Invasive Species 101:Primer for Green Industry Professionals
Robert Emanuel, Ph.D.Water Resources and Community Development Faculty,
Tillamook and Clatsop counties
Introduction
What are invasive species?
Why should we care?
Biology & management
Some invaders to watch
What can professionals do?
Resources for more information.
Invasive species means an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.
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Invasive species are a serious issue—but what are they? Here’s the federal government definition of IS. Here are some examples of the types of harm they create: Hypoxia killed this fish because the water weed—Hydrilla verticulata, produced extra biomass-that biomass was consumed by bacteria and other organisms in the water column, all the while those organisms consumed the free oxygen that kept the fish alive. These tiny NZ mudsnails reproduce so quickly that they can cover most of the benthic (bottom) habitat in a stream, hence outcompeting any of the normal invertebrates that fish consume—and the snails are largely useless to the fish themselves. They can move around by fishing tackle, boots, boats, trailers, bait buckets, etc. Yellow star thistle here is consuming intermountain west rangelands faster than any other single weed (next to cheat grass). The plants provide no nutrition and in fact, are toxic to some livestock. 160,000 acres have been consumed in E. Oregon, while CA is dealing with over 10 million acres of infestation! The nutria pictured here is eating the wetlands of Louisiana out of existence, contributing to the loss of a football field a day of wetlands in that state. When hurricanes come, they cause more damage because they cross more open water before hitting cities like NOLA with greater force. These zebra mussels and their cousins quagas should scare the daylights out of Oregon’s electricity rate payers because if they get to the hydropower dams on the Columbia, they will cost us 25 million a year in control costs alone. Moreover, the move with every boat that goes into the river and will lead to fouling of everything below the surface. They could lead to complete collapse of the salmon fisheries on the PNW if they become widespread. They have already infested some waters in California , Arizona, and Nevada, leading many to fear they will make it here soon.
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Invaders get here by many means including: 1. Ballast and packaging in container ships 2. In baggage of travelers 3. Via crops and seed in agriculture 4. Through the pet trade
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Gardeners are responsible too—as many as 50-80% of all invaders are horticultural in origin.
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Nurseries and professional growers too can help spread invaders. The longer an exotic is in “the trade” the more likely it will become invasive somewhere.
Biological invaders destroy habitats or out‐compete native plants and
animals.
At least 30 new potential biological invaders enter the US every day…
Invasive species costs Americans about $143 billion/year!
Why should we care?
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We are at the early stages of recognizing this issue—much like the early 1970s when these successful ad campaigns got the public thinking about pollution and litter as problems. We don’t yet have a similar campaign to capture the hearts and heads of the public. Part of the problem is that plants and other organisms are not something people think about during day-to-day activities. Instead, most see only recognize the existence of a tree, a grass, or a bug. Our job is to help educate people and spread this awareness deeper into the public.
Understanding Biological Invasions
“Invasive”
Definitions: Invasive Plants
Exotics(non‐native)Lots of beneficial species: Crops, pasture, forestry & ornamentals.
“Noxious”A regulatory designation.
“Weed”A plant growing where you do not want it.
Spreads outside of cultivation, and causes environmental& economic harm.
NativesCo‐evolution with other species, our natural heritage
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Weedy terms are used interchangeably, resulting in this problem. Euler diagrams Not all non-native plants are considered harmful or invasive. Of the 4,000 species of exotic plants that have become established as free-living populations in the United States, roughly 10 percent have been identified as a threat to our native flora and fauna as a result of their invasive characteristics (Kastalerz, NCBG). Many non-invasive alien plants are important to the agricultural economy including apples, corn, soybeans, sweet potatoes, and tomatoes. Volunteers may reseed from these important crops but they do not "crowd out and smother" populations of native plants. In addition, North American native plants can be considered invasive. For example, black locust, Robinia pseudoacacia, is native to the southeast but was planted for fence posts across the U.S. Outside it's native range, black locust is considered an exotic and in some places it is considered invasive because of its rapid growth and reproduction.
