Ephemeral wetlands of the Pilliga Outwash, northwest NSW.

Abstract

3 Office of Environment & Heritage, Baradine, NSW 2396 AUSTRALIA Abstract: The floristic composition and vegetation partitioning of the ephemeral wetlands of the Pilliga Outwash within the Pilliga National Park and Pilliga State Conservation Area (30˚30'S, 149˚22'E) on the North Western Plains of New South Wales are described. SPOT5 imagery was used to map 340 wetlands across the Pilliga Outwash. A total of 240 plots within 31 wetlands explored composition and species richness in relation to water depth and wetland size. The predominant community described is the species-rich herbfield of shallow basin wetlands, along with the structurally distinct but the less common sedgeland/herbfield of the deeper 'tank' wetlands and a single wetland with a floristically depauperate Diplachne fusca wet grassland. A total of 131 taxa were recorded including three species listed under the NSW Threatened Species Conservation Act (1995): Eriocaulon australasicum, Lepidium monoplocoides and Myriophyllum implicatum. New records for an additional six taxa were recorded for the North Western Plains. 11% of taxa were exotic in origin.

Full text

Cunninghamia: a journal of plant ecology for eastern Australia © 2012 Royal Botanic Gardens and Domain Trust
www.rbgsyd.nsw.gov.au/science/Scientific_publications/cunninghamia
Cunninghamia
A journal of plant ecology for eastern Australia
ISSN 0727- 9620 (print) • ISSN 2200 - 405X (Online)
Date of Publication:
30/07/2012
Introduction
Wetland conservation and management requires adequate
knowledge of wetland distribution (Kingsford et al. 2004),
extent and floristic composition. In Australia impermanent
wetlands are far more common and widely distributed than
are permanent lakes and swamps (Paijmans et al. 1985)
yet in a global review of ephemeral wetlands (Deil 2005),
plot-related data were only available in the literature for
Western Australia; for the rest of the continent only general
classifications of wetland types were available at that time
(Pressey & Adam 1995). To our knowledge, since 2005,
information on temporary and ephemeral wetlands has only
been collated for some areas of New South Wales (Hunter
& Bell 2007; Bell et al. 2008; Hunter & Bell 2009). In other
areas such as western New South Wales, such information
is often only available as part of localized vegetation
description (McGann et al. 2001), regional vegetation
description (Benson et al. 2006; Benson et al. 2010), or from
descriptions of communities establishing from seed banks
(James & Capon 2007; Porter et al. 2007). Wetland covers
5.6% of New South Wales; of this portion 96% is in western
New South Wales (Kingsford et al. 2004). Kingsford et al.
(2004) list six types of spatially derived wetland groups for
New South Wales: Freshwater Lakes, Floodplain Wetland,
Estuarine Wetland, Saline Lake, Coastal Lagoons and Lakes
and Reservoirs. However in the Pilliga Scrub, south west of
Narrabri, exist a group of small ephemeral wetlands, that do
not conform to these broad wetland types, nor, unsurprisingly,
to the broad categories of wetlands described by Keith (2004).
The vegetation of these Pilliga wetlands was first described
by Benson et al. (2010), who named these wetlands Pilliga
Ephemeral wetlands of the Pilliga Outwash, northwest NSW
Dorothy M. Bell1, John T. Hunter2 & Lisa Montgomery3
1Botany, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351,
2School of Behavioural, Cognitive and Social Sciences, University of New England, Armidale, NSW 2351,
3Office of Environment & Heritage, Baradine, NSW 2396 AUSTRALIA
Abstract: The floristic composition and vegetation partitioning of the ephemeral wetlands of the Pilliga Outwash
within the Pilliga National Park and Pilliga State Conservation Area (30˚30’S, 149˚22’E) on the North Western Plains
of New South Wales are described. SPOT5 imagery was used to map 340 wetlands across the Pilliga Outwash. A total
of 240 plots within 31 wetlands explored composition and species richness in relation to water depth and wetland
size. The predominant community described is the species-rich herbfield of shallow basin wetlands, along with the
structurally distinct but the less common sedgeland/herbfield of the deeper ‘tank’ wetlands and a single wetland
with a floristically depauperate Diplachne fusca wet grassland. A total of 131 taxa were recorded including three
species listed under the NSW Threatened Species Conservation Act (1995): Eriocaulon australasicum, Lepidium
monoplocoides and Myriophyllum implicatum. New records for an additional six taxa were recorded for the North
Western Plains. 11% of taxa were exotic in origin.
Cunninghamia (2012) 12(3): 181–190
doi: 10.7751/cunninghamia.2012.12.015

182 Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga
“tank gilgai” wetland sedgeland rushland, Brigalow Belt
South Bioregion (Veg. Comm. ID 416), and considered them
to be endangered. Coincidentally this wetland community
was also described as a separate vegetation community, Tank
Herbfields, by floristic analysis within the Pilliga National
Park and Pilliga State Conservation Area (Hunter 2010).
