Issues

• Values: what do we need to sustain?
• Constraints
• SoE and Limits to Knowledge

• Atmosphere
• Land
• Inland Waters and Wetlands
• Biodiversity
• Settlements
• Cultural Heritage
• Coastal, Estuarine and Marine

• Response Instruments
• Summary of Report Recommendations
• Strategic Recommendations
• Conclusion

This sustainability review of the Land Chapter summarises the chapter content and provides an overview from a 'sustainability' perspective. A similar framework is used for all chapters within the 'Sustainability Review'. This provides a consistent way of comparing the major findings across the SoE Report within this final chapter. The 'Sustainability Review' provides the highest-level summary of each of the chapters. More detailed information is provided within each of the major theme chapters. Links are provided to the issue reports referred to in the 'conditions and trends' section below.

The content is organised under five major headings from a higher-level summary in the section entitled 'vision' to comparatively more detail in the section on 'conditions and trends' and 'what has been achieved'.

1. Objectives: Presents an objective for land resources in Tasmania.
    
2. Integrating concepts or indicators: Reports on any integrating concepts or indicators provided in the chapter.
    
3. Capacity to assess and measure: Reports on capacity to assess conditions and trends for this chapter theme.
    
4. Conditions and trends: Presents a summary of the key findings of the chapter, with links back to the related Issue Reports for further detail.
    
5. What has been achieved, 1998-2003: Presents a summary of key initiatives over the five year review period for the Second SoE Report.
    

Land resources objective

The objective for land resources reflects the vision established by Tasmania Together and the key findings of the Land Chapter. Applicable Tasmania Together goals and standards include: 'To maintain or improve natural heritage including biodiversity, geodiversity and landscapes' (Goal 22). For further information see Tasmania Together Goals applicable to the Land Chapter and Tasmania Together.

The productivity, scenic and wilderness values of the landscape is maintained through a mosaic of land uses and natural land cover across land uses and tenures, which recognises the consequences of threatening processes for land and the downstream consequences of these processes for catchments, coasts, and estuaries.

Integrating concepts or indicators

While there are a number of threatening processes and their consequences in the chapter, much of it can be summarised in terms of maintaining land cover. Priorities for maintaining land cover can be determined based on the susceptibility of particular areas to degrading processes such as soil structural decline, water erosion, and acid sulphate soils. Additional priorities should be based on priority vegetation communities and productivity of soils for agricultural use (land capability).

Capacity to assess and measure

The capacity to assess and report on conditions and trends across land resource issues in Tasmania is variable. However, a new understanding has emerged of some significant threatening processes affecting land resources, including salinity, acid sulphate soils, and acid mine drainage. In particular, preparation of this SoE Report has benefited from the National Land and Water Resources Audit, which prompted a number of co-ordinated national data gathering initiatives and consistent presentation of this information in the Australian Natural Resource Atlas. The SoE Report has also benefited from specific Natural Heritage Trust funded reports such as those on acid sulphate soils and acid mine drainage.

Considerable work has been undertaken since the last SoE Report, yet it is clear that there is much more to be done to fully address the wide range of land issues presented in this report. At a Statewide scale, soil condition mapping (particularly in agricultural areas), improved landscape inventory, improved capacity to detect changes in vegetation cover, a comprehensive survey of rural tree decline, a survey of the extent of soil erosion and soil structure decline, and an update of the 1995 National Wilderness Inventory are identified as required.

While considerable work has been undertaken on the issue of geoconservation, further work is required to assess the condition and conservation status of a number of significant sites. Valuable progress is being made on the issue of salinity, which would be enhanced with more comprehensive groundwater monitoring. Many issues such as rural tree decline, salinity, soil erosion and soil structure decline have positive actions in place, but require continuing research to improve management responses. Management responses to acid sulphate soil disturbance and acid mine drainage issues need to be more effectively prioritised.

Conditions and trends

The Land Chapter in this SoE Report reviews land resources under two broad topics: condition and threatening processes. Within these topics, 11 issues are examined - land tenure, land use and land cover; soil condition; scenic landscape condition; geodiversity and geoconservation; wilderness; salinity; rural tree decline; soil erosion; soil structure decline and compaction; disturbance of acid sulphate soils; and acid mine drainage. More detailed information is provided in the Land Chapter. Weeds, pests and diseases are reviewed in the biodiversity chapter of the 2003 report.

Land Tenure, Land Use and Land Cover: Environmental issues affecting both aquatic and terrestrial environments in Tasmania are consequences of human-induced changes to land cover. There has been a general trend towards more intensive production of commodities providing higher yields and higher profits. This is achieved through intensification in the form of increased irrigation on agricultural land and plantation development in State and private forests. Various measures of intensification are provided in the body of the report.

Soil Condition: Soil characteristics, such as drainage status, texture, colour, pH, structural strength and nutrient status cause soils to have greater or lesser capacity to respond to land use management stress. Recent work by Cotching et. al. (in prep.) showed signs of soil structure decline associated with long-term cropping on one third of paddocks on the four soil types investigated. Extrapolation of the results suggest that as much as 38,000 ha of cropping land could be experiencing similar levels of soil structure decline. The work indicates that, on the red Ferrosols of northern Tasmania, yield losses for potatoes resulting from soil structure decline could amount to 14,500 tonne per annum, or over $3.2m per year.

Scenic Landscape Condition: The visual impact of landscape development is scale and context specific and is dependent on the scenic landscape techniques that are used. The area of particular land use types within landscape areas provides one perspective on the changes that may affect landscapes in Tasmania. Land use types considered include housing completions and plantation area. For example, the largest plantation area coverage occurs in the North-West Hills and Plains Landscape Character Unit which contains 68,122 ha of softwood and hardwood plantation. This represents about 16.1% of the area of this landscape unit . The next largest plantation area coverage occurs in the North-East Highlands Landscape Unit, which contains 55,474 ha of softwood and hardwood plantation. This represents about 8.5% of the area of this landscape unit.

