Category Archives: New South Wales

A novel multispecies approach for assessing threatened swamp communities

Hannah McPherson and Maurizio Rossetto,

Key words:   Swamp conservation, chloroplast DNA, genetic diversity, landscape connectivity

Introduction. Little is known about the historical or present-day connectivity of Temperate Highland Peat Swamps on Sandstone (THPSS) in the Sydney Basin (NSW). Recent technological advances have enabled exploration of genetic complexity at both species and community levels.  By focusing on multiple plant species and populations, and investigating intraspecific gene-flow across multiple swamps, we can begin to make generalisations about how species and communities respond to change, thereby providing a solid scientific basis from which appropriate conservation and restoration strategies can be developed.

The study area comprised eight swamps distributed across four sites along an altitudinal gradient: Newnes (1200m); Leura (900m); Budderoo (600m); and Woronora (400m), see figure 1.

Map of the Sydney Basin region showing four study sites and eight swamps. Greyscale shows altitude gradient.

Map of the Sydney Basin region showing four study sites and eight swamps. Greyscale shows altitude gradient.

The aims were:

  • To assess the relative genomic diversity among target species representing a range of life-history traits. This was achieved by sequencing chloroplast DNA and detecting variants in pooled samples from 25 species commonly occurring in swamps.
  • To explore geographic patterns of diversity among swamps and across multiple species by designing targeted genomic markers and screening variants among populations within and between sites (for ten species occurring in up to 8 swamps).
  • To develop a set of simple, effective and standardised tools for assessing diversity, connectivity and resilience of swamps to threats (from mining to climate change).
Fig 2. Broad Swamp, Newnes Plateau (Maurizio Rossetto)

Fig 2. Broad Swamp, Newnes Plateau (Maurizio Rossetto)

Our study comprises three main components:

1. Species-level assessment of genetic variation of swamp species

We have taken advantage of new available methods and technologies (McPherson et al. 2013 and The Organelle Assembler at http://pythonhosted.org/ORG.asm/) to sequence and assemble full chloroplast genomes of 20 plant species from swamps in the Sydney Basin and detect within and between-population variation. This enabled a rapid assessment of diversity among representatives of 12 families and a broad range of life-history traits – e.g. table 1. We are currently finalising our bioinformatic sampling of the data to ensure even coverage of chloroplast data across the species, however these preliminary data show that relative estimates are not a product of different amounts of chloroplast data retrieved (e.g. for the seven species with sequence length greater than 100,000 base pairs variation ranges from absent to high).

2. Swamp-level assessment of variation and connectivity using three target species – Baeckea linifolia (high diversity), Lepidosperma limicola (low diversity) and Boronia deanei subsp. deanei (restricted and threatened species).

From the initial species-level study we selected three very different species for detailed population-level studies. We designed markers to screen for variation within and among sites and explore landscape-level connectivity. We identified the Woronora Plateau as a possible refugium and we have uncovered interesting patterns of gene-flow on the Newnes Plateau. Two species, Lepidosperma limicola and Baeckea linifolia seem able to disperse over long distances while Boronia deanei subsp. deanei showed unexpected high levels of diversity despite very limited seed-mediated gene-flow between populations. Its current conservation status was supported by our findings. A unique pattern was found for each species, highlighting the need for a multispecies approach for understanding dynamics of this system in order to make informed decisions about, and plans for, conservation management.

3. Multi-species approach to assessing swamp community population dynamics

Since the population study approach proved successful we expanded our study to include population studies for a further ten species. This required development of new Next Generation Sequencing (NGS) approaches applicable to a wide range of study systems. This kind of approach will allow us to make informed generalisations about swamp communities for conservation management planning.

Fig 3. Paddy’s Swamp, Newnes Plateau (Anthea Brescianini)

Fig 3. Paddy’s Swamp, Newnes Plateau (Anthea Brescianini)

Table 1. Preliminary results showing relative chloroplast variation among 25 swamp species. Sequence length is in base pairs (bp) and relative level of variation was calculated as sequence length divided by number of variants to obtain an estimate of number of SNPs per base pair.  Relative variation was then categorised as: High (one SNP every <1,000 bp); Moderate (one SNP every 1,000 – <5,000 bp); Low (one SNP every 5,000 – <10,000 bp); Very low (one SNP every >10,000 bp); or absent (no SNPs).

table

Fig 4. Banksia ericifolia (Maurizio Rossetto)

Fig 4. Banksia ericifolia (Maurizio Rossetto)

Results to date. We have assembled partial chloroplast genomes of 20 plant species from THPSS in the Sydney Basin and categorised relative measurements of diversity. Preliminary data from the three target species highlighted the need for multispecies studies and we are now finalizing our results from an expanded study (including 13 species) in order to better understand connectivity and resilience of THPSS and provide data critical for more informed conservation planning. We have produced unique, simple methods for assessing genetic diversity and understanding dynamics at both the species and site levels.

