Ordinance No. 20513 - Laserfiche WebLink

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Plant Community Design Palette Appendix A provides detailed information on each of the plant species listed below for the different plant communities. This includes the areas where each species could be used, its requirements for light and moisture, the ecological functions it provides, its landscaping qualities, and finally its average height, canopy spread and growth rate. Species for the Riparian Floodplain and Upperbank/Midbank communities include shade - loving forest plants as well as sun - loving species. In part this is because the mature plant communities in each zone may intentionally range from forest to forest gaps to more open habitats. In addition, even in areas designated for forest, it will take many years for planted trees to reach large enough size that they will shade the ground sufficiently to support forest understory species. The urban habitat type is not specifically described below, but would be comprised in large part of native species selected from the following lists, as well as selected non - invasive introduced species that require minimal supplemental water, fertilization or pest or disease control. Riparian Floodplain Zone: This is the area located closest to the river's edge where the plants generally have direct access to the groundwater and the hyporheic zone, where there is active and important exchange between belowground flows of water moving roughly in tandem with active channel flows. The elevation for this habitat zone varies between 400' and 408' and encompasses approximately 1.0 acres. This area currently has a moderate to high density of riparian trees at least one row wide along much of the river's edge. Due to the narrowness of the current floodplain benches and steepness of these north and east facing banks, there is not sufficient canopy space remaining between the river's edge and the current bike path for the addition of many more large trees (see Appendix A for average canopy widths of the proposed species). We therefore recommend a focus on planting large trees in areas where none exist and potentially infilling some of the currently treed areas with smaller trees, shrubs and herbaceous species. The addition of more large- canopied trees in areas where the banks will be laid back and also in the Upperbank/Midbank areas closest to the Riparian Zone will greatly increase the effective width and shading capacity of this zone. The species listed directly below are tolerant of wet soils as well as high water flows. They can also serve to slow the speed of higher flows, provide erosion protection and bank stabilization as well as provide shade to help maintain lower river water temperatures. Tree species could include: Alnus rhombfolia Alnus rubra Fraxinus latifolia Populus trichocarpa Forb species could include: Scutellaria later flora Stachys cooleyae Urtica dioica Shrub and small tree species could include: Cornus sericea Crataegus suksdorfi Malus fusca Physocarpus capitatus Salix hookeriana Salix lucida ssp. lasiandra Salix sitchensis Symphoricarpos albus var. laevigatus Viburnum ellipticum Grass, rush and sedge species could include: Carex obnupta Carex hendersonii Carex interupta Juncus effusus ssp. pacificus (do not confuse with invasive J. effusus ssp. effusus) Juncus occidentalis IM