Tree Survey Protocol

MyTree Tree Survey Protocol

 

BEFORE TREE SURVEY

A. You might need

  1. Smartphone with MyTree App installed (required)

  2. Measuring tape or DBH tape (highly recommended)

  3. Digital Distance Measurement Device (optional)

  4. 30m measuring tape (optional)

  5. 1.3m string to mark the Point of Measurement (POM) (optional)

  6. Partner(s) is preferable

 

B.  MyTree App Installation and Set Up

  1. Please install the MyTree App via App Store or Google Play.

  2. Enable “Location Service” and select “Precise Location” once you launch the App, then press “Start”.

  3. Allow “Camera” access

  4. You are required to register an account to have full access to the MyTree App.

  5. Now you can view tree records and submit your tree data. 

 

CONDUCTING TREE SURVEY

A. Choose a Tree

  1. Choose a tree that is located along the trail, preferably within country park areas, and has a minimum height of 1.3m and a Diameter at Breast Height ("DBH") of 15cm (or a tree circumference of 47cm).

  2. Observe if the tree is dead or alive by examining the available leaves. If you consider the tree dead or uncertain, move on to the next tree.

  3. Open the MyTree App (“App”) and create a new tree submission by clicking “Submit”.

  4. No worries if you can’t fill in all the fields listed on the submission form. Only photos and location are mandatory fields for each tree submission. 

 

B. Tree Location

  1. Stand near the trunk of the chosen tree before data entry. Then click “🌳+Submit” at the bottom right corner. The App will automatically record your current GPS location, and show the location at the “Tree Location” field. 

  2. If you notice the GPS location is incorrect, you can click on the location map and the App will relocate your current location. If you agree with the marked location, click “Confirm”. If not, please check your “Location Service” setting in your phone and make sure that “precise location” is turned on. Then re-launch the App and submit tree data again. 

  3. If the marked location is still incorrect, please continue to proceed with the data entry and submission, and inform us about the incorrect GPS location in the “Other” field on the submission form.

 

C. Tree Photos

  1. There are four photo categories, including Whole Tree, Trunk, Leaves, and Others, at the top of the submission form. Click on the category box, which allows you to take pictures using the photo camera. You have to enable your “Camera” before taking photos.

  2. Please take ONE photo of each of the following: whole tree, trunk, and leaves. Please centre the object in the frame. If you would like to submit more than one photo of the above categories, please submit them in the “Others” category.

  3. If the tree has flowers or fruits, please submit photos of those in the “Others” category, which allows you to upload up to 10 photos. 

 

D. Tree Species

  1. Observe the tree's characteristics and use your knowledge to identify the species. 

  2. If the tree species doesn’t appear on our tree list (search suggestions), please select “I don’t know/ Species not provided” and enter the species name in the “Other” section below.

  3. If you are unable to recognise it, please select "I don’t know/ Species not provided". If “I don't know” is selected, the tree species will be displayed as “Species not provided”. 

 

E. Number of Stems

  1. If the tree has multiple stems (not at a pitch intersection) at the POM, or if the tree splits into multiple stems close to the ground level:

    1. If the tree is located on a slope, please measure at the upper slope.

    2. Avoid measuring irregular spots on the tree, such as bumps or branches. In such cases, measure the DBH below those spots and select the corresponding POM in the dropdown list (i.e. 1.2m, 1.1m or 1m) in the App. 
       

  2. At the POM, observe the number of stems which have a DBH larger than 15 cm (Circumference larger than 47cm).

  3. Select the corresponding number of stems you observed in the dropdown list of the field “No. of Stems”.

  4. Each stem should have its own POM, DBH/ Circumference, and Height measurements. You need to enter those data separately for each stem on the form.

  5. If you select more than one stem, the extra stem data form(s) will be shown below. 

**Note: If you reduce the number of stems during data entry, the last dataset(s) will be removed. For example, if you change the No. of Stem from 4 to 2, the Stem 3 and 4 data will be removed.

 

F. Tree Height (in metres) (from the trunk above the ground level to the highest living leaf)

  • Method 1 (Highly recommended): Measure the tree height using the digital distance measurement device if you have one.
     

  • Method 2 (For iPhone users): You can use the “Measure” App and proceed with the following steps to measure the tree height.

  1. Open iPhone “Measure” App. **Note that if you don’t have the “Measure” App on your iPhone, you can download it from the Apple Store.

