Since 1978, a series of national surveys (Countryside Survey, CS) have been
carried out by the Centre for Ecology and Hydrology (CEH) (formerly the Institute
of Terrestrial Ecology, ITE) to gather data on the natural environment in Great
Britain (GB). As the sampling framework for these surveys is not optimised to
yield data on rarer or more localised habitats, a survey was commissioned by
the then Department of the Environment (DOE, now the Department for
Environment, Food and Rural Affairs, DEFRA) in the 1990s to carry out
additional survey work in English landscapes which contained semi-natural
habitats that were perceived to be under threat, or which represented areas
of concern to the ministry. The landscapes were lowland heath, chalk and
limestone (calcareous) grasslands, coasts and uplands. The information
recorded allowed an assessment of the extent and quality of a range of
habitats defined during the project, which can now be translated into
standard UK broad and priority habitat classes. The survey, known as the
“Key Habitat Survey”, followed a design which was a series of gridded,
stratified, randomly selected 1 km squares taken as representative of each
of the four landscape types in England, determined from statistical land
classification and geological data (“spatial masks”). The definitions of
the landscapes are given in the descriptions of the spatial masks, along with
definitions of the surveyed habitats. A total of 213 of the 1 km
In Great Britain (GB), monitoring of ecological and land cover
change has been carried out since 1978 via a programme named Countryside
Survey (CS) (
In England, the former Department of the Environment (DOE) commissioned ITE (now part of CEH) to undertake a research project (Hornung et al., 1997) to quantify and evaluate the quality of the rarer semi-natural habitats of England not specifically covered by the more general monitoring CS provides, as a consequence of the widespread concern expressed over previous decades regarding the loss of semi-natural habitats, many of high nature conservation value. There has been considerable debate, particularly across Europe, about the relative importance of various drivers causing these losses, including changes in land use or farming practices, climate change, atmospheric pollution, or industrial and urban development.
Named as the “Key Habitat Survey” by ITE, the survey recorded vegetation species, land cover, landscape features and land use information from 1 km sample square sites occurring within the landscape types included as targets for conservation action in the original Countryside Stewardship Scheme (CSS) (Countryside Stewardship, 2017), an English grant scheme intended to reward farmers for farming land for nature conservation. The survey used established methods based on the standardised CS methods, as described below. In a variation to the standard CS methods, information was largely recorded from points falling on grid intersections within each 1 km square site, whereas, in CS, landscape area, point and line features are mapped across whole of 1 km square site, with vegetation plots being recorded at randomly placed points (i.e. not gridded) (Wood et al., 2017).
Standard habitat classes in Britain have evolved since the time of the Key Habitat Survey and can now be defined as broad (Jackson, 2000) and priority (Maddock, 2008) habitats. At the time of the project, a range of different customised land cover and habitat groupings were used to report the results of the survey. However, the data were recorded in such a way as to make it possible to translate information into the standard broad and priority habitat groupings, or European Annex I Classes as required (Romão, 2013). The “key habitats” term quoted in the title of the survey was derived from the term “key habitats” as included in the biodiversity action plans (UK Biodiversity Steering Group, 1995), which were later to evolve into the broad and priority habitat framework.
The surveyed landscape types were lowland heath landscapes, chalk and limestone (calcareous) grassland landscapes, coastal landscapes and upland landscapes. The main aims of the project were to determine the extent of a range of land cover types within each landscape type, to assess their ecological status and to establish a baseline for long-term monitoring of ecological change. All of the surveyed landscape types, together with their constituent broad and priority habitats, were seen as areas which had suffered serious losses and habitat degradation in the past and appeared to be still under threat. They were also perceived as having major significance for wildlife, landscape, archaeology and amenity criteria.
Information regarding specific habitats has become increasingly available through thematic and local surveys and inventories, such as Natural England surveys (Wilson et al., 2013; exegesis SDM Ltd. and Doody, 2009; Doody and Rooney, 2015; Jerram et al., 1998) and collation of information on lowland heath and calcareous grasslands (Marrs et al., 1986; Rose et al., 2000; Gibson and Brown, 1991; Moore, 1962). However, an important point is that the data from the Key Habitat Survey cover a range of the less common land cover and habitat types and offer an additional element to the long-term national monitoring programme of the Countryside Survey, both by providing additional data to augment the wealth of long-term ecological data already collected by the programme and by offering an additional targeted sampling framework, which could be incorporated into the Countryside Survey field survey should resources become available.
The data have hitherto remained unpublished, aside from the information in contract reports written following the field survey (Barr, 1996a, b, c, d). It is therefore timely that these data are now being made available for wider use.
