Forest 101
Natural Climate Solutions
Reimagining Our Cities
Carbon + Climate Change, Forest Management, Forest Products, Urban Forests

Urban Tree Canopy. AKA the urban forest from above.

What is it, why do we measure it, and why does it matter for climate goals?

Author: Alec Sabatini

Alec is the content writer at PlanIT Geo™, a global urban forestry consulting and software development firm, and develops educational content at the intersection of trees and technology. PlanIT Geo’s TreePlotter™ software suite is used worldwide by private tree care companies, governments, and nonprofits for tree inventories and asset management.


When people talk about urban forests or urban forestry, they mention urban tree canopy - and they mention it soon, and mention it often. I only lasted 12 words before typing it. Point proven? So, what exactly does it mean when we refer to urban tree canopy, and why are cities around the world so focused on tracking it?

For an individual tree, the canopy refers to the spread of leaves and branches. In the context of urban forestry, the term urban tree canopy refers to the collective canopies of all trees within a defined area, like the city limits. When viewing a city from above it essentially measures how much of that view is covered by green vs. gray assets, such as roads, buildings, or parking lots. There is a careful science to getting this measurement as accurate as possible, one that has been improving in leaps and bounds over the last 20 years.

Picking Plants Out Of Pixels

The process is called an urban tree canopy assessment. Imagery (either from satellites or plane flyovers) is run through a computer analysis to classify each pixel into certain categories. The categories can include tree canopy, non-canopy vegetation (grass, shrubs), open ground, impervious surfaces (buildings, roads), and water (ponds, rivers).

Then other geospatial datasets are blended in to further improve the accuracy. For the purpose of urban forest management, the final product is often simplified down into three types: where trees are, where trees could be, and where trees shouldn’t be (like impervious surfaces or sports fields). For example, an urban tree canopy for Washington, DC found the city was 37% tree canopy, 24% possible planting area, and 39% impervious surfaces

But wait! There’s still a couple layers left on this data onion. Thanks to the census and other surveys there is a ton of socioeconomic information tied to every block and neighborhood in the country. By overlaying tree canopy data on top of demographic data, urban foresters can identify significant trends, such as the disproportionate concentration of canopy in whiter, wealthier neighborhoods (a widespread pattern at the center of the tree equity movement) or the correlation between sparse trees and higher rates of asthma, heart disease, and skin cancer.

Why Measuring Tree Canopy Is So Helpful

There are three chief reasons tree canopy data is invaluable for cities.

  • Trees grow, and trees go, and we need to know.

Urban tree canopies are in perpetual motion. Tree growth and regeneration add canopy, while the destructive forces of development, disease, pests, and storms take it away. It’s hard to gauge from the ground, but taking a top-down view allows urban forest managers to track the change of canopy in every nook of the city, including both public and private lands. In fact, for most cities, the majority of their urban forests are on private residential land, so having this comprehensive perspective is vital.

 

  • Invest in the right trees in the right place, for max impact

Maps are a powerful storytelling tool. All of the data points from an urban tree canopy assessment can be combined into a clear, visual story on a map. Urban forest managers use software to map out tree canopy, and then mix in other metrics, such as available planting space and prevalence of urban heat, to develop a priority planting plan

 

  • Data rules. Back it up for the boss and the budget.

Urban forestry departments need to make the most of a limited budget, so it’s crucial to invest their available resources for new trees in the best possible areas.
Frequently, trees and landscaping are treated as an afterthought instead of an essential piece of the urban fabric. “Leadership within community forestry programs will always struggle to get outside agencies to buy into the value of trees without having canopy assessment data,” said Rob Davis, City Forester of Grand Junction, Colorado. Tree canopy data helps urban forest departments build buy-in from government leadership so they can justify their budgets, increase investment in tree planting, and upgrade city policies. Having maps and data that document exactly how tree cover is changing and how it is distributed across a city moves conversations into a discussion of reality instead of hypotheticals.

What’s Your Community’s Canopy Cover?

Find yourself a high vantage point, a plane or hot air balloon, or hop on Google Maps and take a look at your town from above. Try to make a rough estimate of how much of the view is covered by greenery. It’s worth checking to see if your community has completed an urban tree canopy assessment with a quick web search.

There is no magic number all cities should be seeking for canopy coverage. Climate, development pressures, and available space has a huge impact on existing tree canopy. Cities in the Southwest are often in the 5-15% range, while East Coast cities tend towards 30-40%. What is consistent is urban forests and their canopy are a key piece of the puzzle for addressing many of the top challenges facing cities today.

