Uplands and Slopes: South Plateau

Description

The South Plateau is an isolated upland with a separate, unofficial entrance. From the main body of the park, it is only accessible via a steep social trail that is slippery in the winter and friable in the summer. If you think of North Beach Park as a boot, the South Plateau is the heel. The floor of the plateau is surrounded by steep, short walls.

The South Plateau, at 25,000 square feet, is also the largest flat area in the park. As explained in “Park and Restoration History,” the South Plateau was intensively cleared in the summer of 2012 by an independent forest steward.

For more than a year, the only work done in the South Plateau was by Parks Department Natural Area Crew. In the summer of 2014, forest stewards watered and did some after care for the plants in June and July, and there was a work party in September.

The South Plateau has less than 1% conifer cover, but at least 75% deciduous cover.

The target forest type for the South Plateau is Tsuga heterophyllaPseudotsuga menziesii/Polystichum munitumDryopteris expansa (Western hemlock – Douglas fir/Sword fern – Spreading wood fern; TSHE-PSME/POMU-DREX). The reference ecosystem is Mesic-moist conifer and conifer-deciduous mixed forest.

Water Flow

During the rainy season, water accumulates from NW 85th St. and 26th Ave NW (310 feet) (all elevations from Seattle DPD GIS map). It runs to the north uninterrupted by any green scape or drainage system the length of 26th Ave. to 88th St., where it turns to the west. Once at 27th Ave., it turns again to the north and enters the park. The floor of the South Plateau is at 250 feet, giving this run about a 5% grade.

Figure 1: Path of water flow into the South Plateau.

The blue line indicates path of water, which flows toward the top of the map, from 85th St. to the South Plateau. (Source: Seattle Department of Public Development DPDGIS map.)

The blue line indicates path of water, which flows toward the top of the map, from 85th St. to the South Plateau. (Source: Seattle Department of Public Development DPDGIS map.)

Before clearing, the dense ivy and blackberry cover dissipated a lot of the energy of this water flow, spreading it out over the surface of the plateau. However, invasive removal caused a serious erosion problem was caused.

The Parks Department has installed rip rap and forced meanders into the water flow using plantings and fascines (water barriers made of bundles of salmonberry live stakes).

Figure 2: Water flow in May, 2014

Looking up towards the entrance of the park (the gray rocks in the upper right.) This is from about the middle of the fascines.

Looking up towards the entrance of the park (the gray rocks in the upper right.) This is from about the middle of the fascines.

There is still some water flow control to be done on the South Plateau, and it will have to be studied during rain events of different sizes during the fall and winter.

Water control can be improved in this area by adding meanders to the downstream end of the storm runoff, maintaining the existing meanders and fascines, and working with the stream to slow it down and let the water percolate through the plateau.

During the summer drought, the South Plateau has no water source. This leads the soil to dry and harden, becoming very compact. Plant establishment is very slow, but improving.

For more recent observations on South Plateau water issues, please see Water Flow: South Plateau Street Runoff.

Vegetation

At the start of restoration, the South Plateau was a mix of Acer macrophyllum (Big leaf maple) and Alnus rubra (red alder), with a shrub layer almost exclusively of Hedera helix (English ivy) and Rubus armeniacus (Himalayan blackberry). Other notable invasives included Lamium galeobdolon (Yellow archangel) and Clematis vitalba (Wild clematis).

There is still a fair amount of remnant and resurgent Hedera helix (ivy). Calystegia sepium (bindweed), Lapsana communis (nipplewort), and Geranium robertianum (herb robert) have also made inroads.

A forest monitoring plot following the Green City protocol was established in the South Plateau in July, 2012, and revisited in August, 2013. Note the difference, in Figures 3 and 4 below, in regenerative invasive trees. This is what happens with overclearing followed by neglect.

Figure 3: Invasive regenerative trees, South Plateau, 2012.

This was the extent of invasive trees in 2012, when the South Plateau was just starting to be cleared. (Source: EarthCorps, 2012)

This was the extent of invasive trees in 2012, when the South Plateau was just starting to be cleared. (Source: EarthCorps, 2012)

Figure 4: Invasive regenerative trees, South Plateau, 2013.

The South Plateau was cleared aggressively in 2012 and early 2013, and then neglected.

The South Plateau was cleared aggressively in 2012 and early 2013, and then neglected.

Invasive Removal and Restoration Plan

Figure 5: South Plateau.

A: Accessible to volunteers. B: Contract or Natural Area Crew. (Source: GSP Reference Map on ArcGIS.com)

A: Accessible to volunteers. B: Contract or Natural Area Crew. (Source: GSP Reference Map on ArcGIS.com)

Subarea A

Subarea A (outlined in blue in Figure 5, above), at 13,000 square feet, is the largest and driest flat area of the park and the most volunteer friendly. Even though it’s surrounded by Subarea B, it can be accessed by walking carefully down some rip rap. This was the area the independent forest steward and her crew worked in.

The over-clearing followed by neglect has left the South Plateau with a plant community that is still very much out of balance. It’s in better shape than when the ivy and blackberry dominated, but it’s still at risk of an invasive-only plant community.

There is still a lot of invasive removal in Subarea A, including annuals such as Lapsana communis (nipplewort). Subarea A could use a lot of wood mulch, both around the establishing plants, and in large areas of relatively bare ground. In the long term, this would ease the compaction of the soil and aid in plant establishment.

Suggested tasks for Subarea A:

  • Mulch around existing plants, and spread mulch to a depth of at least 4” in bare areas of South Plateau.
  • Monitor water flow during rain events. Adjust and repair fascines as necessary.
  • Add meanders to further reaches of South Plateau. The goal is to slow and spread the water, so it stays on the South Plateau and percolates into the soil.
  • Investigate mycelium inoculation as a means of improving soil conditions.
  • Forest stewards continue working in South Plateau one day a month for after care and weeding.
  • Have two work parties a year (one for planting, one for invasive removal and/or after care).

Subarea B

Subarea B is the walls surrounding the plateau part of the South Plateau. It measures approximately 12,000 square feet. The walls are nearly vertical, making it only available for work by the Parks Department Natural Area Crew. There is a rim of the plateau accessible from 27th Ave NW, but it is so narrow that the best approach is to have the Natural Area Crew work on the rim, and the forest stewards or volunteers do aftercare.

Either the Parks Department Natural Area Crew or the volunteers in the summer of 2012 (or both) have done some work on the western slope. On the eastern and southern slopes of the wall, property lines might be an issue.

Further work on Subarea B will be done by the Parks Department Natural Area Crew. Some of the work could be done at the same time as working on the South or West Slopes (see below).

Suggested tasks for Subarea B:

  • Remove resurgent invasives and increase density in cleared areas.
  • Remove ivy and put survival rings on trees on the northern edges of the South Plateau.
  • Coordinate work on the northern edges of the South Plateau with work done on the South Slope.

References

Department of Planning and Development. 2007. City of Seattle Department of Planning and Development GIS map. http://web1.seattle.gov/dpd/maps/dpdgis.aspx (Dates of accession various.)

EarthCorps. 2012. North Beach Park South Plateau Baseline Report. (unpublished document). EarthCorps, Seattle.

EarthCorps. 2013. North Beach Park South Plateau Monitoring Report. (unpublished document). EarthCorps, Seattle.

Green Seattle Partnership, 2014. GSP Reference Map on ArcGIS.com. http://www.arcgis.com/home/webmap/viewer.html?webmap=9be9415001144aa383e5b86e481d2c45&extent=-122.5312,47.374,-121.7945,47.7577 (Dates of accession various.)

North Beach Park Week in Review

It’s been a busy week at North Beach Park!

It started last Sunday (16th), when Friends of North Beach Park forest steward Morry (who also works at Llandover Woods) arranged for the forest steward from Llandover, Glenn, to bring some equipment to North Beach Park so we could shoot a video.

Drone
Here is a picture of one of the drones being stabilized before takeoff.

And here is the resultant video:

NorthBeachNovember1080 from Glenn Austin on Vimeo.

