REVIEW OF THE STATUS OF RIPARIAN VEGETATION AND FLORA OF THE MARY
RIVER AND ASSOCIATED SYSTEMS
(Confidential Pre-publication Draft)
Report No. 02/11
July 2002
Prepared by Garry L. Werren
Australian Centre for Tropical Freshwater Research
James Cook University, Qld, 4811
Phone: (07) 4781 4262
Fax: (07) 4781 5589
Email: [email protected]
Review of the status of riparian vegetation and flora of the Mary River and associated systems.
ACTFR Report No.02/11
TABLE OF CONTENTS
ACKNOWLEDGMENTS.....................................................................................................................II
1.
INTRODUCTION. .........................................................................................................................3
2.
BACKGROUND.............................................................................................................................3
3.
STUDY AREA. ...............................................................................................................................3
3.1.
3.2.
3.3.
3.4.
4.
FEATURES AT RISK....................................................................................................................8
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.
5.
CLIMATE. ............................................................................................................................5
LITHOLOGY, TERRAIN AND SOILS. ..............................................................................5
VEGETATION. ....................................................................................................................6
RIPARIAN FLORA. .............................................................................................................7
THREATENED REGIONAL ECOSYSTEMS..................................................................................8
RARE/THREATENED FLORA..................................................................................................13
BIODIVERSITY HOT-SPOTS/SIGNIFICANT AREAS ..................................................................19
WETLANDS...........................................................................................................................20
LANDSCAPE CONNECTIVITY .................................................................................................21
SYSTEM INTEGRITY AND THE SPREAD OF EXOTICS AND PEST SPECIES. ...............................22
CONDITION OF THE RIPARIAN VEGETATION................................................................23
5.1.
METHODS.............................................................................................................................24
5.2.
CONSIDERATION OF EXISTING CONDITION...........................................................................25
5.2.1.
Impact of factors unrelated to water resource development...........................................25
5.2.2.
Impact of factors associated with water resource development. ....................................33
6.
NEED FOR FURTHER RESEARCH AND MONITORING. .................................................35
6.1.
6.2.
7.
RESEARCH NEEDS. ...............................................................................................................35
MONITORING REQUIREMENTS..............................................................................................36
SUMMARY AND CONCLUSIONS. ..........................................................................................36
REFERENCES. ....................................................................................................................................39
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ACKNOWLEDGMENTS.
The author is particularly grateful for the assistance provided by many individuals, and in
particular by Brad Wedlock of the Mary River Catchment Coordinating Committee
(MRCCC), Scott Buchanan (DNR&M – Gympie), Denise Johnson (DNR&M (SoR) –
Brisbane) and Bill MacFarlane (EPA – Brisbane). I would also like to thank all other TAP
members for the great measure of professionalism they bring to this worthwhile
multidisciplinary exercise.
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1.
INTRODUCTION.
The Queensland Government, through the Resource Management Program of the Department
of Natural Resources and Mines (DNR&M), is implementing the Water Resource Planning
(WRP) process in a number of Queensland river basins. The first step in the development of a
WRP is to assess the current condition. The primary purpose of this report is to determine the
current condition of riparian vegetation associated with the rivers and streams in the Mary
WRP study area. This area includes the Mary River itself and the catchments of the Burrum
River and Beelbi Creek that adjoin the Mary Basin coastward of its middle reaches (Figure 1).
While the WRP covers all rivers and streams within the study area, this report focuses on
vegetation fringing major trunk streams and issues related to this stream component.
A secondary but nonetheless important function of this report is to present considerations
regarding the conservation status of vegetation communities (regional ecosystems) and their
constituent flora and fauna habitat values. This is required since these may be influenced by
water resource developments and warrant consideration in this planning exercise.
2.
BACKGROUND.
Environmental values and significance, including conservation values associated with the
riparian systems, were taken into account where applicable in the assessments. Information
was obtained initially from a review of existing reports and by interrogating State databases
such as HERBRECS (EPA 2001). These data were complemented by aerial photographic
interpretation of the most recent runs and by limited visits to 60 sites during May 2001.
The riparian vegetation was documented at each site visited using a rapid assessment protocol
derived from several systems (see Werren 2000), in particular, that approach employed during
the Snowy Water Inquiry (Young et al. 1998).
3.
STUDY AREA.
The study area (Figure 1) comprises the entire Mary River Catchment of approximately 9 700
km2 (Johnson 1997:2) and those of the neighbouring Burrum River and Beelbi Creek. It lies
wholly within the Southeast Queensland bioregion (Young and Dillewaard 1999) and mainly
straddles three of its constituent provinces (i.e. Gympie Block, Burnett-Curtis Coastal
Lowlands and Great Sandy), with minor representation of a fourth (i.e. Province 4 – Southern
Coastal Lowlands) in the extreme eastern lobe about Mt Cooroy, and a fifth (Province 3 –
Southeast Hills and Ranges) in the extreme south where the river rises at an elevation of
approximately 500 m. From those headwaters in the Conondale Ranges (Maleny Plateau)
some 80 km north of Brisbane, the Mary River flows a total distance of 307 km northward
through Gympie and then deflects north-eastwards through Maryborough to debouche into the
Great Sandy Strait west of Fraser Island (Pollard 2002:4).
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Figure 1. Mary Catchment WRP study area, showing basic reach subdivision (Note: the
catchment boundaries of the Burrum and Beelbi systems, to the immediate north, have
not been delineated)
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The Mary River is a perennial stream, with very few cease to flow periods on record, and a
mean annual discharge (at end-of-system) of 2 580 000 ML (Pointon and Collins 2000:26).
Discharge is variable, however, ranging from 122 000 to 4 665 000 MLyr-1 recorded at the
Miva gauging station (DPI 1995 cited by Stockwell 1997:28). The local relief of the
catchment is approximately 500 m, with the headwater streams exhibiting gradients of 6%
within the first 5 km (to upstream of Conondale), thereafter to Conondale the gradient lessens
to 0.62%, gradually reducing to 0.17% between Conondale to Kenilworth and 0.04% between
Kenilworth and the Tiaro tidal barrage (Stockwell 2001:28).
Water resource developments in the Mary catchment have resulted in the installation of 11 instream impoundments. These comprise two barrages (Mary River and Tinana Creek
barrages), five weirs (at Maleny, Imbil, Goomeri, Tallegalla and Teddington) and four dams
(Baroon Pocket, Six Mile Creek/Lake MacDonald, Borumba and Cedar Pocket dams)
(Stockwell 2001:40). Additional impoundments (e.g. Lenthall’s Dam) have been constructed
in the Burrum and weirs in the Beelbi Creek system.
The regional centre of Gympie, with a population of approximately 33 000 (Pointon and
Collins 2000:19) is located centrally within a catchment that extends from the southern ranges
about Maleny northward to Maryborough (with a comparable population to that of Gympie)
and Burrum Heads, west of Fraser Island. The area has been subjected to disruptions
associated with intensive agricultural and forestry activities for over a century (Wells et al.
1984) and, more recently, extensive residential development, particularly about the middle to
lower reaches.
3.1.
Climate.
This catchment is predominantly sub-tropical – i.e. moist sub-tropical in the south about the
coastal ranges and dry sub-tropical on the western ranges (Pollard 2002:4). It receives an
annual rainfall of between >2 000mm about the ranges near Maleny in the extreme south-east
to <800mm in the north-western Munna Creek sub-catchment about Brooweena (Johnson
1997:2), most of which falls in the summer months (i.e. December-March). At Gympie mean
monthly maximum temperatures range from the low 20s to low 30s while minima range from
between 20oC to 5oC (Pointon and Collins 2000:5). Severe frosts can be expected along the
valley floors and lowlands (Stockwell 2001:27).
3.2.
Lithology, Terrain and Soils.
Stockwell (2001:29) points out that “the river’s course reflects the north-south trend of the
regional geology”. Upstream of Gympie, the area is underlain chiefly by Palaeozoic
sedimentary and volcanic rocks of the Carboniferous-Permian Amamoor and Permian
Gympie groups (Pointon and Collins 2000:30) into which streams are deeply incised. In the
central section, downstream of Gympie, the river cuts a deep gorge through the resistant
Myrtle Creek Sandstone formation before traversing granitic rocks of the Station Creek
Adamellite and thereafter following a sinuous course within a broad floodplain through the
softer sedimentaries of the Tiaro Coal Measures (Stockwell 2001:29). Escarpment retreat has
been accompanied by the deposition of unconsolidated colluvia along footslope benches that
are sensitive to landslip. This has implications for fluvial sediment transport.
The south and south-western sections of the catchment are situated in the Gympie Block
(Province 7 of the Southeast Queensland bioregion). The physiography consists of low hills
and alluvial valleys on old sedimentary rocks, metamorphics and intermediate to basic
volcanics with scattered acid volcanic intrusions (Young and Dillewaard 1999:12/6). In
contrast, the northern part of the catchment is situated on the southern end of the broad coastal
plain of the Burnett-Curtis Coastal Lowlands (Province 8). This consists of sedimentary rocks
of the Maryborough Basin and marine and alluvial deposits. Igneous rocks occur near Mount
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Bauple. The south-eastern margin of the catchment is situated in the Great Sandy Province
(Province 9), with the exception of the area about Mt Cooroy which extends into the Southern
Coastal Lowlands (Province 4) (Young and Dillewaard 1999:12/75). This area is underlain by
sand masses, sandstone hills of generally low relief and alluvial areas with remnant
vegetation. Some areas of extensively eroded and deeply weathered land surfaces with laterite
profiles are present on remnant Tertiary surfaces. This part of the catchment, along with the
southern hills and ranges about Conondale and Maleny, experiences comparatively high
rainfall, but it is also generally the most infertile, with strongly leached sandy podsol soils
predominating. Vegetated areas here have been severely reduced by clearing for plantation
forestry, including exotic slash pine (Pinus elliottii) plantations (van Kampen and Wedlock
2002:19).
Three broad ‘soil landscapes’ are described for the Mary WRP study area (Pointon and
Collins 2000:32). The corridor of the major trunk stream is flanked by soils with gradational
profiles ranging from yellow-red acid friable earths of the upper catchment, through to neutral
and alkaline dark friable earths along the middle reaches to yellow and leached yellow-grey
acid earths (with subsurface mottling) of the lower reaches. The interfluves are characterised
by interdigitated lenses of uniform texture profile soils (ranging from leached sands to friable
loams) and texture-contrast or duplex soils with sandy to hard setting loamy upper horizons
overlying clayey, often pedal, subsoils (Pointon and Collins 2000:32). Pyretic sediments or
potential acid sulphate soils (PASS) are associated with mangroves and samphire flats of the
coastal fringe.
3.3.
Vegetation.
The natural vegetation of the upper (southern) section of the catchment is characterised by a
suite of tall open eucalypt forests with significant admixtures, expanses and/or enclaves of
rainforest that is predominantly araucarian notophyll vine forest using the terminology of
Webb and Tracey (1981). Natural vegetation cover of the central and central western
sections is typically open forest and woodland with some dry rainforest (araucarian semideciduous microphyll/notophyll vine forest/thicket) components. The northern and northeastern portions are characterised by low-medium open forest/woodland with a range of
canopy dominants including eucalypts and bloodwoods (species of Eucalyptus and Corymbia
respectively), paperbarks (Melaleuca spp.) and wattles (Acacia spp.), often with significant
heath-dominated subcanopies and/or ground layers (Queensland Herbarium, 1997 in Pointon
and Collins, 2000).
Vegetation integrates a wide range of environmental factors, not the least of which are
climate, topography and soils. In the wetter areas of the upper catchment and its eastern
fringe, vegetation ranges from closed forest (subtropical rainforest or vine forest), through tall
open (wet sclerophyll) forest to dry sclerophyll forest or woodland dominated by eucalypts,
wattles and paperbarks. On the nutrient poor sites (as well as in the drier west where eucalypts
and bloodwoods dominate) near the mouth of the Mary and Burrum rivers to the east and
north-east, stunted dry sclerophyll woodland is characteristic (O’Donnell 1997:8).
