Download TEN ACTION PLAN-2008-2012

TAROONA FORESHORE REHABILITATION SITE ACTION PLANS 2008-2012
PREPARED FOR TAROONA ENVIRONMENT NETWORK
BY NORTH BARKER ECOSYSTEM SERVICES
3.
MANAGEMENT ISSUES
3.1 A B O RI G I N A L H E R I T AG E
It is essential that vegetation management of the reserve does not conflict with the
recommendations given to protect Aboriginal heritage values. The Aboriginal Heritage Assessment
found that there are no significant sites remaining within the study area; the midden material
having been significantly degraded by urban development. The midden site at the Taroona High
School point (TASI 7729), just to the north of the study area, is of great significance as one of the
largest and least disturbed midden sites along the Derwent estuary.
The recommendations of the Aboriginal heritage assessment are for a precautionary approach to
future management practices. Any excavation works which reveal shell layers should cease
immediately and further advice from an Aboriginal Heritage Officer should be sought 1.
3.2 E N VI R O N M E N T AL W E E D S
Appendix 2 identifies all naturalised non-native species which includes all weed species. Short
summaries of the key species are given in Table 4.
A consequence of the disturbances associated with previous management and the proximity to
varied sources has been the proliferation of various environmental weeds within the study area. The
close proximity of environmental weeds in some neighbouring private gardens maintains an
ongoing source for future infestation.
Recent management activities have done much to reverse this trend by targeting the ‘worst
offenders’. It is important in weed management planning to recognise the futility of eliminating all
non-native species but instead to focus on key species that are having, or have the potential to have,
a negative impact upon the native flora but are also manageable.
There are intensive infestations of some herbs such as Kikuyu Pennisetum clandestinum, Panic
veldt grass Ehrharta erecta and oxeye daisy Leucanthemum vulgare for example that are only
effectively tackled by a committed and costly program that would require continuous follow up to
be effective in the long term.
It is important to acknowledge the ongoing exposure to outside sources of weeds and it is worth
considering the most significant of them for attention eg boneseed at Crayfish Point and Illawong
Reserve.
Abundant infestations of annual and herbaceous weeds exist along the main track of the foreshore.
Although it is a priority to treat declared and woody weeds initially, annual and herbaceous weeds
are continuously being spread along the pathway and pose a threat to the core areas of remnant
vegetation. It is worth attempting to contain the annual and herbaceous weeds within certain areas
of the reserve and aim to eradicate them from bushland in Taroona Park, Illawong Reserve and the
remnant vegetation from the sewage treatment plant to the planting area below TAFI. This may
involve spraying the track edges to reduce the spread of seed and also to maintain the edges of the
remnant bushland.
1
Stanton 2000
Table 4: Notable environmental weeds
SPECIES
STAT
US 6
OCCURRENCE
Boneseed
D
Widespread and occasional.
Bird spread. Proliferates after fire from long-lived woody seed in soil. Has been significantly
reduced through cut and paste and hand pulling. Will require annual monitoring during spring
flowering. Significant infestations found below bowling green and within Illawong Reserve.
Blackberry
D
Widespread and occasional.
Bird spread. Potential to infest drainage lines. Control by hand removal, cut and poison or
spraying of larger infestations.
Rubus fruticosus
WONS
Large leaf cotoneaster
-
Widespread. Most abundant along the
boundaries of residential properties.
Bird spread. Widespread source from neighbouring gardens. Minimal control efforts for this
species – often located within private areas.
Chrysanthemoides
monilifera
Cotoneaster
glaucophyllus
Fennel
MANAGEMENT
Cut and poison with woody herbicide.
D
Widespread with patchy infestations
along the foreshore, including planting
areas and extensive infestations
below sewage treatment works in
land slide area.
Small seed spread by animals and machinery. Generally proliferates in disturbed areas but
limited spread into intact native vegetation. Best controlled by herbicidal spraying.
-
Occasional with infestation east of
Kelvedon Oval.
Vigorously smothers other vegetation. Wind disperses seed. Best control is to cut climbing
stems when in the canopy and leave aerial plant parts to dry out, dig out small roots and
stems and re-spray the regrowth.
-
Several patches below residential
properties. Found within planting
areas along foreshore and below
Seaview Avenue properties.
Spread from illicit garden dumping and in contaminated soil. Infestations smother all other
ground covers. Difficult to eliminate. Requires timely use of herbicide cocktail.
-
Occasional with several patches
along the foreshore at Illawong
Reserve, Niree Parade and Crayfish
Point.
Controlled by herbicidal spraying.
-
Occasional.
Bird spread. Difficult to eliminate. Requires timely use of appropriate woody herbicide –
spraying or cut/paste.
African boxthorn
D
Occasional behind boatsheds and
waterfront.
Bird spread. Difficult plant to tackle with its large spines. Best controlled at this site through
cut and paint with woody herbicide.