Lessons learned and future directions. We found that individual species have unique patterns of genetic variation that do not necessarily correspond with phylogeny or functional traits and thereby highlight the benefit of multispecies studies. We have developed a unique, simple method for screening for genetic variation across whole assemblages which can be applied to many study systems. Since our data capture and analysis methods are standardised it will be possible in the future to scale this work up to include more species and/or more geographic areas and analyse the datasets together to address increasingly complex research questions about the resilience of swamps in a changing landscape.

Stakeholders and Funding bodies. The following people have contributed to many aspects of this research, including design, fieldwork and data generation and analysis: Doug Benson and Joel Cohen (Royal Botanic Gardens and Domain Trust), Anthea Brescianini and Glenda Wardle (University of Sydney), David Keith (Office of Environment and Heritage).

This research was funded through the Temperate Highland Peat Swamps on Sandstone Research Program (THPSS Research Program). This Program was funded through an enforceable undertaking as per section 486A of the Environment Protection and Biodiversity Conservation Act 1999 between the Minister for the Environment, Springvale Coal Pty Ltd and Centennial Angus Place Pty Ltd. Further information on the enforceable undertaking and the terms of the THPSS Research Program can be found at www.environment.gov.au/news/2011/10/21/centennial-coal-fund-145-million-research-program.

Contact. Hannah McPherson, Biodiversity Research Officer, Royal Botanic Gardens and Domain Trust, Mrs Macquaries Road, Sydney 2000; Tel: +61292318181 Email: hannah.mcpherson@rbgsyd.nsw.gov.au

Hydrology of Woronora Plateau Temperate Highland Peat Swamps on Sandstone

William C Glamore and Duncan S Rayner

Key words: water balance, groundwater, soil, subsidence, under mining

Introduction. The Temperate Highland Peat Swamps on Sandstone (THPSS) ecological community consists of both temporary and permanent swamps developed in peat overlying Triassic Sandstone formations at high elevations, generally between 400 and 1200 m above sea level on the south-east coast of Australia. THPSS are listed as an endangered ecological community (EEC), threatened by habitat destruction and modification of groundwater and hydrology. The primary impact of longwall mining is to swamp hydrology, influencing long-term surface and groundwater regimes. This, in turn, can have a devastating impact on swamp ecology including many important habitats for protected flora and fauna. While the ecological value of THPSS is well understood, our current understanding of the hydrology of THPSS is limited. THPSS have been found to be dependent on groundwater, and subsequently the impact of modifying groundwater interactions can be significant. Recent research has concluded that a thorough understanding of the impact of longwall mining on the surface waterways and groundwater system is necessary before any remediation options to reduce loss of water into subsurface routes and minimise impact on water quality are considered.

Aims. To address this major knowledge gap, research into the fundamental hydrology of THPSS was undertaken. The purpose of this investigation was to understand the role of surface water and groundwater inputs and losses in maintaining swamp hydrology, providing a base level foundation from which the impacts of long-wall mining on ecology can be determined and guide future remediation efforts. To undertake on-ground research, multiple locations where data collection in peat swamps was being undertaken were utilised to form a foundation from which to expand swamp investigations and target site data gaps. Two swamps were selected for further detailed investigations, both located on the Woronora Plateau, approximately 80km south of Sydney, Australia. One site was within the Woronora Nature Reserve, where vegetation has been monitored regularly for 30+ years and basic climate monitoring for the past 5 years, and another swamp within the Sydney Metropolitan Catchment Management Area where climate monitoring, groundwater levels and swamp discharge has been monitored for the previous 5 years.  Extensive on-ground investigations were undertaken (and continue to be monitored) at these sites, providing fundamental scientific information for further assessment.

Methods. A series of groundbreaking on-ground investigations were undertaken to characterize the swamp hydrogeology and surface hydrology.  Detailed surveys of peat depth were initially undertaken using a push rod and RTK-GPS to determine digital elevation models (DEM) of surface topography and subsurface sandstone. Depth to underlying sandstone was found to be variable throughout the swamps (Figure 1). This survey guided the location and density of soil profiles and piezometer installations to characterize sediment characteristics, monitor water level fluctuations and assess water and soil chemistry.  A total of 17 piezometers were installed to bed rock, including logging soil stratigraphy and soil grab samples. Slotted 50mm diameter PVC was installed with a water level logger deployed near the bedrock. Soil samples were analysed for pH, EC, moisture, organic matter and a suite of analytes via ion chromatography. Hydraulic conductivity of the upper peat layer was also tested in-situ. Collected field data and site characterization surveys were combined to construct a three-dimensional numerical hydrological groundwater model to assist in determining the swamp water balance, hydrodynamics and to refine future sampling/analysis.

