Ordinance No. 20513 - Laserfiche WebLink

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essential that the design include the establishment of maintenance paths and other infrastructure to make ongoing management efficient and cost - effective. Plantings on the Upper Banks, Millpond Swale and the Pollinator Prairie will be easier to carry out although it is possible that some soil will need to be added since existing soil may be compacted from past asphalt and vehicular traffic. Native nursery stock could be used as well as locally collected native seeds depending on the cost, availability and overall desired outcome. Nursery stock can be convenient to use in areas where there are few obstacles and level ground. Furthermore, using planted stock provides more rapid establishment and growth so that the desired habitat can be created more quickly. The Pollinator Prairie, however, might be more easily and cost - effectively established if primarily sown with the appropriate local native seeds and supplemented with nursery stock or plugs as needed. Extensive site preparation is critical prior to planting to control existing non - native species as well as their soil seed bank. Current local restoration experience by the City of Eugene, The Nature Conservancy and federal agencies is that at least two years of site preparation creates much higher quality prairies with much lower long -term management cost. Invasive species management is central to maintaining healthy and attractive native plant communities. Invasive exotic species may outcompete or compromise the growth of native trees, shrubs, forbs and grasses, and thus diminish the food, host and nesting potential of these plants for native (and other) birds, insects and mammals. Dense overgrowth of invasive species can prevent tree regeneration in important areas like riparian zones, diminishing the riparian forest's ability to provide shade for water temperature control, and to supply woody debris and litter for aquatic invertebrates, which in turn can compromise the health and survivorship of native fish. The river's edge receives a constant influx of invasive species that needs to be monitored and managed on a yearly basis. Early detection is often the key to efficient and economic control. Dense exotic shrubs such as Himalayan blackberry (Rubus armenaicus) and Scots broom (Cytisus scoparius) are not high quality wildlife habitat and can alter the soil chemistry so that native species are less able to compete. Dense stands of invasive species can also provide hiding places for humans, creating potential safety issues or the perception of unsafe conditions. See Appendix C of the full report for selected invasive species control recommendations and techniques. The importance of clearly defined goals, measurable benchmarks for what is considered to constitute success, and a well - established management plan that allows for adaptively monitoring and managing the site over the long term cannot be overemphasized. Plant species diversity in riparian zones was historically maintained by such disturbances as flooding. In its absence, human management is needed to prevent either invasive exotic species or competitively dominant native species from taking over and reducing diversity below desired levels. Qualified personnel who understand how to maintain native plantings as well as selected ornamental characteristics are essential. The City of Eugene natural resources management team is an excellent source of such knowledge and personnel. 24