Indicator: Ecological Communities

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Summary

Ecological communities in the ACT were affected by the January 2003 bushfires more than any other event during the 2000–03 reporting period.

Areas burnt by fires included sensitive higher altitude communities in Namadgi National Park, riparian communities in the Murrumbidgee River Corridor, and rural lands to the west and south of Canberra that include areas of lowland woodland. The impacts of the fires on ecological communities need to be monitored both short and long-term to better understand the regeneration processes and guide ongoing management of these communities both within and outside the reserve system.

Following those fires, a new potential threat to ecological communities in the ACT is arising in the form of extensive fire fuel hazard reduction by emergency services agencies charged with protection of life and property. Weed regeneration is also expected to exert additional pressures on biodiversity, particularly within lowland ecological communities.

In response to a recommendation by the Commissioner for the Environment in 2000, the ACT has worked with the local NSW National Parks and Wildlife Service to develop a consistent classification of ecological communities. Native vegetation of the ACT has now been classified into 28 ecological communities.

A conservation strategy for lowland woodland was prepared in 2002–03. It combines and integrates action plans for the Yellow Box–Red Gum Grassy Woodland community, plus eight threatened woodland species. In a more holistic approach to the recovery of both the endangered community and the threatened species, it includes other woodlands and secondary grasslands. The draft strategy must be finalised and its priority tasks resourced and implemented.

As a result of more detailed knowledge and public pressure, 1065 hectares of high quality Yellow Box–Red Gum Grassy Woodland and other woodlands in East O’Malley, Jerrabomberrra Valley and Gungahlin have been proposed for conservation.

Similar strategies for Natural Temperate Grassland (and component species) and aquatic species (and the riparian zone) are to be prepared in 2003–04.

What the results tell us about the ACT

The native vegetation within the South Eastern Highlands and Australian Alps biogeographic regions in the ACT have been classified into 28 ecological communities (see Table 1). These communities were identified after the NSW National Parks and Wildlife Service, Environment ACT and specialist consultants undertook analysis and review of NSW Southern Region Comprehensive Regional Assessment data (Fallding 2002), in response to Recommendation 5 in the 2000 State of the Environment report. This classification should allow better assessment and reporting on the condition and extent of the vegetation of the ACT. However, for planning and management purposes, particularly of endangered ecological communities, Environment ACT will continue to use more detailed data. There has been no modelling of the change of coverage in these 28 communities since European settlement, and it is not known whether such modelling will be done in the future.

The Planning Framework for Natural Ecosystems of the ACT and NSW Southern Tablelands (Fallding 2002) was completed during the reporting period, also from the NSW Southern Region Comprehensive Regional Assessment data. This classifies vegetation communities into broader groupings of native grassland, grassland–woodland mosaic, Box Gum woodland, dry forest, wet forest, riparian forest and heathland–shrubland–herbfield–rock.

Vegetation loss since 1750

Modelling of the pre-European extent of some of the broader ecological communities of the Planning Framework for Natural Ecosystems of the ACT and NSW Southern Tablelands has shown a significant historical reduction in their extent. For example:

  • Natural Temperate Grassland (C1–C3 in Table 1) has been reduced from its estimated pre-1750 extent of 11 per cent of the region to one per cent in 2000
  • Box Gum woodland has been reduced from an estimated pre-1750 extent of 23 per cent to nine per cent in 2000 (Fallding 2002).

ACT ecosystems continue to be threatened

Key threats to ACT ecological communities include clearing and fragmentation of vegetation, loss of natural integrity, fire, weed invasion, pest animals and grazing. These were identified in Fallding (2002, p. 34), which described a range of threats to natural ecosystems on a scale from continental (climate change) to a particular site (for example, inappropriate mowing or grazing regimes).

Changed fire regimes a concern

Long periods without fire, or fire at too frequent intervals or at high intensity are detrimental to the survival of many species. Associated with drought conditions, two major bushfires in the ACT during the reporting period had the most significant impact on the condition of ecological communities. The December 2001 fire mainly affected pine plantations, but some parts of Canberra Nature Park (162 hectares at Red Hill, 84 hectares at Bruce Ridge and 17 hectares at Wanniassa Hills) were also burnt.

The much larger bushfires of January 2003 burnt 70 per cent of the ACT, including 90 per cent of Namadgi National Park, virtually all of Tidbinbilla Nature Reserve and the Murrumbidgee River Corridor, and rural areas to the west and south of Canberra that include areas of lowland woodland.

