The National Association of Tree Officers (NATO) was established in 1997, set up to serve the needs of local authority tree officers nationally.  Its principal aim was to promote and enhance the good management and care of the UK treescape through the Local Authority arboricultural function. As a UK based national organisation it represented the views and concerns of Tree Officers nationwide, with its membership open to all local authorities.

Due to the financial difficulties facing public sector services in recent years, it was decided in 2018 that NATO would work with the London Tree Officers Association (LTOA) to build a stronger national organisation. The LTOA remains the regional London tree officer group, and during 2018/19, the new NATO Directors have been working hard to restructure NATO, with a re-launch planned for early 2020. The new organisation will represent and promote UK tree officers at a national and international level and support the work of the regional tree officer groups.

In Spring 2020 the organisation relaunched as the Association of Tree Officers.