Within the Southeast Hills and Ranges province, eucalypt open forest and tall open forests
typically
characterised
by
flooded
gum
(E.
grandis)
and
blackbutt
(E. pilularis) predominate, along with complex notophyll vine forests comprising a mixture of
mesic species and auracarian notophyll vineforest with characteristic bunya pine or hoop pine
(Araucaria bidwillii and A. cunninghamii respectively) emergents (Young and Dillewaard,
1999). The Gympie Block is characterised by relatively fertile soils and possesses an original
vegetation cover typified by extensive areas of araucarian notophyll and microphyll vineforest
with or without sclerophyll emergents and/or co-dominants and mixed species medium-tall
eucalypt (especially flooded gum) and bloodwood (Corymbia spp.) open forest. In areas
receiving less than 1000 mm annual rainfall, forests dominated by ironbarks (E. crebra, E.
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fibrosa, E. sideroxylon) replace the mixed species sclerophyll forests (Young and Dillewaard,
1999). In contrast, the Burnett-Curtis Coastal Lowlands supports vegetation communities that
comprise heathlands (mostly with Banksia spp.), paperbark (M. quinquenervia) open forests
and eucalypt (often dominated by Spotted Gum, E. maculata) open forests and woodlands
(Young and Dillewaard, 1999). The moister Great Sandy province is typified by notophyll
vineforests, brush box (Lophostemon confertus) and turpentine (Syncarpia hillii) tall open
forest, mixed eucalypt open forests, banksia woodlands and paperbark (M. quinquenervia)
dominated woodlands (Young and Dillewaard, 1999). Low mangrove forests/thickets line the
intertidal reaches of the Mary and Burrum rivers and other streams of the study area.
Several rainforest types occur within the catchment. These comprise a range of subtropical
notophyll and mesophyll vine forests varying in structural complexity, including araucarian
notophyll vine forest with both bunya and hoop pine. Dry rainforest patches, often with hoop
pine emergents (i.e. araucarian microphyll-notophyll vine forest and semi-evergreen vine
thicket), are located on more fertile, fire-proof sites in the western and north-western section
of the catchment about Brooweena and also along the eastern watershed about Mt Bauple and
Mt Pinbarren near Cooran and in the south-central portion about Imbil (O’Donnell 1997:2737). Rainforests are generally floristically rich with a variety of tree species represented.
Moist tall open forest or wet sclerophyll communities dominated by flooded gum, brush box
and common turpentine (S. glomulifera) are best developed in the Pomona-Cooroy area west
of Tewantin (O’Donnell 1997:40). These communities consist of a mesic forest sub-canopy
with the sclerophylls as emergents. Similar forest types that also feature blackbutt occur in
the south-eastern portion of the catchment drained by Obi Obi Creek, and in particular, about
Baroon Pocket Dam.
As for most catchments, dry sclerophyll communities that vary structurally from medium
open forest to low grassy open woodland are the most widespread vegetation types of the
Mary study area. These communities occupy the more nutrient-poor or rapidly draining (e.g.
sandy) soils of the wetter sections of the catchment and the drier areas throughout.
Characteristic dominants include spotted gum, Gympie messmate (E. cloeziana), lemonscented gum (C. citriodora), grey gum (E. propinqua) and narrow-leaved ironbark (E.
crebra), and along the eastern coastal ranges, pink bloodwood (C. intermedia). In the drier
north-eastern region, coast and black cypress pine (Callitris columellaris, C. endlicheri) are
distinctive dry sclerophyll open forest dominants (O’Donnell 1997:46). Forest red gum (E.
tereticornis) is characteristic of the lower slopes, flood-out areas, creek flats and within the
riparian zones of streams draining the drier sections of the catchment. Paperbarks are major
components of open woodland on poorly drained areas of the northern part of the area.
Catchment vegetation has been depleted by over 50% with an estimated 42% (Accad et. al.
2001 cited by van Kampen and Wedlock 2002:8) remaining in a comparatively intact state.
Very major changes to catchment vegetation have occurred since European settlement. Much
(i.e. up to 77 000ha – Buchanan, pers. comm.) has been replaced by plantation forestry, and in
particular, extensive plantations of native hoop pine and exotic slash pine (Pinus elliottii), and
other areas developed for agriculture and towns. In the case of the Mary River, virtually all of
the native vegetation has been removed from the river flats, with the remaining riparian
corridor now generally less than 20 m wide - the exception is a 3 ha remnant of dense vine
forest on private land south of Gympie (DPI 1995:5).
3.4.
Riparian flora.
Many species are prevalent along the streams of the catchment. The major riparian dominants
include three species of she-oak (Casuarina cunninghamiana, C. glauca and Allocasuarina
torulosa) and a hybrid between the former two (Wylie et al. 1993b:10). The weeping
bottlebrush (Callistemon viminalis) is amongst the most common of the rheophytes within the
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system. The paperbark M. bracteata is also moderately common. In many places, forest red
gum features prominently in the vegetation flanking stream channels.
The moister reaches are typically fringed by rainforest typified by a range of species. The
rheophytes of these communities include waterhousea (Waterhousea floribunda), water gum
(Tristaniopsis laurina) and creek cherry (Syzygium australe). Further from the watermark
species such as black bean (Castanospermum australe), figs (Ficus racemosa, F. coronata),
lillypilly (Acmena hemilampra) and native elm (Aphananthe philippinensis) are commonly
encountered. The gallery rainforest along Tinana Creek, in particular, is well developed and
of special conservation value (Van Kampen and Wedlock 2002).
Increasingly, these species are ceding to a host of alien invaders such as Chinese elm (Celtis
paniculata), camphor laurel (Cinnamomum camphora), lantana (Lantana camara) and privets
(Ligustrum sinense, L. lucidum) that are now dominating the community structure, along with
vines such as cat’s-claw creeper (Macfadyena unguis-cati) and madeira vine (Andrera
cordifolia). Infestations are particularly prevalent about the main channel downstream of
Conondale to the confluence of Little Yabba Creek, downstream of Kenilworth to a point east
of Imbil, along the Gympie reach from the Six Mile Creek confluence to about the Wide Bay
Creek junction and again downstream from above Tiaro to the Mary River barrage. They are
also conspicuous along tributary streams such as along Obi Obi Creek about Maleny, the
middle to lower reaches of Amamoor Creek and along similar reaches of Glastonbury Creek
(Pickersgill 1997).
Introduced pasture grasses legumes and shrubs/small trees such as leucaena (Leucaena
leucocephala) are similarly proliferating along the disturbed riparian verge of streams within
the drier parts of the catchment. These exotic species also feature in the more moist areas of
the catchment where the stream verge vegetation has been severely disrupted and/or cleared.
4.
FEATURES AT RISK.
Prior to detailed evaluation of the condition of riparian communities, it is pertinent to consider
elements within the catchment that by virtue of their location, functional or biodiversity
significance may be at risk from water resource and other developments. These features
include ecosystems that are considered to be of concern/endangered, similarly listed plant and
animal species, locations of strategic importance within the landscape due to their
biodiversity, habitat and/or linkage value and the integrity of systems that may be jeopardised
because changes can assist the invasion of exotic species.
4.1.
Threatened Regional Ecosystems.
More than 80 regional ecosystems (REs) have been described for the Mary River and
adjoining catchments (EPA 2001). As of March 2002, six of these were classified as
‘endangered’ under the Queensland Vegetation Management Act (1999) (EPA 2002). A
further 28 REs were classified as ‘of concern’ (Table 1). Of these, eight (comprising two
‘endangered’ and six ‘of concern’) REs are deemed to be associated with streams and
wetlands of the Mary WRP study area.
The ‘endangered’ regional ecosystem 12.3.1 (Gallery rainforest on alluvial plains) is the one
most clearly associated with streams of the catchment. This RE is also important as habitat for
flora and fauna species of particular conservation interest including southern penda
(Xanthostemon oppositifolius), Deep Creek fontainea (Fontainea rostrata), Richmond’s
birdwing butterfly (Ornithoptera richmondia) and Coxen’s fig parrot (Cyclopsitta
diophthalma coxeni) along with other fruit-eating birds (Young and Dillewaard 1999:12/15).
Main occurrences are in disjunct patches along Tinana Creek from Teddington southward to
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the junction with Coondoo Creek and south along Coondoo Creek (van Kampen and Wedlock
2002:25)
(Figure 2). This RE is best developed on silty alluvial deposits on the inside of stream
meanders that are largely protected from fire.
Riparian areas along Tinana Creek between Teddington Water Reserve and the Coondoo
Creek junction generally host a mix of riparian and rainforest species dominated by
waterhousea, black bean and coastal she oak. The number of rainforest species present is
variable with only a few locations so far found with a well-developed gallery rainforest
ecosystem. Van Kampen and Wedlock (2002:23) indicate that the best examples of RE 12.3.1
are at Teddington Weir and at Magnolia, north- west of Golden Gate Bridge. Both sites
support rainforest ecosystems with emergent hoop pine and kauri pine (Agathis robusta) as
well as a number of endangered, vulnerable and rare/restricted plant species.
Another ‘endangered’ RE is 12.3.3 - Eucalyptus tereticornis tall open forest on alluvial plains
and associated lower slopes. Within the study area it appears to be restricted to about Kilkivan
along Wide Bay Creek and its tributaries and again along the middle reaches of Doogul Creek
in the Burrum River catchment. The linear configuration of the mapped units of this
vegetation type (DNR&M 2002 after EPA 2001; information courtesy of Neihus, pers.
comm.) clearly demonstrates its close association with streams. Owing to its highly residual
nature, very limited representation within the protected area network, the degree of
disturbance evident within the small areas that do remain (Young and Dillewaard
1999:12/16), it is of importance to ensure that water resource development does not contribute
to endangering processes for this RE.
The highly degraded condition of much of the she oak-dominated riparian zone of the Mary
River may suggest that this linear forest type constitutes a hitherto undocumented RE akin to
one described for the wet tropics region (i.e. 7.3.26 – Goosem et al. 1999) that might also be
listed as ‘endangered’.
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Table 1. Rare/Threatened Regional Ecosystems of the Mary WRP Study Area (after
EPA 2001; see also Young & Dillewaard, 1999; conservation status Version 2.1 as of
March 2002 – www.env.qld.gov.au/environment/science/wildlife/sbe.html )
RE No.
Description
Status 1
12.2.2
Mixed microphyll/notophyll vineforest on beach ridges
Endanger
ed
12.2.5
Corymbia spp., Banksia integrifolia, Callitris columellaris, Acacia spp.
open forest to low closed forest on beach ridges
Of
concern
12.2.7
Melaleuca quinquenervia or M. viridiflora open forest/woodland on sand Of
plains
concern
12.3.1
Gallery Rainforest (notophyll vineforest) on alluvial plains
Endanger
ed
12.3.3
Eucalyptus tereticornis tall open forest on alluvial plains & associated
lower slopes
Endanger
ed
12.3.5
Melaleuca quinquenervia tall open forest near coastal alluvial plains
Of
concern
12.3.8
Swamps with Cyperus spp., Schoenoplectus spp., Eleocharis spp.
Of
concern
12.3.11
Eucalyptus siderophloia, E. tereticornis, Corymbia intermedia open
forest alluvial plains
Of
concern
12.3.12
E. umbra or E. exserta, M.viridiflora on alluvial plains
Of
concern
12.3.13
Closed heathland on seasonally waterlogged alluvial plains near coast
Of
concern
12.3.14
B. aemula woodlands on alluvial plains near coast
Of
concern
12.5.3
E.tindaliae ± E. racemosa open forest on remnant Tertiary surfaces with
deep red soils
Endanger
ed
12.5.8
E. hallii woodland on complex of remnant Tertiary surfaces &
sedimentary rocks
Of
concern
12.5.9
Sedgeland/herbland in low-lying areas on remnant Tertiary complexes
(as above)
Of
concern
12.8.8
E. saligna or E. grandis tall open forest on Cainozoic igneous rocks
Of
concern
12.8.20
Shrubby woodland with E. racemosa or E. dura on Cainozoic igneous
rocks
Of
concern
12.9/10.1
Tall mixed open forest on coastal sedimentaries
Of
concern
12.9/10.3
E. moluccana open forest on sedimentaries
Of
concern
1
The conservation status (ConStat) categories applying to regional ecosystems are broadly comparable to those erected
for species whereby ‘endangered’ refers to a type that has been reduced to <10% its former extent and ‘of concern’ (=
‘vulnerable’) indicates an ecosystem type that has been reduced to between 10-30% its pre-European extent (Sattler 1999:1/11).