Table 1 identifies general locations of ecological communities. Fire severity varied from moderate to very high and will have short- to long-term impacts on affected ecological communities, in particular, high elevation wetlands. The only ecological communities not affected by fire were the dry and wet tussock grasslands (C1–C3, . A report by Carey et al. (2003) documents the initial impacts of the fires on natural ecosystems as surveyed in early February to late May 2003.

The damage to ecological communities also had significant implications for soil stability, stream water quality and riparian zone quality and also government resources. From January to June 2003, $200,000 was spent to help restore fire-damaged riparian zones and $100,000 to help repair the Murrumbidgee River Corridor.

Clearing and urbanisation still a threat

Clearing and fragmentation of vegetation for urban and associated infrastructure development remain the main threats to lowland communities. As the ACT population continues to grow, lifestyle and expectations demand bigger houses for fewer occupants. Administrative arrangements also keep ACT governments focused on urban development within the ACT border, at the cost of lowland ecological communities. Where development would affect lowland ecological communities, the definition of ‘significance’ used in the Tree Protection (Interim Scheme) Act 2001 is used to protect some of the trees which might otherwise be destroyed.

Sale of land as a primary revenue source for the ACT Government and growing land use pressures within the Territory’s borders are likely to result in continuing pressure on particular woodland areas, especially North Gungahlin. About 1100 hectares of Yellow Box–Red Gum Grassy Woodland (of the total 10,870 hectares) remains in urban land use categories under the Territory Plan. The remainder is in Public Land Nature Reserve (2345 hectares, or 3457 hectares when new reserves are added); planning and land use categories under the Territory Plan and National Capital Plan that preclude urban and intensive development (6410 hectares); and Broadacre, Rural and Plantation forestry land use (2940 hectares).

Loss of natural integrity occurs as adjacent land uses impinge on ecological communities. For example, effects at the urban edge include removal of bush rock and fallen timber, dumping of garden waste, planting out into reserves from adjacent backyards, predation and disturbance by cats and dogs, and spread of invasive pest plants (such as Chilean Needle Grass and St John’s Wort). Increased fire fuel reduction, following the experience of the bushfires, also has potential for adverse biodiversity impacts.

The fires of December 2001 and January 2003 burnt substantial areas of pine forest plantation, creating an opportunity to alleviate some of the urban development pressure on lowland woodland communities. However, those areas are being considered for additional development, rather than as alternatives to more clearing and fragmentation of lowland communities.

Clearing not connected with urban development occurred in 2001 when a broad swathe of higher-elevation vegetation was cleared without authorisation from under power lines on the Brindabella Range in Namadgi National Park. Environment ACT obtained an out-of-court settlement from the contractor for reparation and compensation.

The effect of weeds and pest animals

Weeds are a major threat to low elevation communities and those at higher elevations where there have been past or current disturbances such as grazing and construction of roads and fire trails. Regeneration of weed species in response to the January 2003 bushfires and drought are expected to exert further pressure on ACT ecological communities.

Pest animals prey on native species, compete for food and breeding habitat, change habitats and transmit disease micro-organisms. Fauna of low elevation woodland and grassland remnants are particularly vulnerable to the effects of domestic and stray animals (such as cats), introduced species (such as Common Myna birds), and in some instances, native species that thrive in highly modified landscapes (such as Noisy Miner birds).

Grazing a threat, but signs of recovery in some areas

The impact of grazing is particularly relevant to lowland woodland and temperate grassland communities. Grazing by sheep, cattle and horses affects woodland understorey, tree regeneration and the composition of grasslands and has had a major negative impact on habitat quality and natural integrity through a loss of grazing sensitive species. However, grazing may be strategically used as a tool to manage weeds and grass biomass and thereby assists in maintaining or enhancing community values. Some areas in the ACT, such as Mulligans Flat and Crace Nature Reserves, where grazing has been removed, or is being used only as part of a carefully targeted management program, show extensive recovery.

Advances in protection and conservation

Landuse history protects some communities

The unique landuse history of the ACT has resulted in a high level of protection of higher altitude communities (including setting aside the mountain catchments of the Brindabella Range for water supply purposes), and in less clearing of the lowland Yellow Box–Red Gum Grassy Woodland than in the surrounding NSW Southern Tablelands.

