A detailed digital map of tree canopy cover is helping Central Bedfordshire Council gain an understanding of how many trees are on land under control of the Council’s Housing Department. A study, undertaken by specialist consultancy company Landscape Planning Ltd, compared the Bluesky National Tree Map data with layers from the Council’s Geographical Information System (GIS). Specialist scripts were developed in order to identify Council Owned Dwellings and Land Holdings requiring a visit for tree surveys as well as the number of trees at each location. Central Bedfordshire Council commissioned the project to inform a Competitive Tender.
“The first challenge we had to overcome was converting the Council’s Owned Dwellings data set from a series of points to polygons representing property boundaries,” commented Oisin Kelly, Principal Consultant at Landscape Planning Ltd. “A GIS script allowed us to process this data in just two days identifying just over 5,000 properties. In addition we looked at nearly 3,000 further parcels of land as part of the scoping exercise.”
“By using Bluesky’s National Tree Map data we were able to overcome many potential issues associated with the use of just aerial photographs,” continued Kelly. “Because the NTM has been created to a set of quantitative criteria it means the scoping exercise we undertook is repeatable. This gives us justification for its use as well as accountability and traceability for the full project methodology.”
The Landscape Planning team identified through the use of GIS analysis 5,177 Central Bedfordshire Council Owned Dwellings. In addition the scoping project considered 352 Land Holdings containing Owned Dwellings and a further 2,446 Land Holdings not containing Owned Dwellings. By comparing the Council data with Bluesky’s National Tree Map Landscape Planning were able to identify 2,985 dwellings containing trees. By excluding some trees based on size this figure was reduced to 2,058 dwellings containing 2,101 trees of 6 metres or taller.
“The Scoping Survey undertaken by Landscape Planning has informed us of the number of trees we have, of what size, and where,” added Steve Glazebrook, Consultant to Central Bedfordshire Council. “Based on these results we have been able to screen out many properties from our upcoming survey of trees in tenants’ gardens, providing significant cost savings.”
The National Tree Map has been created from the most up to date, high resolution aerial photography, colour infrared data and detailed height models. It includes three individual map layers, detailing more than 280 million trees with a canopy cover in the region of 20,000 square kilometres – around 13.5 per cent of land cover! Bluesky’s National Tree Map is already in use in a number of Local Authorities, commercial organisations and academic institutions with interest also being shown from Central Government agencies and utility companies.