Summary
The NFI definition of woodland is a minimum area of 0.5 hectares under stands of trees with, or with the potential
to achieve, tree crown cover of more than 20% of the ground.
Areas of young trees, which have the potential to achieve a canopy cover of more than 20%, will also be
interpreted as woodland and mapped. The minimum width for woodland is 20 m, although where woodlands are
connected by a narrow neck of woodland less than 20 m wide, the break may be disregarded if less than 20 m in
extent.
Intervening land classes such as Roads - all 'tarmac' roads should be excluded from the woodland area, but
internal forest tracks, farmers tracks, rides etc. willbe included as part of the woodland if < 20m wide.
Rivers - where the gap in woodland is 20m then rivers will be excluded from the woodland area.
Power lines etc. - where the gap in woodland is 20m then power lines will be excluded from the woodland area.
Railways - all normal gauge railways should be excluded from woodland
Scrubby vegetation" is included within this survey where low woody growth seems to dominate a likely woodland
site.
The definition of an open area is any open area that is 20m wide and 0.5 ha in extent and is completely
surrounded by woodland.
The woodland boundaries have been interpreted from colour aerial orthophotographic imagery. For the base map,
photographic images aimed to be no older than 3 years at the time of mapping (i.e. areas mapped in 2007 would
be based on photographs that were ideally taken no earlier than 2004). As the map is be the basis for a longer
rolling programme of sample field surveys it has been necessary to develop procedures to update the map to the
date of the field survey, currently 2011, for the purpose of reporting on the current phase.
The map is continually updated on an annual basis. These updates will are achieved by a combination of remote
sensing and updated aerial imagery analysis for changes in the woodland structure and with reference to
available new planting information from grant schemes and the FE sub-compartment database.
Ordnance Survey MasterMap® (OSMM) features have been used as a reference for capturing the woodland
boundaries. OSMM is the most up to date large-scale digital map of GB providing a seamless database for
1:1250, 1:2500 and 1:10000 survey data.
All woodland (both urban and rural, regardless of ownership) which is 0.5ha or greater in extent, with the
expection of Assumed woodland or Low density areas that can be 0.1ha or greater in extend, as been mapped
Woodland that is less than 0.5ha in extent will not be described within the dataset but will be included in a
separate sample survey of small woodland and tree features.
Description.
The primary objective is to create a new digital map of all woodland in Great Britain using O.S.MasterMap
features as boundaries where appropriate. The map shows the extent of all woodland of 0.5 ha.Woodland
categories are defined by IFT (Interpreted Forest Type) values. Detailed Woodland categories are:
Broadleaved
Conifer
Felled
Ground Prepared for New Planting
Mixed - predominantly Broadleaved
Mixed - predominantly Conifer
Young Trees
Coppice
Coppice with Standards
Shrub Land
Uncertain
Cloud or Shadow
Low Density
Assumed woodland
Failed
Windthrow/Windblow
Non woodland categories are defined by the IOA (Interpreted Open Area) values. Detailed Non woodland
categories are:
Agriculture land
Bare area
Grass
Open water
Other vegetation
Power line
Quarry
River
Road
Urban
Windfarm
A full list of attributes can be found in the Data Lineage section.
Any maps produced using this data should contain the following Forestry Commission
acknowledgement: "Contains, or is based on, information supplied by the Forestry Commission. © Crown
copyright and database right [Year] Ordnance Survey [100021242]". Attribution statement: Contains OS data © Crown copyright [and database right] [year].