There are a number of long-term national monitoring projects for widespread and more common habitats, particularly across Europe, for example in Switzerland (Hintermann et al., 2002), Norway (Dramstad et al., 2002) and Sweden (Ståhl et al., 2011), as well as globally (United States Forest Service, 2015; Wiser et al., 2001; Gillis et al., 2005). Local studies of specific habitats or specific species are also frequent in many countries, for example in Europe: peatlands in Slovakia (Špulerová, 2009), dunes in Belgium (Provoost et al., 2004), hay meadows in France (Broyer and Curtet, 2005), coastal monitoring in Ireland (Ryle et al., 2007) and other examples, which can be viewed in the EuMon database (EuMon, 2017). Beyond Europe, many other vegetation studies have also been undertaken, for example in Belize (Bridgewater et al., 2002) and Borneo (Aiba and Kitayama, 1999). In Britain, there are a range of examples of studies carried out in the last 50 years regarding the ecologically valuable landscapes covered by the Key Habitat Survey (Dargie, 1993, 1995; Radley and Dargie, 1994; Sneddon et al., 1994; Stevens et al., 2007). However, these studies specifically target individual habitat types, usually at a local level.
The Key Habitat Survey targeted a range of different, less common land cover and habitat types, contributing an additional element to the national ecological monitoring programme Countryside Survey, which provides a wide range of nationally significant ecological datasets, globally unique in their geographical coverage and time span. Other examples of structured, standardised, repeatable ecological data, targeted at a wide range of rare and localised habitats at a national level, are not known to the authors. The survey employs repeatable methods and is also designed in such a way as to add value to the Countryside Survey by offering additional targeted information regarding rarer and more localised habitats, which CS does not provide. The data regarding land cover, landscape features and vegetation collected during the survey offer detailed information with which to assess the quality and extent of the rarer broad and priority habitat types.
The Key Habitat Survey focused on the following landscapes: lowland heath landscapes, chalk and limestone (calcareous) grassland landscapes, coastal landscapes and upland landscapes. The choice of landscapes selected for survey was determined by their inclusion in the original Countryside Stewardship Scheme launched in 1991 in England. CSS was a grant scheme that offered payments to farmers and other land managers in order to make conservation part of normal farming and land management practice. The stated objectives of the scheme were to sustain the beauty and diversity of the landscape, improve and extend wildlife habitats, conserve archaeological sites and historic features, improve opportunities for countryside enjoyment, restore neglected land or features, and create new wildlife habitats and landscape features (Ovenden et al., 1998).
The lowland heath, calcareous and coastal landscapes are characterised to a greater or lesser extent by a mosaic of land cover types, including a variety of habitats. Thus, for example, lowland heath and calcareous grassland are the core broad and priority habitats occurring in the respective landscapes, but the landscapes also include many non-heath and non-calcareous grassland broad habitats (Jackson, 2000) (for example fen, marsh and swamp, neutral grassland and broadleaved woodland). Similarly, the upland and coastal landscapes include a range of habitats which are characteristically upland and coastal, in addition to other associated habitats.
The descriptions below highlight the importance of each landscape in containing broad, and particularly priority, habitats of high conservation value in a national, and in some cases international context, in addition to being valued scenically and recreationally.
European heaths are widely recognised to be of high conservation value, as
shown by their inclusion in Annex I of the EU Habitats Directive. The list
includes Annex I habitats “4010: Northern Atlantic wet heaths with
The distribution of the lowland heath landscapes is largely controlled by particular combinations of geology and soils with lowland heath occurring on acidic, often podzolic soils that are low in nutrients, mainly as a result of soil deterioration in prehistoric times. However, important bog and wet heath habitats in the lowland heath landscape are associated with wetter acid soils.
Lowland heaths have become the focus of increasing conservation concern as a
result of high rates of loss and degradation. For example in Sweden and
Denmark, the area of this habitat declined by 60–70 % in the century
prior to the 1960s, with the corresponding decline for the Netherlands being
95 % (Farrell, 1989). The survival of the distinctive lowland heath
vegetation and habitats, dominated by heather (
In England, the largest remnants are concentrated in the New Forest, Breckland, the Suffolk Sandlings, East Hampshire, Surrey, Dorset and the Lizard.
Calcareous grasslands are associated with shallow, calcareous soils overlying limestone and chalk bedrock. The type of grassland varies with the type of underlying calcium-rich bedrock, with the principle division being between the chalk grasslands on soft substrates in the south and east of England and the limestone grasslands occurring on harder Carboniferous strata in the north and west of Britain.
Calcareous grasslands are botanically rich, being amongst the most species-rich and species-diverse plant communities in Britain and northern Europe. In Annex I of the EU Habitats Directive, the following are included: “6210/6211, Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia) (including important orchid sites)”. Within Britain, the large number of plant species occurring in calcareous grassland constitutes a substantial percentage of the total native flora (estimated at 10–20 %) and many of the plant species are scarce native species; a total of 77 protected or listed species occur in calcareous grassland, of which 50 are restricted to calcareous grassland only (Keymer and Leach, 1990). In addition, calcareous grasslands (especially on the warm South Downs) provide habitats for many invertebrates including ants and butterflies which are confined to this region and are scarce or localised in Britain. In contrast to lowland heaths, England only contains a small part of the European stock of calcareous grassland; such grasslands occur over much of central and northern Europe. However, their rarity in Britain makes them a nationally important resource and they are listed as priority habitats “upland calcareous grassland” and “lowland calcareous grassland” (Maddock, 2008).