These initial descriptions were based on a limited amount
of data and observation and a limited knowledge of wetland
distribution.
The climate of the Pilliga is dry subtropical with moderately
dry winters (Benson et al. 2010) and the majority of wetlands
are likely to fill at most once a decade. Large rainfall events
in 2010 through to early 2011 repeatedly filled the wetlands
and provided an opportunity for investigation, the intention
of which was to circumscribe the location, type and extent
of these wetlands, to describe their floristic composition and
to put them in context with other wetland types within the
region.
Methods
Study area
The area studied falls within the Brigalow Belt South
Bioregion south of the Namoi River Floodplain and forms
part of the north western portion of the 500 000 ha Pilliga
Scrub which occurs between Coonabarabran, Narrabri and
Pilliga. Most of the study area comprises outwash sands,
loams and clays resulting primarily from the erosion
of upland sandstones further to the south (Keith 2004).
Benson et al. (2010) described the wetlands as occurring on
alkaline sodic grey clay soils with sodic sandy soils in the
surrounding Buloke (Allocasuarina luehmannii) woodland.
Two ephemeral waterways, Goona Creek and Coghill Creek,
cross the study area from east to west.
We chose locations within Pilliga National Park and part of
the adjoining Pilliga State Conservation Area, in order to
investigate wetlands within an area managed for conservation
Fig. 1. Distribution of ephemeral wetlands in the Pilliga Outwash. The dotted line indicates the extent of the ephemeral wetlands area;
wetlands themselves are shown in black, borders are thickened for visibility. Wetlands occur in Pilliga National Park (Pilliga NP), in the
surrounding Pilliga State Conservation Area (Pilliga SCA) and in lands to the north and northwest of these. The area bounded by the dotted
line measures approximately 40 km by 8 km.

Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga 183
where disturbance is assumed to be more limited. Pilliga
State Conservation Area surrounds Pilliga National Park
along its eastern, southern and western boundaries (Fig. 1).
Pilliga National Park lies approximately 44 km southwest
of Narrabri (30˚ 30’ S, 149˚ 22’ E). Rainfall in 2010 was
approximately twice the yearly average with the Bureau
of Meteorology recording a total of 1119 mm in 2010 for
Baradine, southwest of Narrabri, on the western edge of the
Pilliga (30˚ 36’ S, 148˚ 58’ E, elevation 211 m, mean annual
rainfall 576 mm).
Sampling
Wetland locations were identified using SPOT5 imagery (Fig.
1). Each location was digitized and mapped with ArcGIS 9.3
and Geo-referenced SPOT5 imagery in order to measure
areas of individual wetlands using polygons. Wetland size
was verified in the field. Ground truthing of all mapped
wetlands within Pilliga National Park and Pilliga State
Conservation Area was carried out on quad bikes in the early
part of the sampling period, to distinguish depressions capable
of holding water from other bare but sloping areas such as
scalds. From the 107 depressions identified as wetlands, 31
wetlands were chosen for sampling; these covered a range of
wetland sizes and locations within the reserves.
In spring–summer 2010–2011, in each of the 31 wetlands,
up to three transects were placed in random positions across
depth gradients from the edge of the surrounding trees, to the
deepest parts of the wetland. Each transect was permanently
marked with small posts to allow sites to be revisited. The
cover abundance of all vascular species and charophytes on
a modified Braun-Blanquet (1982) scale (1–6) was assessed
in 2 m x 2 m (4 m2) plots. These plots were placed within
visually distinct vegetation bands along each transect (2 to 4
per transect; 240 plots in total). Plot water depths and distance
from the starting point were also recorded. Conductivity and
pH were measured in five wetlands in March 2011.
Appropriate plant specimens were retained for lodging in the
N. C. W. Beadle Herbarium, University of New England with
duplicates to the National Herbarium of NSW. Nomenclature
follows that of PlantNet (2011) except where recent changes
have been published elsewhere.
Analyses
Two data sets were prepared, the first of all plots separately,
the second of summed plot data for individual wetlands.
Analyses and data exploration were performed using options
available in the PATN Analysis Package (Belbin 1995a, b).
All species and their cover abundance scores were used and
the analysis performed using the Kulczynski association
recommended for ecological applications (Belbin 1995a, b)
along with flexible UPGMA fusion strategy and the default
PATN settings. Community dissimilarity was determined at
the 0.85 level.