I recommend full screen, of course. And turn off any other music so you can hear the wonderful guitar piece Glenn selected for the video.

Making the video was fun, and the results certainly can’t be beat. Now I want to do one every season — easy for me to say, of course, I don’t have to do any of the work. ;> (There are more photos on Flickr.)

Here is a video Glenn made of Llandover Woods.

On Monday, Drexie, Tad, and Luke prepared the plants for the work party. This involved sorting, revising the planting plan, figuring out which was which and what was what, and tagging everything.

Here are Tad (left) and Drexie (center background) tagging the plants:
Tad (left) and Drexie (center background) tagging plants

We took the plants to North Beach and left them in a staging area down the trail. We also saw, much to our dismay, that someone — between Sunday afternoon and Monday morning — dumped at least 43 cans of paint in North Beach Park. The ones I picked up were all full. The Ballard blog posted an article about it. It’s nice to see that most of the comments are upset about the dumping.

The paint cans were pretty quickly picked up, probably Tuesday (thank you, Seattle Parks Department!). But still, considering where they were, someone went to more trouble to dump them in the park than it would have taken to get rid of them legitimately. (Guess what — more photos on Flickr.)

And Saturday was our planting party. In addition to the plants from the Green Seattle Partnership, we had eight Sitka Spruce and one Western Red Cedar provided by a neighbor.

We had help from the iCARE students from North Seattle College again:
iCARE

And we were also joined by students from Circle K International from the UW:
Circle K International

We planted more than 100 plants, and this included a fair amount of prep work for some of the areas. It was a very successful work party.
Plants ready for installation

Our next work party won’t be until January. But there are still work parties at Golden Gardens, Carkeek Park, and Llandover Woods.

November Work Party!

November is the second of FOUR planting work parties in North Beach Park. We hope to plant just over 1000 plants (total). Join us for this quest and help make North Beach Park even better.

Saturday, November 22: We’ll be working in an area that was cleared last winter. Now it needs some extra attention before being planted, so this will be a mixture of a work party. We’ll clear the area first and then plant – 72 plants. It all should go rather quickly.

We’ll meet at 9 a.m. at the main entrance to the park, 90th St. and 24th Ave. NW. We’ll go until 12 noon.

At this work party, Friends of North Beach Park will be joined again by students from North Seattle’s iCARE program for international students, and students from the University of Washington Circle K International.

Please sign up in advance so we know you’re coming.

Remember to wear weather-appropriate layers that can get dirty and bring water or a snack if you need them. We provide tools, gloves, and guidance. All ages are welcome; volunteers under 18 must sign and bring a waiver (available online). The #40 and #48 buses stop within a few blocks of the park, check Metro for details. Parking is available on 90th St. east of 24th.

November 22 will be the first of two planting work parties installing plants provided by Green Seattle Partnership and Seattle Department of Parks and Recreation. On January 24, we return to the South Plateau for more GSP plant installation. The last planting work party will happen on February 28, when we install shrubs and small trees in the wetlands provided by the Washington Native Plant Society stewardship grant.

As always, if you don’t have the time to join us for a work party, you can support Friends of North Beach Park by making a directed donation to the Seattle Parks Foundation.

All money donated will be used to fund the restoration efforts of North Beach Park.

If you have any questions, feel free to write lukemcguff[at]yahoo.com for further information.

Water flow: South Plateau Street Runoff

(This the first of two posts about street runoff in North Beach Park.)

There are two ways that water enters North Beach Park. The main way, which lasts all year long, is by numerous, broad, horizontal groundwater seeps. Most of these come into the park from the south wall of the ravine; some enter the park from the base of the 24th Ave. slope. These provide a steady flow that has lasted through record droughts. The seeps move very slowly, and do not form channels.

The other way water enters the park is through flashy events triggered by rainstorms. We’re still investigating these water flows. This water enters the park from two locations, the South Plateau and a culvert from 24th Ave. located at the southeast corner of the park.

The first we knew of is the water flow from the South Plateau. The water accumulates for several blocks before it enters the park; by then, it is a narrow, fast flowing stream. Before the South Plateau was cleared, this water hit a dense mat that was a mixture of blackberry and English ivy. It might be that this dense mat dissipated the energy enough to avoid channelizing and erosion.

In the summer of 2012, volunteers cleared the South Plateau in a series of weekly work parties. They also installed a stairway, hoping to create a native plant demonstration garden. The stairway was at the very point that the street runoff entered the park. When we found out how much water was flowing into the park, the project was abandoned and the South Plateau was neglected by forest stewards until the summer of 2014.

Street Runoff
The photo above is from October, 2012, and shows the runoff sheeting over the steps.

South Plateau Street Runoff
The photo above is from December, 2012. You can see how straight the channel is already. There had been little planting so far, and no attempt had yet been made to control or slow the water.

In the spring and summer of 2013, Parks Department crews installed rip rap at the entrance to the park. They dismantled the staircase and replaced it with a series of coir logs forming terraces. Past the rip rap and the coir log terraces, the crews installed meanders and fascines into the channel, to slow the water down and give it more opportunity to percolate into the soil.

On October 31, 2014, two forest stewards (Luke and Tad) visited the South Plateau at the tail end of a rain storm. It had rained nearly 1 3/4″ in the previous 36 hours according to a rain gauge in Tad’s back yard. This part of the post incorporates Tad’s notes from our visit.

Most of the street runoff was flowing into the park via the rip rap. Some flowed past the rip rap and was absorbed by a large wood chip pile. (However, this is a temporary feature.)

Street runoff
The above picture shows the flow as the rain was tapering off. The flow is much slower for various obstructions and meanders, but does not stay on the plateau long enough to sink in.

Street runoff
At the west end of the plateau, the water runs underneath some wattles the three of us installed in May. It flows down to the main body of the park. We still need to observe the runoff in the main body of the park during a heavy rain.

Standing water
We also saw standing water or slowly moving water in many places in the South Plateau that were relatively far from the street runoff channel. Is there a clay layer near the surface? Is there something else that prevents water from percolating into the soil?

We still need to explore the South Plateau and North Beach Park during heavy rain. There are a couple places where we might be able to divert the street runoff to flow over the plateau and sink in before flowing over the edge. We also need to understand where the pooling water is coming from: Another runoff we don’t know about yet, or just rainfall?

Wetlands: Stewardship Grant

In June of 2014, Friends of North Beach Park received a $500 stewardship grant from the Puget Sound Chapter of the Washington Native Plant Society.

The main body of this chapter was written in summer of 2014. The “Addendum” section, following “Plant List” below, was written in November 2014, after some work had been done.

Purpose of grant

The purpose of the grant is to help rebuild the wetland basins of the park into a scrub-shrub plant community, with trees surrounding the wetlands to stabilize the upland slopes. The planting pallet will follow recommendations for the reference ecosystem, riparian forest and shrubland.

The replanting will be done in phases, using obligate wetland plants to begin holding the soil, followed by reintroducing woody plants to build deeper root structures.

Timeline (projected)

The timeline below was written in summer of 2014.

  • September: Invasive removal in the wetlands. This will be done by small groups of forest stewards. Care will be taken not to overclear an area and not to disturb the soil structure too much.
  • Early October: installation of obligate wetland plants. This is done just prior to rain return, so the ground is relatively stable. The work will be done by experienced forest stewards.
  • Late October: installation of facultative shrubs and woody plants at the wetland borders. This work can be done by volunteers during a regular Friends of North Beach Park work party.

For the timeline as the project is being executed, please see “Addendum,” below.

Plan

The work will be centered on the social trail dividing Headwaters Bowl Subarea B and Central Valley Subarea B. See Figure 1, below.

Figure 1: Area of work for the Stewardship Grant.

The projected work area for the WNPS Stewardship Grant.

The projected work area for the WNPS Stewardship Grant.

The stream will be the northern boundary. In the Central Valley, the southern boundary will be the south loop social trail. In the Headwaters Bowl, the southern boundary will be the wetland border established by Doug Gresham in 2011. This is the entire area referred to as “Central Valley Subarea B” and the western edge of the area referred to as “Headwaters Bowl Subarea B.” The actual work area will be smaller than illustrated above.

