Category Archives: Assisted regeneration

Re-establishing cryptogamic crust at The Waterways, Mordialloc

By Damien Cook

Photo 1.  Crytogamic crust consisting of mosses, lichens and liverworts in inter-tussock space in restored grassland at Waterways. These spaces provide recruitment opportunities for herbaceous species such as Wahlenbergia multicaulis and Brachyscome parvula

Introduction:  The Waterways is a unique urban development on the Mordialloc Creek, in Melbourne’s south eastern suburbs, which combines a housing estate with 48 hectares of restored habitat set aside for indigenous fauna and flora in open space, lakes and other wetlands. (See EMR Project summary ‘The Waterways‘.)

The revegetation of 4 hectares of native grassland and 7 hectares of swamp scrub provided the opportunity to trial the re-establishment of non-vascular plant species, as well as the higher plants which are normally the focus of restoration efforts.

Method. A diversity of cryptogams including Thuidiopsis furfurosa, Hypnum cuppressiforme, Triquetrella papillata and some Rosulabryum and lichen species were collected in the field from nearby remnants of native vegetation threatened with imminent destruction by freeway construction and new housing estates. These were placed in a blender and made into a 2 litre, thick slurry and the slurry was then diluted into a 20 litre a firefighting backpack. The diluted slurry was then applied to bare soils in the revegetated areas at the Waterways in August 2002; some areas were left untreated as a control.

Results. It was not until the wet winter of 2016 that it became apparent how successful this technique had been. There are now quite large areas with a good cover of cryptogams, particularly in the restored grassland and swamp scrub areas. There are some cryptogams in the untreated areas, but the species richness and cover are much lower. Cryptogamic crust cover appears to suppress weed germination, reducing the need for herbicide application, yet provides recruitment opportunities for native forbs (see Photos 1-3).

Acknowledgements. Thanks are due to the Haines family who were the developers of “The Waterways”, and in particular Stephen Haines, for involving us in the revegetation of the site and allowing us scope to trial different ecological restoration techniques. 

Contact: Damien Cook (rakali2@outlook.com.au)

Photo 2. Swamp Scrub at Waterways. Note the dense layer of mosses in the understory, particularly Thuidiopsis furfurosa

Photo 3. Fruiting capsules of a species of Bryum in restored native grassland at Waterways

Recovery of indigenous plants and animals in revegetated areas at ‘The Waterways’, Victoria.

Photo 1.  Aerial view of Waterways from the west

By Damien Cook

 Introduction. Waterways is a 48-hectare restoration project located on Mordialloc Creek in Melbourne’s south- eastern suburbs which combines a housing estate with large areas of restored habitat set aside for indigenous fauna and flora in open space, lakes and other wetlands (see Photo 1).

Prior to restoration the land at Waterways was a property used for grazing horses and supported pasture dominated by exotic species such as Reed Fescue (*Festuca arundinacea) and Toowoomba Canary Grass (*Phalaris aquatica). (Note that an Asterix preceding a scientific name denotes that the species is not indigenous to the local area).

The habitats which are being restored at “The Waterways” reflect those that originally occurred in the Carrum Carrum Swamp, a vast wetland complex which, prior to being extensively drained in the 1870s, stretched from Mordialloc to Kananook and as far inland as Keysborough.

Local reference ecosystems were selected to act as a benchmark for what was to be achieved in each restored habitat in terms of species diversity and cover. Habitat Hectare assessments have been used to monitor the quality of restored vegetation (see Appendix 1).

A total of nine Ecological Vegetation Classes (EVCs, the standard unit of vegetation mapping in Victoria) are being re-established across the site across the following habitats

  • Open water, Submerged Aquatic Herbfields and Exposed Mudflats
  • Densely vegetated marshes
  • Swamp Paperbark Shrubland
  • Tussock Grassland
  • Plains Grassy Woodland

Photo 2. This sequence of photographs, taken over a nine-month period at the Waterways, shows vegetation establishment in a constructed wetland from newly constructed and bare of native species on the left to well vegetated with a high cover of indigenous plants and minimal weeds on the right.

Works undertaken. Restoration of the site commenced in October 2000. Extensive weed control and earthworks were carried out prior to the commencement of revegetation works, which involved planting, by 2003, over 2 million local provenance, indigenous plants.  Grassland species were planted out of hikos at a density of 5 to 6 per square meter into areas that had been treated with both knock-down and pre-emergent herbicide. Ongoing management of the site has included ecological burning and follow up weed control. When started the Waterways was the largest and most complex ecological restoration project ever undertaken in Victoria.

Results

Plants

Open water, Submerged Aquatic Herbfields and Exposed Mudflats.  Deep, open water areas cover an area of about 30 hectares of the site. Vegetation growing in this habitat includes submerged herb-fields of Pondweeds (Potamogeton species), Eel Grass (Vallisneria australis) and Stoneworts (Chara and Nitella species), which were planted over summer 2000/01.

Densely vegetated marshes. This habitat occupies about 10 hectares of the site, occurring where water is less than 1.5 meters deep around the fringes of the lakes and as broad bands across the wetlands. Swards of large sedges including Tall Spike-rush (Eleocharis sphacelata), Jointed Twig-sedge (Baumea articulata), Leafy Twig-sedge (Cladium procerum) and River Club-rush (Schoenoplectus tabernaemontani); aquatic herb-fields of Water Ribbons (Cycnogeton procerum), Upright Water-milfoil (Myriophyllum crispatum) and Running Marsh-flower (Ornduffia reniformis); as well as meadows supporting rushes, sedges and amphibious herbs. Localized areas with high salinity (4000 to 12 000 ppm) have been planted with a halophytic (salt tolerant) community including Sea Rush (Juncus krausii), Australian Salt-grass (Distichlis distichophylla), and Shiny Swamp-mat (Selliera radicans). Planting began in the marshes at the Waterways in October 2000 and vegetation established very rapidly in most areas (see Photo 2). This vegetation type provides habitat for the locally vulnerable Woolly Water-lily (Philydrum lanuginosum).

Swamp Paperbark Shrubland covers about 8 hectares, consisting of a 1ha remnant and additional areas that were planted in spring/summer 2001. As this shrubland habitat matures it is forming a dense canopy of species including Swamp Paperbark (Melaleuca ericifolia), Prickly Moses (Acacia verticillata subsp. verticillata), Manuka (Leptospermum scoparium), Woolly Tea-tree (Leptospermum lanigerum), Tree Everlasting (Ozothamnus ferrugineus) and Golden Spray (Viminerea juncea).

Photo 3. Rare plant species that have been established in restored native grasslands at “Waterways” include Grey Billy-buttons (Craspedia canens), Matted Flax-lily (Dianella amoena) and Pale Swamp Everlasting (Coronidium gunnianum).

Tussock Grassland covers about four hectares at the Waterways between two major wetland areas. About a third of this habitat was planted in spring 2001, with the remainder in spring 2002. The dominant plants of this habitat are tussock-forming grasses including wallaby grasses (Rytidosperma species), Kangaroo Grass (Themeda triandra) and Common Tussock Grass (Poa labillardierei var. labillardierei). A diverse array of native wildflowers occurs amongst these grasses. Rare plant species that have been established in this habitat zone include Grey Billy-buttons (Craspedia canens), Matted Flax-lily (Dianella amoena) and Pale Swamp Everlasting (Coronidium gunnianum, see Photo 3).

Plains Grassy Woodland This habitat type occurs in mosaic with Tussock grassland and differs in that it supportsscattered trees and clumps of shrubs. River Red Gum (Eucalyptus camaldulensis subsp. camaldulensis) and Swamp Gum (Eucalyptus ovata var. ovata) have been planted so that they will eventually form an open woodland structure. Other tree and tall shrub species planted in this habitat include Drooping Sheoak (Allocasuarina verticillata), Blackwood (Acacia melanoxylon) and the tree form of Silver Banksia (Banksia marginata), which is now very uncommon in the local area.