Results
340 wetlands were mapped within the broader study area
of which 107 occurred within the Pilliga National Park and
State Conservation Area (Fig. 1). The total area covered
by these wetlands is approximately 121 ha with 92% of
wetlands being under 1 ha in size. Wetlands occurred
across a 40 km by 8 km ellipse from the Pilliga National
Park northwest to near the township of Pilliga (Fig. 1).
The wetlands occurred within a mosaic of woodlands and
shrublands largely dominated by Allocasuarina luehmanii,
Eucalyptus chloroclada, Eucalyptus pilligaensis, Eucalyptus
sideroxylon and Melaleuca densispicata (Benson et al. 2010;
Hunter 2010).
The wetlands fall into two distinct morphological types;
‘tank’, and shallow basin wetlands. ‘Tank’ wetlands are
roughly circular to irregularly oblong basins with a distinct
lip to 30 cm high, on yellowish soils with higher clay
content, often in Melaleuca densispicata tall shrubland
Fig. 2. ‘Tank’ wetland, Pilliga NP, September 2011 (Wetland 96
West, 30˚30’24”S, 149˚20’15”E).
Fig. 3. Shallow basin wetland on Old Coghill Road, Pilliga NP,
October 2010 (Wetland 37, 30˚30’26”S, 149˚22’16”E).

184 Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga
where extensive scalds are common (Fig. 2). ‘Tank”
wetlands usually contain turbid, more permanent water than
that of shallow basin wetlands, and can hold water for two
to three months. Shallow basin wetlands are on yellowish
soils of higher sand content especially at margins. There is
a sharp boundary at the woodland edge and shallow basin
wetlands are more commonly surrounded by Allocasuarina
luehmannii (Fig. 3). Water is often, but not always, clear and
the smallest wetlands dry in a matter of weeks.
A total of 131 vascular plant taxa in 49 families and 97
genera were recorded in plots and from opportunistic
sightings. Four charophyte taxa in the genera Chara and
Nitella were recorded. Families with the most taxa overall
were Asteraceae (21 species), Cyperaceae (19 species) and
Poaceae (12 species). The richest genera were Cyperus (8
species), Juncus (6 species) and Myriophyllum (4 species).
Vegetation Assemblages
Three communities were defined in the whole wetland
analysis (Figure 4):
Community 1: Cyperus gunnii subsp. gunnii – Nymphoides
crenata sedgeland/herbfield.
Wetland type: ‘Tank’ wetland. Turbid open water with a usually
continuous 1–2 m wide margin dominated by the tall sedge Cyperus
gunnii subsp. gunnii (height to 1.5 m), occasionally with floating-
leaved Nymphoides crenata populations in deepest part of basin. As
water recedes, a low (0.1–0.2 m) herbfield of ruderal species appears
on damp mud.
Terrestrial and semi terrestrial: Eragrostis elongata, Hypericum
gramineum, Commelina cyanea, Chloris truncata, Alternanthera
denticulata, Sporobolus caroli, Fimbristylis dichotoma, Eragrostis
parviflora, Cyperus gracilis, Dichelachne crinita, Dianella revoluta
subsp. revoluta.
Ruderals and mud flat colonisers: Glinus oppositifolia, Epaltes
australis, Eleocharis pusilla, Lipocarpha microcephala, Cyperus
difformis, Chenopodium pumilio, Portulaca filifolia, Fuirena incrassata.
Emergents: Cyperus gunnii subsp. gunnii, Myriophyllum simulans,
Juncus subsecundus, Eleocharis macbarroni, Juncus psammophilus,
Philydrum lanuginosum, Eleocharis plana, Mitrasacme paludosa,
Diplachne fusca, Cyperus betchei subsp betchei.
Floating-leaved: Nymphoides crenata.
Submerged: None.
Exotics: Bidens pilosa, Gomphrena celosioides, Spergularia rubra,
Xanthium occidentale.
Variability: Sometimes Cyperus gunnii subsp. gunnii margin not
intact, margins not so distinctly lipped. Generally less species-rich (9 to
20 species per wetland) than Community 2.
Community 2: Eleocharis pusilla – Myriophyllum
simulans – Nymphoides crenata – Marsilea hirsuta –
Pseudoraphis spinescens herbfield/sedgeland with an
ephemeral component dominated by Goodenia gracilis –
Centipeda minima subsp. minima – Gratiola pedunculata
– Alternanthera denticulata.
Wetland type: Shallow basin wetlands.
Terrestrial and semi terrestrial: Eragrostis elongata, Hypericum
gramineum s.lat.,Wahlenbergia tumidifructa, Wahlenbergia gracilis,
Bulbine semibarbata, Commelina cyanea, Ophioglossum lusitanicum,
Fimbristylis dichotoma, Walwhalleya subxerophylla, Chamaesyce
drummondii, Murdannia graminea, Rumex tenax, Plantago turrifera,
Lepidium monoplocoides, Portulaca oleracea, Chloris truncata.