Lycium ferocissimum
WONS
Mirror bush
-
Widespread and occasional along the
foreshore and along residential
properties.
Bird spread. Hand pull small plants; cut and paint larger ones
-
Several mature trees on foreshore
reserve resulting in localised
establishment of wildlings.
Investigate gradual replacement of mature trees with native plants. Hand pull wildlings.
Widespread and occasional. Very
bad infestation in Passionfruit Gully
and occasional along waterfront.
Spread by birds and animals. Smothers or collapses other vegetation. Remove all fruit and
either dig out or cut and paint stems, ensuring all stems are treated
Occasional within small infestations
along edges of Taroona Park.
Seeds are long lived, spread by water, vehicles, in contaminated soil and dumped garden
waste. The seed pods are explosive and can spread up to 3 metres from the parent plant.
Methods of control for canary broom include slashing, hand pulling, and chemical control.
Foeniculum vulgare
Cape ivy
Delairea odorata
Blue periwinkle
Vinca major
Red valerian
Centranthus ruber
Briar rose
Rosa rubiginosa
Coprosma repens
Radiata pine
Pinus radiata
Banana passionfruit
Passiflora sp.
Montpellier broom
Genista monspessulana
D
– ‘D’ – declared weed –Tasmanian Weed Management Act, WONS - Weed of national
significance
6
Declared weeds are listed under the Tasmanian Weed Management Act 1999. Each of these has a
statutory weed management plan which includes requirements for control or eradication which is
characterised by municipality. Declared weeds include environmental as well as agricultural and
silvicultural weeds. Environmental weeds are species which readily naturalise into native vegetation
thus presenting a management hazard to the maintenance of natural areas.
Weeds of National Significance (WONS) include 20 key species across Australia. These are
identified as ones for which financial assistance for management is linked to strategic regional
programmes administered by the Commonwealth.
3.3 T RE E D E CL I N E
There have been notable deaths of various tree and shrub species in recent years. These have been
scattered along the foreshore. Most deaths are of drooping sheoak Allocasuarina verticillata, and
native hop Dodonaea viscosa, below the track in zone 7. These cannot be attributed to disease.
Most plants are mature specimens. The most likely cause is from drought stress which has impacted
on mature and over mature plants. The age structure of the vegetation is such that these plants have
reached late maturity. Death is inevitable and natural. However in a small area when it occurs in
such a widespread manner it is visually confronting. Although at the landscape level it is preferable
to allow for dead shrubs to remain in situ as habitat, where the visual impact is greatest, or there are
safety concerns, there may be a case for their removal. There is also a fire hazard associated with a
mass of dead twigs and branches close to walking tracks. There may be incidences where active
planting could supplement this process following the removal of larger dead trees.
3.4 P L AN TE D T RE E S
There is evidence of planting of both exotic and native Tasmanian trees within the foreshore
reserve. Non-native trees include radiata pine Pinus radiata, macrocarpa Cupressus macrocarpa
and Norfolk Island pine Araucaria excelsa. Some inappropriate natives have also been planted
within the foreshore area. The ecological impact of such introductions needs to be taken into
consideration. It is important to note that the bushland is far from pristine and has been significantly
altered by management practices. Therefore it is recommended that where the exotic species is
having a negative impact on bushland values, its removal is recommended. In other instances, the
parent plants could be retained and monitored.
Several planted trees and shrubs are now spreading or have the potential to spread through seedling
establishment in Zone 8 (as shown on the weed map). These include non Tasmanian species such
as mainland species of eucalypt Eucalyptus sp., Melaleuca armillaris, Melaleuca nesophila, Acacia
saliciformis and Acacia pycnantha at Belhaven Reserve. Several mature Pinus radiata are also
found within the study area sporting occasional seedlings beneath their canopy.
3.5 F I RE M A N AG E M E N T
The native vegetation is adapted to fire. Some plant species and forest types require fire for their
maintenance and to trigger regeneration. The fire ecology of dry sclerophyll forest which
characterises the area is such that it is typically maintained through a fire frequency between 10 and
25 year intervals. Biodiversity is maximised by having a range of fire histories at the landscape
level. Where small pocket remnants of vegetation occur fire is considered less relevant as a
management tool. In the urban situation burning is controversial and is also hazardous where there
is a large number of assets. Fire management planning for small urban bushland reserves is more
about protecting these assets through adequate firebreaks and suitable access for fire fighting
purposes.
There have been no substantial fires since 1967 when all bushland areas are understood to have
been affected by the Tasmanian ‘black Tuesday’ wildfire. A significant fire in 1998 which burnt
large areas of forest above Taroona and Albion Heights extended into the gully near the southern
boundary of Illawong Reserve.
Biomass reduction can be achieved by means other than fire.
Recruitment of fire dependent species can be artificially achieved through active planting.
