Guide to managing and restoring



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A guide to managing and restoring 

wetlands in Western Australia

Wetland vegetation and flora, part 4:

Southwest

In Chapter 2:  Understanding wetlands


ii

  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia

Contents

Part 1: Overview – separate PDF  

Includes glossary, references and appendices

Part 2: Kimberley – separate PDF

Part 3: Deserts – separate PDF

Part 4: Southwest – this PDF



Introduction  

 126

Wetland vegetation of the Southwest  

 127

Saline wetlands of the Southwest  



 128

Lagoons  



 128

Saline basin wetlands  



 132

Riverine  



 134

Springs  



 136

Freshwater wetlands of the Southwest   



 136

Groundwater fed  



 136

Perched wetlands  



 146

Wetland flora of the Southwest  

 165

Part 5: Southern Swan Coastal Plain – separate PDF



Wetland profiles

Profile of a wetland complex: Yalgorup National Park wetlands (Part 5)

Profile of a wetland complex: Brixton Street Wetlands (Part 5)


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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Introduction

Western Australia is a very large state and there is a great deal of variability in wetland 

vegetation and flora across it. The Southwest is one of three major climatic and 

biogeographical zones (Figure 86):

•  Kimberley – tropical, warm to hot all year, summer rainfall and a dry winter 

•  Deserts – hot desert, infrequent erratic rainfall 

•  Southwest – Mediterranean, warm to hot dry summer, cool wet winter.

The differing climate of these three regions drives important variations in wetland 

vegetation.

Figure 86. WA’s bioregions and the three climatic zones used in this topic. Image – C. Auricht, 

Auricht Projects.

The next major driver of the wetland vegetation and flora characteristics of the 

Southwest is whether they inhabit freshwater or saline wetlands. Wetland plant 

communities are distinctive of the zone and water chemistry, contributing both to the 

local and state identity and contributing greatly to the uniqueness of WA and Australia. 

Thirdly, in addition to zone and freshwater/saline divisions, the Southwest wetlands 

can be grouped according to the similarity of their vegetation characteristics. In the 

Southwest zone, these groups are:

•  saline lagoons

•  saline basin wetlands

•  saline riverine

•  groundwater fed

•  perched wetlands.



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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Southwest

The Southwest is world renowned for its plant diversity and large number of endemic 

plant species and communities. This diversity, combined with it being the wettest area 

of the state, has resulted in an immense variety of wetlands. Also, being in the most 

populous area of the state, these wetlands have suffered the greatest impacts from 

clearing, agriculture and urban uses, leading to loss, fragmentation and degradation.

The Southwest wetlands are the best known and most studied in WA. A substantive 

number of reports deal with a variety of plant-related wetland topics including: 

descriptions of individual wetlands, groups of wetlands and regional groups, wetland 

mapping; regional floristic data; and wetland management (related to various aspects 

such as regions, reserves, rare species and communities). However, there are no true 

regional overviews, databases or bibliographies on the Southwest’s wetland plants.

For the purposes of this topic, the Southwest incorporates nine bioregions: Yalgoo, 

Geraldton Sandplains, Avon Wheatbelt, Swan Coastal Plain, Jarrah Forest, Warren, 

Esperance Plains, Mallee and Coolgardie. The Yalgoo and Coolgardie are generally 

considered to form an inter-zone between the Desert and the Southwest but, for 

wetland vegetation and flora, are more closely related to that of the dry Southwest. 

While the nine bioregions share some wetland characteristics, the overall variety of 

wetland vegetation and flora is great.

There are fifty-eight listed nationally important wetlands in the Southwest, the most for 

any of the three wetland zones.

Wetland vegetation of the Southwest

Broadly, the vegetation of the Southwest consists of Eucalyptus-dominated tall forest and 

woodlands, Melaleuca-dominated forest and woodlands; Acacia woodlands, shrublands 

and heath, Casuarina and Banksia low woodland; mallee woodlands and shrublands, 

chenopod and samphire succulent shrublands and heath. As with the Kimberley and 

Deserts, many of these vegetation types are present in wetlands but chenopod and 

samphire succulent shrublands are confined to wetlands; further, some vegetation types 

that are common in wetlands are rare at the broader level, including sedgelands and 

herblands. There are so many wetland species in the Southwest that the most common 

taxa cannot be listed here.

From the literature reviewed during the development of this topic, in excess of several 

thousand different plant communities are potentially associated with the Southwest’s 

wetlands, depending on the scale and detail of mapping. The wetland vegetation is 

grouped below after a series of key features of the wetland habitats. 

