A year ago, Vancouver was among dozens of Washington locales to earn the designation of “Tree City USA.” The honor comes as no surprise; we are, after all, part of The Evergreen State, a region marked by both expansive forests and abundant deciduous plants.
But as an article from Columbian reporter Lauren Ellenbecker points out, such designations are being threatened by a changing climate. In addition to weather-driven migration, extreme weather events and rising sea levels, a warming planet is impacting the kinds of vegetation that can thrive in various locations.
“Our palate of trees is going to have to change,” Charles Ray, Vancouver’s urban forester, told The Columbian. “We need all development projects, as well as private property owners, planting large climate-forward species, not small ornamental trees that do not provide the ecosystem and public health benefits.”
Whether in urban areas or in forested lands, trees are essential to mitigating climate change, which resulted in July being measured globally as the hottest month in recorded history.
Trees sequester carbon, which is a leading cause of warming temperatures, and a 2019 study published in the journal Science claimed that globally planting 1 trillion trees — more than 120 for every person on Earth — could capture more than one-third of all the greenhouse gases humans have released since the Industrial Revolution.
That conclusion has been disputed, but planting trees should be one leg of a multipronged approach for combating climate change. Restoring forests, cutting carbon emissions, reducing the burning of fossil fuels and protecting rainforests also are essential to curbing the global threat.
“Trees do take carbon out of the atmosphere, and if you want to permanently store carbon in trees, you have to permanently commit to keeping the trees forever,” University of Chicago geophysical sciences professor David Archer said. “The fossil fuel carbon is so much bigger than all the carbon in the trees. You can’t do carbon neutral by planting trees. … It’s sort of a Band-Aid.”
But Band-Aids can be useful; in an urban setting, a robust tree canopy has been shown to decrease temperatures on the ground. And a 2021 assessment by PlanItGeo determined that Vancouver’s canopy saves about $44 million annually by removing pollutants, reducing stormwater runoff and sequestering carbon.
As of last year, Vancouver’s tree canopy covered approximately 18 percent of land in the city; by comparison, Seattle was at 28 percent and Tacoma at 10 percent. A study from Washington State University concluded: “The urban canopy enhances the environment, increases community attractiveness and fosters community civic pride, while balancing economic growth with environmental quality.”
Preserving that canopy has become more difficult, as many native plants are not suited for increasing temperatures. Vancouver officials have assembled a list of climate-adaptive trees that are likely to persist under intensifying conditions.
As Ellenbecker writes: “Extreme heat causes tree leaves to close their stomata, pores that allow the plant to cool itself, and causes the tree to slow its growth to conserve resources. A lack of water during droughts can lead to nutrient deficiency and weaken a tree’s immunity, making it susceptible to pests and disease. Eventual symptoms can look like leaf scorch, wilting and dying twigs.”
All of which serves as a harbinger for the future. If we want to know how Vancouver is adjusting to climate change, we can simply look up.