Uncovered
The removal of ground cover from, on or above the soil surface.

Understory Tree
An evergreen or deciduous tree whose mature height can be expected to range between 15 feet and 35 feet and which has an expected crown spread range between 15 feet and 25 feet as determined by the latest edition of “American Standards of Nursery Stock” as set forth by the American Association of Nurserymen.

Undisturbed Area
An area free of any tree disturbing activity except the planting of required landscaping and plantings required by conditional zoning requirements.

Unhealthy
A plant or tree that meets any one or more of the following:
1. Its foliage and bark have a form and color that is not characteristic of the species similarly located within the city;
2. Its twig elongation is dissimilar to that of others of the same species and size similarly located within the city;
3. It is not free from infestation of insects and detrimental diseases; 
4. More than 10% of its trunk circumference dies in any 1 calendar year;
5. More than 30% of its crown dies or is lost in any 1 calendar year; and/or
6. It no longer screens, filters or shades the area for which it was installed.

Unity of Development
The visual and functional integration of buildings within a development or area.

Urban Frontage
The following frontages: Green (-GR), Green Plus (-GP), Urban Limited (-UL), Urban General (-UG) and Shopfront (-SH).

Utility Service Area
An area which contains any utility box, booster box, switching station, transformer, pedestal or backflow preventor or similar above-grade device used to serve underground utilities.

Utility Service Plan
A plan associated with a Planned Development Master Plan that provides information for mail distribution and solid waste collection.