Geodiversity and Geoconservation: Geological (833 sites), geomorphological (762 sites) and soil (69 sites) sites of geoconservation significance are listed on the Tasmanian Geoconservation Database as of 2003. Approximately 20-30% of the three types of sites are secure, while up to 43% of these sites are either endangered, threatened or have a potential threat. The conservation status of 40-50% of these sites is unknown, as is the condition status of 40-70% of these sites.

Wilderness: Tasmania has 1.9 million hectares of high quality wilderness, and the 95% in formal and informal reserves is an increase of 9% (176,700 ha) since 1996. Much is contained within World Heritage Area (WHA), and the unreserved 5% is mainly located in areas subject to multiple use forestry. However, because the 1995 National Wilderness Inventory has not been updated, it is difficult to discern trends in wilderness condition and extent. At a finer scale, deterioration of walking tracks in the World Heritage Area is an issue, with the total number (960) and length (3,100 km) exceeding the State's capacity to manage them all to a consistent standard.

Salinity: The Salinity Audit reported that the area of salt affected agricultural land in 2000 was estimated to be 53,500 ha or 3% of Tasmania's agricultural land. Visual signs of salinity are evident in 20 out of the 29 Tasmanian municipalities, with the worst affected being the Northern and Southern Midlands, Central Highlands, and Dorset municipalities. The area of salt-affected agricultural land in Tasmania is estimated to increase to 94,000 ha by 2050 (Bastick and Walker 2000). Annual losses to agriculture are estimated at $5.4 M.

Rural Tree Decline: Tree decline is the most extensive form of land degradation in Tasmania, estimated in 1992 to be affecting 42% of private land (861,000 ha), with the worst areas being in the Midlands and the upper Derwent Valley (Grice 1995). No systematic Statewide survey has been conducted since the 1992 survey, and this only covered private land.

Soil Erosion: Sheet, rill, gully, tunnel and streambank erosion have been documented in particular regions of the state. Recent work has found that erosion from intensively cropped catchments in north-west Tasmania is resulting in off-site environmental degradation such as high stream turbidity levels and suspended sediment loads. Measurements were made at both catchment and paddock scales with the highest turbidity values recorded in run-off from fallowed paddocks. An Index was obtained from Landsat data to identify areas that may be prone to water erosion. This information has been applied to report against an indicator of erosion risk.

Soil Structure Decline and Compaction: Grice (1995) estimated that 15% of private land in Tasmania is susceptible to moderate to severe soil structure decline, and there are no updated data since this 1992 survey on private land.

Disturbance of Acid Sulphate Soils: Acid drainage from disturbance of these soils is a particular concern. A conservative estimate shows that at Mella, about 1,000 ha of acid sulphate soils may be contributing acid drainage to Scopus Creek during periods of peak drainage flow. Swamp environments similar to Mella also occur at Togari, Montagu and Brittons. King Island, north-east Tasmania, and Flinders Island showed some indications of potential problems. On King Island iron-rich sediments occur in the underlying coastal marine sediments with the potential to host acid sulphate soils.

Acid Mine Drainage: Acid mine drainage results from the oxidation of sulphide-bearing rocks. It is recognised as one of the major sources of heavy metal pollution in many waterways near metal-mining sites in Tasmania. There are over 4,000 recorded mineral activity sites in Tasmania and of these about 681 sites are classified as metal-related abandoned mines of various categories. Most of the large metaliferous mines in Tasmania are on the west coast, but there are many abandoned mines sites elsewhere in the State (e.g. north-east).

What has been achieved, 1998-2003

• A standard classification of land use and a land use map of Tasmania has been finalised in 2003 as part of the National Land and Water Resources Audit.
   
• Soil management guidelines have been prepared (Hamlett 2002), which complement a number of DPIWE technical documents on land management, including Managing Tasmania's Cropping Soils (Chilvers 1996).
   
• In forestry areas the main soil types have been defined; new guidelines are being trailed which require increased soil protection next to headwater streams.
   
• Base mapping has improved through the update of a 1995 Karst Atlas for the State in 2002, and with development of a Coastal Geomorphic Types database. A major project on classification of Tasmanian fluvial landform systems has been in progress.
   
• The Tasmanian Salinity Audit was undertaken, and DPIWE has commenced the development of a Tasmanian Salinity Strategy due for completion in 2003.
   
• Research has been undertaken at the University of Tasmania and the Cooperative Research Centre for Sustainable Production Forestry into the causes of rural tree decline.
   
• A significant amount of work has been undertaken by landowners and managers to re-establish trees in affected areas, supported by national programs such as Landcare and One Billion Trees.
   
• The National Heritage Trust 'north facing slopes project' has provided over 100 km of fencing materials to fence off 1,890 ha, to encourage improved sheep grazing management on highly erodible north facing slopes. A mulched rip lines erosion control technique has been used in sloping land in north-west Tasmania to protect 400 ha in 2001 and 600 ha in 2002.
   
• A number of research studies into soil compaction in forest soils have been undertaken at the Warra Long Term Ecological Research site in the Southern Forests.
   
• An NHT supported project entitled 'Minimising Land Degradation and Salinity Risk using Resource Information' is investigating degradation risks including soil structure decline due to intensified land use at three pilot areas around the State.
   
• Understanding ofacid sulphate soils in Tasmania has improved since the survey, mapping and report undertaken by Gurung (2001), which was funded by the Natural Heritage Trust and managed through Mineral Resources Tasmania..