Seasonal Wetlands Small seasonal wetlands occur within Tussock Grassland (see Photo 4). Rare plant species that have been established in this habitat zone include Swamp Billy-buttons (Craspedia paludicola), Woolly Water-lily (Philydrum lanuginosum), Grey Spike-rush (Eleocharis macbarronii), Giant River Buttercup (Ranunculus amplus) and the nationally endangered Swamp Everlasting (Xerochrysum palustre).


Photo 4. Seasonal rain-filled wetland at Waterways

 Animals.

The Waterways is home to 19 rare and threatened fauna species including the nationally endangered Australasian Bittern (Botaurus poiciloptilus), Glossy Grass Skink (Pseudemoia rawlinsoni) and Magpie Goose (Anseranas semipalmata). The successful establishment of diverse vegetation has so far attracted 102 species of native birds, and the wetlands on the site are home to seven species of frogs.

Open water areas support large populations of Black Swans (Cygnus atratus), Ducks (Anas species), Eurasian Coots (Fulica atra), Cormorants (Phalacrocorax and Microcarbo species), Australian Pelicans (Pelecanus conspicillatus) and Australasian Darters (Anhinga novaehollandiae) that either feed on fish and invertebrates or the foliage and fruits of water plants.  As water levels recede over summer areas of mudflat are exposed. These flats provide ideal resting areas for water birds as well as feeding habitat for migratory wading birds including the Sharp-tailed Sandpiper (Calidris acuminata), Red-necked Stint (Calidris ruficollis) and Common Greenshank (Tringa nebularia) that fly from their breeding grounds as far away as Alaska and Siberia to spend the summer in Australia and are protected under special treaties between the Governments of countries through which they travel.

Photo 5. Magpie Geese (Anseranas semipalmata) at Waterways

In 2007 a small group of Magpie Geese (Anseranas semipalmata) became regular visitors to The Waterways (see Photo 5). This species was once extremely abundant in the Carrum Carrum Swamp. However, it was driven to extinction in southern Australia in the early 1900s by hunting and habitat destruction. The Magpie Goose seems to be making a recovery in Victoria, with numbers building up from birds captured in the Northern Territory and released in South Australia that are spreading across to areas where the species formerly occurred.

Seasonal wetlands are important breeding areas for frogs including the Banjo Frog (Limnodynastes dumerilii), Striped Marsh Frog (Limnodynastes peroni) and Spotted Grass Frog (Limnodynastes tasmaniensis) and a range of invertebrates that do not occur in the larger, more permanent storm water treatment wetlands such as Shield Shrimp (Lepidurus apus viridus). Birds which utilize these wetlands for feeding include the White-faced Heron (Egretta novaehollandiae) and Latham’s Snipe (Gallinago hardwickii).

Restored grassland provides an ideal hunting ground for several birds of prey, including the Brown Falcon (Falco berigora), Black-shouldered Kite (Elanus axillaris) and Australian Kestrel (Falco cenchroides). It also provides cover and feeding habitat for insect and seed-eating birds such as the Brown Quail (Coturnix ypsilophora). A flock of about 20 Blue-winged Parrots (Neophema chrysostoma) have been regularly seen in this habitat. These parrots are usually quite uncommon in the Melbourne area. Moist grasslands beside the wetland have been colonised by the vulnerable Glossy Grass Skink (Pseudemoia rawlinsoni) (see Photo 6).

Densely vegetated marshes provide habitat for a diversity of small, secretive birds such as Ballion’s Crake (Porzana pusilla), Little Grassbird (Megalurus gramineus) and Australian Reed Warbler (Acrocephalus australis), which find suitable refuges in the cover provided by dense vegetation. Dense thickets of Swamp Paperbark shrublands provide cover and feeding habitat for Ring-tail Possums (Pseudocheris peregrinus) and bushland birds such the Eastern Yellow Robin (Eopsaltria australis), thornbills (Acanthiza species), Superb Fairy-wren (Malurus cyaneus) and Grey Fantail (Rhipidura albiscapa). As the grassy woodlands mature they are providing structural habitat diversity and accommodating woodland birds such as cuckoos (Cacomantis and Chalcites species) and pardalotes (Pardalotus species).

It will take many years for the River Red Gums to reach a majestic size and stature, and to provide tree hollows which are essential for many species of native fauna. A limited number of tree hollows are provided in the dead trees (stags) that were placed in the Waterways wetlands.

Photo 6. The vulnerable Glossy Grass Skink (Pseudemoia rawlinsoni) at Waterways

The Future. The habitats that have been created at the Waterways are about 18 years old, yet they have already attracted a vast array of native fauna. Waterways is now home to 14 rare and threatened plant species and 19 threatened animal species. There is incredible potential for the area to provide vitally important habitat for an even greater diversity of rare plants and animals as these habitats mature.

If the area is to reach its full potential careful management of weeds and pest animals is required. Ongoing monitoring of flora and fauna is also necessary. These are both areas in which the local community is becoming involved.

Acknowledgements. The high standard of restoration achieved on the Waterways project was due to the project being appropriately funded and because it was managed by ecologists experienced in planning and implementing ecological restoration.  The project was partly funded by Melbourne Water, who are now the managers of the site, and partly by a developer, the Haines Family.  This unique relationship and the generosity and willingness to try something innovative by the developer were important factors in the success of the project.

Contact: Damien Cook (rakali2@outlook.com.au)

Appendix 1. Habitat Hectare results for four quadrats at Waterways, 2006

A water point design to facilitate seed dispersal into revegetation or pasture sites

Amanda N. D. Freeman

Introduction. Although perches have been shown to enhance seed dispersal into revegetation sites, the efficacy of providing a water source to attract seed dispersers is largely untested.  In a Griffith University-led study aimed at “kick-starting” conversion of pasture to forest www.wettropics.gov.au/cfoc , bird-attracting structures that included a perch and water trough at the base were shown to enhance frugivore-assisted seed dispersal.  A complementary study in the same sites has identified the seeds of over 40 bird dispersed species deposited in the water troughs (Amanda Freeman; The School for Field Studies, Centre for Rainforest Studies (SFS-CRS) and Griffith University; 2012-2014, unpublished data).  Although the water troughs demonstrably attracted frugivorous birds, most notably Pied Currawongs (Strepera graculina ) using the water to regurgitate, any seeds regurgitated into troughs would be unavailable to germinate (Fig 1.).

Figure 1. A Pied Currawong at a water trough in a “Kickstart” pasture conversion plot. [See Elgar, A.T., Freebody, K., Pohlman, C.P., Shoo, L.P. & Catterall, C.P. (2014) Overcoming barriers to seedling regeneration during forest restoration on tropical pasture land and the potential value of woody weeds. Frontiers in Plant Science 5: 200. http://dx.doi.org/10.3389/fpls.2014.00200]

Figure 1. A Pied Currawong at a water trough in a “Kickstart” pasture conversion plot. [See Elgar, A.T., Freebody, K., Pohlman, C.P., Shoo, L.P. & Catterall, C.P. (2014) Overcoming barriers to seedling regeneration during forest restoration on tropical pasture land and the potential value of woody weeds. Frontiers in Plant Science 5: 200. http://dx.doi.org/10.3389/fpls.2014.00200%5D

Preliminary trial. Using a commercially available automatic waterer used for poultry, we designed a water point with a water dispenser that is too small for birds to regurgitate or defecate into, allowing expelled seed to fall to the ground.  The device is also simple and relatively cheap to build (<$100 Australian).  Once installed, the device requires little attention because the water remains cool and evaporation is minimal so the water may last several months without replenishing. The waterer, a plastic container which distributes water to a small dish by the action of a float, sits on a sturdy metal base 1.5m high.  The base has a perch allowing birds of different sizes to access the water from several angles and an attachment for a camera to enable bird visits to be monitored.  We envisage that the water point may facilitate seed dispersal by attracting frugivorous birds that will regurgitate and/or defecate at or near the water point.

