Category Archives: Grassland/grassy understorey

Brush pack experiment in restoration: How small changes can avoid leakage of resources and underpin larger scale improvements for restoration and rehabilitation

David Tongway and John Ludwig

Key words: Landscape Function Analysis, biological foci, water harvesting, desertification, erosion

The following experiment illustrates how relatively small changes to redirect water flow can capture water and other biological resources at a restoration site. However the process occurs not only at the micro scale but cumulates to site and landscape scales, making it a primary underpinning principles of a method of site analysis, Landscape Function Analysis (LFA) that has been applied across Australia and other countries to assist land managers counter desertification by redesigning processes that regulate the flow of resources, minimise losses and foster cycling. See http://members.iinet.net.au/~lfa_procedures/

The LFA mindset and methodology involve a purposeful change of focus from listing the biota/ species present or absent at a site, to an examination of the degree to which biophysical processes deal with vital resources with respect to stresses arising from management and climatic events.

Fig 1 before

Fig. 1. Before: bare, crusted, low OC soil, erosion, and high water runoff mainitained by low but persistent, set-stock grazing by sheep and kangaroos.

Fig 2. after treatment

Fig. 2. The restoration treatment was simply to build brush-packs across the contour to trap water, soil and plant litter, slowing overland outflow. This also prevented the grazing down to ~1cm. Grass plants were able to maintain about 10cm of photosynthetic tissue.

Fig 4

Fig 3. After 7 years. Clearly the soil properties have improved the ‘habitat quality’ for the target vegetation.

Fig 5 14 years after

Figure 4. After 14 years, native vegetation re-established.

Fig 3. detail of bushpack after 3 years.

Fig 5. Detail of the brushpack after 3 years showing micro-structures capable of slowing water and accumulating resources.

1. tongway table

ANOTHER KEY OBSERVATION RELEVANT TO RESTORATION AND REHABILITATION

Where resources are not captured or leak out of a system, patchiness will become evident as resources self-organise around foci of accumulation – creating ‘patches’ where resources accumulate and ‘interpatches’ from which they ‘leak’.

The Golden Rule for rehabilitation is: “Restore/replace missing or ineffective processes in the landscape in order to improve the soil habitat quality for desired biota.”

Fig 6. Grassy sward healthy

Fig. 6. A grassy sward patch where the grass plants are close enough together that the water run-off is unable to generate enough energy to redistribute the grassy litter, which is evenly distributed. (The slope is from top to bottom in the image.)

There is also no evidence of sediment transport (not visible in this image). This is because of the tortuous path and short inter-grass distance. It would be possible to derive the critical grass plant spacing for “sward” function in any landscape, taking into account slope, aspect and soil texture.

Fig 7. Grassland in patch-interpatch mode, due to exceeding the critical runoff length for erosion initiation. (Slope is from top to bottom.)

Note that litter and sediment have both been washed off the inter-patch and have been arrested by a down-slope grass patch. Note the orientation of the grassy litter strands.

 

 

 

 

 

 

 

 

 

 

 

 

Update on Regent Honeyeater Habitat Restoration Project (7 years on) – Lurg Hills, Victoria

Ray Thomas

Key words: Agricultural landscape, faunal recovery, community participation, seed production area

Twenty-one years of plantings in the Lurg Hills, Victoria, have seen a consolidation of the work described in the 2009 EMR feature Regent Honeyeater Habitat Restoration Project.  The priorities of the Project are to protect and restore remnants and enlarge them by add-on plantings. Together, this work has protected relatively healthy remnants by fencing; restored depleted remnants by planting or direct seeding; and revegetated open areas that had been cleared for agriculture. Other restoration activities include mistletoe removal, environmental weeding, environmental thinning; feral animal control, kangaroo reduction, nest box placement, and systematic monitoring of a range of threatened and declining woodland birds and hollow-dependent mammals.

Updated outputs since 2009. A further 540 ha of private land has now been planted (150 additional sites since 2009). This means the total area treated is now 1600ha on over 550 sites. The oldest plantings are now 19 years old and 10m high (compare to 12 years old and 6m high in 2009) (Fig 1).

The total number of seedlings planted is now approx. 620,000 seedlings compared with 385,000 in 2009. Some 280km fencing has been established compared with 190 km in 2009. Mistletoe now treated on scores of heavily infested sites

Foster's Dogleg Lane 19 yrs

Fig. 1. Ecosystem attributes developing in 19-year-old planting at Dogleg Lane (Foster’s). Note pasture grass weeds are gone, replaced by leaf litter, logs, understorey seedling recruitment, open soil areas.

Improvements in genetics and climate readiness. As reported in 2009, seed collection is carried out with regard for maximising the genetic spread of each species, to prevent inbreeding and more positively allow for evolution of the progeny as climate changes. This has meant collecting seed in neighbouring areas on similar geological terrain but deliberately widening the genetic base of our revegetation work. We are also attempting to create as broad bio-links as possible so that they are functional habitat in their own right (not just transit passages). This may allow wildlife to shift to moister areas as the country dries out. With a species richness of 35–40 plant species for each planting site, we also enable natural selection to shift the plant species dominance up or down slope as future soil moisture dictates.

2016 Update: In recent years we have engaged with geneticists from CSIRO Plant Division in Canberra, to improve the genetic health of our plantings. Many of our local plants that we assumed to be genetically healthy, have not recruited in our planting sites. For example, Common Everlasting (Chrysocephalum apiculatum) produces very little if any fertile seed each year because it is sterile to itself or its own progeny (Fig 2 video). In fragmented agricultural landscapes, it seems that many of our remnant plants have already become inbred, and it is seriously affecting fertility, form and vigor. The inbreeding level has affected fertility in this particular case, but we have several other cases where form and vigor are seriously affected as well.

Fig 2. Andie Guerin explaining the importance of collecting seed from larger populations. (Video)

Seed production area. We have now set up a seed production area (seed orchard) for about 30 local species that are ‘in trouble’, to ensure that the plants have sufficient genetic diversity to reproduce effectively and potentially adapt, should they need to as a result of a shifting climate. This will allow these populations to become self-sustaining. Each species is represented in the seed production area by propagules collected from typically10-15 different sites (up to 20kms and sometimes 50kms distant) and as many parents as we can find in each population.

We aim for at least 400 seedlings of each species, to ensure the genetic base is broad enough to have the potential for evolution in situ. The planting ratios are biased towards more from the bigger populations (that should have the best diversity), but deliberately include all the smaller populations to capture any unique genes they may have. We plant each population in separate parallel rows in the seed orchard to maximise the cross pollination and production of genetically diverse seed for future planting projects. We have noticed that the health of some of these varieties is greatly improving as a result of increasing the genetic diversity. On one site we direct-sowed Hoary Sunray, sourced from a large population, and it has since spread down the site very quickly (Fig 3).

