Invasive Species: Emerald Ash Borer

The  Emerald Ash Borer  (EAB), an invasive insect first identified in Canada in 2002, has severely affected the ash tree population in the Town of Oakville, Ontario. EAB is one of North America's most destructive forest invaders. It decimates ash trees by feeding on their inner bark, blocking nutrient and water flow, leading to rapid tree decline within one to three years.

While pests and diseases can typically play roles in forest health and biodiversity, climate change worsens the challenges posed by EAB in Oakville. Rising temperatures accelerate the beetle's reproductive cycle, expanding its range and infestation rates. Climate-induced stress weakens tree defenses, making them more susceptible to pests like EAB.

Oakville's urban tree canopy is vital for mitigating climate change impacts and enhancing quality of life. Trees improve air quality and reduce urban heat. Maintaining a diverse and healthy tree canopy beautifies neighbourhoods and supports residents' well-being. Preserving and diversifying tree species in urban areas is crucial for resilience against pests like the Emerald Ash Borer and climate change effects.

In this lesson, you will use ArcGIS Online to explore, assess and analyse tree data related to the EAB issue in Oakville.

This lesson includes four (4) inquiries linked to the EAB issue in Oakville. We have included the time required for each inquiry. Depending on your allotted time, your students can complete as many inquiries as you see fit.

Time Required to Complete Lesson: Completing all inquiries and tutorials will take approximately two (2) hours.

Note: The data used in this lesson was accessed from the  Town of Oakville's Open Data Portal  in April 2024. It may not include the most recent data. However, for the purpose of the lesson, the data will suffice.

This question sheet can be printed out or shared online for the students to use when answering the questions throughout the lesson.

You are a GIS Analyst at the Town of Oakville. Your role is to support the Trees, Parks, and Woodlands (TPW) department to create maps for public meetings. Your expertise in mapping and spatial analysis will play a crucial role in addressing and communicating the EAB infestation and the condition of existing ash trees, aiding in developing effective mitigation strategies and ensuring the health and sustainability of the urban forest.

In Oakville, the largest town in Ontario, ash tree species include green, white, blue, black, and pumpkin ash.

Mountain ash and prickly ash are NOT affected by EAB as they belong to different tree families. They are NOT true ash trees.

Complete the following tutorial:

1.   Adding and Working with Data in the Map Viewer   (30-40 minutes)

Addtional tutorials are included throughout the Lesson for your reference. Look for the💡.

1. How to  Aggregate Points  (Inquiry #2)
2. How to create a  Heat Map  (Inquiry #2)
3. How to create a Spatial Query using  Find Attributes and Locations tool  ( Inquiry #3 video )

Map the condition of Ash Trees in Oakville.

1. Open the  Inquiry 1 map  and Sign into your account.

Filters allow you to create a subset of a dataset. To view the condition of ash trees in Oakville, you will create a series of filters on the Tree dataset.

 Adding and Working with Data in the Map Viewer  

1. View the Exisiting Ash Trees by creating 2 expressions using the following fields: "Status" and "Species." Make sure you select the correct ash species types. Refer to the previous section to identify the true ash trees. Q1) How many existing ash trees are there in Oakville? (Hint:  Open the table  to view the results)
2. Build onto your current filter by finding the existing ash trees in fair , good and excellent condition using the "Condwood" field. Q2) How many ash trees are in "fair, good or excellent condition?"
3.  Duplicate   (Create a new layer) the Tree layer and rename it to "Fair to Excellent Trees."
4. View the existing ash trees in poor, very poor, dying/dead condition using the "Condwood" field. Q3) How many ash trees are in "poor, very poor, or dying/dead condition?"
5. Duplicate the Tree layer and rename it to "Poor to Dead Trees."
6. View the existing ash trees that have been recommended to be “takedown” by management using the field "MGT_REC1" Q4) How many trees have been recommended to be taken down?
7. Duplicate the Tree layer and rename it to "Trees to Remove."
8. Save the map and name it something appropriate.

TreeAzin is a biological pesticide that is used to increase survival rates of EAB infected trees in the Town of Oakville.

To visualize the EAB issue, you will create a heat map to see the distribution and concentration of TreeAzin treated trees. You will also use the  Aggregate Points Analysis  tool to summarize the number of treated trees within each Ward.

Heat Map

1. Open the  Inquiry 2 map  and Sign into your account.
2. Create a 💡 Heat Map showing the location of the TreeAzin treated ash trees in Oakville.  Adding and Working with Data in the Map Viewer   tutorial (Part D) Q1) Do you notice any patterns? Briefly explain them.

Aggregate by Ward

1. Create a 💡 choropleth map  showing ash trees treated with TreeAzin aggregated by ward. Make sure the Wards layer is present on the map.
2. Save the map and name it something appropriate. Q2) Which wards contain more treated trees?

Possible Hazards Ash trees infected with EAB become brittle and structurally unsound because the larvae tunnel under the bark, depriving the trees of nutrients. This brittleness can result in limb breakage or tree falls, posing significant risks to trail users and potentially causing severe damage to nearby properties.

1. Open the  Inquiry 3 map  and Sign into your account.
2. Create a filter using the Tree layer to view only the existing ash trees that are poor, very poor, dead or dying condition using the Condwood field.  Adding and Working with Data in the Map Viewer  tutorial
3.  Duplicate  the Tree layer with the filter and rename it Poor Trees.
4. Go back to the original Tree layer and delete the filter.
5. Create a spatial query using the 💡  Find by Attributes and Location  tool. Enter the following expression - poor ash trees within 100m of a trail in Oakville outlined in the video below. Q1) How many ash trees will need to be removed near trails?

Woodland Ash Trees Ash trees in woodlands can cause significant ecological and economic impacts as trees are closer together and infestation rates can be higher.

1. Create a filter with the original Tree layer to view only the exisiting ash trees.  Adding and Working with Data in the Map Viewer   tutorial
2. Create a spatial query using the  💡Find by Attributes and Location  tool to identify the ash trees that intersect with woodlands. These trees will need to be removed by the Town of Oakville. Use the video below for reference.
3. Save the map and name it something appropriate. Q2) How many trees would need to be removed because they are in woodland areas?

Following the removal of ash trees affected by EAB, the Town of Oakville must plant  diverse tree species  to replenish and restore the urban tree canopy lost to the infestation. Let's see where trees will be planted and what species they will be.

Trees on Planting List

1. Open the  Inquiry 4 map  and Sign into ArcGIS Online.
2. Using the "Status" field, create a filter to see where new trees will be planted.
3. Once you have created your new subset of data,  duplicate  the layer and rename it to Trees on Planting List.
4. Symbolize the Trees on Planting List layer to show the "Species" of trees that will be planted in Oakville. Use the video below to see how to do this.

Q1) Why is it important to plant different tree species?

Number Trees on Planting List by Ward

1. Create a  choropleth map  showing trees on the plant list 💡 aggregated  by Ward. Use the video below to see how this is done.
   1. Make sure the ward boundary layer is present on the map.
   2. Label the Wards based on the total number of trees aggregated on the plant list.
   3. Explore the map.
   4. Save the map and name it something appropriate.

In this lesson, you used ArcGIS Online to analyse tree data related to the EAB issue in Oakville and created maps that you can be used by the Trees, Parks, and Woodlands (TPW) department at public meetings.

Continue your learning by exploring the Career Path Series. Students will learn not only about GIS, but also about the myriad of career opportunities it opens up, inspiring the next generation of data analysts, decision-makers and industry innovators.

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