(chris) 21. Alien plant invasions Flashcards

1
Q

Not all alien plants become invasive

  • Chessnut
  • Fennel

(Introduced by Romans to Britain)

A

Chestnut (friendly alien species, doesn’t expand)

Fennel (grows like a weed, quite invasive)

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2
Q
A
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3
Q

Two most invasive plant species in NZ?

A

Pine

&

Understorey plant

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4
Q

Alien Plant

A

Many cultivated plants - Strawberrys, Parsnips

Presence due to intentional or accidental introduction as result of human acitivity (exotic plant)

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5
Q

Naturalized plants

A

Eucalyptus spp.,

Strawberrys/Parsnips/Avocados

  • Aliens that sustain populations over many life cycles without direct human intervention.
  • Most offspring recruited close to parents; do not necessarily invade natural, semi-natural or human-made ecosystem.
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6
Q

Invasive

A

Gorse

Naturalized plants producing reproductive offspring in large numbers, often at large distances from parents plants.

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7
Q

Weeds

A

Manuka on farmland

Plants (not necessariley alien) frowing where they are not wanted, and which have detectable economic or environmental effects.

(Manuka originally seen as weed)
-worth carbon credits

-mankes manuka honey $$

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8
Q

Envrionmental weeds

A

Privet

Alien plants that invade natural vegetation

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9
Q

Transformers

A

Pinus contorta

Subset of invasive plants that significantly change the character, condition, form or nature of ecosystems.

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10
Q
A
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11
Q

Why care about plant invasions?

A
  • Displacement of native species
  • Displace habitat of ground-nesting birds (dotterels,stilts,terns)
  • Also allow predators to ambush birds as they block visual line of sight.
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12
Q

In Australian savanas, invasive grasses increase..

A

fire intensity.

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13
Q

Alteration of ecosystem services..

A

Disruption of toursim

(lamenting the spread of wild conifers)

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14
Q

What determines invasion “success” ?

A
  • Climatic suitability
  • Residence time
  • Propagule pressure
  • Dispersal traits
  • Reproductive traits
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15
Q

Familiarise

Dispersal - Get to New Zealand

Physiological - Deal with environment factors

Biotic - Deal with competition (herbivores/parasites)

A
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16
Q

Do plant traits explain invasion?

(weedy plants)

A

Weedy traits:

  • fast growing
  • associated with disturbed habitats

Plants reported as invasive are consistantly faster-growing than non-invasive congeners.

Short-term bias in data. because invasions by slow-growing shade tolerent species may take longer to make an impact?

YES…BUT!

But invasive plant in NA found to grow faster than native trees of similar shade tolerance, how? Because it has escaped it natural predators perhaps from home environment.

17
Q

Escape from specialist enemies in new environment means the exotic plant…

A

..is subject to less herbivore pressure than its new neighbours, giving it a competitive advantage,

18
Q

Familiarise

A
19
Q
A
20
Q

Weevils introduced to control gorse.

(weevils eat seeds)

A

Lifecycles do not line up

21
Q

Introduced to N.A

A
22
Q
A
23
Q
A