Contemporary and Historical Descriptions of the Vegetation of Brundee and Saltwater Swamps on the Lower Shoalhaven River Floodplain, Southeastern Australia

2007·12.2 MB·English

by  David A Keith

Contemporary and Historical Descriptions of the Vegetation of
Brundee and Saltwater Swamps on the Lower Shoalhaven River
Floodplain, Southeastern Australia
David A. Keith, Christopher Simpson, Mark G. Tozer and Suzette Rodoreda
Biodiversity Conservation Science, NSW Department ofEnvironment and Conservation, PO Box 1967
NSW
Hurstville 2220
Keith, D.A., Simpson, C, Tozer, M. G. and Rodoreda, S. (2007). Contemporaryandhistorical
descriptions ofthe vegetation ofBrundee and Saltwater Swamps on the lower Shoalhaven River
floodplain, southeasternAustralia. Proceedings oftheLinneanSocietyofNewSouth Wales 128, 123-
153.
CoastalfloodplainsarefunctionallyimportantandhighlyendangeredecosystemsinsoutheasternAustralia,
which have a long history ofexploitation and environmental modification. In this study, we undertook a
systematic surveyofcontemporaryvegetationintworecentlyestablishednaturereservesonthesouthcoast
ofNew South Wales and investigated historical records ofthe vegetation and environment to infer likely
changes since European settlement.Ananalysis offloristic samples showedthatthepresent-dayfloodplain
vegetationincludesamosaic ofwoodlands, forestsandsaltmarsh/reedland(five communities)thatcontrast
markedly in species composition and structure to eucalypt forests that occupy the surrounding hills (two
communities). One hundred and forty-nine plant species were recorded in 24 0.04 ha samples within the
reserves, with Poacaeae and Cyperaceae represented by the most species on the floodplain. Some parts of
the floodplain contain substantial weed infestations, while other parts ofthe floodplain are largely free of
weeds. The vegetation underwent a series ofchanges since the firstrecorded observations in 1805. Atthat
time the floodplain included a mosaic ofwoodland, grassland and reedland. Native grasslandnow appears
to be extinct as aresultofsubsequent clearing, intensive cattle grazing, pasture improvement and changes
A
to drainage. network ofdrains, initially constructed around 1900 and further developed in the 1960s,
resulted in soil oxidation. This may have made the floodplain soils more suitable forwoody plant species,
but recruitment has been largely prevented by intensive cattle grazing. A recent expansion of Casuarina
and Melaleuca scrub and forest is evident within the nature reserves since their dedication and exclusion
oflivestockin2001,butnoton adjoiningpropertieswhere intensive cattle grazing continues. We conclude
thatthereserves include importantsamples ofremnantfloodplainvegetationandthatthevegetationis in a
continuing state offluxregulatedby changing flood andtidalregimes andgrazingregimes.
Manuscriptreceived 1 November2006, accepted forpublication 15 January2007.
KEYWORDS; coastal wetlands. EndangeredEcological Communities, European impact, floodplain,
Shoalhaven River, vegetation change, vegetation classification, vegetation history.
INTRODUCTION landscapes.Theseprocessesincludeclearingofnative
vegetation, intensive grazing by domestic cattle,
Coastal wetlands are fiinctionally important pastureimprovementandcultivation,changestowater
ecosystems. They are significant carbon sinks, regimes (watertable depth, floods, tides), particularly
resource-rich repositories of moisture and nutrients, through construction of drains and tidal gates,
habitats forhighlyspecialisedplantlife andimportant changes in soil chemistryandstructure, andinvasions
breeding grounds for wetland-dependent fauna ofalien plant and animal species. Collectively, these
including birds, firogs, fish, Crustacea, molluscs and processes have had a range of adverse impacts on
the ecological functions offloodplains. For example,
other invertebrates.
Coastal floodplains are perhaps the most coastalfloodplainsoilsoftenhavehighconcentrations
endangered and heavily modified ecosystems in of sulfur, which accumulated during the deposition
southeastern Australia (Keith 2004, Keith and Scott of marine sediments in the early stage offloodplain
2005). The present status and parlous future ofthese development. Drainage works or other earthworks in
remnantsisrecognisedinthelistingofsixEndangered the swamps, exposetheirsoils to oxidation, liberating
Ecological Communities under the Threatened sulphuric acid into the soil solution (Johnston et al.