In general, protection of ecological communities is in the form of Public Land categories in the Territory Plan and planning policies and land use categories in the National Capital Plan. Of the 28 communities in Table 1, 19 higher altitude communities are partly or entirely within Namadgi National Park. A further three (riparian) communities are protected in the Murrumbidgee River Corridor.

Biodiversity now considered when planning

The reporting period has seen a positive change towards better biodiversity considerations at the planning stage by, for example, allowing adequate buffers and not permitting housing on the outer edge of perimeter roads. Biodiversity conservation at the planning stage of developments must be consolidated and retained.

Land management agreements implemented Protection and conservation management of significant vegetation (for example, areas of Yellow Box–Red Gum Grassy Woodland) on rural leases in the ACT is provided through Land Management Agreements prepared under the Land (Planning and Environment) Act 1991 .

Establishing land management agreements is linked to granting of long-term (20- and 99-year) rural leases. More than 70 such agreements were in place at the end of the reporting period. One of the objectives of land management agreements is to preserve the extent and character of any threatened ecological community or population of a threatened species. The role of MOUs There are memoranda of understanding between Environment ACT and Commonwealth agencies that occupy land in the ACT, for management of threatened species and ecological communities on those lands. Examples of such areas are the Majura Valley (Grassy Woodland and native grassland) managed by the Department of Defence, and Stirling Ridge (Grassy Woodland) managed by the National Capital Authority.

Nature Conservation Act

Leasehold land in the ACT (both urban and rural) is mainly in the lowland areas. Ecological communities may be represented on these lands as remnants varying from small clumps of trees or grassland patches to single ‘paddock trees’ or isolated urban trees. The Nature Conservation Act 1980 provides for protection of native plants and ‘native timber’ on unleased land in the built-up area, and on leased and unleased land outside the built-up area, but also allows timber on rural leases to be felled for farm purposes or where it is potentially hazardous.

Tree Protection (Interim Scheme) Act

In March 2001, following community concern about the loss of trees in urban Canberra, the ACT Legislative Assembly passed the Tree Protection (Interim Scheme) Act 2001 to provide interim protection until a suitable form of tree protection was determined. This legislation applies to leased land in the urban area. Since the January 2003 bushfires, community concern about the presence of large trees has increased and pressure for their removal exerted.

Protection for endangered lowland communities

Both Natural Temperate Grassland and Yellow Box-Red Gum Grassy Woodland were declared endangered under the Nature Conservation Act 1980 . Both are still two of the most cleared ecological communities in south-east Australia.

Natural Temperate Grassland

Natural temperate grassland, declared endangered in the ACT in 1996 and nationally on 16 July 2000, is a low-elevation ecological community dominated by native perennial grasses with a diversity of native herbaceous plants. There are 68 sites at 39 locations in the ACT covering 1450 hectares (ACT Government 1997). There were no significant losses or modification to remaining sites, or establishment of new protected areas in 2000–03. Yarramundi Reach (National Land) was burnt in December 2001, but no areas were burnt in the January 2003 bushfires. Pressure on Natural Temperate Grassland is primarily from ongoing development of Canberra (loss and fragmentation, and degradation of remnants from weed invasion) particularly in the Jerrabomberra and Majura Valleys.

The ACT Government’s response to the pressure on the Natural Temperate Grassland has primarily been through the ACT's Action Plan 1. The Plan aims to avoid fragmentation and degradation, and promotes conservation on National Land and in the region, through the following activities:

  • education – publication of grassland flora field guide (Eddy et al. 1998), and a grassy ecosystem management kit is being prepared (Sharp et al. in prep.)
  • establishment of reserves – Gungahlin Grassland Reserves (Crace Hill, Gungaderra and Mulanggari) and Dunlop Grassland Reserve; these cover 206 hectares (14 per cent of remaining 1450 hectares)
  • monitoring – fifteen sites have been monitored annually since 1993, focused on changes due to differing types of management
  • onground management – weed control has been a major task with a focus on particular sites and problem weed species (for example, Chilean Needle Grass, African Love Grass). Conservation grazing is being undertaken on grassland reserves and the results monitored. Management plans have been formulated for grassland areas and regular liaison is undertaken with land managers.