What makes a plant invasive?
Lack normal environmental constraints
Fast growth and reproduction
Highly adaptable a wide range of conditions
Often can transform their environment
Promoted by new or existing disturbances
Less biodiversity in the native ecosystem
Sometimes work with other invasive species
Key Stages in Plant InvasionsArea Infested
Time
Lag Time
Escape
IntroductionInvasion
Cost
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The biological invasive process is fairly straight forward. Unfortunately, we often forget that the process is best stopped at the introduction and escape phases, while most of us notice the invasion when it’s “out of the box” on the upper part of the curve. At that point, things cost much more and harm is already multiplied.
What does this mean for management?Area Infested
Prevention or Eradication(Inexpensive)
Local control and management only
(Expensive)
Control Costs
Time
Introduction
Detection: focus resources here
People notice them here
The Wildfire Model
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Wildfires are good models for invasions. They travel by means of conditions (good fuel, heat, oxygen), can be stopped small and only contained when they get big. They also jump around the same way as a fire moves by sparks and embers. Fires can start and “sleep” for periods of time then awaken and become conflagrations quickly.
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An ironic example is bromus tectorum, or cheat grass, which uses animal and human vectors to move very quickly and—the irony is that it is a fire-prone species itself—therefore adding or enhancing fire where it establishes itself in large infestations.
How do we manage invasive plants?
Prevention
Quarantine before introduction
Monitoring & mapping
Chemical treatment (herbicides)
Biological controls (biocontrol)
Cultural treatment (hand pulling, cutting, etc.)
*
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The noted bullets are places where professionals and gardeners both have an influence.
Some Invasive Species
High Desert Oregon & Environs
Flowering Rush: Butomus umbellatus
Photo – butterfly bush infestation in Lane Co.
Butterfly Bush: Buddleja davidii
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Butterfly bush flowers provide nectar for adult butterflies, as do many other flowers as well. The food necessary for a butterfly’s larvae, however, is usually only one species or a few related plant species. Some native butterfly species depend on willows for their larval food, one of the plants crowded out of its streamside habitat by butterfly bush. Photo: Brad Withrow-Robinson
Photo ‐ butterfly bush infestation in Lane Co.
Butterfly Bush (Buddleia davidii) Photo: OSU
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This butterfly bush infestation is along the Salmon River in Lane County. Butterfly bush produces abundant seeds that are easily spread by water, and it thrives on sites with regular disturbance. It grows well in infertile soils; it tolerates summer drought and winter flooding. Photo: Brad Withrow-Robinson
3) Bohemian knotweed is a hybrid of Japanese knotweed (Polygonum cuspidatum) and giant knotweed (Polygonum sachalinense). Photo: Sasha Shaw
Japanese knotweed (Fallopia cuspidatum) & giant knotweed (Fallopia sachalinense)
Yellow Flag Iris: Iris pseudacorusPhoto: OSU
Yellow flag iris (Iris psuedacoris)
Photo: Paul Wray, Iow
a State University
Russian Olive: Elaeagnus angustifolia
Tree of Heaven: Ailanthus altissima Photo: USFS
Jan Samanek, State Phytosanitary Administration, Czenia
Tamarix ramosissima
Tamarix parviflora Leslie Gulch, OR, 2007
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Caption salt cedar, tamarisk (Tamarix parviflora) �Location Leslie Gulch, OR�Date May 12, 2007�Credit Clinton Shock�Species Tamarix parviflora
T. parviflorainvading the Lower Owyhee River, OR, 2007
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Caption salt cedar, tamarisk (Tamarix parviflora) �Location Lower Owyhee River, OR�Date May 24, 2007�Credit Clinton Shock�Species Tamarix parviflora
Mediterranean sage: Salvia aethiopis
