holyoutlaw: (me meh)

Description

The 91st St. Slope is a long, narrow strip that runs between the main social trail at the lower end and property lines at the upper. It is 23,313 square feet. Because of its steepness, it’s relatively unexplored.

The southeast corner is known as “Knotweed Hill” because it had a thicket of Reynoutria japonica (Japanese knotweed) that was treated in 2012. There is some knotweed resurgence that has been reported and is being monitored. For the full story of Knotweed Hill, please see “Park and Restoration History.”

The majority of the 91st St. Slope has no conifer canopy and less than 1% conifer regeneration. However, at the north end, where the 91st St. Slope abuts the 92nd St. wetlands, there is close to 10% Tsuga heterophylla (Western hemlock).

The target forest type for the 91st St. Slope is Tsuga heterophylla – Pseudotsuga menziesii/Polystichum munitum – Dryopteris 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

One section of the trail bordering the 91st St. Slope dips below the water table. No other water flow has been observed from the 91st St. Slope.

Vegetation

Trailside, there are canopy gaps along this HMU that encourage the growth of blackberry and even grasses. There are dense laurel thickets, which were treated in the summer of 2014 with stem injection. Most of the rest of the trailside vegetation is Rubus armeniacus (blackberry) with Hedera helix (ivy) and some Rubus ursinus (trailing blackberry).

In October, 2012, three Alnus rubra (Red alder) trees fell from the 91st St. Slope across the main social trail and into a laurel thicket. This enlarged a canopy gap and blocked the trail until February, 2013, when it was cleared by the Natural Area Crew.

Because of the steepness of the rise from the trail, it’s difficult to see what is on the slope. The 91st St. Slope still has some trees that need ivy survival rings, but they are on nearly vertical sections of the slope.

No systematic monitoring has been done for the 91st St. Slope. However, what we have observed growing is listed in Table 1, below. Please see the key below the table for an explanation.

Table 1: Plants observed growing on the 91st St. Slope.

Scientific Name Common Name Inv TFT 91st Slope
Abies grandis Grand Fir   1 R
Acer circinatum Vine maple   1  
Acer macrophyllum Big Leaf Maple   1 G
Alnus rubra Red Alder   1 G
Asarum caudatum Wild ginger     R
Athyrium filix-femina Lady Fern   1  
Blechnum spicant Deer Fern   1  
Bromus vulgaris Columbia brome   1  
Carex deweyana Dewey’s sedge   1  
Claytonia sibirica var. sibirica Siberian spring beauty     G
Corylus cornuta Beaked Hazelnut   1  
Daphne laureola Spurge Laurel 1   G
Dryopteris expansa Spiny Wood Fern   1  
Galium aparine Bedstraw     G
Galium triflorum Sweet-scented bedstraw   1  
Gaultheria shallon Salal   1  
Hedera helix English Ivy 1   G
Hydrophyllum tenuipes Pacific Waterleaf     G
Ilex aquifolium English Holly 1   G
Impatiens glandulifera Policeman’s helmet 1   G
Lonicera involucrata Twinberry     R
Mahonia nervosa Dull Oregon-grape   1 G
Malus fusca Pacific Crab Apple     R
Oemleria cerasiformis Osoberry (Indian plum)     G
Osmorhiza berteroi Sweet Cicely     G
Polystichum munitum Sword Fern   1 G
Pseudotsuga menziesii Douglas-fir   1  
Pteridium aquilinum Bracken Fern   1  
Ranunculus repens Creeping buttercup 1   G
Reynoutria japonica Japanese Knotweed 1   G
Rosa gymnocarpa Baldhip rose     R
Rosa nutkana Nootka rose     R
Rubus armeniacus Himalayan Blackberry 1   G
Rubus spectabilis Salmonberry   1 G
Rubus ursinus Trailing blackberry   1 G
Rumex occidentalis Western dock     G
Sambucus racemosa ssp. pubens Red Elderberry   1 G
Taxus brevifolia Pacific Yew     G
Thuja plicata Western red-cedar   1 G
Tiarella trifoliata Threeleaf foamflower   1  
Tolmiea menziesii Piggyback Plant     G
Trientalis borealis ssp latifolia Western starflower   1  
Trillium ovatum Western Trillium   1  
Tsuga heterophylla Western Hemlock   1  
Urtica dioica Stinging Nettle     G
Vaccinium parvifolium Red Huckleberry   1  
Vancouveria hexandra Inside-out Flower   1

Key: Bold plant names indicate plants listed in a target forest type but not observed growing in any HMU. “1” in Inv column indicates the plant is considered invasive. “1” in TFT column indicates the plant is listed in the Target Forest Type description for the 91st St. Slope. “G” or “R” in the 91st St. Slope column indicates the plant has been observed growing or has been planted as part of restoration activities.

Of the 30 plant species observed growing in the 91st St. Slope HMU, seven (23%) are invasive. Of the 26 plants listed in the target forest type for the 91st St. Slope, nine (34.6%) are found growing in the HMU. These numbers would probably change with systematic observation.

Invasive Removal and Restoration Plan

Figure 1: 91st St. Slope

A: Accessible to volunteers. B: Contract Crew.

A: Accessible to volunteers. B: Contract Crew.

Subarea A

Subarea A measures 9,400 square feet and is accessible to all volunteers. It is separated from a similar volunteer-accessible area in the Central Valley HMU by a narrow social trail.

EarthCorps, in the fall of 2013, did some invasive removal in the Central Valley adjacent to the 91st St. Slope, reaching to about the dogleg in Figure 1, above.

In the winter of 2014, Friends of North Beach Park leap-frogged this restored area and cleared about 800 square feet on both sides of the trail of blackberry brambles.

Our intention was to continue clearing back towards the EarthCorps-cleared area over the summer months. However, in May and June we instead worked on aftercare for plants installed in dryer areas of the park, particularly near the entrance. In August, we did some re-clearing because the area had had a resurgence of invasives, particularly Ranunculus repens (creeping buttercup).

In August, a contract crew from the Parks Department injected a laurel stand with herbicide.

In November, Friends of North Beach Park cleared and planted in the area. Most of the plants were installed on the Central Valley side of the trail.

Suggested tasks for Subarea A:

  • Survey the area to be cleared between where the Friends of North Beach Park worked in January 2014 and EarthCorps worked in Fall of 2013.
  • Plan a series of public and forest steward workparties to bring the two areas together.
  • Work closer to the trail during wet weather, move to the streambank in the summer.
  • Use burlap and mulch to cover bare areas.
  • Use GSP provided plants to fill in in the fall.

The tasks above were written in the summer of 2014. As of the fall of 2014, work on the 91st St. Slope has been demoted in favor of concentrating on the Headwaters Bowl.

Subarea B

Subarea B is unexplored as of fall 2014. It is lower priority than the South or West Slopes, which have a much higher extent of invasion; consequently, there is no crew time scheduled or predicted for this subarea.

Suggested tasks for Subarea B:

  • Explore as much as possible.
  • Put survival rings on any trees that need them.

References

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.

Mirrored from Nature Intrudes. Please comment over there.

holyoutlaw: (me meh)

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.

Mirrored from Nature Intrudes. Please comment over there.

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