Natural Values Chapter
Geodiversity
Issue Report


Background

Mt Anne, Southwest Tasmania, Tasmanian Wilderness World Heritage Areainternal SOE link to larger image

Source: Photograph courtesy of Internal linkMcPhail 2006

Geodiversity is the natural range (diversity) of geological (rocks, minerals, fossils), geomorphological (landform and processes) and pedological (soil) features (Internal linkGray 2005; Internal linkEberhard 1997). It includes their range of assemblages, relationships, properties, interpretations and systems and is an essential foundation for soil health and biodiversity. For example, a tiny islet or rocky outcrop found 26 km off the south-east coast of Tasmania in the Tasman Sea called Pedra Branca Rock, is the only place in the world where the endangered Pedra Branca skink (Niveoscincus palfreymani) lives. Without this geological landform the skink would not exist (Internal linkPWS 2008). In addition, knowing more about our geodiversity helps us to interpret change processes in the landscape such as fluvial and coastal erosion. Geodiversity also has an intrinsic value and it plays a vital role in the community's sense of place, belonging, history and well-being. A number of people value highly the aesthetic and intrinsic values of geological features.

Many of the landscapes that make up Tasmania's geodiversity are a result of the underlying ancient rock structures of very old Paleozoic rocks (524–300 mya) to the west and old Mesozoic rocks (300–140 mya) to the east of the State. They are also the result of modifications of the older Paleozoic and Mesozoic topography by Tertiary block faulting (that began about 65 mya). The distribution of these ancient rock formations are shown below in Map A. Fluvial processes shaped the land surface during the Tertiary era etching out geological structures, including faults and dolerite sills in eastern and central Tasmania, while fold structures and granite bodies in western Tasmania were exposed after flat-lying sediments and dolerite sills were removed by erosion. Some overlying structures, now long gone, are still reflected in western rivers that flow east-west across the grain of the now exposed folded basement rocks. Basaltic lava flows modified Tertiary drainage patterns, giving rise to the precursors of the modern drainage system. The Tertiary landforms were rapidly modified by energetic glacial, periglacial and glacio-fluvial processes during the last few million years, but are today being only slowly modified by ongoing fluvial processes. Glacial and periglacial landforms in Tasmania are relict (fossil) features produced by processes that are no longer active (the most recent glaciation probably began some 25 tya and reached its peak at roughly 19 tya). Glaciated landforms in the State are shown in Map B. Inland aeolian features in eastern Tasmania that have been deposited or eroded by the wind from the last glacial age are also commonly found inland as deflation hollows and associated lunettes. These landforms are shown in Map C. Collectively, these ancient landforms form a foundation for Tasmania's geodiversity and they cannot be regenerated if damaged.

Ancient rock landforms

Ancient rock landformsinternal SOE link to larger image

Glaciated landforms

Glaciated areas in Tasmaniainternal SOE link to larger image

Aeolian landforms

Aeolian landforms in eastern Tasmaniainternal SOE link to larger image

Geodiversity is an important part of the State's natural heritage. The term first appeared in articles from Tasmania in the mid-1990s and has now become accepted internationally by many environmental agencies and organisations (Internal linkSharples 1993; Internal linkDixon 1995; Internal linkKiernan 1996). Examples of geodiversity in Tasmania include the following landforms.

Aeolian landforms

There are many geomorphological features in Tasmania that have been formed by aeolian processes. Relict features that have been mapped are commonly found inland such as the lunettes at Moulting Lagoon on the east coast, Double Lagoon on the Central Plateau, Woodstock Lagoon near Longford and the Ellinthorp lunette cluster between Lake Sorell and Ross. Other aeolian features located to the west and south of the State have yet to be mapped. There are also active coastal dune systems (often parabolic) that overlie predominantly linear dunefields of late Pleistocene era (about 10,000 years ago) such as the Henty Dunes near Strahan, the Anderson Bay Waterhouse dunefield, and transgressive sand sheets at Interview River.