We conducted an initial trial at a revegetation site at SFS-CRS in February 2016.  For this trial we baited the water point with Kiwi Fruit (Actinidia sp.) but this was soon consumed by insects. During the trial we recorded two species of fruit-dispersing bird, Pied Currawong and Lewin’s Honeyeater (Meliphaga lewinii) using our prototype water point within one month of its installation in (Fig 2.).

figure-2

Figure 2. A Pied Currawong drinking from a water point (kiwi fruit bait in foreground).

Design of second trial. In July 2016 we established a small trial at SFS-CRS to test the relative efficacy of perches alone versus perches coupled with our water point device in facilitating seed dispersal into cleared sites that lack remnant or planted trees.  We have nine fenced 3m2 plots in ungrazed former pasture, 15m from the edge of primary rainforest (Fig 3.).  Six plots have a perch, 3-4m high, cut to standard form from Sarsaparilla (Alphitonia petriei) trees.  Three of these plots also have a water point placed close to the base of the perch and a camera monitoring visits to the water.  Three plots have no structures.

Grass in all plots will be suppressed by herbicide spray (on an ‘as needed’ basis) and seedling recruitment in the plots will be monitored. In the first three months, no birds have been recorded using the water points in the trial plots.

Figure 3. Perch and water device trial plots, September 2016.

Figure 3. Perch and water device trial plots, September 2016.

Contact: Amanda Freeman, Centre Director, The School for Field Studies, Centre for Rainforest Studies, PO Box 141, Yungaburra, QLD 4884, Tel: +61 (7) 40953656; Email:  afreeman@fieldstudies.org

 

 

 

East Trinity remediation and rehabilitation after Acid Sulfate Soil contamination, north Queensland

Hanabeth Luke

Key words. Mangroves, estuarine habitat, migratory waders, ecological conversion

Introduction. The East Trinity case study describes the remediation of a severely degraded coastal acid sulfate soil site adjacent to the Cairns township in Queensland, Australia (Fig 1). The project involved extensive collaborative research into geochemistry, soil properties, groundwater and tidal behaviour, terrain modelling and flood modelling by a range of institutions. An innovative strategy known as lime-assisted tidal exchange (LATE) was used to reverse the acidification of the wetland, leading to improved water quality and health of coastal and estuarine ecosystems.

Acid sulfate soils are formed through a natural process that occurred when coastal lowlands were flooded in periods of high sea-level, leading to a slow build-up of metal sulfides such as pyrite. When these soils, normally protected by natural wetlands, are drained for farming or other development and exposed to oxygen, rapid oxidation of the pyrite occurred. This leads to a build-up of acidity in the soil as oxidation processes produce sulfuric acid, releasing toxic metals and noxious gases creating hostile conditions for plant growth. The acid also affects the availability of nutrients in the soil, creating another challenge for plant life. Rainfall events cause the acid, metals and nutrients to drain into waterways, impacting on aquatic ecosystems, infrastructure, fisheries and potentially, human health.

Figure 1. Aerial photo of he location of the East Trinity coastal and acid sulfate soil rehabilitation site (Source: Landsat 1999).

Figure 1. Aerial photo of he location of the East Trinity coastal and acid sulfate soil rehabilitation site (Source: Landsat 1999).

Prior condition and the degradation phase. East Trinity is a 940 ha coastal wetland situated between important estuarine habitats and a World Heritage listed wet tropical rainforest. Prior to clearing for farming, it was a mixture of paperbark woodland, tidal mangrove and salt marsh and had high ecological value for both marine and terrestrial faunal species. The area formed part of the traditional territory of the local Indigenous Mandingalbay Yidinji people.

The site was developed for sugar cane farming in the 1970s, with a bund-wall built to halt tidal inundation of the site. This drainage led to the oxidation of soil materials and a build-up of sulfuric acid in the sediments. A range of CSIRO and other reports showed that this affected 720 ha of the 940ha site. Between 1976 and 2004, it was estimated that at least 72,000 tonnes of sulfuric acid was released from the site, as well as soluble aluminium, iron, heavy metals and arsenic. Water bodies on site were routinely found to have a pH of 3.5 or lower. Aluminium levels were of particular concern, exceeding ANZECC guideline levels by as much as 6,000 times.

The discharge of acid and heavy metals led to death and dieback of vegetation (Figs 2 and 3) and had severe implications for aquatic life. These impacts were of particular concern due to the proximity of the site to the Great Barrier Reef Marine Park, with substantial evidence that acid sulfate soil runoff was discharging into reef receiving waters.

Figure 2a: Aerial view of Firewood Creek area from the 1980s showing extensive grasslands and Melaleuca leucadendra woodlands to the left of the bund wall roadway

Figure 2a: Aerial view of Firewood Creek area from the 1980s showing extensive grasslands and Melaleuca leucadendra woodlands to the left of the bund wall roadway.

Figure 2b: Aerial view of Firewood Creek area in 2013 with extensive flooded areas, Melaleuca woodland die-back and mangrove development.

Figure 2b: Aerial view of Firewood Creek area in 2013 with extensive flooded areas, Melaleuca woodland die-back and mangrove development.

Fig 3. Iron accumulation in oxidised sediments at the East Trinity site.

Fig 3. Iron accumulation in oxidised sediments at the East Trinity site.

Remediation, rehabilitation and restoration phase. The land was purchased by the QLD government in the year 2000, with the ‘Acid Sulfate Soil Remediation Action Plan’ commencing shortly thereafter. This involved a range of engineering solutions to achieved the desired hydrology and apply the lime-assisted tidal exchange remediation strategy, at first on a trial basis. Positive results during the trial period led to the long-term adoption of lime assisted tidal exchange (LATE) at East Trinity.

The LATE remediation strategy. Management strategies for acid sulfate soils are based on the principles of dilution, containment or neutralisation, with each bringing different benefits and challenges. Containment can lead to substantial acid build up and inhibit the movement of aquatic life, whilst the addition of agricultural lime can be costly. The LATE strategy (Fig. 4) was designed to support natural processes by reintroducing tidal flows, encouraging natural systems to restore the wetlands, hence greatly reducing the costs of lime and infrastructure, as well as hands-on management requirements. Flooding the soil stimulated reducing geochemical conditions whilst diluting the acidity. The bicarbonate in seawater provided a large source of alkalinity, whilst the organic matter present provided energy for microbial reactions to take place in the soil, thereby stimulating the in-situ production of alkalinity. Agricultural lime was added to the incoming tide to support the process, and also added to the out-going exit waters to prevent acid-flush into estuarine waters.

Fig 4. The image above shows some of the key parameters improved by the LATE bioremediation strategy.

Fig 4. The image above shows some of the key parameters improved by the LATE bioremediation strategy.

Results of the remediation project. The East Trinity site now has sediments at a spectrum of stages of remediation, with large areas fully remediated. Tidal inundation has ultimately led to a binding-up of heavy metals in the sediments and the neutralisation of acidity to a pH of 6.5, a typical pH for a subtropical estuarine environment. Following six years of gradually increasing tidal inundation, it was found that in-situ microbial and tidal exchange processes accounted for 99% of the change, whilst the addition of agricultural lime contributed less than 1%.

This greatly reduced the release of heavy metals to the estuarine environment and allowed for the re-establishment of mangrove and intertidal ecosystems (Fig. 2b).

Vegetation. Some ecological communities associated with the incursion of seawater and expansion of the tidal zones within the site have reduced while others have expanded. Mangrove communities have expanded and Acrostichum aureum (mangrove fern) fernlands have particularly increased, although some previous fernland transitioned to mangrove. Pasture areas have been largely replaced by Paperbark (Melaleuca leucadendra) shrublands and low woodlands and by the native grass Phragmites (Phragmites karka). The dieback of open forests of Paperbark impacted by the tidal areas continues, with some stands that were healthy in 2008 now in decline. Decline of low Clerodendrum inerme closed vinelands also continues in proximity to the tidal zone, though in other areas this community appears to be recovering.

