Urban Canopy Cover

Evidence shows that the negative impacts upon human health of urbanisation, such as increased exposure to heat stress and elevated levels of air pollution, are in part caused by the removal of vegetation relative to rural environments. Consequently, trees and the wider green infrastructure of a city are advocated as a cost-effective sustainable remedy. Trees also contribute to human well-being by softening the urban aesthetic and offering a focal point for human social interaction. Within the UK, there is a knowledge gap with respect to the numbers of trees in towns and cities. Anecdotal evidence for England and research from Wales suggests that tree numbers and therefore canopy cover is falling. City-wide tree canopy cover is a useful indicator of the extent of tree presence across a city. Its assessment can be simple, fast and highly reproducibly. Repeat observation could be a cost-effective means of monitoring tree populations, setting targets and tracking effectiveness of planting programmes. Presenting the canopy cover of 283 towns and cities of England this report provides a landmark baselining of England’s urban canopy. With reference to Scottish, Welsh and international cities a minimum canopy cover target of 20% for UK towns and cities (15% for coastal locations) is then recommended. The study used the ‘random-point method’ and includes reflections on this methodology in comparison to area-based approaches, associated errors and their implications in setting (and monitoring changes towards) future urban canopy cover targets.