Urban Tree Canopy (UTC) Assessment
Why are Trees Important Anyway?
We all know the story - trees produce oxygen, sequester carbon dioxide, provide us with shade, cool the air, provide habitat for wildlife, improve our air and water quality and mitigate our storm water, among other things. But recent studies show trees in our urban setting may be more important than we thought. Did you know that trees can actually help you reduce your utility bills? Or that trees in an urban setting can actually improve your health and state of mind?
With all of these benefits in mind, many cities are setting ambitious tree planting and conservation goals. One of the tools they're using is called an Urban Tree Canopy (UTC) assessment.
What is a UTC Assessment?
How much tree canopy do I have? How much tree canopy could I have?
According to Jarlath O'Neil-Dunne, of the University of Vermont, "The goal of the UTC assessment is to provide decision makers with detailed metrics on the state of their urban forest. These metrics enable decision makers to not only understand the urban forest in its current form, but to plan feasible approaches to increasing UTC."
Ideally, a UTC study should outline an area's Existing, Possible and Potential tree canopy.
Animation showing the steps to a UTC analysis - imagery, existing, possible, potential
For even more information, visit the US Forest Service site on UTC.
Why Use It?
UTC studies have been used for many different applications, including:- Urban Planning
- Establishing a tree canopy baseline and goals
- Asset management
Chicago, IL (RFP Mapping LLC)
Dallas, TX (RFP Mapping LLC partner, NCDC Imaging)
How Does it Work?
A UTC analysis is usually based on remotely sensed data, like high-resolution satellite imagery. Once that data is collected, the process follows a few basic steps:- First, turn your remotely-sensed data into something more useful and easier to manage. In this case, we generate 7-class land cover data.
- Second, use that land cover data to establish a baseline. This step answers the question, "how much tree canopy do we have?"
- Third, use the remaining land cover data to determine the possible tree planting area. These are areas that are biophysically suitable for planting a tree. Essentially, these are any areas not already covered by trees, hard surfaces, or water.
- Fourth, incorporate existing ancillary GIS data, like streets, zoning, and important ordinances that determine where trees can and can't be planted. This steps takes our lump sum possible area and and turns it into a potential area by carving out a more precisely defined tree planting area.
- Fifth, use your final potential planting area to determine how many individual trees, within a sepcified range of sizes, can be planted in your city or area of interest.