New publication uses tree canopy cover percentage (TCC) to quantify urban tree cover
Question – What do Rhyl and Porthcawl have in common beyond being towns situated at the extremities of Wales?
Answer – They are both named among the five electoral wards within the UK for ‘least percentage urban tree canopy cover (TCC)’
A canopy cover Webmap of the UK’s towns and cities
The latest issue of the Arboricultural Journal (Vol 45, Issue 4, December 2023) recently published a paper titled, ‘The canopy cover Webmap of the United Kingdom’s towns and cities’ that discusses urban tree cover in Wales. The authors, Sales et al from The Office for National Statistics and Forest Research, summarise a citizen science assessment of the tree canopy cover (TCC) of the UK’s 5,749 urban wards.
In the publication, the authors presents data showing that Rhyl West and Porthcawl have some of the lowest urban tree canopy cover in the UK.
John Sweeny, Woodknowledge Wales stated, “At a time when local authority budgets are constrained, and some are removing street trees and hard-paving over the former tree site, I think we should be promoting not just timber as an industrial material, but also the importance of trees for our increasing urban populations.”
What is tree canopy cover percentage (TCC)?
Tree canopy cover percentage (TCC) is, according to the paper, ‘a two-dimensional metric indicating the area of leaves, branches, and stems of trees viewed from above across a given area, regardless of what other land-cover classes may lie underneath.’
As the authors note, this metric is an easily accessible measure and many independent urban TCC studies exist at local scales. Additionally, urban forests metrics can be derived from newly available datasets. However, results from these sources were limited. So, this research project set out to supplement this data through surveys carried out by citizen scientists using the i-Tree Canopy tool (https://canopy.itreetools.org/).
Trees as ecosystem services
Trees planted in urban areas, along transport routes and waterways, and in amenity areas can cost-effectively and sustainably provide the following ecosystem services:
- Decrease in airborne pollutants.
- Reduction of stormwater risk.
- Mitigation of extreme temperatures.
- Improvements to biodiversity.
- Improvements to human health (Doctor Green effect).
Tree canopy coverage in Wales
Results are of value in national and local strategy and management of urban tree planting. Highlighting substantial geographical variance, the data also demonstrates that fewer than one third of urban wards covered in the report had more than 20% tree canopy cover, a target previously recommended as a minimum for UK towns. [1] This figure drops to fewer than one fifth for Wales.
Sweeny explains, “This paper tells us that just over a fifth of urban areas (22.7%) in Wales reach this target. However, for some outliers such as Rhyl West and Porthcawl, tree canopy coverage is only 0.3%. The authors discuss the association of social vulnerability and low green infrastructure. Low canopy cover is unlikely to be the cause of deprivation or vice versa, but the link is likely to reflect financial investment and property values.”
References
- Kris Sales, Hannah Walker, Kate Sparrow, Phillip Handley, Madalena Vaz Monteiro, Kathryn L. Hand, Annabel Buckland, Alexander Chambers-Ostler & Kieron J. Doick (2023) The canopy cover Webmap of the United Kingdom’s towns and cities, Arboricultural Journal, 45:4, 258-289, DOI: 10.1080/03071375.2023.2233864
- Doick, K. J., Davies, H. J., Moss, J., Coventry, R., Handley, P., Vaz Monteiro, M., & Simpkin, P. (2017). The canopy cover of England’s towns and cities. TPBEIII Conference. Institute of Chartered Foresters. https://www.charteredforesters.org/resource/doick-et-al-the-canopy-cover-of-englands-towns-and-cities-research-paper
