Tree Preservation & Protection

Pursuant to Local Law 148 of 2023, NYC aims to achieve 30% overall tree canopy coverage by 2035. While planting new trees is crucial, preserving existing tree canopy is even more significant. Mature trees must be preserved during construction whenever feasible, as they provide greater benefits compared to newly planted replacement trees. Preservation can be complex and should be guided by Parks and a consulting arborist (CA) throughout the project. The following provides general guidelines for designing with tree preservation in mind.

Parks is expanding existing tree beds throughout the city to promote tree health and reduce potential trip hazards created by heaving: Devoe Street, Brooklyn (Credit: Parks)

Reconfiguration of a sidewalk to promote tree health (before and after): Aberdeen Road, Queens (Credit: Parks)

Under Section 18-107 of the Administrative Code of the City of New York and Chapter 5 of Title 56 of the Rules and Regulations of the City of New York, all construction work impacting trees within the public ROW must be approved and permitted by Parks. In addition, construction work must follow NYC Parks Tree Preservation Protocols, including appropriate Tree Protection Details, and NYC Parks Forestry Protocol for Planned and Emergency Utility Work. Ultimately, if the removal of a healthy tree is necessary, it must be approved and permitted by Parks, and tree replacement will be required based on a valuation of the trees impacted. This typically involves planting new trees within the project area or paying a fee to cover the cost of Parks planting the necessary replacement trees.

To preserve existing trees, their roots must be protected. Tree roots extend well beyond the visible canopy and are generally within the top three feet of soil. The critical root zone (CRZ) is the minimum area of roots a tree needs and will be determined by the CA using the International Society of Arboriculture’s Best Management Practices for Managing Trees During Construction, 3^rd Edition (F. Kite, T. Smiley, 2023). The individual CRZ radii should be incorporated into all phases of design and reflected on a CRZ map. The goal is to preserve as many roots as possible beyond the CRZ through sensitive design and the use of best practices during construction.

Tree Protection Area & Critical Root Zone Diagrams [PDF]

The Tree Protection Area and Critical Root Zone diagrams provide guidance for tree protection during urban construction projects.

The tree protection area (TPA) is the most important tool used in the preservation of existing trees. Generally, the TPA is developed in coordination with the CA during design and is defined by the canopy drip line of the tree. The TPA will always encompass the CRZ. During construction, the TPA is typically established with a fence or barrier, with installation of thick sawdust, plywood sheets or metal panels beyond the barrier, if necessary, to further protect spreading roots. In circumstances where a majority of roots are growing beneath pavement, special methods should be utilized. The contractor will be responsible for the care of protected trees during construction. No activity, including non-construction related activities, may occur within the TPA without approval from Parks and supervision by the CA. If construction work must occur within the TPA, the contractor must work with the CA to employ techniques, such as pneumatic excavation (air spading) to expose and preserve the roots in good condition. All work within the TPA must be completed by hand.