How To Set Effective, Evidence-Based Urban Tree Canopy Goals

Learn why urban tree canopy goals are powerful tools for urban forest management and how to set a goal that is both empirical and ambitious.

April 20, 2021  |  Alec Sabatini

urban tree canopy goals along a tree lined city street
Cities around the world are using tree canopy goals, usually in the form of percent tree canopy cover, to guide urban forest management and meaningfully improve the livability of their communities. Urban tree canopy (UTC) is ideal for goal setting because it can represent the complex distribution and benefits of an urban forest within a single metric.

Urban tree canopy goals must walk a careful line of ambition, inspiration, and practicality. To encourage well-informed canopy cover goals we have assembled some best practices to help communities find the right target for them.

“Many cities set goals — some based on careful study of current canopy, community needs, and availability of planting space. They follow the principle of “right tree, right place.” Others, based on the principle that more trees are better than fewer, set ambitious campaign goals, then work to mobilize efforts to meet it.”

-2014 Canopy Goals for US Cities, Vibrant Cities Lab

The Status of Urban Tree Canopies

 

Measuring, tracking, and improving urban tree canopies is an essential component of sustainable urban living. As the world’s population continues to urbanize the value of healthy UTC is only going up. Unfortunately, the global urban canopy trend is moving in the opposite direction. A worldwide analysis showed urban forest cover on average is slightly, but significantly decreasing.

The United States is also losing urban tree canopy, to the tune of 175,000 acres or 36 million trees a year. That represents a loss of $96 million in tree benefits a year, and those benefits, like heat reduction and public health improvements, are growing in necessity.

 

Urban tree canopies are in perpetual motion as growth and regeneration push against destructive forces, both natural and anthropogenic. These include development expansion, old age, disease, pests, and fire. Reversing this course starts with knowing the extent of the urban tree canopy and then establishing a goal for growth.

“By knowing the amount of and direction in which urban tree cover is moving, urban forest management plans can be developed to provide desired levels of urban tree cover and forest benefits for current and future generations.” (source)

 

Every Quantifiable Goal Needs a Baseline

 

Before setting a tree canopy cover goal, the current coverage must be understood via an Urban Tree Canopy assessment. There are multiple methods for completing a UTC assessment that vary in scope and output, such as point sampling and high-resolution land cover mapping.

An Urban Tree Canopy Assessment will quantify the extent or footprint of the urban forest, most commonly expressed as the percentage of a defined area. Depending on the assessment method, a UTC Assessment will also offer additional geospatial information, including other land cover percentages and possible planting areas (PPA).

 

Also, since most of the benefits of trees are causally linked to a healthy spread of leaves and branches, the canopy cover information can be used to create estimates of the ecosystem services provided by the urban forest.

For an example of all that UTC assessment can provide, check out PlanIt Geo’s UTC Assessment Report for the City of Colorado Springs. The assessment analyzed the City’s UTC and PPA at multiple geographic scales and compared imagery over a 20 year period to track canopy change. The findings showed tree canopy increased 3% from 1999 to reach a peak of 17% in 2015. The UTC was made up of an estimated 270,000 trees that are providing $198 million in benefits. This information was invaluable to the urban forest management planning process that followed.

Once you know the baseline canopy coverage, it is possible to start working on a future canopy cover goal. UTC assessment should be a periodic process and experts recommend they be conducted every 5 to 8 years to track canopy change, assess performance, and adapt priorities to changing needs and budgets.

Factors That Influence Urban Tree Canopy Goals

 

After you know what you have to work with, there is a wide variety of factors that are useful in setting an effective canopy goal. There is not one optimal percentage for urban tree canopy cover, but instead, each community must weigh the desired benefits against the costs of planting and maintaining the increase in canopy.

tree canopy goals are unique in a desert environment

Geographic Considerations

While not a hard limit, climate should be used to frame the goal-setting process. Global analysis shows the average urban tree cover in forested areas is 30%, 18% in grasslands, and just 12% in desert areas. This compilation of canopy cover goals provides a clear demonstration of the influence geography and climate can play on urban canopy targets.