The extent of calcareous grassland is thought to have reached a maximum 300 years ago. Since then, large areas have been lost, with substantial losses occurring within the last 70 years (Poschlod and WallisDeVries, 2002; Fuller, 1987). The introduction of seeding agricultural grassland after 1700 led to a decline in the quality of some chalk grassland, and as farming became mechanised in the early 19th century, many grasslands were ploughed up. During the 20th century many calcareous grasslands have been lost to arable or improved pasture, mineral extraction, afforestation and building development. Keymer and Leach (1990) suggested that between 1968 and 1980 the loss of grassland was about 60 % due to ploughing or agricultural improvement, about 30 % to scrub encroachment and 1 % due to development. As most calcareous grassland remains in agricultural ownership, the impact of changes in agricultural management is significant and grazing is the dominant influence in the maintenance of calcareous grassland. In England, the largest areas are in the south, such as Salisbury Plain, and the North and South Downs. They also occur in Yorkshire, Derbyshire, Morecambe Bay and County Durham.
Coastal habitats and land cover types tend to be dynamic compared to those in the other surveyed landscapes. Geology is a major factor determining the type of coastal landscape and the constituent habitats, with the major division being between soft and hard rock coasts, with the former associated with salt marshes and low earth cliffs and the latter with rocky foreshores and cliffs. Within these major divisions there is a mosaic of habitat types. Early successional plant communities are particularly important in the coastal zone, in comparison to the other landscapes. Many of the habitats in the coastal landscape are of restricted occurrence and contain rare species. Stewart et al. (1994) estimate that at least 20 % of the nationally scarce plants (Joint Nature Conservation Committee, 2018) in Britain are coastal. Coastal habitats listed as priority habitats in the UK biodiversity action plan (Maddock, 2008) include coastal and floodplain grazing marsh, coastal salt marsh, coastal sand dunes, coastal vegetated shingle, maritime cliff and slopes, and intertidal mudflats. The UK has special responsibility (as it holds a large proportion of the European resource) for several coastal habitats listed in the EU Habitats Directive, including “1230: Vegetated sea cliffs of the Atlantic and Baltic coasts”, “1160: Large shallow inlets and bays” and “1130: Estuaries”.
Coastal landscapes have often been heavily influenced by man, although some of the core maritime habitats are formed naturally. The coastal belt is particularly well used for a wide variety of recreational activities. The detailed mix of species and the mosaic of habitats (including cliffs, estuaries, mud-flats and beaches) are inevitably influenced by the management and use of the landscapes.
In the uplands, the interaction between the underlying soils, geology and climate determine the collection of habitats which make up the landscape. This landscape occurs largely in the north of the country, extending from Northumberland to the Pennines, Yorkshire Dales, Derbyshire and Lake District, but with important outliers in the south-west, notably Dartmoor and Exmoor.
The combination of montane and oceanic climatic conditions gives rise to
plant communities which are of restricted distribution in Europe. Although
the habitats are relatively species poor, they are often present as large
continuous units extending over extensive expanses of land, which are rare
elsewhere in Britain. They therefore support species of birds that might not
persist in smaller, more fragmented habitats, such as hen harriers
(
Much of the upland landscape has been dominated by upland heaths and bogs since the Iron Age (Tallis, 1991). It would also have been forested at some point since the last glacial period. Whilst management, grazing and burning are important in maintaining the mix of habitats in the uplands, it is not likely that reversion to scrub or woodland would occur in all the formerly wooded areas, due to peat formation and the current climate.
The overall design of the Key Habitat Survey, in principle, follows the standardised procedures described by Bunce and Shaw (1973). The methods are utilised in the national Countryside Survey 1978–2007 (Carey et al., 2008) and also the recent Welsh Glastir Monitoring and Evaluation Programme 2013–2016 (Emmett and GMEP team, 2017). The methods have also been successfully deployed in a range of British regional surveys (Wood and Bunce, 2016; Bunce and Smith, 1978; Wood et al., 2015). A comparison of the sampling approaches used in both the Countryside Survey and the Key Habitat Survey is given in Table 1.
In the same way to CS, the Key Habitat Survey uses a sampling approach, with random samples of 1 km squares being selected for survey from a statistical environmental classification to enable robust estimates of areas to be produced. This stratified, random strategy ensures adequate representation of the range of ecological variation within the landscapes. Whereas CS uses the ITE Land Classification to form a sampling framework for the GB Countryside Survey (Bunce et al., 1996a), the Key Habitat Survey uses a more targeted set of “spatial masks” to stratify the samples for each landscape type (incorporating the ITE Land Classification to some extent). The ITE Land Classification was initially developed in the late 1970s and uses a range of environmental variables such as altitude, climate, geology, human geography and location. Using multivariate analysis, GB was split into a set of 32 land classes (or strata), from which the 1 km survey squares could be randomly selected.