Birds. A total of 136 species of birds have been observed at East Trinity since the rehabilitation began. Reports suggest that the expansion of mangrove and other higher elevation wetlands associated with the rehabilitation are likely to have benefited a number of bird species, including some internationally important shorebird species listed in agreements with China (CAMBA), Japan (JAMBA) and the Republic of Korea (ROKAMBA). Recently a new wader roosting site has emerged in mangroves on the northern boundary of the East Trinity area and it seems this may be significant in the regional context.

Future directions. The remediation of the East Trinity site has led to the area now having sufficiently high ecological function to be transferred back to Indigneous ownership and management.

The LATE remediation strategy’s regular tidal inundation will remain in place to ensure the acid sulfate soils remain protected from further oxidation; and monitoring and further research will continue into geochemical pathways to avoid degradation re-occurring.

Acknowledgements. The remediation of the East Trinity site and subsequent research has occurred due to the long-term efforts and collaborations between the Queensland Department of Science, Information Technology and Innovation (DSITI), CSIRO, the CRC for Contamination Assessment and Remediation of the Environment (CRC CARE) and Southern Cross University. Figures and data cited in this summary are derived from reports from these organisations available on request.

Contact. Prof Richard Bush, University of Newcastle (University Drive, Callaghan NSW 2308, Australia Tel: +61 (0)2 49215000; Email: richard.bush@newcastle.edu.au) .  Hanabeth Luke is an Associate Lecturer, Southern Cross University (Lismore, NSW 2480, Australia. Tel: +61 (0) 430092071; Email: Hanabeth.luke@scu.edu.au).

Integrating conservation management and sheep grazing at Barrabool, NSW

Martin Driver

Key words: semi-arid, grazing management, conservation management, rehabilitation, ecological restoration

Introduction. Barrabool is a 5000 ha dryland all-Merino sheep property between Conargo and Carrathool in the Western Riverina, NSW. Native pastures are the mainstay of Barrabool, as they are of other grazing properties in the arid and semi-arid rangelands of New South Wales that generally lie to the west of the 500 mm average rainfall limit.

Indigenous ecosystems at Barrabool occur as native grassland, mixed acacia and callitris woodlands and shrublands. The main grass species in the grasslands are Curly Windmill (Enteropogon sp.), White Top (Rytidosperma sp.), Box Grass (Paspalidium sp.), Speargrass (Austrostipa spp.), and Windmill Grass (Chloris sp.). Broad-leaved species include Thorny Saltbush (Rhagodia sp.), Cotton Bush (Maireana sp.) and a diverse annual forb layer in Spring..

The majority of the property has belonged to the Driver family for over 100 years. Like many of the surrounding stations a gradual but noticeable increase in exotic species occurred during the mid-to-late 20th Century, and a decline in native species. This transition has occurred because of species being transferred by livestock movements and because sheep graze not only on grass, but also saltbush shrubs and sub-shrubs as well as seedlings of native trees such as Boree (Acacia pendula) and White Cypress Pine (Callitris glaucophylla). It is well known, for example, that the preferential and continuous grazing of Boree by sheep can turn a Boree woodland into a grassland .within a manager’s lifetime unless rest and regeneration are allowed.

In recent decades – because of the Driver family’s interest in conservation and our exposure to advances in grazing management, paddock subdivision and stock water relocation – we have developed in recent decades a managed grazing system based on feed availability, regeneration capability and seasonal response to rainfall. It was our hope that this system could improve the condition of native vegetation while also improving feed availability.

Figure 1. Boree (Acacia pendula) and Thorny Saltbush (Rhagodia spinescens) in grazed paddocks at the Driver’s 5000 ha sheep property, Barabool, in the western Riverina. (Photo M. Driver).

Figure 1. Boree (Acacia pendula) and Thorny Saltbush (Rhagodia spinescens) in grazed paddocks at the Driver’s 5000 ha sheep property, Barabool, in the western Riverina. (Photo M. Driver).

Works undertaken. Over the last 35 years we have progressively fenced the property so that it is subdivided by soil type and grazing sensitivity, with watering systems reticulated through poly pipe to all those paddocks. This enables us to control grazing to take advantage of where the best feed is and move stock from areas that we are trying to regenerate at any one time; and it gives us a great deal more control than we would have had previously.

Using our grazing system, we can exclude grazing from areas that are responding with regeneration on, say Boree country, for periods of time until Boree are less susceptible to grazing; at which time we bring stock back in. We take a similar approach to the saltbush and grasses, moving sheep in when grazing is suitable and moving them off a paddock to allow the necessary rest periods for regeneration. In this way we operate a type of adaptive grazing management. We also have areas of complete domestic grazing exclusion of very diverse and sensitive vegetation which are essentially now conservation areas.

Figure 2. Mixed White Cypress Pine Woodland grazing exclosure on Barrabool with regeneration of Pine, Needlewood, Sandalwood, Rosewood, Butterbush, Native Jasmine, mixed saltbushes and shrubs. (Photo M. Driver)

Figure 2. Mixed White Cypress Pine Woodland grazing exclosure on Barrabool with regeneration of Pine, Needlewood, Sandalwood, Rosewood, Butterbush, Native Jasmine, mixed saltbushes and shrubs. (Photo M. Driver)

Results. The native vegetation at Barrabool has noticeably improved in quality terms of biodiversity conservation and production outcomes over the last 35 years, although droughts have occurred, and in fact been more frequent during this time.

In terms of conservation goals Boree regeneration and Thorny Saltbush understory restoration has been both the most extensive and effective strategy. Areas of mixed White Cypress Pine woodland have proven to be the most species diverse but also offer the greatest challenges in exotic weed invasion and management. The Pines themselves are also the most reluctant to regenerate and suffer many threats in reaching maturity while many of the secondary tree species are both more opportunistic and show greater resilience to drought and other environmental pressures. The increase in perenniality of grass and shrub components of the property have been significant, with subsequent increase in autumn feed and reduced dependence on external feed supplies.

In terms of production outcomes, after the millennium drought the property experienced three seasons in a row in which there was much less rainfall than the long term average rainfall. At the beginning of that period we had the equivalent of more than the annual rainfall in one night’s fall and then went for 12 months from shearing to shearing with no rain recorded at all. Yet the livestock and the country, however, did very well compared to other properties in the district, which we consider was due to the stronger native vegetation and its ability of the native vegetation to withstand long periods without rain.

Lessons learned and future directions. While many other sheep properties in the wider area are more intent on set stockingin their grazing practices, the results at Barrabool have demonstrated to many people who have visited the property what is possible. I am sure we are also are having some effect on the management systems of other properties in the district especially in the area of conservation areas excluded from grazing.

What we plan for the future is to explore funding options to fence out or split ephemeral creeks and wetlands and encourage Inland River Red Gum and Nitre Goosefoot regeneration.Our long term goal is to maintain the full range of management zones (including restoration zones earmarked for conservation, rehabilitation zones in which we seek to improve and maintain biodiversity values in a grazing context, and fully converted zones around infrastructure where we reduce impacts on the other zones.

Contact:   Martin Driver Barrabool, Conargo, NSW 2710 Email: barrabool@bigpond.com

Project Eden: Fauna reintroductions, Francois Peron National Park, Western Australia

Per Christensen, Colleen Sims and Bruce G. Ward

Key words. Ecological restoration, pest fauna control, captive breeding, foxes, cats.

Figure 1. The Peron Peninsula divides the two major bays of the Shark Bay World Heritage Area, Western Australia.

Figure 1. The Peron Peninsula divides the two major bays of the Shark Bay World Heritage Area, Western Australia.

Introduction. In 1801, 23 species of native mammals were present in what is now Francois Peron National Park. By 1990 fewer than half that number remained (Fig 1.). Predation by introduced foxes and cats, habitat destruction by stock and rabbits had driven many native animals to local extinction.

Project Eden was a bold conservation project launched by the WA government’s Department of Conservation and Land Management (CALM -now Dept of Parks and Wildlife) that aimed to reverse extinction and ecological destruction in the Shark Bay World Heritage Area.