The planting is intended to increase diversity and density in three locations:

  • Mixture of shrub and herbaceous plants streamside.
  • Herbaceous plants in seeps.
  • Shrubs at the toe of the slopes, above the seeps.

Headwaters Bowl Subarea B

Streamside

The substrate of the stream in this location is mostly silt and fine sand, with occasional patches of small cobbles where the channel has narrowed.

There is a large Thuja plicata (Western red-cedar) stump in the stream, covered with moss and hosting numerous Vaccinium parvifolium (Red huckleberry). This could host some Cornus canadensis (Canadian dwarf dogwood) but would be unlikely to support Tsuga heterophylla (Western hemlock).

Plants already growing streamside (based on a visual survey):

  • Rubus spectabilis (Salmonberry)
  • Lysichiton americanum (Skunk cabbage)
  • Oenanthe sarmentosa (Water parsley)
  • Carex amplifolia (Broad-leafed sedge)
  • Polystichum munitum (Sword fern)
  • Athyrium filix femina (Lady fern)
  • Urtica dioica (Stinging nettle)
  • Sambucus racemosa (Red elderberry)
  • Tolmeia menziesii (Piggyback)
  • Cardamine hirsuta (Shotweed)
  • Lonicera involucrata (Twinberry)

Above the stream

About five feet above the stream, there is a nurse log and a large amount of coarse woody debris holding the stream bank. I think the seep is eroding the soil from underneath the CWD, and it will eventually collapse. Upland of this the substrate is mostly decayed wood, which makes it a good place for Tsuga heterophylla. On either side of this substrate, the seeps reach to the wall of the ravine.

Growing in this area:

  • Polystichum munitum (Sword fern)
  • Rubus spectabilis (Salmonberry)
  • Ilex aquifolium (Holly)
  • Hydrophyllum tenuipes (Pacific waterleaf)
  • Tolmeia menziesii (Piggyback)
  • Sambucus racemosa (Red elderberry)
  • Ribes bracteosum (Stink currant)
  • Spiraea douglasii (Douglas’ spirea)
  • Germanium robertianum (Herb robert)

Growing in the seep between the CWD area and the social trail:

  • Tolmeia menziesii (Piggyback)
  • Glyceria elata (Tall mannagrass)
  • Oenanthe sarmentosa (Water parsley)
  • Hydrophyllum tenuipes (Pacific waterleaf)
  • Rubus spectabilis (Salmonberry) in dryer areas
  • Thuja plicata (Western red-cedar) (planted)
  • Cardamine hursuta (shotweed)

Central Valley Subarea B

Streamside

The stream itself is similar to the stream in HWB Subarea B: The wider sections have a substrate of sand and fine silt, and with narrower sections have a substrate of small cobbles.

The red cedar stump in this section has a wider variety of plants than the one in the HWB section. In addition to the red huckleberry and mosses, there are also salmonberry and a Tsuga heterophylla (Western hemlock) seedling that is naturally regenerating.

Above the Stream

There is also a nurse log holding the bank, but there is not the woody debris substrate above it as with the HWB.

Salmonberry and red elderberry form a thicker canopy than on the HWB side. There is also much more Hedera helix (English ivy) that comes down from the South Slope and lies across the seeps.

In the stream, but closer to the right bank, is a red alder root ball, with the tree itself lying across the width of the seep. The root ball has red huckleberry, ivy, and a couple Acer macrophyllum (Big leaf maple) seedlings growing in it. There is holly in the stream and around the root ball that will need to be removed.

Integrating into Work Flow

Between Sept. 15 and Nov. 27, there are nine possible Monday sessions and the October work party. The September work party will be on the South Plateau, and the November work party will be dedicated to planting GSP-provided plants. It is possible that some work on the stewardship grant could take place at the November work party.

Plant list

Table 1, below, is the plant list submitted to the WNPS for the grant. The actual planting list will vary considerably from this list, but that variance is within the scope of the grant. The wetland status, size, and number were obtained from the Fourth Corner Nurseries Catalog.

Table 1: Plant list and estimated planting time.

Early October
Genus Common Name Wetland Size # plants
Carex deweyana Dewey’s sedge FAC bareroot 100
Carex obnupta Slough sedge OBL bareroot 100
Fraxinus latifolia Oregon ash FACW 6-12″ 50
Glyceria elata Tall mannagrass FACW bareroot 100
Viburnum opulus v. americanum Highbush cranberry FACW 3-6″ 50
Late October
Genus Common Name Wetland Size # plants
Holodiscus discolor Ocean spray FACU 6-12″ 50
Lonicera involucrata Black twinberry FAC 6-12″ 50
Berberis nervosa Low oregon-grape FACU 3-6″ 100
Sambucus racemosa Red elderberry FACU crown 50
Vaccinium parvifolium Red huckleberry FACU 2″ pots 50

OBL = obligate, plant has to grow in a wetland; FACW = facultative wetland, plant grows in a wetland most of the time but can occasionally be found in drier areas; FAC = facultative, plant grows equally well in wetlands and drier areas; FACU = facultative upland, plants grows mostly in drier areas, but can occasionally be found in wetlands.

For the purchased plant list and the actual planting times, please see “Addendum,” below.

Addendum

This is the revised timeline, written after some work had already been done.

  • Plants were ordered in October for October and February delivery.
  • The October plants were wetland obligate graminoids.
  • The February plants were facultative wetland shrubs and trees.
  • The plants will be installed during regular public work parties.

In October 2014, the following orders were placed with Fourth Corner Nursery, for delivery in October and February.

Table 2: October order of Obligate plants.

Scientific Name Common Name Wetland Quantity
Carex amplifolia (1) Broad-leaved sedge OBL 50
Carex stipata (2) Sawbeak sedge OBL 100
Deschampsia caespitosa (3) Tufted hair-grass FACW 50
Glyceria elata (1) Tall mannagrass FACW 100
Juncus ensifolius (2) Daggerleaf rush FACW 50
Scirpus microcarpus (3) Panicled bulrush OBL 100

1 = observed growing with limited distribution; 2 = introduced to North Beach Park with this planting; 3 = previously introduced by restoration planting.

Table 3: February order of Facultative Wetland Shrubs and Trees.

Scientific Name Common Name Wetland Quantity
Physocarpus capitatus (3) Pacific ninebark FACW 50
Fraxinus latifolia (1) Oregon ash FACW 50
Malus fusca (2) Pacific Crab Apple FACW 50
Salix lucida (2) Pacific willow FACW 50
Salix sitchensis (2) Sitka willow FACW 50

1 = observed growing with limited distribution; 2 = introduced to North Beach Park with this planting; 3 = previously introduced by restoration planting.

The October order is the actual quantities delivered and planted during the October work party. As discussed above, the work occurred in the Central Valley Subarea B and Headwaters Bowl Subarea B.

The planting was done by volunteers led by forest stewards. Duckboards were used to minimize disruption to the wetlands wherever possible.

The work area actually became larger than illustrated in Figure 1, above. Planting was done further east in Headwaters Bowl.

The second order will be delivered in time for the February work party (February 28, 2015). Approximately ten of each shrub will be held back for a year or so, to test is survival rates are increased with an extra year of nursery care.

The second planting will also happen further east than the original prospect in Figure 1.

Green Seattle Day This Saturday!

2014 Green Seattle Day

Your forest needs you! Join the Green Seattle Partnership on Saturday, November 8th, as we kick off planting season with a day of volunteerism in 21 parks throughout the City at the 9th Annual Green Seattle Day.

Our biggest event of the year, Green Seattle Day is a great chance for first-time and long-time volunteers to help grow the forest in their own city by planting trees and other plants in city parks. This year our main site will meet at the Rainier Beach Community Center (lunch included after planting), but there are 17 other locations around the city that need volunteers, so check out the full list here, pick your lucky park, and sign sign up now so that we can plan the best event for everyone.

