Factors Affecting Flora Conservation - Victorian Environmental ...

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which normally would be confined to coastal
dune scmb, but frequently extends into
adjoining vegetation and bluebell creeper
(Sollya heterophylla) which is a pest in the
Arthurs Seat area.
Cinnamon fungus
Pathogens
Although present in the study area, cinnamon
fungus (Phytophthora cinnamomi) has yet to
display the impact on native vegetation that
has occurred in the Brisbane Ranges, Otway
Ranges, Wilsons Promontory, and Gippsland.
Species characteristic of heathland or heathy
woodland vegetation appear to be most
susceptible to the fungus, with members of
die Proteaceae (hakeas, banksias, grevilleas)
and grass-trees (Xanthorrhoea spp.) being
most noticeably affected. A range of
vegetation communities within the study area
are potentially susceptible, but the extent of
any current infection is unknown.
Myrtle wilt
This disease affects myrtle beech. First
documented in 1973, and known to occur in
Tasmania and southern Victoria, it is
associated with infection by a native fungus,
Chalara australis. The result of infection is
wilting and leaf-fall, beginning with the
crown. Mature trees appear to be most
susceptible. Most infected trees die, usually
12 to 30 months after the appearance of early
symptoms. Small, isolated stands appear
most vulnerable.
A correlation between the occurrence of
myrtle wUt and disturbance from timberharvesting
and roading has been documented,
and it would appear that these activities may
accelerate the spread of Chalara australis.
However, undisturbed stands may also be
affected.
The presence and extent of myrtle wilt in the
study area, and the threat it poses to cool
temperate rainforest, have not been studied,
but a suspected case has been reported from
Tyers River.
Pest Animals
The impact of grazing by rabbits on native
vegetation has not been studied in detail, but
is considered to be high. It is most
noticeable in plains vegetation and dry
forests. Indirect impacts may also occur
through the spread of weeds, and through soil
degradation associated with warrens.
Foxes act as a wide-ranging dispersal agent
for blackberry, particularly where roads
provide ready access to unaffected areas.
Native birds and bees pollinate large numbers
of native plants. Introduced species of birds
and the introduced honey bee can displace
their native counterparts, which may affect
the composition of native vegetation.
Introduced birds can carry the seeds of
environmental weeds with fleshy fiiiit (such
as blackberry, hawthorn, and cherry laurel).
Timber-harvesting
Human Activities
This is widespread in the study area,
especially in moist forests. Its effects on
native vegetation are the subject of scientific
study and much community debate.
Principally, it maintains the harvested
vegetation in relatively early successional
stages, and results in substantial short-term
soil disturbance.
Such changes may have ramifications for the
harvested forests, and the adjacent
vegetation, with regard to tire, soil stmcture
and nutrient levels, water quality and yield,
exposure to wind, changes in micro-climate,
and the spread of pathogens and weeds.
Scientific studies into the impacts of timberharvesting
on vegetation have been
undertaken. The Department of Conservation
and Environment has an ongoing program of
research, the Silvicultural Systems Project, to
investigate these issues and recommend on
any necessary improvements. The Board of
Works has undertaken and reported on the
results of long-term catchment studies into
forest hydrology. Refer to Chapter 20 for
further (liscussion.
Road construction and maintenance
A network of roads, both public and
restricted, has been developed in areas
supporting native vegetation to provide
access for a variety of purposes, including
timber-harvesting, recreation, mining, fire