The site and program. Works commenced in Peron Peninsula – an approx. 80 km long and 20 km wide peninsula on the semi-arid mid-west coast of Western Australia (25° 50′S 113°33′E) (Fig 1). In the early 1990s, removal of pest animals commenced with the removal of sheep, cattle and goats and continued with the control of feral predators. A fence was erected across the 3km ‘bottleneck’ at the bottom of the peninsula where it joins the rest of Australia (Fig 2) to create an area where pest predators were reduced to very low numbers.

Figure 2. The feral proof fence was erected at the narrow point where Peron Peninsula joins the mainland.

Figure 2. The feral proof fence was erected at the narrow point where Peron Peninsula joins the mainland.

Once European Red Fox (Vulpes vulpes) (estimated at 2500 animals) was controlled and feral Cat (Felis catus) reduced to about 1 cat per 100 km of monitored track, sequential reintroductions of five locally extinct native animals were undertaken (Figs 3 and 4).  These included: Woylie (Bettongia penicillata – first introduced in 1997), Malleefowl (Leipoa ocellata – 1997), Bilby (Macrotis lagotis – 2000), Rufous Hare-wallaby (Lagorchestes hirsutus – 2001), Banded Hare-wallaby (Lagostrophus fasciatus -2001), Southern Brown Bandicoot (Isoodon obesulus – 2006) and Chuditch (Dasyurus geoffroi geoffroi -2011?)

Methods. Cat baiting involved Eradicat® cat baits, which were applied annually during March–April at a density of 10 to 50 baits/km2. Cat baiting continued for over 10 years, supplemented with a trapping program, carried out year round over a 8 -year period. Cat trapping involved rolling 10 day sessions of leghold trapping along all track systems within the area, using Victor Softcatch No. 3 traps and a variety of lures (predominantly olfactory and auditory).Tens of thousands of trap nights resulted in the trapping of up to 3456 animals. Fox baiting involved dispersal of dried meat baits containing 1080 poison by hand or dropped from aircraft across the whole peninsula. Baiting of the peninsula continues to occur annually, and removes any new foxes that may migrate into the protected area and is likely to regularly impact young inexperienced cats in the population, with occasional significant reductions in the mature cat population when environmental conditions are favourable.

Malleefowl were raised at the Peron Captive Breeding Centre from eggs collected from active mounds in the midwest of Western Australia. Woylies were reintroduced from animals caught in the wild from sites in the southwest of Western Australia, with Bilbies sourced from the Peron Captive Breeding Centre, established by CALM in 1996 to provide sufficient animals for the reintroductions. The centre has since bred more than 300 animals from five species

Monitoring for native mammals involved radio-tracking of Bilbies, Woylies, Banded Hare Wallabies, Rufous Hare-Wallabies, Southern Brown Bandicoots, Chuditch and Malleefowl at release, cage trapping with medium Sheffield cage traps and medium Eliots, as well as pitfall trapping of small mammals. The survey method for cats utilized a passive track count survey technique along an 80 km transect through the long axis of the peninsula. The gut contents of all trapped cats were examined.

Fig. 3. Woylies were first introduced in 1997 from animals caught in the wild at sites in southwest Western Australia.

Figure 3. Once foxes were controlled and cats reduced to about 1 cat per 100 km of monitored track, sequential reintroductions of five locally extinct native animals were undertaken. Woylies were first introduced in 1997 from animals caught in the wild at sites in southwest Western Australia.

Once European Red Fox (Vulpes vulpes) (estimated at 2500 animals) was controlled and feral Cat (Felis catus) reduced to about 1 cat per 100 km of monitored track, sequential reintroductions of five locally extinct native animals were undertaken.

Figure 4. Tail tag being fitted to a Bilby. (Bilbies were re-introduced to the Peron Peninsula in 2000, from animals bred in the Peron Captive Breeding Centre.)

Results. Monitoring has shown that two of the reintroduced species – the Malleefowl and Bilby – have now been successfully established. These species are still quite rare but they have been breeding on the peninsula for several years The Woylie population may still be present in very low numbers, but despite initial success and recruitment for six or seven years, has gradually declined due to prolonged drought and low level predation on a small population. Although the released Rufous Hare-wallabies and the Banded Hare-wallabies survived for 10 months and were surviving and breeding well, they disappeared because of a high susceptibility to cat predation and other natural predators like wedge-tailed eagles. Although some predation of Southern Brown Bandicoot has occurred and the reintroduction is still in the early stages, this species has been breeding and persisting and it is hoped that they will establish themselves in the thicker scrub of the peninsula.

Lessons learned. We found that the susceptibility to predation by cats and foxes varies considerably between species. Malleefowl are very susceptible to fox predation because the foxes will find their mound nests, dig up their eggs up and eat them – consequently wiping them out over a period of time. As cats can’t dig, Malleefowl can actually exist with a fairly high level of cats. Bilbies live in their burrows and are very alert so they can persist despite a certain level of cats. But the Rufous Hare-wallaby and the Banded Hare-wallaby are very susceptible to cat predation and fox predation due to their size and habits.

Examination of the period of time when species disappeared from the Australian mainland showed that there was a sequence of extirpations, reflecting the degree to which the species were vulnerable to pest predators. The ones that survived longest are those that are less vulnerable. This suggests that if complete control of predators is not possible (considering cat control is extremely difficult), it is preferable to focus on those animals that are least vulnerable. While it could be argued that reintroductions should be delayed until such time as all the cats and foxes have been removed, such a delay (which might take us 10, 20 or even 100 years) is likely to exceed the period of time many of these species will survive without some sort of assistance. It is likely to be preferable to proceed with reintroductions although we might be losing some animals.

Future directions. As with the majority of mainland reintroduction projects, level of predator control is the key to successful establishment of reintroduced fauna. The Project is currently under a maintenance strategy and future releases, which included the Western Barred Bandicoot (Perameles bougainville), Shark Bay Mouse (Pseudomys fieldi), geoffroi), Greater Stick-nest Rat (Leporillus conditor) and Red-tailed Phascogale (Phascogale calura) are on hold until improved cat control techniques are available. Despite the uncertain future for reintroductions of these smaller species, ongoing feral animal control activities and previous reintroductions have resulted in improved conditions and recovery for remnant small native vertebrates (including thick billed grass wrens, woma pythons and native mice), and new populations of several of the area’s threatened species which are once again flourishing in their original habitats.

Acknowledgements: the program was carried out by Western Australia’s Department of Parks and Wildlife and we thank the many Departmental employees, including District and Regional officers for their assistance over the years, and the many, many other people that have volunteered their time and been a part of the Project over the years, for which we are very grateful.

Contact: Colleen Sims, Research Scientist, Department of Parks and Wildlife (Science and Conservation Division, Wildlife Research, Wildlife Place, Woodvale, WA 6026, Australia, Tel: +61 8 94055100; Email: colleen.sims@dpaw.wa.gov.au). Also visit: http://www.sharkbay.org.au/project-eden-introduction.aspx

Further detail and other work in WA:

Per E. S. Christensen, Bruce G. Ward and Colleen Sims (2013) Predicting bait uptake by feral cats, Felis catus, in semi-arid environments. Ecological Management & Restoration 14:1, 47-53.

Per Christensen and Tein McDonald (2013) Reintroductions and controlling feral predators: Interview with Per Christensen. Ecological Management & Restoration, 14:2 93–100.

 

Piccaninnie Ponds Conservation Park, South Australia

Mark Bachmann

Key words: wetland restoration, Ramsar, rising springs, drainage, hydrology

Piccaninnie Ponds Conservation Park is situated 30 km south east of Mt Gambier in South Australia. For 15-20 years after the park was proclaimed in 1969, there was considerable local interest in trying to address previous changes that had been made to the hydrology of the wetland system.