Distribution of spatial landscape masks and 1 km square survey sites.
Table showing a comparison between the Countryside Survey and the Key Habitat Survey.
In terms of the Key Habitat Survey, only fragmentary information existed at the start of the project from which to define and map the national distribution of the landscapes. Procedures were therefore developed to create a mask for each landscape which defined those 1 km squares in England, which contained, or had the potential for containing, the characteristic habitats of that particular landscape, thus providing the environmental classification required for the stratification framework (Fig. 1 and Table 2). Nature sites and areas of countryside can be “designated”, which means they have special status as protected areas because of their natural and cultural importance (Government Digital Service, 2018). Additional information regarding UK designation (designated or non-designated) (Natural England, 2017a) was also utilised to facilitate the choice of 1 km survey squares. In this context designated refers to the following: site of special scientific interest (SSSI), national nature reserve (NNR), national park (NP), area of outstanding natural beauty (AONB), heritage coast (HC), green belt, and environmentally sensitive areas (ESA). The 1 km sample squares were drawn at random from within the landscape masks and randomly sampled (Fig. 1) with land cover, vegetation in quadrats and landscape elements being recorded in field surveys. Historic features were also recorded but are beyond the scope of this paper. The location of the vegetation quadrats was permanently marked to facilitate resurvey. In total, 213 squares were surveyed across England.
Summary of the spatial landscape mask definitions. SSLRC is the Soil Survey and Land Research Centre
The lowland heath landscape mask contains existing and potential areas of what could now be classed as the priority habitat, “lowland heath”. The mask was constructed by combining data on soils and altitude. Soil types characteristic of lowland heath vegetation and landscapes were used to define a population of 1 km squares having potential for heath. A 1 km dataset of the Soil Survey and Land Research Centre (Cranfield University, 2017) provided data in digital form on dominant and sub-dominant soils within 1 km grid squares. Soil types most likely to support heath vegetation were identified, along with the soil types appearing in areas of known heaths. Peat soils were also included as these have a potential for heaths, especially in the vicinity of existing heathland. A full list of soil types used is given in the supporting documentation accompanying the dataset.
Soils data alone cannot be used to differentiate between upland and lowland
heaths, and neither can lowland heath simply be defined in terms of altitude. As
climate varies in different parts of England, that which might be considered
upland vegetation in some places may occur at relatively low altitudes
in harsher environments. Thus, whereas the lowland–upland vegetation
interface may be considered to occur somewhere in the region of 200–300 m
in the south of England, in the north characteristically upland
vegetation may occur in areas around sea level. In order to overcome these
regional differences, we made use of the ITE Land Classification 1990 (Bunce
et al., 1990). This consists of a statistical environmental classification
covering the whole of Great Britain, created by the multivariate analysis of
environmental factors, for example altitude and climate, from each 1 km
square in the country (Bunce et al., 1996b). This classification used a range
of environmental and physical parameters to assign all the 1 km squares in
Great Britain into one of 32 land classes; land classes 17–24 and 27–28
which are characteristically upland in nature were used to exclude areas
of England unlikely to contain lowland heath landscape areas. Coastal
heathlands are poorly covered by this mask because they tend to be small and
difficult to associate with soil types marked on the
The calcareous grassland landscape mask covers 26 555 km
Data collected regarding land cover and area features.
The coastal landscape mask was defined as that area of land extending 500 m
inland from the mean high water mark (HWM) plus all contiguous areas of salt
marsh, dunes and coastal bare land. The 25 m resolution Land Cover Map 1990,
a satellite-derived map of UK land cover types (Fuller et al., 1993), gave
the location of the HWM and this was chosen for use. A coastal buffer was
defined as a set of contiguous 1 km grid cells in England where coastal
attributes (i.e. coastal buffer, salt marsh or coastal bare) were present. In
total, 8870 km squares were
covered in some part by the coastal zone. Of these, 787 urban squares (
Again, it was not adequate to simply define the upland landscape by altitude
alone. To allow for the inherent variation in land above certain altitudes in
different parts of England, the upland mask was derived from the ITE Land
Classification 1990 (Bunce et al., 1990), as this stratification provides an
overall integration between the critical environmental factors. As described
above, the predominantly upland classes include 17–24 and 27–28 and thus
were used as the basis of the mask. Squares which were predominantly urban
(51) were excluded, providing a mask area of 15 616 km
The lowland heath landscapes were surveyed in the summer of 1992, with the remaining three landscape types surveyed in 1993. In a variation to the Countryside Survey methodology (Maskell et al., 2008a, b), information was collected based on a grid-based sampling framework within each 1 km square survey site, as shown in Fig. 2. Coastal and lowland heath landscapes used a 25-point grid, and calcareous and upland landscapes used a 16-point grid. Grid points were marked on base maps and located in the field using measurements and bearings from prominent features.