Figure 1: Example swamp depth survey and piezometer locations with conceptual groundwater flow paths

Figure 1: Example swamp depth survey and piezometer locations with conceptual groundwater flow paths

Findings. Findings include fundamental swamp hydrogeolgical characteristics, water balance summaries and analysis of degrees of freedom.  Swamp sediments were observed to vary both within swamps and between swamps. Sediment depths were found to range between 0.5 m to 2.6 m deep, with typical peat depths ranging between 30 cm – 100 cm of a dense organic layer in various stages of decomposition. The organic layer is underlain by grey sandy clay with clay content decreasing with depth (Figure 2). Sand and gravel was observed in the 10 cm to 30 cm range above bedrock.  Soil acidity was observed to be relatively uniform over depth with an average pH 5.7, however electrical conductivity and chloride decreased with depth; suggesting evapo-concentration of salts within the upper layers of the swamp. Soil moisture by weight and organic content were measured to decrease with depth, indicating decreasing porosity. Specific yield of swamp surface soils (0 m to 0.2 m) ranged between 15-20%, with deeper sediments (0.2 m to 0.4 m) approximately 10% greater.

Analysis of the water levels across the swamps, in conjunction with preliminary water balance modelling, indicates that despite the current data collection program, significant degrees of freedom remain unaccounted. Key factors such as transpiration, runoff, infiltration, interflow and groundwater losses are currently unknown and present seven sources of uncertainty within the water balance model. To reduce the uncertainty and close the water balance of peat swamps, further long term monitoring and site specific measurements are required. With the addition of soil core samples, soil hydraulic conductivity, long term water level data and further swamp geometry data, eight out of a total of nine water balance quantities will be known for the swamp, enabling increased reliability to assess the impacts of climate change, changes in land use, and undermining on long-term swamp ecology.  The findings from this study provide fundamental information that forms the basis for ongoing investigations critical for understanding peat swamp hydrology.

Figure 2: Typical swamp lithology

Figure 2: Typical swamp lithology

Acknowledgements. This research was funded through the Temperate Highland Peat Swamps on Sandstone Research Program (THPSS Research Program). This Program was funded through an enforceable undertaking as per section 486A of the Environment Protection and Biodiversity Conservation Act 1999 between the Minister for the Environment, Springvale Coal Pty Ltd and Centennial Angus Place Pty Ltd.  Further information on the enforceable undertaking and the terms of the THPSS Research Program can be found at www.environment.gov.au/news/2011/10/21/centennial-coal-fund-145-million-research-program.

Contact. William C Glamore and Duncan S Rayner, Water Research Laboratory, School of Civil and Environmental Engineering, UNSW Australia (110 King St, Manly Vale, NSW 2093, Australia, Tel: +61/ 2 8071 9868. Email: w.glamore@wrl.unsw.edu.au ).

Conservation of an endangered swamp lizard

Key words:         Eulamprus leuraensis, fire impacts, disturbance ecology, habitat requirements, Scincidae

The Blue Mountains Water Skink is known from less than 60 isolated swamps in the Blue Mountains and Newnes Plateau of southeastern Australia (Fig 1). Understanding the species’ ecology, notably its vulnerability to threatening processes such as fire and hydrological disturbance, is essential if we are to retain viable populations of this endangered reptile.

Fig 1. Swamps containing Eulamprus leuraensis used in our baseline surveys (from Gorissen et al., 2015)

Fig 1. Swamps containing Eulamprus leuraensis used in our baseline surveys (from Gorissen et al., 2015)

Design: We surveyed swamps across the species’ known range to identify critical habitat requirements, and to examine responses both of habitat features (vegetation) and lizard populations to fire regimes and other anthropogenic disturbances. Our analyses of fire impacts included both detailed studies post-fire, and GIS-based analyses of correlations between lizard abundance and fire history.

Results to date: Blue Mountains Water Skinks appear to persist wherever suitable swamp habitat is maintained, although lizard numbers decline after frequent fires, hydrological disturbance or urbanization. However, the lizards (especially, adults) rarely venture out from the core swamp habitat into the surrounding woodland matrix. The “fast” life-history of this species (rapid growth, early maturation, high reproductive output) enables populations to recover from local disturbances, but very low vagility means that re-colonisation of a swamp after extirpation of a population is likely to be very slow (if it occurs at all).

Fig 2. Blue Mountains Water Skink within its swamp habitat (Photo: S. Dubey)

Fig 2. Blue Mountains Water Skink within its swamp habitat (Photo: S. Dubey)

Fig 3. Sarsha Gorissen checks a trap for lizards in a Newnes Plateau swamp (Photo: N. Belmer)

Fig 3. Sarsha Gorissen checks a trap for lizards in a Newnes Plateau swamp (Photo: N. Belmer)

Lessons learned and future directions: The suitability of a montane swamp for Blue Mountains Water Skinks can be readily assessed from soil-moisture levels and vegetation characteristics. Effective conservation of this endangered reptile species should focus on conserving habitat quality in swamps, rather than targeting the lizards themselves. If healthy swamps can be maintained, the lizards are unlikely to face extinction. Given high levels of genetic divergence among lizard populations (even from adjacent swamps), we need to maintain as many swamps as possible.