Species ConservationAct(1995) inNewSouthWales. 2003). As well as being toxic to plants and animals,
Complex interactions between multiple processes sulphuric acid leaches minerals that would otherwise
has transformed temperate coastal floodplains be fixed in the soil, including iron, aluminium and
from natural systems to intensely managed human magnesium. Thus, rapid drainage of swamps after
VEGETATION OF BRUNDEE AND SALTWATER SWAMPS
rainfall can cause high concentrations of acid and Swamp covers an area of approximately 600 ha, of
dissolved metal ions in drains and estuaries, killing which 230 ha are included within the nature reserve.
fish and other animals dependent on the estuaries. Saltwater Swamp covers approximately 480 ha, of
The decline of aquatic life in acid-affected swamps which 215 ha are included within the nature reserve.
also has impacts on the use of these areas by other The two nature reserves are separated by a distance
water-dependent fauna, including waterbirds. ofabout 1 km, comprising partially cleared freehold
Despite the intensity of past and present land land, which occupies a low rise above the floodplain.
uses, many of the coastal floodplains still support To the south and west ofthe reserves, the floodplain
fragments of native vegetation, albeit in a highly rises gradually into low forested hills ofsiltstone and
modified form (Keith 2004). These are maintained sandstone,whicharepartlyfreeholdandpartlywithin
in a state of flux in response to continuing changes Currambene State Forest.
in land use, particularly water management, grazing Brundee and Saltwater Swamps are large, low-
and cropping. Under the influences ofglobal climate lying, shallow, fresh to brackish wetlands mostly
change, the remaining native vegetation is likely to at or below Mean Sea Level (±1.0 m). Some small
become even less stable in the future. Vegetation areas are inundated semi-permanently, while large
changes have profound effects on the ecological areas of both swamps are inundated periodically
functions of the floodplains. For example, projected and are without surface water for most of the time
increases in atmospheric CO concentrations, rising (Dalmazzo et al. 2000). Each swamp has a small
temperatures and projected declines in precipitation catchment ofless than 2 000- 3 000 ha. The swamps
and flood fi-equency are predicted to accelerate the apparently formedas aresult ofdeposition ofmarine,
release of carbon from wetland sediments (Gorham estuarine and fluvial sediments, which infilled old
1991,Freemanetal. 2004)anddrivestructuralchange coastal lagoons as sealevels rose atthe endofthe last
in habitats ofspecialised organisms (Hughes 2003). glaciation (Dalmazzo et al. 2000).
At present, the mechanisms that regulate the
direction and rates of vegetation change on coastal Field Sampling
floodplains are poorly understood. The experimental Floristic composition and vegetation
studies needed to elucidate these mechanisms structurewere sampled at 21 sites within the Brundee
require baseline data as context for interpreting and Saltwater Swamp nature reserves. In addition,
fixture responses to environmental change. While four samples were obtained from a previous survey
comprehensive surveys have been carried out in project (Tindall et al. 2004), including three within
wetlands on some subtropical latitudes (Pressey the reserves and one nearby. The sites were located
1989a, b, Pressey and Griffith 1992), floodplains of to cover a range of landforms, structural forms and
more temperate latitudes have been comparatively geographic locations within the study area including
neglected. On the Shoalhaven River floodplain forest, scrub and sedgelands onthe floodplain, forests
120 km south of Sydney, conservation reserves have on the margins ofthe floodplain, and forests on low
been established on parts oftwo floodplain wetlands, hills and slopes above the floodplain.
which provide important reference areas for research Fieldworkwas carriedoutduring 16-17 February
on wetland dynamics in response to changes in both 2006. Vegetation sampling methods were identical to
climate and land use. The aims of this study were those used by Tindall et al. (2004) and Gellie (2005).
to describe and map present-day vegetation of the A global positioning system was used to record
reservesbygatheringbaseline datafromthefield, and the location and elevation of each survey site Tape
to describe past states ofthe vegetation by reviewing measures were used to mark out survey quadrats of
historical information from the recent past and early 0.04 ha. These quadrats were square (20 x 20 m),
European times. except where different dimensions were required
to ensure that landform and soils were reasonably
homogeneous within the plot (for example an 8 x 50
METHODS m quadrat was used along a drainage feature).
All vascular plant species rooted within or
Study area overhanging the quadrat were recorded and assigned
Brundee Swamp and Saltwater Swamp are a cover/abundance score using a modified Braun
located about 7 km south-east of Nowra (latitude - Blanquet scale (Poore 1955) as follows: 1- Rare,
34°55'S, longitude 150°39'E) on the edge of the one or few individuals present and cover < 5%; 2-
broad, lowland floodplain of the Crookhaven River. uncommon and cover < 5%; 3- common and cover <
Brundee Swamp is on the upper floodplain of the 5%; 4- very abundant and cover < 5% or 5% < cover
Crookhaven River, which subsequently runs through <20%; 5- 20% < cover<50%; 6- 50% <cover<75%;
Saltwater Swamp before entering the ocean close 7- 75% < cover< 100%.
to the mouth ofthe Shoalhaven River. The northern The height range and projected foliage cover
parts ofBrundee and Saltwater Swamps are freehold were estimated for all vegetation strata recognisable
land and have been used for grazing and associated at the site (e.g. tree, small free, shrub, groundcover).
cropping for many years (Dalmazzo et al. 2000). Atthecenfre ofthequadrat, acompass andclinometer
Nature reserves were established in southern parts of were used to measure the slope, aspect and horizon
the two swamps in January 2001 on former Crown elevations at compassbearings of0, 45, 90, 135, 180,
land that was subject to permissive occupancies for 225, 270 and 315°. Soils were examined by hand-
cattle grazing by adjoining landholders. Brundee texturing andnotes made on colour, texture, moisture
124 Proc. Linn. Soc. N.S.W., 128, 2007
.
