Restoring upland swamps of Scott Creek in the
Southern Mount Lofty Ranges of South Australia
Project profile for the Society for Ecological Restoration International and Global Restoration Network
Friends of Scott Creek Conservation Park , March 2009
1. SUMMARY AND INTRODUCTION
This profile summarises a large remnant-scale ecological restoration project in the Scott Creek subcatchment of the southern Mount Lofty Ranges, South Australia. The project incorporates multiple sites containing threatened flora and ecological communities and covers a wetland aggregate of state, and potentially, national significance. Restoration sites are located along the headwaters of the first-order streams of Scott Creek, a major tributary of the Onkaparinga River catchment. The project is improving the condition of critical habitats for 32 threatened or regionally declining plant species and 2 state threatened ecosystems.
The project area contains headwater and riparian wetlands that have been substantially changed through human use and conversion for water exploitation, livestock grazing, and agriculture. Past removal of native vegetation, substrate disturbance, and watercourse degradation have resulted in altered vegetation communities and dense environmental weed invasion. Prior to restoration work focal sites contained degraded communities with only very simplified assemblages of indigenous species.
Weed species formed over 80% of vegetation cover, resulting in displacement of native plant species, depletion of native seed banks and impairment of regeneration processes. Without active intervention there was no likelihood of autogenic ecosystem recovery.
Restoration of the tributaries and headwater swamps of Scott Creek has been a priority of the Friends of Scott Creek for over fourteen years. Our aim is to restore an indigenous composition for degraded headwater and swamp vegetation. We are restoring these wetlands by regenerating native vegetation through environmental weed control, assisted regeneration, selective tube-stock plantings and by reducing incision of stream channels. We believe the potential for restoration through assisted natural regeneration is very good if a strategically staged approach is adopted over multiple years to enable active adaptive management.
1.1 Conservation Imperative
Around 75% of swamp habitats in the southern Mount Lofty Ranges have been extirpated (Littely 1998), and just 2% of remaining swamps are still regarded as being pristine (Harding 2005). Remaining swamps are degrading through livestock grazing, chronic weed invasion, erosion, altered water regimes, and insensitive land management. Of the regions riparian vegetation just 1% is considered to remain in ‘good health’ (SA Water 2000). The associated loss of indigenous wetland species continues as a largely unheralded environmental disaster and a contributing reason for the regions status as a National Biodiversity “Hotspot”. While the plight of the regions bird fauna has been well publicised the decline of indigenous wetland flora has received little attention aside from the efforts of a few motivated community conservation groups.
2. GEOGRAPHIC LOCATION
The project is located within the Scott Creek Conservation Park and on adjacent private land, situated approximately 30 kilometres south east of Adelaide in the southern Mount Lofty Ranges. The park is 800 hectares in size and dissected by many steep gullies with most creeklines rising within the park. The project area occurs within a larger native vegetation block that has been identified as an important conservation area (Mt Bold-Scott Creek), being the second largest bush complex in the Mount Lofty Ranges, a region identified as a national biodiversity hot-spot, containing just 13% remnant vegetation of which only around 5% is considered intact (Smith et al. 2003).
3. STAKEHOLDERS & BUDGET
The project is a partnership between Friends of Scott Creek Conservation Park, the Threatened Plant Action Group (TPAG), private landholders and the Department for Environment and Heritage. Grant funding has been received from DEH, SA Water, Urban Forests and Biodiversity Program, and the Natural Heritage Trust. Until 2006 our annual budget was around $2000 per annum. The Friends Group and TPAG successfully applied for a $25K Grant from NHT in 2007 which will be spent on contract onground management work over eighteen months.
4. ECOSYSTEM & IMPACTS
4.1 Previous ecosystems
The few remaining examples in the district suggest that typical headwater swamp ecosystems consisted of a varying mosaic of plant associations including tea-tree and wattle shrublands over ferns, sedges, rushes and herbs. Swamp wattle (Acacia provincialis), Silky tea-tree (Leptospermum lanigerum), Prickly tea-tree (L. continentale), Red-fruit cutting-grass (Gahnia sieberiana), Tall sedge (Carex appressa), Square twigrush (Baumea tetragona), Soft water-fern (Blechnum minus), Hop goodenia (Goodenia ovata), and Mount Lofty ground-berry (Acrotriche fasciculiflora) are the dominant species. These creek swamp communities intergrade with riparian Manna gum (Eucalyptus viminalis ssp. viminalis) and dry sclerophyll Messmate stringybark (Eucalyptus obliqua) woodlands. Threatened fauna such as the Southern Brown Bandicoot (Isoodon obesulus), Bassian Thrush (Zoothera lunulata), Beautiful Firetail (Stagonopleura bella), Lewin’s Rail (Rallus pectoralis) have been recorded for some sites.
