UrbanCrowns and ForestCrowns

Tools to assess tree crowns and forest canopies

by Zoё Hoyle, SRS Science Communications  • 
Illustration showing how UrbanCrowns determines crown volume using a single view of the tree. Illustration by U.S. Forest Service.
Illustration showing how UrbanCrowns determines crown volume using a single view of the tree. Illustration by USFS.

Yesterday’s article covered a method of estimating the stormwater function of urban trees using forest canopy measures. Just how does a manager or other practitioner calculate the extent of a tree crown or a forest stand canopy?

U.S. Forest Service scientists from the Southern Research Station Utilization of Southern Forest Resources unit have developed software tools that managers and others can use to easily assess the extent of urban tree and forest stand crowns and monitor the health of trees in urban and nonurban settings.

UrbanCrowns is a software tool designed to assist urban foresters, arborists, and community volunteers with assessing and monitoring urban tree crowns. The program analyzes a single, side-view digital photograph of a tree and computes the following crown metrics: height, diameter, ratio, volume, density, and transparency. Potential uses of the UrbanCrowns program include monitoring individual tree growth over time, detecting disease or insect damage in early stages, and providing data to quantify tree benefits such as carbon sequestration, rainfall interception, energy conservation, pollution removal, and oxygen production. Read more about the tool and how to use it.

ForestCrowns calculates forest canopy transparency using ground-based digital photos. Photo by U.S. Forest Service.
ForestCrowns calculates forest canopy transparency using ground-based digital photos. Photo by U.S. Forest Service.

ForestCrowns calculates canopy transparency (or light transmittance) for digital images taken with standard or fisheye (hemispherical) camera lenses. Specific areas of the photograph can also be targeted to obtain transparency estimates of individual tree crowns. The software can be used by forest managers and researchers to monitor growth/decline of forest canopies; provide input for leaf area index estimation; measure light transmission to the forest floor; analyze canopy gaps; detect disease, insect, or storm damage; and monitor health treatments. ForestCrowns can analyze entire images or target specific areas to obtain transparency estimates of individual tree crowns. The program can also store images and assessment results, allowing for periodic monitoring of canopies and crowns. Read more about the tool and how to use it.

Download the UrbanCrowns software.

Download the ForestCrowns software.

For more information, email Matt Winn at mwinn@fs.fed.us.

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