Existing Trees have Compounding Benefits: Keeping them is a worthwhile investment
A recent study by the American Forests Foundation calculated that to maintain the current levels of urban forest, each urban resident needs to plant approximately 7 trees in their lifetime. To grow our urban forests, that number grows to about 11 trees per person. But planting trees is only part of the story--a big part of maintaining and growing canopy coverage is actually preserving the trees we already have.
Existing urban trees, especially those who have been around for decades, are the most valuable ones. The proverb you’ve probably heard about planting trees, that ”the best time to plant a tree is 50 years ago, the second best time is today”, implies something about the worth of established trees. The ones who have been around long enough to grow upwards and outwards, that give us shade and store carbon now, are the ones doing the most valuable work. Our older, established trees are doing most of the heavy lifting of providing shade, absorbing stormwater, preventing soil erosion, and cooling neighborhoods. Recently planted trees are doing important work too, but they haven’t had time to grow into their full potential yet. Mature trees are the labor force of the urban forest, while saplings are middle schoolers at best. They can definitely do some work around the home like laundry or bathroom cleaning, but they aren’t nearly ready enough for full employment. This is why preserving established trees is a crucial component of any successful urban forestry management plan, including Tacoma’s. Yet current events are proving that preservation doesn’t always have the legal protections/approval that it needs.
The thorny challenges of tree preservation are currently on display all over the South Sound. Lakewood is home to a number of Garry oak trees, the only native oak in Washington state. Only 3% of the original Garry oak population remains, including those in Lakewood. The prairie habitat that Garry oaks grow in is a special habitat by state designation but the trees themselves aren’t fully protected from development impacts. Proposed warehouse projects could level these special trees in a habitat that’s been nurtured by indigenous tribes for centuries. Losing these trees in Lakewood isn’t only an issue of history or ecology though. While Lakewood has a lot of tree canopy in the west side of town, there’s very little in the east. Losing those oaks would mean the east side will now have even less canopy coverage.
It’s not just in Lakewood either where established trees are coming down. A large tree removal project above Salmon Beach has residents asking questions about how the established minimums for tree coverage are both set and enforced. The Salmon Beach case perfectly illustrates that for many developers, the costs of over-cutting trees is minimal, even negligible. This is despite how costly the downstream impacts of that cutting can be, both to taxpayers as well as private property owners.
In Federal Way, the 429-acre Weyerhauser campus has been acquired by private developers looking to establish warehouses within easy access of I-5. Over 100 acres of forest are proposed to be cleared for warehouse construction, with little consideration of how this removal would affect the surrounding watershed. Concerns also include disruption of habitat for wildlife too, as breaking up forest has negative consequences on the wildlife that call that area home.
The iconic Weyerhaeuser headquarter building on the campus.
Although the City of Tacoma's adopted Urban Forest Management Plan calls for tree preservation measures, there are currently no tree preservation codes on the books. Furthermore, compared to Seattle, Tacoma’s fines for overcutting trees are minimal and don’t take into account the level of ecosystems services provided by the impacted trees. There is no policy to protect trees, and no strong disincentive not to cut down more trees than development permits allow.
Tree preservation isn’t as photogenic of an act as tree planting, and cutting down trees is almost always followed by paying for forgiveness rather than preceded by asking for permission. Having a strong urban tree preservation policy that’s both enforceable and actually enforced goes a long way towards preserving valuable urban forest trees. It’s a way of ensuring that the trees we plant today have a chance of making it to 50, or even older. This is why tree preservation is part of the Tacoma Tree Foundation board’s strategic plan. Tree preservation should be the cornerstone of any practical urban forest policy, because it’s also the cheapest action as well as the most obvious. You don’t need a shovel to preserve trees, just some common sense.