Stakeholders and Funding bodies: This research was funded through the Temperate Highland Peat Swamps on Sandstone Research Program (THPSS Research Program). This Program was funded through an enforceable undertaking as per section 486A of the Environment Protection and Biodiversity Conservation Act 1999 between the Minister for the Environment, Springvale Coal Pty Ltd and Centennial Angus Place Pty Ltd.  Further information on the enforceable undertaking and the terms of the THPSS Research Program can be found at www.environment.gov.au/news/2011/10/21/centennial-coal-fund-145-million-research-program.

Contact information: Prof Richard Shine, School of Life and Environmental Sciences, Heydon-Laurence Building A08, University of Sydney, NSW 2006 Australia. Phone: (61) 2-9351-3772; Email: rick.shine@sydney.edu.au

The spatial distribution and physical characteristics of Temperate Highland Peat Swamps on Sandstone (THPSS)

Key words: wetlands, upland swamp, geomorphology, mapping, Sydney Basin

Effective conservation and management of natural resources requires that we have an understanding of the spatial distribution and physical characteristics of the systems of concern. The results of the THPSS mapping project summarised here provide an essential physical (geomorphological) template atop which a range of other biophysical information on swamp structure, function and condition can be collated and interpreted.

Design. Using a 25 m Digital Elevation Modal (DEM) coupled with orthorectified aerial photography, the THPSS of the Sydney Basin were mapped in ArcGIS. Only valley-bottom swamps were mapped. Hanging swamps or hillslope drapes were excluded. In ArcGIS, the physical attributes of the swamps were attributed and measured. This included swamp area, elevation above sea level, swamp slope, catchment area, swamp and catchment elongation ratio, swamp length and distance to coast.

Figure 1: Regions in which THPSS occur in the Sydney Basin

Figure 1: Regions in which THPSS occur in the Sydney Basin

Results. Five regions of THPSS were mapped (Figure 1); Newnes (Figure 2), Blue Mountains (Figure 3), Budderoo (Figure 4), Woronora (Figure 5) and Gosford (Figure 6). Across these regions there is a total of 3208 individual THPSS. The combined area of these swamps is 101 km2 (10,100 ha) and the combined catchment areas that contain them cover 789 km2. They occur at a median distance of 57 km from the coast, but this is highly varied, ranging from 0.4 – 96 km.

The swamps occur in areas with an average annual rainfall of 1505 mm/year and average annual temperature is 15oC. They occur at a wide range of elevations. Those closer to the coast occur on elevations as low as 160 m ASL, and those further from the coast on plateau country can occur at elevations up to 1172 m ASL. The bulk of these systems occur at median elevations of 634 m ASL. The swamps are elongate in shape, having a median elongation ratio of 0.46. This makes the majority of these systems relatively long (median length is 216 m) and narrow. They occur in relatively elongate catchments with median elongation ratios of 0.61 and median catchment lengths of 488 m. Almost all these valleys terminate at their downstream ends at a valley constriction or bedrock step, making the valleys ‘funnel-shaped’.

Catchment areas draining into the swamps are, on average, 0.25 km2. This means these systems tend to occur in the very headwaters of most catchments in first or second order drainage lines. Each swamp is, on average, 31,537 m2 in area (3.1 ha). These swamps form on deceptively steep slopes. Median minimum swamp slope is 6.2%. The funnel-shaped valleys produce effective constrictions behind which alluvial materials and peat can accumulate, resulting in valley fills forming on relatively steep slopes.

 Stakeholders and Funding bodies. This research was funded through the Temperate Highland Peat Swamps on Sandstone Research Program (THPSS Research Program). This Program was funded through an enforceable undertaking as per section 486A of the Environment Protection and Biodiversity Conservation Act 1999 between the Minister for the Environment, Springvale Coal Pty Ltd and Centennial Angus Place Pty Ltd.  Further information on the enforceable undertaking and the terms of the THPSS Research Program can be found at www.environment.gov.au/news/2011/10/21/centennial-coal-fund-145-million-research-program. This project was also partly funded by an ARC Linkage Grant (LP130100120) awarded to A/Prof. Kirstie Fryirs and A/Prof. Grant Hose at Macquarie University. We thank Will Farebrother for working on this project. We thank the NSW Land and Property Information for the orthorectified aerial photographs that are used under a research-only license agreement.

Contact information. A/Prof. Kirstie Fryirs, Department of Environmental Sciences, Macquarie University, North Ryde, NSW 2109; +61298508367; kirstie.fryirs@mq.edu.au  A/Prof. Grant Hose, Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109; +61298508367; grant.hose@mq.edu.au

Figure 2: THPSS of the Newnes region

Figure 2: THPSS of the Newnes region

Figure 3: THPSS of the Blue Mountains region

Figure 3: THPSS of the Blue Mountains region

Figure 4: THPSS of the Budderoo region

Figure 4: THPSS of the Budderoo region

Figure 5: THPSS of the Woronora region

Figure 5: THPSS of the Woronora region

Fig 6 - Gosford swamps map

Figure 6: THPSS of the Gosford region

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

Penrhyn Estuary Habitat Enhancement Plan: Habitat Rehabilitation for Migratory Shorebirds in Botany Bay, NSW

Peggy O’Donnell

Keywords: estuarine, restoration, saltmarsh, seagrass, roosting habitat, feeding habitat

Introduction: The Penrhyn Estuary Habitat Enhancement Plan (PEHEP) is an ambitious rehabilitation project undertaken to compensate for habitat loss due to the expansion of Port Botany. Development in Botany Bay, NSW, has caused substantial biophysical changes since the 1940s. Shorebird habitat has decreased due to airport development and expansion and Foreshore Beach is greatly reduced. Penrhyn Estuary is the only remaining significant shorebird roosting and feeding habitat along the northern shoreline but has legacy pollution. The PEHEP was prepared as part of development approval and implemented from 2012 to 2017.

