Bristol Tree Canopy Cover Survey 2018 : display       About

Region details

Double-click on a region for data

Background

This Tree Canopy Cover (TCC) data is based on our work with i-Tree Canopy. This tool uses Google Earth imagery and allows the user to select a number of random sample points in a pre-defined region, in this case a Bristol Ward. If a sample point falls on any tree canopy it is defined 'tree', otherwise it is defined as 'non-tree' . Once enough sample points have been collected, it is possible to estimate the percentage TCC for the region.
The TCC estimates in this analysis are the work of Mark Ashdown, Chair of Bristol Tree Forum based on Google Earth imagery of April 2018. Forestry Research are compiling TCC data from across the UK and it is mapped here.
The prediction of environmental impacts from only an estimate of the tree canopy area uses US-based factors so is not calibrated for UK conditions. In that context, there is considerable uncertainly in extrapolating the data to the UK. The factors are shown below but the computed values derived from them must be treated with great scepticism because of this.
Estimates of the monetary benefits of those impacts is also subject to debate. The values shown below are based on those suggested by Forestry Research which uses figures from the UK government Air Quality: economic analysis. The figures have wide ranges of sensitivity.

i-Tree Eco

The recent i-Tree Eco survey arrived at a much lower overall estimate of TCC than the i-Tree Canopy method has provided, with an overall figure of 11.9%. The data for each region includes the pro-rated i-Tree Eco value.

Conversion factors and benefit values used

Component description kg/m2/yr £ per tonne
CO Carbon monoxide 0.101 0
NO2 Nitrogen dioxide 0.551 14646
O3 Ozone 5.489 0
PM10 Particulate Matter 2.5 to 10 microns 1.838 33713
PM2.5 Particulate Matter < 2.5 microns 0.267 0
SO2 Sulphur dioxide 0.347 1956
CO2 sequestered Carbon dioxide sequestered 1117.576 60
CO2 stored Carbon dioxide stored 28177.63 60
O2 Oxygen production 3017.45 0
Estimated number of trees / hectare @ 2.5m radius   : 250

Deprivation Score

The Deprivation score for wards is based on 2015 data from Bristol City Council by postcode. It has been re-aggregated for the current ward boundaries. The lower the score, the higher the level of deprivation.

A Trees of Bristol production supported by Bristol Tree Forum production. Code and data on GitHub.