Factors Affecting Flora Conservation - Victorian Environmental ...

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(a) background weeds, which occur over
extensive areas but which are rarely
dominant; the presence of these species
does not normally threaten indigenous
species, and
(b) swampers, which tend to occur in dense,
often localised swards, out-competing
and replacing indigenous species.
Weed species in either category can be
controlled or eradicated in a given area with
suftlcient resources. However, the second
category are usually given the highest
priority where weed management resources
are limited.
Given the extent of the weed problem in
native vegetation on public land and the
limited resources available to deal with it, the
most efficient approach may be to operate on
a site by site basis, with sites of biological
significance given priority, so that the
management of a variety of weeds can be coordinated
with other efforts to maintain or
enhance the sites' biological values.
Some of the major environmental weed
species of native vegetation in the study area
are dealt with below, according to the
vegetation categories in which they
commonly occur. This is not a complete list.
Sub-alpine vegetation
The relatively low occurrence of weeds
refiects the environmental extremes here. A
prominent weed of sub-alpine woodland is
the English broom (Cytisus scoparius), which
appears to be proliferating unchecked,
especially on Mt Maflock.
Montane vegetation
English broom is also a problem species in
montane vegetation, as is blackberry (Rubus
fruticosus spp. agg.), which grows in dense
patches in saddles and gully-heads - for
example, around Royston River and Snobs
Creek.
Moist forests
Common moist forest weeds include Japanese
honeysuckle (Lonicera japonica), holly (Ilex
aquifolium), common ivy, cherty-plum
(Prunus cerasifera), sycamore maple (Acer
pseudoplatanus), poison-berries (CJestrwn
spp.), Himalayan honeysuckle (Leycesteria
formosa), holly, and blackberry. While not
particularly widespread, many of these
species become pests where private gardens
adjoin native forest, as in the Dandenong
Ranges. Also, while they may not grow in
dense stands, scattered oufliers can develop
into problem sites. The most widespread
weed species of moist forest are cat's ear
(Hypochoeris radicata) and spear thistle
(Cirsium vulgare), which usually occur as
background weeds.
Riparian foresi is among the most weedprone
of the vegetation communities.
Blackberry is the most obvious problem
species, but blue periwinkle, tutsan
(Hypericum androsaemum), Darwins
barberry (Berberis darwinii), wood-sorrels
{Oxalis spp.), and species of willow (Salix
spp.) may become established, particularly
where the riparian forest adjoins agricultural
land or townships.
Several grasses may also proliferate on moist
river flats: Yorkshire fog (Holcus lanatus),
cocksfoot (Dactylis glomerata), canarygrasses
(Phalaris spp.), and sweet vernalgrass
(Authoxauthwn odoratum).
Dry forests
The drier forests, particularly those with
relatively fertile soils, may contain a large
suite of introduced grasses and herbs, most of
which are intractable. One that may respond
to management is St John's wort (Hypericum
perforatum), a noxious weed that also infests
native vegetation, and that is especially
prominent in the EUdon district. Other
troublesome species, particularly around the
urban fringe of Melboume, are Monterey
pine, sweet pittospomm, and cotoneaster
(Conoteaster spp.).
Hair-grasses (Aira spp.), fescues (Vulpia
spp.), bromes (Bromus spp.), and quakinggrasses
(Briza spp.) are common weedy
grasses in dry forests. A number of herbs
such as cat's ear (Hypochoeris radicata),
species of centaury (Centaurium spp.), and
chickweeds (Cerastium spp.) also occur, but
usually as background weeils.
Two New South Wales species of Acacia,
cootamundra wattle (Acacia baileyana) and
early black wattle (A. decurrens), have
become naturalised and are also spreading in