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Plant Ecology > Invasion Ecology > Flashcards

Invasion Ecology Flashcards

1
Q

Invasion Ecology

A

Not just invasive species
Whole new subject area studying the whole process of invasion
- Exponential increase in research and citations around early 1990’s

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2
Q

Invasion Process

A

Transport: Death/captivity or Successful Introduction
Establishment: Fail or Establish Successfully (Japanese Knotweed)
Spread: Remain Local (Holly/English Daisy) or spread
Impact: Low or High(Scotch broom and Daphne) (can depend on human perception such as blackberries are yummy!)

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3
Q

What is currently happening in the Comox Valley regarding Introduction?

A

Saltmarsh Cordgrass has been introduced from California and is replacing native Distichilis. Cordgrass is very aggressive.

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4
Q

Guam Invasion

A

Pre 1945: 25 species with 18 native and 7 introduced

1965: Addition of brown tree snake brought total species to 28 with 18 native and 10 introduced, major impacts on food web
1995: Introduction of brown tree snake sent food web to hell after the only predator was eliminated (preyed on each other), Total 12 species with 4 native and 8 introduced

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5
Q

What is the most major anthropogenic cause of invasion?

A

Shipping routes and abundant trade
Either purposeful or accidental
Many caused by Europe

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6
Q

Hub and Spoke Invasion Theory

A

A hub port is at the center (eg Vancouver) with primary invasion

  • From there, nearby ports can be invaded (Nanaimo, Victoria)
  • Other Sites for secondary invasion can occur on export routes from the hub port
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7
Q

When did invasions really start to exponentially accumulate in most places?

A

Later 1800’s as shipping significantly increased. Correlation.

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8
Q

4 main causes of adverse impact on native fish (ie salmon)

- What may surpass all of those traditional impacts?

A
  • Habitat Alteration (largest impact)
  • Harvest (over-harvest)
  • Hatcheries (Reduce genetic diversity)
  • Hydro-systems (small or large)
  • Non-indigenous species may exceed or equal the previous impacts
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9
Q

What is the U.S. ESA?

A

Endangered Species Act

  • A real Act that is enforced and has power in the courts
  • Number of invasive species correlates to more native fish added to the ESA
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10
Q

How are non-indigenous fish introduced?

What are the main introduced species that affect aquatic habitat?

A

Often purposefully for sport fishing purposes (Yummy)

  • Brook Trout
  • Walleye
  • American Shad
  • Freshwater Bass
  • Channel Catfish
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11
Q

Main problematic species that are not fish?

A
  • NZ Mudsnail
  • Siberian Freshwater Shrimp
  • Eurasion water Milfoil (Transported by boaters)
  • Purple Loosestrife (Shifts hydrology and plant composition, forming a monoculture)
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12
Q

Reconstruction of the 1500’s exploration by Sir Francis Drake

A
  • Easily transported marine inverts
  • B/c ship sat on bottom of bay at low tide (picking up sedentary bottom dwellers)
  • Most of these bays now have similar species composition - So which are the native ones? Most have naturalized
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13
Q

Where are the majority of invasive species found and why?

A

Temperate regions because there are more people (and potentially more land mass)
- Temperate regions are less extreme and easier to survive (introductions drop off as you go north from temperate areas)

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14
Q

Transportation routes and impacts

A

Most import routes are unidirectional

  • Pacific Asia & NA frequently exchange species
  • Areas around ports and islands are hit hardest b/c of the shipping
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15
Q

Hawaiian impacts

A
  • Six import routes, no exports (no Hawaiian endemics found elsewhere)
  • Most Hawaiian terrestrial endemics have disappeared
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16
Q

Modeling Invasibility

A

E = I x S
E - # exotics present (proportion of non-native species established is the sites invasibility, E)
I - # species introductions
S - Survival rate (establishment) of introductions

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17
Q

Components of # introductions

A

I = Ia + Ii
Ia - Accidental release (bilge waters)
Ii - Intentional release

18
Q

Components of Survival rate of introductions

A 
S = SvShScSm
S is establishment after accounting for:
Sv - Competition
Sh - Herbivory
Sc - Chance events
Sm - Maladaption
19
Q

I vs. S on Van Isle

A

Sometimes the # of introductions is enough to support the Establishment even with significant mechanisms such as competition, disturbance, life history, and climate

20
Q

Global patterns of Plant invasions

A
  • Non-native and Native species richness are weakly positively correlated (regardless of whether it is a mainland or island)
  • The plot is a list of species # and doesn’t account for abundance
  • Abundance is more important than list
  • There is a tipping point where natives become outcompeted (abundance issue)
21
Q

Propagule

A

Set of non-native individuals released into a new environment
- Can be seeds or clones

22
Q

What are the 3 components of propagule pressure?

