Increase Canopy Cover by Planting and Maintaining Trees

Photo © The Nature Conservancy (Kent Mason)

Tree canopy is the layer of leaves, branches, and stems of trees that cover the ground when viewed from above. Each species of tree has its own unique shape, size, and color, but all of them contribute to the overall tree canopy–benefiting wildlife and people, alike.

The Nature Conservancy staff, Rob Riccardo, Betty Chung, and Lauren Miura walking in Brooklyn Bridge Park, New York.

Photo © The Nature Conservancy (Kevin Arnold)

Some of the benefits that trees and their canopy provide to humans include, producing oxygen, cleaning drinking water, saving energy, reducing crime, and increasing property values. After one of the hottest, muggiest summers on record in North America, some of these, cooler temperatures and cleaner air in particular, might be very appealing to some of you out there.


Photo © Chang'r

Above is the great city of Los Angeles, California and, no that is not fog, but smog–a type of air pollutant consisting of particulate coal, vehicular and industrial emissions, and smoke. This smog can be harmful to humans and wildlife. Many cities experience air pollution like smog; and, with increasing temperatures amplified by the urban heat island effect, the poor air quality days are increasing in frequency and length.

Asthma and Air Quality


Photo © Mike Licht

Asthma is a chronic (usually long-term) lung disease that inflames and narrows respiratory airways. It can cause recurring wheezing, chest tightness, shortness of breath, and coughing. The exact cause of asthma is unknown but there are thoughts to be links to heredity, certain respiratory illness and viral infections. Exposure to irritants in childhood may also explain some cases of asthma. Over 25 million people in the U.S. suffer from asthma including seven million children. One of the irritants that can trigger an asthma attack is poor air quality, which is found in many cities in the United States.

“Forests are the lungs of our land. Franklin D. Roosevelt

Brooklyn Bridge Park looking towards Manhattan.

Photo © The Nature Conservancy (Kevin Arnold)

Trees are unique in that they rely on carbon dioxide to produce sugars for growth and release oxygen as a by-product. As trees take-in carbon dioxide they also absorb other gaseous chemicals in the air like ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide. Trees can store these gaseous pollutants in intercellular spaces reducing the pollutants found in the air we breathe. Particulate pollutants are captured on surfaces of the leaves and bark retaining them on the surface and effectively removing them from the air (although these can be washed off by rainwater). A large, healthy tree and its canopy removes almost 70 times more air pollution each year than a small or newly-planted tree with a smaller canopy.

Central Park in Louisville, Kentucky.

Photo © The Nature Conservancy (Devan King)

Trees specialize in shade. The larger and more contiguous the tree canopy the larger the shaded area and resulting cooling effects. Trees help reduce summer heat both by providing shade and through evapotranspiration. The right tree placed around a building can reduce air conditioning needs by 30 percent and peak summer temperatures 2-9oF. Street trees with canopies shade the asphalt and cement reducing the amount of heat that is absorbed or reflected by these surfaces. Evapotranspiration occurs naturally as water (one of the by-products of photosynthesis, along with oxygen) is released from the tree through little openings on leaves called stomates and evaporates in the heat, cooling the air around the tree.

In coordination with generous sponsorships from UPS, The Nature Conservancy, Brown-Forman, and Brightside planted trees for a community-wide planting day in West Louisville, Kentucky.

Photo © The Nature Conservancy (Devan King)

“Someone is sitting in the shade today because someone planted a tree a long time ago. Warren Buffett

Increasing the tree canopy on your property, at an office, or school is an easy, family or community event that can be relatively inexpensive. Most cities and some counties are supportive of increasing tree canopy and provide incentive programs. Use our local resources tool to find and contact your local extension office for more details on the incentive programs in your area. Other cheap options for increasing canopy cover include attending spring and fall plant sales hosted by most nurseries and plantations or memberships to organizations focused on increasing tree canopy, monitoring, and health, like Plant a Billion, Healthy Trees Healthy Cities, Arbor Day Foundation or the National Wildlife Federation.

How to map and size your trees


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Sign-on to Habitat Network and navigate to your sites via the Site Explorer. To add a tree, use the Tool Shed’s 3rd step, to add an object.


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We provide 3 different visual objects for trees, but they are all the same. Choose the one that best suits your preference and then click on the map where the tree is located on the property. You can use the vertices to click, drag, and size the tree to represent the canopy cover provided. Correctly sizing the tree will provide more accurate data for scientists to use when assessing canopy cover. Each tree species has a different environmental impact. Some trees have large canopies and provide more shade than others. Knowing the species of tree helps to provide accurate data for scientists. To set the tree species for the tree added, click on the “info” button found in the overview panel.


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The info panel will open and you can use the navigation bar on the left to fill in information regarding your tree.


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If the property being mapped includes a forested area, instead of adding each tree individually, you can use the tool shed’s 2nd step and add a habitat feature “forest” to map this area. Please remember to use the info button for the forest feature to fill in the important details regarding the forest being mapped, again this will provide important data to scientist.