The remaining Natural Temperate Grassland in the ACT is well-documented, recognised in planning studies, and some important areas have been secured in, or identified for, nature reserves. Potential degradation of sites, particularly from invasive weeds and effects from adjacent residential development are ongoing concerns. Environment ACT will, in 2003–04, prepare an integrated conservation strategy incorporating grassland and component species, including those declared threatened.

Yellow Box - Red Gum Grassy Woodland

Yellow Box–Red Gum Grassy Woodland, declared endangered in the ACT in 1997, is a low elevation open woodland community in which either or both Yellow Box (Eucalyptus melliodora) and Blakely’s Red Gum (E. blakelyi) are usually present and dominant or co-dominant. There is a species-rich understorey of native tussock grasses, herbs and scattered shrubs. The condition and protection of the community in the ACT is generally good, compared with remnants in surrounding NSW.

Knowledge of the condition of ACT lowland woodland improved during the reporting period, with surveys in 2001–02 forming the basis for the Draft ACT Lowland Woodland Conservation Strategy (2003). About 10,870 hectares of Yellow Box–Red Gum Grassy Woodland that meet the definition of ‘endangered ecological community’ remain – approximately one-third of the estimated pre-European extent of 32,000 hectares in the ACT (Landsberg 2000). Some 2345 hectares of the remaining endangered ecological community were in nature reserves at the time of assessment. Many areas remain on rural leases.

At the regional level, only 25,200 hectares (8.5%) of Yellow Box–Red Gum Grassy Woodland remain of the estimated pre-European extent of 295,000 hectares. It is therefore no longer possible for the ACT and NSW, either individually or combined, to achieve the generally used criterion of 15 per cent reservation (NLWRA 2002).

Compared with New South Wales, where threats to woodland remnants are mainly due to their location on rural land and rural subdivisions, in the ACT pressures on Yellow Box–Red Gum Grassy Woodland are primarily from Canberra’s ongoing development (clearing of woodland remnants, fragmentation of woodland, degradation of remnants, loss of structural integrity through understorey clearing). There is loss of paddock trees, and large trees in the urban area (from old age and infill development and for safety reasons). There are also significant long-term urban edge threats, as detailed above.

Recognition of the values of lowland woodland in recent years has reduced losses due to urban development.

At O’Malley, recent government decisions saw 62 hectares of Yellow Box–Red Gum Grassy Woodland removed from proposed residential development for addition to the Mugga Mugga Nature Reserve (upon completion of a Territory Plan variation). The adjacent 27 hectares of woodland that were also part of the proposed residential development sold for $32 million.

In May 2003, the ACT Government announced that two areas of Yellow Box–Red Gum Grassy Woodland identified in the Draft ACT Lowland Woodland Conservation Strategy are to be added to ACT nature reserves (750 hectares at Gooroo, East Gungahlin, and 300 hectares at Callum Brae, Jerrabomberra Valley).

ACT Lowland Woodland Conservation Strategy

The Draft ACT Lowland Woodland Conservation Strategy (ACT Government 2003) is indicative of the strong ongoing community interest in ACT woodlands.

The draft strategy supersedes nine separate Action Plans previously published for the Yellow Box–Red Gum Grassy Woodland, six threatened bird species and two plant species associated with lowland woodland. In response to community concerns, 6000 hectares of lowland woodlands that do not meet the definition of the Yellow Box–Red Gum ecological community are also included, along with areas identified as secondary grasslands.

While the draft strategy identifies priority conservation tasks, it still leaves some fragments of differing conservation value at risk. After the priority tasks were completed, there would remain up to 660 hectares of endangered Yellow Box–Red Gum Grassy Woodland fragments, 530 hectares of other woodland fragments and 600 hectares of paddock trees with little or no understorey, described in the draft strategy as ‘severely modified’ lowland woodland.

Even so, the draft strategy provides an integrated basis for future planning and management. It identifies off-reserve conservation as a particular focus for government and non-government activity. The majority of rural leases have land management agreements requiring conservation of woodlands and component species. Monitoring sites have been established in lowland woodland to measure changes in condition.

The draft strategy specifies actions for ‘best practice management’ guidelines, a review of management of government horse-paddocks, and an adaptive management approach to link research, monitoring and management. These types of activity will be an expanding area of interest.

Of particular note is the intention to participate in the regional Conservation Management Network (CMN) for Grassy Woodlands already operating in NSW. The CMN is a network of remnants of an ecological community, their owners and managers as well as other people with an interest in that ecological community. A CMN can help land managers access technical and funding assistance, develop management plans, participate in knowledge sharing, and establish voluntary agreements.