A
  • # of individuals released per event
  • # of release events
  • Health of individuals released
23
Q

Propagule pressure: Health of individuals released

A

Ballast water Plankton

- Phytoplankton and zooplankton can survive for weeks on board a ship, but will die over time

24
Q

Propagule pressure: # of individuals released per event

A

More released = higher likelihood of establishment

- Ex. The release of insect in NZ to control Broom, more intros = larger population establishment

25
Q

Propagule pressure: # of release events

A

More frequent releases = greater proportion of establishments

26
Q

Propagule pressure and biological traits of birds introduced worldwide

A

Bird Traits:

  • Large body mass*
  • High annual fecundity*
  • Large geographic range*
  • Diet generalist*
  • Migratory tendency
  • Sexual dicromatism
  • indicates statistically significant correlation to intro success which may reflect human bias in choice release
  • Correlated success of an intro to propagule size
27
Q

Introductions to NZ

A

10th century: Polynesians brought 2 mammals (Maori Dog, Pacific Rat)
1769: Captain Cook brings goats
1792: Sealers and Whalers exhaust stocks over 20 year period. Introduced Norway Rat & Black Rat & mice
1840s: Large influx of European settlers brought the remaining terrestrial vertebrates (ex. Deer)
1851 - 1910: 26 recorded new introductions never found before

28
Q

Rodent introductions to NZ

A

Each of the introduced rat species (Pacific, Norway, Black) has unique trophic niche and food preference
- The 3 species covered all and devastated bird populations for seabirds, ground-nesters and even tree-nesters

29
Q

Deer introductions to NZ

A

Started in 1851 for sport hunting purposes

  • No natural predator
  • Forests evolved w/o deer, so introduction was devastating
  • Deer population rapidly expanded exponentially
  • Destruction of forests led to initiation of erosion problems
30
Q

Why are islands more invasible?

A

Access to ports, smaller space to invade, More coastline, and more opportunities due to shipping

31
Q

Disturbance Classifications

A
  • Natural vs. Anthropogenic
    eg. Wildfire vs Prescribed burn
  • Biotic vs. Abiotic
    eg. Prairie dog vs. deep plowed fields
  • Endogenous vs. Exogenous
    eg. Succession vs. Tree planting
    ie. Occurs by itself vs. intentional
32
Q

Definition of Disturbance

A

Any event in time that disrupts ecosystem community or population structure and changes resources, substrate availability or the physical environment

33
Q

Range of events and processes

A
  • Intensity (magnitude and severity
  • Frequency (mean # per unit time
  • Duration (temporal extent, how long does it last)
  • Predictability (regularity of the occurrence)
  • Distribution (size & spatial extent)
  • Synergism (does a disturbance precipitate or exacerbate further disturbances)
34
Q

Probability of community invasion

A

Within community resistance (Abiotic- Temp, water, light, disturbance level & Biotic- Species richness, competition, predation)
vs.
Propagule pressure (invasive supply eg. seeds)

35
Q

Probability of community invasions

- Effect of increased propagule supply

A
  • Probability of invasion increases w/ more propagule pressure (it only took 9 seeds for Broom to establish here)
  • Lose the biotic and abiotic resistance
36
Q

What happens post-invasion regarding probability of community invasion?

A
  • Previous invasion can facilitate conditions necessary for future arrivals
  • Eg. Broom facilitated Daphne
  • Community resistance decreases after invasion making the community more susceptible
  • Once the resistance decreases enough and probability increases the community is destroyed and can no longer fight back
  • Even if introductions stop the community is so damaged it is significantly more susceptible
37
Q

Allee effect

A

For smaller populations, the reproduction and survival rates of individuals increases with population density, although this effect usually disappears as increased intraspecific competition occurs

38
Q

Theory of fluctuating resource availability

A
  • Uptake/supply isocline (resistance to invasion isocline)(uptake=supply)
  • Invasibility is highest w/ increase supply and under the isocline (less uptake)
  • Pulse the system with increased nutrients, and natives will not respond in uptake so invasives move in to take advantage of nutrients
39
Q

Resource uptake vs. supply plot

A

Gross resource supply vs. Resource uptake

  • Pulse: Increase supply, no change to uptake = Run-off/eutrophication
  • Decline: No change in supply w/ decreased uptake = Overgrazing/herbivory
  • Both: Increase nutrients, decrease uptake = Agricultural problem from both overgrazing & over-fertilizing (biggest disturbance)
40
Q

Theory of fluctuating resource availability cont.

A
  • Community susceptibility to invasion increases as resource availability increases (the difference btwn gross resource supply and resource uptake)
  • ie Competition for available resources is primary driver of vegetative succession
  • Resource availability can increase due to a pulse in resource supply, a decline in resource uptake, or both may occur (highest disturbance)
  • Resource availability increases invasability
41
Q

Watershed disturbance example

A
  • Many variables
  • More disturbed the watershed was increased the # of non-natives
  • Urban development, agriculture were the most important disturbance forces and correlated together

Plant Ecology (12 decks)

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