You can help to protect your local trees from damage. If you see contractors digging near trees, PLEASE take a look in the trench to ensure they are not damaging the tree roots. If you see damage taking place then a photo or two would be useful for recording purposes. All utility contractors should be following the nationally recognised document designed to limit damage and protect trees during work. NJUG Guidelines for the Planning, Installation and Maintenance of Utility Apparatus in Proximity to Trees VOLUME 4 issue 2 2007. Link: http://www.njug.org.uk/publications/.
Other contractors working near trees should work to British Standard 5837 2012 Trees in relation to design, demolition and construction. Recommended links http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030213642
If you see private trees being damaged report the damage to their owners.
Trees within conservation areas are all protected and many others are protected with Tree Preservation Orders which can be viewed on the councils maps by adding the relevant named layers including Trees, TPO areas, Tree Preservation Orders and conservation areas: https://www.york.gov.uk/planning-applications/tree-works-planning-applications/1
If you see public or protected trees being damaged please report to the Local Authority. Link:https://www.york.gov.uk/contactus