  2. It is recommended to maintain a distance of 2m from the tree, but this may vary based on the instructions provided in the “Measure” App.

  3. Use the “Measure” App to measure the height from the bottom to the top of the tree. 

  4. Record the measured height in the MyTree App.

  5. If the tree has multiple stems, the height of each stem should be recorded. 
     

  • Method 3 (Least preferable): You can estimate the tree height by your observation. 
     

  • Method 4 (I really don’t know): If you cannot provide the tree height, you can select “Tree height not provided” on the submission form.

 

G. DBH Measurement (in centimetres)

  1. Once you identify the POM and Number of Stems, measure the DBH or circumference at the POM using a DBH tape or measuring tape.

  2. Record the DBH or circumference in cm in the App. Only enter either DBH or circumference and the App will automatically calculate the other variable.

  3. If the tree has multiple stems (not at a pitch intersection) at the POM, or if the tree splits into multiple stems close to the ground level:

    1. Follow the aforementioned procedure to record the DBH for each stem.

    2. Only stems with a DBH equal to or greater than 15 cm should be recorded.

    3. Stems from the same tree will be recorded in the same submission form in the App.

    4. If there are trees that grow very close to each other or possibly share the same pitch intersection below ground, they are considered as separate trees. This means that each tree should have a different submission form in the App. 

  4. Please refer to the POM scenarios outlined in the Diameter at Breast Height Measurement document.

 

H. Crown Base Height (in metres)

  1. It is defined as the height from  the ground to the base of the live crown (i.e. the lowest branches).

  2. You can use the methods listed in “Tree Height” (Section F) to measure the crown base height. Please leave it blank if you don’t know.

**Note: If you provide any Crown Measurements (Crown Base Height & Width) of the tree in the submission form, you are also required to provide the tree height.

 

I. Crown Width (in metres)

  1. Before conducting the measurement, it is recommended to observe the entire tree crown and identify the edges of the live crown.

  2. Find the length that can represent the average width of the living crown. Avoid measuring the length showing the widest or narrowest width of the crown.

  3. You can use the measuring tape, digital distance measuring device or iPhone “Measure” device to measure the crown width.

    1. Conducting the measurement with partner(s) is highly recommended.

    2. If you use measuring tape, please make sure you pull the tape tight and keep it horizontal before you read the recording. Avoid putting the tape on the ground for measurement if you are on a slope. 

  4. No worries if you don’t have the tool for measurement. You can leave it blank if you don’t know.

 

J. Other

You can provide other observations/ note in the field, for examples: 

  1. Tree characteristics or surrounding environments to recognise the location and to determine the health conditions of the tree

  2. Alternate measurement methods that are different from this protocol

  3. Incorrect GPS location

  4. Any other observations

 

K. Submission

  1. Once you finish the data entry, click “Preview Submission” at the bottom, and review the data you entered.

  2. Click “Submit for Approval” if you confirm the data is entered correctly.

  3. Then your tree record is under “In Review” status. The status will be changed according to our experts’ validation. 

  4. You can review your submitted tree records under the “My Record” tab and your records will be displayed as a person icon on the map.

 

REMINDER

  • Safety is always the top priority. Pay attention to the spot and surroundings where you are standing while conducting the measurement. Be cautious of any potential hazards, such as steep slopes, irregular terrains, wasp nests, etc.  

  • Ensure no harm is caused to the tree and surrounding nature during the survey. Refrain from taking any natural objects with you. Show respect for wildlife and make an effort not to disturb any animals. 

 

CREDITS

The submitted tree data will be used for calculating the eco-benefits metrics, including Carbon Storage, CO2 Removal and Air Pollution Removal (O3, NO2, PM10). The metrics are provided by Dr. Billy Hau from School of Biological Sciences at The University of Hong Kong, and also retrieved from the past scientific literature review (Manzini et al., 2023; Nowak, 2021; Nowak, 2002).

 

REFERENCES

Manzini, J., Hoshika, Y., Carrari, E., Sicard, P., Watanabe, M., Tanaka, R., ... & Paoletti, E. (2023). FlorTree: A unifying modelling framework for estimating the species-specific pollution removal by individual trees and shrubs. Urban Forestry & Urban Greening, 85, 127967.

Nowak, D. J. (2002). Brooklyn's urban forest (Vol. 290). USDA Forest Service.

Nowak, D. J. (2021). Understanding i-Tree: 2021 summary of programs and methods. US Department of Agriculture, Forest Service, Northern Research Station.

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