Ascription to these categories is also likely indicative of the ongoing nature of threatening processes. Those REs associated with
streams or wetlands are indicated as shaded entries.
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RE No.
Description
Status 1
12.9/10.10
M. nodosa low open forest on sedimentaries
Of
concern
12.9/10.16
Araucarian microphyll/notophyll vine forest on sedimentaries
Endanger
ed
12.9/10.20
E. montivaga open forest on sedimentaries.
Of
concern
12.11.9
E. tereticornis, C. intermedia higher altitude open forests on
metamorphics ± volcanics
Of
concern
12.11.11
Araucarian microphyll vineforest on metamorphics ± interbedded
volcanics
Of
concern
12.11.14
E. crebra, E. tereticornis woodland on metamorphics ± interbedded
volcanics
Of
concern
12.11.16
Mixed tall open forest with E. cloeziana on metamorphics ± interbedded
volcanics
Endanger
ed
12.12.1
Simple notophyll vine forest usually with abundant Archontophoenix
cunninghamii on Mesozoic to Proterozoic igneous rocks
Of
concern
12.12.8
E. melanophloia woodland on Mesozoic to Proterozoic igneous rocks
Of
concern
12.12.9
Shrubby woodland with E. dura on peaks of Mesozoic to Proterozoic
igneous rocks
Of
concern
12.12.10
Shrubland of rocky peaks on Mesozoic to Proterozoic igneous rocks
Of
concern
12.12.12
E. tereticornis, E. crebra,or E. siderophloia, L. suaveolens open forest
on granite
Of
concern
12.12.14
Mixed shrubby woodland of near coastal areas on Mesozoic/Proterozoic
igneous rocks
Of
concern
12.12.24
Angophora leiocarpa, E. crebra woodland on Mesozoic/Proterozoic
igneous rocks
Of
concern
12.12.25
E. fibrosa fibrosa tall woodland/open forest on Mesozoic/Proterozoic
igneous rocks
Of
concern
12.12.28
E. moluccana tall open forest on Mesozoic to Proterozoic igneous rocks
Of
concern
Australian Centre for Tropical Freshwater Research
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ACTFR Report No.02/11
Kilometres
Figure 2. The occurrence of one of the foremost of the ‘endangered’ REs of the study
area, gallery rainforest, in its stronghold within the Tinana Creek sub-catchment (after
van Kampen and Wedlock 2002:26 - Figure 15, drawn from the work of the Queensland
Herbarium’ vegetation mapping project) demonstrating (by definition) its close
association with the stream.
Australian Centre for Tropical Freshwater Research
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Of the six REs associated with waterways and waterbodies of the study area that are accorded
‘of concern’ status, 12.11.1 (i.e. simple notophyll vine forest usually with abundant
Archontophoenix cunninghamii on Mesozoic to Proterozoic igneous rocks) or “gully vine
forest” (EPA 2002:9) is another riparian community that is vulnerable to water resource
development. This type occurs in small swarms or clusters of small patches in the upper
catchment along Obi Obi Creek downstream of Baroon Pocket Dam, and presumably
elsewhere about headwater streams in that part of the catchment but are so spatially restricted
that they are not recorded at a mappable scale. The remaining types are less connected with
streams but are with lentic wetlands. These include those of more permanent features (i.e.
12.3.8), seasonally waterlogged sites (12.3.13 and 12.5.9) and of flood-out or receiving areas
(12.3.5 and 12.3.11). Study area occurrences are not readily apparent on existing vegetation
maps.
4.2.
Rare/Threatened Flora.
Detailed information obtained from interrogating the HERBRECS database of the Queensland
Herbarium (EPA 2001), provides details of that subset of rare and/or threatened taxa likely to
be associated with riparian/wetland systems of the study area. Those listed species that may
be impacted by flow regulation are set out in Table 2.
Some 55 plant taxa comprising nine endangered species, 22 vulnerable species and 24 others
listed as rare/restricted are recorded from, or considered likely to occur in, the Mary
Catchment and neighbouring catchments of the Burrum River and Beelbi Creek (Table 2). It
is evident that both water resource development (particularly that associated with the flooding
of riparian systems upstream of major impoundments on the Mary) and external factors such
as extensive clearing for agriculture have already impacted on species. Two-thirds of these are
known to occur within or can be considered likely to be associated with streams and wetlands
of the study area. This is particularly so in the case of listed species – e.g. X. oppositifolius occurring within the gallery rainforest (12.3.1) discussed above and in RE12.9/10.16. It is
noted that several other rare/threatened species do occur within the study area but are not
associated with streams/wetlands and, therefore, not considered to be threatened by in- or
near-stream activities. It can be argued with some force, however, that water resource
developments that are linked with activities that involve adverse land use impacts within a
catchment can constitute threatening processes for such species.
Since many of the species listed in Table 2 are representative of mesic (moisture-dependent or
broadly ‘rainforest’) taxa they will occur about the wetlines and/or waterbodies within the
wider landscape. The endangered mintbush, Plectranthus torrenticola, by virtue of its
specific epithet (i.e. reflecting its tolerance of fast-flows or ‘torrents’), is clearly associated
with streams, but there is insufficient locational information available to precisely determine
just how susceptible this may be to existing or potential water resource developments,
including flow regime changes, apart from noting its recorded occurrence along reach M4 of
the Mary River downstream of Kenilworth. The rare/restricted paperbark, Melaleuca cheeli is
a plant of seasonal wetlands in the vicinity of Dundowran about Beelbi Creek (McDonald,
pers. comm.). It is known that Acacia perangusta of the adjacent Beelbi Creek catchment
(included within the Mary WRP study area because water is extracted from this and the
Burrum to supply Hervey Bay City) favours disturbance and may well feature in riparian
systems that are dynamic due to flood disturbance. Wedlock (pers. comm.) reports an
additional newly described or recorded species Clausena smyrelliana (Rutaceae) where
neither details of its conservation status or location within the landscape are currently
available.
Australian Centre for Tropical Freshwater Research
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ACTFR Report No.02/11
Table 2: Rare/threatened plant species of the Mary River WRP study area. (Source:
HERBRECS database 2001; with additional records (§) of van Kampen & Wedlock
2002)
A. Species that are recorded in, or considered likely to occur within, riparian systems
and the known or inferred associated stream reach.
Species
Family
Constat Comments
LAMIACEAE
E
2/6 records – from rocky creek
Plectranthus
bank above falls on Gheerulla
torrrenticola
Ck; rocky outcrop in OF
(Walli SF-Kenilworth)
E
§ - single record from
Pterostylis chaetophora ORCHIDACEAE
Neerdie
SAPINDACEAE
E
4/4 records – 2 recorded
Cossinia australiana
from Teddington Weir area –
no ‘C’ habitat code; § confirmed in riparian habitat
EUPHORBIACE
V
21/22 records indicative of
Fontainea rostrata
AE
population stronghold;
several from riparian forest
(Teddington Weir)
MIMOSACEAE
V
§ - in wallum at Lagoons SA
Acacia attenuata
& nthn part of catchment +
Tuan SF
Acacia baueri ssp.
MIMOSACEAE
V
§ - in wallum at Lagoons SA
baueri
MYRTACEAE
V
2/6 records from upper
Syzygium
catchment rainforests;
hodgkinsoniae
possibly in riparian forest
MYRTACEAE
V
15/20 records – population
Xanthostemon
stronghold of riverine forest
oppositifolius
species (Kin Kin/Tinana Ck)
POACEAE
V
2/2 records - Obi Obi &
Arthraxon hispidus
Booloumba Ck - from creek
bank habitat
PROTEACEAE
V
17/19 records from rainforest
Floydia praealta
within area; obvious
population stronghold;
habitat not specified but
likely in stream-side forests
V
12/12 records; as above
Macadamia integrifolia PROTEACEAE
PROTEACEAE
V
15/31 records; generally as
Macadamia ternifolia
above
V
2/2 records from upper
Macadamia tetraphylla PROTEACEAE
catchment; generally as
above
SIMAROUBACE
V
11/14 records; many from
Quassia bidwillii
AE
creek banks (Tinana Ck
stronghold)
XANTHORRHOEAC
V
at least 8/15 records; some
Romnalda
EAE
from creek banks (e.g. Kin
strobilacea
Kin Ck)
Alyxia ilicifolia ssp.
APOCYNACEA
R
4/13 records – 1 specifically
E
from creek bank; most from
magnifolia
Australian Centre for Tropical Freshwater Research
Reach
M4
M41
M45
M41,
M44
M41
M41
M1, M2
M17,
M18
M41
M2, M3,
M14,
M18
M1, M2,
M14,
M41
M41
M41M45
M28
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Species
Family
Constat
CORYNOCARPAC
EAE
R
LAMIACEAE
R
Austromyrtus inophloia
MYRTACEAE
R
Callistemon formosus
MYRTACEAE
R
Choricarpia
subargentea
MYRTACEAE
R
Papillilabium beckleri
ORCHIDACEAE
R
Boronia rivularis
RUTACEAE
R
Cupaniopsis newmanii
SAPINDACEAE
R
Lepiderema pulchella
Symplocos harroldii
SAPINDACEAE
SYMPLOCACE
AE
R
R
Corynocarpus
rupestris ssp.
arborescens
Westringia blakeana
Australian Centre for Tropical Freshwater Research
Comments
Cooroy, Woolvi, Kin Kin
1/3 records on steep rocky
creek bank near Cooran
Reach
1 record only nth of
Mapleton; from creek bank
habitat
6/13 records; Kin KinMapleton; 1 record from
creek bank habitat
2/4 records -1 from near
Pomona & Boompa creek
bank record
9/16 records; pop. stronghold
from Brooyar-Imbil; 4 from
creek banks
2/3 records; 2 from creek
banks
3/13 records appear to be
from area; 2 from creek
banks; name also suggests
this habitat
single record from Kin Kin
creek bank; nthn limit?
1/2 records; from rainforest
7/10 records suggest
population stronghold Imbilupper catchment; several
from creek banks
?M18
M28
?M18
M21M37
?M18
M20,
M21
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Table 2 (cont.)
B.
Species that are not recorded from, or considered unlikely to occur within,
riparian systems.
Species
Cycas megacarpa
Family
CYCADACEAE
Plectranthus omissus
LAMIACEAE
Macrozamia pauliguilielmi
ZAMIACEAE
Marsdenia coronata
ASCLEPIADACEA
E
Allocasuariana rigida
ssp. exsul
CASUARINACEA
E
Baloghia marmorata
EUPHORBIACEA
E
Fontainea venosa
EUPHORBIACEA
E
Ricinocarpos speciosus
EUPHORBIACEA
E
Sophora fraseri
FABACEAE
Prostanthera palustris
LAMIACEAE
Cryptocarya foetida
LAURACEAE
Archidendron lovelliae
Picris conyzoides
MIMOSACEAE
ASTERACEAE
Senna acclinis
Neoalsomitra suberosa
CAESALPINIACEA
E
CURCURBITACEA
E
Australian Centre for Tropical Freshwater Research
Constat
Comments
E
2/6 records; 1 from
Little Eel Ck (Coast
Ra.) in OF; Kinbombi
south of Kilkivan
E
1/3 records from rock
ledge on SE summit
Mt Widgee
E
1/17 records from
hillslope above
Tinana Ck (sandy
high bank) ; others
from hillslopes, Mt
Woocoo summit
V
2/6 records from OF
in Imbil-Kandanga
area
V
single record from
OW on east side of
Mt Cooroora
(Pomona)
V
3/3 records from
mixed forest/rain
forest at Mt Pinbarren
V
4/4 records from
hillslope forests about
Brooyar, Glastonbury
V
3/9 records from
hillslope forest about
Cooroy-Cooran
V
1/2 records
(Kilkivan); other
record indicative of
OF habitat
V
3/3 records from
hillslope OF about Mt
Tinbeerwah
V
§ - from rainforest
near Mt Woolvi
V
§ - as above
R
2/2 records;
Kenilworth – nonriparian winter annual
herb
R
1/3 records, in OF nth
of Gympie
R
4/9 records – Imbil,
Kandanga, Blackall
Ra. – not riparian
plant but recorded (§)
from rainforest at Mt
Reach
M37
M36
M41
M21-M23
M28
M28
M36,
M37
M28
M37
M27
M41
M41
M4, M23
M8. M35
M20,
M21,
M23,
M41
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Species
Family
Constat
Westringia grandifolia
Acianthus amplexicaulis
LAMIACEAE
ORCHIDACEAE
R
R
Macrozamia longispina
ZAMIACEAE
R
Australian Centre for Tropical Freshwater Research
Comments
Woolvi
1/1 record; hillslope
2/4 records from near
Maleny
3/10 records Widgee
Mtn area; grows in
OF on ridges
Reach
M16
M35
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Review of the status of riparian vegetation and flora of the Mary River and associated systems.