Rules were in place for relocating points falling on linear features or in urban land. The detailed rules for relocation are given in the field handbooks (Barr, 1992, 1993), although the general rule meant moving the point 10 m away from the original grid point where possible.
With maximum resource, the ideal survey methodology would follow exactly the methods of the Countryside Survey as described in Wood et al. (2017, 2018) in order to obtain the most comprehensive dataset for a full understanding of the landscapes in question. In terms of the land cover and boundary data, this would mean that the whole of each 1 km survey square site would be fully mapped with landscape point, line and area features. Whilst the grid-based approach has the potential to save time in the field, much information regarding structure and pattern is lost. A further assessment of alternative methods is described in Wood et al. (2018). In terms of the vegetation data, the approach taken has been proven as being highly effective for assessing the quality of vegetation at a national scale, as described in Wood et al. (2017).
Land cover at each grid point in each square was described using a
comprehensive list of land use and land cover codes, as used in Countryside
Survey 1990 (Barr, 1990). Recorded attributes are summarised in Table 3. All
mappable units included a primary description of the feature in question (for
example maritime grassland, fen, scrub), along with dominant species
(
Data collected regarding boundaries.
The nearest vertical boundary (measuring
Sampling of vegetation from within quadrats (i.e. plots) largely used the methodology followed by the Countryside Survey (Wood et al., 2017) with variations as detailed below. At each plot, the slope, aspect, shade, general soil type and descriptions were recorded. A summary of the number and locations of plots recorded is given in Tables 5 and 6.
In each plot, a complete list of all vascular plants and a selected range of readily identifiable bryophytes and macro-lichens was made. The field training course held before the surveys covered identification of difficult species, regular visits were made to survey teams by managers, and difficult specimens could be collected and sent to experts for identification. Cover estimates were made to the nearest 5 % for all species reaching at least an estimated 5 % cover. Presence was recorded if cover was less than 5 %. Predetermined combinations of species may have been recorded as aggregates reflecting known difficulties in their separation in the field (refer to Barr, 1993).
Summary of vegetation plot locations.
Summary of vegetation plots recorded.
The term “X plot” is used to denote plots located at predetermined,
dispersed random sampling points. In this survey, 2 different sizes of X plot
were used, 4 and 200 m
These small plots were only recorded in the lowland heath and calcareous
landscape types. In lowland heath landscapes, a 4 m
These large, 200 m
The methodology for 200 m
Five of these small targeted plots were placed in each square in semi-natural vegetation types that were not covered by the main (X) plots. These type of plots were used in 1993, in the coastal, upland and calcareous surveys. The five plots were placed randomly in five different land cover types where available, additional to those types already represented by the five randomly located (X) plots. If there were more than five land cover types available, priority was given first to those most typical of the landscape type, and second to the size of the area in question. If there were fewer than five land cover types, plots were placed proportionally to the number of land cover types available. These Y plots were important in sampling fragments of semi-natural habitat particularly in lowland landscapes, where patches may be small and embedded in a matrix of intensive farmland. Of all the plots recorded, they are most similar to the approach taken when positioning relevés (quadrats) during national vegetation classification (NVC) (Rodwell, 2006) because their location is not pre-determined.
Up to five of these linear (
Up to five of these linear (
Gridded sampling structure for 1 km survey squares. Vegetation plots were recorded as shown, with land cover and boundary features being recorded at every grid intersection point in each square.
Work was carried out to validate the masks (mainly the calcareous and lowland heath) through comparisons with other datasets, although none of these provided definitive or directly comparable data for validation purposes. As the coastal and upland masks were more straightforward to define geographically, and the best available relevant data (at the time) were used in defining the masks, comparisons with other data were therefore not appropriate. The calcareous mask was compared against soils data (Mackney et al., 1983), as well as the former English Nature (EN) database on calcareous sites (Natural England, 2017b). The lowland heath was compared to the satellite-derived Land Cover Map 1990 (Fuller et al., 1993) and to English Nature lowland heath sites (Natural England, 2017b). Overall, the lack of resolution resulting from the use of the 1 km square geological data caused some discrepancies in comparison with these other datasets. However, at the time, this was the only geological dataset available for use in the project (higher-resolution geological data were in existence). In terms of the calcareous mask, the match with the English Nature data was good, covering 89 % of the EN chalk sites and 87 % of the EN limestone sites. The lowland heath mask covered only 55 % of the lowland heathland sites registered by English Nature. Most of the sites not covered by the lowland heath mask are scattered throughout England, but there is a particularly poor coverage in areas of Hampshire and Cornwall. In these areas, the missing sites occur on 1 km squares with dominant or subdominant soil types which are not specific to lowland heathland, and it was not possible to improve the coverage of the lowland heath mask without greatly increasing its size to cover large areas of England with little or no heathland potential. The map of lowland heathland areas derived using only soils and land class data therefore missed many small pockets of heathlands. However, with the exception of coastal heathlands, and areas in the New Forest and Cornwall where there are several mismatches between the Land Cover Map 1990 and English Nature's reference database and the lowland heathland map, most areas of existing heathlands were adequately covered.