Past removal of native vegetation, substrate disturbance, and watercourse degradation have resulted in altered vegetation communities and dense environmental weed invasion. Past ecosystem impacts include clearance of native vegetation, livestock grazing, soil cultivation, fertilisation and compaction, manipulation of surface water flow and creek channels. Both non-indigenous plant and animal species (Blackberry, Willow, Broom, Erica, fruit trees, cats etc.) were introduced in the past. Prior to restoration work these degraded communities contained only simplified assemblages of indigenous species with weed species forming over 80% of the sites vegetation cover, resulting in displacement of native plant
species, reduction of native seed banks and impairment of regeneration processes.
4.3 Causes and duration
Prior to 1970 most of the creeklines and swamps in the project area formed part of small privately owned bush blocks which had been partially cleared or modified for subsistence horticulture from the early to mid 1900’s. Following park gazettal the area was abandoned in the early 1970’s. Unchecked invasion by woody weeds followed and dense Blackberry (Rubus fruticosus aggregate) stands developed along creek lines in the project area, excluding and suppressing most indigenous species. Prior to commencing restoration work (c. 1997) almost all of these areas were severely degraded by dense Blackberry, Willow, Broom and Erica infestations. Native plant regeneration was further impaired by introduced and native herbivores which were often in high numbers close to the creeks.
5. RESTORATION GOALS AND PLANNING
The broad aim of the project is to return targeted ecosystems (insofar as possible) to pre-1836 composition and species richness and to improve vegetation structure and condition from virtual weed monocultures (i.e. Blackberry thickets) to their presumed structurally diverse and species rich state.
Our goals for ecosystem restoration are to:
increase native plant abundance (cover, density);
increase native species diversity;
stabilise and/or augment threatened plant populations;
reduce weed biomass over time as wetlands recover;
increase the area of available habitat for indigenous species.
demonstrate a practical restoration model for broader application
6. PROJECT IMPLEMENTATION
The general technical strategy for restoring degraded native vegetation communities is to:
define priority areas to be restored;
assess sites and determine the presence of indigenous species;
undertake brush-cutting to establish access into Blackberry thickets;
cut and swab shrub weed species, stem inject tree weed species;
allow blackberry to regrow and spray regrowth;
assess and protect regenerating indigenous plant species;
propagate non-regenerating indigenous species and establish in bare areas to assist recovery of indigenous vegetation;
frequently follow-up weed regrowth by hand pulling and by spot spraying;
expand intensively managed areas once recovered and where implementation resources permit; and
patrol and maintain all previously worked areas through ongoing weed control.
Implementation standards have been achieved by careful consideration of the following ecological and management factors.
The adopted weed control methods have reduced herbicide use and off-target damage and maximised selectivity. Approaching work this way has allowed a closer examination of regenerating areas. We have tried keeping disturbance to native vegetation, soils, water, and substrates to a minimum. Careful hand weeding has reduced disturbance and prevented opening up too much ground too quickly, an important factor as weed species often establish much faster on disturbed ground than most natives.
Seasonality & timing
Seasonal factors and plant growth have been considered in scheduling management tasks. Blackberry spraying has been done in optimum conditions and not just by a monthly calendar. As conditions vary each year weeds have been observed and treated during active growth periods, when under the least stress. Cut and swabbing or stem injection is more flexible but has been avoided when weeds are heat/water stressed or during dormant phases.
The regenerative capacity of native vegetation and residual seed banks has been utilised instead of mass planting to guide natural regeneration. We have been surprised by the longevity of native seed banks in some areas where Blackberry has long dominated. We have found it much more important to wait and observe what regenerates before revegetating with extrinsic material. Where after time it is obvious that few natives are regenerating or weeds appear the only germinating plants, augmenting with locally sourced tube-stock is carried out. With species like Tea-trees seed can be hand broadcast to effectively increase regeneration. Herbivory by rabbits, deer and kangaroos has also taken a heavy toll in some regenerating areas.
Gradual, staged implementation
All work implemented over the past twelve years has been in gradual stages with the rate of natural regeneration utilised to guide the intensity of required management intervention and expansion of work into new areas. Invaded areas have opened up slowly as rapid removal of established habitat will impact on those species which have adapted to it. This is especially the case with several bird species. We are very conscious of this and only work on 50-100 meters in one area at any one time. We only continue further when that section has regenerated to a state where it is providing comparable vegetation cover to the prior infestation. Harnessing the regenerative capacity of managed sites has helped build their ecological resilience and aided their recovery.
