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6) Management
d) Eradication
Concerns about eradication:
•
Not believed to be possible in most cases
•
May be very costly
•
May entail collateral damage
Example: fire ant eradication attempts in SE US
exacerbated invasion by killing more natural enemies than
fire ants
6) Management
d) Eradication
Feasibility
6) Management
d) Eradication
Feasibility:
• Biological characteristics
Easier to eradicate
Habitat specialist
Large size, conspicuous
Trees, shrubs
No soil seed bank
Short dispersal distance
Harder to eradicate
Habitat generalist
Small or cryptic
Other growth forms
Persistent soil seed bank
Long distance dispersal mechanisms
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate
• Cost increases exponentially with area
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
• Widespread support and cooperation
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
• Widespread support and cooperation
• Governmental authority may be needed to overcome vocal
public groups
• Example: removal of Eucalyptus from Angel Island: public
groups complained of “brutality” and “eucalyptus-phobia”
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
• Widespread support and cooperation
• Prevent re-invasion
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
• Widespread support and cooperation
• Prevent re-invasion
• Low populations, small areas
6) Management
d) Eradication
Eradications have been successful:
• Diseases (smallpox, yellow fever)
• Animals (vertebrate and invertebrate)
• Especially on islands (e.g. Nutria eliminated from Britain)
• Examples of eradications from continental areas too (e.g.
african giant snail from FL and QLD)
6) Management
d) Eradication
Eradications have been successful:
• Diseases (smallpox, yellow fever)
• Animals (vertebrate and invertebrate)
• Especially on islands (e.g. Nutria eliminated from Britain)
• Examples of eradications from continental areas too (e.g.
african giant snail from FL and QLD)
Plants eradicated less frequently, but:
• Witchweed (Striga asiatica) in Carolinas drastically reduced
• Asian common rice (Oryza rufipogon) in Everglades National
Park (0.1 ha)
• Karoo thorn (Acacia karoo) in W.Aust.
• Taurian thistle (Onopordium tauricum) VIC
• Witchweed and rice are two of seven eradication projects
sponsored by APHIS through 1993 (others less successful)
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• Detected in Idaho in 1969 (18 ha infested)
• By 1981 covered 9000 ha and listed as federal noxious weed
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• Detected in Idaho in 1969 (18 ha infested)
• By 1981 covered 9000 ha and listed as federal noxious weed
• 1981 eradication feasibility study launched. Initial biological
evidence indicated high probability of success.
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• Detected in Idaho in 1969 (18 ha infested)
• By 1981 covered 9000 ha and listed as federal noxious weed
• 1981 eradication feasibility study launched. Initial biological
evidence indicated high probability of success.
• Study not completed until 1988 and task force to plan the
eradication project did not convene until 1991
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• Detected in Idaho in 1969 (18 ha infested)
• By 1981 covered 9000 ha and listed as federal noxious weed
• 1981 eradication feasibility study launched. Initial biological
evidence indicated high probability of success.
• Study not completed until 1988 and task force to plan the
eradication project did not convene until 1991
• By 1991 crupina had spread to CA, OR, and WA, and
dominated 25,000 ha. Task force decided not to act because of
possible negative impact of herbicide on salmon.
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Introduced in 1990 as drought tolerant forage
• Recognized in 1992 as weed, and eradication began (herbicide)
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Introduced in 1990 as drought tolerant forage
• Recognized in 1992 as weed, and eradication began (herbicide)
• By 1993 plant had spread 900 linear km and affected 3200 ha.
• By 1995 infestation reduced to 139 ha
• By 2000 infestation reduced to 5 ha
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Problem recognized and controlled early (successful)
• Caulerpa taxifolia
• Anderson, L. 2005. California’s reaction to Caulerpa taxifolia: a
model for invasive species rapid response. Biological invasions
7:1003-1016.
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Problem recognized and controlled early (successful)
• Caulerpa taxifolia
• Anderson, L. 2005. California’s reaction to Caulerpa taxifolia: a
model for invasive species rapid response. Biological invasions
7:1003-1016.