Though every place has its own unique mix of population density, development, industry, climate, and forestry dreams, finding comparative communities that have completed a UTC assessment can also be a major help in establishing an informed canopy cover goal.

urban tree canopy goals on a private campus versus public land

Physical and Financial Possibilities

How many more trees are actually possible? Additionally, how much of the plantable land identified in the UTC assessment is public vs private? The answers to these questions can and should steer the canopy cover goal-setting process.

Funding availability will of course also dictate how much canopy growth is possible. Tree planting is only the beginning and any ambition of planting targets must be paired with equally ambitious tree management plans. Such considerations will help avoid an overly aggressive goal, which can lead to staff frustration, volunteer burnout, and funder fatigue.

urban tree canopy goals are unique to your local area

Local Challenges

What are issues in the community that can be positively influenced by increased urban tree canopy? This question should always be at the heart of setting a coverage goal, as it is the very purpose for the goal itself. Working backward from the desired outcomes of increased UTC will ensure the coverage goal is targeted on what matters most, be it lower downtown temperatures or improved access to greenspace.

Understanding the most pressing local issues is best done by supporting a UTC assessment with the engagement of a multitude of stakeholders. When Tacoma, Washington set its urban canopy growth goal of 30% by 2030, it supported the planning process with a robust research phase that included online surveys and public meetings to better understand community needs and interests.

Selecting A Percent Canopy Cover Goal

 

There are admittedly a ton of components to consider when setting a canopy cover goal. Luckily there are decision support tools that can simplify this process, such as TreePlotter™ CANOPY.

CANOPY integrates the information gathered from UTC assessments and tree inventories and creates easy-to-use visualizations of canopy distribution and planting space. CANOPY also includes functions that show how new plantings will address environmental or socioeconomic issues and test different planting scenarios.

Will it take 1,000 or 10,000 trees to make meaningful progress on the top municipal issues? Testing out different planting hypotheses with software can be a tremendous help in setting an evidence-based canopy cover goal. Through assumptions, a municipality can narrow down to a percent canopy cover that represents an aspirational but manageable amount of new plantings.

urban forestry consulting

A Canopy Cover Goal Is Just The Beginning

 

Establishing a canopy cover goal is usually the beginning of the process to define and adopt an official planting strategy that will be included in an urban forest management plan. It is a crucial first step though, and a tree canopy goal is a powerful tool. It helps prioritize forest management actions, motivate the public and officials, and inspire funding and stewardship.

 

“Tree planting should be methodically planned with a specific purpose in mind. The first step in developing a planting strategy is to define the goals.”

 

Chris Pieffer, Director of Urban Forestry Consulting Services, PlanIT GEO

A citywide canopy goal is important, but to be implemented it will need to be broken down into smaller functional targets, and supported with strategies in an urban forest management plan. An excellent example of this can be found in Appendix A of Tacoma’s Urban Forest Management Plan, which examines their canopy goal of 30% by 2030 and what it will take to get there. Specific growth goals are set for different geographic scales and planting priority was given to areas with lower than average canopy and income levels.

PlanIT Geo has TreePlotter™ Software Suite, purpose-built to make processes like setting urban canopy cover goals easier. We also have experts on hand to guide communities through understanding their urban forest in terms of what they have, what they want, and how to get there.

Supporting Urban Forests Around the World

 

PlanIT Geo specializes in supporting urban forest management with holistic solutions, including urban tree canopy assessments, management plans, tree inventories, and software that best serve your community’s needs and goals.

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Join Our Newsletter

Stay informed on the urban forestry industry with quarterly newsletters, live webinars, and industry-specific content delivered to your inbox.

Urban Forestry Webinars

PlanIT Geo has a substantial on-demand webinar library. Get CEU credits, grow your knowledge base, and stay current on cutting edge industry technology.

Follow Us

We love to share industry-related news, software tutorials, blogs, and company news across our social channels.