invasive species ii: management bio 415/615. questions 1. what is the ‘homogeocene’? 2. when is...
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Invasive species II:management
Bio 415/615
Questions
1. What is the ‘homogeocene’?2. When is the best time to ‘stop’ an
invader, in terms of management cost and success?
3. Why do Barney & DiTomaso (2008 Bioscience) suggest domestication of plants for biofuels creates a greater invasion risk than food crop domestication?
4. What did the Cactoblastis moth do to prickly pear cacti in Australia?
What harm do invaders cause?
Melaleucain S Florida
• Transpiration higher
• Lower water table• Hotter fire• Deeper burn in
organic matter, more severe effects
Plant to Plant: Direct EffectsCompetition for resources, space Growth, repro.Hybridization Reproduction
Plant to Plant: IndirectCompetition for pollinators, dispersers ReproductionIntroduction of disease to native spp Survival
Ecosystem EffectsChange in Processes Growth, repro.Disturbance, hydrology, food webs, nutrient cycling
Invasive Plant Effects in Natural Areas
Economic & other impacts to human well-being
• Forestry, agriculture• Boating, fishing, swimming, water supply• Allergies, toxins• Fire: human life and property• Cost of control• Environmental cost of toxic chemical use
• Nature Conservancy suggests annual costs of invaders are about 5% of world economy; in US $120billion/yr
• Land ‘infested’ with invaders take up space of CA?
The Homogeocene
• Globally, species diversity is going down. Locally, species diversity is going up. What does this mean for communities?
Rahel 2000Science 288:854-856
% Introduced% Introduced
Rahel 2000Science 288:854-856
AllAllExtirpationsExtirpationsIntroductionsIntroductions
Non-indigenous birds in HawaiiLockwood 2006. Biol. Invasions 8:449-457.
Invasion hypotheses:What to do?
Innate biology: Weediness, competitiveness, tolerance, preadaptation:
Enemy release/Biotic resistance:
Community invasibility: diversity, productivity, disturbance:
Availability: Rapid evolution:
Invasion hypotheses:What to do?
Innate biology: Weediness, competitiveness, tolerance, preadaptation: SOME SPP ARE INVASIVE, PROHIBIT THROUGH RISK ASSESSMENT, DEVELOP STERILE CULTIVARS—YES
Enemy release/Biotic resistance: MANY SPP ARE INVASIVE, ESPECIALLY THOSE WITH HIGH GROWTH RATES AND HIGH RESOURCE DEMANDS, ASSESS ROLE OF ENEMIES—YES, but research is demanding
Community invasibility: diversity, productivity, disturbance: SOME COMMUNITIES ARE INVASIBLE, MANAGE AGAINST INVASION, MANAGE AGAINST DISTURBANCE AND HIGH RESOURCE LEVELS, MANAGE FOR HIGH NATIVE RICHNESS—SOMETIMES, but not always feasible (disturbance, low richness, high resources are natural, too)
Availability: MOST SPP ARE INVASIVE, REDUCE AVAILABILITY—YES Rapid evolution: RESTRICT GENETIC DIVERSITY—YES, but seems
unlikely given horticultural interest in selection
Other Countries
Eradication
USATraditional Strategies
for Invasive Species
Prevention
Preclearance
Exclusion
Detection
Containment
Control
Management costs accumulate:
• Prevention• Early detection, narrow window near
entry point for eradication• Controlling in selected locations• Bearing the cost of change
Prevention: Australian Weed Risk Assessment
http://www.daff.gov.au/ba/reviews/weeds/system/weed_risk_assessment
Pheloung et al. (1999) tested the WRA against 370 plants present in Australia; rate of rejection of invaders was 100% and rate of false positives was low (7%)
INVASIVES ARE A SMALL % OF EXOTICS
INVASIVES ARE A SMALL % OF SALES
--Florida data from Lippincott & Hall 1996
Taxa %
Exotics in cultivation 25,000 --
Naturalized 1,000 4
Weedy 750 3
Possible natural area impacts 125 0.5
Sold in the trade today 40 0.16
Economically important 13 0.05 (33%/40)
Islands and eradication of exoticsKrajick 2005. Science 310:1410-1413.
Eradication over large areas
Classical Biocontrol: Cactoblastis on Opuntia
Damage to Opuntia by Cactoblastis larvae,pad destroyed, plant open to infection
Female Cactoblastis ovipositingon Opuntia, linear egg mass attached to a cactus spine
Following this stunning success, C. cactorum has been widely used to control Opuntia spp. around the world.
Before Cactoblastis After Cactoblastis
This lodged the idea of biological control of weeds in the mindsof scientists and launched succeeding programs.