Tools and Resources
The Trees Outside Woodland (TOW) map is a project funded by the UK Government through Defra’s Natural Capital and Ecosystem Assessment programme (NCEA) to map trees above 3 metres and 5 m2 area outside of woodland, including small woods, groups of trees and lone trees in England.
Approximately 30% of tree cover in England exists outside of the National Forest Inventory (NFI) woodland map (Forestry Commission, 2017). The NFI contains only woodlands > 0.5 ha. This is the first time a national, free to use Trees Outside Woodland (TOW) map has been produced.
Trees outside woodland provide valuable ecosystem services such as habitat connectivity, carbon storage, and social and health benefits.
The Trees Outside Woodlands (TOW) map shows the location and extent of lone trees, groups of trees, and small woodlands based on aerial Lidar and satellite imagery. Each feature has information on height, area, and woodland type categorisation.
The map was derived from a range of datasets including the National Lidar Survey (Environment Agency (EA)), Vegetation Object Model (VOM) (EA), Sentinel-2 (European Space Agency) imagery and Ordnance Survey Mastermap. Forest Research’s National Forest Inventory woodland map is also a key input.
Trees are identified by spatial algorithms using vegetation indices derived from satellite imagery and height data from lidar datasets. The method identifies trees with a minimum height of 3 m but canopy delineation extends to a minimum of 2.5 m allowing the canopy of 3 m trees to be identified. Data from Mastermap were used to ensure infrastructure such as buildings and roads are removed.
Trees Outside Woodland are also being assessed at a more granular level as a natural capital asset through the Natural Capital Ecosystem Assessment (NCEA) strategic sample surveys. The TOW map will support NCEA tree surveys and government tree planting.
The TOW map is available under open government licence and free to download from the Forestry Commission open data download website (Forestry Commission) and view online on the NCEA ArcGIS Online web portal (Trees Outside Woodland).
A full report containing details on methodology, accuracy and user guide is also available at NCEA: National Trees Outside Woodland Map
The map and report is also available via open web services from Defra’s Data Services Platform (DSP).
For further information, please email remote.sensing@forestresearch.gov.uk.
