We support this policy and are pleased to see that it is worded in terms of outcomes (tree canopy cover) rather than inputs (e.g. number of trees planted).
We would like to see the policy require that best practices in the selection of tree species are followed, e.g. taking into account concerns such as maximising biodiversity benefits; ensuring resilience of the tree population to drought, disease, storm winds; avoiding problems such as allergen production or roots creating hazards, etc. [1]
We welcome the policy direction “provide sufficient space above and below ground for trees and other vegetation to mature”. The layout of tree planting and the amount of space given to each tree is an important determinant of tree survival - trees standing alone, and with limited space for root development or rainwater interception, are more susceptible to damage from wind or drought - as was seen at the Grafton Centre where many of the trees that were planted did not survive long.
We strongly support the fact that the first five bullet points are about “protecting” existing trees on a development site. We therefore caution that the qualification of “when felling proves necessary” will need very careful definition: felling should only be undertaken in exceptional circumstance (e.g when necessary for public safety or protecting property) and, if essential, should only be undertaken at a time of year when it does not damage wildlife such as nesting birds. A frequent cause of tree felling is shading of gardens and developers should be required to think long term about shade-casting when selecting tree species and planting locations.
[1] See for example https://www.forestresearch.gov.uk/tools-and-resources/fthr/urban-tree-manual/