Ruderals and mud flat colonisers: Goodenia gracilis, Centipeda
minima subsp. minima, Epaltes australis, Gratiola pedunculata,
Alternanthera denticulata, Myriophyllum implicatum, Calandrinia
pumila, Peplidium foecundum, Calandrinia eremaea, Brachyscome
goniocarpa, Crassula sieberiana, Ranunculus sessiliflorus var.
Fig. 4. Summary dendrogram of 31 ephemeral wetlands surveyed within Pilliga NP and Pilliga State Conservation Area using Kulczynski
association and flexible UPGMA fusion strategy. Communities have been defined at a dissimilarity level of c. 0.85.

Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga 185
pilulifer, Carex inversa, Cyperus flaccidus, Elatine gratioloides,
Cyperus squarrosus, Centrolepis strigosa subsp. strigosa, Centipeda
thespidioides, Eriocaulon australasicum, Lipocarpha microcephala,
Drosera indica, Isolepis hookeriana, Myriocephalus pluriflorus,
Centrolepis eremica, Helichrysum luteoalbum, Lachnagrostis filiformis,
Cyperus difformis, Callitriche sonderi, Triglochin calcitrapa, Juncus
bufonius, Portulaca filifolia, Fuirena incrassata, Calotis hispidula,
Senecio glossanthus, Plantago turrifera, Myriocephalus rhizocephalus,
Myosurus australis, Triptilodiscus pygmaeus, Polygonum plebeium,
Cyperus sanguinolentus, Lythrum hyssopifolia, Euchiton sphaericus,
Brachysome multifida var. multifida, Portulaca bicolor var. rosea,
Drosera peltata, Drosera burmanni.
Emergents: Eleocharis pusilla, Myriophyllum simulans, Cyperus
gunnii subsp. gunnii, Glossostigma diandrum, Marsilea hirsuta,
Pseudoraphis spinescens, Isoetes muelleri, Hydrocotyle tripartita,
Juncus subsecundus, Mimulus gracilis, Mitrasacme paludosa, Isotoma
fluviatilis subsp. borealis, Eleocharis plana, Marsilea costulifera,
Myriophyllum verrucosum, Diplachne fusca, Cynodon dactylon,
Eleocharis pallens, Utricularia dichotoma, Schoenus apogon,
Philydrum lanuginosum, Rorippa laciniata, Juncus psammophilus,
Juncus aridicola, Juncus flavidus, Eryngium paludosum, Eleocharis
macbarronii, Amphibromus nervosus, Cyperus rigidellus, Cyperus
gymnocaulos, Cyperus betchei subsp. betchei, Juncus ochrocoleus.
Floating-leaved: Nymphoides crenata, Nymphoides geminata,
Potamogeton sulcatus, Ottelia ovalifolia subsp. ovalifolia, Damasonium
minus, Triglochin multifructa.
Submerged: Najas tenuifolia, Vallisneria australis, Chara fibrosa,
Chara sp., Nitella sonderi, Nitella sp.
Exotics: Soliva anthemifolia, Schoenoplectus erectus, Sisyrinchium
sp. A, Sagina apetala, Conyza bonariensis, Cuscuta campestris,
Gamochaeta coarctata, Spergularia rubra, Veronica peregrina,
Anagallis arvensis, Gomphrena celosioides, Xanthium occidentale,
Vulpia bromoides, Sonchus oleraceus, Gamochaeta calviceps,
Centaurea melitensis.
Variability: This community occurred in wetlands varying greatly in
both size (<0.05 to 3.6 ha) and depth (0 to >70 cm, although the lower
limit is misleading since a few very shallow wetlands were dry when
sampled). Species richness per wetland was also highly variable (8 to
42 species) and appeared to bear no relationship to either wetland size
or wetland depth. Some quite small wetlands were species-rich, others
species-poor; the most species-rich wetland was relatively large but
other large wetlands were species-poor.
Community 3: Diplachne fusca grassland.
Wetland type: Sampled at a single site. Species-poor, very shallow
basin wetland, sandy sloping margins.
Terrestrial and semi terrestrial: Lepidium monoplocoides.
Ruderals and mud flat colonisers: Calandrinia eremaea, Epaltes
australis.
Emergents: Diplachne fusca, Cynodon dactylon.
Floating-leaved: None.
Submerged: None.
Exotics: Spergularia rubra.
Variability: Not known.
Species richness
Plot species richness across wetland depth gradients (as
distinct from richness in whole wetlands) was highly
variable. Plots in the deepest parts of the wetlands generally
had lower species richness (1–5/4m2) but variability in plots
on damp soil was very high (3–27/4m2) and did not appear
to vary with wetland size. Whole wetland richness varied
from eight in one of the smallest wetlands to 54 in one of
the largest.