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Table 2 (cont.)
C.
Species that are considered possibly as occurring within riparian systems but
where records within study area are unconfirmed, or where a species record is in the
immediate vicinity of the Mary River catchment watershed and there is indication of
riparian habitat affiliation.
Species
Eucalyptus conglomerata
Family
MYRTACEAE
Constat
E
Triunia robusta
PROTEACEAE
E
Pouteria eerwah
SAPOTACEAE
E
Ziera sp. (Monogorilby –
P. I. Forster)
RUTACEAE
V
Paristolochia
praevenosa
ARISTOLOCHIACE
AE
R
Thisma rodwayi
BURMANNIACE
AE
R
Argophyllum
nullemense
GROSSULARIACEA
E
R
Hernandia bivalvis
HERNANDIACEA
E
R
Eucalyptus decolor
MYRTACEAE
R
Rhodamnia pauciovulata
MYRTACEAE
R
Persoonia amaliae
PROTEACEAE
R
Comments
3/14 records (Beerwah)
- 1 “common in isolated
patches on creek banks”
21 records, none of
which are confirmed but
near Cooroy (Six Mile
Ck)
not confirmed, but in
2/5 records in vicinity of
Mt Eerwah/ Eumundi
district – habitat
affiliation not specified
single record of this
shrub from Amamoor;
no habitat details
no records confirmed
but 3/4 records with
creek bank habitat codes
– upper catchment if so
not confirmed in area
but 2/2 records from
creek bank habitat near
Cooloolabin (possibly
extends to upper Obi
Obi Ck)
not confirmed but 1/3 a
possibility in Coast Ra.
south of Biggenden;
creek bank habitat
1/2 records possibly in
area; habitat affiliation
unknown
1/5 records possibly
within area; 1 from
creek bank habitat
1-2/4 records from
rainforest near Mt
Bauple; habitat unclear
1/3 records possibly in
area; indication of
stream bank habitat
affiliation
Reach
M28
M33
M15,
M17
upstream
of M38
M11
While some rare/threatened taxa are predominantly associated with adjacent catchments,
ecosystems that contain them may straddle a watershed. An example of this is the distribution
of the ‘vulnerable’ species southern penda that spans the Noosa watershed. This species is
mainly restricted to the Great Sandy National Park and nearby areas on Kin Kin Creek of that
catchment. An outlying population, however, has also been located towards the northern end
Australian Centre for Tropical Freshwater Research
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ACTFR Report No.02/11
of the Tinana Creek sub-catchment at Teddington (van Kampen and Wedlock 2002:10).
Other proximal areas such as Poona National Park host ‘vulnerable’ species such as Acacia
attenuata in common with the adjacent area of the Tinana Creek sub-catchment of the study
area, and the ‘endangered’ Macrozamia pauli-guilielmi is also found within Tinana Creek
catchment as well as in the Police Paddock Conservation Park (van Kampen and Wedlock
2002:10) in sandy soils of the high banks of streams.
Many plant species found within the study area are of conservation interest also because they
are at or close to the limits of their known distribution. Examples of those at the northern limit
of distribution are cunjevoi (Alocasia macrorrhizos), Austromyrtus sp. (‘Brookfield’
L.W.Jessup 155), southern lawyer cane (Calamus muelleri), stinking cryptocarya
(Cryptocarya foetida), smooth tuckeroo (Cupaniopsis serrata), Cupaniopsis newmani, Deep
Creek fontainea (Fontainea rostrata), prickly ti-tree (Melaleuca styphelioides), native
wisteria (Milletia megasperma - syn. Callerya megasperma), small-leaf plum myrtle
(Pilidiostigma rhytispermum - syn. Sauropus trachyspermus), native guava (Rhodomyrtus
psidioides), rose marara (Pseudoweinmannia lachnocarpa), raspy root (Rhinerrhiza
divitiflora), and silky bramble (Rubus moorei). Others at/near their southern limit of
distribution include a mistletoe (Amyema conspicua ssp. conspicua), Arytera oshanesiana,
Emmenasperma cunninghamii, Mackinlaya macrosciadia, green-leaved silkpod (Parsonsia
latifolia), Phyllanthus novae-hollandiae, blunt-leaved coondoo (Planchonella myrsinoides),
felt fern (Pyrrosia confluens var. dielsii) and vitex (Vitex acuminata - syn. V. melicopea) (van
Kampen and Wedlock 2002:37). Several of these also are associated with riparian habitats
and may be at risk from water infrastructure developments and/or flow regime modification.
In addition, there are many other taxa that are listed as common but restricted plants under
Schedules of the Nature Conservation Act (1992) and the Nature Conservation and Other
Legislation Amendment Regulation (No. 1) 2000 (Subordinate Legislation 2000 No. 354,
Government of Queensland). These include ‘collectable’ orchid species and several others,
e.g., Banksia integrifolia (Rider and Wedlock 2000), used commercially. Some may be
linked with riparian zones and wetlands and may be impacted by water resource development,
however, the legislation explicitly precludes unregulated “taking, using and keeping” of said
plants but makes no provision for mitigating other impacts.
Riparian systems also constitute very valuable faunal habitat and provide wildlife movement
corridors throughout the landscape. Of particular importance for maintaining faunal habitat is,
therefore, the maintenance of integrity of riparian systems and the curtailment of wetland
drainage. Water resource developments such as off-stream storages, can, in fact, advantage
several of these species. But because of the significant disruption of the riparian verge, instream storages are problematic. Further problems can arise from water abstraction to the
extent that the quantum of water within a system is insufficient to provide for maintenance of
in-stream and near-stream communities that furnish sustenance and shelter resources for these
animals. Problems can also derive from supplementation that either disrupts these systems’
natural floristics and/or advantages exotic species invasion that, in turn, changes the resource
base.
4.3.
Biodiversity Hot-spots/Significant Areas.
Certain localities/areas within the wider study area, by virtue of their landscape situation
and/or condition, will contribute relatively more to the local and regional biodiversity than
other often more extensive areas. These loci of high habitat and/or species diversity and/or
integrity/representativeness may be referred to as biodiversity ‘hot-spots’ – i.e. locations of
high conservation significance. Tinana Creek is renown as one such area, and one that has
been the focus of recent detailed biodiversity investigations (van Kampen and Wedlock 2002)
that have been cited frequently above.
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Wetlands, both ‘non-linear’ (lentic) wetlands such as perennial or seasonal marshes, swamps
and mangroves, and ‘linear’ (lotic) wetlands such as streams or rivers, are such places. This
is particularly so in the Australian context where much of the land is inherently dry, at least
seasonally, where moisture is one of the greatest limitations to ecological productivity. These
are functionally vital landscape components, to such an extent that they are frequently
referred to as the “ecological arteries” of the landscape (Sattler 1993:161).
4.4.
Wetlands.
Wetlands are amongst the world’s most productive ecosystems (Mitsch and Gosselink 1993)
and support high habitat diversity due to the influence of both land and water (Brady and
Riding 1996:5). They sustain plant and other aquatic communities that reflect improved
moisture conditions and superior soils due to nutrient in-washing at lower parts of the
landscape (Reich 1998:14). It is estimated that more than half of Australia’s wetlands have
been drained or reclaimed and destroyed since European settlement (Anon. 1998) and those
that do remain are some of the continent’s most threatened systems. This is particularly so
along the eastern seaboard, including the Sunshine Coast district, where agricultural and
residential development is concentrated.
Wetlands, both ‘non-linear’ (lentic) wetlands such as perennial or seasonal marshes, swamps
and mangroves, and ‘linear’ (lotic) wetlands such as streams or rivers, are examples of such
places. These are so important landscape features in the Australian context where much of
the land is inherently dry, at least seasonally, and where moisture is one of the greatest
limitations to ecological productivity. These are functionally vital landscape components, to
such an extent that they are frequently referred to as the “ecological arteries” of the landscape
(Sattler 1993:161).
It has been demonstrated that vegetation associated with linear wetlands often constitutes
residual occurrences of endangered REs such as 12.13.1 (notophyll gallery rainforest on
alluvial plains). Lentic wetlands also comprise remnants of endangered REs, such as
12.9/10.12 (eucalypt-bloodwood-paperbark woodland on seasonally waterlogged sediments)
(Young and Dillewaard 1999:12/59-12/60). Ecosystems classified as ‘of concern’ also include
sedgelands and paperbark swamp forest/woodland associated with coastal dune-swale
systems (12.3.8 and 12.3.5, 12.3.6).
The greatest significance is ascribed to those wetlands that are given international recognition
under the RAMSAR Convention. There is one of such pre-eminent status into which streams
of the study area flow. This is the Great Sandy Strait (encompassing an area of 9 316 000 ha –
Young 2001:25) and one of the five recognised within the State. Another significant wetland
system, the Burrum Coast, is classified as nationally important (Blackman 2001:67). This
designation confers upon properties so classified an importance at the national level. This may
be due to they being considered as good examples of wetlands within a biogeographic region,
and/or due to important ecological or hydrological role, and/or importance as faunal habitat,
and/or that they support native plant or animal taxa or communities which are considered
endangered or vulnerable (Usback and James 1992:1-3, Larmour 2001).
In addition, some of the wetlands (along with sites in the ranges) within the study area also
contain the Type Localities (i.e. locations at which an organism was collected and first
described) of several species. For example, the Mary River Turtle’s Type Locality is “Mary
River, 45.5km S. - 21km W. of Maryborough” (Cann, 1998:248). This confers measures of
significance that are currently accommodated within State planning processes.
Again due to extensive clearing associated with expansion of agricultural and residential land
uses, much of the catchment (i.e. 58% - van Kampen and Wedlock 2002:8) has lost its
original vegetation cover, with that which remains, particularly within the lowlands, highly
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residual and fragmented. Most of the district’s natural values, therefore, are associated with
these remnants. This understanding immediately prompts consideration of the importance of
landscape connectivity.
4.5.
Landscape Connectivity.
Within the context of increasing human transformation of the landscape it is readily
understood that regional biodiversity maintenance is predicated on maintaining links among
the various patches of predominantly native vegetation that remain. Catterall (1993) has
clearly demonstrated that the riparian zone is important habitat for a range of terrestrial fauna.
Its importance during climatically challenging periods may be substantial (Williams 1994).
Not only do riparian zones furnish habitat, they also facilitate faunal movement about the
landscape. In a review of riparian zone management in Queensland and the Northern
Territory, Sattler (1993:161) sets out a variety of studies that demonstrate the wildlife
significance of the riparian zone. These include documented declines and local extinctions of
birds ascribed to loss of riparian vegetation, the importance of these zones in facilitating
wildlife movement (as shown by herbivorous turtle distribution and abundances
corresponding with the distribution and density of riparian vegetation) and the evolutionary
significance of gallery forest in allowing reinvasion of monsoon forest patches by habitatdependent vertebrates.
While riparian corridors are commonly recognised as animal movement corridors they also
play a potentially significant role in plant dispersal. Clearly, moving water can transport plant
fruits, seeds and stem fragments that can establish downstream. In addition, riparian zones
can be major sources of plant recruitment over extensive areas of the landscape, especially
during periods of rapid climatic change because of the favourable microclimate along stream
valleys (Gregory et al. 1991:543).
In heavily developed catchments, remnant riparian areas are typically narrow, noncontinuous, and suffering from weed invasion and other edge effects such as fire damage (e.g.
