(chris) 21. Alien plant invasions Flashcards
Not all alien plants become invasive
- Chessnut
- Fennel
(Introduced by Romans to Britain)
Chestnut (friendly alien species, doesn’t expand)
Fennel (grows like a weed, quite invasive)
Two most invasive plant species in NZ?
Pine
&
Understorey plant
Alien Plant
Many cultivated plants - Strawberrys, Parsnips
Presence due to intentional or accidental introduction as result of human acitivity (exotic plant)
Naturalized plants
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.
Invasive
Gorse
Naturalized plants producing reproductive offspring in large numbers, often at large distances from parents plants.
Weeds
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 $$
Envrionmental weeds
Privet
Alien plants that invade natural vegetation
Transformers
Pinus contorta
Subset of invasive plants that significantly change the character, condition, form or nature of ecosystems.
Why care about plant invasions?
- 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.
In Australian savanas, invasive grasses increase..
fire intensity.
Alteration of ecosystem services..
Disruption of toursim
(lamenting the spread of wild conifers)
What determines invasion “success” ?
- Climatic suitability
- Residence time
- Propagule pressure
- Dispersal traits
- Reproductive traits
Familiarise
Dispersal - Get to New Zealand
Physiological - Deal with environment factors
Biotic - Deal with competition (herbivores/parasites)