The water in wetlands sampled in March 2011 was slightly
acid to slightly alkaline (pH 6.4 to 7.9). Water quality in
partially dry wetlands was good with conductivity ranging
from 181 uS/cm to 510 uS/cm.
Discussion
Two distinct communities relating to basin geomorphology
(and an additional depauperate single wetland community)
are described for the wet phase of these wetlands.
Community 2 (Eleocharis pusilla – Myriophyllum simulans
– Nymphoides crenata – Marsilea hirsuta – Pseudoraphis
spinescens herbfield/sedgeland) occurs in broad gently
sloping basins. As water recedes from the edges of this basin,
the species-rich ephemeral component (Eleocharis pusilla,
Goodenia gracilis, Centipeda minima subsp. minima,
Epaltes australis, Isoetes muelleri) is established towards
the margins and in central deeper areas, a few true aquatics
(submerged, floating-leaved and emergents e.g. Najas
tenuifolia, Potamogeton sulcatus and Triglochin procera) are
found especially in clear water (Fig. 5). In some wetlands the
deeper water has a monoculture of Myriophyllum simulans
with the edges a monoculture of Eleocharis pusilla with a
smattering of other species. Species richness per plot is much
reduced in the dry phase; in one of the largest wetlands, the
wet phase had more than twice the species richness of the
dry phase (Benson et al. 2010; Hunter 2010). There are
also some compositional differences between wet and dry
phases (see Appendix). These ephemeral wetlands are more
species rich than the semi-permanent upland wetlands of
the Northern Tablelands (Bell et al. 2008). In this sampling
season 72 species occurred in the four largest Pilliga Outwash
wetlands compared to 47 species for one sampling season in
five upland wetlands (D. Bell, unpublished data).
Morphology
The local name for these wetlands is ‘gilgai’, ‘tank gilgai’
or simply ‘tanks’. Gilgais are soil surface undulations in
desert landscapes that result from differential movements
of clay soil blocks (Hallsworth et al. 1955; Beadle 1981).
The distinctive lattice gilgai patterns on the grey cracking
clays under Brigalow to the north and northwest of Pilliga
National Park and Pilliga State Conservation Area can
clearly be distinguished on SPOT5 imagery from the
less patterned and more random ephemeral wetlands of
the Pilliga Outwash; it is unlikely that Pilliga Outwash
wetlands are formed through gilgai processes (Jim Charley
pers. comm.). The geology of Pilliga National Park is sand
plain, with sand predominant, gravel, and clay; the geology

186 Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga
northwest is channel and oodplain alluvium (Atlas of NSW
2011). Outwash wetlands are thought to be depressions
originating from former billabongs or ponds left over from
ancient drainage lines, with the ‘tank’ depressions possibly
from more recent streams and their associated wetlands (Jim
Charley pers. comm.). Similar ponds occur sporadically
today along Coghill Creek.
Variability
Multiple levels of variability in the sampling data relate to
the timing of rainfall events, sampling times, salinity and
possibly to metapopulation dynamics. There is a degree
of unpredictability in whole wetland species richness not
apparently related to wetland size. There was no obvious
explanation for some small wetlands (and some large)
having many species and others not. Some wetlands may
have more sodic soils limiting them to more salt tolerant
species or the discrepancies may be due solely to chance.
Opportunistic colonization or extinction theoretically could
result in smaller population sizes, since filling events are
highly stochastic and localized. Some wetlands were no
doubt sampled at an early establishment phase since filling;
others at a later stage when herbfields were well established.
These are common methodological issues for sampling in
aseasonal ephemeral wetlands. The isolation in space of
some of the wetland populations may also limit dispersal of
some species and result in their limitation to certain wetlands.
Further exploration of the elements of this variability could
involve further sampling in both wet and dry phases and soil
and water testing.
Wetting/drying regime
Details of the depth, frequency, duration, extent and
variability of filling of these wetlands are as yet unknown,
and likely to be unpredictably stochastic. We presume that
the wetlands only fill from overland flow after extraordinary
rainfall events or series of events, but partially fill or remain
damp for some time after any reasonably large rainfall event.
Seed banks of ruderal species are no doubt replenished as a
result of these smaller events but true aquatics (deep water
floating-leaved, submerged and emergents) rely on long-
term persistence of seeds, tubers (Triglochin multifructa) or
rhizomes (Juncus, Cyperus gunnii subsp. gunnii) in the soil.
Rainfall is not only sporadic but usually highly localized so that
some wetlands fill while others may remain dry. That fraction
that fills allow species to complete life cycles and contribute to
persistence of these wetland communities in the landscape.