Gary Bruce wildflower patch Orbweaver

Fig 3. Small sub-shrubs and herbaceous species are generally not planted in stage 1 of a project, as the weed levels are often too high for such small plants to succeed. These plants are only introduced in stage 2, when the weeds have diminished up to a decade later. This approach has been very successful with direct seeding and planting some of our rarer forbs.

Recruitment of Eucalypts now evident. Nearly 20 years on from the first plantings, we can report that quite a number of sites have eucalypts old enough to be flowering and seeding, and some of them are now recruiting. We are delighted that our early efforts to broaden the planting genetics are demonstrating success with such natural processes (Figs 1 and 3). Ironbark recruitment from our plantings commenced in 2014 and Red Box commenced in 2015.

Recruitment can also be seriously affected by herbivore problems, particularly rabbits. In recent years we have been undertaking careful assessments of rabbit load on a potential planting site and have gained some advantage by deploying an excavator with a ripper attached to the excavator arm. The excavator allows us to rip a warren right next to a tree trunk (in a radial direction), or work close to fence without damaging either. We’re finding this is providing a very good result. On one site we suspected there were a few warrens but it turned out to be just short of 30 warrens within 100 m of the site – each with 30-40 rabbit holes. After ripping all of those, we ended up with activity in only 2 of the warrens, which were then easily retreated.

We have had such good results with the rabbits on some sites that we are trialing planting without tree guards – it’s much more efficient on time, labour, and costs. And adjacent to bush areas, where kangaroos and wallabies are a significant threat to plantings, this process has an extra advantage. It seems that macropods learn that there is something tasty in the guards, so a guard actually attracts their attention. Our initial trials are producing some good results and given us confidence to expand our efforts with thorough rabbit control.

Faunal updates. An important objective of the project is to reinstate habitat on the more fertile soils favoured for agriculture, to create richer food resources for nectarivorous and hollow-dependent fauna including the Regent Honeyeater (Anthochaera phrygia). In 2009 the Regent Honeyeater was nationally Endangered and was thought to be reduced to around 1500 individuals. By 2015, it was thought to be reduced to 500 individuals, and so has been reclassified as Critically Endangered.

Regent Honeyeaters have turned up in recent years in gully areas where the soils are deeper, the moisture and nectar production is better, and there is a bit more density to provide cover against the effects of aggressive honeyeaters like the Noisy Miner (Manorina melanocephala). The Regent Honeyeaters have been able to remain on such sites for around for a week or more, but have not bred on the sites to date. But breeding has occurred about 15kms away on the eastern edge of our project area. Radio-tracking showed that these breeding birds were some of the captive-bred birds released at Chiltern 100km further NE, and that the birds came towards Lurg after the Chiltern Ironbarks had finished flowering. We consider it to be just a matter of time before the Regent Honeyeaters will find the many habitat sites we’ve planted on higher productivity soils in the Lurg area.

Formal monitoring of Grey-crowned Babbler (Pomatostomus temporalis temporalis) for the past last 13 years has documented a rapid rise (due to some wetter years) from 60 birds in 19 family groups to approx. 220 birds in 21 family groups. There is also exciting evidence that the endangered Brush-tailed Phascogale (Phascogale tapoatafa) is returning to the Lurg district. The distinctive shredded Stringybark nests are now found in scores of our next boxes (up to 10km from the site of our first records of 2 dead specimens in the south of our project area in the mid 1990s). This dramatic population spread is presumably a direct result of our carefully located corridor plantings that have bridged the habitat gaps all across the district.

Increased social engagement. In the last 6 years we have increased the number of visits to planting days by 50 per cent. There has been a steady growth in the number of new local landholders involved and the total number is now 160 landholders engaged, compared with 115 in 2009. Everyone we come across knows of the project and anyone new to the area hears about it from one of their neighbours. Very few people (you could count them on one hand), say they would rather not be involved. In fact we increasingly get cold calls from new people who have observed what has happened on their neighbour’s place and then phone us to say they want to be involved. It’s a positive indication that the project is part of the spirit of the area. This was further confirmed by the inclusion, of a very detailed Squirrel Glider (Petaurus norfolcensis) mural in a recent street art painting exhibition. The permanent artwork is the size of a house wall, and situated prominently in the heart of the parklands of Benalla.

Much of our work has relied heavily on volunteers, with a total of 10,344 students and 24,121 community volunteers involved over the past 21 years. City folk have fewer opportunities to be in nature, with the bushwalking clubs, university students and scouts in particular, really keen to come and roll up their sleeves.

Typically about 17 to 20 of the local schools, primary and secondary, help us with propagating the seedlings at the start of each year and then planting their own seedlings back out into the field in the winter and spring. And we are increasingly getting interest from metropolitan schools that come to the country for a week-long camp. Some of the schools even have their own permanent camps up here and they want to be involved with our hands on work too. “It’s simply part of our environmental responsibility”, is the way they express it.

Contact: Ray Thomas, Coordinator of the Regent Honeyeater Project Inc (PO Box 124, Benalla, Vic. 3672, Australia; Tel: +61 3 5761 1515. Email: ray@regenthoneater.org.au

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Seed production and direct seeding to restore grassy understorey diversity at Mount Annan, NSW.

Peter Cuneo, Jordan Scott and Katharine Catelotti

Key words: direct seeding, grassy woodland restoration, seed production areas, Cumberland Plain woodland

Need for restoring grassy diversity. The rapid spread of African Olive (Olea europaea ssp. cuspidata) in the Cumberland Plain region of western Sydney in recent decades is now a significant conservation concern (Figs 1 and 2). Cumberland Plain Woodland (CPW) is now listed at the state and federal level as a critically endangered ecological community, and African olive invasion is recognised as the greatest invasive threat to CPW, and listed under the NSW TSC Act as a Key Threatening Process.

Dense monocultures of African olive are now established at a landscape scale in western Sydney, and there has been considerable use of mechanical mulching (‘forest mowing’) to control these highly degraded CPW remnants/monocultures (Fig 3). Often only remnant trees remain, and once these dense olive infestations are controlled, land managers are faced with several years of follow up olive control, degraded native soil seedbank and a profusion of annual weeds.

The Australian Botanic Garden, Mount Annan (ABGMA) has completed over 40 hectares of mechanical control of African Olive since 2009. Recent research (Cuneo & Leishman 2015) has indicated that a ‘bottom up’ approach restoration using native grasses as an early successional stage has potential to restore these transitional landscapes and achieve a trajectory towards CPW.

Hillside African olive invasion

Fig 1. Hillside African Olive invasion

Beneath dense olive canopy

Fig 2. Nil biodiversity beneath dense African Olive canopy

Olive mulching machine

Fig 3.  Olive mulching machine

Like many landscape scale ecological restoration projects ABGMA faces a shortage of native grass seed, however a successful NSW Environmental Trust application provided the funding support to develop a 1500 sq metre native grass seed production area as part of the Australian PlantBank landscape. The key objective was to grow high quality weed free native grass seed (of known germinability) to direct sow on degraded African olive sites where the native grassy understory had been lost.