Data sources and references

Until this State of the Environment report, maps of ACT vegetation and vegetation communities in ACT State of the Environment reports have used data from the NSW National Parks and Wildlife Service. For the State of the Environment 2000 report, ecosystem types derived from the Comprehensive Regional Assessment study for the NSW Regional Forests Assessment (1997–2000) (Thomas et al. 2000) were used and were intended to act as broad surrogates for ecosystems.

Forest ecosystem classification for the NSW Southern Region Comprehensive Regional Assessment study was undertaken. The main objective was to prepare maps of the pre-1750 and 2000 forest ecosystems to assess the adequacy of their conservation on both public and private land. Approximately 200 forest ecosystems were identified, described and mapped (Thomas et al. 2000). A more detailed description of the process is in State of the Environment 2000.

Members of the team that revised the State of the Environment 2000 classification and prepared the classification of ecological communities reported in this indicator are Sarah Sharp, Environment ACT (Wildlife Research and Monitoring); Roger Good, NSW National Parks and Wildlife Service; Rainer Rehwinkel, NSW National Parks and Wildlife Service; Nic Gellie, Environmental consultant.

The work has been assisted and reviewed by a Scientific Reference Group.

References

ACT Government 2003, Woodlands for Wildlife: Draft ACT Lowland Woodland Conservation Strategy , Action Plan No.27, Environment ACT, Canberra.

ACT Government 2000, ACT State of Environment Report 2000: Conserving Biodiversity , ACT Office of the Commissioner for the Environment, Canberra.

Australian Heritage Commission 2002, Natural Heritage Charter , 2nd Edit, Australian Heritage Commission/Australian Council for the International Union for the Conservation of Nature, Canberra.

Carey, A, Evans, M, Hann, P, Lintermans, M, MacDonald, T, Ormay, P, Sharp, S, Shorthouse, D and Webb, N, 2003 Wildfires in the ACT 2003: Report on initial impacts on natural ecosystems, Technical Report 17, Wildlife Research and Monitoring, Environment ACT, Canberra.

Eddy, D, Mallinson, D, Rehwinkel, R and Sharp, S, 1998 Grassland Flora: a field guide for the Southern Tablelands (NSW and ACT) , World Wildlife Fund Australia, Australian National Botanic Gardens, NSW National Parks and Wildlife Service and Environment ACT, Canberra.

Fallding, M 2002, Planning framework for Natural Ecosystems of the ACT and NSW Southern Tablelands , Natural Heritage Trust, NSW National Parks and Wildlife Service and Land and Environment Planning, Canberra.

Landsberg, J 2000, Status of temperate woodlands in the Australian Capital Territory Region, in Temperate Eucalypt Woodlands in Australia; Biology, Conservation, Management and Restoration , Eds RJ Hobbs and CJ Yates, Surrey Beatty and Sons, Chipping Norton, pp 32–44.

National Capital Development Commission 1984, The Ecological Resources of the ACT , Technical Paper 42, National Capital Development Commission, Canberra.

National Land and Water Resources Audit 2002, Australian Terrestrial Biodiversity Assessment 2002 , Commonwealth of Australia, Canberra.

Hogg, D 1990, The Ecological Resources of the ACT: A review of recent information, unpublished report to the National Capital Planning Authority, Canberra.

Pryor, LD 1939, Vegetation of the ACT, unpublished MSc Thesis, University of Adelaide.

Pryor, LD 1954, 'Plant Communities', in Canberra: A Nation’s Capital, Ed. HL White, Australian and New Zealand Association for the Advancement of Science.

Saunders, D, Margules, C and Hill, B 1998, Environmental indicators for national state of the environment reporting – Biodiversity , Australia: State of the Environment, Department of the Environment, Canberra.

Sharp, S, Dorrough, J, Rehwinkel, R, Eddy, D and Breckwoldt, A, in preparation, The Grassy Ecosystem Management Kit: a guide to developing conservation management plans .

Thomas, V, Gellie, N and Harrison, T 2000, Forest Ecosystem Classification and Mapping for the Southern CRA Region , 2 volumes, a report undertaken for the NSW Comprehensive Regional Assessment/Regional Forest Agreement Steering Committee, Project No. NS 08EH, NSW National Parks and Wildlife Service, Southern Directorate, Queanbeyan.

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