Petroeschevsky 1997). Many existing riparian areas are poor representatives of what were
once diverse and sometimes extensive vegetation communities. As a result their value as
corridors and refuges for wildlife is likely to have been already reduced, but is still considered
highly significant.
Large tracts of state forest with native vegetation, particularly west of Tinana Creek, perform
an important ecological function in providing refugia and linkages for native flora and fauna.
The mostly narrow corridors within pine plantations and remnants on private land are much
more limited in extent but also play an important role (van Kampen and Wedlock 2002:8).
These investigations reveal that remnant ecosystems as a whole within the Tinana Creek subcatchment have already been diminished to the critical threshold required to avoid significant
loss of biodiversity. This situation is worse than in the Southeast Queensland bioregion
overall, as well as within the Mary River catchment generally. Such a low level of native
vegetation retention can also be problematic in terms of the potential for decreased water
quality, increased salinity and other forms of land degradation, not to mention habitat for rare
and/or threatened species of flora and fauna. However, the large areas of exotic slash pine
plantation, which have replaced native vegetation over 34% of the sub-catchment, have
somewhat compensated for the extent of land clearing and appear to have provided a buffer
against the emergence of these problems (van Kampen and Wedlock 2002:10).
Because of the extent of disruption of the middle to lower reaches of the Mary, riparian
vegetation reinstatement and the rehabilitation of links between remnants to provide wildlife
corridors is a recent major focus of interest (see Stockwell 2001; van Kampen and Wedlock
2002). Strategic rehabilitation of degraded stream reaches throughout the Mary River
catchment, both in attempt to restore in-stream and near-stream habitat and to promote
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increased connectivity of remnants (described as catchment “assets”), is a principal objective
of Stockwell (2001). Opportunities for west-east linkages across the Tinana Creek subcatchment providing for connectivity of remnants from the low coastal ranges to the sandy
coastal plain and south-north along the interfluve between the Mary itself and Tinana Creek
have been documented by van Kampen and Wedlock (2002). It is important that water
resource planning takes into account such opportunities for environmental repair and remnant
linkage so that such opportunities are not lost.
4.6.
System Integrity and the Spread of Exotics and Pest Species.
A considerable proportion of the region’s flora comprises exotic species. Several species are
particularly prominent in the Mary system. These comprise chiefly, Chinese elm, camphor
laurel, both species of privet, cat’s-claw creeper, madeira vine, balloon vine (Cardiospermum
grandiflorum), lantana, groundsel (Baccharis halmifolia) and guava (Psidium guajava).
Because the riparian zones are often the most environmentally equable parts of the landscape,
there is likely to be a prevalence of such weedy species within these systems. All are
prevalent in many places within the riparian zone, and, with regard to some of the giant
grasses, can grow within the stream itself. As mentioned previously, alien invaders such as
Chinese elm, camphor laurel, lantana and privets are now dominating the riparian community
structure, along with vines such as cat’s-claw creeper and madeira vine. Infestations are
particularly prevalent along the following stream reaches:
i.
ii.
iii.
iv.
v.
vi.
vii.
about the Mary main channel downstream of Conondale to the confluence of Little
Yabba Creek;
Mary River downstream of Kenilworth to a point east of Imbil;
along the Gympie reach of the Mary from the Six Mile Creek confluence to about the
Wide Bay Creek junction;
Mary River downstream from above Tiaro to the Mary River barrage;
along Obi Obi Creek about Maleny;
the middle to lower reaches of Amamoor Creek; and
along the middle to lower reaches of Glastonbury Creek (Pickersgill 1997).
It is notable that several of these problem plants have arisen from deliberate introductions for
pasture “improvement” or, in the case of the extraordinarily aggressive leucaena that is now
invading riparian verges within parts of the catchment, stock forage.
Interference with the flow regime of streams can predispose these parts of the landscape to
severe weed invasion. Flow supplementation, for instance, can render areas adjacent to
channels more susceptible to the establishment of exotics because of an elevated quantum of
water and an increase in the wetted perimeter about the channel, together with a greater
reliability of its delivery throughout the year.
Increases in water levels within supplemented channels interact with channel morphology to
provide niches for exotic plant establishment. This can favour the growth of exotic, semiaquatic ponded-pasture grasses such as Pará grass (Brachiaria mutica) over native species.
This is a rapidly growing stoloniferous perennial reaching 2m in height (Sainty and Jacobs
1981:169). Pará grass grows in damp areas, on dry ground in high rainfall areas and is
capable of forming floating mats in deeper water. Stolons (or ‘runners’) may be up to 5 m
long and root from the nodes (Sainty and Jacobs 1981:169). It spreads mainly through
vegetative means, such as through dislodged stolons and culm fragments. There is great
advantage in such a reproductive method in that resources can be shared amongst culms
sharing a common root system (Stuefer et al. 1998). Pará grass can, once established, flourish
to interfere with the hydraulic conductivity of streams (Bunn et al. 1998) and, most
significantly, with the ecology, particularly with regard to carbon transfer and habitat
structure, of both in-stream and near-stream communities (Bunn et al. 1997).
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In contrast, water abstraction can desiccate stream verge habitats making them susceptible to
invasion of the more xeric (drought-tolerant) exotics such as grader grass (Themeda
quadrivalvis), molasses grass (Melinus minutifolia) and Guinea grass (Panicum maximum)
that would have previously been excluded due to light limitations associated with the
existence of a former mesic forest canopy. A more xeric community will be more prone to
fire damage to an extent that the vegetation about streams may become almost
indistinguishable from the surrounding open sclerophyll communities, with a consequent
reduction in the stream-regulatory function than would normally be associated with the
riparian verge.
Other factors associated with water resource development such as fluctuations in water levels
during weir release operation can also advantage exotic species. This constitutes another
aspect of disturbance at amplitudes or at particular times of the year hitherto not experienced
by local native systems. Sudden fluctuations in water levels can impact on the in-stream
(aquatic macrophyte) as well as near-stream (riparian) vegetation communities. This is
especially so given the fact that some plant species span the boundary of the terrestrial and the
aquatic (see Mackay, associated report). Impacts on aquatic macrophyte assemblages
resulting from sudden changes in water level have been noted in the littoral zones of
reservoirs used for hydro-electric power generation, where water fluctuations of several
metres may occur over short periods of time (Henriques 1987, and Rørslett and Johansen
1996 cited by Mackay, associated report). Walker et al. (1994) found differences in the
aquatic macrophyte assemblages of weir pools in the Murray-Darling were associated with
water level fluctuations. Such changes have considerable implications for the condition of the
near-stream vegetation communities.
There is a suite of direct and indirect influences that arise from exotic species invasion. The
most apparent of direct influences is associated with niche occupation that precludes or
inhibits native species occupying a given site. In some circumstances, possibly as in the case
of the aromatic Japanese sunflower (Tithonia diversifolia), exotic species can also directly
inhibit recruitment and site occupation of other native species through allelopathy – i.e. by
secreting toxic phytochemicals or via foliar leachates. Indirect effects can occur through
competition for limited resources that disadvantages native species. They can also derive
from the additional fuel loads and greater flammability (due to constituent volatile
compounds) of many exotic plant species. This is particularly so in the case of molasses
grass, Guinea grass and lantana (Wallmer 1994; Sheehy 1996).
Further indirect implications arise from the invasion of exotic pasture (and associated)
species. Schultz and Walbank (1995) found that degraded riparian areas encourage the
growth of exotic grasses that in turn provide prime habitat for other pests such as the Cane
Rat (Rattus sordidus) that is a serious problem for optimal sugar cane cultivation (Brodie
1996). It is readily apparent that by restoring the riparian zone and restricting growth of Pará
grass and Guinea Grass pest rat harbourage can be greatly reduced (Tucker 1995; Tucker and
Brodie 1996).
5.
CONDITION OF THE RIPARIAN VEGETATION.
The functional significance of the riparian zone is well documented. Influences range from
structural controls on channel form, hydraulic conductivity and erosion and sediment/nutrient
transport, through direct influences on water quality, and primary carbon sources for aquatic
system production to productivity and biodiversity ‘hotspots’, wildlife refuges and corridors
within the wider landscape. The distinctiveness and functional importance of riparian systems
along upland, confined streams differs to that of the higher order, unconfined streams that
occur in lowland areas. Lowland streams and rivers are typified by complex channels,
extensive floodplains and by broad and complex riparian systems. Here there is generally a
Australian Centre for Tropical Freshwater Research
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diverse array of geomorphic surfaces with plant communities of various ages reflecting fluvial
disturbance and with riparian systems that are often quite different from communities
upslope. These zones typically feature species that are specially adapted to valley floor
environments (Gregory et al. 1991:542).
Given the great disproportionality of the ecological significance of riparian zones compared
with their low spatial extent in the landscape it is vital to ensure that water resource
developments do not adversely impact on them. Accordingly, effective water allocation
management planning requires accommodation of the environmental flow needs of the
riparian zone and an understanding of the implications of water resource development –
including both the emplacement of infrastructure and altered flow regimes – on the condition
of these near-stream vegetation communities.
Of central importance is consideration of perturbations to riparian vegetation systems brought
into play by stream regulation and water resource development. The Mary River supports
systems that have been considerably modified by in-stream structures and other activities in
which flows have been significantly regulated. It represents an essentially perennial stream
wherein baseflows have been increased by regulation and where large weirs have resulted in
channel impoundment. Other types of regulation can result in supplementation of intermittent
streams (particularly tributary streams) to the extent that they can be transformed into
perennial systems. Investigation and monitoring of the plants and vegetation generally both
within and adjacent to the stream channel can allow for determination of extent of impacts
associated with flow regulation and inferences regarding acceptable limits of change.
There are “complex interrelationships among plants and hydrogeomorphic processes
operating on floodplains ... [that lead to great] difficulties associated with understanding,
generalising and predicting the effects of human modification of streamflow on natural
ecosystems” (Carter Johnson 1994:45). It is the intention here to attempt to ‘tease out’ those
impacts on the condition of riparian communities that can be reasonably attributed to flow
modification of riverine systems and associated water resource development.
In addition, dieback of both eucalypts and casuarinas is prevalent in southeast Queensland
(Wylie et al.1993a) and its incidence within the Mary system has been the subject of intensive
investigation (Wylie et al. 1993b). In this system, this problem is particularly evident for
river sheoak (C. cunninghamiana) about the main channel between Conondale and
Kenilworth in the upper catchment, downstream of Gympie and along the middle to lower
reaches between Miva Gauging Station and Tiaro, and along Wide Bay Creek (in the vicinity
of Kilkivan), Amamoor and Widgee Creeks. It is notable that Wylie et al. (1993b:11)
established a significant relationship between stream water quality indicators and severity of
river sheoak dieback, with dieback progressively more severe with increasing levels of stream
water salinity. A similar but less strong relationship was also found for eucalypt dieback.
These workers considered that there was covariance in salinity levels and the extent of
clearing and other landscape disruption at sites, where severe dieback coincided with poor
water quality in localities that were heavily cleared and cultivated/grazed areas (e.g. around
Kilkivan). This study points to the increasing risks of dryland salinity associated with
catchment clearing resulting in the removal of deep rooted trees and the subsequent rise in
local water tables bringing salts from the soil profile to plant root zones with great
consequences for landscape health sens. lat.
5.1.
Methods.
Current environmental conditions in non-tidal reaches were determined in relation to
geomorphology, water quality, riparian vegetation, aquatic vegetation, macroinvertebrates,
freshwater fishes; and the overall condition of estuarine and marine environments was
Australian Centre for Tropical Freshwater Research
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Review of the status of riparian vegetation and flora of the Mary River and associated systems.
ACTFR Report No.02/11
assessed. Different methodologies were used to carry out the assessments in each case.
However, in all cases, current conditions were rated on the following five-point scale:
•
•
•
•
•
1
2
3
4
5
-
natural/near natural, imperceptible change from natural;
minor modification from natural;
moderate modification from natural;
major modification from natural;
severe (unsustainable) modification from natural.
The condition of riparian vegetation was determined from rapid site assessment during a TAP
fieldtrip held in May 2001. This was complemented by information was drawn from aerial
photographic interpretation and consultation with extension and agency officers (e.g. B.
Wedlock, (MRCMA) and W. MacFarlane (EPA)) and other personnel.