Many wetlands combine freshwater and saline wetland features in wetland complexes. 

Two examples are provided at the end of this topic: the Yalgorup National Park wetlands 

and Brixton Street wetlands complexes. 


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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Saline wetlands of the Southwest

Saline wetlands are found in both coastal and inland locations throughout the region 

and are described below in four principal groups: lagoons, saline basin wetlands, riverine 

(including rejuvenated drainage and palaeo-drainage channels) and springs. The four 

principal groups are subdivided further.

A feature of many of these saline wetlands is freshwater areas fed by seepages/springs 

of fresh groundwater. These are described in this section on saline wetlands as they 

are a significant component of these wetlands and are becoming increasingly rare as 

groundwater levels generally decline in the Southwest. Most seepage areas associated 

with salt lakes are of freshwater, forming unique communities and providing a water 

supply for fauna. 

Lagoons


These saline wetlands are closely allied to the estuarine and marine fringing wetlands 

but have recently (in geological timeframes) been isolated from the estuary or ocean. A 

few retain seasonal linkages to the estuary or ocean and the boundaries with the saline 

estuarine areas are poorly defined. Brearley

83

 describes the estuarine systems. A number 



of wetland types are distinguished in this group and a series of examples from across the 

bioregions are used to illustrate the vegetation of each type.



Island saline wetlands

Only three of these are known and they are all included below.

•  Abrolhos Islands (Geraldton Sandplains) – These lagoons are fringed by white 

mangroves (Avicennia marina) and remain connected to the surrounding ocean. 

•  Rottnest Island* (Swan Coastal Plain) (Figure 87) – Located on Perth’s doorstep these 

are the best documented and well known of the lagoon wetlands. The island’s lakes 

are a unique wetland complex of eighteen salt lakes, sumplands and damplands, 

covering more than 180 hectares. Seven are permanently inundated (lakes). The 

three deepest lakes, Government House, Herschell and Serpentine lakes, are unique 

in Australia

9

 having cool, low-salinity water overlying warmer higher saline water 



(meromictic). In these wetlands low shrublands of Tecticornia indicaT. halocnemoides 

and Sarcocornia quinqueflora with Gahnia trifida typically fringe the water. Patches 

of Melaleuca lanceolata occur on the slight rises over the shrubs and sedges. The 

aquatic Ruppia tuberosa found in these lakes is one of only two occurrences outside 

Shark Bay. Cropped grasslands dominated by native couch (Sporobolus virginicus

grow at the freshwater seepages found dotted around some of these lakes. These 

communities are maintained by quokka grazing and are true marsupial lawns. 

Interestingly, this complex contained some freshwater wetlands, rainfall being 

perched on a marl layer. Unfortunately, these wetlands were mined for their marl, for 

use in road works. Attempts are currently being made to reform these wetlands. 

•  Recherche Archipelago Islands (Esperance Plains) – Middle Island in the Recherche 

Archipelago contains Lake Hillier, a saline lake usually coloured pink with the alga 



Duniellia salina. The vegetation of the lagoon is similar to that of the Esperance 

Coastal Lakes (see below).



Marl: fine-grained calcareous 

material (usually from dead 

charophyte algae that are able 

to biogenically precipitate 

calcium carbonate)


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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Figure 87. Rottnest Island salt lake with fringing Melaleuca lanceolata forest and samphire 

shrublands. Photo – B Keighery/OEPA.



West coast lagoonal lakes

•  Hutt Lagoon* (Geraldton Sandplains) – Hutt Lagoon (Figure 88 and Figure 89) is a 

brackish to saline wetland covering around 3,000 hectares, and fed by rain, surface 

inflows and groundwater seepage. The wetland contains a complex series of fresh 

to saline wetlands, with more than twenty distinct wetland plant communities.

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Low rises in the wetland are covered with Casuarina obesa low woodlands over 

Gahnia trifida; the flats with low succulent shrublands of Tecticornia species (T. indica

T. undulataT. syncarpa and T. halocnemoides); and the lower wetter areas with 

Sarcocornia species over Triglochin striata and Wilsonia humilis. Freshwater seepages 

occur on the eastern side of these wetlands and support sedgelands of Juncus 



kraussii subsp. australiensis and Baumea articulata

•  Leeman Lagoons (Geraldton Sandplains) – Around Leeman there are a series of 

permanently and seasonally inundated saline and gypsum wetlands with low rises 

covered by Casuarina obesa woodlands over Gahnia trifida sedgelands

85

 (Figure 



2). Freshwater seeps are located on the eastern side; one of these, Etha Springs

is dominated by Juncus kraussii subsp. australiensisCyperus laevigatus and Typha 



domingensis sedgelands. Further examples of similar types of wetland are found at 

Coolimba (Geraldton Sandplains).