Translocations (augmentation plantings) are being considered for small threatened plant populations. Several small swamp herbs and sedges have been slashed around to maintain required successional habitats and patch diversity. A nomination has been prepared for the Directory of Wetlands of National Importance as part of the project (Jury et al. 2006). Project leaders are experienced practitioners with advanced botanical and on-ground management skills. Project volunteers have been well trained in restoration and management techniques. Careful pre-work surveys and detailed botanical reconnaissance has been undertaken through regular visits to all sites. Unknown species have been retained until positive identification by expert field botanists. Only experienced, specialist contactors with stipulated work briefs have been utilised. Ongoing monitoring and evaluation has been undertaken for all implemented work.
7. PROGRESS TO DATE
Restoration work has been implemented for approximately 25 hectares of wetland and 100 hectares of adjoining dry woodlands, open forests and heaths. Removal of Blackberry thickets and other dense invasion by environmental weeds (Willow, Erica, Broom, Boneseed) has stimulated prolific regeneration of structural wetland species. Regenerating indigenous shrubs, ferns, sedges, rushes and herbs are returning to presumed pre-contact composition and providing suppression of weed regrowth. All targeted areas are now regaining floristic diversity with the regeneration of wetland flora, including rare species. Attributes and restoration progress are indicated for some sites below.
7.1 Specific project sites
A permanent spring-fed creek containing Manna gum over Silky tea-tree and swamp wattle shrubland, sedges, ferns and rushes. Almanda Creek contains permanent pools inaccessible to non-native trout and is therefore an important refuge for a local population of Mountain Galaxias (Galaxias olidus). The state threatened Sickle greenhood (Pterostylis falcata) and Blue-star (Pratia pedunculata) creeper inhabit creek banks and Lewin’s Rail (SA Vulnerable) was first sighted here in 2006 (2 adults & 1 young). Blackberry has been retained along an adjoining roadside to limit recreational impacts.
Mackereth Creek/Fox Bog
A perched fern bog between two waterfalls above small gorges and a broader creek swamp. Staged removal of Blackberry cover has resulted in discovery of two new regional plant species records for the southern Mount Lofty Ranges, namely: Swamp mazus (Mazus pumilio) and Pratia puberula. The SA Endangered Mount Lofty Speedwell (Derwentia derwentiana) and rare water-fern (Blechnum aff. wattsii) have been discovered following Blackberry removal.
Bush Rat Creek
Blackberries previously covered all but the oldest tea-trees creating a dense, shading thicket unsuitable for indigenous species. The Mount Lofty Ranges Speedwell was disappearing under blackberry however careful removal through cutting and swabbing around surviving individuals has resulted in vigorous shoot production, seeding and the recruitment of several new seedlings. The SA Threatened Small bent-grass (Deyeuxia minor) and rare Swamp raspwort (Haloragis brownii), not previously recorded in the park, also appeared following blackberry removal. Most of the Leptospermum lanigerum stands were senescing without recruitment and reasonably intact native vegetation occurred close to the creekline.
Long dormant seed of Golden spray (Viminaria juncea) germinated within months of blackberry removal. This species had previously died out in this creekline as well as Swamp raspwort (Haloragis brownii) which has also since recolonised along with a suite of shrubs, ferns, sedges and rare grasses. Only a few senescing Leptospermum lanigerum and Blechnum minus remained but the creekline now has stands along its whole length.
Picture 1: Upper Viminaria Creek 1 year after Willow and Blackberry removal, 1998
Picture 2: Upper Viminaria Creek following assisted regeneration, 2009
7.2 Interest in the project
Whilst there has been some interest from government agencies and other community groups, there is little evidence that our approach is catching on. Limiting the adoption of our restoration approach at a broader scale are:
Lack of required botanical recognition skills and experience working with ecological processes (such as succession);
Lack of awareness of weed invasion threats to biodiversity or at least preparedness to tackle the problem appropriately;
Lack of patience and persistence in gradually implementing restoration work;
Unwillingness to commit to the physical work required to restore degraded ecosystems.
The challenging and long-term temporal scale of restoration and lack of support to progress such work.
Human tendencies to merely intellectualise problems rather than shouldering direct personal responsibility in addressing them.
A preoccupation by government and academia with conservation science, policy and planning at the expense of on-ground implementation and tangible outcomes.