With regard to this ecosystem component, the factors considered include continuity and
intactness of the riparian community, broad structure and floristics, extent of canopy cover
and presence/abundance of exotic (weed) species. In the first instance the assessment
methodology developed during the course of the Snowy Water Inquiry (SWI) (Young et al.
1998) was adapted to provide an ordinal metric of condition. This is comparable to the
approach utilised by DNR&M’s State of the Rivers team (Johnson 1997). Those vegetation
assessments are site-specific and not necessarily representative of conditions along the entire
the length of any given reach.
For the catchment as a whole, the work undertaken during October 2001 by DNR&M’s State
of the Rivers team (Johnson 1997) provided additional information for scoring the existing
condition of riparian vegetation along the Mary and Burrum Rivers and Beelbi Creek.
Data obtained from the earlier assessments, complemented by interpretation of the most
recent aerial photography at a scale of 1:25 000, were used to compile a basin-wide condition
appraisal of the riparian systems. Given the lack of resources for extensive site survey,
assessments detailed below are highly reliant on earlier work.
5.2.
Consideration of Existing Condition.
Condition ratings for the various river and stream reaches of the Mary WRP study area are set
out below in Table 3. It is readily apparent from this table that the condition of riparian
vegetation along the various stream reaches evaluated for the Mary WRP ranges from very
good to almost non-existent – i.e. from situations of negligible change to major modifications
from original condition. The current state of the riparian zone can be due to adverse impacts
arising from a variety of land use practices or from other factors, as well as from impacts
associated with water resource development such as the emplacement of infrastructure and
flow regulation, or some combination thereof.
5.2.1. Impact of factors unrelated to water resource development.
There are many factors exclusive of those that are associated with stream regulation and other
water resource development activities that impinge on the condition of riparian systems. The
foremost of these is clearing, which has frequently been undertaken right to the water’s edge.
This is a direct impact on the near-stream community that has major consequences for
associated aquatic communities – i. e. removal of the thermo-regulatory and shelter and food
resource function – as well as for the physical stability of the stream banks. Moreover, this
provides an avenue for colonisation by exotic weed species, with a variety of implications that
were set out in section 4.6 above.
Australian Centre for Tropical Freshwater Research
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Review of the status of riparian vegetation and flora of the Mary River and associated systems.
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The very existence of a host of exotic species - most of which were deliberate introductions
for a range of purposes, not the least being for stock fodder - constitutes a factor totally
unrelated to water resource development. The type and abundance of weed infestation can
have significant consequences for the integrity of the remaining riparian verge, particularly
with regard to fire proneness (see Wallmer 1994), and is likely to inhibit any natural recovery
in the absence of further clearing.
Stock itself is an alien introduction that can wreak major impacts on the riparian zone both
through destruction of ground cover and understorey plants by grazing and through trampling,
compaction and erosion instigation (Jansen and Robertson, in press). Stock excrement can
also provide nutrients at levels far in excess of natural levels within the riparian zone,
particularly at watering access points. This can significantly modify the floristics and
structure of the riparian community. It can distinctly advantage exotic species at the expense
of native riparian constituents and, when transported into the stream, will have adverse
impacts on water quality and implications for aquatic community composition, structure and
functioning.
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Review of the status of riparian vegetation and flora of the Mary River and associated systems.
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Table 3: Description and assessment of the condition of the riparian verge at selected
sites representing various reaches of major streams within the Mary WRP study area
[Note that the standard riparian rapid assessment pro forma was employed generating
percentile scores for condition that are ranked as follows:≥ 90 = 1 (very good condition negligible change from natural); 75-89 = 2 (good condition – minor change from
natural); 60-74 = 3 (moderate condition - moderate change from natural); 40-59 (poor
condition – major change from natural); < 40 = 5 (very poor condition – very major
change from natural)].
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
Flagstone
Creek to
Conondal
e
M1
Conondal
e to
Cambroo
n
M2
Cambroo
n to Obi
Obi Creek
M3
Obi Obi
Creek to
upstream
of Moy
Pocket
gauging
station
Upstream
of Moy
Pocket
gauging
station to
Yabba
Creek
M4
two field sites examined (8, 9); minor–moderate change from
pre-European condition at both sites Casuarina
cunninghamiana, Melaleuca bracteata dominants with
conspicuous exotic component of pasture grasses, ruderals &
rank shrubs
gw9 (Conondale), dj116 (Mary River at Eastern Mary River
Road Crossing), dj115 (Mary River along Eastern Mary River
Road) - all three sites rated as having undergone moderate
change from natural – at gw9 structural disruption was evident
associated with rock revetement of one bank and abundant
weed growth; dj116 possessed similar impacts and ranked
lower (i.e. score 60 compared with 68); the narrow riparian
verge at dj115 was rated similarly to gw9; the reach naturally
supports a C. cunninghamiana dominated verge, but weeds
such as *Ricinus communis, *Ligustrum sinense,
*Cinnamomum camphora, together with various rank grasses,
ruderal forbs & vines such as *Passiflora spp. & *Solanum
seaforthianum.
highly variable riparian vegetation condition – significant
remnant wet sclerophyll/rainforest downstream of Little Yabba
Creek but the lower part of the reach has undergone major/very
major disturbance.
two sites examined (7, 10); minor change from pre-European
condition – C. cunninghamiana, & mesic spp. (e.g.,
Castanospermum australe, Aphananthe philippinensis,
Araucaria cunninghamii, Grevillia robusta, Ficus sp.)
dominants with exotic component of vines (*Andrera
cordifolia at one site), pasture grasses & rank shrubs present
variable riparian vegetation condition; two sites examined (6–
60); minor to major change from pre-European condition;
dominated by Casuarina cunninghamiana at both sites but site
6 in drier location influenced by recent plantings & mesic
Waterhousea floribunda at site 60; weeds such as *A.
cordifolia, *R. communis, & *Phalaris sp. present.
River/
Stream
Reach
Name
Mary
River
M5
variable vegetation condition - two sites checked (site 58 –
Mary River at Walker’s Bridge & site 59 – Mary River at Moy
Pocket); condition of rip. verge very good (at 59) to moderate
(at 58);
C. cunninghamiana prominent at both sites, W. floribunda only
at site 58 & Angophora floribunda at 59; weeds (grasses,
ruderals & lantana) frequent at 59.
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ACTFR Report No.02/11
River/
Stream
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
Yabba
Creek to
Six Mile
Creek
Six Mile
Creek to
Eel Creek
M6
Eel Creek
to
Glastonbu
ry Creek
M8
Glastonbu
ry Creek
to Wide
Bay
Creek
M9
Wide Bay
Creek to
Munna
Creek
M10
Munna
Creek to
upstream
limit of
Mary
Barrage
pondage
M11
single site (57) checked; rip. verge condition poor;
dominated by C. cunninghamiana & W. floribunda with minor
Eucalyptus tereticornis, Callistemon viminalis; a range of
exotics present in significant infestations.
single site (12) checked; rip. verge in poor condition;
dominated by Casuarina cunninghamiana, Callistemon
viminalis & some *Celtis paniculata; other weeds (especially
grasses & *R. communis) abundant.
single site (Mary River at Fisherman’s Pocket – site 13)
checked; rip. verge in good condition; dominated by
Tristaniopsis laurina, C. cunninghamiana, W. floribunda, &
M. bracteata; the exotics *Leucaena leucocephala & *Celtis
paniculate locally frequent; other weeds present were mostly
ruderals
variable riparian vegetation condition inferred from aerial
photographic interpretation;
one site (Mary River at Bell’s Bridge – site 30) documented;
rip. verge condition very poor ; dominated by *Panicum
maximum & *L. leucocephala; other weeds such as balloon
vine, Cardiospermum grandiflorum, locally abundant
variable vegetation condition; two sites (site 14 – Mary River
at Dickabraum Bridge & site 15 – Mary River at Marian
Banks) documented; rip. verge condition variable from poor (at
site 14) to very good ( at site 15); dominated by Callistemon
viminalis, Casuarina cunninghamiana & W. floribunda; weeds
such as *Glycine sp. and coarse exotic grasses present at site
14 but minor (apart from occasional *Psidium guajava) at site
15.
two sites inspected - gw17 (Mary River at Home Park) and
dj?? (Mary River at Emery’s Bridge); rip. verge in very good
condition at gw17; dominated by Callistemon viminalis,
Melaleuca bracteata (plus M. styphelioides at Emery’s
Bridge), Casuarina cunninghamiana, E. tereticornis with
minor W. floribunda; weeds (*Ricinus communis, *Melinus
minutifolia) very minor; at the Emery’s Bridge site, while the
rip. community was assessed to be in good condition at
Emery’s Bridge, minor vine tangles of *Cardiospermum
grandiflorum & *Ipomoea cairica present along with minor
ruderals.
Reach
Name
M7
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ACTFR Report No.02/11
River/
Stream
Little
Yabba
Creek
Obi Obi
Creek
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
Mary
Barrage
pondage
M12
variable vegetation condition, from good to poor; sites 16
(Mary River at Petrie Park), 28 (Mary River at Lynne’s
property) & 18 (Mary River at Tidal Barrage) inspected;
condition of rip. verge good at site 16 with locally dominant
Callistemon viminalis, & frequent W. floribunda, M. bracteata
& E. tereticornis, moderate at site 28 where the rip. verge is
dominated by E. tereticornis with Guoia semiglauca & A.
philippinensis but with weeds (e.g. *P. guajava, *Celtis
paniculata) often abundant; here the barrage pondage has
drowned the natural proximal verge vegetation, so that tall
open forest abuts the water’s edge without rheophyte zone; at
site 18, exposed rock on north banks inhibits vigorous tree
growth, here both M. bracteeata & Callistemon viminalis are
locally abundant whereas the exotic *L. leucocaphala is
abundant, along with rank grasses & ruderals
Downstre
am of
State
Forest to
Mary
River
Maleny
Weir to
upstream
limit of
Lake
Baroon
M15
no sites examined
M16
Baroon
Pocket
Dam to
Obi Obi
M18
Obi Obi
to Mary
River
M19
the upstream end of reach near Maleny has a highly modified
riparian zone
the naturalness of the riparian zone increases downstream
through Gardner’s Falls towards Barron Pocket Dam; two sites
(1,2) checked; rip. verge condition varies from moderate (1) to
good (2); dominants include mixed mesic spp. (2) e.g.,
Neolitsea dealbata, Elaeocarpus grandis plus *Cinnamomum
camphora, *Ligustrum spp. (1); range of weeds prevalent at 1
& minor at 2.
single site (3) checked; rip. verge in very good condition; range
of tall open forest/mesic dominants –e.g., Eucalyptus pilularis,
Lophostemon confertus, Allocasuarina littoralis,
E. grandis, Acacia spp, Archontopheonix cunninghamiana, W.
floribunda; currently there is little discernible change from
natural, apart from very minor weed presence; however, more
significant changes are likely to occur in the longer term in
response to flow regime change resulting from Baroon Pocket
Dam
two sites (4,5) checked; rip. verge in moderate condition;
dominants include Castanospermum australe &
*Cinnamomum camphora at both sites, Acacia spp. &
Aphananthe philippinensis (site 4) & W. floribunda, together
with Elaeocarpus grandis at site 5; weeds particularly evident
at 4, less so at 5.
Reach
Name
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Review of the status of riparian vegetation and flora of the Mary River and associated systems.
