Figure 1: The West Slope.
The West Slope is bordered by property lines above and the south loop social trail below. The northeastern and southeastern corners touch Fletcher’s Slope and the South Slope, respectively. It is 0.84 acres in size.
The northeastern corner of the West Slope has a large gap that provides an expansive view of the Central Valley. The southwestern corner of the West Slope is the west end of the 90th St. right of way. Two plots of the June belt transect were established there (see “Vegetation” below).
Other than several Pseudotsuga menziesii (Douglas fir) that were planted below the 90th St. end, the West Slope has received no restoration efforts. The Natural Area Crew will work on this area after the South Slope.
The West Slope has the largest Tsuga heterophylla (Western hemlock) in North Beach Park, but no other coniferous cover. There is no observed regeneration of either deciduous or conifer trees. Between the large gaps, and the extent of Prunus laurocerasus (Cherry laurel) cover in the middle, the West Slope has the least amount of native tree cover of any HMU.
The target forest type for the West 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.
There has been no observed water flow on the West Slope. It is too far above the floor of the Central Valley to be affected by any seeps emerging from the walls of the ravine.
The West Slope is currently among the most heavily invaded HMUs in North Beach Park. There is an extensive canopy of Prunus laurocerasus (laurel); Lamium galeobdolon (Yellow archangel) is spreading down from a house; and, at 90th St., there are a number of sun-tolerant grasses and ornamentals. Bindweed is rampant in the sunnier parts of the West Slope.
Two 4×4’ plots of the belt transect were established in the West Slope. These plots were smaller than the other plots in the transect due to the density of herbaceous cover in this area.
Table 1, below, shows the target forest type indicator species for the North Slope and all species found in our survey. Please see the Key, below the table, for a full explanation of the numbers.
Table 1: Target Forest Type and transect species for the West Slope.
|Binomial||Common Name||% Cover||TFT Goal|
|Abies grandis||Grand fir||0.00||14.00|
|Acer circinatum||Vine maple||0.00||20.00|
|Acer macrophyllum||Big leaf maple||20.00||18.00|
|Agrostis stolonifera||Creeping bent grass||2.50||0.00|
|Alnus rubra||Red alder||0.00||9.00|
|Athyrium filix-femina ssp. cyclsosorum||Lady-fern||0.00||2.00|
|Bromus vulgaris||Columbia brome||0.00||2.00|
|Calystegia sepium||false bindweed||0.50||0.00|
|Carex deweyana var. deweyana||Dewey’s sedge||0.00||2.00|
|Corylus cornuta var. californica||Beaked hazelnut||0.00||3.00|
|Dactylis glomerata||Orchard grass||1.75||0.00|
|Dryopteris expansa||Spreading wood fern||0.00||3.00|
|Equisetum telmateia||Giant horsetail||1.00|
|Galium triflorum||Sweet-scented bedstraw||0.00||2.00|
|Geranium robertianum||Robert’s geranium||1.50||0.00|
|Hedera helix||English Ivy||3.50||0.00|
|Holcus lanatus||velvet grass||4.00||0.00|
|Hypochaeris radicata||Hairy cat’s ear||0.25||0.00|
|Berberis nervosa||Dward Oregon-grape||0.00||4.00|
|Mycelis muralis||Wall lettuce||0.25||0.00|
|Plantago lanceolata||Narrow-leaf plantain||0.25||0.00|
|Polystichum munitum||sword fern||20.00||54.00|
|Pseudotsuga mensiesii var. menziesii||Douglas-fir||0.00||45.00|
|Pteridium aquilinum var. pubescens||Bracken fern||0.00||3.00|
|Ranunculus repens||Creeping buttercup||3.00||0.00|
|Rubus armeniacus||Himalayan blackberry||5.00||0.00|
|Rubus ursinus||Trailing blackberry||0.00||3.00|
|Rumex obtusifolius||Bitter dock||0.25||0.00|
|Sonchus oleraceus||Common sowthistle||0.25||0.00|
|Tanacetum vulgare||Common Tansy||35.00||0.00|
|Taraxacum officinale ssp. officinale||Common Dandelion||0.75||0.00|
|Thuja plicata||Western red-cedar||0.00||33.00|
|Tiarella trifoliata va. Trifoliata||Threeleaf foamflower||0.00||5.00|
|Trientalis broealis ssp. latifolia||Western starflower||0.00||1.00|
|Trifolium repens||White clover||0.25||0.00|
|Trillium ovatum ssp. ovatum||Western trillium||0.00||1.00|
|Tsuga heterophylla||Western hemlock||0.00||36.00|
|Urtica dioica||Stinging nettle||0.25||0.00|
|Vaccinuium parvifolium||Red huckleberry||0.00||3.00|
|Vancouveria hexandra||Inside-out flower||0.00||7.00|
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.
Of the 26 TFT indicator species, only two were found in this survey. Only five of the 22 species found in the survey were native. No native species was found in more than one plot, and four of them were in the plot further from the street end.
The restoration plantings of Pseudotsuga menziesii (Douglas fir) were close to, but not in, the first plot. They are planted more densely than recommended and a little too high on the slope. The dense planting is to allow for infant mortality. The intention is that they will shade out the sun-requiring invasive species.
Heavy pulling of the weeds on this steep, dry slope would disturb the soil too much and possibly lead to a slope collapse. After the Douglas fir establishes, we will look into cardboard sheet mulching. We have also discussed with the homeowner adjacent to the street end the possibility of a native hedgerow, both to shade the slope and to prevent illicit access to the park.
Having said all that, this is an atypical section of the West Slope. But given the variety of aspects to the slope and the number of escaped ornamentals, there is no “typical” section of this HMU.
Invasive Removal and Restoration Plan
No part of the West Slope is accessible to volunteers. Some parts, bordering the social trail, are accessible to forest stewards.
In general, the West Slope is very low priority. The large, spreading cover of Lamium galeobdolon (Yellow archangel) has been reported to Green Seattle Partnership.
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