Tuesday, September 24, 2019

Urban Tree Canopy in Langley City and Metro Vancouver by the Numbers. High Density ≠ Less Tree Cover.

One of the strategic goals of Langley City council is to develop an urban forest management strategy. Tree’s provide important ecological services in urban areas. They combat the urban heat island effect, providing shading and cooling in the hot summer months. They also help manage stormwater and improve the health of streams, reducing flooding and cleaning up water. Trees also store carbon and help clean the air which helps combat climate change and improves human health.

With this in mind, it is critical that we increase the number of trees in our urban areas.

The Metro Vancouver Regional District recently released a report on tree canopy cover and impervious surfaces in our region.

In 2017, the regional district completed a high-resolution land cover classification for all of Metro Vancouver. This is like a high-end Google Satellite view that can be used to find parcel by parcel information on things like what kinds of buildings, the type of agricultural being grown, and the amount of tree cover on each individual parcel of land in our region.

The report was focused on areas within the urban containment boundary as shown in the following map.

Metro Vancouver Urban Containment Boundary. Select map to enlarge.

Areas outside of the urban containment boundary include conservation lands, large parks, rural lands, and agricultural lands. Within the urban containment boundary, the tree canopy covers 32% of the area. When the whole region is measured, including areas outside of the boundary, that number jumps to 54%.

The following map shows the tree canopy cover within the urban containment boundary. The grey areas within the boundary mean near zero tree cover. The darker the green, the more tree cover.

Tree canopy cover within Urban Containment Boundary in Metro Vancouver. Select map to enlarge. 

The following table shows the percentage of tree cover within each municipality. As stated earlier, this is only for land within the urban containment boundary.

Percentage tree canopy cover by municipality within Urban Containment Boundary. Select map to enlarge.  

Langley City is near the bottom of the list, and its not because of the higher density residential redevelopment that is occurring. It is because of the very grey areas along the Langley Bypass and Willowbrook Mall area. These areas need more trees.

Because of how building are constructed today, and the requirement for green space on properties of all densities, there is little difference between low-density and high-density residential buildings that are being constructed.

Average tree canopy by residential density over the years. High density is purple. Low density in yellow. Select table to enlarge.   

What is a good amount of tree canopy cover in urban areas? The Metro Vancouver report notes that it can range from 20% to 60% depending on what the natural environment was in the past. Knowing that most of Metro Vancouver was forested, closer to 60% is likely where we should be aiming for in our region.

Langley City is in the process of updating our Official Community Plan, and I’m hopefully that there will be policies in this update plan to increase the urban tree canopy in our community.

I’ll be posting about impervious surfaces later this week.

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