A weed is a plant growing where it is not
wanted.
Introduction
Weed control
Weeds have uses
How do weeds get into bushland
Weeds are here to stay
Introduction
There are many weeds growing along Kedron
Brook. Most are non-native plants. Trees like Camphor laurel ( Cinnamomum
camphora) and Chinese celtis (Celtis sinensis) were planted in gardens
many years ago. Today, birds spread the seed and these germinate in the
moist environmental near the Brook. The trees grow into dense thickets
that prevent the growth of other plants.
Weeds also change the habitat and food
sources available to native fauna. Replacement of native flora by
weeds can result in the loss of a species of fauna from that area of
the catchment.
When introduced plants replace the diverse
natural communities, they are considered weeds. Many shrubs once
occurring in bushland have disappeared from along Kedron Brook. Native
plants are replaced by thickets of Lantana ( Lantana camara) in the upper
catchment, and by Japanese sunflower (Tithonia diversifolia) and grasses
in the middle and lower catchment.
Dense swards of grass occur along many parts
of Kedron Brook. Para grass Bracharia mutica is common at the waters
edge; Guinea grass (Panicum maximum) and giant Cane grass form some
impenetrable stands on the margins of the Brook.
Weed Control
Bushcare groups and Councils undertake weed
control along Kedron Brook. The extent of the weed problem is so great,
areas and plants treated must be prioritised. We don’t have enough
resources to do it all.
Details of weed identification, recording, and prioritisation for removal in relation to legislative requirements and authoritive recommendations are given in a separate web page, Weed Identification and Control Project. Plants routinely targeted for weed control in bush management actives along Kedron Brook are briefly described below.
Madeira vine
Madeira vine (Anredera cordifolia) is an
aggressive smothering vine that can grow from just small section of
leaves, stems or roots. The vine is common in gardens and bushland in
established urban areas. Careful removal of all parts of the plant is
required.
Morning Glory
Morning Glory (Ipomoea cairica) is another
vine that will smother vegetation; small trees are vulnerable. It has a
strong extensive root system from which it will re-shoot if not removed
from a site. This vine is widespread in urban areas and is often seen
growing over abandoned sheds or other structures.
Singapore Daisy
Singapore Daisy is a spreading herb that
readily grows from sections of stem, which are easily dislodged from
the parent plant. This plant forms dense mats along sections of Kedron
Brook
Chinese celtis
Chinese celtis (Celtis sinensis) is a woody
tree; pigeons and other seed-eating birds disperse seeds. This woody
weed is well established in many parts of the lower catchment and
widespread elsewhere in Brisbane. Maintaining good native tree cover
will prevent invasion of this species into bushland, removal of small
Chinese celtis before they flower will prevent further spread.
Guinea grass and Para
grass
Guinea grass (Panicum maximum) and Para grass
(Bracharia mutica) are widespread on land that has been modified and the
original vegetation removed. These grasses are typical of such
‘disturbed’ areas. Mechanical control is best in large swards, however
this removes potential fauna habitat. The treated area must be
replanted and stabilised immediately after grass removal to prevent
further weed invasion or erosion.
Japanese sunflower
Japanese sunflower (Tithonia diversifolia) forms dense thickets several metres high. The plant produces many seeds
and rapidly colonises new areas. Plant removal prior to flowering will
prevent further spread. The Japanese sunflower is not tolerant of very
dry periods. Native plants may get an edge on this shrub during drought.
Weeds do have some uses
In many areas, particularly hillslopes and
stream banks, the presence of some vegetation (even weeds) is better
than bare soil. A vegetation cover on the ground helps protect and bind
the soil. Removal of weeds will expose soil to erosion until new
vegetation is established.
Weeds can provide habitat for fauna but is
not as good as the native flora. Cisticolas are small birds that live
in the grassy margins along the stream. Swards of Para grass are used
for nesting and hiding, the birds feed on the grass seeds.
Lantana can offer shrubby cover for
bandicoots, ground-dwelling birds and reptiles.
In the middle reaches of the Brook, family
groups of finches feed on seeds of the herbaceous weed Thickhead
(Crassocephalum crepidioides). The finches nest in extensive Para grass
stands nearby.
How do weeds get into
bushland?
Most of the weeds occurring along Kedron
Brook have been introduced from urban gardens. Many weeds flower and
seed profusely, or can shoot from parts of the stem. Seeds and stem
parts may be washed by stormwater into the Brook, some seed is blown
across the landscape on the wind. Birds and bats disperse some weeds
but people are probably more important. When soil, machinery and garden
clippings are moved weed seeds can hitch a ride. Never dump soil, lawn
clippings or other refuse in bushland.
One of the most insidious ways of
introducing weeds to bushland is through the dumping of garden refuse.
This is material people don’t want in their backyards, it is even less
desirable in the local bushland or stream.
Such dumping often occurs near newly
developing urban areas or where properties directly abut the stream.
Weeds are here to stay
There are some weeds that may persist in
bushland without a detrimental effect on natural ecosystems most of the
time.
Where weeds threaten bushland remnants or
natural biodiversity, Bushcare groups and others work towards weed
removal. An important component of weed removal is replacement of the
plants with native plants. This
- helps protect the soil
- provides fauna with resources in the
future and
- increases the natural biodiversity of an
area
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