ACT State of the Environment 2007

Land degradation

Summary

Since the 2003 State of the Environment Report, the broad effects of drought combined with existing pressures have seen land degradation through erosion become more visible across the ACT. In response to this, few though strong steps have attempted to address the ACT's land degradation issues. The most noteworthy of these steps is the restoration plan for the Lower Cotter Catchment.

In the ACT, the area and proportion of land degraded by erosion is unknown. Importantly, the full impact of the drought and the fires remains to be assessed across the whole of the affected area. However, some progress has occurred during the reporting period with the production of management guidelines produced to set management standards and practical guidelines to, for example, lessen the impact of roads and management operations on catchments.

Further progress has been made towards expanding knowledge on salinity issues in the ACT. Indicative of upstream land degradation though salinity, measurements of electrical conductivity in streams has provided a much-needed indication of dryland salinity in the ACT.

What the results tell us about the ACT

The ACT is fortunate that conservation is the dominant form of landuse ( see Landuse indicator). However, outside the conservation estate there are several visible hotspots of land degradation from other forms of landuse in the ACT. While these visible areas are confined, little remains known about the full extent of land degradation issues and impacts across the ACT.

Early in the reporting period, the impacts of the drought and consequent bushfire resulted in large tracts of land becoming degraded through erosion.  Much of this, especially in conservation areas is due to a natural process with the land only remaining degraded for a short period of time.  For example, erosion and water quality problems downstream of the degradation persisted for only the first year or so during the reporting period.

While we are aware of the visible forms of land degradation such as erosion, the condition of much of the ACT is not known.  Outside the fire affected areas, little is known on the affect of urban and industrial developments on land condition and degradation. This is also the case for the ACT rural lands.  Degradation mapping and monitoring across the whole of the ACT has not occurred.  With better information on land conditions and degredation land management resources could be applied more effectively and efficiently.

Salinity

The ACT now has three years of baseline salinity monitoring data (salinity measured continuously at the Murrumbidgee and Molonglo Rivers as they enter the ACT and at the Murrumbidgee as it exits the ACT).  A baseline salinity model to meet one of the requirements of the Murray Darling Basin Salinity Management Strategy has been produced. Additionally there is now a continuous salinity monitoring network throughout the ACT that has been collecting data for about a year. Baseline mapping of salinity (as indicated by stream Electrical Connectivity) will be finalised by the end of November 2008.

The Lower Cotter Catchment

Data from the Lower Cotter Catchment indicate some 7.6% of the storage capacity has been lost to sedimentation since 1951. At least 40% of the capacity loss occurred after the 2003 bushfire and during increased forestry activity to salvage the former pine plantation (Ecowise 2006). The water quality issues arising from this are discussed in the Water quality (lakes and rivers) indicator.

A shift in land management practices has been needed in order to address this problem. The most significant shift was the decision to discontinue the commercial forestry operations in the Lower Cotter Catchment. Commercial forestry practices and agriculture are recognised as practises that degrade land.  This decision recognised that the Lower Cotter Catchment needed to be managed primarily to give priority to its significant role in influencing water quality in the catchment and conserving native ecological landscape values. These practices will be guided by the Clean Water, Healthy Landscapes: Lower Cotter Catchment Draft Strategic Management Plan. The strategic management plan focuses on a return to native forest in the lower Cotter. This plan is yet to be formally approved by the ACT Government.

After the draft plan was completed, the former Environment ACT (now incorporated into Parks, Conservation and Lands, TAMS) established a dedicated coordination position to manage operations. A number of implementation plans were developed to guide works in relation to road and sediment control, fire management, vegetation management, and monitoring and research.

During mid-2006, following the establishment of the Restoration Deed between the former Environment ACT and ACTEW Corporation, the rehabilitation works expanded greatly and the focus moved from Pierces Creek to the Uriarra forest on the western side of the Cotter River. The Deed provides a framework for ACTEW's participation in, and funding of, catchment restoration works. The Deed has proved very successful in ensuring efforts towards a holistic and cooperative approach to catchment management.

Community involvement has been key to the replanting program in the Lower Cotter Catchment. To date, over 1800 volunteers have been directly involved in planting over 25,000 plants.

The scale of the task to rehabilitate 3500 hectares of former pine plantation should not be underestimated and has led to use of a variety of methods. Some traditional methods such as the mechanical removal of standing dead pines and the use of machinery to prepare sites for revegetation have attracted some controversy. However, alongside these methods, which were developed for forestry operations, a range of low impact methods are also being applied. For example, removal of pine wildlings was achieved by manual lopping of individual trees, without the need for machinery or herbicide. Where possible, gully erosion was treated using low impact manual or small machine methods at the head of gullies. Revegetation was done by air and manually and local species were used to maximise survival rates. In addition, natural regeneration in many parts of the catchment was better then expected, requiring only weed control to give native species an advantage.