To join us at the main site, sign up to volunteer at the East Duwamish Greenbelt, Kubota Gardens, Lakeridge Park, or Rainier Beach Urban Farm & Wetlands, and meet at the Rainier Beach Community Center at 9am.

The Ballard park hosting Green Seattle Day this year is Golden Gardens. Join forest stewards from Carkeek Park, North Beach Park, and of course, Golden Gardens to spruce up the place a little bit.

Salamander
[Photo from Green Seattle Day 2013 at Carkeek Park.]

Green Seattle Day is great for all ages. We’ll bring the gloves, tools, and all of the plants, you bring the helping hands! Coffee and snacks provided at all sites, so register early so that we can have enough for everyone. Please dress for the weather, and wear sturdy shoes that can get wet and a little dirty. This is our biggest party of the year and we want you there! More information available at www.greenseattle.org. Please contact Norah Kates at info@greenseattle.org, or call (206) 905-6943 with any questions.

Thanks, and we look forward to seeing you in the parks!

State of the Park and 2015 Plans

A bulleted list! So you know it’s precise! Considering each HMU where we did some work in 2014, starting with the South Plateau:

South Plateau

  1. Had been neglected since project dropped by previous forest steward.
  2. Neighbor complaints caused us to return to working on it.
  3. Water flow appears to be under control. One forest steward has examined it in the rain and observed that most of the water was flowing into a wood chip pile.
  4. Personal contact was made with two neighbors of the South Plateau, and a homeowner engaged in a gutting and refurbishing of a house. All contacts were positive.
  5. There was one work party in 2014, clearing and planting prep with SPU students.
  6. Issues:
    • Ivy, holly, blackberry, yellow archangel resurgence.
    • Nipplewort, wall lettuce, other annual weeds.
    • Water flow seems to be under control, but still needs to be inspected regularly during heavy rain.
    • Establishment and after care for already established plants.
    • Maintain neighbor relations.
  7. 2015 Plans:
    • January: Planting work party, 128 plants.
    • September: Clearing and prep for planting with SPU students.
    • Forest stewards will continue to work approximately one Monday a month, to maintain cleared areas and prevent reinfestation. We will also attempt to spread seeds of native plants as appropriate, particularly Dicentra Formosa (Pacific bleeding heart).

Central Valley:

  1. Began 2014 with clearing about 800 square feet, down the trail from Knotweed Hill. The clearing happened on both sides of the trail, so it was in both the Central Valley and on the base of the 91st St. Slope.
  2. The area was neglected during the summer months in favor of after care for plants in drier areas of the park – along the North Slope side of the main trail and along the 24th Ave. rim.
  3. A three person crew worked on the area during the August work party.
  4. This area will be planted in the November work party. There will be enough people there to do some clean up first.
  5. Extensive planting happened in the seeps at the eastern edge of the Central Valley during the October work party.
  6. 2015 plans: Forest stewards and work parties will monitor cleared areas to prevent invasive resurgence and provide after care as/if necessary.

91st St. Slope:

  1. In addition to the clearing mentioned above, a thicket of laurel was limbed by forest stewards early in the summer.
  2. This thicket was given both E-Z-Ject and cut and paint treatments to kill the laurel.
  3. Forest stewards will monitor this laurel thicket.

Knotweed Hill (Knotweed Hill is located at the border of the North Slope and the 91st St. Slope HMUs.)

  1. Knotweed Hill was treated for knotweed in the summer of 2014.
  2. There was some watering of the upland plants in the summer, but it has received no other attention.
  3. It needs to be monitored for invasive resurgence and any after care.

Headwaters Bowl (“HWB”):

  1. The narrow, western section of the HWB received about half the plants from the October work party. Some plants were put into bowl section as well.
  2. The area between the north side of the streambank and the main trail received a lot of clearing in 2013 from EarthCorps and Parks Dept. contract crew. These cleared areas need to be regularly inspected to prevent resurgence and to provide after care for plants installed in 2013.
  3. An area of the HWB that has received little attention so far was transected by two forest stewards (Luke and Drexie) in October. We started at the Two Cedars area (about 150 feet down the main trail) and crossed the HWB just west of a line of old Alnus rubra (red alder).
    • North of the stream, we saw a large number of small Vaccinium parvifolium (red huckleberry). It was unclear whether they were planted or volunteers.
    • Immediately south of the stream crossing the soil was very wet and marshy. There were many large Lysichiton americanum (skunk cabbage) leaves dying back. There was also evidence of Equisetum arvense (horsetail) from earlier in the season.
    • Further south of the stream crossing, the ground rose slightly and was dryer. At that point, the Rubus spectabilis (salmonberry) became very thick.
    • There was some Polystichum munitum (sword fern) and Athyrium filix femina (lady fern), but ground cover in general was relatively sparse.
    • There was a thicket of Ribes bracteosum (stink currant) at the border of the wet and dry areas.
    • At the base of the south slope we stopped to write down what we’d seen so far. In addition to the already mentioned plants, there were:
      • Emergent (that is, taller than the shrub layer) Acer macrophyllum (big leaf maple) and Alnus rubra (red alder).
      • Sambucus racemosa ssp. pubens (red elderberry) thicket.
      • Sorbus aucuparia, European ash.
      • An apparently dead Populus balsamifera (cottonwood) stake from 2012.
    • Going up the south slope to the houses, we saw:
      • Sword fern as dominant groundcover.
      • Occasional salmonberry, but fairly isolated and lower on the slope. Otherwise, no shrub layer to speak of.
      • Big leaf maple trees dominant towards the middle of the slope, with conifers along the rim (we weren’t able to identify the conifers from that distance).
    • We continued east along the base of the south slope towards the 24th Ave. Slope.
      • Outside of the tree cover, the ivy was very dense, bushy, and had many many seed pods.
      • There were a couple small Thuja plicata (Western red-cedar) that Tad and Luke had liberated from salmonberry in 2012; Luke and Drexie liberated them again.
      • The base of the 24th Ave. rim was dominated by Hedera helix (English ivy), with Urtica dioica (stinging nettle) growing up between it. There was no shrub layer and no regenerating trees.
      • The culvert that empties into the park from the corner of the 24th Ave. slope and the south slope has gouged a deep channel. There is a lot of construction rubble in the channel, but also some large garbage (garbage cans, tires, etc.) that should be removed. This is on private property, but if at all possible it should get treated with some rip rap. The channel is still carved farther down, and at the base of the slope and in the flat area it can receive fascines or woody debris.
  4. For 2015, we will work with the Parks Department to determine what can be the scope of volunteer work in the private property areas of the HWB, and then contact the neighbors to get permission for that work.

Wetlands: Central Valley

The Central Valley is the area in light green (planting) and pale yellow. The blue line is the stream. (Source: GSP Reference Map on ArcGIS.com.)

The Central Valley is the area in light green (planting) and pale yellow. The blue line is the stream. (Source: GSP Reference Map on ArcGIS.com.)

At 1.97 acres, the Central Valley (“CV”) is the largest HMU in North Beach Park. Its northern border is a stream crossing; its eastern border is the main social trail; its southeastern border is a stream crossing and the start of the south loop social trail; its western border is the south loop social trail. The gradient between the eastern side of the central valley and the main social trail varies from almost nothing to very steep. The gradient between the south loop social trail and the floor of the valley is very steep throughout.

The slopes of the valley are heavily invaded, but explorations of the middle of the valley reveal an area not in such bad shape. The Rubus spectabilis (salmonberry; RUSP) layer of the canopy is so dense that it makes exploration very difficult. In the summer of 2014, we did a belt transect through the widest part of the CV; please see “Vegetation” below for a discussion of the results of the transect, and “Belt Transect” in “Monitoring” for a discussion of the protocol.

The tree canopy percent cover for the CV is 60% deciduous, almost exclusively Alnus rubra (Red alder). There is less than 1% coniferous cover, Thuja plicata (Western red-cedar), located in the southwest corner. There is about 5% cover of regenerating deciduous trees, and less than 1% of regenerating coniferous trees. The CV has the largest canopy gaps in the park, allowing Calystegia sepium (bindweed) to establish in the sunlight.

