Alien Invaders!!
Impacts of Invasive Plant Species in Oregon
Erin Tirone
Road Map
• Definitions
• Examples of Invasive Species
– Description
– Impacts on native landscape
• Eradication Methods
– Pros/cons
• Questions
What does it mean to be…?
• Native
– A plant or animal originating from a particular
place or region
• Endemic
– Native to or confined to a certain region
• Invasive
– Marked by a tendency to spread
– Tendency to intrude or encroach
Why do plants become invasive?
• “New” environment similar to native
environment
• Better competitors than the natives
• Efficient adaptations
• No natural predators in “new” environment
• Opportunistic
Himalayan Blackberry
• Native to Eurasia,
pervasive in Oregon
• Spreads rapidly
through underground
growth and seed
dispersal
• Establishes itself in
sunny disturbed areas
English Ivy
• Europe native
• Spreads by extension
of runners
• Many negative
impacts on plant and
habitat diversity
• Attempts at mitigation
in Forest Park
Reed Canarygrass
• Native for Europe and
Asia (though still
being debated whether
it is actually native to
North America)
• Spreads through
rhizomes and seed
dispersal
Scotch Broom
• Scotland native
• Grows on open,
sunny, disturbed sites
• Produced enormous
amount of seeds,
which are viable for
up to 80 years
Japanese Knotweed
• Introduced from Asia,
perhaps as ornamental
plant
• Grows through
rhizomes
• Establishes itself in
moist ravines, ditches,
and disturbed areas
Morning Glory
• Eurasian native
• Grow in disturbed
areas, commonly
found along
waterways, fields and
roadsides
• Grow from rhizomes,
are ground creepers
Clematis
• Common in disturbed
open canopy areas
• Spread through wind
dispersal of seeds
from wispy flowers
Common Methods of Eradication
• Pulling out the roots
• Cutting canes (blackberry)
• Soil solarization
• Planting Native plants
• Herbicide application
– Spraying
– Spot application
Works Cited
• Invasive and Exotic Species of North America. 2002.
USDA Forest Service. http://www.invasive.org
• Invasive Plants--A Guide for Dealing with Non-native
Species. Beaverton, OR: Natural Resources Office,
Tualatin Hills Park and Recreation District
• Pojar, J. & A. MacKinnon. 1994. Plants of the Pacific
Northwest Coast. Vancouver, B.C.: Lone Pine.
• Reed Canyon Enhancement Strategy. Non-native Species
Management. 2001. Portland, OR: Reed College.
http://web.reed.edu
• Taylor, R.J. 1990. Northwest Weeds. Missoula, MT:
Mountain Press.