Despite this progress, little reporting or review of the progress or effectiveness of rehabilitation efforts was made available to the public. Additionally, such reporting or review may provide the opportunity to revisit work plans to adaptively identify data gaps and re-address rehabilitation priorities or hotspots within the catchment. 

It is understood that in future, fire may be used for ecological management, weed control and/or hazard reduction. Land management programs need to be consistent with the Lower Cotter Catchment Strategic Management Plan and supporting Implementation Plans, with catchment protection as the primary objective. While the community has increased its knowledge of rehabilitation in the ACT after as a result of recent experiences in the Lower Cotter Catchment and Boboyan Pines in the Namadgi National Park, there is still much to be learnt.

The Pine Plantation Estate

Outside the boundaries of the Lower Cotter Catchment, much of the former forestry plantations consumed by the 2003 bushfire remain degraded.  During the early reporting period, many of these sites have been prepared and planted for commercial forestry operations. Monitoring of these areas is needed to ensure the commercial use does not have further significant impacts on natural values.

While areas of the former pine plantations of the Molonglo Valley and Stromlo Forests have been prepared and replanted with pine species, the ACT Government is reconsidering use of the areas following the 2001 and 2003 bushfires. With much public interest, the lands of Mount Stromlo have been converted to a multiuse sporting facility, the Stromlo Forest Park. While the lands remain degraded following the 2001 and 2003 bushfires, work to rehabilitate the area is progressing.

The former forests of the Molonglo Valley were salvaged during the reporting period. Some areas were replanted with pine species; however, much of this land remains degraded with ground bare of vegetation leaving it vulnerable to erosion. The ACT Planning and Land Authority is investigating the long-term landuse of the area.

In east of the ACT, the Kowen Forest remains a commercial pine plantation. No data on degradation or a plan of management for this site was available at the time of writing this report.

Unsealed Roads

Unsealed roads on slopes, particularly if frequently trafficked, have long been recognised as a form of land degradation. In addition to the soil erosion and biodiversity loss and fragmentation, less reported degradation includes the potential risk to lands through weeds and feral animal infestation, and bushfire through arson. However, roads are essential for management purposes and given this, there is a need to focus on having only roads that are essential.

An estimation of unsealed roads in the ACT by ACT Planning and Land Authority indicates approximately 60 km of unsealed roads are maintained (yearly) by Roads ACT. This includes the Boboyan, Brindabella, Mt Franklin, Bendora Dam roads.  Parks Conservation and Lands, TAMS manage an additional 1900 km (approximately) of roads in the Namadgi National Park, the nature reserves and pine forests. The maintenance interval for these roads falls between one and five years, depending on the type and use.  While sealing these roads is not necessary, awareness of their role and affect should be reflected in their management and intensity of use.

During the reporting period, work to remove unnecessary roads from the Lower Cotter Catchment progressed. This work will significantly progress the land management objectives of improved drinking water quality and protection of aquatic ecosystems of the river, especially of reversing the habitat degradation of threatened fish communities.

The number of forest roads will decrease in the Lower Cotter Catchment and Stromlo Forest, as the management focus of these sites changes from commercial plantation to water conservation, recreation and possibly urban. Recreational activities in water supply catchments will require clear definition to ensure the protection of water quality as a first priority.

Land Management Guidelines   

Three documents (the Silviculture Manual (2006), the Roading Manual (2006) and the ACT Code of Forest Practice (2005)) that address aspects of land degradation were produced within the various land management agencies during the reporting period. The documents set management standards and practical guidelines for commercial forest operations in the ACT.

These documents are due to be reviewed during 2008.  It is understood that the review will reflect and incorporate government and community values, research findings, and experience gained during implementation. An overall ACT land degradation analysis presented on a map would provide valuable additional information for land managers and community groups who undertake land restoration activities.  It would also assist the ACT Government in addressing new issues facing the landuse and landscape management since the 2003 fires, as an ACT wide land degradation analysis is needed.  The review of the above documents in 2008 could be expanded to may consider an ACT wide guideline framework for land management operations.

Sources

Ecowise (2006). GIS Analysis of the Cotter Dam Reservoir Bathymetry. Report to ACTEW Corporation.

ACT Government (2005). ACT Code of Forest Practice. Version 1.

ACT Government (2006). Roading Manual. Version 1.1

ACT Government (2006). Silviculture Manual. Version 1.

TAMS Territory and Municipal Services and ACTEW

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