D.A. KEITH, C. SIMPSON, M.G. TOZERAND S. RODOREDA
content and depth. Evidence of outcropping rock, samples compiled by Tindall et al. (2004) from the
erosion, weed invasion, logging, soil disturbance or lower Shoalhaven district. This larger data set was
recentfire was noted. analysed using the same methods as those described
All native and exotic vascular plant above. The correspondence between the site groups
species were recorded. Plant species that could not for Bmndee and Saltwater Swamps and existing
be identified in the field were collected for later communities defined by Tindall et al. (2004) was
identification. Where necessary, collections were sent assessed by cross-referencing group membership for
for identification to the National Herbarium ofNSW. the sitesbetweenthetwo classifications. This allowed
Nomenclature was standardised to follow Harden each new site from Bmndee and Saltwater Swamps
(1990 - 2002) and Flora Online (http://plantnet. to be assigned to one of the P5MA communities.
rbgsyd.gov.au). These interpretations were verified by assessing the
To allow for ongoing monitoring of the plots, species list for each site against the list ofdiagnostic
a steel star post marked with a fluorescent green species for the corresponding community described
top and a uniquely numbered stainless steel tag was by Tindall et al. (2004).
located at the north eastern comer ofeach quadrat. A
photopoint was established at each site framing the Map preparation
comer post from a bearing that was recorded on the Existing vegetation boundaries on the P5MA
fielddatasheet.Anindicativeassessmentoffuelloads vegetation map (Tindall et al. 2004) were updated
was made at each site based on the method for fine by stereoscopic aerial photo interpretation (API) of
fuels and total fiiel load described in the Department colour photography 1:15 000 scale flown in January
of Environment and Conservation's Incident Field 1996. Boundaries were further adjusted on-screen
Handbook (pp 24 - 25). using an orthorectified digital aerial photograph
To assess spatial variation in growth stages flown in 2001. The photography was interpreted to
within each woody vegetation type, the angle count delineate all patches ofnative vegetation larger than
(Bitterlich) method was used to estimate stand basal one hectare in size. In some cases, it was possible to
area at each quadrat. The Bitterlich method uses an map additional patches that were smaller than one
m mm
angle gauge, a stick 1 in length with a 20 hectare. Woody vegetation was mapped where crown
cross piece at one end, to assess all the trees around cover was > 5%. Interpretation of boundaries was
a central sampling point (Mueller-Dombois and informed by location of sample sites and additional
Ellenberg 1974; Carron 1968). The operator stands at fieldrecormaissance.
the sampling point, sights along the stick to the cross
piece at the far end, and counts the number oftrees Vegetation and management history
with diameteratbreastheight largerthan, or equal to, We reviewed evidence of changes to the local
the angle indicated by the cross-piece. Counts were floodplain environment and its vegetation from
tallied by assigning a fiall point to trees larger than a number of different sources. These included
the cross piece and a halfpoint score to trees equal surveyors's maps and reports for the Shoalhaven
mm
to the cross piece. With a 20 cross piece on a floodplain from the Land Property Information
m
stick of 1 (ie a ratio of 1:50), the Bitterlich count Service; historicalarticles; reportsandjoumal articles
approximates the basal area of trees in the stand in onlocalenvirormientalstudies;andaerialphotographs
square metres per hectare. of the Bmndee and Saltwater Swamps flown at
two recent dates (1996 and 2001). We interpreted
Data analysis and description ofPlant information from these sources to reconstmct likely
Communities characteristics of historical water regimes, soils and
A
multivariate analysis of native species vegetation ofthe local floodplain.
composition data from the plots was carried out to
develop a classification ofplant communities in the
two reserves. A data matrix was first assembled fi"om RESULTS
all available data, including the 21 plots recorded in
this survey and four plots recorded previously in and Vegetation Classification
P5MA
aroundthe reserves during the survey (Tindall The 25 vegetation samples were classified into
et al. 2004). All exotic species were excluded from seven groups on the basis of similarities in species
the data matrix so that the classification was based composition (Fig. 1). Each oftheseplantassemblages
on native species composition. Specimens that could was referrable to communities described previously
not be identified to species level were also omitted by Tindall et al. (2004). Eucalypt-dominated
fromthe analysis. Compositionaldissimilarity among communities were segregated in the dendrogram
sampleswascomputedonunstandardiseddatausinga from the remainder of the samples. Eucalypts were
symmetric formofthe Kulczynski coefficient (Belbin generally confined to the margins of the floodplain
1994). Hierarchical agglomerative clustering was and the surrounding hills, while the floodplain itself
carried out using a flexible unweighted pair group was characterised by a mosaic of forested wetlands
arithmetic averaging strategy with no adjacency dominated by non-eucalypt tree genera and treeless
constraint and B = -0.1 wetlands.
