PUGET PARK TREE-THINNING: Why hundreds of trees will be removed, before thousands are planted

(WSB photo: Looking into the West Duwamish Greenbelt from the northeast edge of the SSC campus)

By Tracy Record
West Seattle Blog editor

An unusual forest-restoration project – involving a significant amount of tree-cutting as well as tree-planting – is about to get under way in eastern West Seattle’s Puget Park, after three years of planning.

The project leader says it’s work that will have benefits for decades and centuries to come – but it’s a project unlike any other they’ve undertaken, and they want people to understand why it will require taking out hundreds of trees (an estimated 600 “stems” – some trees have more than one).

We went to a weekend briefing to find out more firsthand. It’s a Seattle Parks project under the umbrella of the Green Seattle Partnership, which will have 1,500 acres in restoration citywide by year’s end. The challenge here is that the area has an “unnaturally dense hardwood canopy” – far out of balance with evergreens, and bringing them back requires removing some of that dense canopy.

Here’s what plant ecologist Michael Yadrick from Seattle Parks told attendees about what’s going to be done and why:

Speaking in the Chan Education Center on the north side of the South Seattle College (WSB sponsor) campus – steps from the west edge of the forest – Yadrick said he’s been with Parks for about seven years and focuses on the west side of the city. 2,500 of the 6,414 acres that Parks owns is ‘destined for restoration’ – that’s five percent of the city’s land mass. The West Duwamish Greenbelt is four miles long, from Pigeon Point to Westcrest Park.

The city’s recent tree-canopy assessment (see a map at seattle.gov/trees/canopycover) shows that this area has a decent canopy – the highest percentage is in east West Seattle (Delridge), 38 percent, because of the natural areas like this one.

The project area is from Brandon Street south to the SSC aviation center, 24 acres, with 30 percent of the “native hardwoods” (which comprise about 95 percent of the trees in Puget Park – compared to 72 percent citywide) to be taken out, creating gaps for conifers that are there now – or to be planted – to grow. The trails in the area, by the way, are not officially part of the city’s 120 miles of trail, in part because it dead-ends and crosses some private property, it was pointed out.

The project also will include “understory treatment” – weeding out blackberry, etc. – and will be followed up with planting of 10,000 native trees and tall shrubs.

The “need to do this sort of work” was established a long time ago, Yadrick said, but it just hasn’t been done. So they started consulting and researching in 2014. He showed a list of more than 15 groups with which he’s consulted, including many tours in recent months, to “vet the concept” and “talk about what it means to folks.” It’s taken a “serious amount of consideration” because of the project’s nature.

He stressed, “It’s not a traditional ‘logging’ project” – it won’t be a clearcut-type of situation.

What happens if it’s not done? In another decade or two, “invasive plants outcompete and cover existing native vegetation, leaving little light for young plants to establish. English ivy thrives in the tree canopy, making trees top-heavy and susceptible to wind. Eventually trees die or fall over.” And then in another few decades, no trees, mostly just invasive plants like ivy. The trees that are dominant right now include red alders, which reach their maximum height in 40 years but become mature within the first eight. They need full sun, so in a conifer forest they wouldn’t take over like this. “It definitely has its place in the forest, but we’re shooting for a little more balance.” Big-leaf maples are taken over by ivy, too. To fight that, Yadrick explained “ivy rings” that can be placed – though it’s labor-intensive; he talked of an eight-acre spot that required 900 of them – Green Seattle Partnership has placed hundreds of thousands of them, he said. When they’re not full of ivy, as in other forests, they might be draped in mosses and lichens, he noted. But around Seattle, bigleaf maple and red alder are the top two “failing” tree species (followed by Pacific Madrone and Douglas Fir, Black Cottonwood, Willow, Deodar, Cherry, Western Red Cedar, Black Locust) – even though most of those are native. “The trees are just starting to fall apart.” They’re also susceptible to some diseases – he mentioned a study of “verticillium wilt” causing dieback and decline in bigleaf maple.

Back to the restoration plan, they also work to control “non-native trees,” such as English holly – “one of the more despised trees in the forest.” And when they replant, they go for shade-tolerant conifers – like grand firs – so they have a better chance of early survival. They could grow to 200 feet, but it’s slow going, and they don’t even bear seeds until they’re 20 years old. But eventually they’ll “shade out” the invasives. This is all an attempt to “jump-start” a healthy forest.