ACTFR Report No.02/11
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
Borumba
Dam to
upstream
limit of
Imbil
Weir
pondage
Imbil
Weir
pondage
Imbil
Weir to
Mary
River
Upstream
of
Kandanga
Upper to
Mary
River
Upstream
of dam
site to
State
Forest
boundary
M21
single site (at No. 6 Deep Crossing - 56) checked; rip. verge in
good condition; dominants include C. cunninghamiana,plus W.
floribunda, Castanospermum australe & other mesic spp.;
weeds (ruderals) minor changes in riparian community
composition are likely to occur in the longer term in response
to flow regime change resulting from Borumba Dam
M22
single site (at Imbil - 55) checked; rip. verge condition
moderate; dominants = C. cunninghamiana, *Cinnamomum
camphora &,Callistemon viminalis; weeds prevalent
no sites examined
State
Forest
boundary
to Mary
River
M26
Six Mile
Creek
Dam to
Louis
Bazzo
Drive
M28
Louis
Bazzo
Drive to
Mary
River
M29
River/
Stream
Reach
Name
Yabba
Creek
Kandanga
Creek
Amamoor
Creek
Six Mile
Creek
M23
M24
single site (Highgate - 54) checked; rip. verge mod. to good
condition; dominants = Castanospermum australe,, Casuarina
cunninghamiana, Ficus sp.; *Lantana camara often locally
dominant
M25
single site (at gauging station - 53) checked; rip. verge in good
condition;
dominants are W. floribunda, Ficus coronata, Acmena
hemilampra, Acacia melanoxylon,*Lantana camara; other
weeds, including *Ligustrum sinense, present within a
relatively structurally intact but floristically modified
community
sheoak islands; two sites (51,52) checked; rip. verge assessed
as in moderate (at Mary Valley Rd Bridge -51) to good (at
Amamoor - 52) condition; dominated by C. cunninghamiana,
Callistemon viminalis, W. floribunda, Castanospermum
australe & *Cinnamomum camphora; other weeds extensive at
51 & present at 52.
rainforested stream; closed canopy. two sites – (immediately
below Lake McDonald – 49 & below spillway - 50) checked;
rip. verge in very good condition; dominated by a range of
mesic spp., the most abundant of which included W.
floribunda, Acacia melanoxylon, Eucalyptus grandis & Ficus
coronata; Lophostemon confertus,frequent at 49 ; very
localised weeds include *Lantana camara (at 49) &
*Cinnamomum camphora & *Desmodium sp. (at
50)
rainforest stream; closed canopy at four sites from Woondum
Rd to the Victor Giles Bridge at Cooran (44, 45, 46, 47)
surveyed; all show rip. verge in very good condition;
dominants include W. floribunda Aphananthe philippinensis,,
Acmena hemilampra, Ficus coronata; *Lantana camara only
prominent weed at 45; *Macfadyena unguis-cati noted by
Pickersgill (1997)
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Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
Headwate
rs to
upstream
limit of
Cedar
Pocket
Dam
pondage
Cedar
Pocket
Dam to
junction
with north
branch
M30
rainforest stream; closed canopy; single site (at Tatnell Bridge
- 43) checked; exotic *Cinnamomum camphora dominates
with W. floribunda, *Ligustrum sinense,
A. philippensis & Acacia melanoxylon; condition moderategood, with a structurally intact verge floristically contaminated
by woody weeds.
M32
Junction
with north
branch to
Mary
River
M33
State
Forest to
Mary
River
State
Forest to
Eel Creek
M34
Glastonbu
ry Creek
Upper
Glastonbu
ry to
Mary
River
M36
Widgee
Creek
Gympie–
Woolooga
Road to
Mary
River
Kinbombi
Creek to
Mary
River
M37
rainforest stream; closed canopyindigenous rainforest largely
replaced by exotic *Celtis paniculata & *Cinnamomum
camphora forest (downstream of Saxelby Bridge – site 41) rip.
verge; dominated by Waterhousea, *Ligustrum sinense: other
weeds (especially ruderals) prevalent; site 42 (at Gear Bridge)
in basically very poor condition, with rank grass & a range of
other exotic infestations in a very structurally disrupted
community.
riparian verge highly disturbed about Gympie; single site
(Gympie outskirts – site 11 – score 10%) checked; rip. verge in
very poor condition; dominated by *Cinnamomum
camphora,& other weeds; minor Callistemon viminalis,
Casuarina cunninghamiana & Melaleuca bracteata present;
some riparian revegation works evident.
single site (at Gympie-Woolooga Road Bridge – site 36)
checked; rip. verge in mod.–good condition; dominants are W.
floribunda, C. cunninghamiana, Callistemon viminalis; weeds
abundant –e.g. exotic pasture grasses & balloon vine
two sites (at Chapman Bridge – site 37 & at Thomas Whitmore
Bridge – site 38) checked; rip. verge in mod. (38) to good (37)
condition; dominated by *Celtis paniculata, Eucalyptus
tereticornis & Castanospermum australe; weeds (lantana,
balloon vine, *Gallinsoga parviflora) abundant.
gahnia, she-oak on bars; single site (at Glastonbury – site 35)
checked; rip. verge dominants are Callistemon viminalis,
Maclura cochinchinensis, Ficus coronata, F. fraseri,
Allocasuarina torulosa, *Cinnamomum camphora; other
weeds (eg, *Macfadyena unguis-cati) frequent; verge in poormoderate (72%) state.
two sites (site 31 & site 34 at Widgee) checked; rip. verge in
poor (34) to mod. (31) condition, respectively largely due to
the presence of weeds; dominants = Ficus coronata,
Callistemon viminalis, C. cunninghamiana, W. floribunda &
*Celtis paniculata; other weeds abundant.
poor conditions observed at Kilkivan Gauging station; two
sites (at Brooyar – site 29 & at Kilkivan – site 33) checked;
rip. verge in very poor (at 33) to good (at site 29) condition;
Callistemon, Allocasuarina torulosa & Eucalyptus tereticornis
dominate site 29 but weeds (especially rank grasses &
*Tithonia diversifolia dominate site 33.
River/
Stream
Reach
Name
East Deep
Creek
Eel Creek
Pie Creek
Wide Bay
Creek
M35
M38
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ACTFR Report No.02/11
Reach
Name
Munna
Creek
Marodian
gauging
station to
upstream
of
Glenecho
School
Upstream
of
Glenecho
School to
Mary
River
Upstream
limit of
Mary
Barrage
pondage
to Mary
River
Tagigan
Road to
upstream
limit of
Tallegalla
Weir
pondage
Tallegalla
Weir
pondage
M39
no sites surveyed
M40
site 32 at Blowers Road single representative rainforested site;
mesic species such as
W. floribunda & Acmena hemilampra dominant & abundant
respectively; lantana is frequent in distal parts of this
community which was assessed largely to be in very good
condition.
bars drowned by weir; single site (at the Myrtle Creek
confluence – i.e. site 28) considered representative of this
stream; note rheophyte zone was absent, having been lost with
bank slumping & rip. verge currently upslope community with
dominant E. tereticornis, Guoia semiglauca, *Psidium
guajava, Melaleuca bracteata, Aphananthe, *Celtis
paniculata; weeds prevalent; condition rated as moderate.
rainforest canopy stream; single site (at Tagigan Road – site
40) checked; rip. verge in moderate–good condition (apart
from woody weeds); dominants are W. floribunda, *Celtis
paniculata, *Cinnamomum camphora; other weeds (especially
lantana) prevalent; while structurally intact, highly modified
floristically.
Tallegalla
Weir to
upstream
limit of
Teddingto
n Weir
pondage
Teddingto
n Weir
pondage
M44
Myrtle
Creek
Tinana
Creek
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
River/
Stream
M41
M42
M43
M45
bars drowned by weir; single site (upstream of weir wall – site
24) checked; rip. verge in very good condition; dominants
comprise Casuarina glauca, Tristaniopsis laurina, Melaleuca
styphelioides & * Mangifera indica; major weed present is
*Leucaena leucocephala: here the riparian community is
structurally intact and appears to have adjusted up-bank to
elevated water levels.
two sites (downstream of weir wall – site 25 & Tuan Forest
Crossing – site 26) checked; rip. verge largely in intact
condition; dominants include Tristaniopsis laurina,
Waterhousea, Acacia melanoxylon, A, falcata, Lophostemon
suaveolens; weeds (e.g. wildings of the timber tree *Pinus
elliottii) occasional.
lower part of riparian zone drowned by weir; single site (site
21) checked; dominated by Casuarina glauca,, Acacia cf
sophorae, Corymbia intermedia; para grass prevalent about
weir pool as are exotic aquatic macrophytes; assessed to be in
moderate condition
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River/
Stream
Reach
Name
Teddingto
n Weir to
Tinana
Barrage
Reach
No.
Site Descriptions and Comments (refer to Figure.1 for reach
locations)
M46
bars and lower part of riparian zone drowned by weir, gaps in
riparian zone;
two sites (downstream of weir wall – site 22 & upstream of
wall - site 23) checked; rip. verge dominants include
Callistemon viminalis, *Leucaena leucocephala,, Tristaniopsis
laurina, Lophostemon suaveolens (22) and C. viminalis,
Acacia melanoxylon, Melaleuca styphelioides with para grass
at 23; condition assessed as good to very good respectively.
Cane farming and other agricultural activities also have repercussions with regard to the
nutrient status of the riparian zone and for the streams themselves. Fertilisers and pesticides
drain downslope from agricultural areas into the riparian zone and into waterways and
waterbodies. This can, in the case of the toxic herbicides, cause direct damage to riparian
plants, either through direct death or sub-lethal effects including the induction of “bunchytop” symptoms that may reduce vigour to a point where plants become out-competed by
exotics or fail to reproduce successfully. The leaching of nutrients applied to crops as
fertilisers can, in the context of the comparatively poor soils of the district, not only advantage
exotic species not pre-adapted to low nutrient situations, but also can cause eutrophic
conditions along stream verges and within waterways. This frequently prompts vigorous
growth of moisture-loving terrestrial plants and/or incursion into riparian communities of
semi-aquatic grasses.
It is evident that (i) extensive clearing of the catchment and of the riparian verge itself for
agriculture and pastoralism, (ii) the direct and indirect impacts of agricultural fertilisers and
pesticides, as well as those of grazing stock, and (iii) the direct and indirect impacts of exotic
plant introductions have caused major transformations in the nature and functioning of
vegetation along the district’s waterways and wetlands. This is particularly evident along the
upper reaches between Maleny and Kenilworth and along the middle reaches of the Mary and
its major tributaries (especially Widgee, Kandanga Creek and, to a lesser extent, Amamoor
Creek) between Imbil and Tiaro (O’Donnell 2001:Fig. 5.5).
The condition of the riparian zone is also influenced by a phenomenon that has arisen due to a
combination of factors, not the least of which has been the significant reduction in the area of
native vegetation. This is commonly referred to as “die-back”. Mature riparian trees,
including both she-oaks and eucalypts, are susceptible. The extent of this pathology has been
documented for the southern half of the State (Wylie et al., 1992) and more intensively for the
Mary River catchment in particular (Wylie et al., 1993). The Mary River study demonstrated
the high level of interaction between tree clearing and land use in different parts of the
catchment, levels of streamwater salinity and insect (particularly Rhyparida libatipennis
beetles) attack and riparian tree condition. Again, dieback appeared most severe along the
middle reaches of the Mary and along major tributaries such as Widgee Creek (Wylie et al.
1993).
5.2.2.
Impact of factors associated with water resource development.
A stream’s flow regime is the primary determinant of how it functions and the extent of
interaction and transfer of materials between the riverine environment and adjacent
ecosystems (Sparks, 1992). Alterations in the amounts and temporal patterns of discharge
delivery, therefore, have the potential to impact upon many ecological components of the
riverine and near-stream environments.
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Reduction of flows within streams can be expected to lead to several responses within the
near-stream vegetation. Firstly there will be a trend to a readjustment of vegetation zonation
about the channel with a downslope migration of hygrophilic (moisture-loving) plants such as
the reophytes (fast flow-adapted species) and those characterising the immediate upslope
fringe to occupy a contracted channel. Ecesis or successful establishment of these plants may
be impaired by the exposure of bedrock or bed armouring associated with clearwater
(sediment-starved) erosion immediately below large dams or weirs and scouring during peak
discharge events. Secondly, and not necessarily unrelated to those processes inhibiting
riparian readjustment, there is likely to be a narrowing of the riparian verge and a
corresponding expansion of upslope communities unrelated to streams that will occupy areas
along streams formerly supporting the riparian community. Thirdly, reduction in available
moisture and the wetted perimeter of the stream may lead to reduced vigour that may result in
structural changes such as reduction in community height, greater canopy openness and
consequent shifts in the relative representation of subordinate strata such as sub-canopy,
understorey and groundcover layers. Lastly, it can be expected that there may be floristic
shifts within the near-stream community – i.e. from the mesic (those favouring moist
conditions) to the xeric (drought-tolerant) – with a reduction in moisture availability about the
stream verge.
