Issue: Conserving biodiversity

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Is it growing or going?

The ACT’s biodiversity has faced the four-pronged attack of fire, drought, clearing for suburbs, and weed and pest invasion during this reporting period (2000–03).

While the January 2003 bushfire was dramatic, most of the burnt ecological communities in national parks and nature reserves are expected to re-establish ( see box for more about the fires).

In rural areas, Land Management Agreements have the potential to enable farmers and biodiversity specialists to work together to protect important remnants of a number of ecological communities.

The area in nature reserves and national parks increased by 688 hectares during the reporting period, with the addition of Lower Molonglo. This brings the total conservation area in the ACT to 125,203 hectares (or 53% of the Territory).

The future for biodiversity in areas marked for urban development is less certain. Some remnants of valuable ecological communities could well be destroyed, unless the ACT Government continues to add to the nature conservation system.

Grassy woodlands - going, going...?

The ecological communities at greatest risk in the ACT are grasslands and lowland woodlands, particularly the endangered Yellow Box–Red Gum Grassy Woodland.

By the end of the reporting period there were 10,870 hectares of this endangered woodland in the ACT, of which 2345 hectares were in nature reserves. This is a significant and high quality component of the 25,200 hectares that remain in the ACT and surrounding region.

While the ACT easily meets the Regional Forests Assessments target of retaining 15% of the original extent within its own borders, there is no chance of achieving this target across the region. The remaining 25,200 hectares is only 8.5% of the original regional extent of Yellow Box–Red Gum Grassy Woodland ( Draft ACT Lowland Woodland Conservation Strategy , p84 ).

Despite the regional and national importance of these woodland communities, the threat of clearing for urban development in the ACT continues to be real.

During 2000–03, 17 hectares of the Yellow Box–Red Gum Grassy Woodland ecological community were cleared for urban development. Along with some small areas of other woodlands, a further 85 hectares of paddock trees with little native understorey were cleared in Gungahlin, Dunlop and Tuggeranong.

The ACT Government needs to carefully evaluate when it is time to forgo the time-limited benefits from further property development, land sales and rates in favour of a broader economic base and upholding its regional and national environmental responsibilities.

The Draft ACT Lowland Woodland Conservation Strategy is one important step. It provides an excellent, comprehensive and holistic picture of the relationship between remaining endangered woodlands, other woodlands and secondary grasslands, their conservation value, and actions necessary to achieve conservation goals. The Strategy must be finalised, and its priority tasks resourced and implemented.

Proposals to place 1065 hectares of high quality Yellow Box–Red Gum Grassy Woodland and other woodlands in reserves in East O’Malley, Jerrabomberra Valley and Gungahlin are also commendable. This includes 66 hectares that was originally intended for residential development in East O’Malley.

Despite these gains, more grassland and lowland woodland areas have been lost since the end of the reporting period, with the expansion of Dunlop and sale of 25 hectares for residential development at East O’Malley. Retaining some trees under the Tree Protection (Interim Scheme) Act 2001 does not save ecological communities because it leaves the understorey unprotected.

In the future, many other areas of grassland and lowland woodlands may also be cleared for suburbs if Gungahlin is completed to the full extent shown in the Territory Plan and Spatial Plan.

At risk is up to 660 hectares of endangered Yellow Box –R ed Gum Grassy Woodland fragments, along with 530 hectares of other woodland fragments. As much as 600 hectares of paddock trees with little or no understorey may also be cleared. 1

Yellow Box–Red Gum Grassy Woodland communities may soon be declared nationally endangered under the Environment Protection and Biodiversity Conservation Act 1999. If this happens, then any proposed significant impact on this community will require reference to the Commonwealth.

Fire

The January 2003 bushfires burned 165,000 hectares of the ACT and had the single greatest impact on biodiversity during the reporting period. Some 90% of Namadgi National Park was burned, as was virtually all of the Tidbinbilla and the Murrumbidgee River Corridor Nature Reserves, and about 18% of Canberra Nature Park.

Some of these areas were last burned in 1952 or even earlier.

A relatively small area was burned during the Christmas 2001 fires. Most of this was pine plantations and grazing lands to the west of Lake Burley Griffin, with other smaller fires elsewhere around the ACT. Some 330 hectares of grasslands, paddock trees and lowland woodlands were burned.

Surveys after the January 2003 bushfires raised concerns for a number of ecological communities and species. Sub-alpine bogs, Black Cypress Pine woodland, She-Oak and Callitris riverine communities in the Murrumbidgee River Corridor, and threatened native fish species in the upper Cotter catchment were all affected.

The Northern Corroboree Frog, already in decline, was seriously affected by the January 2003 bushfires. It is now the subject of a captive husbandry program.

The good news is that widespread recovery of fire-damaged ecological communities was seen by the end of 2003. However, regeneration is not well understood and structural change is almost inevitable. The recovery process should be monitored closely, because it is rare to have the opportunity to monitor ecosystem responses to a major disturbance.

Ecological communities defined

A significant achievement during the reporting period has been a new classification of ecological communities for the ACT and surrounding areas. Based on data obtained for the NSW Regional Forests Assessments project in 1997–2000, this classification sets a framework for monitoring ecological communities.

The classification fulfils a recommendation from the 2000 State of the Environment Report and replaces the provisional classification used at that time.

Twenty-eight of these communities occur within the ACT. Virtually all were affected by the January 2003 bushfires, including the 15 communities that occur entirely within Namadgi National Park.

