Download EnviroWeeds

• explain how habitat disturbance from
soil degradation can advantage
introduced species of plants and lead to
the reduction or elimination of native
flora and fauna species in affected areas
A
weed is a plant that is out of place.
 Native plants could be classified as a
garden weed if, for example, they were
growing in a vegetable garden.
 Environmental weeds are plants that are
growing outside of their natural habitat.
 Environmental
weeds have usually been
introduced into new locations.
 Most environmental weeds are introduced
from outside Australia e.g. Camphor Laurel,
Lantana
 Some environmental weeds are native to
different parts of Australia, e.g. Umbrella
Tree, Fishbone Fern.
 Some native plants have become
established in new habitats due to human
disturbance and become environmental
weeds, e.g. Sweet Pittosporum.
 Annuals
and groundcovers, e.g. Farmers
Friend, Fleabane. These tend to be
shortlived and only do short term damage
to an ecosystem.
 Vines, e.g. Madiera Vine, Cats Claw
Creeper. These can completely smother the
canopy of even established trees and cause
mid to long term habitat damage.
 Woody trees, e.g. Camphor Laurel, Privet.
These can permanently change the
ecosystem.
 Because
environmental weeds are
introduced into areas outside of their natural
habitat they don’t have many of the pests
and diseases that help keep native plants in
balance, e.g. seed predators, etc.
 Environmental weeds are often fast growing,
prolific seeders and fast germinating.
 Camphor Laurel is also allelopathic – oils
from its leaves can inhibit the germination of
native plants.
 Environmental
weeds rarely invade intact
habitats.
 The more degraded a habitat is, especially
through soil disturbance, the easier it is for
environmental weeds to become
established.
 Soil disturbance can remove the seed bank
of established native trees – some native
seeds can remain dormant for tens of years.
 Increased light levels will favour weeds in
rainforest habitats while lack of fire will tend
to favour weeds in sclerophyll habitats.
 Environmental
weeds tend to reduce the
diversity and abundance of native plants.
 Some weeds can replace native plants in
ecosystem processes, e.g. Camphor
Laurel has replaced native laurels in the
diet of many native birds.
 Through lower plant diversity some
faunal diversity may also be lowered, e.g.
reduction in specialist species.