Seed production area. The seed production area was established by tubestock planting of four key local grasses, Dichelachne micrantha (Plume grass), Microlaena stipoides (Weeping meadow grass), Chloris truncata (Windmill grass) and Poa labillardieri (Tussock grass) (Figs 4 and 5). Seed was wild source collected from CPW and grasslands within ABGMA, which provides a reference vegetation type and condition to guide restoration. The seed production area which was irrigated and fenced to exclude rabbits was highly productive, even during the first summer season. Both hand and mechanical harvesting were used, and the total output over the 2014/15 summer was impressive 118 kg of seed material harvested. All seed batches were germination tested at PlantBank which indicated a total output of over 13 million viable seeds from the first harvest season.

Planting Seed prod area

Fig 4. Planting out seed production area

 

Plumegrass

Fig. 5.  Plumegrass in seed production area, almost ready for harvest

Direct seeding of grasses. Restoration challenges included large areas, profuse annual weeds and competitive olive seedlings on the transitional post-olive sites. A decision was made to focus the direct seeding across one fifth of the treatment area in a series of cultivated 2m wide strips at 8m spacing. The strips were created along contours to limit the erosive potential of the prepared areas. These seeded strips could then be managed in a similar way to surrounding cleared areas with broadleaf selective herbicide and slashing.

Seeded grass strips were prepared using a small track machine with surface tilling attachment to provide good soil/seed contact (Fig 6). Seed material (seed/stalks) were combined with compost (Fig 7) and sand and hand broadcasted. In an effort to create an ‘in situ’ seed production area and robust native grass populations, harvested grass seed was then used to high density (up to 3300 seeds/m²) direct sow a total of 5km x 2m wide strips throughout 5 hectares of cleared African olive sites at ABGMA in March 2015.

Favourable conditions during autumn 2015 resulted in excellent field germination, with established seedling densities of up to 608 seedlings/m² observed after 10 months (Fig 8). The combination of surface tilling and dense sowing rates has resulted in a dense and competitive grass layer, however some further broadleaf weed control along the strips will improve long term grass density and establishment.

These native grass strips will provide a ‘nucleus’ grass seed source for these degraded areas, maintaining soil stability, improving ecological resilience and accelerate the regeneration of these degraded areas.

Direct seeding strips

Fig 6. Direct seeding strips prepared

Mixing bulk native grass seed

Fig 7. Mixing bulk native grass seed

Seed strip established2comp

Fig 8. Seed strip established after one year

Lessons learned. Using known quality seed and achieving seed/soil contact through surface tilling was important to success, as cleared olive areas have a heavy mulch layer which limits seed contact. The use of both C3 and C4 grasses in the direct seeding mix worked well and is recommended, particularly for autumn sowing where cool season C3 can establish a quick cover followed by C4 grass establishment in summer. Some mechanical wild grass seed harvesting is also done at ABGMA, however practitioners should be aware of the risk of grassy weed contamination. Overall the project was relatively labour intensive, but some mechanisation of seed spreading could be achieved with a compost spreader. Steep terrain at ABGMA is a limiting factor for some machinery, and hand broadcasting can be a practical option.

Future directions would include scaling up the size of seed production areas, and refining mechanical harvesting techniques. Grass seed strips will be progressively managed, and seed either mechanically harvested or slashed to spread seed across the site. Once grasses are well established, the next phase will include direct seeding of CPW shrubs and trees. The well prepared and presented seed production area with mass plantings of native grasses, attracted considerable visitor interest at ABGMA and became a focus for several practitioner field days on olive control and ecological restoration.

Acknowledgements: Implementation of this NSW Environmental Trust project has relied significantly on working with industry partners, Greening Australia (Paul Gibson-Roy, Samantha Craigie, Chris Macris), Cumberland Plain Seeds (Tim Berryman) and Australian Land & Fire Management (Tom McElroy) who have bought additional technical expertise as well as on-ground implementation.

Contact person: Dr Peter Cuneo, Manager Seedbank & Restoration Research, Australian Botanic Garden, Mount Annan, NSW Australia. Locked Bag 6002, Mount Annan NSW, 2567. Email: peter.cuneo@rbgsyd.nsw.gov.au   Phone: +61 (2)46347915

Watch RegenTV Video : Seed production area

Read full EMR feature: http://onlinelibrary.wiley.com/enhanced/doi/10.1111/emr.12139

BG & CP website: https://www.rbgsyd.nsw.gov.au/Science-Conservation/Our-Work-Discoveries/Natural-Areas-Management/Restoring-test

 

 

Macquarie Island Pest Eradication Program – Impacts on vegetation and seabirds

Key Words: Subantarctic, eradication, seabirds, vegetation, restoration

Introduction. Introduced rabbits, rats and mice have caused widespread and severe ecological impacts on the native flora, fauna, geomorphology and natural landscape values of Subantarctic Macquarie Island. Major impacts include the destruction of almost half of the island’s tall tussock grassland and the depletion of keystone palatable species, a decline in the abundance and or breeding success of a range of seabird species due to habitat degradation, increased exposure to the elements and predation, as well as increased slope erosion. The Macquarie Island Pest Eradication Project is the largest eradication program for rabbits, ship rats and mice in the world.

The overall goal of the pest eradication project was to eradicate rabbits, rats and mice from Macquarie Island to enable restoration of the island’s natural ecological processes including the recovery of plant and animal communities impacted by these feral species.

Works undertaken. The Tasmania Parks and Wildlife Service developed a plan for the eradication of rabbits and rodents on Macquarie Island that was approved by the federal Minister of Environment in 2006. Following lengthy negotiations and a donation of $100,000 by the World Wildlife Fund (WWF) and Peregrine Adventures, funding of $24.6 million for the project was secured in June 2007 through a joint state and federal government agreement.

The three major components of the Macquarie Island Pest Eradication Plan after the initial planning and organisation phase were:

  • Toxic baiting of rabbits, rats and mice using aerial baiting from helicopters across the island conducted over two winters to minimise the risk of mortality for non-target seabirds. Mitigation measures were taken to reduce seabird mortality in six species after the 2010 baiting, including the introduction of calicivirus (Rabbit Haemorrhagic Disease Virus) before further baiting in May 2011 – (See Evaluation Report 2014)
  • On-ground follow-up with hunters and dogs, which was originally expected to take about three years but took seven months (2012) following the outstanding success of the calicivirus in substantially reducing rabbit numbers.
  • Five months after the last known rabbit was killed, the monitoring phase of the project commenced in April 2012 to search for any evidence of live rabbit or rodent presence on the island and continued for two years, with some 92,000 km travelled over 3 years (2011-2014).