Figure 1: Penrhyn Estuary 2008, before port expansion.

Figure 1: Penrhyn Estuary 2008, before port expansion.

Figure 2: Penrhyn Estuary 2015, four years after port expansion works.

Figure 2: Penrhyn Estuary 2015, four years after port expansion works.

Broad aims and works: The PEHEP aims to rehabilitate the estuary by expanding roosting and feeding grounds for migratory shorebirds and thereby increase their populations in line with Australia’s international responsibilities for shorebird conservation. Key works included levelling of sand dunes to create saltmarsh habitat and expansion of existing intertidal sand flats by filling deeper parts of the estuary with dune sand. A flushing channel was constructed to ensure adequate tidal exchange and to provide habitat suitable for seagrass beds. Protected seagrass, Strapweed (Posidonia australis) was transplanted prior to works and remaining Eelgrass (Zostera capricorni) and Paddleweed (Halophila ovalis) were protected from damage during construction using silt curtains. Local saltmarsh species planted were optimal for use as roosting habitat and extensive weed removal and maintenance was undertaken. Sound barriers, lighting and fencing around the estuary and port structure were designed to favour shorebirds and deter predators.

Monitoring programs compared baseline and post-rehabilitation conditions to assess rehabilitation efficacy. Surveys were done within the estuary and at appropriate reference locations within a BACI experimental design framework. Indicators included: abundance of key shorebird species, benthic infaunal communities, planted and transplanted saltmarsh, remnant and transplanted seagrasses off Foreshore Beach, and water quality.

Results to date:

Water Quality. Four years after habitat enhancement, physiochemical properties (temperature, pH, dissolved oxygen, salinity, total suspended solids, key nutrients) and a productivity indicator (chlorophyll a) were not significantly different from pre-construction or reference values. The configuration of the flushing channel simulated modelled estuary flushing times No algal blooms have been identified to date, suggesting the absence of eutrophic conditions within the now shallower estuary.

Saltmarsh habitat. After planting propagules the total area of saltmarsh habitat in Penrhyn Estuary exceeds 40,000 m2, a 76% increase post port construction and habitat creation (see Sainty 2016 and Dalby-Ball & Olsen 2016 for details of saltmarsh design and planting methodology). Following the works, saltmarsh species diversity, abundance and condition all improved.

The newly-planted saltmarsh vegetation appeared healthy showing continued growth with variability mainly at the margins of planted beds. The main roosting habitat species Salt Couch (Sporobolus virginicus) increased in all treatments, while Seablight (Suaeda australis) decreased slightly consistent with its removal in strategic locations to maintain plant height favourable for shorebird roosting habitat. The ecological function of planted saltmarsh areas was similar to that at reference locations (including other constructed saltmarsh habitats) and a trend of increasing biodiversity was observed throughout the three post-rehabilitation surveys. Some habitats treatments have not responded as well, including those transplanted prior to enhancement works and areas that were cleared of mangroves and weeds. Overall, the majority of ecological targets set with respect to the saltmarsh vegetation within Penrhyn Estuary were met.

Benthic intertidal habitat. Unvegetated intertidal feeding habitat for migratory shorebirds increased by 307% as a result of filling deeper parts of the estuary with dune sand. To enhance invertebrate abundance and diversity, dune sand was augmented with seagrass wrack and river mud as it was profiled in the estuary. Earthworks were staged such that tidal exchange with Botany Bay was altered and/or restricted but never eliminated during the two year construction period.

Criteria for the success of habitat creation were derived from comparison to target values based on pre-enhancement surveys and reference locations. Physical indicators were median grain size and percentage of fine sediments (% clay and silt fractions). Biological indicators were invertebrate abundance and biomass.

After habitat enhancement targets for invertebrate biomass were exceeded, but were not significantly different to those at reference locations. Invertebrate abundance reached only 61% of the target value and decreases resembled those in reference locations. Median grain size and percentage fines in newly created sand habitats were similar to pre-enhancement levels.

The taxonomic composition of benthic assemblages shifted post enhancement. Polychaete worms were characteristic of the assemblage before enhancement while gastropods and bivalve molluscs drove assemblage patterns after enhancement. Polychaetes declined from 76% of all invertebrates before enhancement to 47% after, while molluscs increased from 16% before to 49% after.

