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Invasive Species. September 5 th , 2007. Announcements:. Check out Case Studies posted on website (if you forgot which group you are in, scroll through to find your name, or ask me) Come prepared for class discussion tomorrow Background Field Trip Questions: now posted

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invasive species

Invasive Species

September 5th, 2007

  • Check out Case Studies posted on website (if you forgot which group you are in, scroll through to find your name, or ask me)
    • Come prepared for class discussion tomorrow
  • Background Field Trip Questions: now posted
  • Field Trip Waiver Forms: I need you to sign them
  • Field final: will be passed out tomorrow
summary of monday
Summary of Monday:
  • How do communities change?
    • Succession
      • Primary vs. Secondary
      • Who wins at the beginning? Who winds at the end?
        • Facilitation: biotic/abiotic interactions
          • Early colonizers vs. Pine vs. Oak
          • Grasses on sand dunes, eelgrass
        • Acceleration
      • Climax communities?
      • Plant vs.Animal Succession?
      • Intermediate Disturbance Hypothesis
        • Role of fire in Chaparral Biome
why study invasive species
Why study invasive species?
  • Invasive species are the second greatest threat to conservation of biodiversity
  • economic consequences (good and bad)
  • human health consequences
invasive species glossary
Invasive Species Glossary
  • native: an organism that is living in its home environment
    • Endemic: organism that is only found in/confined to a particular location
  • exotic
  • non-native originally from a different location
  • foreign/alien
  • naturalized: a non-native that has become a part of its new environment
  • invasive: a non-native that has spread to become a dominant member of its new environment
  • weed: an invasive species of plant that causes
  • environmental or economic problems
  • - Noxious weed: legally designated as a pest
how do non native species arrive
How do non-native species arrive?
  • Accidentally
    • seeds
    • parasites
    • unintended cargo
  • Deliberately
    • food
    • timber
    • pets
    • biocontrol

Data source: Eurostat. Source of figure: CNT, 2004

Data source: US Department of Transportation, 2004

who are these invaders
Who are these invaders?
  • Plants
  • Animals
  • Microorganisms
what makes an invader successful

What made the green

crab successful?

What makes an invader successful?
  • r-strategists
    • grow quickly
    • produce many offspring
    • short generation time
  • good dispersion
  • generalists: highly adaptable to new conditions
    • broad geographic range in native environment
    • broad diet
  • It has not coevolved with members of its new environment
what makes a community vulnerable to invasion
What makes a community vulnerable to invasion?
  • human disturbance
  • early succession
  • climate similar to native habitat
  • absence of predators or pathogens
    • wrong ones for the invader
    • no predators or pathogens at all - islands
what do invasive plants do
What do invasive plants do?

Change ecosystem structure

  • fire suppression/enhancement
    • grassland  shrubland
    • And vice-versa
  • Change nutrient cycling
    • Spartina alterniflora
  • Change physical structur of landscape
    • European beachgrass
  • use up limiting resources, such as water, light
    • riparian zone  desert
    • woodland  kudzu-dominated land
grassland to shrubland
Grassland to shrubland

Changes fire regime!

shrubland to grassland
Shrubland to Grassland

Changes fire regime!

woodland to kudzuland
Woodland to Kudzuland

Can you guess its strategy?

what do invasive animals do
What do invasive animals do?

Change foodweb structure

  • Hyperpredation
  • drive out native competitors

and prey

a case study zebra mussels
A case study: zebra mussels
  • native to Russian lakes
  • introduced to North America in 1985 from bilge of a ship
  • after <1 year, can produce 1,000,000 eggs
  • large colonies clog pipes
  • very efficient filterers
    • clear water
    • eliminate native species
management options
Management Options
  • Do nothing
  • Understand life strategy
    • Vulnerabilities, limiting factor
  • Predict where it will invade, rate of spread, during what time periods….
    • Remote sensing
    • Mathematical models!