Moulting Lagoon lunette

Deflation basin and lunette at Moulting Lagooninternal SOE link to larger image

Double Lagoon lunette

Lunette at Double Lagoon on the Central Plateauinternal SOE link to larger image

Interview River dunes

Interview River transgressive sand sheetsinternal SOE link to larger image

Aeolian landforms are highly erodable and vulnerable to changes in the environment. For example, some relict aeolian features have been partially re-activated by recent land degradation. Wind erosion is particularly prevalent in dry environments including coastal areas, the midlands, and areas of poor vegetation cover and inappropriate land use. Despite lying in the path of the 'Roaring Forties' and having higher average wind speeds than the mainland states, Tasmania has not been overly susceptible to wind erosion (Internal linkDPIPWE 2009). However, significant degradation of the land resulting from wind erosion is difficult to detect. It is predicted that climate change will lead to windier and drier conditions, and, when coupled with more intense equinoctial wind events, may increase erosion of aeolian landforms and other geodiversity. More information on wind erosion is provided in the embedded document Internal linkWind Erosion in Tasmania.

Woodstock Lagoon lunette

Woodstock Lagoon lunetteinternal SOE link to larger image

Ellinthorp lunette cluster

Ellinthorp lunette clusterinternal SOE link to larger image

Coastal landforms

Bays, lagoons and boulder and sand beaches that are found around Tasmania's coastline, as well as Australia's highest sea-cliffs found on the hard rock coasts of the Tasman Peninsula. There are also low energy systems with extensive tidal flats such as the symmetrical spits and tidal inlet at Stanley.

Crescent Bay

Crescent Bayinternal SOE link to larger image

Kenneth Bay spit

Kenneth Bay spitinternal SOE link to larger image

New River Lagoon

New River Lagooninternal SOE link to larger image

Egg Beach, Flinders Island

Egg Beach (boulder beach) on Flinders Islandinternal SOE link to larger image

Tasman Arch

Tasman Arch on the Tasman Peninsulainternal SOE link to larger image

Cape Pillar sea-cave

Drowned sea-cave at Cape Pillar on the Tasman Peninsulainternal SOE link to larger image

Coastal landforms can be more or less resilient to environmental and climatic change. However, these highly exposed environments are generally vulnerable to sea-level rise, coastal inundation and/or the drying of estuarine areas prone to reduced freshwater runoff. For example, scientists are observing changes in some coastal landforms such as coastal recession and the exposure of peat layers to beach cliff forms at Ocean Beach on Tasmania's west coast. Coastal recession processes at Ocean Beach are illustrated in the following diagram.

Coastal recession processes

Coastal recession processes at Ocean Beach, West Coast of Tasmaniainternal SOE link to larger image

Glacial landforms

Spectacular erosional landforms have developed in Tasmania as a result of late Cenozoic glaciation (about 2 mya –10 tya) on multiple occasions. For example, we have distinctive mountain landforms that have developed on columnar dolerite substrates at Cradle Mountain. In addition, ice cap glaciation of massive dolerite sills has left a profusion of shallow tarns across the Central Plateau. Moraines are also found in lowland settings in the centre and west of the State such as those found at Federation Peak.

Cradle Mountain

Cradle Mountaininternal SOE link to larger image

Central Plateau tarn

Rock-basin tarn on the Central Plateauinternal SOE link to larger image

Federation Peak moraine

Moraine at Federation Peakinternal SOE link to larger image

These landforms, along with periglacial landforms, are generally well reserved in Tasmania and are also comparatively resilient to environmental and climatic change in human time scales.

Periglacial landforms

Many highland landforms have been shaped by periglacial freeze-thaw conditions. Extensive relict blockstreams encircle the higher dolerite peaks of central and north-east Tasmania such as those found at Western Bluff on the Great Western Tiers. There are also active periglacial systems found on the higher peaks in Tasmania such as at Nevada Peak and frost hollows that occur in plateau areas including Lake Augusta.

Great Western Tiers

Blockstreams at Western Bluff on the Great Western Tiersinternal SOE link to larger image

Nevada Peak blockfield

Periglacial blockfield at Nevada Peak in southwest Tasmaniainternal SOE link to larger image

Lake Augusta polygons

Sorted polygons (patterned ground) at Lake Augustainternal SOE link to larger image

Uplift landforms

Western Tasmania has been one of Australia's most active neotectonic regions, with late Cenozoic uplift rates in the order of 100 m/million years. We have spectacular flights of marine fluvial terraces such as those found at Birches Inlet. We also have Pleistocene fault scarps (from about 1.8 mya –10 tya) that are tens of metres high in the south-west such as the unnamed scarp on the D'Aguilar Range and the fault line at Lake Edgar.