Seagrass habitat. Prior to construction, seagrasses off Foreshore Beach had undergone a significant natural decline. Strapweed patches within the footprint of the new boat ramp were transplanted to southern Botany Bay and are now indistinguishable from local plants. Condition of remaining seagrass patches off Foreshore Beach was monitored as was recolonization in the created flushing channel and lower reaches of the estuary.

Three post–construction monitoring surveys have documented a narrow, large bed of Paddleweed containing small patches of Eelgrass and Strapweed that extends off Foreshore Beach in 2-3 m water depth. Small isolated patches of Eelgrass and Strapweed persist at Foreshore Beach. Post-construction conditions are suitable for their survival and larger seagrass beds may be able to re-establish given normal processes of succession. Although numerous patches of the colonising Paddleweed and Eelgrass have been recorded in the flushing channel and in the inner estuary, typically these have not persisted. Turbidity may be limiting light penetration to the deeper parts of the flushing channel and offshore movement of sediments may be smothering seagrasses in the shallower areas of the flushing channel before they can fully establish.

Shorebird populations. Six key species of shorebirds were selected to indicate the success of the rehabilitation project: Bar-tailed Godwit (Lamosa lapponica), Red-necked Stint (Calidris ruficollis), Double-banded Plover (Charadrius bicinctus), Curlew Sandpiper (Calidris ferruginea), Red Knot (Calidris canutus) and Pacific Golden Plover (Pluvialis fulva). Abundance, diversity, health and habitat usage were monitored for these species and compared to target numbers derived from pre-construction data in 2006, as well as counts at reference sites. The frequency and sources of disturbance and observations on predation were recorded in peak and off-peak seasons.

The population of Pacific Golden Plover appears to be responding positively to the works, with the target exceeded in five consecutive seasons. Mean numbers of Double-banded Plover have increased at Penrhyn Estuary throughout both tidal phases, though is yet to meet its target peak count. Bar-tailed Godwit and Red-necked Stint have declined in this period, and there were no sightings of Red Knot or Curlew Sandpiper in the 2015 peak season surveys.

Disturbances to shorebirds in Penrhyn Estuary have been reduced with the completion of the sound barrier around the port side perimeter and exclusion of the public. Predation was high in the peak 2014 season, emphasising the need to control foxes and cats.

Monitoring reports for the PEHEP are available at:

http://www.sydneyports.com.au/sustainability/penrhyn_estuary_rehabilitation/monitoring_and_reporting2

Lessons learned and future directions:

  • Achievement of the desired profile for the site based on modelling and watering of saltmarsh plants in the initial stages likely set the stage for the success in establishing the large tracts of saltmarsh habitat. The initial removal and subsequent maintenance of a mangrove-free estuary, including a floating trash boom is supporting regular weed removal to improve the chances of long-term sustainability.
  • The relatively poorer response of transplanted saltmarsh areas, and those weeded but otherwise undisturbed suggests that for large habitat creation projects, propagating and planting local saltmarsh species is an efficient, appropriate approach the showed good results in the short term.
  • Earth moving works were staged such that the tidal exchange within the inner estuary was never completely blocked. This is likely to be a factor in the rapid reestablishment of benthic invertebrates, whose pattern of succession and composition differs from those reported for similar projects. Together with the improvement of dune sand by the addition of seagrass wrack and river mud, the fundamentals for a sustainable feeding habitat for shorebirds have been laid.
  • Tidal erosion removed a small portion of saltmarsh habitat along the inner estuary margin which was reshaped and repaired without further habitat damage or disturbance to roosting birds. The lesson: despite careful planning, erosive forces can alter habitats unpredictably as created habitats mature, and timely adaptive management is required to rectify damage and reduce further loss.
  • Shorebird populations and invertebrate abundance in the first two years of post-construction monitoring showed a generally positive correlation and similar trajectories of, suggesting that created intertidal habitat provided sufficient prey items to support increased shorebird populations in the longer term, despite considerable variability and failure of both populations to meet some target indicators. The abundance, biomass and community composition of benthic invertebrates in the most recent sampling (November 2014) fell within the range of variation seen in the five previous sampling events, however overall shorebird abundance fell to a minimum. Shorebird observations for the three months up to March 2015 showed an increasing trend, however targets for all but one species (Pacific Golden Plover) have not been achieved.

Comparisons to data from reference locations suggest that some factors may be operating at a range of spatial scales observable along the east coast of Australia. For all but Bar-tailed Godwit they suggest an overall decrease in key migratory species that is not limited to Penrhyn Estuary. Predation (or displacement due to presence of predators) may reduce the population of some shorebirds at some times, but no observations suggest that habitat quality, including roosting habitat and availability of prey items deter or limit the level of shorebird habitat use in Penrhyn Estuary.