•  Lake Thetis* (near Cervantes, Swan Coastal Plain) – Water in this lake is saline to 

hypersaline, with only the aquatic Ruppia tuberosa on the lake bed. Edges have 

succulent shrublands of Sarcocornia quinquefloraTecticornia halocnemoides or 

sedgelands of Gahnia trifida and Baumea juncea, all over herbs. The stromatolite 

community of Lake Thetis is a TEC.  

•  Lakes Walyungup and Cooloongup (Swan Coastal Plain) – Like most lakes in the 

Southwest, these periodically dry out and have also been called White Lakes in 

reference to the dazzling white salt beds exposed on drying (Figure 90). Low 

woodlands of Melaleuca cuticularis over sedgelands dominated by Gahnia trifida 

and/or Juncus kraussii subsp. australiensis and samphire shrublands are associated 

with these wetlands. Freshwater seepage areas on the margins of both lakes are 

associated with low or tall forests dominated by Melaleuca rhaphiophylla and/or tuart 



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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia

(Eucalyptus gomphocephala) over sedgelands dominated by Lepidosperma gladiatum

Gahnia trifida and Baumea juncea. Some of these wetland communities are the TEC 

‘Shrublands on calcareous silts of the Swan Coastal Plain’ (Figure 11).

•  Yalgorup Lakes* (Swan Coastal Plain) – The waters of these lakes are seasonally 

hyposaline (winter) or permanently hypersaline (for more information on the Yalgorup 

Lakes complex, see ‘Profile of a wetland complex: Yalgorup National Park wetlands’, 

located near the end of this topic).



Figure 88. A view of the Hutt Lagoons (Geraldton Sandplains). Photos – B Keighery/OEPA.

(a) Eastern margin dominated by Gahnia trifida sedgelands.

(b) and (c) Habit and flowers of the native Cyperus laevigatus, a cosmopolitan sedge of the 

areas with fresher water.



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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Figure 89. Another view of the Hutt Lagoons (Geraldton Sandplains). Photos – B Keighery/OEPA.

(a) Looking west towards the coastal holocene dunes across a saline flat with patches of Juncus 



kraussii subsp. australiensis sedgeland and Wilsonia humilis herbland.

(b) Flowers of Samolus repens var. paucifolius, a plant scattered through these communities. 

(c) This is a plant of the coastal saline wetlands between Shark Bay and the Yalgorup 

Wetlands. Mapping – P Gioia. Image used with the permission of the Western Australian 

Herbarium, DEC. Accessed 21/06/2011.

Figure 90. Lake Walyungup, a salt lake near Rockingham (Swan Coastal Plain).

(a) The salt encrusted dry lakebed is surrounded by bands of Juncus kraussii subsp. australiensis 

sedgelands and samphire shrublands. Wetlands with fresher water around the outside margins 

are dominated by Lepidosperma gladiatumAcacia shrublands are found on the dry rises. 

Photo – B Keighery/OEPA.

(b) Lake Walyungup lies to the west of a band of Quindalup Dunes, with Spearwood Dunes 

to the east (transect diagram reproduced and adapted from Department of Minerals and 

Energy


86

 with permission).



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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



South Coast lagoonal 

Culham Inlet Lagoons* (Esperance Sandplains) – These wetlands are estuarine areas 

where the sand bar is rarely breached; they are, therefore, no longer truly estuarine 

and are fed by naturally saline rivers. For example, Culham Inlet, fed by the Phillips and 

Steere rivers, had not breached to the sea for at least 150 years before recent clearing for 

agriculture in the catchment. Similar systems include the Fitzgerald and Dempster inlets. 

These have the same vegetation as the Esperance Coastal Lakes.

Saline basin wetlands 



Southern basin wetlands

These extend from near Frankland and Albany to east of Esperance (Figure 91). An 

example is Kwornicup Lake (Jarrah Forest), with a mosaic of vegetation units including: 

Wilsonia backhousei herbland (on the lake bed); Tecticornia syncarpa and Sarcocornia 



quinqueflora (samphires) shrubland; shrublands dominated by Melaleuca thyoidesM. 

acuminataM. viminea and M. halmaturorum; and woodlands of Casuarina obesa and/

or Eucalyptus rudis. To the east, north of the Stirling Ranges, is the Balicup System (1,400 

hectares) containing Camel, Balicup, Jebarjup and Swan lakes (Esperance Sandplains). 

