Step 1: Count the number of trees on your block

Walk along one block in your neighborhood and count the number of trees along the street and in front yards. Record this number.

Step 2: Document and measure the diameter of five trees

Find five trees that you have access to. (You need to be able to get close enough to touch the trunks of the trees.)

For each tree, you will need to take a picture of the tree and measure its diameter. (If you are unable to take a picture, you can sketch the tree instead.) Diameter at breast height (DBH) is the standard way to measure the size of a tree. DBH is the diameter of the tree at approximately 4.5 feet above the ground.

You can measure the diameter of the trees by using a fabric tape measure (Links to an external site.) or a free measuring app (Measure app for iOs (Links to an external site.) or Smart Measure app for Android (Links to an external site.)). Note that these measuring apps can be a bit finicky and you will need to stand quite close to the tree to obtain accurate measurements. For this assignment, you will need to know the DBH in inches.

If you are using a fabric tape measure:

1. Measure 4.5 feet above the ground.
2. Wrap the tape measure around the tree at this point. Write down the measurement; this is the circumference.
3. Divide the circumference by 3.14. This will give you the diameter of the tree.
4. Record the diameter of the tree and repeat this process for all trees in your area.

If you are using an app:

1. Measure 4.5 feet above the ground.
2. Use the app to measure the diameter (width) of the tree.
3. Record the diameter of the tree and repeat this process for all trees in your area.

Make sure that you complete this assignment during the day; the app won’t work well if the tree isn’t well lit. If you get stuck when using an app, use the information below to help you troubleshoot:

• Use the Measure app on iPhone, iPad, or iPod touch (Links to an external site.)
• Use the Measure app on Android Devices (Links to an external site.)

Malone, Thomas; Liang, Jingjing; Packee, Edmond C. 2009. Cooperative Alaska Forest Inventory. Gen. Tech. Rep. PNW-GTR-785. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 42 p. This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

Step 3: Estimate the total amount of carbon sequestered on your block

Use the table below to help you determine the total amount of carbon sequestered by all the trees in your area. The values in the table can be interpreted according to the following definitions:

• Carbon sequestration (lbs/year) – estimated amount of carbon removed annually by trees

Average amount of carbon sequestered by tree diameterDBH (inches)Carbon sequestrationlbs/year1-32.53-67.66-914.09-1219.912-1527.015-1850.018-2159.721-2486.724-2790.627-30111.630+155.5

Nowak, David J.; Hoehn, Robert E. III; Crane, Daniel E.; Weller, Lorraine; Davila, Antonio. 2011. Assessing urban forest effects and values, Los Angeles’ urban forest. Resour. Bull. NRS-47. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 30 p. https://doi.org/10.2737/NRS-RB-47 (Links to an external site.).

Calculate the average amount of carbon sequestered for all the trees that you measured by adding together the amounts for each tree and dividing the total by 5. Estimate the amount of carbon sequestered by all of street trees on your block by multiplying the average amount of carbon  by the total number of trees you counted. Use this information to complete the table:

Tree (1-5)DBHCarbon Sequestered lbs/yearTotalsAverage (total/5) 

Total Carbon Sequestered on your block

(Average X the number of trees on your block)

Step 4: Determine tree canopy cover for your neighborhood

You will use the Healthy Places Index (HPI) map to determine what the tree canopy cover is in your neighborhood and see how it compares to other neighborhoods.

• Go to the Healthy Places Index (Links to an external site.) map. 
• Search for your neighborhood in the search box at the top of the page. 
• Click ‘View Indicators’ and then select ‘Neighborhood.’ Choose to view ‘Tree Canopy’ on the map.  This variable is a measure of the percentage of land with tree canopy (weighted by number of people per acre). When you click on a census tract, you will be able to see what the tree canopy cover is for that census tract and how it compares to how that census tract compares to other census tracts in California. In the image below, see an example of tree canopy cover data for the census tract containing Pasadena City College. Note that in the pop-up box, the first value is the percentile, which indicates how this census tract compares to other census tracts, and the number in the parenthesis is the percent canopy cover. 

The following screencast provides an overview of how to get the tree canopy cover data for your neighborhood from the Healthy Places Index Map: 

Submission Guidelines

Now that you’ve collected data about the trees in your neighborhood and calculated the total amount of carbon sequestered, include the following in a file (Word doc or pdf):

1. The number of trees on one block in your neighborhood. 
2. Pictures of the trees that you measured and the DBH and amount of carbon sequestered for each
3. Total amount of carbon sequestered by all of the trees on your block. 
4. Your neighborhood’s canopy cover values from HPI and that of a three comparison neighborhoods. Comparing the canopy cover in your neighborhood to others in Los Angeles County, should your neighborhood be a priority for urban tree planting efforts? If not, identify another neighborhood that should be a priority. Explain how the data from the HPI map supports your recommendation.
5. In addition to carbon sequestration, what would be 2 potential benefits for the neighborhood if additional trees are planted?