Lowland grassland sites inventory v2.01 England
Description
This is a spatial dataset that describes the geographic extent and location of lowland grassland
habitats in England. It combines data from the Natural England BAP priority habitat inventories for
lowland calcareous grassland, lowland meadows, lowland dry-acid grassland, purple moor grass and
rush pasture and lowland meadows inventories with data from the undetermined grassland
inventory.
Purpose and Methods of data capture
The original grassland inventories were developed during the mid 1990s to document the known
localities of good quality species rich lowland grassland of nature conservation value in each English
county. These inventories highlighted only those grassland sites for which English Nature, or other
organisations, held detailed survey information at the time of their publication.
In 2004 English Nature published priority lowland grassland inventories, following re-interpretation
of the original survey data, in light of priority grassland definitions and improved digitisation of site
boundaries. These inventories also incorporated the data captured by local record centres as part of
the National Biodiversity Network South West Pilot.
The inventories never provided a comprehensive coverage of all lowland grassland of nature
conservation value and there exist significant gaps where survey information simply wasn’t available
in the 1990s. For example lowland calcareous grassland is thought to be relatively well covered in
the inventories because of the large scale surveys on chalk and limestone area undertaken by the
Nature Conservancy Council in the 1980s, whilst lowland dry acid grassland is known to be underrepresented due to a paucity of survey data at that time.
These latest inventories have been published as a result of the two year joint funded project
between English Nature (now part of Natural England) and the Department for Environment, Food
and Rural Affairs (Defra). This project set out to produce an up-to-date set of inventories which will
be used to:
•
effectively target of Higher Level Stewardship (HLS) options within Environmental
Stewardship, for which grassland is recognised as a priority by the UK Biodiversity Action Plan are a
key focus;
•
inform local and regional spatial planning, also contributing to delivery of the England
Biodiversity Strategy;
•
enable achievement of favourable conservation status for grasslands identified under Annex
1 of the Habitats Directive.
The project aimed to utilise recently collected grassland survey data of the requisite quality to
update the inventories region by region. It also captured informal knowledge of the existence (or
disappearance) of good species rich grassland sites by inviting local naturalists/groups, including
BSBI Vice-County recorders, to regionally held workshops.
Datasets were obtained and prioritised for further evaluation and capture according to currency and
degree to which survey classifications are aligned to BAP habitat definitions.
1
Survey Type
NVC
map
and
quadrats
NVC map only
Phase 1 and target
notes
Phase 1 map only
ESA/SSSI
site
description/ species
list
Air Photograph /
Landcover
Expert
knowledge
of
deterioration/
loss
1.1
Age of Survey
< 5 years
High (1)
5-10 years
Medium (2)
> 10 years
Medium (3)
Medium (2)
Medium (3)
Medium (3)
Medium (4)
Low (5)
Low (5)
Medium (4)
Medium (3)
Low (5)
Medium (3)
Low (6)
Medium (4)
Low (5)
Low (6)
Low (7)
High (1)
High (1)
High (1)
For the collated datasets, sites were assessed against BAP Priority Habitat definitions. Where
possible, all sites within priorities 1-4 were assessed, but in some cases resources only allowed
priority 3 and above to be assessed and captured.
For sites which met the required ecological definitions, habitat boundaries were captured from
existing GIS data files, or digitised from paper maps to defined standards, using OS MasterMap.
Aerial photographs were supplied to the contractors to aid identification of habitat boundaries. A
Habitat Data Capture Tool was also supplied to the contractors and used to attribute new or
modified sites by habitat and degree of confidence in interpretation and mapping.
On the basis of evaluated data, sites were added or removed from the inventories, or amended.
Sites were removed where they no longer existed as vegetated habitat, i.e. having being developed,
or due to strong evidence that grassland of priority habitat quality was no longer present. Sites on
the existing inventories were modified in terms of boundaries and/ or description based on more
recent or comprehensive data. Sites were added where supporting data met the required criteria
for confidence and was comprehensive enough to establish presence of priority habitat or good
quality semi-improved grassland (GQSIG), i.e. on the basis of the process undertaken to assess data
and map sites.
Attribution followed a rule-base, the qualifiers attached to inventory sites are:
•
Definitely is the named Priority Habitat/GQSIG
•
Priority Habitat/GQSIG definitely present within polygon but not mappable
•
Probably the priority grassland/GQSIG type but with some uncertainty over interpretation
(and mapping)
•
Probably priority grassland but some uncertainty over interpretation of type (and mapping)
•
Priority grassland/GQSIG may be present but data is insufficient to determine presence
confidently (or map accurately)
During the course of the data evaluation, contractors encountered situations requiring decisions not
covered by supplied guidance. In such instances contractors devised rules, in agreement with
Natural England project officers. These rules were incorporated into subsequent contract
specifications and guidance.
Data collation contracts were awarded to: West Midland’s local record centres, rECOrd (Cheshire),
Tullie House Museum (Cumbria), ADAS (Lancashire, Greater Manchester and Merseyside),
Northumbria Wildlife Trust (North East). Regional data capture contracts were awarded to: Just
Ecology (North East, North West and West Midlands), ADAS (East of England and East Midlands),
Yorkshire and Humber local record centres, South East and Greater London’s local record centres.
Survey data was sourced from a large number of sources including local authorities, wildlife trusts,
local record centres, National Trust, English Nature, Defra/RDS, Forestry Commission, National Parks,
utility companies and natural history societies.
Data quality
The lowland grassland inventories are considered to have a good level of completeness in terms of
coverage of priority grassland sites. Sites in the inventory will have been accurately identified,
though many sites may be mosaics with other habitats and scrub. In many cases polygons are
derived from the site boundary rather than the extent of the grassland stand itself. The original data
sources are often more than 10 years old.
The rate of grassland change over the last twenty years though means that many sites within the
inventory, particularly those with no recent information, may have lost their conservation interest as
result of agricultural intensification and changing land use. A sample survey of non-statutory
inventory sites found that only 28% of stands from polygons attributed as lowland calcareous
grassland were in favourable condition. A proportion of sites from the undetermined grassland
inventory will potentially meet the criteria for one or more of the priority grassland types.
Additional information sources
The individual inventories are available to download from the Natural England website:
http://www.gis.naturalengland.org.uk/