Coalition Drops Black Rat Poison on Anacapa Island

by Rebecca Turek - Staff WriterThursday, December 6, 2001

  • Physical control
  • Chemical control
  • Thermal control
  • Biological control
    • Predator
    • Virus
    • Grazing
biological control lessons from the outback
Biological control: lessons from the Outback
  • Cane toads
  • Rabbits
    • 1950’s: myxoma virus
    • 1990’s: Calcivirus
  • Success stories:
    • Schisto.
how can we avoid invasive species and preserve biodiversity
How can we avoid invasive species and preserve biodiversity?
  • “Co-habitable” land use
    • Land uses consistent with biota
      • Give up the green lawn!
      • Organic/crop rotation based agriculture (but what is the cost?)
  • Habitat enhancement
    • Variation of landscape
    • Restore disturbance regimes
  • Re-introduction
  • Laws and Regulations
pop quiz

Pop Quiz!

Which plant/animal would you say is the MOST invasive???

questions to ponder
Questions to Ponder:
  • How long do you have to inhabit an area to be a native?
  • What point in time should we restore to?
  • Is fighting invasives a losing battle? What are the costs of doing nothing?
where is biodiversity loss most prominent
Where is biodiversity loss most prominent?

Conservation International: Biodiversity Hotspots

CI quantified by number of endemic plant species and threat

assessing biodiversity
Assessing Biodiversity
  • Indicator species: Species that are present only under strict environmental conditions
    • Can be used to detect healthy/unhealthy ecosystems
    • Example: steelhead, certain diatoms
  • Species diversity/richness: number of species in sample

-diversity: number of species within a single habitat type

-diversity: difference in species composition between habitats

  • Species evenness: equality of relative abundance
    • Unevenness might indicate unhealthy ecosystem
  • Biodiversity Index
shannon wiener biodiversity index
Shannon-Wiener Biodiversity Index


H = the Shannon-Wiener biodiversity index

pi = proportion of each species in the sample (relative abundance)

loge = the natural log of pi

s = the number of species in the community (species richness)

H(Community II) = -(.3*ln(.3)+.07*ln(.07)+.1*ln(.1)+.5*ln(.5)+.03*ln(.03))

how to protect biodiversity
How to Protect Biodiversity?
  • Protect Species
    • Endangered Species Act
    • Classic Fisheries Managment
  • Protect Habitat
    • Reserves
    • Conservation Easements
    • Marine Reserves
species protection
Species Protection
  • Minimum Viable Population (MVP)
  • Inbreeding, genetic drift
  • Genetic bottleneck
  • Minimum Viable Area—habitat protection
genetic bottleneck population loses much of its genetic diversity from a population decline
Genetic bottleneck-Population loses much of its genetic diversity from a population decline

Most genetic

diversity is


which species to protect
Which Species to Protect?
  • Umbrella species
  • Flagship species
  • Keystone species
habitat protection reserves
Habitat Protection: Reserves
  • One large or many small?
  • Shape?
  • Connectivity?
sloss debate single large vs several small
SLOSS Debate: Single Large vs. Several Small

Species-area curve

  • Management implications:
  • Small reserves: area = species
  • As area increases, diminishing returns

To consider:

Genetic exchange

Extinction events

Edge effects

Future Pressures


connectivity nodes and corridors
Connectivity: Nodes and Corridors

Is connectivity important in MPA’s?

habitat conservation management tools
Habitat Conservation Management Tools
  • Conceptual diagrams
  • Collaboration (with stakeholders, community)
  • Mathematical/computer models
  • GIS (Geographic Information Systems)
  • Remote sensing
  • Environmental Impact Reports
the new trend

The new trend……

Ecosystem Based Management (EBM)

"EBM looks at all the links among living and nonliving resources, rather than considering single issues in isolation . . . Instead of developing a management plan for one issue . . ., EBM focuses on the multiple activities occurring within specific areas that are defined by ecosystem, rather than political, boundaries."
 US Ocean Commission Report, 2004