Env 400 Ch. 10

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exotic

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which are also known as alien species, invasive species, non-indigenous species, and bioinvaders, are species of plants or animals that are growing in a nonnative environment. Alien species have been moved by humans to areas outside of their native ranges.

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invasive

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- an exotic species becomes invasive when the population starts to increase through reproduction that happens because there are no natural enemies in the new habitat

- are plants, animals, or pathogens that are non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause harm.

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invasive exotic

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why are some species more successful invaders than others?

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• Few natural enemies

– Predators

– Competitors

– Parasites and diseases

• High reproductive rate

• Long lived

• Good dispersal

• Generalists

• Pioneer species

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why are some ecosystems more susceptible to invasive than others?

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Microsoft Word - Areas at risk.doc Mountains, cliffs, bogs, dry grasslands and coniferous woodlands tend to resist alien invasion, while coastal andriverine habitats, where nutrient availability and disturbance can be high, are more prone to invasion by alien plants.Human-made habitats such as farmland and urban landscapes also facilitate the spread of alien plants. Besidesthese, the most invaded habitats include broadleaved deciduous forestry plantations, forest clearings or riversidewillow scrub habitats.

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what is "tens rule?"

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- states that out of 1,000 introduced species only 100 manage to escape into the wild, 10 establish there and only one will become a pest.

- Describes how approximately ten percent of species pass through each transition from being imported to becoming casual to becoming established, and finally becoming a weed

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how do species move? examples

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Stowaways

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1. Norway rat, black rat

2. Economic losses

3. Extinction of species on islands

4. Go unnoticed

Fig. 10.2

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B. Subsistence and Commerce

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1. Need for food

2. Colonists and domesticated plants

3. Exotic trees

4. Feral

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C. Recreation

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1. Sport hunters and anglers

2. Green river

3. Eugene Scheifflin

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D. Science

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1. Accidental escape

2. Gypsy moth

3. Genetic engineering

4. “super-weeds”

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E. Biological Control

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1. Can a bad situation become worse?

2. Eastern barred bandicoot

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F. Habitat Change

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1. Human-induced environmental changes

2. Welland Ship Canal

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impacts of invasive exotics:

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A. Predators and Grazers

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1. Stephen’s island

2. Brown Snake

3. Exotic fish

4. Introduced insects

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B. Parasites and Pathogens

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1. Human diseases

2. Avian malaria and avian pox

3. Biocontrol of gypsy moth

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C. Competitors

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1. Plants

2. Space, nutrient, light

3. Mobile animals

4. Gray squirrels

5. Exotic wasps

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D. Hybridization

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1. Inbreeds/hybrids

2. Mallard ducks

3. Genetic swamping

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E. Ecosystem Effects

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1. Productivity

2. Nutrient cycling

3. Soil and vegetation structure

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IV. Success Rates Why are some species more successful than others?“tens rule”Ecosystem of choiceDisturbed ecosystems