Following two years of monitoring without any evidence of the target species, the project to eradicate rabbits and rodents from Macquarie Island was declared successful in April 2014.  A variety of established research/monitoring projects on threatened native plant species, invasive plant species, plant communities and ten species of seabirds on Macquarie Island have been used to provide biologic data on changes in abundance, distribution and condition (see Evaluation Report 2014).

Large areas of the highly palatable macquarie megadaisy are recovering from rabbit grazing Photo Kate Keifer

Figure 1. Large areas of the highly palatable macquarie megadaisy are recovering from rabbit grazing. (Photo Kate Keifer)

Results to date.

Vegetation. Vegetation recovery was well underway by 2013, when vegetation biomass on the island had increased by a factor of five to ten compared with 2011 levels.

The initial stage of vegetation recovery following rabbit eradication was a rapid increase in the biomass of the pre-existing communities. The pre-eradication vegetation was a highly modified disturbance disclimax with the majority of the lower slopes of the island dominated by Short Subantarctic Bent Grass (Agrostis magellanica), where regular soil disturbance by introduced species encouraged the establishment of herbaceous primary colonisers including willowherbs (Epilobium spp.), Subantarctic Bittercress (Cardamine corymbosa), Waterblinks (Montia fontana) and the introduced Annual Meadow Grass (Poa annua). Subantarctic Buzzy (Acaena magellanica) covered large areas. Tall Tussockgrass (Poa foliosa) was reduced to small pockets or individual plants on steep slopes, whilst the Macquarie Cabbage (Stilbocarpa polaris) was confined to very steep coastal slopes and Prickly Shieldfern (Polystichum vestitum) survived in exclosures.

More recent monitoring shows bare ground declining, with further increases in vegetation cover and successional changes. Taller/longer lived species have greatly reduced the cover of primary colonisers (mostly short lived, small herbs). The three introduced plant species on the island, all of which are primary colonisers, have fluctuated in abundance post-eradication.

Annual meadow grass has decreased markedly in abundance away from areas of seal and seabird disturbance, while Mouse-ear Chick Weed (Cerastium fontanum) and Garden Chickweed (Stellaria media) initially increased in abundance between 2011 and 2013 but have since declined.

The previously ubiquitous Subantarctic Buzzy has declined dramatically with competition from other species, while the previously less common Little Burr (Acaena minor) is now more prevalent.

The megaherbs Macquarie Cabbage and Macquarie Megadaisy (Pleurophyllum hookeri) and Tall Tussockgrass are beginning to spread and establish across the island (Figure 1). It is predicted that a combination of these species will become dominant in much of the coastal and slope vegetation over time, with Tall Tussockgrass already increasing in cover in many areas. The prickly shieldfern is expanding from a few remnant populations by recruitment or regeneration in former exclosures, as well as establishing in new locations.

Image 4 DSC_1110 cropped

Seabirds. A combined total of 2418 individual native birds were recorded as killed via primary and secondary ingestion of broadifacoum poison during the winter baiting of 2010 and 2011. These numbers are minima, since many were predated before detected and others died at sea. Kelp Gull (Larus dominicanus) sustained the largest mortality (n=989), followed by Giant Petrels (Macronectes spp; n=761), Subantarctic Skua (Catharacta skua) (n=512) and Black Duck (Anas superciliosa) (n=156). Existing monitoring programs enable the population consequences of this mortality to be evaluated for both species of giant petrel and for skua, however baseline data for gulls and ducks on Macquarie Island are lacking. The mortality event was associated with a 25-30% reduction in the breeding populations of both giant petrel species, however ongoing monitoring reassuringly shows both populations to have stabilised and appear to have resumed the increasing trajectory that they were undergoing before the mortality event. Skua were heavily impacted, with breeding numbers reduced by approximately 50% in monitored sites. There is minimal sign of recovery for this species in recent years. The response of this species to the sudden removal of a primary prey item (rabbits) and the consequent flow-on ecosystem impacts is the focus of current investigation.

With the success of Macquarie Island Pest Eradication Program, we are seeing rapid recovery in the breeding habitats of both burrow and surface nesting species. Grey Petrel (Procellaria cinerea), which re-established on Macquarie Island after the successful eradication of cats in 2000, have continued to increase and Blue Petrel (Halobaena cerulea) which were previously restricted to rat-free offshore rock-stacks, have returned to mainland Macquarie Island and continue to expand in both distribution and number. Dedicated survey effort in coming seasons will provide quantitative estimates of the response of the burrow nesting seabird assemblage to Macquarie Island Pest Eradication Program.

Lessons. Perhaps one of the most important lessons learned is the value of biological monitoring data, before during and after such an eradication program, which provides the basis for effective adaptive management as well as evaluation of success or otherwise.

The other salutatory lesson is the complex biological inter-relationships that exist and a need to more explicitly factor in the consequences of the ‘unknowns’ in associated risk assessments.

Acknowledgement. Thanks to Micah Visoiu for most recent vegetation data.

Contact. Jennie Whinam, Discipline of Geography & Spatial Sciences, University of Tasmania Jennie.Whinam@utas.edu.au; 0447 336160. Rachael Alderman, Wildlife Management Section, Department of Primary Industries, Parks, Wildlife and Environment, Rachael.Alderman@dpipwe.tas.gov.au

Fire as a tool in maintaining diversity and influencing vegetation structure – Grassy Groundcover Restoration Project

Paul Gibson-Roy

Greening Australia’s Grassy Groundcover Restoration Project commenced in 2004 to investigate the feasibility of restoration of grasslands and grassy woodlands (primarily by direct seeding) in the agricultural footprint of Australia. To date the project has achieved the reconstruction of grassy understories in grassland or grassy woodland on near to 100 sites in ex-agricultural land (predominantly across Victoria, but increasingly in southern to central New South Wales and mid-lands Tasmania). Post establishment we use fire in our sites to reduce biomass, particularly to inhibit grass growth which over time become the dominant life form, just like trees can in other communities. Opening the grass canopy allows for the small forbs and sub-dominant grasses to regenerate. Burning in particular can help create these canopy gaps and in a cost-effective way.

Fig 1. Snake Gully CFA burn at Chepstowe.

Fig 1. Snake Gully CFA burn at Chepstowe.

Fig 2. Restored herb-rich grassland on roadside near Wickliffe.

Fig 2. Restored herb-rich grassland on roadside near Wickliffe.

Fig 3. Differential management of Kangaroo Grass at Rokewood Cemetery.

Fig 3. Differential management of Kangaroo Grass at Rokewood Cemetery.

Operational challenges can and often do arise considering sites are located within urban or agricultural footprints where protection of life and property is paramount. This at times prompts us to consider alternative methods of biomass removal such as through grazing (sometimes used as a method for annual weed control) and mowing when burning is deemed inappropriate. These alternative or complimentary biomass reduction methods can also have additional benefits. For example, mowing and producing bales of cut straw, if cut in early spring or autumn, can be used for fodder. This is also the case with grazing. Alternatively, if sites are cut and baled in late spring or summer when grasses contain ripe seed, the hay can be moved and spread at other locations to create a grassland elsewhere.