To assist interpretation ofsite groupings defined
in the cluster analysis, the 25 samples from Bmndee Description ofPlant Communities
and Saltwater Swamps were added to a larger set of A local synopsis of the seven communities for
Proc. Linn. Soc. N.S.W., 128, 2007 125
({((((
VEGETATION OF BRUNDEE AND SALTWATER SWAMPS
0.2610 0.4548 0.6486 0.8424 1.0362 1.2300
1 1 1 1 1 1
pl07 BrunOl 1)
pl07 BrunOS S)
_ 1
pl07 NOW011A( 13)
1 1
pl05 Brun02 2)
(
pl05 NOW004A( 10)
1
pl05 Salt06( 19)
1 1
pl05 SaltOl 14)
( 1
pl05 Salt03( 16)
_ 1
pl05 Salt04( 17)
1
pl06 Brun08 8)
pl06 SaltOS 21)
( 1
pl06 Brun09( 9)
1
pl06 Salt07( 20)
1 i
p509 Brun03 3)
1
p509 Salt02( 15)
1
p509 SaltOS 18)
( 1 1
p509 NOWOIOAC 12)
1
p85 Brun04 4)
p85 SaltlO( 23)
_ 1
p85 Saltl5( 25) 1 "
p99 Brun07 7)
p45 Brun06( 6)
1
p45 NOW005A( 11)
p45 SaltlK 24) 1 1
1 1 1
p45 Salt09( 22)
1 1 1
0.26110 0.45148 0.64186 0.84124 1.03162 1.2300
Figure 1. Dendrogram showing tlie compositional relationsliips of25 vegetation samples and the plant
community to which each sample was allocated (left-hand column). Scales at the top and bottom ofthe
dendrogram show Kulzcynski ultra-metric dissimilarity values.
Brundee and Saltwater Swamp Nature Reserves is Biodiversity ConservationAct1999(EPBCAct 1999)
given below. Their mapped distributions are shown occur in the reserves.
in Fig. 2. The most extensive communities within the
reserves are Estuarine Fringe Forest and Floodplain Floodplain Swamp Forest (FOWpi05)
Swamp Forest, with Estuarine Creekflat Scrub and Floodplain Swamp Forest (Fig. 3) within the
Currambene Lowland Forest the next most abundant reserves is characterised by a typically dense to open
communities (Table 1). The other three communities canopy dominated by Casuarina glauca with trees
are not common within the reserves. oMr shrubs of Melaleuca ericifolia (or occasionally
Tozer et al. (2006) provide more general styphelioides) in comparatively lower abundance.
descriptions for each of the seven mapped The understorey generally lacks woody plants other
communities across a larger region between Sydney thansparsejuvenileindividuals ofthe canopyspecies.
and the Victorian border. The codes for each map Vines of Parsonsia straminea occur occasionally,
unit follow those of Tozer et al. (2006), in which eitherasscramblersatgroundlevelorascendingstems
capital letters represent abbreviations of structural ofcanopy trees. The groundcover comprises an open
formations describedbyKeith (2004). These include: coverofsedges,grassesandforbs,mchxdmgEntolasia
FOW Forested Wetlands; SL Saline Wetlands, DSF marginata, Juncus kraussi subsp. australasicus,
Dry Sclerophyll Forests, and WSF Wet Sclerophyll Carex appressa and Cyperus polystachyos, with
Forests. Commelina cyanea. Lobelia anceps, Alternanthera
As of 31 December 2005, three Endangered denticulata and Senecio hispidulus var. hispidulus,
Ecological Communities (EECs) listed under the which are dispersedwithin a dense cover ofleaflitter
NSW
Threatened Species Conservation Act (TSC from the canopy. Patches of Phragmites austrails
Act 1995) occur in Brundee Swamp and Saltwater may occur inthe understorey where the watertable is
SwampNRs. The inferredrelationshipsbetweeneach more frequently close to the surface (Fig. 4).