Fire risks killing newly planted trees and shrubs and reducing young forest cohorts. The eucalypts
present within the study area can regenerate in the absence of fire.
The largest forest remnants at Illawong Reserve and Taroona Park may be considered suitable
candidates for active burning. Key determinants would be whether or not there is a lack of
regeneration, or over abundance of dead and rank understory species. There is little evidence of
either which cannot be more easily attended to through direct clearing and planting. Consequently
the use of fire as a management tool is not recommended.
3.6 T H R E AT E N E D S P E C I E S H A BI TA T
3.6.1 Swift Parrot Habitat
The blue gums in the area are known to be utilized for their foraging resource by swift parrots
Lathamus discolor. Blue gum is the prime foraging tree for the swift parrot Black gums provide
secondary foraging resource which is understood to be significant in years where blue gums fail to
flower or in the early spring prior to blue gums coming in to flower.
Swift parrots are protected under both Tasmanian and Federal threatened species legislation and
categorized as endangered with an estimated breeding population of less than 1000 pairs2.
There are mature blue gums throughout the entire study area at Taroona. TEN has been planting
replacement blue gums and black gums where possible to ensure a continuous supply of adequate
food for swift parrots. The study area between Taroona Park and Illawong Reserve is well catered
for with a mix of large scattered blue gums along the foreshore between these two areas, with
adequate numbers of regenerating saplings.
Planting of blue gums and black gums in other areas should occur where possible to maintain food
source. It is important that the planting of such large gums are well planned, so as not to interfere
with services, established lookouts or nearby residential properties.
Birds utilise direct routes to fly between prime foraging trees. Although they will generally fly high
above the houses there are situations where their flight path leads them below the canopy. Certain
structures that these fast flying birds fail to notice include chain link fences and expansive glass
windows (especially where they are see-through, such as on corners of buildings, or are reflective of
trees or sky). These structures represent the greatest hazard for collision which is a significant factor
in mortality rates of swift parrots.
3.6.2 Eastern-barred Bandicoot
The eastern–barred bandicoot Perameles gunnii, a small pale tan marsupial with dark dorsal stripes,
inhabits grassland and grassy woodland, bushland/pasture interfaces and larger suburban gardens.
Bandicoots forage in open grassy areas but for shelter and nesting they require a dense ground cover
of native tussock grasses, sedges, shrubs and even garden plantings. They forage after dusk and
2
Swift Parrot Recovery Team (2001)
seek shelter during the day in grass-lined nests where the cover is thick.
This species is not listed under Tasmanian threatened species legislation. The national listing,
however, classifies it as endangered on the mainland and vulnerable in Tasmania. It is widespread
across Tasmania, particularly in the eastern and northern lowland regions. Although subject to
predation from domestic pets (cats and dogs) it persists in many peri-urban situations. It is perhaps
most at risk from the potential expansion of the European fox in Tasmania.
Avoidance of an over tidy approach to bushland management is important to ensure suitable shelter
is maintained. This includes the retention of dense thickets and gradual, phased replacement of
weedy herbage which may be providing the only local habitat. Revegetation planning should
include provision of adequate ground cover species for habitat purposes.
3.7 R E V EG E T AT I O N
In areas where native vegetation exists, natural regeneration can occur with appropriate
management. Furthermore plant establishment and survival is usually much greater with naturally
seeded plants. Within the study area, there are some instances where replanting is required to
support natural regeneration:
1. To enhance the range of species and supplement some of the less common species.
2. To replace weeds in specific sites.
3. To establish new plantings in areas currently managed as grass.
3.8 W AT E R
RUNOFF
At numerous sites along the foreshore there are drainage areas flowing into the River Derwent.
These areas are often associated with erosion and weed outbreaks. Some areas remain permanently
damp. Stormwater management is beyond the scope of any bushcare group, however it is
recommended that such areas are targeted for weed control.
3.9 A D J AC E N T L A N D I M P A CT S
The best endeavours for controlling weeds within the reserve can be partially undone if sources
outside the site remain unmanaged. There are many adjacent properties which have a bearing on
this.
Illawong Reserve, for example, has some dense infestations of broom which are spreading from
adjacent private properties and from upper areas of the drainage line. In order to control the weed,
work will require a combined approach with TEN and the private land owners. This will require
liaison with the properties in upper areas of the drainage line and with those properties directly
backing onto the reserve.
‘Passionfruit Gully’ is an area of private land adjoining the coastal foreshore, so named by TEN for
the proliferation of banana passionfruit vines. Some of the gully owners support conservation and
restoration works of the gully habitat. Work within this area has been undertaken in the lower areas
above Hinsby Beach. In order for work to be successful the weed issues in the upper areas of the
gully will need to be addressed. Some work is already being undertaken by a local resident which
has been extremely successful, however above these areas there are major problems with banana
passionfruit and cape ivy which will require work in the future. For control of these weeds to be
successful liaison with the adjacent land owners will be required.