Birchs Inlet marine terraces

Birchs Inlet marine terrace sequenceinternal SOE link to larger image

D'Aguilar Range fault scarp

Quaternary fault scarp at D'Aguilar Range in the western Tasmanian Wilderness World Heritage Areainternal SOE link to larger image

Lake Edgar fault scarp

Quaternary fault scarp at Lake Edgarinternal SOE link to larger image

Uplift and erosional landforms are also found on Tasmania's offshore islands. For example, Macquarie Island has been formed by marine erosion processes such as wave erosion as it has risen above sea-level. The island has been squeezed upwards from the oceanic crust and evolved in the Oligocene–Miocene era (between 30–11 mya) as a spreading ridge (Internal linkPWS 2008). It is the only known example of oceanic crust being uplifted as a result of transpression at an ocean-ocean plate boundary. This geological process has resulted in the rocks being far less deformed than similar rocks on other islands and elsewhere. Macquarie Island also has a series of raised beaches or areas eroded by waves at altitudes ranging from 6–400 m that emerged above sea-level approximately 600–700 tya. In addition, earthquakes and extensive faulting have triggered landslip events and shaped the coast, created fault dammed lakes and controlled the location of major landforms. On the basis of its outstanding geomorphic features, Macquarie Island was inscribed on the World Heritage List in 1997 (see Internal linkDEWHA 2008).

Evolving fluvial landforms

Fluvial landforms and rivers take many different forms and they are related to strong east-west climatic gradients, topographic variety and diverse geology. There are spectacular superimposed gorges such as those found on the Franklin River and broad, deep estuaries are found in their lower reaches such as those on the Gordon River. Sinuously meandering gravel bed streams also wind across Tertiary conglomerates (formed between 65–1.8 mya) such as the Sorell River that meanders south of Macquarie Harbour. In addition, distinctive 'broadwater' sequences, with repeating pool, fan/splay and meandering reaches have developed in deep, dispersive silts and clays in the midlands such as those found on the South Esk River. The geomorphology of fluvial landforms link changes in hydrology with changes in catchment sediment budgets.

Gordon River meanders

Lower Gordon River meandersinternal SOE link to larger image

Sorell River meanders

Sorell River meanders south of Macquarie Harbourinternal SOE link to larger image

Macquarie Island meanders

Meandering peat stream on Macquarie Islandinternal SOE link to larger image

Fluvial landforms are comparatively more susceptible to environmental and climatic change and human disturbances. These landforms have been increasingly affected in recent times because drought conditions have resulted in reduced streamflows and increasing pressure by water users on water resources. In addition, there have been more episodic rainfall events that potentially increase surface runoff and erosion. Splash erosion or rain drop impact represents the first stage in the fluvial erosion process. More information on water erosion processes, including streambank erosion, is provided in the embedded document Internal linkWater Erosion in Tasmania.

Karst

Karst landscapes have distinctive landforms and drainage characteristics resulting from the relatively high solubility of certain rock types, notably limestones and dolomites, in natural waters where erosion has produced fissures, sinkholes, underground streams and caverns. They are commonly regarded as special and spectacular, and worthy of conservation. They also provide specialised habitats for a variety of organisms and they contain aquifers. The dependence of karst processes on natural water flows means that karst is highly sensitive to drying in the climate and human activities that alter natural water chemistry, sediment content and flow regimes.

Tasmania's karst is diverse and spectacular. Mountain karst systems include the Vanishing Falls in the south-west and the Annakananda doline on the Mt Anne north-east ridge. Coastal karst in aeolian calcarenite is common on Bass Strait islands, such as the tufa terraces found at Boggy Creek on King Island. The State also has many spectacular karst cave systems including one of Australia's best decorated caves — the Kubla Khan cave system at Mole Creek. This cave has many chambers and stream passages and is decorated with large columns, forests of stalactites and stalagmites and rimstone dams more than 2 m high (Internal linkHamilton-Smith and Finlayson 2003). Other significant cave systems include Gunns Plains Cave; Khazad-Dum in Mount Field National Park (one of the deepest potholes in Australia); those found in the Mole Creek Karst National Park; and others in the south of the State such as Exit Cave (the longest known cave in Australia), Midnight Hole (a 162 m vertical cave that forms part of Mystery Creek Cave) and Newdegate Cave (including a thermal pool at Hastings) (see Internal linkPWS 2006).