 

Reimagining Our Cities
Urban Forests

RECLAIMED | The Urban Wood Project

The Urban Wood Project began as a quest to reclaim wood from abandoned city homes. It very quickly became about so much more.

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Forest 101
Natural Climate Solutions
Reimagining Our Cities
Carbon + Climate Change, Forest Management, Forest Products, Urban Forests

Urban Forestry: The Need for Green Among The Gray

Communities need to balance economic, environmental, and climate goals.

Author: Alec Sabatini

Alec is the content writer at PlanIT Geo™, a global urban forestry consulting and software development firm, and develops educational content at the intersection of trees and technology. PlanIT Geo’s TreePlotter™ software suite is used worldwide by private tree care companies, governments, and nonprofits for tree inventories and asset management.


The positive impact urban trees and forests have on our cities and communities are not only becoming better understood, they’re becoming an essential part of our strategy to achieve meaningful climate goals.

In our previous post, we talked about the origins of Urban Forestry and why urban forests are so important to the health of our cities, communities, and climate. Now we’re going to go one step further and explore what actually goes into managing urban trees and forests and how communities are balancing economic, environmental, and climate goals.

How Communities Manage Urban Forests

The urban environment is a harsh place to thrive as a tree. Like us, the more stressed trees are, the more likely they are to get sick. Trees in urban spaces have a lot of stressors. They have to overcome limited root space, poor soil, heat, and pollution, flood and drought, and lost cat signs nailed to them at 2am.

Yet, there is perhaps an even greater threat to urban forests: development.

Space is always a hot commodity in cities. New housing projects or highway expansions are rarely possible without uprooting some trees, if not whole swaths of forest. (We call this the WUI  (woo-wee) or the “Wildland Urban Interface '' where wild lands meet urban.) Land conversion via development is one of the leading causes of deforestation - the permanent clearing of forested land for a new purpose.

In spite of these challenges, urban forests must be maintained, protected, and expanded if they are going to offer vital benefits to communities.

Pulling that off requires careful planning and a skilled workforce. Urban forestry is a multidisciplinary field with professionals in the public, private, and nonprofit sectors. The U.S. urban forestry industry employs over 500,000 people, including municipal and commercial arborists, municipal and utility foresters, environmental policymakers, city planners, consultants, educators, researchers, and community organizers.

Fundamentally, the work of urban forest managers is to monitor the urban forest and then evolve their plans and take action based on that feedback. There are two main methods of monitoring the urban forest, one from the bottom up, the other from the top down:

  • A tree inventory is completed on the ground by arborists who assess individual trees on a set of criteria and plot their location.
  • An urban tree canopy (UTC) assessment measures a community’s tree canopy cover through the analysis of aerial and/or satellite imagery and other geospatial data.

Communities use this information to guide their actions through long-range plans, such as an urban forest management plan (see an example plan). These plans create a framework for asking what kind of urban forest a community wants to see and envisioning the actions, goals, policies, and metrics to get there. It’s also an opportunity to collect input from many diverse stakeholders (city staff, elected officials, and the community) to develop a shared vision for the future.

With a plan in hand, it’s time for action. Urban forest management is part proactive and part reactive. Urban forest managers can plan out tree plantings, removals, and schedule maintenance, but they will also have to contend with unexpected events, such as storms and pest outbreaks, that require emergency action. These are usually initiated by requests from the public, and an urban forestry program may receive hundreds to thousands of requests every year!

 

A Green Commitment Worth Keeping

It takes committed professionals, frequently updated data, and evolving plans to support a healthy urban forest. It can be a daunting task, but there are tremendous rewards when done successfully. Unfortunately, a nationwide analysis found 36 million urban trees are removed annually, equating to a loss of $96 million in ecosystem services.

We should not have to pick between living in an urban area or having access to green space. Climate change, and the increasing stress it puts on cities, is only raising the need for healthy, equitably distributed urban forests. Integrating trees, along with other green infrastructure, into our communities is a solution that supports both people and the planet.

How to get involved with your local urban forest

If you would like to support your local urban forest, there are often ample local volunteer opportunities. Try a quick Google search to see if your community has a tree board, forestry-focused nonprofit, or a tree planting event near you and join their next volunteer event. Take a selfie with your tree and tree friends + tag it #forestproud.

Reimagining Our Cities
Urban Forests

RECLAIMED | The Urban Wood Project

The Urban Wood Project began as a quest to reclaim wood from abandoned city homes. It very quickly became about so much more.