Similarities to other wetlands
These small but discrete lentic wetlands are found only
within that relatively small area of the Pilliga Scrub
towards the northwestern edge of the Pilliga Outwash and
are generally associated with closely patterned ephemeral
creeks and waterways (Figure 1). In the area searched on
SPOT 5 imagery (between Pilliga township, the Namoi
River and Narrabri in the north and the Pilliga sandstone
escarpment in the south), the only other lentic wetlands
detected were occasional dams, the much larger Yarrie Lake
and the distinctly patterned lattice gilgae on heavy clays.
Shallow ephemeral wetlands with sporadic wetting and
drying cycles are however not unique to the Pilliga. Although
mostly undescribed (but see McGann et al. 2001), ephemeral
wetlands are known to occur in other semiarid to arid parts
of NSW (see Porter et al. 2007). But we are unaware of any
that are numerous enough to form aggregations in such a
relatively small area and on such distinctive geomorphology.
Growth form types
Growth form types encountered in these wetlands are similar
to those of ephemeral wetlands worldwide: dwarf annuals
or short-lived species such as Eleocharis pusilla, Crassula
sieberiana, Eriocaulon australasicum, Centrolepis eremica,
Fig. 5. Typical Community 2 changes in dominant species along a water depth gradient in two large shallow basin wetlands. The black line
indicates changes in water depth; the green line distributional changes in dominant species with depth and distance from wetland margins.

Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga 187
Callitriche sonderi, Ranunculus sessiliflorus and geophytic
perennials (species with persistent bases) such as Isoetes
muelleri and Ophioglossum lusitanicum (Deil 2005). Many
more species are ruderal or short-lived rather than perennial
and of those species establishing on damp soil few are clonal
(e.g. Eleocharis pusilla), in contrast to the strictly clonal
aquatic species of the deeper water. Not all species in the
ephemeral herbfield component are wetland specialists but
belong to those taxa encountered on damp soils in many other
situations such as in riparian areas and drainage depressions
(e.g. Epaltes australis).
Former land-use
The wetlands, especially the ‘tank’ wetlands, appear to have
been of use as a bare (i.e. tree-free) area by pastoralists. The
remains of a small stockyard was seen in one wetland; others
have remnants of fencing around them and were apparently
used with a rough one-way gate to trap and herd cattle. One
or two others provided an open area for cutting and stacking
sleepers.
Species significance
Three species currently listed on the NSW Threatened
Species Conservation Act 1995 were found within the
wetlands and six others were considered regionally
significant. The small annual herb Eriocaulon australasicum
(Family Eriocaulaceae) was occasional to common in plots
in four of the wetlands surveyed; this species is listed as
Endangered, both federally (EPBC Act) and statewide (TSC
Act), and in ROTAP (3V). There was a very early collection
along the Murray River in New South Wales (OE&H 2011a;
PlantNet 2011). Eriocaulon australasicum is known from a
few populations in Victoria and adjoining South Australia.
The annual herb Lepidium monoplocoides (Family
Brassicaceae), found scattered at wetland margins, is listed as
Endangered both federally (EPBC Act) and statewide (TSC Act)
and in ROTAP (3ECi) and is known from semi-arid regions of
New South Wales, Victoria and possibly South Australia.
Myriophyllum implicatum (Family Haloragaceae), a strictly
dioecious creeping herb (Orchard 1985) that forms discrete
mats on damp mud and can tolerate shallow water, was found
in four localized shallow basin wetlands, in one of which it
was the dominant species in an extensive band near the water’s
edge. Myriophyllum implicatum is usually confined to coastal
areas in south-eastern Queensland with an undated record
from the Hastings River in north-eastern New South Wales
(OE&H 2011b) and was considered extinct in New South
Wales until collected in 2008 by John Benson during surveys
in the Pilliga Region (Benson et al. 2010; PlantNet 2011).
Six species are considered regionally significant since they
are disjunct or thought to be at or near their geographic limits.
These taxa are: Centrolepis eremica, Drosera burmanni,
Hydrocotyle tripartita, Isoetes muelleri, Peplidium
foecundum and Philydrum lanuginosum. Of interest also
are the Nymphoides geminata populations. Nymphoides
geminata is usually homostylous but populations in the
Pilliga Outwash are consistently heterostylous.
Soil disturbance
Soil disturbance risks both disruption of the seed bank by
deeper burial of seeds and encouragement of weedy species.
Minor to extensive digging by wild pigs was seen in almost all
wetlands in 2010; pig wallows in deep holes were also seen
in September 2011. In addition, the soil surface of the more
accessible wetlands shows evidence of deep wheel tracks
of recreational vehicles (Fig. 6). Trampling and grazing by
stray cattle, feral goats and horses are also potential threats
to soil stability.