of these EECs and the plant communities described Floodplain Swamp Forest has been recorded
and mapped below are given in Table 2. A fourth and mapped primarily around the eastern and
EEC, Freshwater Wetlands on Coastal Floodplains western margins of Brundee Swamp (from which
of the NSW North Coast, Sydney Basin and one site was recorded - Brun02) and a large patch
Southeast Comerbioregions, occurs nearbybut is not covering the central and easternportions ofSaltwater
currently mapped within the reserves. No ecological Swamp (from which the remaining five sites were
communities currently listed as Endangered under recorded). These are raised areas of the floodplain
the Commonwealth's Environment Protection and that are likelyto experience lowerlevels ofsalinity in
126 Proc. Linn. Soc. N.S.W, 128, 2007
D.A. KEITH, C. SIMPSON, M.G. TOZERAND S. RODOREDA
Road
IZjdecEstate
Srtes
33^.DSFp85CurrambeneLowlandFofesl
^HFOWpi05FloodplainSwampForest
FOWp106EsluarlneFringeForest
[m• FOWpi06aEstuarineFringeFwest
FOWp107EstuarineCreekflatScrub
S=^FOWp45CoastalSandSwampForest
IHiGWp3SoutliCoastLowiandSwamp
Woodland
>ffi9SLp109EstuarineMangroveFocest
BH
SLP&09EstuarineSaltmarsh
WSFpSSlllawarraGuilyWetFoiast
Cleared
o
1Kilometre
Figure 2. Vegetation map ofBrundee Swamp, Saltwater Swamp and surrounding areas.
Table 1. Estimated areas ofplant communities within Brundee Swamp NR and Saltwater Swamp NR.
Estimated area in Estimated area in
Community Brundee Swamp NR Saltwater Swamp NR Total
(ha)
(ha) (ha)
Floodplain Swamp Forest (FOW pi05) 16.4 98.4 114.8
(FOW
Estuarine Fringe Forest pi06) 49.8 46.9 96.8
Estuarine Fringe Forest regenerating
119.0 119.0
(FOW
pi06a)
Estuarine Creekflat Scrub (FOWpi07) 32.9 9.1 41.9
Estuarine Saltmarsh (SLp509) 2.1 9.2 11.3
Coastal Sand Swamp Forest (FOWp45) 1.6 8.6 10.2
Currambene Lowland Forest (DSF p85) 1.2 41.5 42.8
Illawarra Gully Wet Forest (WSF p99) 4.4 4.4
Water 0.5 0.5
Total 227.3 214.2 441.5
their groundwater than stands of Estuarine Fringe depressions with more saline influence may support
Forest (FOW pi06), which occur on lower parts (unmapped) patches ofFOWpi06.
of the floodplain and in local depressions. Much of
the eastern two-thirds of Saltwater Swamp NR has Estuarine Fringe Forest (FOWpi06)
FOW
been mapped as pi05. Within this area, small Estuarine Fringe Forest (Fig. 5) within the
Proc. Linn. Soc. N.S.W., 128, 2007 127
VEGETATION OF BRUNDEE AND SALTWATER SWAMPS
Table 2. Endangered Ecological Communities {ThreatenedSpecies ConservationAct 1995) found within
Brundee Swamp and Saltwater Swamp Nature Reserves and their relationship to map units defined in
this study. (The legal definitions ofEECs are provided by the Final Determinations under the TSCAct.
Diagnoses as to whether any particular area ofvegetation constitutes an EEC should be based on field
inspection and comparison with the relevant Final Determination.)
Endangered Ecological Communities listed
Corresponding Map Unit Relationship
under the TSCAct 1995
NSW
Coastal saltmarsh in the North Coast, Estuarine Saltmarsh SL p509 is included
Sydney Basin and South East Comer bioregions (SLp509) within this broader EEC
Swamp Oak Floodplain Forest ofthe NSW Floodplain Swamp Forest FOWpl05,FOWpl06
North Coast, Sydney Basin and South East (FOWpl05) and FOW pi07 are
Comerbioregions + includedwithin the
Estuarine Fringe Forest broader EEC
(FOWpl06)
+
Estuarine Creekflat Scmb
(FOWplOV)
Swamp Sclerophyll Forest on Coastal Coastal Sand Swamp Forest FOW p45 is included
Floodplains ofthe NSW North Coast, Sydney (FOW p45) within the broader EEC
Basin and South East Comerbioregions
(incorporating the formerly listed Sydney
Coastal Estuary Swamp Forest Complex in the
Sydney Basin Bioregion)
reserves is characterised by a typically dense canopy greater exposure to tidal inundation) than stands of
dominatedby Casuarinaglaucawithoccasional trees Floodplain Swamp Forest (FOW pi05), which occur
or shmbs of Melaleuca ericifolia. The understorey on slightly more elevated parts of the floodplain.
generally lacks woody plants other than sparse Elsewhere in the Sydney-South Coast region, small
juvenile individuals of the canopy species, while patches ofEstuarine Fringe Forest are scattered along
vines are generally absent. The groundcovertypically the coast to both the north and south, "fringing the
includes a prominent stratum of tussock sedges, high tide mark on the margins oftidal lakes, lagoons,
particularlyJwwcj/5 kraussi subsp. australasicus, with inlets and river estuaries" (Tindall et al. 2004). While
a groundcover of succulent forbs, Selliera radicans the mapped distribution in the Bmndee-Saltwater
and Sarcocornia quinquefaria, and other forbs, area appears atypical, it may reflect residual salinity
Commelina cyanea and Alternanthera denticulata, from formertidal flooding pattems, which have since
which are typically dispersed amongst a dense cover been modified by drainage works. It is also possible
ofleaflitterfromthecanopy. IntheBmndee-Saltwater that similar habitats to those supporting Estuarine
area, Estuarine Fringe Forest has a very similar Fringe Forest in the Bmndee-Saltwater area have
tree canopy to Floodplain Swamp Forest, although been destroyed elsewhere.