The overall conclusion was that, although there were some mismatches between the masks and other datasets, the fit was judged to be acceptable for the purposes of the project in providing an adequate sampling framework. Whilst it is acknowledged that with the increased quality and availability of digital data the masks could be improved, a key aim of the sampling framework (heavily based on the ITE Land Classification) is that it provides an objective and static sampling framework, independent of specific environmental indicators being measured. As the underpinning data used in the classification is static over time, the classes themselves will not change and repeat surveys and repeat analyses are possible and easily comparable. The consistency in sampling protocols is crucial for robust, repeat analyses.
Several approaches were used to maintain quality in field recording and to minimise variation between surveyors. The field surveys were carried out by teams of experienced botanical surveyors and were preceded by intensive training courses, ensuring high standards and consistency of methodology, effort, identification and recording across the survey according to criteria laid out in the field handbooks (Barr, 1992, 1993). During the surveys, survey teams were initially supervised and later monitored by experienced project staff in order to control data quality. Data were recorded on waterproof paper sheets and were consequently transferred from the original field sheets to spreadsheets, using a “double-punch” method to minimise errors in data entry. They were checked using range and format checks and corrected to produce a final validated copy.
During the field survey, independent ecological consultants revisited a sample of the survey squares and repeated quadrats and land cover descriptions. The unpublished results show a 74.3 % accuracy rate in the recording of vegetation plots, comparable to the CS 1990 accuracy of 74–83 % (Prosser and Wallace, 1992). Information from these repeat visits was given to surveyors so that consistency of recording was maintained.
During the surveys, plot locations were recorded on paper using a sketch map with measurements from distinguishing landscape features and by taking at least two photographs, preferably also including key landscape features in proximity to the plot. In addition to these, permanent metal plates or wooden stakes were placed in the ground to mark the plot locations. These steps were taken in order to facilitate any potential future visits to the plots.
The methods used to mark plots are identical to the methods used in Countryside Survey which have been widely tested and shown to be robust. The CS plots are estimated to have a precise relocation accuracy of 85–86 % (Prosser and Wallace, 2008), and, in the event of a resurvey of these key habitat plots, it would be expected that the plot relocation accuracy would be similar.
At the present time, the results of the survey have been restricted to a set of contract reports, published in 1996 (Barr, 1996a, b, c, d). The previous unavailability of the data has so far resulted in limited use of the datasets, although one example has been the incorporation of the plot data in the niche models included in the Multimove package (Henrys et al., 2015), which enables users to make predictions of species occurrence from specified environmental data and allows the plotting of relationships between the occurrence of species and individual environmental covariates. A summary of the key findings reported in the 1996 reports is described in the following sections; however, the potential for further analyses is high.
Estimates of broad habitat extents for each landscape type from the Key Habitat Survey and, for comparative purposes, in England as a whole from the Countryside Survey. Broad habitats characteristic of a landscape type are given in bold. Note that categories in italics are customised definitions used within the project rather than standard broad or priority habitats (those in bold are characteristic of a landscape).
Summary of boundaries by landscape type as a proportion of the total
(
Following the Key Habitat Survey, results of stock estimates (extents) were presented in terms of land cover classes, based on those used in CS 1990 (Barr et al., 1993). Methods of classifying land cover types have since evolved (e.g. Wyatt et al., 1994). It is now possible to present estimates of habitats present in each landscape in terms of standard UK broad habitats (Jackson, 2000) and, in some cases, priority habitats. The data also offer the potential for additional work in terms of exploring priority habitats in more detail. The recorded field codes and the original land cover classes can be translated to broad habitat categories using the information presented in Table S1. Table 7 gives a summary of the broad habitat area extents (with additional coastal habitats defined in Hornung et al., 1997) provided by the Key Habitat Survey. For the purposes of comparison, the table also includes estimates for the whole of England from the national Countryside Survey (Carey et al., 2008).
In the lowland heath, calcareous grassland and coastal landscapes, only a small proportion of the landscape masks were estimated to be habitats characteristic of the landscape type (figures shown in bold in Table 7). For lowland heath: 5.2 % (dwarf shrub heath); calcareous: 1.6 % (calcareous grassland) and coastal: 11.6 % (supra-littoral rock, supra-littoral sediment, littoral sediment). The large proportion of the upland landscape which comprises characteristic habitats (56.5 %, acid grassland/bracken; dwarf shrub heath; fen, marsh and swamp; bog) reflects the less intensive use of the uplands and the extensive nature of many of the upland habitats.
