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?
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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?
Plant to Plant: Direct Effects
Competition for resources, space Growth, repro.
Plant to Plant: Indirect
Competition for pollinators, dispersers Reproduction
Introduction of disease to native spp Survival
Change in Processes Growth, repro.
Disturbance, hydrology, food webs, nutrient cycling
Innate biology: Weediness, competitiveness, tolerance, preadaptation:
Enemy release/Biotic resistance:
Community invasibility: diversity, productivity, disturbance:
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
Traditional Strategies for Invasive Species
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 SALES
--Florida data from Lippincott & Hall 1996
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)
Female Cactoblastis ovipositingon Opuntia, linear egg mass attached to a cactus spine
Damage to Opuntia by Cactoblastis larvae,pad destroyed, plant open to infection
used to control Opuntia spp. around the world.
Before CactoblastisAfter Cactoblastis
This lodged the idea of biological control of weeds in the minds
of scientists and launched succeeding programs.