7.3 Monitoring and research links
Annual monitoring of vegetation structure and species composition is being undertaken to evaluate the effects of management. Photo-points and transects (point-line intercept & interval plots) have been established to monitor changes in vegetation structure and composition. Ongoing population counts are undertaken for threatened plant species. Updated site species lists have been compiled by expert field botanists on an ongoing basis. Permanent vegetation monitoring quadrats using NCSSA Bushland Condition Monitoring methodology are planned for 2009. Bird Banding has been undertaken near some sites.
7.4 Lessons learned
Our work has demonstrated that a high level of natural regeneration is still possible on wetland sites after assisted regeneration treatments, despite the sites having been so degraded that few native species were evident. Site restoration has been achieved mainly through staged implementation of selective weed removal. Three methods of Blackberry control have been adopted.
1. Buffer creation - cut and swabbing of Blackberry to create a managed ‘buffer’ zone around rare or threatened species or where indigenous species are well established, before using other methods to expand weeded areas.
2. Slashing in better sections - Thickets of dense Blackberry are slashed to just above ground level in winter, allowed to regenerate until summer then sprayed. This has proven effective for smaller areas and/or where higher native biomass or species richness is present, as regeneration of natives is easier to observe from the beginning. Spot spraying of Blackberry regrowth can then be carried out several times over the following summer.
3. Large dense infestations - Larger, mass infestations have been sprayed and left for a year. This method leaves dead canes as habitat for some time before they break down to enable control of regrowth. It can take longer for native species regeneration but end results are similar. Only 50-100 metres are done in this way at any one time.
No magic bullets or quick fixes have been found for restoring these ecosystems. The importance of regular follow-up spot spraying in the first few years (at least twice per season) is critical in reducing future weed control demands. After this time most germinating blackberry is from seed and easily hand pulled. Selective weed management techniques and strategic follow-up work have been crucial to longterm success. Regular botanical searches (before & after) are an essential part of ecosystem monitoring as seed banks contain both new native and exotic species which can be overlooked. Early identification of any new germinating species has been very important.
Picture 3: Upper Bushrat Creek following Blackberry slashing, June 2005
Picture 4: Upper Bushrat Creek following assisted regeneration, November 2006
Picture 5: Upper Bushrat Creek following assisted regeneration, March 2007
Picture 6: Upper Bushrat Creek following assisted regeneration, March 2009
8. FURTHER READING
Bates R (2005) Rare and localised plants in three sister fern-bogs of Scott Creek CP. Bandicoot Tails. 97 April-May 2005, Newsletter of the Friends of Scott Creek Conservation Park.
Harding CL (2005) Wetland Inventory for the Fleurieu Peninsula, South Australia. Department for Environment and Heritage, Adelaide.
Jury T & T Hands (2005) Restoring plant diversity in upland swamps of the Mount Lofty Ranges.
Australasian Plant Conservation. Vol 13, 3 December 2004 - February 2005.
Jury T, T Hands, R Bates & D Reid (2006) Nomination of Scott Creek Perched Swamps for the Directory of Important Wetlands in
Littlely, T. (1998). A Biological Survey of the Fleurieu Peninsula Swamps. Report prepared for the Nature Conservation Society of South Australia, Adelaide.
Smith K, A Prescott, C Carter & T Berkinshaw (2003) Native Vegetation Management: A needs analysis of regional service
delivery in South
Australia. Bushcare/Natural Heritage Trust. Enviornment
SA Water (2000) The State of Health of the Mount Lofty Ranges Catchments from a Water Quality Perspective. Environment Protection Agency. Adelaide, South Australia.
Weblink to Friends of Scott Creek Conservation Park: Regeneration.htm
9. CONTACT INFORMATION
For information about this project, contact:
Mr Tom Hands
President, Friends of Scott Creek Conservation Park
Phone: (08) 8388 2150
Compiled by Tom Hands and Tim Jury, March 2009 with input from Tein McDonald. Thanks to all who
have participated in or supported the project, particularly members of the Friends of Scott Creek
Conservation Park including John Butler, Robert Bates, Don Reid, Rick Williams, Peter Charles, Peter
Watton and Jenny Dawes.
Hands T & T Jury (2009) Restoring upland swamps of Scott Creek in the Southern Mount Lofty Ranges.
Project profile for the Society for Ecological Restoration International and Global Restoration Network.
Friends of Scott Creek Conservation Park and Threatened Plant Action Group. Adelaide, SA.
the park Amphibians Animal
history Bandicoot Tails
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