Vanishing Falls streamsink

Vanishing Falls karst streamsink in the Southwest National Parkinternal SOE link to larger image

King Island tufa terraces

Tufa terraces at Boggy Creek on King Islandinternal SOE link to larger image

Flinders Island coastal karst

Coastal Karst on Flinders Islandinternal SOE link to larger image

Mt Anne doline

Annakananda doline (glaciokarst) on the Mt Anne northeast ridgeinternal SOE link to larger image

Dismal Swamp doline

Dismal Swamp dolineinternal SOE link to larger image

Damper Cave

Damper Cave at Precipitous Bluff in southwest Tasmaniainternal SOE link to larger image

Kubla Khan Cave

Jade Pool in the Kubla Khan Cave at Mole Creekinternal SOE link to larger image

Exit Cave

The Ballroom in Exit Cave at Ida Bayinternal SOE link to larger image

Midnight Hole

Midnight Hole in Mystery Creek Caveinternal SOE link to larger image

Karst often drains through natural subterranean conduits, some of which become caves that are large enough for humans to enter. These complex surface and subsurface drainage and landform types are known as karst systems. Geological structures rather than surface contours are likely to control directions of flow in karst, and there are many examples in Tasmania of major topographic drainage divides being breached by subsurface karst streams. As a consequence, specialised techniques (including water tracing) are often required to map flow directions and catchment boundaries in karst.

Karst systems are highly susceptible to changes in upstream catchments and altered water balances. However, any changes, such as declining streamflow from the catchments, can take time before they are expressed in karst formation. Lags in the expression of ecosystem changes can result in karst systems appearing to be more resilient and having inherent buffers to altered environmental conditions. Delayed cumulative impacts to karst systems have the potential to be significant and long-lasting. Given their environmental sensitivity, karst systems can provide an indication about the condition of the catchments they depend upon.

Geoconservation

Although landforms and geological features are commonly thought to be robust, many aspects of geodiversity such as cave systems, sand dunes, river features, moraines, soils and fossil sites are highly susceptible to damage. More information on geodiversity can be found though the Department of Primary Industries, Parks, Water and Environment (DPIPWE) External linkGeoconservation website.

Geoconservation is 'the conservation of geodiversity for its intrinsic, ecological and (geo)heritage values' (Internal linkEberhard 1997). It is complementary to bioconservation in that it seeks to conserve the natural non-living aspects of the natural environment, as an integral part of a balanced approach to nature conservation. Geoconservation focuses not only on conserving bedrock geological features, but also landforms (geomorphology) and the natural integrity of active geomorphic processes such as karst, fluvial and coastal systems (Internal linkHoushold and Sharples 2008; Internal linkPemberton 2007; Internal linkSharples 2001). Using the terms 'geodiversity', 'soil diversity' and 'biodiversity' helps to indicate that our natural environment consists of living and non-living components (see also Internal linkGray 2005). When taken together, these components can help to promote a more holistic approach to nature conservation than the traditional biocentric focus. Moreover, geoheritage refers to those specific features, landforms, soils or systems of geoconservation value that is of value in its own right or as part of a natural process. Geoheritage places are natural features we value and seek to conserve.

In respect of geoconservation and geodiversity, the most important natural process systems active in Tasmania today are fluvial (running water), karst, coastal (including coastal aeolian) and soil processes. Inland aeolian and periglacial processes are currently minor in the Statewide context, and occur in localised areas. These key processes are fundamental in the formation, maintenance, and development of Tasmania's geodiversity.

The geoconservation values can be degraded by human activities that either change the significant and valuable features of a site, or change the natural processes controlling the continuing development of the feature. Landforms composed of unconsolidated sediments are particularly vulnerable (Internal linkKiernan 2007). Geological and landform features are typically fossil or develop so slowly that degradation is permanent and destruction, or extinction, of an important site can occur from a single event such as excavation or the passing of one bulldozer blade, the removal of specimens or poor land management practices. For instance, many important geological and landform features are of small scale and may easily be destroyed by land development or resource extraction activities. Other landform systems such as karst and fluvial systems are dependent on balanced physical and chemical conditions and they can be significantly damaged if changes occur in their surrounding environment.

Some examples of geological and landform features in Tasmania that have been lost or damaged include the following:

