Climate change is affecting the long term survival of our urban forest. Metro Vancouver is developing guidelines and education materials to help landscapers choose trees that can adapt to our region’s urban environment and weather conditions.
Urban trees in Metro Vancouver certainly offer natural beauty but they are also working for us in less visible ways. Josephine Clark, Regional Planner for Metro Vancouver explains how trees provide ecosystem services. “These services are not only making our cities pleasant places to live they can also help us adapt to climate change,” she said. “For example, they provide shading and cooling on hot days, they capture and hold rainwater, they store carbon.”
With a changing climate creating new weather patterns, urban trees in the region are being put under added strain. “Climate projections indicate that we are going to have warmer and drier summers and also heavier rainfall events in the other seasons,” said Amelia Needoba, Senior Urban Forester, Diamond Head Consulting. “From the trees’ perspective that warmer, drier summer is going to result in reduced water supply and less availability for growth, resulting in increased tree mortality.”
Metro Vancouver has been researching how to protect our urban forest in the future. “There wasn’t a lot of guidance about how we should be planning and managing our urban forests to make sure they will be resilient and also how vulnerable they were to the impacts of climate change,” said Clark. “So working with urban forest practitioners, we looked at generating a framework to make decisions about the trees that we plant and how to increase resilience and reduce vulnerability.”
Metro Vancouver worked with Diamond Head Consulting, an environmental firm that specializes in ecosystem planning, design and management to research and create a guidebook. “The guidebook is focused on how to use trees to maximize the climate adaptation benefits that they provide,” said Needoba. “Where do you place trees to maximize benefits that you might want for shade or for rainwater interception? How would you plant those trees and what kind if considerations should you look at when selecting trees to plant in that environment?”
Choosing tree species carefully is one of the most important considerations that determines their resilience. Specimen Trees in Pitt Meadows grow more than 728 species of tree. Operations Manager Sandy Howkins says they are looking for trees that can deal with both hot, dry summers and handle our wet, mild winters.
“Just because a tree is commonly found in our local forests does not make it suitable for our cities; the urban forest is a very different beast to our natural ecosystem,” said Howkins. “If you take a Douglas Fir and put it down into Commercial and First, that’s a really tough go. You’ve got very hot conditions, reflective light, poor water conditions and the soil is heavy. Douglas Fir is a surface rooting tree, not deep rooted. It doesn’t perform.”
Some of the trees that thrive well in Metro Vancouver cities are not indigenous to British Columbia. Howkins points out a specimen called Parrotia persica. “It’s from Persia and seems to be able to deal with urban pollution, hot dry summers and wet winters,” he said. “So this is a great example of taking a tree from a different part of the world and it finding its place in the Vancouver area and performing very nicely.”
Selecting trees that will have resiliency in future climates as well as growing them well in advance has unique challenges. “To assess the climate suitability of trees we have run an analysis on about 140 trees that are commonly planted or found in the urban forest,” Clark said. “It provides a range of basic characteristics as well as climate suitability.”
With continued research and education, growing healthy trees that are well-adapted for future climates and spaces will ensure a healthy urban forest canopy.
Metro Vancouver’s Urban Forest Climate Adaptation Project Resources:
Visit our video gallery for more stories about urban planning and conserving & connecting natural areas.