Table 1.

Criteria for urban forest sustainability. Each criterion includes four levels of performance towards attaining the key objective (Clark et al. 1997).

Component	Criteria	Key objective
Vegetation Resource	Canopy cover	Achieve climate-appropriate degree of tree canopy communitywide.
	Age distribution of trees in community	Provide for uneven age distribution.
	Species mix	Provide for species diversity.
	Native vegetation	Preserve and manage regional biodiversity. Maintain the biological integrity of native remnant forests. Maintain wildlife corridors to and from the city.
Community Framework	Public agency cooperation	Ensure all city departments operate with common goals and objectives.
	Involvement of large private and	Large private landholders embrace citywide
	institutional landholders	goals and objectives through specific resource management plans.
	Green industry cooperation	The green industry operates with high professional standards and commits to citywide goals and objectives.
	Neighborhood action	At the neighborhood level, citizens understand and participate in urban forest management.
	Citizen-government-business interaction	Ail constituencies in the community interact for the benefit of the urban forest.
	General awareness of trees as community resource	The general public understands the value of trees to the community.
	Regional cooperation	Provide for cooperation and interaction among neighboring communities and regional groups.
Resource Management	Citywide management	Develop and implement a management plan for trees and forests on public and private property.
	Citywide funding	Develop and maintain adequate funding to implement a citywide management plan.
	City staffing	Employ and train adequate staff to implement citywide management plan.
	Assessment tools	Develop methods to collect information about the urban forest on a routine basis.
	Protection of existing trees	Conserve existing resources, planted and natural, to ensure maximum function.
	Species and site selection	Provide guidelines and specifications for species use, on a context-defined basis.
	Standards for tree care	Adopt and adhere to professional standards for tree care.
	Citizen safety	Maximize public safety with respect to trees.
	Recycling	Create a closed system for tree waste.