterborough, Nature Conservancy Council. (Focus on nature conservation, No 4.) NB: this is the original 1983 NCC classification for rivers, which is now out of print.
British Lakes Vegetation Communities – related publications
Duigan, C., Kovach, W. & Palmer, M. 2007. Vegetation communities of British lakes: a revised classification scheme for conservation. Aquatic Conservation: Marine and Freshwater Ecosystems, 17, 147–173.
Duigan, C., Kovach, W. & Palmer, M. 2008. Aquatic macrophyte classification, distribution, and traits in British lakes. Verh. Internat. Verein. Limnol, 30, 477–481.
Palmer, M. 1992. A botanical classification of standing waters in Great Britain and a method for the use of macrophyte flora in assessing changes in water quality. Peterborough, Joint Nature Conservation Committee. (Research and Survey in Nature Conservation, No. 19.)*
Palmer, M.A., Bell, S.A. & Butterfield, I. 1992. A botanical classification of standing waters in Britain: applications for conservation and monitoring. Aquatic Conservation: Marine and Freshwater Ecosystems, 2, 125–143.*
* these two publications relate to the original 1992 JNCC Classification of Lake Vegetation Communities.