The reference ecosystem and target forest type for the CV are the same as for the Headwaters Bowl: “riparian forest and shrubland” for the ecosystem and ALRU/RUSP/CAOB-LYAM (Red alder/salmonberry/slough sedge – skunk cabbage) (Chappell 2006) for the target forest type.

The existing plant community is ALRU/RUSP (Kunze), and the soil is correspondingly relatively dry. The saturated areas of the CV are much smaller than those in the Headwaters Bowl.

The RUSP layer is so dense that it forms a closed canopy and prevents any other shrubs or trees from establishing. The most noticeable groundcover under the RUSP canopy is Tolmiea menziesii (Piggyback) and Hedera helix (ivy). Care must be taken during restoration not to disrupt the RUSP canopy lest the ivy take off.

The southeastern section of the CV (part of Subarea A, below) is in phase one of restoration, invasive removal. See “Monitoring Protocols and Success Metrics.”

As with the Headwaters Bowl, the CV is split into four sub areas, depending on who can do the work or the technique for best restoration. See “Invasive Removal and Vegetation Plan,” below.

Water Flow

Again, as with the Headwaters Bowl, most of the water flow in the Central Valley is from the southern wall of the park towards the stream channel. The water appears to be more channelized than in the HWB; perhaps this is because the RUSP canopy provides greater soil control.

Vegetation

1/10th Acre circular monitoring plot

There was one 1/10th acre circular forest monitoring plot established in the south eastern corner of the Central Valley (Subarea B). Please see “Green City Monitoring Protocol” in “Monitoring Protocols” for a discussion of this protocol. The baseline monitoring was taken in September 2011, and the plot was revisited in August 2012. As with the HWB plot (above), percent cover was determined by consensus of the people doing the surveying, and reported in broad categories for city-wide consistency.

2011 invasive groundcover for Central Valley monitoring plot.

2011 invasive groundcover for Central Valley monitoring plot.

2012 invasive cover in Central Valley monitoring plot.

2012 invasive cover in Central Valley monitoring plot.


Key: Groundlayer and shrub percentages are for percent cover. Tree density is trees per acre. Red bar indicates immediate attention needed; light orange bar means attention needed soon. Source: EarthCorps, 2011 and 2012.

The figures below compare native groundlayer change between 2011 and 2012. Note in particular the return of Hydrophyllum tenuipes (Pacific water leaf) and Lysichiton americanum (skunk cabbage) both of which returned from the seed bank.

2011 native groundcover in the Central Valley monitoring plot.

2011 native groundcover in the Central Valley monitoring plot.

2012 native groundlayer cover in the Central Valley monitoring plot.

2012 native groundlayer cover in the Central Valley monitoring plot.

Belt transect

In the summer of 2014, a cross-gradient belt transect was done in North Beach Park that crossed the Central Valley along the 90th St. right of way. Eight 4’x16’ plots were established in the Central Valley. The transect went from west to east, through subareas C, D, and A.

The following table lists the target forest type species for the Central Valley, all the species found in the belt transect, their percent cover across the entire transect, and what the percent cover of their TFT goal is. Percent cover was determined by one person consistently, and is given in specific amounts. Please see the key below the table for a full explanation of the numbers.

Scientific Name Common Name Pct. Cover TFT Goal
Acer circinatum Vine maple 0.00 4.00
Acer macrophyllum Big leaf maple 26.11  
Alnus rubra Red alder 32.22 93.00
Angelica genuflexa Kneeling angelica 0.00 20.00
Athyrium filix-femina Lady fern 2.44 4.00
Atrichum selwynii Crane’s-bill moss 0.33  
Calystegia sepium false bindweed 0.33 0.00
Carex amplifolia Bigleaf sedge 0.89  
Chrysosplenium glechomifolium Pacific golden saxifrage 0.00 15.00
Circaea alpina Enchanter’s nightshade 0.00 3.00
Dryopteris expansa Spiny wood fern 0.22  
Equisetum telmateia Giant horsetail 2.22  
Erhythranthe guttata Yellow monkey-flower 0.00 4.00
Hedera helix English Ivy 14.28 0.00
Hydrophyllum tenuipes Pacific waterleaf 3.33  
Ilex aquifolium Holly 3.00 0.00
Lysichiton americanum Skunk cabbage 5.22 30.00
Moss   0.44 20.00
Mycelis muralis Wall lettuce 0.06 0.00
Oenanthe sarmentosa Water parsley 0.67 6.00
Oxalis oregana Oregon oxalis 0.00 8.00
Picea sitchensis Sitka spruce 0.00 8.00
Poa trivialis Rough-stalk bluegrass 0.00 30.00
Polystichum munitum Sword fern 3.06 6.00
Prunus laurocerasus Cherry laurel 0.39 0.00
Ranunculus repens Creeping buttercup 0.33 0.00
Ribes bracteosum Stink currant 0.11  
Rubus armeniacus Himalayan blackberry 0.67 0.00
Rubus spectabilis Salmonberry 53.89 57.00
Sambucus racemosa Red elderberry 0.44  
Stachys chamissonis var. cooleyae Coastal hedgenettle 0.00 4.00
Stachys mexicana Mexican hedge-nettle 0.00 4.00
Tolmiea menziesii Piggyback 2.17 34.00
Urtica dioica Stinging nettle 2.72

Key: “0.00” in Pct. Cover column indicates a target forest type indicator species not found during the survey. No value in the TFT Goal column indicates a native species not listed in the target forest type. “0.00” in the TFT Goal column indicates an invasive species to be removed.

Plots 4 through 10 of the transect were on the floor of the Central Valley. The following chart illustrates the relationship between density of salmonberry and red alder cover and ivy. How this will affect restoration is discussed in “Subarea D,” below.

Interaction of Salmonberry, Red alder, and English ivy.

Interaction of Salmonberry, Red alder, and English ivy.

Invasive Removal and Restoration Plan

There are four distinct subareas to the Central Valley.

North is to the top. A: All volunteers can work here. B: Forest stewards and experienced volunteers. C: Parks District Natural Area Crew (slope). D: Forest stewards and experienced volunteers.

North is to the top. A: All volunteers can work here. B: Forest stewards and experienced volunteers. C: Parks District Natural Area Crew (slope). D: Forest stewards and experienced volunteers.

Subarea A

Subarea A (outlined in blue above) measures approximately 17,350 square feet. It lies between the social trail and the stream and is relatively flat and accessible. A holly thicket was cleared from the southeastern portion in 2011. The ground returned with Hydrophyllum tenuipes (Pacific waterleaf) and was replanted with shrubs and ferns in the subsequent planting seasons.

The dark green section of Subarea A (approximately 9,600 square feet) was cleared and planted by EarthCorps volunteers in 2013. This work will be extended and monitored by the Friends of North Beach Park. In January 2014, Friends of North Beach Park cleared about 800 square feet of black berry past the north end of the dark green section of Subarea A. This received some Deschampsia cespitosa (Tufted hair grass) and Fraxinus latifolia (Oregon ash) in March that has established well. Ribes bracteosum (Stink currant) is spreading into the cleared area from nearby. The clearing did not reach the streambank because the ground was still very wet.

Work in Subarea A can be done by any volunteers or forest stewards. Parks Department Natural Area Crew will be requested for large laurel and holly removal.

Care must be taken working close to the stream to not disrupt the streambank. A section of Subarea A lies across the trail from an area called Knotweed Hill. This area should receive extra attention and monitoring.

Suggested tasks for Subarea A:

  • Plant newly cleared area in Fall of 2013.
  • Work with Parks Department crews to eradicate the holly and laurel.
  • Monitor invasive resurgence and native establishment in the Earthcorps-cleared areas.
  • Connect the cleared areas.

