London's canopy is counted

London's canopy is counted

posted by Chris Hastie on Feb 21 2012 19:35

For the study the LTOA used the i-tree tools developed by the U.S. Forestry Service and its partners. They provide scientific tools to assess community trees and these are constantly being improved and developed. This particular set of tools - i-Tree Canopy - allows swift, desktop study using Google maps. The accuracy of the study depends on careful attention to detail when assessing the aerial map under scrutiny. Several members of the LTOA have carried out the study using a narrow range of unambiguous land cover types and several other members have verified the entries.

Calculating accurate figures for London’s tree cover is vital for the future:

  • The Mayor of London and the London Plan propose targets for increasing tree canopy by 5% before 2025 and a further 5% by 2050. Estimates normally include a Standard Error (SE) of such a size that it would be difficult to calculate such increases. The LTOA’s survey has an SE of only +/- 0.56%. From now on progress will be measureable.
  • Increasing London’s tree canopy is the key to a habitable city in the future, as not only global climate change but the more localised effects of the urban heat island make the city less of a place to live comfortably. Without knowing what we have now, we cannot realistically set goals. Are we succeeding or are we failing?
  • Google maps now present the possibility of using previous aerial photo surveys. With these surveys we are able to show the difference tree planting or development has made over the past years to London’s tree cover.
  • We know the size of London. Using these figures we can now make quantitative assessments of the need for for planting and show that targeted planting can make a difference.
  • We can finally start to plan London’s future Urban Forest.

For more information see the LTOA's website.

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