Melaleucastyphelioides does not occurinthe former. In Bmndee Swamp NR, a large area ofEstuarine
The principal differences are in the understorey, Fringe Forest (FOW pi06) is currently an open
with Estuarine Fringe Forest (FOW pi06) generally sedgeland with scattered individuals of Casuarina
having lower overall diversity, no vines and a greater glauca, which are usually immature (Fig. 6). This
abundance and diversity of succulent forbs than area is mapped as pi06a to distinguish the difference
Floodplain Swamp Forest (FOW pi05). in growth stage from the more typical form of the
Estuarine Fringe Forest has been recorded and community (mapped as pi06), which has a much
mapped primarily in low-lying areas in the northem denser and taller canopy of mature Casuarina
and central portions ofBmndee Swamp NR (Bmn08, glauca. It appears that the woody component ofthe
Bmn09) andthe westem portion ofSaltwater Swamp community is re-establishing in this area following
NR
(SaltOS), although a patch also occurs within a the exclusion of livestock after the reserve was
shallow depression in the east ofthis reserve (Salt07). declared in 2001. The difference in tree abundance is
The lower areas of the floodplain that support reflected in the Stand Basal Area at Breast Height for
Estuarine Fringe Forest are likely to experience site Bmn09 (1 m-/ha) compared to Bmn08 (33 mV
higher levels of salinity in their groundwater (due to ha). Sites within the area mapped as pi06a also have
128 Proc. Linn. Soc. N.S.W., 128, 2007
D.A. KEITH, C. SIMPSON, M.G. TOZER AND S. RODOREDA
Figure 3.Atypical stand ofFloodplain Swamp Forest showing Casuarinaglauca (background) with
Melaleuca ericifolia (foreground) and a sparse groundcover amongst a dense layer ofcompressed leaf
Utter.
a higher abundance and proportion ofexotic species portion of Brundee Swamp NR. This area has been
than sites within the area mapped as pi06, reflecting heavily affected by clearing, grazing and drainage
the association between weed invasion and livestock changes, and is currently mapped as a degraded area
grazing. of Estuarine Fringe Forest. However, the floristic
composition of BrunOS suggests that parts of this
Estuarine CreekflatScrub (FOWplO?) area could include some degraded stands ofEstuarine
Estuarine Creekflat Scrub (Fig. 7) within the Creekflat Scrub.
reserves is characterised by a typically dense canopy
dominated by Melaleuca ericifolia with occasional EstuarineSaltmarsh (SL 509)
trees ofCasuarinaglauca. The understorey generally Estuarine Saltmarsh (Fig. 8) within the reserves
lacks woody plants other than juvenile individuals isessentiallytreeless,althoughitmayhave Casuarina
ofthe canopy species. Vines ofParsonsia straminea glauca, or rarely Melaleuca ericifolia, present as
occur occasionally, either as scramblers at ground scattered shrubs. Its most prominent feature is a
level or ascending stems of canopy trees or shrubs. relativelydense,butvariablecoverofthetussockrush,
The groundcover is highly variable, with tall patches Juncus kraussi subsp. australasicus. In gaps between
ofPhragmites australis and Gahnia clarkei, patches dense patches of this rush, there is a more-or-less
of tussock sedges including Juncus spp., Carex continuouscoverofsucculentforbs,Sellieraradicans,
appressa and Cyperus lucidiis, and a scattered cover Sarcocornia quinquefaria and Lobelia anceps, and
offorbsincludingCentellaasiatica,Seneciominimus, the grass, Lachnagrostis filiformis. Patches of bare
andSelliera radicans, interspersedwith large patches ground are limited. Estuarine Saltmarsh (SL p509)
ofbare ground coveredby copious leaflitterfrom the may be difficult to distinguish from regenerating
FOW
canopy. stands of Estuarine Fringe Forest (mapped as
Estuarine Creekflat Scrub has been recorded pi06a), although saltmarsh typically occurs in local
and mapped primarily in a drainage depression at the depressions where soil conditions are more saline.
southern end ofthe Brundee Swamp floodplain (from These two communities may be in a continuous
which two ofthe three sites were recorded), although state offlux related to changes in water and salinity
smaller stands are also mapped in the south-eastern regimes.
and south-western margins ofSaltwater Swamp. The Estuarine Saltmarsh has been recorded and
third site (BrunOS) was recorded in the mid-western mapped primarily in low-lying patches in the north-
Proc. Linn. Soc. N.S.W., 128, 2007 129
VEGETATION OF BRUNDEE AND SALTWATER SWAMPS
saltmarshes encompass a diverse
group ofassemblages (Adam et al.