Subarea B

Subarea B, outlined in red above, measures approximately 4,800 square feet. It is a large, active seep with water flowing from the south wall of the ravine. The soils are permanently saturated and can bear little or no walking. The ground is too wet for all but such obligate plants as Oenanthe sarmentosa (Water parsley) and H. tenuipes.
This seep is bordered by a social trail, the soil compaction of which provides a little stability. There are also three large Acer macrophyllum (Big leaf maple), two of which are visible below, taken before any restoration work was done.

Central Valley Subarea B in 2011.

Central Valley Subarea B in 2011.

There is a large conifer nurse log (obscured in the photo above) lying across the seep that provides some stability. Tsuga heterophylla (Hemlock) trees have been planted into the nurse log and are doing well.

Hedera helix (English ivy) grows down from the slope, under the trail, and then over the seep. The ivy is not firmly rooted in the seep and provides little or no stability or erosion control. However, clearing the ivy would destabilize the sides of the seep and disrupt the trail.

In November, 2013, some planting was done in Subarea B. They are listed in the table below.

Scientific Name Common Name #
Alnus rubra Red alder 1
Carex deweyana Dewey sedge 6
Carex obnupta Slough sedge 4
Cornus stolonifera Redtwig dogwood 6
Juncus acuminatus Tapertip rush 6
Picea sitchensis Sitka spruce 1
Physocarpus capitatus Pacific ninebark 4
Salix lucida Pacific willow 4
Scirpus microcarpus Panicled bulrush 2

The C. stolonifera were livestakes. All others were potted.

These were installed in two locations in Subarea B. In both cases, only the minimum amount of clearing was done to allow planting. As of summer 2014, all the plants appear to be doing well. We’ve also spread seed berries from Lysichiton americanum (skunk cabbage) into bare areas.

Suggested tasks for Subarea B:

  • Plant shrubs in areas of stable soil, at the base of the slope and around the trees and nurse log.
  • As these establish, spread planting into less stable areas.
  • When the shrub layer establishes, remove ivy from beneath it and increase groundcover diversity.

For further plans for Subarea B, please see “Stewardship Grant,” below.

The ivy comes down to Subarea B from the West and South Slopes. For a discussion of the plans for those HMUs, please see the “Uplands and Slopes” chapter.

Subarea C

Subarea C, outlined in green above, is the least volunteer-accessible area of the Central Valley. It measures approximately 26,490 square feet. The western border is the south loop social trail, and the eastern border is on the floor of the valley. The social trail is frequently 50 and more feet above the floor of the valley, with well over 40% grade. Work here will have to be done by contract or natural area crew, either arranged through Green Seattle Partnership or secured through a grant.

Subarea C is heavily invaded by Rubus armeniacus (Blackberry), Calystegia sepium (Bindweed), and many other ornamental and invasive plants. The true extent of the invasiveness, or what remnants of native plant cover under the blackberry or bindweed, is not known at this time.

Subarea D

Subarea D, at approximately 38,970 square feet (yellow outline above), is the largest area of the Central Valley. The belt transect cut across it at the widest point, but the rest of Subarea D has not been fully explored.

As discussed in “Vegetation,” above, the dense salmonberry and red alder canopy might be controlling the ivy and other invasives – at the cost of preventing tree succession or shrub and groundcover diversity. Care must be taken not to disrupt the salmonberry layer, as this would allow the ivy to take off, and perhaps choke out restoration plantings.

We plan to remove the ivy from underneath the salmonberry in test sections beginning in early spring 2015, before the salmonberry and red alder are fully leafed out. This will allow the sun to reach the soil and promote any seedbank or native growth resurgence. In the summer, we’ll spread seeds from piggyback and other plants already growing in Subarea D. Live stakes from other shrubs growing in the park will be introduced as well, drawing from a number of different plants to avoid problems caused by dense cloning. Deep-shade groundcover will be planted or spread by seed.

As diversity increases, we will remove more ivy and thin the salmonberry to start tree succession. We’ll begin with Alnus rubra. Although this is already the dominant tree cover, it is mainly large, old trees, with no seedlings or sub-canopy examples yet seen. As the next generation of A. rubra establishes, we will begin planting Thuja plicata (Western red-cedar) and Tsuga heterophylla (Western hemlock).

This is a modification of the Bradley method (Bradley, 1988). Although it might sound like it would take longer than the general clearing and replanting, it will have less disruptive impact on existing habitat and aquatic systems (Apastol & Berg, 2006)

Suggested tasks for Subarea D:

  • Remove ivy from under Rubus spectabilis before leaf out
  • Monitor for native plant return from seedbank
  • After seed set, spread seeds from plants already growing under the salmonberry (mostly Tolmeia menziesii [piggyback]).
  • Live stake with stakes taken from other shrubs in the park, particularly Sambucus racemosa (Red elderberry) and Rubus parviflorus (Thimbleberry).
  • In the fall, spread seeds of plants that like deep shade under the salmonberry.
  • When an alder falls, take advantage of the extra light to encourage conifer succession.

All tasks are to be done with as little disturbance to the salmonberry cover as possible.

October Work Party Report

The October work party for Friends of North Beach Park was, once again, a tremendous success. The weather cooperated: it was raining in the morning, but during the work party itself, there were even occasional sunbreaks. It didn’t start raining again until we were safely back home.

We were joined this time by about eleven volunteers from the North Seattle College iCARE program. The students worked hard and well and with the guidance of the forest stewards, we got 450 plants into the ground, which were:

The list

Those are all wetland obligate (they have to live in a wetland) or facultative wetland plants (they prefer wetland environments, but about a third of the time they can be found in drier spots). The Carex amplifolia and Glyceria elata have been seen growing in isolated patches in North Beach Park, but the C. stipata has not been seen in the park at all. The other three have been planted during restoration in small quantities. None of the plants have been seen growing or have been planted near where they were planted Saturday, which will make monitoring of the project in the spring and summer easy.

Julie sorted them into five buckets, 10 or 20 per bucket.

Sorting

The five buckets were to correspond with five areas for receiving the plants. All the plants got put in where they were intended, and we had some extras to spread around.

Working in a seep

Above, we see Loren (bareheaded, in black jacket to the left) and Drexie (kneeling in purple jacket to the right) leading a group of the North Seattle students in planting. They’re working in a seep that wasn’t in the original planting plan, but I was really glad to see get something put into it.

Duckboards

The photo above shows Doug leading other students in planting. They’re standing on “duckboards,” a technical term for sheets of plywood (in this case, just particle board) that you can pick up and move around to avoid churning up the soil of a wetland and breaking the structure. The leaf-fall makes it a little less obvious, but the area they’re about to work in is bare soil, the result of a new shift in the water flow.

Everything went smoothly enough that we were actually done early. Here’s the group picture:

The victorioous crew!

Doug had gone back into the park to plant one straggler. In the back we see Morry on the left, with Drexie, Loren, and Tad in the back center. Julie is kneeling in the front. Everyone else is from North Seattle.

These plants were purchased as partial fulfillment of a stewardship grant from the Central Puget Sound chapter of the Washington Native Plant Society. As I said above, these are all plants that are under-represented in North Beach Park or have not yet been observed growing there. Planting them in such great quantities will greatly increase the ecological diversity of North Beach Park at the herbaceous level, and will help stabilize the seeps against erosion.

As usual, there are a few more pictures on Flickr. And there are even some pictures on Facebook, posted by the iCare coordinator.

Wetlands: Introduction and Headwaters Bowl

This post gives an overview of the wetlands in North Beach Park and looks specifically at the Headwaters Bowl. The next post looks at the Central Valley. The third post in this series will discuss the stewardship grant from the Washington Native Plant Society to the Friends of North Beach Park. The 92nd St. Wetlands will be discussed later, with Fletcher’s Slope.

Approximately 4.5 acres of North Beach Park are designated as wetlands. These wetlands are formed by broad, horizontal, groundwater seeps emerging from the sides of the ravine. These join to form the stream that leaves the park. The seeps are perennial, and have lasted through record droughts.

The wetlands have many areas that are permanently saturated, and walking in them quickly disrupts whatever soil structure there is. Other places are more stable.

