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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:

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Presentation on theme: "6)Management d)Eradication Concerns about eradication: Not believed to be possible in most cases May be very costly May entail collateral damage Example:"— Presentation transcript:

1 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

2 6)Management d)Eradication Feasibility

3 Feasibility: Biological characteristics 6)Management d)Eradication 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

4 Feasibility: Biological characteristics: habitat specific; poor dispersal Sufficient resources allocated: Eradicate Cost increases exponentially with area 6)Management d)Eradication

5 Feasibility: Biological characteristics: habitat specific; poor dispersal Sufficient resources allocated: Eradicate AND restore 6)Management d)Eradication

6 Feasibility: Biological characteristics: habitat specific; poor dispersal Sufficient resources allocated: Eradicate AND restore Widespread support and cooperation 6)Management d)Eradication

7 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

8 Feasibility: Biological characteristics: habitat specific; poor dispersal Sufficient resources allocated: Eradicate AND restore Widespread support and cooperation Prevent re-invasion 6)Management d)Eradication

9 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

10 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

11 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

12 Examples: Crupina vulgaris (common crupina) 6)Management d)Eradication

13 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

14 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

15 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 )Management d)Eradication

16 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

17 Examples: Crupina vulgaris (common crupina) 10 years after feasibility study project abandoned (unsuccessful) 6)Management d)Eradication

18 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

19 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

20 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 California’s reaction to Caulerpa taxifolia: a model for invasive species rapid response. Biological invasions 7: )Management d)Eradication

21 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 California’s reaction to Caulerpa taxifolia: a model for invasive species rapid response. Biological invasions 7: Placed on noxious weed list in 1999 (due to history in Mediterranean) 6)Management d)Eradication

22 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 California’s reaction to Caulerpa taxifolia: a model for invasive species rapid response. Biological invasions 7: Placed on noxious weed list in 1999 (due to history in Mediterranean) Discovered at Agua Hedionda lagoon June 12, )Management d)Eradication

23 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 California’s reaction to Caulerpa taxifolia: a model for invasive species rapid response. Biological invasions 7: Placed on noxious weed list in 1999 (due to history in Mediterranean) Discovered at Agua Hedionda lagoon June 12, Containment and treatments began 17 days after discovery Rapid response and ready resources ($2.12 million/year) = containment and near eradication in )Management d)Eradication

24 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

25 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

26 Additional considerations Persistent effort may be necessary When do you stop looking? (Regan et al 2002 Ecology Letters) 6)Management d)Eradication

27 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

28 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

29 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

30 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

31 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

32 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

33 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

34 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

35 Simberloff, D Eradication – preventing invasions at the outset. Weed Science 51: 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 6)Management d)Eradication


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