Eric Coombs, O
DA
Eric Coombs, O
DA
Eric Coombs, ODA
Mediterranean Sage (Salvia aethiopis )
Clary Sage: Salvia sclarea
Patterson’s Curse: Echium plantagineum
Patterson’s Curse (Echium plantagineum)
Leafy Spurge: Euphorbia esula
Leafy Spurge (Euphorbia esula)
Myrtle spurge: Euphorbia myrsintes
BS ThurnerHof
BS Thurner Hof
Myrtle spurge (Euphobia myrsintes)
Yellow Star Thistle: Centaurea solistialis
Yellow Star Thistle (Centaurea solistialis)
Wendy VanDyk Evans, Bugwood,org
Yellow Toadflax: Linaria vulgaris
Dave Pow
ell, USFS
John Cardina, Ohio State University, Bugwood,org
John Cardina, Ohio State University, Bugwood,org
Steve Dewey, Utah State University, Bugwood,org
Elizabeth Bella, USFS
Dalmatian toadflax: Linaria dalmatica
Orange Hawkweed: Hieracium aurantiacumMichael Shephard, USDA Forest Service
Orange Hawkweed: Hieracium aurantiacum
Orange Hawkweed: Hieracium aurantiacum
Michael Shephard, U
SDA Forest Service
Orange Hawkweed (Hieracium aurantiacum)
Spanish Broom: Spartium junceumPhotos: Michael L. Charters
Scotch Broom: Cytisus scoparius
French Broom: Genista monspessulana
But wait! There’s MORE!
Herb Robert: Geranium robertianum
Photo: University of G
eorgia
Fennel: Foeniculum vulgare
Photo: JohnathanJ. Stegem
an
Bachelor’s button: Centaurea cyanus
Camelthorn: Alhagi maurorum Richard Old
Only you can prevent the invasion!
What can Green Industry Professionals Do?
Know the enemy & teach others about them
Research new stock before you order it
Grow, sell or design for native & non‐invasive plants wherever possible
Help the public with information on treatment
What can Green Industry Professionals Do?
Get involved in landscape management ordinances where appropriate
Get involved in weed management boards
Help support local weed identification and education efforts
Help support research focused on invasives, control and alternatives
What can industry professionals do?
Watch for hitchhikers in nursery stock
Use weed‐free soil and mulch
Watch introductions for aggressive behavior
Discourage use of commercial wildflower or other mixes.
Check clothes, vehicles, equipment, & pets
Commercial Wildflower or Plant Border Mixes (AKA “Meadow in a Can”)
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UW studied established that upwards of 98% of all commercial wildflower mixes had some invasives in them. Border mixes too had problematic plants. No mixes were entirely clean. Best to just avoid them altogether!
If you have a known invasive (but a client can’t part with it)
Deadhead faithfully
Use root barriers
Dispose of plant material properly—bagged in the garbage or burned (completely)
Contain it, control it, or cage it!
For Water Gardens
Always wash new introductions (think snails)
Keep water gardens separate from native waters
Never dump water garden materials or water into native waters
Research plants for invasive potential—many commonly used aquatics are!
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Water gardens are particularly problematic—as the plants and organisms in them are almost impossible to control once they are released into the environment. Treat them with care.
Some Resources
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Use the PLANTS database to assess a plants invasiveness.
http://plants.usda.gov/java/noxiousDriver
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One resource for
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This is an excellent resource for anyone in the business of growing plants.
Invasive Spp. Web ResourcesAll of this information located at: bit.ly/is4gipOregon Invasive Species Councilwww.oregon.gov/OISC/Oregon Invasive Species Hotline:oregoninvasiveshotline.org/National Invasive Species Clearinghouse: www.invasivespeciesinfo.govUSDA PLANTS Database: plants.usda.gov/index.htmlWA State Noxious Weed Board: www.nwcb.wa.gov/index.htmIdaho Weed Awareness:idahoweedawareness.net/index.htmlCalifornia Invasive Plant Council:www.cal‐ipc.org Be Plantwise:www.beplantwise.org/
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The top link leads to the rest—and I’ve handed out a sheet with that information on it.