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Tree Blog The Dying Trees
Shades of Green As it turns out, not all green is good. Take a walk in your neighborhood forest. If it’s like most forests in Seattle, just before you enter the trees you’ll find impenetrable thickets of Himalayan blackberry (Rubus discolor). Once inside the forest, there will likely be a thick carpet of the dull waxy green leaves of English ivy (Hedera helix), spilling out across the forest floor and even reaching into the tree canopy. Though lush and green, these invasive plants and several other new species to the area are replacing all the native plants in the forest, including the trees that make up the forest itself. Time to Kill How do these invasive plants kill our trees and other native forest species? Given time, ivy, blackberry and a few other plants will blanket the ground, shutting off light and resources for any other plant to survive, including tree seedlings. Once established on the ground, ivy will surround and climb tree trunks, eventually growing out to branch tips and smothering trees whole. If that wasn’t enough, as the ivy weakens the tree by covering its leaves, it also adds a great deal of weight, with ivy trunks on some trees as thick as a man’s thigh. Once so weakened, winter storms over time can bring down the forest, tree by tree. It is estimated by Seattle Urban Nature that without intervention, 70 percent of Seattle’s forested parklands will be lost in 20 years due to invasive plants due to invasive species. Turning a New Leaf The decades of neglecting our forested parklands, decades that have given invasive plants the time to kill, are not the result of malicious intent. We came to realize that many natural areas, if disturbed, are not self-sustaining, but need to be cared for. At times our care of the forest is even like tending a garden, with a time to weed, a time to prepare the soil and a time to plant. And because we now live in a world with many disturbances and many sources of new threats, we need to monitor and maintain our urban forests to keep them healthy. How we keep our trees from dying, create a vision for the future forest and take tangible steps to achieve that vision will be the subject of our next blog. In acting on this vision, we’ve found it’s not just the forest that returns, but also our sense of shared community and a collective hope that we will together leave the world a better place than we found it. Share a comment on this blog posting Comments
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Our city’s trees are in serious decline. The once vast stretches of mature forest that lined our shores, reached out to the mountain foothills and filled Puget Sound Basin are largely gone. In addition, over the past 150 years virtually all of Seattle’s remnant forests have been logged, giving way to younger forests, particularly of big-leaf maple (Acer macrophyllum) and red alder (Alnus rubra). Now, after decades of passive management, even these forested parklands are in danger of being lost. This threat comes not from development or from the blade of an ax. This threat comes from decades of benign neglect.