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).