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of 2000 indicates a high level of diversity range of native herbaceous species. Much
<br /> and the resence of several s ecies of of the ri arian zone is also dominated b
<br /> P p p y
<br /> native /ants that have become local/ invasive s ewes such as Himala an
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<br /> uncommon. Up/andsavanna prairie is also blackberry, English ivy and reed canary j
<br /> and endangered habitat type, and highly grass. ~~n u~.
<br /> valuable for preservation. u~:
<br /> A Landscape Under Siege ivortn side Forest i
<br /> South Skinner Butte Mixed Forest: Skinner Butte Park is under attack by ~ ~ ~
<br /> Much of this area is in transition from the invasive plants, Most of us don't recognize ~ ' k'
<br /> original upland prairie habitat towards a them for what they are. But they're here,
<br /> mixed hardwood and conifer forest. Some and new invasive species are arriving every
<br /> of this transition is occurring through the day. Every native landscape in the world
<br /> natural succession of native trees and is undergoing the same kinds of dramatic i
<br /> shrubs, although a larger percentage is as change, but in an urban area with a mild
<br /> a result ofhuman activityin conjunction with climate, good soils and plenty of water, the Remnant Oak Savanna Transition `
<br /> beautification projects, as well as the rapid effects are dramatic.
<br /> advance of invasive species. Forest types
<br /> include dense groves of incense cedar, The changes are easy to see when you
<br /> stands of bigleaf and Norway maple, know what to look for. The forest on the
<br /> Mazard cherry, Douglas fir, madrone, giant north side of Skinner Butte is covered with
<br /> sequoia, pine and others. Other areas are a carpet of dark green, glossy English ivy. b`~' ~
<br /> dominated by thickets of predominantly This ivy has spread enormously in recent '
<br /> invasive species such as English hawthorn, decades, and has threatened to literally Upland Prairie ~
<br /> Scotch broom and Himalayan blackberry. choke the life out of the forest and other
<br /> Most/ because these forested areas are
<br /> y native habitats. Ivy covers the ground and z: `
<br /> young, they do not support the diversity of robs native plants of light, and competes .
<br /> native plants characteristic of older, native for nutrients and water, Most native plants
<br /> forest. Aseedbedofdormantnativeup/and are suppressed under the green carpet.
<br /> prairie species lies beneath the manyareas What was once a diverse forest floor of
<br /> of the transitional forest and dense cover of annuals, perennials, ferns and wildflowers
<br /> invasive species. Previous restoration work is smothered, along with the creatures that
<br /> has shownthatsomeup/andprairiespecies depend on them. The ivy also grows South Skinner Butte Mixed Forest '
<br /> return quicklywhen the covering vegetation quickly high into the branches of trees,
<br /> A
<br /> is removed. reaching towards the light and eventually • ~ ~ ~ ~ '
<br /> shading out and killing the host tree. ~r ~
<br /> Willamette River:
<br /> A significant stretch of riverbank habitat For several years, efforts have been
<br /> extends along the northern boundary of the underway to control the ivy. Crews have ~
<br /> park. This zone varies in width from several concentrated on removing it from the trees,
<br /> feet to several hundred feet, and includes cutting the stems where they sprout up from Willamette River
<br /> good examples of a diversity of structural theforestfloor. Other groups of volunteers,
<br /> features and habitats common to the botanists and ecologists are experimenting '
<br /> Willamette River, such as fluvial terraces, a with removing ivy from the ground. New
<br /> seasonal island, gravel bars and a small evidence shows that, once the carpet of ' '
<br /> backwater slough. Vegetation in this area ivy is taken away, the native plants are quick `
<br /> is dominated by willow, dogwood anda/der to return. This is good news for forest
<br /> along the more stable river bank edges, habitats in many city parks, including
<br /> large cottonwood throughout the terrace Hendricks Park, where aggressive, j
<br /> areas, and mature bigleaf maple, Douglas organized efforts are underway to control
<br /> firand Oregon white oak on the steep bank ivy in the park by the year 2010.
<br /> between the upper and lower terrace, and
<br /> along the edge of the upper terrace. Several Other invasive plants are contributing to the
<br /> significant tree specimens are foundin this decline of Skinner Butte Park's native
<br /> area. Understory vegetation includes ecosystems. Plants like Himalayan
<br /> snowberry, osoberry, and ninebark and a blackberry, Portugal laurel, English laurel, ` . .
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<br /> 38 Chapter 3: Inventory and Assessment -
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