The Balicup System is typical of naturally saline lakes around the range.

87

 Although the 



lake beds are largely bare, the margins are covered in zones of low samphire shrubland, 

Austrostipa juncifolia grassland and Melaleuca cuticularis woodland. Several very 

unusual species are found in the samphire shrublands, including Tecticornia uniflora

A further example of this type is the Jerdacuttup Lakes (east of Hopetoun, Esperance 

Sandplains) with Tecticornia indica samphire shrubland and a Melaleuca cuticularis forest 

to woodland.

Figure 91. Salt lake in Truslove Nature Reserve (Esperance Sandplain). Photos – B Keighery/

OEPA.


(a) Melaleuca shrubland on the low gypsum dunes and succulent shrubland adjacent to the 

bare drying lake bed.

(b) Samphire shrubs and the prostrate succulent Disphyma crassifolium subsp. clavellatum.


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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia



Esperance coastal lakes (Esperance Sandplains)

This complex includes the Lake Gore System*, Lake Warden System*, Mortijinup Lake 

System* and Pink Lake*. All are fringed by Melaleuca cuticularis woodlands often over 

a sedgeland dominated by Juncus kraussii subsp. australiensisGahnia trifidaBaumea 



juncea and/or Ficinia nodosa. Areas of samphire shrublands are also found in the system.

Swan Coastal Plain lakes/sumplands/damplands

Where groundwater is naturally saline, as in the northern Perth Basin, the lakes are 

saline. An example is Lake Eganu (north of Moora) which is bare in the middle then 

edged with zoned vegetation from Tecticornia pergranulata samphire shrubland to 



Casuarina obesa and Melaleuca cuticularis woodland. Lake Guraga (south-west of 

Cataby) has bands of vegetation relating to inundation and salinity.

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 The lake is bare 



in the centre, then fringed with a low Wilsonia backhouseiTecticornia pergranulata 

and Lawrencia glomerata shrubland, a Tecticornia indica and T. pergranulata samphire 

shrubland with herbs and grasses and finally a fringing shrubland of Melaleuca viminea

Patches of saline wetland are found within a number of predominantly freshwater 

wetlands. When these saline wetlands are on clays they support a suite of annual herbs 

and sedges (Figure 92). These same herbs and sedges are also found in some of the 

saline wetlands.

Figure 92. Some annual species renewed from seed found in the herblands of saline clayflats. 

Photos – B Keighery/OEPA.

(a) The sedge Centrolepis polygyna.

(b) Two daisies, the newly described Blennospora doliiformis (left) and Pogonolepis stricta.

(c) Angianthus drummondii, one of the wetland species recently separated from the species 

complex.


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  Wetland vegetation and flora

Chapter 2: Understanding wetlands

A guide to managing and restoring wetlands in Western Australia

Riverine

Rejuvenated drainage

Much of southern WA is composed of a low relief lateritised plateau with active 

drainage. In the higher rainfall areas (including the Jarrah Forest and Avon Wheatbelt) 

the rejuvenated drainage lines still connect to the sea and flow most years. Further 

inland, as rainfall decreases, flows decline and occur only in wet periods, forming braided 

saline drainage systems. Extensive braided drainage systems are found on all of the major 

rivers. These often have high vegetation and flora values, especially those of the Mortlock 

River and the Yenyening System on the Avon River (Avon Wheatbelt). Work on mapping 

the vegetation of the Yenyening System

36

 has distinguished twenty-two vegetation 



units, ten of these being wetland units. The saline wetland units occur in a mosaic and 

include: saline wetlands with three types of samphire shrublands, Casuarina obesa forest 

over Juncus kraussii subsp. australiensis sedgeland, Hopkinsia anaectocolea sedgeland, 

herblands, Eucalyptus sargentii woodland over chenopod shrubland, Eucalyptus 



orthostemon mallee, Melaleuca atroviridis shrubland and shrublands dominated by 

mixes of Melaleuca hamataM. brophyiM. halmaturorum and M. lateriflora. Scattered 

through the area are perched, mostly freshwater, wetlands that support Callistemon 

phoeniceus and Melaleuca thyoides shrubland and M. brevifolia shrubland over Baumea 

riparia and Juncus kraussii subsp. australiensis sedgelands. Eight species of uncommon 

flora (priority flora) are located in the wetlands, including the only known populations of 

a new Arthropodium species. All of the braided systems are threatened by hydrological 

changes.



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