A plume of deposited soil from the erosion of a gully and
scald close to the northern boundary has the potential to
enlarge and to ultimately fill one of the ‘tank’ wetlands. Road
construction in or near wetlands is also a potential threat.
Road construction and hydrological change
A road has been constructed through the middle of one
of the mapped shallow basin wetlands with associated
roadside drains and additional drains elsewhere in the basin.
During a drought in late 2010 this drained wetland was
described as an ephemeral herbfield but with almost none
of the ephemeral wetland flora described for Community
2 (Hunter 2010). Hunter (2010) described this community
as a derived herbfield dominated by Tripogon loliiformis
and Enteropogon acicularis, floristically distinct from the
Bulbine semibarbata – Calandrinia eremaea herbfield in
an intact wetland sampled during the same survey. Some
wetlands on private property to the north and northwest
appear to have been made more permanent by impoundment.
Fig. 6. Soil disturbance by recreational vehicles in a shallow basin
wetland, Pilliga NP, September 2011 (Wetland 98, 30˚30’15”S,
149˚20’27”E).

188 Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga
Weeds
Only 11% of taxa sampled during this survey were exotic.
Of these the small sedge Schoenoplectus erectus is known
to cause problems elsewhere (Benson et al. 2010), but is not
as yet a common component of these wetland communities.
Conservation
We recommend that these ephemeral wetland communities
be considered endangered in New South Wales. Benson et
al. (2010) states that they are inadequately protected and
gives them the threat category Endangered (E/3c threat
criteria 2,4). These wetlands are relatively rare and localized
in the Pilliga Outwash landscape and are morphologically
distinct from and should not be confused with the more
common lattice gilgai depressions on grey cracking clays
under Brigalow on lands to the north and northwest. Only
one third of the mapped wetlands occur in reserves. Further
addition of lands to reserves or voluntary conservation
agreements would be beneficial to conservation, as well as
population studies of threatened species and monitoring of
weed invasion. Protection from recreational vehicles, pig
control and sedimentation is urgently required. Revisiting
and sampling the permanently marked sites in both wet
and dry phases would provide additional knowledge on the
vegetation dynamics of these communities.
Acknowledgements
The NSW Office for Environment and Heritage at Baradine
is thanked for providing vehicles and staff to assist the
survey. Sincere thanks are also due to Shane Edmonstone
who assisted the third author in quad bike ground-truthing
of wetlands, and to Kate Smiley, Daniel Bailey, and Jon
Burne for assistance with fieldwork. Ian Telford of the
N. C. W. Beadle Herbarium, University of New England
and John Hosking are thanked for assistance with species
nomenclature and identification.
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Manuscript accepted 2 April 2012

Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga 189
C1 C2 C3 Other
ALGAE
Characeae
Chara fibrosa 1
Chara sp.1
Nitella sonderi 1
Nitella sp.1
FERNS AND FERN ALLIES
Isoetaceae
Isoetes muelleri 1
Marsileaceae
Marsilea costulifera 1
Marsilea drummondii a
Marsilea hirsuta 1
Ophioglossaceae
Ophioglossum lusitanicum 1
MONOCOTYLEDONS
Asphodelaceae
Bulbine semibarbata 1
Centrolepidaceae
Centrolepis eremica 1
Centrolepis strigosa subsp. strigosa 1
Commelinaceae
Commelina cyanea 1 1
Murdannia graminea 1
Cyperaceae
Carex inversa s. lat. 1
Cyperus betchei subsp. betchei 1 1
Cyperus difformis 1 1
Cyperus flaccidus 1
Cyperus gunnii subsp. gunnii 1 1
Cyperus gymnocaulos 1
Cyperus rigidellus 1
Cyperus sanguinolentus 1
Cyperus squarrosus 1
Eleocharis macbarronii 1
Eleocharis pallens 1
Eleocharis plana 1 1
Eleocharis pusilla 1 1
Fimbristylis dichotoma 1 1