In most Australian contexts, including within the Mary system, these shifts will be associated
with increased fire-proneness and possibly increased vulnerability to exotic species invasions.
This, in turn, may constitute a factor reinforcement process that can lead to the collapse and
demise of local riparian systems. This is evident along some reaches of the system.
In contrast to situations where flows are reduced through impoundment and abstraction, flow
supplementation can occur in streams used to deliver water for use in other parts of the
landscape. Greater flows are experienced in smaller perennial streams and, in many cases,
intermittent streams become perennial and ephemeral streams intermittent. Since channel
form is a direct function of discharge, morphological adjustments will occur with direct
implications for fringing vegetation.
In such cases, increases in available surface water/wetted perimeter has prompted increased
growth of mesic plants, possibly at the expense of more xeric local species. Additional
moisture availability may also promote increased vigour and height of the fringing vegetation.
This scenario can also initiate interaction with factors unrelated to water resource
development by increasing the opportunity for invasion of exotic species that require more
moist conditions than normally occur at a particular site. These include a suite of introduced
pasture species such as Guinea Grass (Panicum maximum) that cure during the drier times of
the year to produce highly flammable fuel loads, increasing the fire-proneness of the nearstream community (Wallmer 1994).
Should flows be elevated to levels that will inundate lateral terraces, opportunities for the
invasion of exotic ponded pasture species such as Pará grass will be greatly increased. This
will have implications for existing aquatic assemblages since these grasses, because of their
intrinsic photosynthetic systems, do not contribute carbon to the food chain (Bunn et al.
1997).
The above are relatively subtle, although not benign, impacts. In some instances
impoundments or in-stream storages have resulted in the inundation and direct destruction of
riparian systems, as in the case of all three major weirs. Dead spars of formerly middle-bank
riparian trees are testimony to water resource development impacts. These are particularly
prominent in Teddington Weir and in sections of the larger impoundments such as Baroon
Pocket and Borumba Dams. Where trees have been drowned and the canopy consequently
opened, exotic weed species have proliferated, adding a factor reinforcement dimension to the
direct impact of impoundment.
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With stream regulation, it is likely that the riparian system will not be exposed to high flows
of low to intermediate periodicity. Instead, trees may re-establish and develop within a
disturbed riparian zone in the absence of high flows until such a time when a major spate
scours or damages them severely. While these are zones of natural disturbance, evidence for
this exists where there are even aged stems of river oak and/or paperbark reflecting
preferential establishment phases without scouring, and by other stands where severe damage
has been sustained. Damage is in the form of broken boles, multiple-stems, uprooting and
downstream deflection of stem growth. Crowns exhibit branch death, leaf abscission,
necrosis and generally poor form.
Other components of water resource development that further disrupt the riparian zone can be
a little more difficult to distinguish from the myriad of factors exerting influence on that zone.
These can operate indirectly and/or reinforce or countervail other factors that are operating.
For instance, the greatest impacts beyond those associated with impoundment, inundation and
death of the riparian verge are likely associated with supplementation and disturbances
relating to fluctuations in water levels that advantage the exotic species that have already been
introduced to the system. Fluctuating water levels are particularly advantageous to the ingress
of ruderal and/or annual species (especially exotic members of the daisy family). Hence there
can be both floristic and structural changes within the riparian zone as a result of
combinations or mixtures of influences that are difficult to extricate.
While symptoms of such impacts (e.g. riparian inundation, vegetation encroachment with
reduced flows and riparian readjustment to elevated stream levels) are evident at various sites
throughout the catchment, the intensity and extent of impacts arising from non water resource
uses vastly override any impacts observed. Not only has the riparian verge been destroyed
and greatly disrupted by direct physical means, indirectly is has suffered from exotic weed
invasion. Moreover, streams within the Mary system appears to exhibit ongoing decline
associated with a factor interaction process where clearing and land use pressures have
interacted with water table salinity to render constituent trees susceptible to insect attack,
stress and die-back. While indicative of the complexity of a situation within which various
factors interact to reinforce, accelerate and amplify impacts, other factors have certainly
eclipsed any impacts readily attributable to water resource developments.
6.
NEED FOR FURTHER RESEARCH AND MONITORING.
This section is divided into two parts. The first includes consideration of research that is
required in order to provide a better understanding of environmental flow requirements,
particularly with respect to riparian vegetation and its attendant fauna, in the study area. The
second comprises components of a recommended monitoring framework for determining the
environmental effects of WRP strategies.
6.1.
Research Needs.
This report has been developed using currently available information and experience.
However, the assessment of the environmental flow requirements of river systems is a new
and developing area of science. Over time, ongoing research in this area will lead to better
understanding of the geomorphological and ecological processes in rivers and streams in the
study area, and their relationships to flow regimes. Priority research areas are identified
below.
Firstly, there is a pressing need to determine the linkage between riparian vegetation and
stream flows along upper, middle and lower reaches of major streams in the various
bioregions. The degree of dependence of riparian communities on surface water drainage
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within waterways, their response to water level fluctuations and departures to the normal
seasonality of flows should be more confidently determined.
While some such questions are being addressed by current studies there is an urgent need for
more intensive research in these areas. Community physiological studies that may determine
water use, and by implication, water requirements, are sorely needed to add some measure of
confidence to predictions that are, to date, based on ‘best professional judgement’, inference
and experience of comparable systems.
There is also a need for improved understanding of the role of shallow alluvial aquifers in the
structure and functioning of riparian zones, and the role of flows in maintaining and
recharging such aquifers. It is important to ascertain those relationships and to determine the
role of flows in maintaining and recharging shallow alluvial aquifers that are found to be
important for riparian vegetation in the catchment.
More explicit documentation of the floristic and structural variation of riparian vegetation
communities within the different parts of the catchment’s landscape is also required to add
precision to determinations of existing impacts, trends and predictions for change. This is
particularly so given (i) the often highly residual nature of riparian vegetation in greatly
transformed catchments, combined with (ii) the frequency of rare and/or threatened plants that
are naturally rheophytic (e.g. Xanthostemon oppositifolius) or now largely confined to nearstream occurrences because of the destruction of upslope communities. There should be a
temporal as well as a spatial dimension to the research design of dedicated studies in this
regard.
Determinations also might be better informed if there was more substantive hydraulic
information for representative sites. Transverse transects of the riparian vegetation could then
be related directly to channel morphology and water levels to inform understandings of flow
tolerances, vegetative responses and community zonation. The monitoring of associated
permanent plots, thereafter, would produce explicit outcomes regarding the relationships
between riparian vegetation and flow regimes. Experimental releases from storages may be
required to examine impacts associated with the full range of flow regimes.
6.2.
Monitoring Requirements.
It is evident that there is a growing need to establish and monitor near-stream (and in-stream)
vegetation change. This can be undertaken by regularly surveying strategically selected
representative permanent plots adjacent to streams – preferably on both banks - to ascertain
the nature and extent of vegetation change. Given the existence of local hydraulic data and
knowledge of the flow regime, qualitative measures of the nature and degree of impact
established with greater confidence and quantitative relationships between stream flow and
vegetation trends may become apparent.
7.
SUMMARY AND CONCLUSIONS.
An assessment of the condition of riparian vegetation was undertaken as part of the Mary
WRP process. The study area covers the Mary River Catchment and neighbouring
catchments of the Burrum River and Beelbi Creek. Assessment was based on a limited field
visit undertaken TAP members. It was greatly augmented and extended by work undertaken
by Johnson (1997), complemented with aerial photographic interpretation.
The purpose of this assessment was attempt to determine impacts associated with water
resource developments from the range of factors impinging on riparian vegetation. This was
with the view to determining limits of acceptable change so as to uphold the principle of
ecological sustainability. A secondary purpose was to bring into consideration other features
Australian Centre for Tropical Freshwater Research
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at risk within the landscape, not the least being rare and/or threatened regional ecosystems
(REs), plants and animals, and their habitat, landscape integrity and connectivity and various
attributes that confer significance to sites within the study area. In that regard, riparian
communities and associated wetlands were seen to be vital landscape components,
contributing much in terms of faunal and floral habitat, protecting and sustaining waterways
and waterbodies and providing wildlife corridors to link remnant vegetation. This
contribution is disproportionately great when compared to the area of the landscape that is
occupied by these communities, especially given the extent of clearing experienced by the
catchment.
Several REs that are classified formally as rare/threatened occur within the Mary WRP study
area. Of these the ‘endangered’ regional ecosystem 12.3.1 (Gallery rainforest on alluvial
plains) is the one most clearly associated with the catchment’s streams. This RE is also
important as habitat for flora and fauna species of particular conservation interest.
Another ‘endangered’ RE is 12.3.3 - Eucalyptus tereticornis tall open forest on alluvial plains
and associated lower slopes. It appears to be restricted to about Kilkivan along Wide Bay
Creek and its tributaries and again along the middle reaches of Doogul Creek in the Burrum
River catchment. The linear configuration of this vegetation type demonstrates its close
association with streams. Owing to its highly residual nature, the fact that it is mostly
unconserved and the degree of disturbance evident within the small areas that do remain
(Young and Dillewaard 1999:12/16), it is of importance to ensure that water resource
development does not further contribute to endangering processes.
The highly degraded condition of she oak-dominated riparian zone of the Mary River may
suggest that this forest type constitutes a hitherto undocumented RE that might also be listed
as ‘endangered’ and worthy of increased protection.
It was estimated that some 55 plant taxa comprising nine endangered species, 22 vulnerable
species and 24 others listed as rare/restricted are recorded from, or considered likely to occur
in, the Mary Catchment and neighbouring catchments. It is evident that both water resource
development (particularly that associated with the flooding of riparian systems upstream of
major impoundments on the Mary) and external factors such as extensive clearing for
agriculture have already impacted on species. Two-thirds of these are known to occur within
or can be considered likely to be associated with streams and wetlands of the study area. This
is particularly so in the case of listed species – e.g. X. oppositifolius - occurring within the
gallery rainforest (12.3.1) discussed above and in RE12.9/10.16. Other notable rare and/or
threatened plants associated with riparian systems include the endangered mintbush,
Plectranthus torrenticola, the rare/restricted paperbark of seasonal wetlands, (Melaleuca
cheeli) and wattle (Acacia perangusta) of Beelbi Creek catchment.
A sizeable proportion of the district’s flora comprises exotic weed species – particularly
exotic pasture grasses and stock forage legumes. The most prevalent infestations in the
catchment include those of Chinese elm, privet, lantana, cat’s-claw creeper and, another vine,
Anredera cordifolia, Japanese Sunflower and grasses such as Guinea grass and grader grass.
Disruption of the riparian zone, along with supplementation and increased reliability of
stream flows associated with stream regulation has greatly advantaged the spread of these
weeds.
The condition of the riparian zone along the major trunk streams of the study area varies
greatly. It ranges from near natural in the upper catchment to greatly disrupted or nonexistent, as along the middle and lower reaches of the Mary River. Overall, degradation has
been moderate to severe.
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Apart from the direct impacts of the in-stream storages associated with major dams and weirs,
factors other than those directly associated with water resource development impact in a far
greater way on the condition of riparian systems. Impoundments have resulted in the death of
streamside trees, the up-bank migration of a degraded riparian zone and the proliferation of
weed species.
Elsewhere clearing for access routes and utility corridors and for additional agricultural land
has had major impacts on the structural and floristic integrity of the riparian zone. Weed
incursions are particularly prevalent where physical disruption has been the most intense. As
a result, communities along streams are less viable in the medium to long term as xeric
species and various alien species have replaced the more mesic native assemblage (with the
added risk of catastrophic fire damage) and there is a suite of ongoing stresses to existing
trees that are amplifying the decline.
Since riparian and wetland communities have such a vital habitat function for a highly
significant proportion of any given district’s fauna, it is expected that several rare and/or
threatened animal species may be at risk from activities impacting adversely on these
communities. The foremost of these is the endemic Mary River turtle. Rare and endangered
frog species are also associated with fast-flowing (lotic) streams, however, these are located at
higher altitudes and largely unaffected by water resource developments. Another suite of
threatened frogs is associated with the acid wallum wetlands of the lower catchment and may
be susceptible to impacts associated with water resource development within the lower
catchment.
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