While the project has carried out various combinations of these approaches at our restored grasslands in recent years, the following list includes a few examples of their use.

  1. Burning at Chepstowe (located to the west of Ballarat, Victoria) to reduce grass biomass and allow forbs to establish and persist. The burn is being conducted by Snake Gully CFA members (Figure 1).
  2. The nationally threatened species – Hoary Sunray (Leucochrysum albicans tricolor) and Button Wrinklewort (Rutidosis leptorrynchoides) were introduced by direct seeding along with many other ground layer species onto a roadside near Wickliffe, Victoria. Following establishment the grassland has been managed with fire by the Wickliffe CFA so that grasses do not dominate and the rare species can recruit and spread. (Figure 2.)
  3. Kangaroo Grass (Themeda triandra) growth has been the focus of differing management techniques within the Rokewood cemetery reserve Victoria (under the Cemetery Trusts grassland management plan). This remnant grassland contains the largest Victorian population of the nationally threatened Button Wrinklewort. To avoid the Kangaroo grass dominating the herb rich areas, it is maintained by fire, whereas in the approaches to the burial area it is kept mown low for function and protection of the memorial infrastructure. (Figure 3).
  4. Similar opening of a restored grassy canopy is achieved at Chatsworth in south western Victoria where a grassland currently dominated by Wallaby Grass (Rytidosperma setaceum) was mown and baled (Figures 4 and 5). This material was used to as fodder by the landholder.
  5. A late autumn burning of herb-rich restored grassland at Hamilton, Victoria, undertaken by the Buckley Swamp CFA (Figure 6).
  6. The aforementioned site at Hamilton taken in the following spring. It shows visitors touring the restoration where Common Everlasting (Chrysocephalum apiculatum) and many other sub-dominant forb species are in full bloom (Figure 7).
  7. Diverse restored grassland located adjacent to a wheat crop at Point Henry, near Geelong, Victoria. This site 16 ha site has been maintained over time by combinations of burning and cutting and baling (Figure 8).
Fig 4. Wallaby grass dominated grassland at Chatsworth pre-baling.

Fig 4. Wallaby grass dominated grassland at Chatsworth pre-baling.

Fig 5. Wallaby grass dominated grassland at Chatsworth post-baling.

Fig 5. Wallaby grass dominated grassland at Chatsworth post-baling.

Fig 6. Buckley Swamp CFA conducting a late autumn burn of restored herb-rich grassland near Hamilton.

Fig 6. Buckley Swamp CFA conducting a late autumn burn of restored herb-rich grassland near Hamilton.

Deciding which method or combination of biomass removal techniques to use, and at what time can be complex and there is no textbook. Good management is about constantly assessing the landscape and prevailing conditions to identify prompts for action. It is also about having the right networks and technical capacity available when required. As a general rule we find that when a site has greater than 70% vegetation cover of the ground surface and dry material is being held above 150 mm, there is enough combustible material to carry a flame. This condition also indicates that that the gaps in the vegetation are starting to close up.

Contact: (Dr) Paul Gibson-Roy. Lead Scientist, Greening Australia.Tel: +61 437591097. Email: PGibson-Roy@greeningaustralia.org.au

[This project summary is a precis of a talk presented to the Nature Conservation Council of NSW’s 10th Biennial Bushfire Conference, ‘Fire and Restoration: Working with Fire for Healthy Lands’ 26-27 May 2015. For full paper see: http://www.nature.org.au/healthy-ecosystems/bushfire-program/conferences/%5D

 Fig 7. Spring and wild flowers are in bloom at Hamilton.


Fig 7. Spring and wild flowers are in bloom at Hamilton.

Fig 8. Species and functionally diverse restored grassland adjoining a wheat crop near Geelong.

Fig 8. Species and functionally diverse restored grassland adjoining a wheat crop near Geelong.

Prescribed burning provides opportunities for site restoration via weed management in the Mount Lofty Ranges, South Australia

Andrew Sheath

Introduction. The purpose of much of the prescribed burning work we do in the Mount Lofty Ranges in South Australia fuel reduction to mitigate the risk of bushfire. But we also do a lot of work, including burning, purely for the purpose of biodiversity conservation. Being so close to Adelaide all of our Parks are highly fragmented and have a strong history of disturbance such as mining and grazing.

Within our team we have a very strong focus on weed control and we do this routinely for all of our burns. There are two reasons we have such a focus on weed management and no longer just go in and burn and walk away. The first is to ensure that the vegetation condition does not deteriorate and the second is to ensure that fuels don’t increase due to woody weeds. In many cases this is leading to improvements in quality of the sites.

Methods. Our burns are done under a prescription which specifies certain weather parameters for which the burn can be carried out safely. Our sites are typically between 5 and 200 hectares, often adjacent to built assets (Fig 1). Mapping both before a burn and 4 years after a burn allows us to monitor progress. We map most of our burns on foot, assessing native vegetation condition, weeds present, their distribution and their cover throughout the proposed burn site. We undertake this with a view to gaining a clear picture of what we’ve got to deal with during the burn and post-burn. Our planning begins 6-18 months prior to a burn to give us plenty of time to carry out works that are often seasonally dependent.

Fig 1: Example of a typical Adelaide Hills conservation area on the urban fringe. Red areas show prescribed burns either completed or in the planning phase.

Fig 1.  Example of a typical Adelaide Hills conservation area on the urban fringe. Red areas show prescribed burns either completed or in the planning phase.

Examples and results to date. In most of our situations pre-burn control greatly increases the efficiency of any post-burn work and overall makes our work easier.

Example 1: Figures 2 and 3, shows a significant reduction in the distribution of Gorse (Ulex europaeus) at an otherwise relatively intact site after the burn, improving the condition of the bush in this area.

Fig 2. Gorse distribution and density pre-burn

Fig 2. Gorse distribution and density pre-burn

Fig 3: Gorse distribution and density 3 years post burn after control work

Fig 3. Gorse distribution and density 3 years post burn after control work

Example 2: Figure 4 shows successful tree heath (Erica arborea) control in an otherwise intact woodland in the Adelaide hills. Six months prior to burning we cut and disturbed the stand of Tree Heath on this site to ensure all the biomass would burn; that we wouldn’t have the adults sitting up high above the flame dropping seed onto burnt ground (which often happens when burning under mild conditions); and, to promote juveniles which would then be burnt and killed during burn. The other benefits of this approach are that it also promotes native germination and makes follow up, post-burn easier.

Fig 4: Erica control site showing before being burnt or cut, after being cut and post burn.

Fig 4: Erica control site showing before being burnt or cut, after being cut and post burn.