Fuirena incrassata 1 1
Isolepis hookeriana 1
Lipocarpha microcephala 1 1
*Schoenoplectus erectus 1
Schoenus apogon 1
Eriocaulaceae
Eriocaulon australasicum 1
Hydrocharitaceae
Ottelia ovalifolia subsp. ovalifolia 1
Vallisneria australis 1
Iridaceae
*Sisyrinchium sp. A 1
Juncaceae
Juncus aridicola 1
Juncus bufonius 1
Juncus continuus a
Juncus flavidus 1
Juncus ochrocoleus 1
Juncus psammophilus 1 1
Juncus subsecundus 1 1
Juncaginaceae
Triglochin calcitrapa 1
Triglochin multifructa o
Najadaceae
Najas tenuifolia 1
Philydraceae
Philydrum lanuginosum 1 1
Phormiaceae
Dianella revoluta subsp. revoluta 1
Poaceae
Amphibromus nervosus 1
Chloris truncata 1 1
Cynodon dactylon 1 1
Dichelachne micrantha 1
Diplachne fusca 1 1 1
Eragrostis elongata 1 1
Eragrostis parviflora 1
Eragrostis speciosa o
Lachnagrostis filiformis 1
Panicum decompositum a
Pseudoraphis spinescens 1
Sporobolus caroli
*Vulpia bromoides 1
Walwhalleya subxerophila 1
Potamogetonaceae
Potamogeton sulcatus 1
DICOTYLEDONS
Aizoaceae
Glinus oppositifolius 1
Alismataceae
Damasonium minus 1
Amaranthaceae
Alternanthera denticulata 1 1
*Gomphrena celosioides 1 1
Apiaceae
Eryngium paludosum 1
Hydrocotyle tripartita 1
Asteraceae
*Bidens pilosa 1
Brachyscome ciliaris var. subintegrifolia 1
Brachyscome goniocarpa 1
Brachyscome heterodonta b
Appendix 1. Vascular species and charophytes of Pilliga Outwash ephemeral wetlands. Community 1 is sedgeland/herbfield
of ‘tank’ wetlands; 2: herbfield/sedgeland with an ephemeral component in shallow basin wetlands; 3. Diplachne fusca
grassland. Exotic taxa are prefixed with an asterisk. Small letters indicate species named in other surveys or recorded
opportunistically: a: Benson (2010), b: Hunter (2010), o: opportunistic.

190 Cunninghamia 12(3): 2012 Bell, Hunter & Montgomery, Ephemeral wetlands of the Pilliga
Brachysome multifida var. multifida 1
Brachyscome nodosa a
Calotis hispidula 1
Calotis sp.1
*Centaurea melitensis 1
Centipeda cunninghamia b
Centipeda minima subsp. minima 1
Centipeda thespidioides 1
*Conyza bonariensis 1
Epaltes australis 1 1 1
Euchiton sphaericus 1
*Gamochaeta calviceps 1
*Gamochaeta coarctata 1
Helichrysum luteoalbum 1
Lemooria burkittii b
Myriocephalus pluriflorus 1
Myriocephalus rhizocephalus 1
Senecio glossanthus 1
*Soliva anthemifolia 1
*Sonchus oleraceus 1
Triptilodiscus pygmaeus 1
*Xanthium occidentale 1 1
Brassicaceae
Lepidium monoplocoides 1 1
Rorippa laciniata 1
Callitrichaceae 1
Callitriche sonderi 1
Campanulaceae
Wahlenbergia gracilenta b
Wahlenbergia gracilis 1
Wahlenbergia tumidifructa 1
Caryophyllaceae
*Sagina apetala 1
*Spergularia rubra 1 1 1
Casuarinaceae
Allocasuarina luehmannii 1
Chenopodiaceae
Chenopodium pumilio 1
Dysphania glomulifera subsp. glomulifera o
Clusiaceae
Hypericum gramineum s.lat. 1 1
Convolvulaceae
*Cuscuta campestris 1
Crassulaceae
Crassula sieberiana 1
Droseraceae
Drosera burmannii 1
Drosera indica 1
Drosera peltata 1
Elatinaceae
Elatine gratioloides 1
Euphorbiaceae
Chamaesyce drummondii 1
Gentianaceae
*Centaurium tenuiflorum 1
Goodeniaceae
Goodenia gracilis 1
Goodenia sp.
Haloragaceae
Myriophyllum implicatum 1
Myriophyllum simulans 1 1
Myriophyllum striatum a
Myriophyllum verrucosum 1
Lentibulariaceae
Utricularia dichotoma 1
Lobeliaceae
Isotoma fluviatilis subsp. borealis 1
Loganiaceae
Mitrasacme paludosa 1 1
Lythraceae
Lythrum hyssopifolia 1
Menyanthaceae
Nymphoides crenata 1 1
Nymphoides geminata 1
Myrtaceae
Eucalyptus chloroclada 1
Plantaginaceae
Plantago turrifera 1
Polygonaceae
Polygonum plebeium 1
Rumex tenax 1
Portulacaceae
Calandrinia eremaea 1 1
Calandrinia pumila 1
Portulaca bicolor var. rosea
Portulaca filifolia 1 1
Portulaca oleracea 1
Primulaceae 1
*Anagallis arvensis 1
Ranunculaceae
Myosurus minimus var. australis 1
Ranunculus sessiliflorus var. pilulifer 1
Scrophulariaceae
Glossostigma diandrum 1
Gratiola pedunculata 1
Mimulus gracilis 1
Peplidium foecundum 1
*Veronica peregrina 1