More than a half of the total areas of the calcareous grassland, lowland heath and coastal landscape masks were under arable crops or managed grassland (arable and horticulture, improved/neutral grassland), reflecting the predominantly lowland distribution of these landscapes and previous intensification of agriculture (for example, Chamberlain et al., 2000). In contrast to the other landscapes, only a small proportion of the upland landscape area was classed as arable and horticulture (1.4 %), with a large proportion of the land cover consisting of semi-natural vegetation; crops were only recorded in the marginal uplands. The largest area of urban broad habitat was found in the coastal landscape (27.2 %) showing the extent of urban development in the coastal zone. The largest area of woodland (broadleaved, mixed and yew/coniferous woodland) occurred in the lowland heath mask (20.1 %) and the smallest in the coastal mask (5 %).
Figures from the Countryside Survey enable an assessment of the amount of each broad habitat within each landscape covered by the Key Habitat Survey compared with national figures for the whole of England. In the case of dwarf shrub heath, Countryside Survey estimates a stock of 331 000 ha in England. The survey of dwarf shrub heath in the lowland heathland (44 000 ha) and upland landscapes (279 000 ha) in the Key Habitat Survey gives a lower overall estimate than CS, at 323 000 ha, indicating that perhaps some small areas of heath were missed during the Key Habitat Survey. The upland habitats (incorporating acid grassland, bracken, dwarf shrub heath and bog) are covered well by the Key Habitat Survey, covering 84.3–99.3 % of the total England areas. A total of 36.8 % of the fen, marsh and swamp habitat was found in the upland areas (but is also present in lowland areas). In terms of the calcareous grassland landscape, the Key Habitat Survey estimates a total of 43 000 ha in comparison with a CS total of 30 000 ha. This perhaps confirms the fact that CS is not designed to effectively monitor or survey less common habitats such as this (Morton et al., 2011).
In the original survey reports, analysis indicated that, overall, the vegetation of the coastal landscape was the most sensitive to the changes considered (such as arable intensification, urban development, climate change, and recreation pressure). In all four landscapes, it was found that the majority of high-quality habitats were located within protected areas, potentially demonstrating the effectiveness of designation in restricting habitat loss (Hornung et al., 1997).
Mean number of species in each habitat indicator group per plot in each landscape type in the Key Habitat Survey, with an indication of broad (BH) and priority (PH) habitats where appropriate. Habitat indicator groups characteristic of a landscape type are given in bold.
The proportion of different boundary types recorded in each of the landscape masks is shown in Table 8, including the proportion of points for which there was (or was not) a boundary within 100 m. In calcareous, coastal and lowland heath landscapes, fences are the most frequent boundary type, accounting for 42–43 % of all boundaries. In the uplands, fences accounted for 33 % of all boundaries, whereas walls formed 36 %. Combinations of walls and fences accounted for a further 23 %.
Field boundaries were most common in the calcareous and lowland heath landscape areas, with 68 % of points having a boundary within 100 m, reflecting field size, cropping practices and the presence of urban features (including roads).
In coastal land, only 45 % of all grid points had a boundary within 100 m. Squares in protected, designated land had a lower proportion of field boundaries, indicating the greater areas of unenclosed parcels on protected land.
In the uplands, 63 % of all grid points had a boundary within 100 m. There was a clear difference between strata in the number of boundaries. Additional analyses showed the squares in the true uplands had a lower proportion of field boundaries, showing the greater areas of unenclosed land (heath and woodland) (Barr, 1996c). In designated land, and the non-designated marginal land, walls (with or without fences) formed the most frequent boundary type, followed by fences, but, in the non-designated true upland land, walls were less common and fences formed the predominant boundary type. Only 7 % of boundaries in the uplands included hedges.
The range of vegetation present is described using a classification of plants derived from statistical clustering of the species scores from DECORANA (Hill, 1979) axes into “habitat indicator groups”, later developed as the Countryside Vegetation System, as described by Bunce et al. (1999). This term was coined in conjunction with the Department of the Environment, and their occurrence helps to interpret the ecological characteristics of the landscapes. The mean number of species in each of these habitat indicator groups per plot for each landscape type is shown in Table 9, along with the proportion of species in each indicator group in comparison with the total. An indication of the current broad (BH) or priority habitat (PH) to which the habitat indicator group equates is given in Table 9. Although the proportion of species from each indicator group falling into each landscape type in many cases reflects the overall extent of that type (figures in bold in Table 9), it also reflects the extent of fragmentation of some vegetation types, thus giving an indication of the quality of that type. The characteristic vegetation types were well represented in the main plots in the uplands, showing that they occur as relatively large areas. The uplands were dominated by moorland (23–29 %), bog (8–10 %), and upland grassland (14–17 %) species, but also include a variety of more lowland indicator groups, such as neutral and improved grassland species (27 %) as well as woodland species (8 %).