Fig 5. Erica post control and pre-burn

Fig 5. Erica post control and pre-burn

Fig 6. Erica post-control and post-burn

Fig 6. Erica post-control and post-burn

Example 3: Figure 5 shows a perched swamp in the Adelaide Hills being thickly invaded by Wonnich (Callystachys lanceolata) from Western Australia. Because of location of the site we were unable to burn the swamp at sufficient intensity to consume the Wonnich. So in this situation we burnt the surrounding area in spring in mild conditions within prescription. We later went back in autumn after we had dropped all of the Wonnich on the ground and we burnt that swamp at a very high intensity and consumed all of the biomass. That promoted mass-germination of the weed. We’re then dealing with one age-class and we can go through and hand weed, spot spray, and re-burn areas to control the germination. Joe Quarmby, Threatened Flora Ecologist, was the mastermind behind this burn and continues to drive follow up control work at the site.

Fig 7. Swamp burnt in drier conditions during autumn.

Fig 7. Swamp burnt in drier conditions during autumn (after surrounding area burnt in more mild conditions in an earlier season).

Follow up control work in swamp.

Fig. 8. Follow up control work in swamp.

Lessons learned. Burning can be a very useful tool for weed management and although no site is ever the same we have been able to use a variety of techniques for certain weeds which greatly increase our efficiency. The key point however is that weed control should be and is routine and needs to be thought about pre-burn.

Acknowledgements. Thanks is extended to Joe Quarmby, Threatened Flora Ecologist.

Contact: Andrew Sheath, Department of Environment Water and Natural Resources – South Australia. Tel: +61 0457 512 032, Email: Andrew.Sheath@sa.gov.au

[This project summary is a precis of a talk presented to the Nature Conservation Council of NSW’s 10th Biennial Bushfire Conference, ‘Fire and Restoration: Working with Fire for Healthy Lands’ 26-27 May 2015. For full paper see: http://www.nature.org.au/healthy-ecosystems/bushfire-program/conferences/%5D

Forested wetland regeneration project, The Gap Road Woodburn, NSW

Julie-Anne Coward

Contract bush regeneration works involving fire and weed management commenced in 2011 in 2.5 ha of endangered ecological coastal floodplain communities at the Cowards’ property on the Gap Road, Woodburn in northern NSW (Fig 1). An area of 7.19 ha of the 10ha property had been recently covenanted for conservation by new owners and 2 small grants were gained to convert the previous grazing property back to forested wetland. Remnant vegetation existed on the property and regrowth was already occurring, although extensive areas were dominated by exotic pasture grasses, particularly >1m high swathes of Setaria (Setaria sphacelata).

Works commenced with spraying of the weed with herbicide and regular follow up spot spraying of weed regrowth. However, because the dead Setaria thatch was taking a long time to break down (and high weed regeneration was likely) a burn was carried out to hasten the recovery responses to fit within the 3 year funding cycle. The works were monitored before and at 6 monthly intervals using 6 (9m2) quadrats in each of hot burn, cool burn and unburnt areas (Fig 1).

Fig 1. Works zones at the Gap Road wetland

Figure 1. Works zones at the Gap Road wetland – mapped in April 2013 where the quadrats were laid out. and data recorded prior to and at 6-monthly intervals after treatment.

Works undertaken. A 2-3m wide firebreak was cut around the burn area and a burn was conducted in dry conditions on Oct 19th 2012 (Fig 2) by the landholders, assisted by Minyumai Green Team and with the local fire brigade on standby. The fire burnt approximately 0.5 ha of the Setaria-dominated area, most of which had been previously sprayed (Fig 2).

Results. A more complete (and presumably hotter) burn was achieved in the sprayed areas (Figs 3 and 4). Setaria and Ragweed germinated prolifically, with a few natives and the site was virtually blanket sprayed with glylphosate. By the second follow up natives had started to regenerate so spot-spraying was used thereafter, taking care to protect the natives. Within 5 months quadrats in the sites that burned hotter achieved over 50% native cover, while the unburnt area achieved only half (25%) that cover. Both areas ultimately achieved similar recovery of natives, but markedly higher spot spraying inputs over longer time frames were needed in the unburnt areas compared to the hotter burn areas.

Over the three year contract, unexpectedly high and prolific regeneration occurred of 35 species of native forbs, sedges and grasses (germinating from buried seed banks) and 7 species trees and shrubs (largely from seed rain) (Fig 5). However, weed germination was also prolific, particularly in unburnt areas, and required at least monthly levels of continual suppression.

fig 2. The burn itself (Oct 17, 2015)

Figure 2. The burn itself (Oct 17, 2015)

Figure 3. Sprayed Setaria prior to the burn.

Figure 3. Sprayed Setaria prior to the burn.

Figure 3. Prolific native groundcover and tree regeneration 2 years after the burn and as a result of consistent spot spraying.

Figure 3. Prolific native groundcover and tree regeneration 2 years after the burn and as a result of consistent spot spraying.

Lessons learned. The proximity of remnant vegetation (within 100m) and intact soil profile was important to the native recovery. At least monthly weed control is essential and can achieve results on its own. However, the project involved substantial volunteer time as well as contract labour – and when labour was insufficient new weed populations formed in the disturbed areas that then required more intensive treatment to overcome. Comparing the demand for weed control in burnt and unburnt areas showed that the feasibility of weed control is very much reduced without the use of fire to flush out weed at the outset.

Acknowledgements: The project is dedicated to the memory of Murray Coward who helped initiate the project. Minyumai Green Team (Daniel Gomes, Justin Gomes, Chris Graves and Andrew Johnston) have kept the project on track over the years, with assistance from Tein McDonald. Thanks is due to the EnviTE team, particularly Virginia Seymour, for their work at the site in the first 18 months. The project is covenanted with the Nature Conservation Trust of NSW (NCT) and received some initial funding from NCT. It subsequently gained a $15K Private Land Conservation Grant (funded by Foundation for National Parks and Wildlife and managed through the NCT) and has now gained a second, similar grant to continue and expand the works.

Contact: Julie-Anne Coward, Gap Road Woodburn. Email: mjcets1@bigpond.com

Re-introducing burning to Themeda Headland Grassland EEC, Narooma, NSW.

Tom Dexter, Jackie Miles, Deb Lenson

Key Words: Fire management, threatened ecosystem, Kangaroo Grass, weed management, Themeda

Introduction: In 2012, Eurobodalla Shire Council commenced a project to preserve local stands of declining Themeda Headland Grassland on Council managed land on three small headlands north of Narooma, NSW. Themeda Grassland on Seacliffs and Coastal Headlands is an Endangered Ecological Community (EEC) that grows on higher fertility soils and is listed under the NSW Threatened Species Conservation Act 1995.

Burning was trialed at two of the three sites to test whether fire could improve the environmental integrity of these sites. This trial has potential implications for the much larger stands of this EEC in various conservation reserves scattered along the NSW coastline as there are many which are not currently actively managed.

