Key Words: reconstruction, assisted regeneration, planning, koalas, conservation
Introduction: The Stewartdale Nature Refuge is located in South Ripley, south east Queensland on private land owned by the Sporting Shooters Association of Australia (SSAA). The 969 ha block contains live shooting ranges, large open areas dominated by pasture grasses, a substantial lagoon frequented by many bird species and extensive natural areas. The area being restored is 211 ha of dry sclerophyll vegetation, containing a number of Regional Ecosystems (REs) being restored through large scale planting (reconstruction) and assisted regeneration approaches. Its conservation value is heightened by the fact that it connects to the Karawatha Flinders Corridor, the largest remaining stretch of open eucalypt forest in south-east Queensland.
Condition ranges from large degraded areas (i.e. pasture) to native vegetation that contains both regrowth and remnant dry sclerophyll. All areas were impacted by varying levels of weed infestation due to previous clearing and ongoing disturbance from cattle grazing. Natural disturbances such as regular fire and periodic floods have also contributed to disturbance at the site. More than 30 weed species impact the project area at varying levels and the species and impacts vary with the condition of the land. Open areas were dominated by pasture grass such as Setaria (Setaria sphacelata) and Rhodes grass (Chloris gayana) in addition to fast growing annuals, although infestations of Leucaena (Leucaena leucocephala), Prickly Pear (Opuntia stricta) and large clumping Bamboo (Bambusa sp.) also required significant control efforts. In more forested areas (and underneath isolated remnant trees) weed species included Lantana (Lantana camara), Creeping Lantana (Lantana montevidensis), Corky Passionfruit (Passiflora suberosa), Easter Cassia (Senna pendula var. glabrata), Siratro (Macroptilium atropurpureum) and exotic grasses, annuals and groundcovers.
The aim of the project is to restore, native plant communities present within the Stewartdale project site to support local koala populations. Our goals are to:
- Repair native vegetation including the structure, integrity and diversity to support koala populations
- Strengthen the resilience and regenerative capacity of native vegetation
- Restore and expand native regrowth vegetation by controlling weeds
- Maintain the project site so weeds do not negatively impact the development and recovery of native vegetation
- Protect drainage lines, gullies and slopes from erosion
- Protect and enhance the water quality of Bundamba Lagoon
- Construct fauna friendly fencing across the site with the aim of protecting planted trees from herbivory
- Reduce the risk of fire moving through the site and impacting restoration works by conducting strategic slashing activities to reduce fuel loads.
Planning. A restoration plan was developed after detailed site assessments and negotiations with the landholder, land manager and state government were finalised integrating Nature Refuge conditions and current land use and future management requirements. The site was divided into zones and sub-zones to assist directing works including applying a range of restoration approaches – i.e. assisted regeneration and reconstruction (‘revegetation’) and several planting models and species mosaics to different parts of the site. Detailed maps were produced for each zone and included information such as the location of all tracks, fences, assisted regeneration zones, wildlife corridors, planting areas according to each RE and numbers of species and plants to be installed per zone. The plan also included detailed information on restoration approaches; weed control at all stages of the project; seed collection and propagation; site preparation including the specifications and location of all fencing, tracks, rip lines and areas of concern (i.e. identified hazards across the site); how to carry out all works in each zone; site maintenance requirements for 5-7 years; and monitoring requirements.
Works to date. Site preparation commenced with the collection of seed from on and around the wider property and surrounds ensuring that all species to be planted were collected from a minimum of 10 widely spaced parent trees. Primary weed control started with the control of weeds in the 65 ha of assisted regeneration zones and the control of other woody weeds across reconstruction areas in preparation for slashing and other activities. More than 18 km of fauna friendly fencing (i.e. no barbed wire) was installed to protect planted stock from browsing by large herds of macropods and cows. Two large corridors were retained for fauna to reach Bundamba lagoon from different parts of the regional corridor as it is an important resource for many local and migratory fauna. Slashing across open areas was commenced and followed by the installation of rip lines to alleviate soil compaction and assist efficient planting activities. Weeds and pasture grasses were then sprayed out along all rip lines. 114 000 koala food and shelter trees were planted according to the RE for each section and according to the local conditions (i.e. whether it was low lying, on a ridge or near infrastructure). Some additional frost resistant and local Acacia species were also added to particularly frost prone areas to assist the development of a canopy and the protection of developing vegetation.
The 114 000 tubestock were installed over a 7 week period with the last stems being planted in April 2015. All trees were fertilised and watered at the time of planting and where possible, slashed grass spread across the rip lines to assist retaining moisture and slowing weed regrowth. (Follow-up watering was applied to all planted stock between September and October 2015) Nearly 2000 (1 m high) tree mesh guards were installed to protect planted stock in fauna corridors.
Results to date. As of March 2016, weeds have been significantly reduced across the 65 ha of assisted regeneration areas. Unfortunately a wildfire fire went through approx. a third of the project area after primary and follow up weed control works had been completed. Fortunately the event was prior to planting though the fire did reduce the number of trees regenerating in assisted regeneration patches as many were too young to withstand the fire. New germinations are however occurring and the level of native grasses, groundcovers and other native species have increased due to ongoing weed control efforts.
Despite heavy frosts in winter 2015, a flood event in May 2015 (150 mm of rain fell in 1.5 hours) and now an extended dry period, the planting is developing well with the average height of trees at over a metre tall and mortality under 5%. Weed control is continuing across the project site with efforts currently concentrating on the control of many annual weeds such as Cobbler’s Peg (Bidens pilosa), Balloon Cotton (Gomphocarpus physocarpus) and Stinking Roger (Tagetes minuta) and many exotic grasses such as Setaria (Setaria sphacelata) and Rhodes grass (Chloris gayana) to reduce competition to planted stock. Assisted regeneration areas are being joined up to planting zones wherever possible to further assist the development of the site.
It should also be noted that Birds Australia have recorded 69 bird species on site.
Ongoing works: Regular maintenance continues on the site with the control of weeds particularly along rip lines where weed germination and growth is rapid. Slashing is also regularly done between the rip lines and along tracks and fence lines to assist access around the site and the management of fuel loads and therefore wildfire across the site. It is expected that the time it takes to complete each maintenance rotation will begin to reduce as plants become more established and start to develop a canopy.
Weed control will also continue in all assisted regeneration zones and is also expected to reduce with the development of native vegetation structure and diversity together with the reduction of the weed seed bank. Ongoing slashing, fence maintenance and monitoring will continue for another 3-5 years though the exact time period will be determined by the State government.
Monitoring including soil moisture readings, transects to assist determining survival rates across the site and photographic monitoring is regular and further supports 6 monthly reporting requirements.
Stakeholders and funding bodies: Department of Environment, Heritage and Protection, Queensland State Government; Sporting Shooters Association of Australia (SSAA). Photos: Ecosure.
Contact Information: Jen Ford (Principal Restoration Ecologist, Ecosure TEl: +61 (0)7 3606 1038.