Figure 1: Wetlands in North Beach Park. Thick green lines indicate park boundaries. Light grey lines indicate HMU boundaries. The filled blue area are the wetlands. Wetland delineation by Doug Gresham of Gresham Environmental (2012). (Map by the author.)

Figure 1: Wetlands in North Beach Park. Thick green lines indicate park boundaries. Light grey lines indicate HMU boundaries. The filled blue area is the wetlands. Wetland delineation by Doug Gresham of Gresham Environmental (2012). (Map by the author.)

Doug Gresham, of Gresham Environmental, delineated and typed the wetlands in 2012:

North Beach has both Palustrine (freshwater) and Riverine (riparian) wetlands. The plant community is scrub/shrub and the water regime ranges from saturated soil to permanently flowing streams. The groundwater seep wetlands would be called palustrine, scrub/shrub, saturated (PSSc). The stream would be called riverine, upper perennial, unconsolidated shore, permanently flooded (R3USh).

The hydrogeomorphic classification system groups wetlands based on functions and values. … The groundwater seep wetlands would be called slope wetlands and the stream is a riverine wetland.

The Washington Department of Ecology classifies wetlands into four categories based on their hydrogeomorphic class and score from a rating form. King County and City of Seattle governments rely on this classification system to create their critical area ordinances. The highest quality wetlands (Category I) are rare, while low quality wetlands (Category IV) are somewhat rare also. Most wetlands fall into the Category II and III level depending on how well they function. North Beach would probably be Category III because it is degraded. (Gresham, 2014)

In October 2005, the US Fish and Wildlife Service did a fish habitat survey of streams in the Seattle area. “Unnamed PS08 West Fork” is the stream that flows through North Beach Park (see figure 2, below). At their sample site (which would now be in the Headwaters Bowl HMU), they found the stream to have a mean wetted width of 1 meter (m); a mean depth of 0.03m with a max depth of 0.1m; and to consist of 100% riffles with no pools or glides. The substrate was 100% silt/sand. They did not catch any fish in the sample site. (Tabor 2010)

Figure 2: Location of US Fish and Wildlife 2005 survey sample in North Beach Park.

Figure 2: Location of US Fish and Wildlife 2005 survey sample in North Beach Park.

The Central Valley, at 1.97 acres, and the Headwaters Bowl, at 1.39 acres, are the two largest HMUs in North Beach Park. For restoration purposes, we have split them into four subareas each. The subdivision is based on who can do the work: all volunteers, experienced forest stewards, Parks Department Natural Area Crew, or privately-contracted restoration crew.

Headwaters’ Bowl

Description

Figure 3: Headwaters Bowl. The Headwaters Bowl is the area in light green (planting) and blue (establishment). The blue line is the stream. North is to the top.

Figure 3: Headwaters Bowl. The Headwaters Bowl is the area in light green (planting) and blue (establishment). The blue line is the stream. North is to the top. (Source: GSP Reference Map on ArcGIS.com.)

The Headwaters Bowl (“HWB”) is the easternmost HMU of North Beach Park.

The northern boundary is the main trail of the park, the eastern boundary is 24th Ave. NW, the southern boundary is property lines and the South Slope, and the western boundary is the stream crossing and the social trail between the Headwaters Bowl and the Central Valley.

The property lines cut the bottom of the bowl and the 24th Ave. slope in half, and remove the southern slope entirely. Parks Department volunteers and Natural Area Crew are not allowed to work on private property. This complicates restoration of the HWB as discussed below in “Invasive Removal and Restoration Plan.”

At the start of restoration, nearly half the trees in the HWB had severe Hedera helix (ivy) infestations which frequently reached into the canopy. There were large pockets of ivy monoculture on the ground.

The percent cover for trees was approximately 70% deciduous, with Alnus rubra in the wetlands and Acer macrophyllum on the dryer slopes and uplands. There was 5-10% conifer cover, exclusively Thuja plicata (Western red-cedar). The remaining 15-20% cover was open gaps, either over areas too wet to sustain trees or where A. rubra had fallen. The percent cover of the regenerative trees (tall enough to be above the shrub layer) was less than 5% for deciduous and less than 1% for coniferous trees.

Ilex aquifolium (English holly) and Prunus laurocerasus (English laurel) formed occasional dense thickets. Most of these have been removed, either by uprooting or cutting and painting with herbicide.

The HWB native plant communities at the start of restoration were very similar to the Alnus rubra/Rubus spectabilis (Red alder/Salmonberry; ALRU/RUSP) and Alnus rubra/Lysichitum americanum (Red alder/skunk cabbage; ALRU/LYAM) communities described by Kunze (1994). The differences were largely that the communities in the park lacked herbaceous diversity compared to the reference communities.

These communities are dominated by an Alnus rubra (red alder) canopy, with either Rubus spectabilis (salmonberry) or Lysichitum americanum (skunk cabbage) as the undercanopy. Kunze describes the ALRU/LYAM community as being wetter than ALRU/RUSP, and that is the case in NBP. (Plant communities are discussed in more detail in “Target Forest Types”).

There is a canopy gap over the most saturated, eastern part of the HWB. This area is dominated by skunk cabbage and horsetail, with some Salix sitchensis (Sitka willow) shrub. The invasive plants here include Rubus armeniacus (blackberry) and Calystegia sepium (bindweed). Numerous A. rubra lean over this part of the HWB from the slopes. As they die and fall, the gap will enlarge. This will also increase the amount of coarse woody debris in the wetland and the number of rootballs on the slope walls.

Progressing to the west, the topography and soils become more complicated. Some areas are more stable, and some are seeps that have reached down to the gleyed soils. As the ravine narrows, Acer macrophyllum (Big leaf maple) on the south slope add their shade.

The majority of the HWB is in phase two, “planting,” of restoration. A section of Subarea C is considered to be in “establishment,” phase 3. For a discussion of the phases, please see “Monitoring Protocols and Success Metrics.”

Water Flow

Groundwater emerges from several places at the base of the 24th Ave. slope. One of these areas has a number of displaced conduits. During heavy rainfall, water emerges from a conduit in the southeastern corner of the hillside.

Through the rest of the Headwaters Bowl, the water emerges as seeps or occasionally channels from the south slope of the ravine. In many places the seeps have carried away most of the soils.

These seeps join the stream, which runs along the northern edge of the headwaters bowl. Water flow in North Beach Park, in general, needs a lot more research and observation.

Vegetation

As discussed above, the plant communities in the HWB are currently a mixture of ALRU/LYAM (to the east) and ALRU/RUSP (to the west).

The reference ecosystem for the Headwaters Bowl is “riparian forest and shrubland.” The target forest type is ALRU/RUSP/CAOB-LYAM (Red alder/salmonberry/slough sedge – skunk cabbage) as described by Chappell (2006).

There has been one circular, 1/10th-acre, monitoring plot established in the Headwaters Bowl. Baseline monitoring was taken in August 2012, with a follow-up in August 2013. See “Green City Monitoring Protocol” in “Monitoring” for a discussion of this protocol. This monitoring plot was established in the middle of the most saturated section of the Headwaters Bowl.
The following table presents the vegetation findings from the 2012 and the 2013 monitoring and the change. Native plants listed as 0 in the “2012 % Cover” column were planted in autumn 2012. Percent cover was determined by consensus of the people doing the monitoring plot, and is reported in broad categories to enable the data to be consistent across the city.

Table 1: Forest Monitoring Plot report, Headwaters Bowl.