Although it was protected, reserved and supporting a diverse suite of habitats and range of resident threatened species, Piccaninnnie Ponds was far from intact from a hydrological perspective. Prior to European settlement, water that discharged from the karst, rising-spring wetlands in the system flowed eastward across the State border into the Glenelg River Estuary, in far South West Victoria.

This is how the system remained until 1906, when the first of several attempts to drain the wetlands of Piccaninnie Ponds directly to the sea occurred. What ensued was a turbulent 9 year period during which the fishermen successfully lobbied to have the creek re-directed to the Glenelg River in 1915; a step which was ultimately unpopular with affected landholders and resulted in an alternative flow path again being cut to the sea two years later in 1917. Subsequent ad hoc drainage and development of portions of the wetland system continued and by the time the Piccaninnie Ponds Conservatioon Park was proclaimed in 1969, a new main artificial outlet drained the ponds directly to the sea.

The first attempts at advocacy to restore environmental flows to the Glenelg River in the 1970s and 80s to counter this long-term drying trend in the Park were unsuccessful, until the concept was revisited and a series of steps undertaken, starting in 2001, to achieve hydrological restoration. These steps culminated in the following actions.

 Fig. 1 – Stage 1 weir and fishway under construction in 2006.

Fig. 1,  Stage 1 weir and fishway under construction in 2006.

Actions taken to correct hydrology

  1. 2006 – Stage 1 weir and fishway constructed at Piccaninnie Ponds (Figure 1) regulated outflows on the artificial outlet. This had the effect of increasing inundation in a small area immediately upstream of the structure, under the direct influence of the weir pool created by the new structure, as shown in Fig 2.
  2. 2013 – The stage 2 weir and fishway upgrade (Fig 3) resulted in the structure height being lifted to increase future management flexibility, including providing the future ability to completely block outflows, should the option of re-instating the original flow path one day become a reality.

The stage 2 upgrade was completed at the same time as providing a new flow path to physically reconnect the isolated eastern and western basins at Piccaninnie Ponds. These wetlands had been separated for several decades by a combination of lower water levels, sand drift and the impact of the Piccaninnie Ponds Road. An aerial photographic view of the new flow path is shown in Fig 4.

These works within the original Conservation Park, have occurred in in a complementary way with those that have occurred in the neighbouring, newly reserved area at Pick Swamp, each contributing to the wider vision for restoration of this wetland complex.

Fig. 2. Drained condition of habitat in 2006

Fig. 2a. Drained condition of habitat upstream of the Stage 1 weir (prior to construction  in 2006).

Fig. 3. The upstream inundation and habitat change caused by the stage 1 weir, 2012.

Fig. 2b. The upstream inundation and habitat change caused by the stage 1 weir, 2012.

Results to date.

  • Increase in quality and area of available habitat for native freshwater fish, including the nationally threatened Dwarf Galaxias (Galaxiellla pusilla)
  • Protection of hydrological processes that support a wide range of other threatened species, from a number of taxonomic groups
  • A positive trajectory of change in the distribution of wetland habitats in the vicinity of the works (increased aquatic habitat and reversal of a drying trend that was causing terrestrialisation of vegetation communities)
  • Re-establishment of connectivity between the western and eastern wetlands in the Park for the first time in several decades
Figure 4 – The lifted and redesigned stage 2 weir and fishway on the main artificial outlet at Piccaninnie Ponds – upon completion in 2013.

Fig. 3. The lifted and redesigned stage 2 weir and fishway on the main artificial outlet at Piccaninnie Ponds – upon completion in 2013.

Fig 5a. Piccaninnie

Fig. 4a. Before works – in January 2003

Figure 5 – TOP – Before works image: January 2003. BOTTOM – Post-construction/restoration image: January 2014.

Fig, 4b. After construction/restoration – in January 2014.

Future directions. The works and outcomes described here were delivered by staff working for the South Australian Department of Environment, Water and Natural Resources (DEWNR)

  • Ongoing management of the works and associated ecological monitoring in Piccaninnie Ponds Conservation Park is managed by DEWNR
  • Nature Glenelg Trust staff continue to provide specialist ecological advice and monitoring for the site when required by the site manager, DEWNR

Acknowledgements. The outcomes of the restoration project described can be attributed to a wide range of people who, in addition to the author (see current contact details below), worked at the South Australian Department of Environment, Water and Natural Resources during the period described. DEWNR project ecologists overseeing the works described here include Ben Taylor (stage 1 weir) and Steve Clarke (stage 2 weir and associated works).

The project was generously funded and supported by a range of different grants and programs administered by the South Australian Government, Australian Government and the South East Natural Resources Management Board.

Contact. Mark Bachmann. Nature Glenelg Trust, PO Box 2177, Mt Gambier, SA 5290 Australia; Tel +61 (0)8 8797 8181; Mob+61 (0) 421 97 8181; Email: mark.bachmann@natureglenelg.org.au Web| www.natureglenelg.org.au

See also:

Bradys Swamp EMR short summary

Long Swamp EMR short summary

Long Swamp, Discovery Bay Coastal Park, Victoria

Mark Bachmann

Key words: wetland restoration, Ramsar, hydrology, Glenelg River, drainage

Long Swamp is a 15 km long coastal freshwater wetland complex situated in Discovery Bay Coastal Park, approximately 50 km north-west from Portland in south-western Victoria. The wetland system supports a diverse suite of nationally threatened species and is currently undergoing a Ramsar nomination process. Despite its size, reserved status and impressive biodiversity values, including recognition on the Directory of Important Wetlands in Australia, the local community in Nelson had expressed concern for over a decade about the impact that two artificial outlets to the ocean were having on wetland condition. The outlets were cut during an era when the swamp was grazed, many decades before being dedicated as a conservation reserve in the 1970s.

The wetland originally discharged into the ocean via Oxbow Lake and the Glenelg River mouth at Nelson. These changes to hydrology caused an interruption of flows, contributing to a long-term drying trend within the wetland complex.    This was not immediately obvious to many as the gradual drying of wetlands in a natural area is often less noticeable than in a cleared agricultural area, driven by a seamless and gradual shift towards more terrestrial species within the composition of native vegetation (Fig. 1).

Figure 1. Shrub (Leptospermum lanigerum) encroachment into sedgeland underway in Long Swamp.

In 2012, Nature Glenelg Trust (NGT) became actively involved in Long Swamp, working closely with Parks Victoria, the Nelson Coast Care Group, and the Glenelg Hopkins CMA. The initial involvement was to undertake a scientific review of the aquatic ecological values that might be impacted by the ecological shifts anecdotally observed to be underway. This early work identified that the more remote artificial outlet to the sea (White Sands) had in fact naturally closed, with a dune forming in front of the former channel several years earlier during the Millennium Drought (c. 2005). This formed an area of aquatic habitat immediately upstream of the former outlet that is now home to a diverse native freshwater fish community, including two nationally threatened fish species, the Yarra Pygmy Perch (Nannoperca obscura) and Dwarf Galaxias (Galaxiella pusilla). This observation and other investigations led to the planning of a restoration trial aimed at regulating or possibly blocking the second and final artificial outlet at Nobles Rocks to increase the availability, diversity and connectivity of aquatic habitats throughout Long Swamp, in order to benefit a wide range of wetland dependant species.

As well as undertaking basic monitoring across a broad range of taxonomic groups (birds, vegetation, frogs), the project has a particular emphasis on native freshwater fish populations as a primary indicator of project success.

Figure 2 – Aerial view of Nobles Rocks artificial outlet, detailing the location of the three trial sandbag structures.

Figure 2 . Aerial view of Nobles Rocks artificial outlet, detailing the location of the three trial sandbag structures.

Figure 3 - NGT staff members celebrate the completion of the third and final sandbag structure with some of the many dedicated volunteers from the local community.

Figure 3. Nature Glenelg Trust staff members celebrate the completion of the third and final sandbag structure with some of the many dedicated volunteers from the local community.

Reversal of artificial outlet impact over three phases.