So what else is changing?

A number of other ecological communities and species are under pressure in the ACT but data are limited for many of these. Woodland birds are reported to be on the decline (a trend not confined to the ACT) as are native fish.

Two species – Ginninderra Peppercress Lepidium ginninderrense and Silver Perch Bidyanus bidyanus – were added as threatened species in the ACT. Action Plans for these two species were prepared in 2003 under the Nature Conservation Act 1980 .There were 24 species and two ecological communities in the ACT that were recognised as threatened by the end of the reporting period.

The ACT’s aquatic communities were already under severe strain because of drought-induced reductions in streamflow. Many were impacted further by the 2003 fires. Initial post-fire surveys showed that a number of species were affected, including Two Spined Blackfish Gadopsis bispinosus , Trout Cod Maccullochella macquariensis , Macquarie Perch Macquaria australasica , and Silver Perch Bidyanus bidyanus .

On-going monitoring and further studies will be required to understand long-term re-establishment. The post-fire recovery process should ensure that the mountain streams these fish depend on are well rehabilitated.

Pests an ongoing threat

Pest plant (weed) control emerged as a major land management issue following the drought and January 2003 bushfires. Together with control of pest animals, this remains a major measure to protect biodiversity in the ACT.

Despite major control efforts, weeds such as Chilean Needle Grass Nasella neesiana and African Love Grass Eragrostis curvula continued to spread, threatening lowland communities such as Natural Temperate Grassland. Roads, fire trails and utility easements that facilitate the spread of weeds or create other disturbance can also affect relatively remote areas. Spread of weeds from adjacent urban areas is of particular concern and a threat to lowland ecological communities.

On the positive side, significant progress was made towards controlling a total of 26 weeds (declared, other woody and aquatic) with ten-year weed management plans for a number of species. These activities need ongoing funding and agency commitment.

Also full of promise is the ACT Vertebrate Pest Management Strategy , which is the basis for vertebrate pest control in the ACT.

Some achievements in pest control have been undone by the bushfires. Feral horses, for example, have moved from Kosciuszko National Park into Namadgi National Park through bushland opened up by the removal of dense vegetation during the 2003 bushfires.

This reporting period saw continued community concern about biodiversity impacts of the ‘backyard takeover’ by the Common Myna Acridotheres tristis . An innovative trapping trial for this species of introduced birds has started. This fulfils a recommendation of the 2000 State of the Environment Report.

What does the future hold?

Recovery from fire and the management response to fire are major factors in the future biodiversity of the ACT. While the long-term implications of the 2003 bushfires on biodiversity are unclear, regeneration and regrowth in conservation areas can be expected.

Burnt ecological communities may not be the same as they were before the bushfires. Species composition and abundance may alter and continue to change through the regeneration process.

While simplistic solutions for dealing with fire threat are appealing they could also have far-reaching adverse impacts on biodiversity. The origins, nature and effects of bushfires and management of public lands that are critically important for biodiversity conservation have become the subject of much public debate and of formal inquiries such as the McLeod Inquiry. 2

Advice on biodiversity conservation needs to be an integral part of the planning for fuel hazard reduction activities. In the wake of the bushfires, there is pressure (supported by recommendations from inquiries) to undertake more fire fuel hazard reduction, to expand the fire-trail network, create fire protection zones and to change the landuse in previously vegetated areas. An extensive program commenced in autumn 2003.

Such activities have implications for biodiversity conservation through habitat destruction and modification. A holistic management strategy is needed to guide hazard reduction activities and respond appropriately as the burnt areas regenerate.

A key issue is the ongoing threat to the natural integrity of woodland and grassland remnants from adjacent landuses. Weeds and pest animals may jump fences, understorey is removed from woodlands to help reduce the threat of fire, and significant areas continue to be cleared for urban development. This highlights the need for high-level protection and management.

Commissioner's recommendations

In consultation with the Commissioner for the Environment, the ACT Government should:

  • immediately develop and resource long-term research and monitoring programs of at least 30 years duration into post-fire recovery of terrestrial and aquatic components of natural and modified ecosystems as part of a joint program with other research providers in States affected by fire
  • seek funding for the long-term research in the above recommendation from the Commonwealth Government on the basis of the National Research Priority ‘an environmentally sustainable Australia’, announced in December 2002
  • ensure that biodiversity conservation is always integral to ACT Government planning and management of landuse changes, post-fire recovery programs, and fire prevention programs such as fuel hazard reduction programs, expansion and management of the firetrail network, creation of fire protection zones
  • assess the contributions of existing ACT Government pest plant control programs to achieving pest plant control, biodiversity conservation, and catchment management objectives, and if appropriate, trial alternative programs
  • implement an appropriate post-fire works and management program to protect water supply catchment, aquatic habitat and nature conservation values of the upper Cotter River, Murrumbidgee and Molonglo River valleys, and their tributaries
  • provide appropriate resources and support for improving the comprehensive, adequate and representative system of protected lowland woodland and grasslands in the ACT as outlined in the Draft Lowland Woodland Conservation Strategy (as detailed in the priority tasks of Table 6.2 of the Strategy), and for ongoing management of these ecosystems.

Some recommendations from this issue are found in other issues because of the interactions between various components of the environment.

End Notes
1
It is recognised that these areas do not all have the same conservation value
2
McLeod, R. 2003 The Inquiry into the Operational Response to the January 2003 Bushfires , ACT Government, Canberra.

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