The “before” photo is more accurately, Yadrick showed, a picture from two winters ago, when the deciduous trees are devoid of their leaves, and the landscape is rather sparse looking, compared to the “leafed-out” spring and summer scene.

Part of Puget Park – to the north – has had some restoration work since 2008; the central part, for the past four years; the south part, just beginning. “The reason why we chose this spot” for the thinning project “is that it’s fairly flat,” he said. Also, not many “public hazards” since there’s “limited recreation” in the area. They won’t be cutting on the steep slopes (a map shown during the presentation showed some of them with orange – 70 percent slopes – and red coloring – 100 percent). And again, the replanting will cover 40 acres, while the thinning will cover 24. But the gap creation, and growth of new trees, also will lead to “natural regeneration” as the years go by. The conifers also will help with stormwater retention in winter rains, compared to leafless deciduous trees that dominate the site now.

So far, they’ve marked more than half the site, with paint on the trees slated for removal. A similar thinning project was done on five acres of Discovery Park in north Seattle, Yadrick said.

They won’t start the Puget Park cutting until mid-August, because of bird-nesting season. To support wildlife, he said, the snags that are already standing will be kept. And since they have “no mandate to remove wood from the site,” the downed trees will be kept on the site, creating some “nurse logs,” which are also habitat for small animals. They’ll be planting “in and around the dead wood … it won’t be an evenly spaced plantation-type situation.”

The replanting will include not only conifers but also trees that can “grow into the middle of the forest as well.”

This will be a sort of “test project,” Yadrick acknowledged in Q/A – and after this, they will “step back and assess where else we could do this” in the city, taking into account factors including public sentiment and cost.

WHAT’S NEXT: As mentioned above, the work is expected to start in mid-August. The timeline published in this detailed post on the Green Seattle Partnership website is as follows:

Carry out the thinning and gap enhancement operation from mid-August through mid-October 2017

Replanting will be complete before the end of March 2018, and

Monitoring via GSP long-term monitoring plots and inventory starting spring 2018

5 Replies to "PUGET PARK TREE-THINNING: Why hundreds of trees will be removed, before thousands are planted"

  • junctioneer July 12, 2017 (1:27 pm)

    This is awesome. I didn’t know we did proactive stuff like this. So many green areas are dominated by blackberry, ivy, and bohemian knotweed. How can we do more? Are there plans to do this in other parts of the city?

    • WSB July 12, 2017 (1:31 pm)

      The Green Seattle Partnership already has 1,500 acres in restoration – if you follow the link at the top of the story, lots of info on their website. And the briefing included a mention that while they have some volunteer forest stewards, they can use a lot more, particularly in the West Duwamish Greenbelt here ….

  • D Del Rio July 12, 2017 (3:11 pm)

    Several years ago I volunteered for the Nature Consortium. While we didn’t do any thinning, we did pull out invasive species during the spring and summer months, and planted native conifer and native ground cover during the fall and winter. If you ever walk the trails of the West Duwamish starting at the Highland Park Way or 14th Ave. and Holly Street entrances, you will see many conifers that where planted up to ten years ago. It is so nice to see the evergreens that now tower over even the tallest person. I would say over 90% of the young conifers in this area have been planted by groups like the Nature Consortium, and possibly by Earth Corps.

    • datamuse July 13, 2017 (8:26 am)

      I used to volunteer for them as well and learned a lot about why this kind of work is necessary. As I understand it, a contributing factor is that this area was clearcut about a century ago and then just sort of left to itself. Invasive opportunists like blackberry and ivy tend to flourish in that environment.

  • Lindsay July 14, 2017 (4:39 pm)

    I’ve spent some time in this forest and observed that much of the alder is reaching the end of its natural lifespan (~70-100 years). Each fall and winter storm season alder trees fall down on their own; sometimes knocking down the healthy cedars and Douglas-fir trees next to them.  By selecting the alder to remove and controlling the thinning, I think this project will help protect the existing conifers!

    I’ve also observed that the forest lacks trees in the understory. Creating a few gaps in the canopy will allow sunlight to reach the forest floor where trees and shrubs have been planted in recent years. It’s great that after the thinning is done they’ll be planting more trees and shrubs that are beneficial to wildlife. 

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