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Forest 101
Natural Climate Solutions
Reimagining Our Cities
Carbon + Climate Change, Forest Management, Forest Products, Urban Forests

Urban Forestry: An Origin Story

Managing an urban forest is complicated! Why? Read on.

Author: Alec Sabatini

Alec is the content writer at PlanIT Geo™, a global urban forestry consulting and software development firm, and develops educational content at the intersection of trees and technology. PlanIT Geo’s TreePlotter™ software suite is used worldwide by private tree care companies, governments, and nonprofits for tree inventories and asset management.


To answer the question “what is forestry?'' we need to go back - way back - to the 1800’s when forestry first emerged on the scene as a profession. The goal then - much like it is today - is to manage for the current and future health of forests, and strive to ensure that forest benefits will be available for future generations.

Urban forestry on the other hand would take another 150 years before it was recognized as a distinct practice within the larger forestry family. Believe it or not, there are a lot of differences in managing rural trees and wilderness forests vs those in bustling downtown parks or along crowded streets.

The growing cities and urban sprawl of the 1960’s and 70’s proved to be the tipping point and marks the birth of urban forestry. Its focus was on setting new objectives, identifying new personnel, and implementing new management strategies to steward forests in the built environment.

What Is An Urban Forest?

Every tree in this photo is part of the urban forest!

 

The urban forest encompasses any tree, on public and private land, that lives where we do, from a small town to a crowded metropolis. It includes the trees that line our streets, shade our parks, and fill our backyards. It also includes dense, more natural stands of trees near our communities, such as nature preserves, river corridors, wetlands, and greenways.

One-third of U.S. land is forested and 18% of that land, about 141 million acres, is considered urban forest. 80% of the U.S. population lives in urban areas so the actions of urban forest managers have a profound effect on where people live, work, and play. If you want to have a direct impact on the well-being of your community, working in urban forestry is one way to do it.

Why Are Urban Forests So Important?

Like storm drains, street lights, and sidewalks, the urban forest is an essential part of our city – and our climate - infrastructure. Trees create a host of meaningful, measurable benefits. Collectively known as “ecosystem services”, trees and urban forests are critical to making our cities livable and sustainable.

A full list of urban forest ecosystem services runs quite long, but here are some of the essential benefits:

  • Carbon Sequestration & Storage

A healthy tree canopy pulls carbon dioxide from the air (sequestration) and stores it in roots, trunks, leaves, and soil (storage). Just like products made from rural forests, products made from urban forests continue to store that carbon for the life of the product. Urban forests are just starting to catch up to their traditional forest counterparts in efforts to track and reward this function through carbon credit and offset programs.

  • Cooling Our Cities

Trees are on the front lines of the battle against extreme urban heat, which as of 2022 is the number one cause of weather-related deaths in the U.S. Trees can drastically lower surface and air and surface temperatures through shade and evapotranspiration (the exchange of water with air).

  • Better Air Quality

Trees are sometimes known as the lungs of a city, but they can act as the liver too. Urban forests can remove tons (not metaphorically, literally thousands of pounds) of air pollution every year by absorbing gasses through leaves and trapping particulates out of the air.

  • Water Quality and Stormwater Control

Trees improve water quality and support stormwater management through rainfall interception and infiltration (water absorbed by the soil). Stormwater infrastructure is not cheap. Cities, especially those with combined sewer systems, are turning to trees and urban forests as an effective, affordable answer to handle heavy rains as seen through the installation of rain gardens and bioswales.

  • Improved Mental and Physical Health

Trees support physical health via improved air, water, and urban temperatures, but they also offer well-evidenced mental health support. Having easy access to trees or even views of trees helps reduce stress and enhance our well-being. The COVID pandemic made this connection especially clear.

 

Which sidewalk would you prefer to walk down?

 

Simply put, our cities, communities, and climate are better with trees around. Thanks to decades of research, we’ve become quite skilled at quantifying the benefits created by a single tree or an entire urban forest.

You can try it right now and get a benefit estimate for a tree in front of your home using the free MyTree tool. Urban forest managers often use software to estimate and track this information because it's invaluable for helping government leaders and community members accurately value the services provided by their urban trees.

 

Reimagining Cities Illustration
Reimagining Our Cities
Biomass + Renewable Energy, Carbon + Climate Change, Careers, Cities, Forest Management, Innovation, Mass Timber, People, Products, Urban Forests

FORESTS: Reimagining Our Cities

For the first time in history, more than 50 percent of the world’s population lives in a city.

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