There is no universally agreed definition of tree, urban forest, or urban forestry among practitioners. Definitions of urban forest range from the very broad that include all forms of vegetation growing anywhere within an urban environment to more focused definitions aligned with the usual understanding of forests as tree-dominated ecosystems. Some of the terminology used as part of this Urban Forest Management project may be unfamiliar to many people therefore, clear definitions should be articulated. For the purposes of Tacoma’s Urban Forest Management Plan, the following definitions have been adopted (derived from a variety of U.S. and international sources):

General Terms

Arboriculture is the branch of horticulture concerned with the cultivation, management and study of individual trees.

City-maintained land means freehold land that is owned by the City, State land vested in or managed by the City under a statutory order, and land that is leased by the City from an external party.

DBH, or Diameter at Breast Height, is a standard measurement of a tree’s size. It is measured at 4.5 feet above ground.

Ecosystem services provided by trees and the overall urban forest are generated as a result of healthy urban and rural forest ecosystems that serve as ecological life-support systems. Urban and rural forests provide a full suite of goods and services that are vital to human health and livelihood natural assets. Many of these goods and services are traditionally viewed as free benefits to society, or "public goods" - wildlife habitat and diversity, watershed services, carbon storage, and scenic landscapes, for example(3).

Forest means an area where the dominant vegetation comprises trees and large shrubs with a mature height of more than 10 feet.

Green infrastructure, for the purposes