The three sites were slashed annually until 2010. While the dominant grass, Kangaroo Grass (Themeda triandra) was still present on all sites, the sites exhibited some decline in Kangaroo Grass cover and vigour, with weed present on all three sites (Fig 1). Slashing had kept the headlands free from shrubs however windrows of slashed grass suppressed Kangaroo Grass and appeared to encourage weed invasion. One of the sites, which was left unburnt for logistic reasons, was initially in worse condition than the other two due to the presence of an old vehicle track and more extensive weed cover particularly from Kikuyu (Pennisetum clandestinum).

The intensity of a burn is likely to vary on a seasonal basis and is dependent on the build-up of dead thatch and the prevailing conditions on the day. There is basis to believe that the traditional aboriginal burning would have taken place in Autumn and would have been a relatively cool burn. The optimum time to burn when considering the constraints of weed invasion is early spring.

Fig 1. Mowing damage at Duesburys Beach headland

Fig 1. Lines of bare ground indicate the location of windrows of dead grass from a history of mowing at Duesburys Beach headland

Works undertaken: Two successive burns were conducted in early spring on 2 of the 3 headlands, in August 2013 and August 2014 (Fig 2). The burn in 2013 was hotter than the burn in 2014 due to a higher build up of Kangaroo Grass thatch prior to the burn.

Follow-up weed control was implemented after the burns as the fire created gaps between the grasses and allowed targeted chemical control minimizing off target damage to Kangaroo Grass and other native species.

Data were collected on three occasions using ten 1 x 1 m quadrats, established along a 50 m transect spaced at 5 m intervals (one of these for each headland). The initial baseline data were recorded in Nov 2012, prior to the spring burns, and in each successive summer (2013/14 and 2014/15) following the burns.

Fig 2. Dalmeny Headlands burn 2015

Fig 2. Typical burn on the headlands

Results to date: The burnt areas (Figs 3 and 4) showed a significant decrease of annual exotic grasses; especially of Quaking Grass (Briza maxima) and Rats Tail Fescue (Vulpia spp.). The burnt areas also showed vigorous Kangaroo Grass growth and moderate seed production of that species. Two native species -Dwarf Milkwort (Polygala japonica) and Matgrass (Hemarthria uncinata Fig 5) not recorded prior to treatment were found after treatment in the quadrats. The most abundant native forbs, Swamp Weed (Selliera radicans) and Indian Pennywort (Centella asiatica) have persisted on the quadrats but not increased (Fig 6). Some exotic forbs – e.g. Yellow Catsear (Hypochaeris radicata) and Scarlet Pimpernel (Anagallis arvensis) have taken advantage of the removal of grass biomass and have also increased, further future analysis will determine whether this increase will impact on the native forbs. Perhaps the most important finding is the Coast Banksia (Banksia integrifolia) seedlings were killed by the fire allowing the sites to remain grassland.

The unburnt headland continues to deteriorate, with ongoing evidence of continued senescense of Kangaroo Grass, no Kangaroo Grass seed production, and exotic plants continuing to replace Kangaroo Grass in parts of the site. Kikuyu is the main exotic species on this site and is responsible for continued suppression of the native components of the grassland. There is also evidence of shrub invasion beginning to occur. It is anticipated that this site will be burnt in spring 2015.

Fig 2. Duesburys Point just after fire, Sept 2013

Fig 3. Duesburys Point just after burning, Sept 2013

Fig 3. Same site 11 months later, Aug 2014

Fig 4. Same site 11 months later, Aug 2014

What we learned: Kangaroo Grass remains vigorous throughout the burnt sites. The results to date show annual burning to be generally beneficial to the herbaceous components and associated grasses of this EEC. There was a higher success of exotic annual grass control in the first year which is most likely attributed to a hotter fire and perhaps timing. The first year also had accumulated multiple years of thatch which may have assisted fire intensity. Supplementary chemical control was effective, particularly when the fire created gaps between the grasses, allowing for better targeted chemical control.

Future directions: So far the results have shown that an August fire followed by the targeted chemical control of exotic grasses has considerable positive influence on the overall environmental integrity of this ecosystem. The annual burning allows the EEC to remain a grassland by killing off Coast Banksia and Coastal Acacia seedlings. It invigorates Kangaroo Grass growth and reduces the biomass of exotic perennial grasses at least in the short term. This again creates an opportunity in the aforementioned targeted chemical control. The herbaceous composition of the headland also remains intact and future analysis will determine whether burning has either a neutral or positive effect on growth. Kikuyu, Paspalum (Paspalum dilitatum) and annual exotic weeds continue to be the main problem. Increased post-burn selective herbicide application or hand weeding and planting of Kangaroo Grass tubestock may help to restore the grassland more rapidly than use of fire with limited weed control alone. Ongoing funding is being sought to continue the works over coming years and achieve further positive future outcomes.

Acknowledgements: The works were undertaken by Eurobodalla Shire Council with funding from the NSW Environmental Trust. Fire assistance from the NSW Rural Fire Service and cultural advice provided by Elders of the Walbunja people.

Contact: Tom Dexter; Environment and Sustainability Project Officer; Eurobodalla Shire Council (PO Box 99 Vulcan St Moruya 2537, Australia. Email: tom.dexter@eurocoast.nsw.gov.au).

Fig 5. Hemarthria uncinata was more evident after fire. (Duesburys Beach headland.)

Fig 5. Hemarthria uncinata was only evident after fire. (Duesburys Beach headland.)

Fig 5. More forbs among the grass after fire at Duesburys Point – e.g. Sellaria radicans

Fig 6. The forb Sellaria radicans persisted  among the grass after fire.

 

Reconstructing Western Sydney Grassy Woodland Understorey at Hoxton Park, Sydney, NSW

By Christopher Brogan

Purpose of the project. Endeavour Energy sought to restore a small highly disturbed Cumberland Plain Woodland bushland remnant at the West Liverpool Zone Substation at Hoxton Park, to offset 12 native trees removed to facilitate construction works at their electricity substation.

Condition of the site. The Cumberland Plain Woodland remnant was very small (approx.0 3.ha) and contained relatively healthy examples of four native trees (Grey Ironbark Eucalyptus crebra, Grey Box E. moluccana , Forest Red Gum E. tereticornis and some Paperbark Melaleuca decora). However, the native shrub and ground layer was generally absent and the soil surface was highly compacted with a low organic matter content. This was due to historic clearing for agriculture, recent clearing for the installation of electrical infrastructure and the fact that a layer of coarse fill material and asphalt had been deposited over the topsoil in some areas (probably for car parking).

Goals. As we found fragments of 3 grasses and 6 forbs remaining on site, our goals were to protect and enhance all remaining plants by ecologically sensitive weed control and planting of missing species from the Cumberland Plain Woodland community.