The first two stages of the restoration trial in May and July 2014 involved 56 volunteers from the community working together to construct low-level temporary sandbag structures, initially at the most accessible and technically feasible sections of drain under flowing conditions. Tackling the project in stages enabled us to learn sufficient information about the hydrological conditions at the site in 2014, before commencing the third and final stage of the trial in March 2015. On the 27th April 2015, the main structure was completed, following two days of preparation and nine days of sandbagging (using about 6,600 sandbags), which were put in place with the dedicated help of over 30 volunteers (see Figs 3 and 4). To achieve our target operating height, the structure was raised by a further 30 cm in August 2015.

A series of gauge boards with water depth data loggers were also placed at key locations in the outlet channel and upstream into Long Swamp proper, to monitor the change in water levels throughout each stage of restoration and into the future.

Fig 4a. Long swamp

Figure 4a. View of the Phase 3 Restoration Trial Structure location prior to construction in March 2015.

Fig 4b. Long swamp

Figure 4b. Same location in June 2015, after construction of the Restoration Trial Structure.

Results to date.

Water levels in the swamp immediately upstream of the final structure increased, in the deepest portion of Long Swamp, from 34 cm (in April 2015) to 116 cm (in early September 2015). Further upstream, in a shallower area more representative of the impact on Long Swamp in the adjacent wider area, levels increased from being dry in April 2015, 14 cm deep in May, through to 43 cm deep in early September 2015, as shown in Figure 5. This is a zone where the shrub invasion is typical of the drying trend being observed in Long Swamp, and hence will be an important long-term monitoring location.

To evaluate the response of habitat to short and longer-term hydrological change, we also undertook longer-term landscape change analysis through GIS-based interpretation of aerial photography. This showed that we have currently recovered approximately 60 hectares of total surface water at Nobles Rocks, not including larger gains across downstream habitats as a result of groundwater mounding, sub-surface seepage and redirected surface flows that have also been observed.  These initial results and longer-term outcomes for targets species of native plants and animals will be detailed fully in future reports.

Fig 5a. Long swamp

Figure 5a. Further inland in the swamp after the Phase 3 structure was complete, shown here in May 2015. Depth – 14 cm.

Fig 5b. Long swamp

Figure 5b. Same photopoint 4 months later in September 2015. Depth – 43 cm.

Lessons learned and future directions.Meaningful community participation has been one of the most critical ingredients in the success of this project so far, leading to a strong sense of shared achievement for all involved. Monitoring will continue to guide the next steps of the project, with the ultimate aim of informing a consensus view (among those with shared interest in the park) for eventually converting the trial structure to a permanent solution.

Acknowledgements. Project partners include Parks Victoria, Nelson Coast Care Group, the Glenelg Hopkins CMA and the Friends of the Great South West Walk. Volunteers from several other groups have also assisted with the trials. Grant funding was generously provided by the Victorian Government.

Contact. Mark Bachmann, Nature Glenelg Trust, PO Box 2177, MT GAMBIER, SA 5290 Australia, Tel +61 8 8797 8181, Mob 0421 97 8181, Email: mark.bachmann@natureglenelg.org.au  Web: www.natureglenelg.org.au

See also:

Video conference presentation

NGH newsletter – including a link to a video on the project

Bradys Swamp EMR short summary

Picanninnie Ponds EMR short summary

 

Subtropical rainforest restoration at the Rous Water Rainforest Reserve, Rocky Creek Dam, 1983 – 2016

Key words: Lowland subtropical rainforest, ecosystem reconstruction, drinking water catchment, continual improvement process.

Introduction. Rous Water is actively engaged in ecosystem reconstruction within the drinking water catchment areas it manages on behalf of the community. The aim of these activities is to improve the functioning of essential natural processes that sustain water quality. The methodology used for rainforest restoration by Rous Water has evolved over time through an ‘adaptive management’ process at Rocky Creek Dam. This adaptive management approach has demonstrated that effective large scale sub-tropical regeneration at Rocky Creek Dam is achieved through complete removal of competing plants. The technique has become known as the Woodford Method and is now being applied at other Rous Water restoration sites.

The Rous Water Rainforest Reserve at Rocky Creek Dam is set in the northern headwaters of the Richmond River catchment, on the southern rim of the Tweed shield volcano. Basalt flows from the volcano have produced nutrient rich Red Ferrosol that supported diverse sub-tropical rainforest ecosystems across the region, until the rainforest was largely cleared for agriculture in the late 19th century. The Rocky Creek Dam site is adjacent to the Big Scrub Flora Reserve, the largest remaining remnant subtropical rainforest in the region. This reserve acts as a reference site for the restoration project (Fig 1).

Figure 1. Detail of the regeneration areas at Rocky Creek Dam, showing the areas treated and the year of the initial works

Figure 1. Detail of the regeneration areas at Rocky Creek Dam, showing the areas treated and the year of the initial works

Clearing of land in the vicinity of Rocky Creek Dam by early settlers commenced in the 1890s, with the cleared lands used for the establishment of dairy farms and a sawmill. In 1949, following acquisition of the site by Rous County Council (now Rous Water) for the construction of a water supply dam, this former farmland had reverted to weedy regrowth characterised by a mosaic of native/exotic grass, Lantana (Lantana camara) and Camphor Laurel (Cinnamomum camphora) which supressed any expansion or recovery of scattered rainforest remnants. Transformation of the site commenced in 1983 when Rous Water became actively engaged in ecosystem recovery by systematically removing weeds that suppressed rainforest regeneration, a practice that continues today.

Rainforest restoration methods. The practices and management tools used in rainforest restoration at the site have been previously described by Woodford (2000) and Sanger et al. (2008). The work method typically involves the systematic poisoning and slashing of weeds to promote recruitment of rainforest plants from the soil seed bank and then to facilitate the growth of suppressed rainforest plants, providing a structural framework for further seed dispersal by wind and, particularly, flying frugivores and thus further colonisation by later phase rainforest trees.

Since 1983, an area of approximately 70 ha has been progressively treated in 1-2 ha blocks using this methodology (refer Fig 1), with progressively diminishing amounts of follow-up treatment needing to be conducted in the treated areas over subsequent years to secure successional progression of the rainforest species.

Use of this method means that, due to recruitment from the seed bank and the use of stags (from dead camphor laurel) as perches for seed dispersing birds, very limited planting has been required on the site. This has preserved the genetic integrity of the Big Scrub in this location.

Results. A total of approximately 70 hectares of weed dominated regrowth has been treated at the Rous Water Rainforest Reserve since commencement in 1983 (Figure 1). This is approximately 35 ha since the report previously published in 2000 and represents approximately 30 % of the Rous Water property at Rocky Creek Dam.

This progressive treatment of compartments of weedy regrowth at Rocky Creek Dam has continued to lead to rapid canopy closure by shorter lived pioneer and early secondary tree species, with a gradual progression to higher proportions of later secondary and primary species with increasing time since treatment. All tree species that are listed as occurring in the reference site are not only now present in the restoration area, but informal observations suggest that most, if not all, are increasing in abundance over time (Figs 2-6)

Figure 2. Treated regrowth at the Rous Water Rainforest Reserve, Rocky Creek Dam After 1 year (foreground)

Figure 2. Typical regeneration of rainforest species 1 year after Lantana removal at the Rous Water Rainforest Reserve, Rocky Creek Dam (foreground).

Figure 3. Same photopoint after 6 years

Figure 3. Typical recovery after 6 years

Figure 4. Same photopoint after 12 years

Figure 4. Typical recovery after 12 years

Figure 5. Same scenario after 20 years

Figure 5. typical recovery after 20 years

Figure 6. After 30 years

Figure 6. Typical recovery after 30 years

The structure of the older treated regrowth areas sites appears to be converging on rainforest conditions, as noted by Kanowski & Catterall (2007). Thackway & Specht (2015) depict how 25 ha of systematically treated compartments that were covered almost entirely with lantana are progressing back towards the original Lowland Subtropical Rainforest’s composition, structure and ecological function (Fig 7). Overall the vegetation status in this area was assessed at between 85% and 90% of its pre-clearing status.