Scientific Name Common Name 2012 % Cover 2013 % Cover Change
Athyrium filix-femina Lady fern 1-5% 1-5% None
Cardamine hirsuta Shotweed 0 <1% Increase
Carex obnupta Slough sedge 0 <1% Increase
Convulvus arvensis Field bindweed <1% 6-15% Increase
Crataegus douglasii Black hawthorne 0 <1% Increase
Epilobium ciliatum Willowherb <1% <1% None
Equisetum arvense Horsetail 26-50% 26-50% None
Fraxinus latifolia Oregon ash 0 <1% Increase
Glyceria elata Tall mannagrass <1% <1% None
Hedera helix English Ivy 26-50% 26-50% None
Lonicera ciliosa Orange honeysuckle 1-5% 1-5% None
Lysichiton americanum Skunk cabbage 1-5% 6-15% Increase
Malus fusca Pacific crab apple 0 <1% Increase
Oenanthe sarmentosa Water parsley <1% <1% None
Polystichum munitum Sword fern <1% <1% None
Ranunculus repens Creeping buttercup 6-15% 6-15% None
Rubus armeniacus Himalayan blackberry 26-50% 16-25% Decrease
Rubus spectabilis Salmonberry 26-50% 26-50% None
Rumex crispis Curly dock <1% <1% None
Salix sitchensis Sitka willow 1-5% 1-5% None
Scirpus microcarpus Small-fruited bulrush 0 <1% Increase
Solanum dulcamara Bittersweet nightshade <1% <1% None
Spiraea douglasii Hard hack 0 <1% Increase

Only one invasive plant decreased in cover, Rubus armeniacus (blackberry). This was the plant we most vigorously removed. The native plants that went from 0 to <1% cover had been planted in the fall of 2012. Lysichiton americanum (Skunk cabbage) increased from the seed bank. Calystegia sepium increased noticeably all over the park in 2013.

Although this gives a good representation of the most-saturated areas of the HWB, it does not give a good representation of the HWB as a whole. A couple dozen feet to the west of this monitoring plot, there is a stand of A. rubra that indicates dryer conditions. This allows greater shrub establishment.

Invasive Removal and Restoration Plan

I have divided the Headwaters Bowl into four subareas, based on who can perform the needed restoration work (see below).

Figure 4: Headwaters Bowl and subareas. A: All volunteers can work here. B: Forest stewards and experienced volunteers. C: Parks District Natural Area Crew (slope). D: Privately contracted crew (slope, private property).

Figure 4: Headwaters Bowl and subareas. A: All volunteers can work here. B: Forest stewards and experienced volunteers. C: Parks District Natural Area Crew (slope). D: Privately contracted crew (slope, private property).

Subarea A

Subarea A is between the main trail and the stream bank. It is relatively flat and dry, making it accessible to all volunteers. It measures approximately 16,500 square feet (all areas calculated using the measurement tool on GSP Reference Map on Arcgis.com).

Subarea A has received the most attention of any area in the park, beginning with the very first work party. As a consequence of it receiving such early attention, no good record was kept of its pre-restoration state; the notes below are reconstructed from memory.

There were few areas of Hedera helix (English ivy) monocultures in Subarea A. There were some areas of Ilex aquifolium (English holly) and Prunus laurocerasus (Cherry laurel) dominance. The ivy has been removed by hand. The holly was removed by uprooting. The laurel was removed by cutting and painting.

In late summer and fall of 2013, several EarthCorps work parties concentrated on invasive removal in this section.
Plants have been installed and invasives removed every year, and it is now in an establishment phase.

Suggested tasks for Subarea A:

  • Explore the western end in further detail.
  • Continue monitoring the planted area for native plant establishment and invasive resurgence.
  • Track mature Alnus rubra and naturally regenerating Thuja plicata and Acer macrophyllum.
  • Start a new generation of deciduous trees.
  • Add to the herbaceous diversity annually.
  • In 2021 (ten years after restoration began), add a new generation of conifer trees.

Subarea B

Subarea B is the center of the bowl, and because of the saturation and fragile soil structure is more difficult to work in than Subarea A. This makes it accessible to small groups of experienced forest stewards only. It measures about 45,000 square feet.

The widest part, to the right in the image, is permanently saturated. It receives invasive removal in the late summer, when it’s relatively dry. It has received plantings of graminoids and shrubs. The eastern edge of Subarea B is the location of the circle monitoring plot discussed above. The part of Subarea B not in park property needs further exploration.

The narrower part has many seeps, separated by tongues of soil held in place by Carex obnupta (slough sedge) and/or Rubus spectabilis (salmonberry). In the spring and summer, these seeps contain forbs such as Oenanthe sarmentosa (Water parsley). However, there is no woody vegetation to hold the seeps during winter.

Some Picea sitchensis (Sitka spruce) and Thuja plicata (Western red-cedar) have been planted in the seeps.

In June 2014, Friends of North Beach Park received a $500 stewardship grant from the Puget Sound Chapter for the purchase of wetland plants. These plants will be installed along the streambank and in the seeps of the western (left) edge of Subarea B of the Headwaters Bowl, and across to Subarea B of the Central Valley. This grant is discussed in more detail in “Stewardship Grant.”

Suggested tasks for Subarea B, in the lobed area to the east:

  • Continue removing blackberry.
  • Establish shrubs where possible, graminoids elsewhere.
  • Explore the base of the slope and the bowl during a rain event.

Suggested tasks for Subarea B, in the narrow part to the west:

  • Implement the WNPS Stewardship Grant in autumn of 2014.
  • Continue removing invasives as necessary.
  • Monitor seeps for erosion.
  • Establish obligate wetland plants in the seeps.

Subarea C

Subarea C measures roughly 10,200 square feet. It is the slope along 24th Ave NW and around the entrance to the park along the main trail. Because it is a greater than 40% grade, only Parks Department Natural Area crew or contract crew can work on it. Volunteers have worked on it in the past, however.

In 2011, trees along the rim and slope received survival rings and there was some clearing of the slope.

In 2012 and 2013, the rim received some planting by the Friends of North Beach Park. During the summer months, these plants are watered and weeded. These plants include shrubs such as Aruncus dioicus var. acuminatus (Goatsbeard), Rosa nootkana (Nootka rose) and trees such as Pseudotsuga menziesii (Douglas-fir) and Pinus contorta var. contorta (Shore pine).

In 2013, the slope was partially cleared by a group of EarthCorps volunteers. The clearing was completed by a contract crew, who also put down jute rolls and planted in the fall.

Figure 5: Steep slope jute erosion control by contract crew.

Figure 5: Steep slope jute erosion control by contract crew.

The remainder of the clearing, following the curve of the slope along 24th Ave. and ending at the property line, will happen in 2014 or 2015.

Volunteers and forest stewards can maintain the plants at the rim and the base, but further tasks along the slope in this subarea will be executed by the Parks Department.

Subarea D

Subarea D measures approximately 13,800 square feet. It has not been explored in any great depth. Some trees were given survival rings during the first work parties in 2011. One house appears to have impermeable erosion control fabric, held down by sandbags, on the slope beneath it.

Subarea D is entirely private property on a very steep slope. The houses were built between 1959 and 1963 (King County Parcel Viewer), long before there was any movement to make the ravine a park or any attempt to preserve urban wetlands. The property lines, as shown below, extend into the bowl of the park, which allows the owners to have addresses on 24th Ave. This group of houses, as a whole, is called Olympic Terrace.

Figure 6: Property lines and park boundaries of HWB. The green area is North Beach Park. The red lines are parcel boundaries for private property. (Source: Seattle Department of Public Development DPDGIS).

Figure 6: Property lines and park boundaries of HWB. The green area is North Beach Park. The red lines are parcel boundaries for private property. (Source: Seattle Department of Public Development DPDGIS).

Due to the steepness of the slope, and the fact that it is private property, Subarea D can only be worked on by a privately contracted crew.

Working in Subarea D depends on securing the cooperation of the homeowners. We plan to contact them in autumn 2014 or early 2015 by doorbelling or leaving door hangers. If this contact is successful, we will

  • Explore the area along the bowl and the base of the slope to get an estimate of its invasiveness and what work needs to be done.
  • Design restoration plans that range from one-year brute force through multi-year phased work (which plan gets executed would depend on the size and time span of the grant).
  • Work with neighbors to write a grant that can be applied to private property (with King Conservation District or other organization).
  • Restore Subarea D per grant.

The large contingencies in this plan are (a) successfully contacting and securing the cooperation of the neighbors and (b) obtaining the very competitive King Conservation District grants.

The constraints against working in Subarea D would make it low priority if it were in another section of the park. However, its proximity to the headwaters increases its importance.