Stakeholders and Funding bodies: Port Authority of NSW (Formerly Sydney Ports Corporation) fund and manage all aspects of the project, beginning with EIS studies and construction through to ongoing maintenance and monitoring. NSW Ports provides funding for ongoing maintenance and monitoring. Shorebird monitoring was done by as subcontract to Cardno (NSW/ACT) by Avifauna Research & Services, Email www.avifaunaresearch.com.au

Contact information: Dr Peggy O’Donnell Practice Lead Ecology, Water & Environment, Cardno (NSW/ACT). Tel: +61 2 9496 7700 Mobile +61 422 858 827. Postal PO Box 19, St Leonards NSW 1590. Email peggy.odonnell@cardno.com.au

WATCH VIDEO: Peggy O’Donnell 2014 pesentation to AABR seminar

Restoring Sydney’s underwater forests: Crayweed transplant success

Ezequiel M. Marzinelli, Alexandra H. Campbell, Adriana Vergés, Melinda A. Coleman and Peter D. Steinberg

Key words: Seaweeds, coastal biodiversity, kelp ecosystems, Phyllospora comosa, Crayweed

Introduction: Seaweeds are major habitat-forming organisms that support diverse communities and underpin ecosystem functions and services along temperate coastlines globally. Key species of seaweeds are, however, declining and while conservation in a preventative sense is a partial solution to the challenge of habitat degradation, the status of many of the world’s ecosystems clearly demonstrates that conservation, alone, is not sufficient. Crayweed (Phyllospora comosa) is a large habitat-forming seaweed that forms extensive underwater forests on shallow rocky reefs throughout south-eastern Australia, supporting unique diversity and economically important species such as crayfish (Sagmariasus, Jasus) and abalone (Haliotis). However, Crayweed went locally extinct from around 70 km of Sydney’s coastline in the 1980s, coincident with peaks in heavy sewage discharges; and, despite subsequent significant improvements in water quality, it has not reestablished naturally (Coleman et al. 2008).

The overall aim of this ongoing project is to restore Crayweed forests to the Sydney metropolitan coastline. In this case study, our specific aims were to determine (i) whether this species supports different biodiversity than other similar extant habitat-forming seaweeds – thus providing a rationale for restoration – and (ii) whether restoring this species and its associated biodiversity would be feasible; that is, could we achieve levels of survival, recruitment and diversity similar to those in reference locations where this species still occurs.

Works undertaken:

Surveys. We compared biodiversity (densities of abalone, communities of fish and epifauna) associated with crayweed and two major habitat-forming seaweeds in NSW, the kelp Ecklonia radiata and the fucoid Sargassum vestitum, and barren habitats.

Transplanting. We transplanted Crayweed from extant populations north and south of Sydney into three Sydney reefs where Crayweed was once abundant, creating 1 – 4 replicate patches ranging from 5 – 20 m2 in each site, with densities of 15-20 per m2, which are within the range of patch-sizes and densities in natural populations (Fig 1).

Figure 1. A 20m2 Crayweed restoration patch being set up by divers.

Figure 1. A 20m2 Crayweed restoration patch being set up by divers.

Results to date: The surveys of extant Crayweed found that it supported much higher numbers of abalone and different communities of associated epifauna than other similar, extant habitat-forming seaweed species or barren habitats (Marzinelli et al. 2014; Marzinelli et al. 2016).

The Crayweed we transplanted onto Sydney’s reefs generally survived (40-70%), grew (c. 60 cm, total length) and reproduced (5-12 recruits per 0.1 m2 after 1 year) (Fig 2) similarly to those in reference populations (Campbell et al. 2014). In some restored locations, these populations are apparently self-sustaining, with first generation progeny found over 200 m away from the initial transplanted patches.

Figure 2. Recruits growing next to the restoration patch (6 months after transplantation).

Figure 2. Recruits growing next to the restoration patch (6 months after transplantation).

Because the ultimate goal is not only to restore Crayweed but also the biodiversity it supports, we quantified several components of associated biodiversity in replicate ‘restored’, reference and control (non-restored) locations several times before and after the restoration efforts. Initial results on some of these components (e.g. epifauna) suggest that restoring associated biodiversity can indeed be achieved by restoring Crayweed, but to successfully restore all associated species is likely to be a complex and long-term process (Marzinelli et al. 2016).

Lessons learned and future directions: Critical to success are (i) the significant improvement in water quality along the Sydney coastline in recent years, (ii) understanding the ecology and biology of this species, which has male and female adult plants that reproduce synchronously once stressed through the process of outplanting (osmotic stress and drying), and (iii) on a more practical level, minimizing the period between collection and outplanting, which should be done in the same day. In one of the sites, herbivory on the outplanted Crayweed limited restoration success, so we are now identifying the species responsible to guide site selection in future larger-scale restoration efforts.

Stakeholders and Funding bodies. This project is being carried out by researchers at the Sydney Institute of Marine Science & the Centre for Marine Bio-Innovation, University of New South Wales (EMM, AHC, AV, PDS), and NSW Fisheries (Department of Primary Industries; MAC). It is supported by the NSW Recreational Fishing Trust (DPI), the NSW Environmental Trust (OEH) and the Sea Life Trust.