1988). Some ofthese assemblages
may form fine-scale mosaics
within a single stand of saltmarsh,
possibly in response to local
variations in soil salinity and tidal
inundation regimes. The Estuarine
SaltmarshintheBrundee-Saltwater
area is comparatively uniform in
composition and probably samples
the lower part of the range of
variation in soil salinity.
CoastalSandSwamp Forest
(FOWp45)
Coastal Sand Swamp Forest
(Fig. 9) within the reserves is
characterised by a relatively
dense tree canopy dominated
by Eucalyptus robusta, with
occasional trees of E. botryoides
or E. longifolia at the margins of
A
stands. diverse subcanopy is
dominatedbyMelaleucaericifolia,
with M. styphelioides, M. decora,
M. lineariifolia and Casuarina
glaucaoccurringlessfi-equentlyand
occasionally equalling the eucalypt
canopy in height. Cymbidium
suave occurs sporadically on the
tree branches. The understorey
includes varying densities of
juvenile individuals of the canopy
species, occasional clumps of the
large sedge, Gahnia clarkei, and
scattered shrubs ofvarious species.
Occasional vines of Parsonsia
straminea, Marsdenia rostrata and
Kennedia rubicunda ascend tree
trunks, festoon shrubs or scramble
along the ground. Clumps offerns,
Hypolepis muelleri and Pteridium
Figure 4.Avariant ofFloodplain Swamp Forest at Salt03 (Saltwa- esculentum, punctuateacontinuous
ter Swamp NR) showing a patch ofPhragmites australis beneath a groundcover of grasses, including
canopy ofCasuarinaglauca. Entolasia marginata, E. stricta,
Imperata cylindrica, Microlaena
stipoides, Echinopogon ovatus
western section of Saltwater Swamp NR (Salt02, and Oplismenus imbecillus, and
Salt05). In Brundee Swamp, a restricted area of forbs including Centella asiatica, Dichondra repens,
saltmarsh has been recorded and mapped along a Opercularia diphylla, Pratia purpurascens, Senecio
brackish drainage channel in the eastern part of hispidulus var. hispidulus and Veronica plebeia.
the reserve (Brun03, NOWIOA). However, the OtherfrequentgroundcoverspeciesincludeAdiantum
small occurrences of saltmarsh in Brundee Swamp aethiopicum and the twiners Cassythapubescens and
are uncertain, given the structural and floristic Glycine spp. Coastal Sand Swamp Forest is the most
resemblance to regenerating Estuarine Fringe Forest floristically rich and structurally complex vegetation
(FOW pi06a), which occurs adjacent to the putative type within the reserves, and is therefore likely to be
stands ofsaltmarsh and across large areas ofBrundee important fauna habitat.
Swamp. Coastal Sand Swamp Forest has been recorded
Elsewhere in the Sydney-South Coast region, and mapped around the southern margins of both
Estuarine Saltmarsh is scattered along the coast on Brundee (Brun06) and Saltwater (Salt09, Saltll)
mudflats associated with estuaries in locations where Swamps. Small patches have also been mapped and
thereisoccasionaltidalinundation. Collectively,these recorded to the west ofBrundee Swamp (NOW05A),
130 Proc. Linn. Soc. N.S.W., 128, 2007
D.A. KEITH, C. SIMPSON, M.G. TOZERAND S. RODOREDA
Figure 5. Estuarine Fringe Forest at SaitOS (Saltwater Swamp NR) showing a tree canopy ofCasuarina
glauca over scattered tussocks ofJuncus kraussi subsp. australasicus, and patches ofSelliera radicans
amongst copious Casuarina leaflitter.
