Sites P‑4 & P‑5

Approach

Last year, the Port Commission called for more community engagement before determining the removal and replanting approach for overheight trees on Port properties along S. 200th Street in the City of SeaTac (Sites P-4 and P-5). Most over-height conifers are located within the sites, and both are also adjacent to residential properties.

Using input submitted at a June 5 community workshop and through an online open house, the Port developed a preferred approach for sites P-4 and P-5 that reflects the community’s feedback. This approach, which was presented at the July 25 Port of Seattle Commission meeting, calls for removing only existing obstructions and preserving, to the extent feasible, all other trees and vegetation. Replanting work will re-establish a low-growing forest on-site with a neighborhood vegetation barrier and restore a tall-growing native forest just south of both sites. A key part of the approach will be to replace the invasive understory with native shrubs where possible. In some areas, the extent of the invasive plant cover will require the replacement of all vegetation.

 



Characteristics of Sites P‑4 & P‑5

 


Site P-4 Characteristics

3.7 acres | Dense invasive blackberry, English ivy, and holly

Site Native conifers Other Natives Non-natives and Snags Grand Total
P4 Obstruction 25 13 – 38
Potential Obstruction 48 9 – 57
Understory Trees – – –
P4 Total 73 22 – 95
Site P-5 Characteristics

5.1 acres | Dense invasive ivy and blackberry | Limited native salal

Site Native conifers Other Natives Non-natives and Snags Grand Total
P5 Obstruction 92 12 – 104
Potential Obstruction 20 10 – 30
Understory Trees 96 183 48 327
P5 Total 208 205 48 461

Removal Approach for Sites P‑4 & P‑5

Sequence Removal

Removal of Existing Obstructions (Protect Potential Obstructions and Understory)

Advantages

  • Sites are obstruction-free for 5 years
  • 30 to 40 tall conifers preserved for 5 years
  • Phased plant reestablishment
  • Preserves saplings, shrubs and vegetation to the extent feasible

Disadvantages

  • Site reentered every 5 years to remove obstructions as they occur
  • Repeated disturbance to the site may reduce success of replanting
  • Limited removal of invasive species



Replanting Approach for Sites P‑4 & P‑5

Create a Tall Forest

Replace Trees Onsite and Create a Tall-growing Forest Nearby (with a Vegetation Barrier)

Advantages

  • Large containers allow trees to mature faster
  • Prioritizes replanting of conifers
  • Removes invasive vegetation
  • Vegetation barrier for adjacent residences
  • Tall-growing trees

Disadvantages

  • Longer period to re-establish a low-growing forest onsite






Additional information Regarding Sites P‑4 & P‑5

Objectives

Port of Seattle’s Removal and Replanting Objectives for Sites P‑4 & P‑5:

  • Eliminate existing and potential obstructions
  • Minimize environmental impacts
  • Restore a diverse native forest community
  • Maintain a barrier between sites & adjacent neighborhoods
Public Input

What We Heard from the Public about Sites P‑4 & P‑5:

  • Stagger the tree removal to allow younger trees to mature
  • Protect and prioritize conifers
  • Remove invasive species
  • Maintain a barrier between sites & adjacent neighborhoods
Tree Size and Growth Comparisons

Initial Tree Size by Container Type

Short-growing and Tall-growing Trees Comparison

On-site Planting (e.g., Shore Pine)
Maximum height: 70 feet

Off-site Planting (e.g., Douglas Fir)
Maximum height: 200 feet

Summary Comparisons

Removal Alternatives Timeline

Replanting Options Summary

Larger  plantings Conifers Invasive Management Vegetation Barrier Tall-growing Trees
OPTION 1
Onsite planting		 ✓ ✓ ✓
OPTION 2
Onsite planting with vegetation barrier		 ✓ ✓ ✓ ✓
OPTION 3
Onsite & nearby planting		 ✓ ✓ ✓ ✓ ✓
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