• Placed on noxious weed list in 1999 (due to history in
Mediterranean)
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Problem recognized and controlled early (successful)
• Caulerpa taxifolia
• Anderson, L. 2005. California’s reaction to Caulerpa taxifolia: a
model for invasive species rapid response. Biological invasions
7:1003-1016.
• Placed on noxious weed list in 1999 (due to history in
Mediterranean)
• Discovered at Agua Hedionda lagoon June 12, 2000.
6) Management
d) Eradication
Examples:
• Crupina vulgaris (common crupina)
• 10 years after feasibility study project abandoned (unsuccessful)
• Kochia scoparia (summer cypress) in W. A.
• Problem recognized and controlled early (successful)
• Caulerpa taxifolia
• Anderson, L. 2005. California’s reaction to Caulerpa taxifolia: a
model for invasive species rapid response. Biological invasions
7:1003-1016.
• Placed on noxious weed list in 1999 (due to history in
Mediterranean)
• Discovered at Agua Hedionda lagoon June 12, 2000.
• Containment and treatments began 17 days after discovery
• Rapid response and ready resources ($2.12 million/year) =
containment and near eradication in 2005.
6) Management
d) Eradication
Feasibility:
• Biological characteristics: habitat specific; poor dispersal
• Sufficient resources allocated: Eradicate AND restore
• Widespread support and cooperation
• Prevent re-invasion
• Low populations, small areas
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• Deplete seed banks
• Find last few individuals
• Last 1% of eradication costs as much as first 99%
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking? (Regan et al 2002 Ecology Letters)
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking? (Regan et al 2002 Ecology Letters)
• A set time since detection (3 years, 5 years, longevity of
seedbank)
• Once population is below an arbitrary threshold (1%, 5%)
• Dynamic programming ‘cost-benefit’ approach: stop monitoring
and treating when the cost of doing so outweighs the benefits of
finding a plant
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking? (Regan et al 2002 Ecology Letters)
• A set time since detection (3 years, 5 years, longevity of
seedbank)
• Once population is below an arbitrary threshold (1%, 5%)
• Dynamic programming ‘cost-benefit’ approach: stop monitoring
and treating when the cost of doing so outweighs the benefits of
finding a plant
Plant eradication requires long-term funding (10+ years) – end
of funding = end of project
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success? (Panetta 2007 Diversity &
Distributions)
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success? (Panetta 2007 Diver & Distrib)
• Three criteria:
Delimitation: how well do you know the extent and location of
the invasion?
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success? (Panetta 2007 Diver & Distrib)
• Three criteria:
Delimitation: how well do you know the extent and location of
the invasion?
Containment: Have new invasions arisen outside the identified
area for eradication? (containment failure)
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success? (Panetta 2007 Diver & Distrib)
• Three criteria:
Delimitation: how well do you know the extent and location of
the invasion?
Containment: Have new invasions arisen outside the identified
area for eradication? (containment failure)
Extirpation: active management reducing live individuals and
seed production; monitoring of site once no live plants
found. Monitor sites at intervals matching the juvenile
period of the plant for maximum power
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success?
• How likely is the plant to re-invade?
• Eradication on islands more successful because reinvasion less
likely
• Ready source of seed/propagules make persistent eradication
unlikely – e.g. watermilfoil elimination from a lake with a public
boat ramp may be futile
• Intentional subversion – Johnny Weedseed in Golden Gate
Park
6) Management
d) Eradication
Additional considerations
• Persistent effort may be necessary
• When do you stop looking?
• How do you monitor success?
• How likely is the plant to re-invade?
• Is restoration possible?
• Removal of invasive may leave an ‘open niche space’ – ripe for
invasion of something else or expansion of weeds already
present
• Re-invasion may be more likely if a stable community is NOT in
place
6) Management
d) Eradication
Simberloff, D. 2003. Eradication – preventing invasions at the outset.
Weed Science 51:247-253.
Tradeoff: Eradication vs. maintenance management
Eradication: complete removal (or less commonly substantial reduction
and control) of pest species in a specified area
Maintenance management: controlling the invader at a tolerably low
level. Involves chemical, mechanical and biological control and
ecosystem management