outside the reserve. The stands in the reserves are CurrambeneLowlands Forest (DSFp85)
restricted to narrow ecotones with poorly drained, Currambene Lowlands Forest (Fig. 11) within
humic sandy soilswherethemargins ofthefloodplain the reserves is a relatively tall dry eucalypt forest
receive freshwater runoff from the toeslopes of the dominated by Corymbia maculata with Eucalyptus
surroundinghills.Thesestandsareonlypartlyincluded globoidea and E. longifolia, occasionally with
within the reserve boundaries. The stands associated E. paniculata, E. pilularis, E. punctata, Angophora
with Brundee Swamp are structurally simpler than floribunda or Syncarpia glomuUfera. Scattered trees
those associated with Saltwater Swamp, and this oiAcacia irrorata and Allocasuarina littoralis make
probably reflects the influence of past management up the subcanopy. An open shrub stratum comprises
regimes (Fig. 10). The mapped areas ofCoastal Sand Daviesia uUcifoUa, Leucopogon juniperimis,
Swamp Forest, outside the reserve, to the west of Persoonia linearis and Pittosporum undulatum, in
Brundee Swamp are associatedwith shallowdrainage addition tojuveniles ofthe canopy species. Vines and
lines in slightly more elevated terrain. twiners festoon shrubs or scramble on the ground,
Elsewhere in the Sydney-South Coast region, but rarely ascend trees. They include Billardiera
Coastal Sand Swamp Forest occurs in small stands scandens, Eustrephus latifolius, Glycine clandestina,
associated with poorly drained swales and drainage Hardenbergia violacea, Parsonsia straminea and
lines on coastal sandplains. The main areas of Hibbertiascandens.Anopengroundcoveris scattered
occurrencearearoundBotanyandJervisBays,though amongstasemi-continuouslayerofeucalyptleaflitter
littleofthe formerremains (Tindalletal. 2004). Small and occasional patches ofbare ground. It comprises
stands ofthe community are also associated with the graminoids, Entolasia stricta, Echinopogon
margins of Coomonderry Swamp. The stands in the caespitosus, E. ovata, Imperata cylindrica, Lomadra
Brundee-Saltwater area are unusual in the sense that filiformis,L. longifolia,L. multiflora,Poalabillardieri
they are associated with the margins of a floodplain and Themeda australis and a range offorbs including
ratherthan a sandplain. Brunoniellapumilio, Dianella caerulea, D. revoluta,
Dichondra repens, Lagenifera stipitata, Opercularia
Proc. Linn. Soc. N.S.W., 128, 2007 131
VEGETATION OF BRUNDEE AND SALTWATER SWAMPS
aspera, Tricoryne elatiorand Vernonia
cinerea.
Currambene Lowlands Forest
(DSF p85) occurs on hilly terrain with
well-drained yellow loams derived
from a mixture of siltstone, mudstone
and sandstone. The main occurrence is
in state forest to the south ofSaltwater
Swamp. It also occurs on a low rise
that separates Saltwater Swamp from
Brundee Swamp, where it has been
fragmented by rural development,
although a small patch occurs within
the margin of Brundee Swamp NR.
The community occurs extensively in
the Nowra - Jervis Bay area (Tindall
et al. 2004).
Illawarra Gully WetForest (WSF
p99)
A
moderate east-facing slope
on the western edge of the northern
section of Brundee Swamp NR
supports a eucalypt forest dominated
byCorymbiamaculatawithEucalyptus
paniculata and E. globoidea (Fig. 12).
The understorey includes a number of
mesophyllous shrub speciesandamore
prominent groundcover of grasses
and forbs. The most abundant shrubs
includeBursariaspinosa andNotelaea
longifolia, with Clerodendrum
tomentosum and Olearia viscidulum.
Vines of Eustrephus latifolius,
Tylophora barabata and Pandorea
pandorana are prominent amongst
the shrubs, while the groundcover is
dominated by Oplismenus imbecillus,
Microlaena stipoides, Commelina Figure 6. Regenerating stand of Estuarine Fringe Forest at
Brun09 (Brundee Swamp NR) showing young Casuarinaglauca
cyanea andDichondra repens.
(background), tussocks of Juncus kraussi subsp. australasicus,
This forest has a canopy
amidst dense growth of Aster subulatus, which overtops scat-
composition similar to stands of
tered native forbs.
Currambene Lowland Forest in the
area. However, its understorey, with an
abundanceofmesophyllous shrubs and
Other vegetation
vines,anditsprominentgroundcoverdominatedbysoft-
Some small, permanently inundated areas
leaved grasses, distinguishes it from that community, adjacent to Crookhaven River on the northern edge
which typically has a sparse sclerophyllous shrub of Saltwater Swamp NR support dense stands of
stratum and an open groundcover ofwiry graminoids
Phragmites australis that could not be sampled in
and forbs. The understorey features of the Brundee
stand more closely resemble those of two other this survey and were too small to map. These small
patches represent an example ofreedlands that may
communities described for the south coast (Tindall
previously have been more extensive on the lower
et al. 2004). The mesophyllous shrubs and vines and
Shoalhaven floodplain. Along the northern boundary
soft-leaved grasses are characteristic of Illawarra
GullyWet Forest (WSF p99), whileBursariaspinosa of Saltwater Creek NR, there are also scattered
individuals of Avicennia marina, which occurs in
and abundant grasses are characteristic of South
Coast Grassy Woodland (GW p34). Although the larger stands below the floodgates downstream on
forest onthewesternedge ofBrundee SwampNRhas Crookhaven River.
characteristics of all three of these communities, its Vegetation structure and fuel characteristics
species composition has closest overall resemblance
to Illawarra Gully Wet Forest (WSF p99), which is Coastal Sand Swamp Forest was the most
mapped on several similar sheltered slopes in the structurally complex vegetation in the study area,
vicinity by Tindall et al. (2004). with four vertical strata, each with a relatively high
cover of foliage (Table 3). Estuarine Saltmarsh had
the simplest structure, generally with only one or
132 Proc. Linn. Soc. N.S.W., 128, 2007