This process is, at its oldest 33 years old and in some locations much younger. So it is clear that the development of the subtropical vegetation still has many decades, possibly centuries, to go, before it approaches the composition, structural and habitat characteristics of a primary forest. Notwithstanding the large areas of natural regrowth that are yet to be worked, it is evident that a large proportion of the assisted regeneration areas progressively worked by Rous over the past 33 years now requires only a low level of ongoing maintenance. This shows that these sites are maturing over time and have largely reached a self-organising state, and in the fullness of time will achieve a high degree of similarity to the reference state.  (A recovery wheel for one subsite is shown in Fig 8)

Fig 7, Thackway fig rocky creek dam1

Figure 7. Assessment of change in indicators of vegetation condition in a 25 ha area. This depicts the degree of recoveery of Lowland Subtropical Rainforest found at Rocky Creek Dam, Big Scrub, NSW against a pre-clearing reference. (Graph reproduced with permission. The method used to generate the graph is described in Thackway, R. and Specht, A., (2015). Synthesising the effects of land use on natural and managed landscapes. Science of the Total Environment. 526:136–152 doi:10.1016/j.scitotenv.2015.04.070. ) Condition indices for transition Phase 4 were derived from prior reports including Sanger et al. 2008 and Woodford 2000. Metadata can be viewed at http://portal.tern.org.au/big-scrub-rocky-queensland-brisbane/16908 .

Lessons learned. Using this method of harnessing the natural resilience processes of the rainforest, we have been able to progress the recovery of an important water catchment area, restoring very high biodiversity conservation values in a landscape where rainforest was, and remains, in serious decline., The ability of the high resilience sites at Rocky Creek Dam to respond to the Woodford Method is clearly demonstrated, but there is ample evidence that application of this and similar resilience-based rainforest restoration methods can harnessed resilience at other sites in the Big Scrub that are at greater distances from remnants.

Figure 8. Distribution of management intensity classes across the Rous Water Rainforest Reserve at Rocky Creek Dam.

Figure 8. Distribution of management intensity classes across the Rous Water Rainforest Reserve at Rocky Creek Dam. (Legend for this map is in Appendix 1)

Current work and future directions. Work continues at the site and management is supportive of-site evaluation to assess the extent to which the treated areas are undergoing successional development using a range of available assessment tools.

To assist future planning, and in order to address the issue of how to best estimate and plan for restoration works and associated costs, Rous Water has adapted the methodology developed on the Tweed-Byron Bush Futures Project, where each restoration site/area was assigned a Management Intensity Class (MIC) based on a generalised assessment of site condition, weed composition and cover and other management requirements. (Fig 8) The MIC describes the frequency of restoration work required to restore the site to a minimal maintenance level and how many years this would take to achieve. The MIC aims to describe the extent of management intervention necessary to restore the site to a minimal maintenance level. For this analysis this equates to the establishment of a self sustaining sub-tropical rainforest buffer zone. Each management intensity class is associated with a particular restoration trajectory/cost per hectare, based on visitation frequency by a standard 3 person team and expressed in terms of number of visits required to control / manage weeds. Appendix 1 below shows details of the MIC classification, showing for each class, relevant site criteria, and the estimated level of bush regeneration resources required to bring each class to a low maintenance level.

Contact: Anthony Acret, Catchment Assets Manager,  Rous Water. Tel: +61 (0) 2 6623 3800, Email: anthony.acret@rouswater.nsw.gov.au

Rocky Creek Dam recovery wheel adjacent to Forest Edge

Appendix 1. Legend for Management intensity classes used in Fig 8. (From Tweed-Byron Bush Futures)

Appendix 1. Legend for Management intensity classes used in Fig 8.

Establishment of an assisted natural regeneration model for Big Scrub sub-tropical rainforest: The Woodford Method

The results of long-term restoration at Rocky Creek Dam, have informed the development of an assisted natural regeneration model for sub-tropical rainforest known as The Woodford Method (named after the pioneering restoration work of Ralph Woodford). This method is now commonly applied across the Big Scrub region, particularly on high resilience sites and is more fully explained in Woodford (2000).

Figure 1. Remove Lantana thickets.

Figure 1. Remove Lantana thickets.

1. Winter (July-August) – refer Figure 1. In a typical area of secondary regrowth dominated by weeds such as Camphor Laurel (Cinnamomum camphora), Privet (Ligustrum sinense) and Lantana (Lantana camara), Lantana is the weed that should be killed first. Winter is the best time to do this as it is dry and it won’t reshoot when on the ground. In extensive areas, this can be done effectively by flattening thickets of Lantana with a tractor, then slashing it repeatedly to create a deep mulch, and pulling the Lantana stumps out to disturb the soil. Removing the Lantana thickets also allows access to tree weeds.

Figure 2. Kill Privet and Camphor Laurel.

Figure 2. Kill Privet and Camphor Laurel.

2. Spring (September-October) – refer Figure 2. Tree weeds such as Camphor and Privet have their biggest growth spurt, so this is a good time to give them a shot of herbicide to kill them. (Leaving the Camphor in place rather than cutting them down means that they act as ‘perch trees’ for birds and bats to land on and spread seeds through their droppings). As the Lantana, Camphor and Privet die, their leaves and branches fall to the ground and form a rich mulch on the forest floor. Light is also able to reach the forest floor, where previously it had only reached the canopy.

Spring storms come and wet the mulch, and fungal mycelium (the feeding filaments of fungi) move through the mulch and break it down, fertilising and leaving bare patches of soil where the mulch layer has totally receded.

Figure 3. Remove annual weeds.

Figure 3. Remove annual weeds.

3. Late spring / early summer (November-January) – refer Figure 3. Where you have bare soil, and there is moisture, light and an appropriate temperature, you will get seed germination. The first things to come up are annual weeds such as ‘Farmers Friends’ or ‘Cobblers Pegs’ (Bidens pilosa); ‘Blue Billy Goat Weed’ (Ageratum houstonianum); and ‘Crofton’ or ‘Mistweed’ (Ageratina spp). Annual weeds are always first to appear. They will germinate on the smell of a storm and a slight increase in temperature. Camphor and privet seedlings often come up at the same time.

When the weeds grow, they form a canopy just like the forest but at a height of one metre. In this way, weeds stop light from reaching the forest floor, inhibiting the growth of rainforest seedlings.

Therefore, it is important to remove these annual weeds and not let them go to seed. Depending on time available they are either pulled or sprayed. The experience at this site has been that the seedbank is strong enough to lose some rainforest seedlings in this initial spraying. If using herbicide, two sprays during this season generally removes all the weeds and their seeds.

Figure 4. Weed around rainforest seedlings.

Figure 4. Weed around rainforest seedlings.

4. Late summer / early autumn (February-March) – refer Figure 4.The seeds of rainforest species tend to germinate after the highest summer temperatures (sometimes up to 38 and 40 degrees) have passed. By late February and early March, daytime temperatures don’t generally go over 30 degrees, but the soil temperature and moisture is at its maximum. These conditions can produce a massive germination of rainforest seeds and those seedlings grow up very rapidly. Hand weeding is usually needed around these rainforest ‘pioneers’.

Figure 5. Enjoy the growing rainforest.

Figure 5. Enjoy the growing rainforest.

5. Early winter (May-June) – refer Figure 5. On a good site, with the best seasonal conditions, many of these rainforest seedlings will have grown to saplings above head height and can create a closed canopy within the same year. This means that less light reaches the forest floor, which reduces the amount of weed regrowth in this area – but there is still enough light for later successional rainforest seedlings to germinate, building the rainforest diversity over time.

Note: The process may be slightly different depending on the type of ‘before restoration’ landscape. Refer to Woodford (2000) for more information.

Contact: Anthony Acret,  Catchment Assets Manager, Rous Water, NSW Australia. Tel+62 2 6623 3800; Email: anthony.acret@rouswater.nsw.gov.au