We had 24 months to achieve the revegetation, with performance criteria being: a survival rate of >80%; a reduction in the percentage cover weed to < 5%; and, an increase in percentage cover of the herbaceous layer to 67% – 100%.

Fig 1. Weed control included cut stump poisoning of woody weeds and high volume herbicide spraying of invasive perennial grasses.

Fig 1. Weed control included cut stump poisoning of woody weeds and high volume herbicide spraying of invasive perennial grasses. (Photo C Brogan)

Around 260 cubic metres of recycled wood waste was used to mulch to a depth of 100mm over 2,600 square metres.

Around 260 cubic metres of recycled wood waste was used to mulch to a depth of 100mm over 2,600 square metres.(Photo C.Brogan)

What we did. We identified two zones on site: Zone 1 – with capacity for assisted regeneration; and Zone 2 – without capacity for assisted regeneration. Zone 1 was treated using standard bush regeneration techniques – i.e. removal of weed to facilitate natural regeneration. Zone 2 treatments included: weed control, mulching with recycled wood waste (2,600m2 x 100mm deep); planting with 9,100 native tubestock (3-4 plants /1m2) raised from Western Sydney seed; and watering throughout the first month.

After some assisted natural regeneration and planting 9,100 native tubestock (raised from Western Sydney seed) a strong cover of native understorey was reinstated.

After some assisted natural regeneration and planting 9,100 native tubestock (raised from Western Sydney seed) a strong cover of native understorey was reinstated. (Photo. C Brogan)

The Presentation Title

Same part of the site taken before and after treatment.

Same part of the site taken before and after treatment. (C Brogan)

What advice can we offer?

  • Always check your project site to identify any fragments of native species which may be present and protect them during weed control works, particularly when spraying herbicide.
  • Use good quality tubestock of the appropriate provenance and budget for a seed collection program if the project timetable allows.
  • Never underestimate the need to water tubestock during hot months and allocate sufficient resources to watering.

Contact: Christopher Brogan, Earth Repair and Restoration Pty Ltd, PO Box 232 Panania NSW 2213. Tel: +61 (0)2 9774 3200 Email: chris@earthrepair.com.au; Web: www.earthrepair.com.au

Acknowledgement. This is summarised from a talk first presented to the symposium ‘Rebuilding Ecosystems: What are the Principles?’ Teachers’ Federation Conference Centre, November 13th, 2014, Australian Association of Bush Regenerators (AABR).

 

 

Yarrangobilly Native Seed and Straw Farm

Elizabeth MacPhee and Gabriel Wilks

Yarrangobilly Caves is a tourist destination within Kosciusko National Park (KNP), New South Wales. The Yarrangobilly Caves Wastewater Treatment Plant (WTP) has been established to treat greywater produced at the tourist centre, to stop nitrogen moving into the limestone karst system of the caves.

To optimise benefits from the WTP, the Rehabilitation team undertook the planting of locally native grass species in the discharge area, with a view to producing seed and weed-free mulch for use in the KNP Former Snowy Sites restoration program.

Effluent is initially treated using a bacterial blivet and then undergoes an ultra-violet treatment process so that it is within a “greywater” classification. It is then stored in a 200,000 litre tank and released under pressure to a discharge area. Prior to being discharged the effluent is diluted with fresh water to an average ratio of 7:3 (effluent:fresh water) in order to reduce the total nitrogen in the irrigated water to around 10 mg/L, which has been used as a threshold figure for nutrient loading. Once at the right concentration, the effluent is discharged in a large flat sedimentary rock area of about 1 ha in size.  The irrigation area in which the plant species are grown is approximately 0.5 ha.

Vegetation treatments. From 2006 to 2010, some 20,000 plants of a number of species of the grass genus Poa were planted in the discharge area of the WTP, at 50cm spacings (Fig 1).  The four main species were: Poa costiniana; P. fawcettiae, P. sieberiana and P. ensiformis; all native to KNP. Over the last 6 years, more than 300 kilos of highly viable Poa spp. seed has been collected and used in restoration works across the Park. The thatch (seed heads and cut off straw) has also been harvested and used as mulch on some of the sites.

Other species needed for rehabilitation in KNP have also been planted in the site over the last two years. Bossiaea foliosa and Lomandra longifolia have been grown for seed production and a variety of difficult to germinate shrubs have been grown to provide cutting material for propagation.

Soil sampling and soil treatments. Sampling was conducted prior to and after plant harvest to gauge the soil’s physical and nutrient status.  The samples (10cm cores of topsoil and subsoil) were sent to the Environmental and Analytical Laboratories at Charles Sturt University for analysis of Total Phosphorus and Total Nitrogen. (ammonia and nitrates as Nitrogen and phosphorus as Phosphorus (Bray)).

As early soil tests showed that pH reduced, Lime was applied to the discharge area in 2010 at 1 – 1.5 tonnes to to raise topsoil pH approximately 1 unit.

Results.

Seed and mulch production: Within the first 18 month period, nearly 100 kilos of seed was collected. To date over 300 kilos of highly viable Poa spp. seed has been collected and used in rehabilitation across the park, with the 2011/2012 harvest producing approximately 58 kilograms of seed. In the 2012-12 harvest, an estimated 288 kilograms of thatch was removed for use as mulch in restoration areas in the Park.

Soil fertility. More nitrogen and phosphorus was discharged during the 2011/2012 season than could be removed by plants season, with the native species having naturally low nutrient removal rates. Annual soil monitoring and peizometer monitoring of the ground water is keeping track of the use and movement of nitrogen in this landscape and to monitor any changes in soil chemistry.

 Suggestions for improvements:

  • Review irrigation scheduling to ensure the bulk of irrigation is occurring from November to March when nutrient uptake will be at its highest (rather than in the cooler months).
  • De-thatch the grass species at the start of spring to encourage fresh re-growth and therefore improve nutrient uptake over the spring and summer months
  • Test effluent on a regular basis to assess salt load;
  • Further treat effluent to reduce the nitrogen, phosphorous and sodium load;
  • Monitor and adjust pH as required; and
  • Reseed bare patches to maximise nutrient uptake by plants.

 In 2012 a progressive replacement planting program commenced, where sections of the oldest plants were poisoned and replaced with young plants. This continual renewal replanting will ensure the plantation remains actively growing, taking up maximum levels of nutrient and producing high quality seed and mulch.

Acknowledgements.  Funding for this project came from The Former Snowy Sites Rehabilitation project with soil and plant nutrient data provided by D.M McMahon (2008, 2012): Environmental Monitoring Use of Effluent for Irrigation, Yarrangobilly Caves, NSW. Environmental Consultants (agronomy) Wagga, Wagga.

Yarrangobilly grasses ready for harvesting

Yarrangobilly grasses ready for harvesting

The plantings are mainly four local species of Poa

The plantings are mainly four local species of Poa