Contact: Dr Ezequiel M. Marzinelli, Senior Research Fellow, Sydney Institute of Marine Science & Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia; Tel: +61(0)2 93858723; Email: e.marzinelli@unsw.edu.au

Saltmarsh translocation and construction, Penrhyn Estuary, Port Botany, NSW

Mia Dalby-Ball and Andre Olson

From June 2008 to June 2011, ecological restoration work was conducted by Port Authority of NSW in association with the expansion of the port at Port Botany, Sydney, NSW. The purpose was to expand and rehabilitate Penrhyn Estuary.

The saltmarsh works at Penrhyn Estuary involved 2.4 hectares being densely planted with saltmarsh species. In addition to this 3000m2 of saltmarsh was translocated within Penrhyn Estuary. The key driver for the saltmarsh design and plant selection was the requirement for the project to provide habitat for migratory wading birds.

There were many key aspects to the project. Primary among them was the engagement of an expert to undertake a pre-words evaluation and design the wetland construction. It was also important that planning involved representatives from different disciplines including those who would be doing the on-ground work and those monitoring migratory birds. Another key aspect was that approvals and licenses were identified and obtained early.

Saltmarsh construction. Seed collection (from local sources) and plant growing was carried out more than a year before plants were required. (This is because saltmarsh plants are slow to grow, there is a narrow window of time for seed collection and permits are required to collect seed or pieces.)

Implementation works first involved removal of dune weeds (Bitou-Bush, Chrysanthemum monilifera ssp. rotundifolia) and saltmarsh weeds, in particular Spiny Rush (Juncus acutus) of which large plants were hand removed and or cut and painted with herbicide. Germinating seedlings were irrigated with Saltwater. Monthly inspections undertaken with immediate removal of new plants.

This was followed by excavation of land so that it became inundated by monthly high tides. (Monitoring of tidal inundation was carried out to test that levels were appropriate and areas that had water pooling in excess of five days were filled.)

Soil conditioner (organic rich soil) was spread over the sandy substrate and mixed to 100mm, using cultivation equipment. This was followed by planting of over 250,000 saltmarsh plants including of Beaded Glasswort (Sarcocornia quinqueflora) and Salt Couch (Sporobolus virginicus). All saltmarsh plantings were irrigated with fresh water via a sprinkler system.

Fig 1. Translocating Beaded Glasswort via electric boat. (Photo: Dragonfly Environmental)

Fig 1. Translocating Beaded Glasswort via electric boat. (Photo: Dragonfly Environmental)

Translocation of saltmarsh. A 3000m2 area of Beaded Glasswort and Salt Couch was growing on an area that was to be excavated to become mudflats. This area was cut into ~ 20cm x 20cm blocks with 100mm deep soil and lifted by hand (shovels) and put onto wooden sheets (plywood) and transported to the recipient site. Transportation was chiefly by a small boat with electric motor (Fig 1).

The saltmarsh was translocated to the site where the Spiny Rush had been removed. At the recipient site it was planted into the substrate (Fig 2). Spaces between blocks were filled with soil from the donor site. The entire area was irrigated thoroughly with salt water. Irrigation continued for six months while the transplanted material established.

Monitoring. Monitoring existing saltmarsh and proposed saltmarsh creation sites prior to, during and for 2 years post works. Additional monitoring has been conducted for a further 3 years.

Fig 2. Transplanting clumps of Beaded Glasswort and Salt Couch into areas where Spiny Rush had been removed. (Photo: Dragonfly Environmental)

Fig 2. Transplanting clumps of Beaded Glasswort and Salt Couch into areas where Spiny Rush had been removed. (Photo: Dragonfly Environmental)

Fig 3. Sprinkler irrigation during saltmarsh planting. Fresh water irrigation continued for at least 6 months post-planting. (Photo: Dragonfly Environmental)

Fig 3. Sprinkler irrigation during saltmarsh planting. Fresh water irrigation continued for at least 6 months post-planting. (Photo: Dragonfly Environmental)

Lessons learned. At over 230,000 saltmarsh plantings, to our knowledge this is the largest recorded saltmarsh construction project recorded to date. A number of findings have resulted from the project, particularly our trials to arrive at a suitable growing medium for the plantings. We sought a soil that had free drainage good moisture retention properties and contained available nutrients. Fertiliser tablets alone are insufficient in sandy soils. We trialed a range of soil conditioners, with the most successful having high organic content and did not float. Irrigation is required as tidal inundation is not adequate to keep soil moist for seedlings. We found that irrigation was required for at least 6 months

Acknowledgements: Design and pre-works site evaluation was conducted by Geoff Sainty of Sainty and Associates and BioAnalysis.  Implementation and monitoring of saltmarsh during construction and establishment phase (two years monitoring) was carried out by Dragonfly Environmental.  Cardno (NSW/ACT) has been conducting environmental monitoring post establishment phase.

Contact: Mia Dalby-Ball, Ecological Consultants Australia, 30 Palmgrove Road,  Avalon NSW 2107, Australia (Tel: 0488 481 929; Email: ecologicalca@outlook.com) or Andre Olson, Dragonfly Environmental, 1/33 Avalon Parade, Avalon NSW 2107 Australia (andre@dfe.net.au).

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.

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

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