In calcareous landscapes, the proportion of species from the calcareous grassland habitat indicator group was only 3 % of the total. This indicates the scarcity and largely fragmented distribution of unimproved calcareous grassland even in areas with suitable geology. The proportion of species was far higher in the neutral grassland group (38–45 %) and even the acid/moorland group (11–15 %).
The habitat indicator groups with the highest proportion of species in the lowland heath landscapes were heath generalist species (42 %) and acid or moorland species (27 %). Woodland species were also well represented (16 %).
In coastal landscapes, 35–43 % of the species fell into the neutral grassland species group, followed by weeds/alien species (16–17 %). Maritime species only accounted for 9–15 % of the total.
Additional analysis showed that distribution of characteristic vegetation types demonstrated differences between designated and non-designated areas, suggesting that larger areas of characteristic vegetation occurred in the designated sample squares (Hornung et al., 1997).
The datasets have been assigned digital object identifiers and users of the data must reference the data as Barr et al. (2017) and Bunce et al. (2017).
The datasets are available from the CEH Environmental Information Data Centre
Catalogue (
During recent decades there has been increasing concern over the loss of a number of valued landscapes and their associated characteristic habitats. A number of policies have been introduced to protect and enhance the remaining areas of these characteristic habitats. The UK biodiversity action plan (and the EU Habitats Directive) has also set targets for the protection of threatened species and habitats. However, overall, there is inadequate information with which to judge the status and quality of these and how they are changing at a national level. Together, the land cover and vegetation data described in the present paper provide an important baseline offering the potential for the monitoring and evaluation of threats to the landscapes and their characteristic habitats. The data also offer information useful for evaluating the quality and ecological characteristics of the surveyed landscape types in relation to a range of potential drivers.
It seems likely that further declines in ecological quality may have occurred since the survey bearing in mind current trends, but the extent of these could only be determined by a monitoring programme, for which this survey provides a useful framework. The Countryside Survey has demonstrated the robustness of a similar database for such a repeat.
According to the findings to date, it could be expected that changes are more likely in unprotected, undesignated land in the uplands than in protected, designated land in coastal, heath and calcareous grasslands. In general, previous analysis of these data has shown that the areas protected by legislation (designated) are of higher ecological quality than those in non-designated areas. This result could indicate that such designations may therefore provide protection for threatened habitats but it may also reflect the original designation of high-quality habitats. This is valuable information in the targeting of initiatives and funding designed to restore the given habitats.
The datasets provide a broadly defined distribution in England of four landscapes of interest including the broad habitats characteristic of the landscapes, as well as areas with potential for these habitats. These data form valuable contextual information for further specific surveys and monitoring. The datasets also provide an objective characterisation and quantification of the land cover and vegetation within the defined areas of these landscapes by field survey of a stratified random sample of 1 km squares within each landscape. The resultant data have been used to assess the distribution of species representative of the characteristic habitats and in the different sampling strata of the landscapes, and they offer much potential for further work.
The survey was the first time that a statistically rigorous assessment of
ecological quality has been attempted across such a wide range of
ecologically important habitats using similar methods and standardised
protocols at a national level. The standardised design of the survey offers
the opportunity for the possible integration with future monitoring surveys
of the status of the British countryside, as an element of the Countryside
Survey programme. The additional targeted 1 km sampling squares of the Key
Habitat Survey could be surveyed as an additional element within the
Countryside Survey field survey to add value and yield additional information
regarding the targeted landscapes in question, should resources allow. The
location of the vegetation plots have been permanently marked to facilitate
future resurvey and are thus able to be monitored over time and, as stated
above, would facilitate long-term ecological monitoring linked to a range of
drivers. Consideration should be given to the inclusion of these additional
targeted sites in the next full Countryside Survey in Britain, for which an
addition to the series is now overdue (the latest updates may be found at
CMW prepared the manuscript with contributions from all co-authors and is the current database manager for the Land Use Research Group at CEH Lancaster. The sampling framework and survey strategy was based on methods designed by RGHB, and the field survey was overseen by CJB.
The authors declare that they have no conflict of interest.
We thank all the land owners who kindly gave permission to survey their holdings in the survey sample squares in 1992 and 1993. Without their co-operation and assistance the Countryside Survey and related surveys would not exist. We also acknowledge and thank all the field surveyors involved in each field campaign (Henry Adams, Tanya Barden, Elizabeth Biron, Roger Cummins, John Davis, John Day, Richard Hewison, Gabby Levine, Amanda Marler, Elizabeth McDonnell, Karen Pollock, Sam Walters, Mike Webb). We thank Caroline Hallam for data management during the project in the 1990s. The survey was funded by the Department of the Environment (DOE) (now the Department for Environment, Food and Rural Affairs (DEFRA). We thank two anonymous reviewers whose comments have improved the manuscript considerably. Edited by: David Carlson Reviewed by: two anonymous referees