  • The loss of key Tertiary and Quaternary fossil sites destroyed or inundated around the State (estimated at representing approximately 50% of the significant sites identified in the last 100 years). Fossil sites that remain intact include the Tertiary fossil bluffs and Quaternary megafauna bone deposits found in cave systems.
  • Impacts on significant geological sites in road cuttings such as the removal of a Precambrian folding near Somerset by excavation due to road realignment.
  • Collection for research resulting in the removal of valuable or rare fossil stumps and Thylacine subfossils from caves.
  • The collection of rare or significant minerals (particularly on the west coast).
  • Only a few of the 120 deflation hollows and 70 associated lunette features have been left in an undisturbed condition.
  • Inundation of the original Lake Pedder aeolian landform assemblage (by hydro-electric development).
  • Erosion of significant fluvial landforms on the Gordon River (by hydro-electric development and the wake from tourist cruise boats).
  • Removal of a terminal moraine marking a maximum glacial ice advance in the Mersey Valley (by quarrying activities).
  • Damage to Exit Cave in the south of the State by limestone quarrying in part of the cave system (a magnesite tower karst was destroyed in the mid-1980s).
  • Degradation of thermal spring mounds and associated swamps in the Smithton area (by agricultural and residential developments).
  • Infestation of coastal dunes by marram grass (Ammophila arenaria) and other weed species that have altered natural coastal processes and removed mobile sand from affected systems. For example, extensive plantings of marram grass on seaward dunes located in the Waterhouse area in the north-east of the State has caused erosion to downwind dunes.
  • Erosion of dunes and Aboriginal middens in the Arthur–Pieman rivers area (through off-road vehicle use and cattle grazing).
  • Loss of organic blanket bogs in western Tasmania (due to wildfires and inappropriate management burns) (see, for example, Internal linkPemberton 2007; Internal linkSharples 2002; Internal linkDixon 1997).

Tertiary fossil bluff

Tertiary fossil bluff in northwest Tasmaniainternal SOE link to larger image

Quaternary megafauna

Quaternary megafauna cave fossils in northwest Tasmaniainternal SOE link to larger image

Cave crickets

Cave cricketsinternal SOE link to larger image

It is impossible to produce a comprehensive list of all the potential pressures and threats to geoconservation values. Numerous human activities can impact on these values, and the variety of types and vulnerabilities of Earth phenomena means that an activity may have detrimental effects on some Earth features while others are robust and essentially impervious to the pressure. The embedded Internal linktable summarises some conservation concerns about significant Earth features and processes. These examples are illustrative and do not present an exhaustive list.

In addition, climate change and sea-level rise are likely to have major effects on geodiversity in Tasmania. However, the nature and intensity of these effects are poorly understood at present. A CSIRO and Bureau of Meteorology report predicts that by 2010–40, exceptionally hot years might affect about 75% of the State, and occur every 1.3 years on average; that by 2010–40, exceptionally low rainfall years might affect about 10% of the State and occur about once every 12 years on average; and by 2030, exceptionally low soil moisture years might affect about 11% of the State and occur about once every 9 years on average (see Internal linkHennessy et al. 2008). More information on climate change is provided in the embedded document Internal linkClimate Change in Tasmania. Additional information on climate variability, climate change and habitat change in Tasmania can be found in the Internal linkClimate Variability and Change (Air) Issue Report, Internal linkClimate Change and Natural Values (Natural Values) Issue Report and Internal linkHabitat Change Issue Report.

Geotourism

Geotourism is an area which has received little attention in Tasmania. In many parts of the world, geotourism is seen both as a way of making geoconservation 'pay for itself', as well as being a means of justifying expenditure on geoconservation initiatives (Internal linkSharples 2004). Much of the tourism in the State is classified as 'ecotourism' and based on promotion of our relatively undisturbed natural environment. For example, the natural landscapes of the Tasmanian Wilderness World Heritage Area (TWWHA) are one of the key drawcards for tourism. Ecotourism is a significant sector of the Tasmanian economy. In 1989, the International Union for the Conservation of Nature (IUCN) recognised the contribution of geodiversity values in the TWWHA to three of the four natural values criteria for nomination. Some sites recognised as being of outstanding universal value in the TWWHA include:

  • Collingwood River white schist – eclogite association
  • Mt Anne (north-east ridge) glaciokarst
  • Lake Pedder outwash basin (the natural system prior to flooding inundation)
  • New and Salisbury River basins fluvial and karst process systems
  • Weld River basin undisturbed karst process system
  • Macquarie Graben tectonically influenced peatland fluvial system
  • Lower Gordon levee hosted meromictic lakes
  • Central Plateau glacial terrain
  • Cynthia Bay Thule–Baffin moraines

Assessing and measuring the current situation

Geoconservation in Tasmania focuses on developing a comprehensive, adequate and representative (CAR) approach to the conservation and management of geodiversity. Land managers aim to target the best (or most outstanding) examples of natural geological, geomorphological and pedological features, assemblage of features, or processes and systems.

In the last five years since the 2003 SoE Report, the most significant improvements in the capacity to monitor and assess the condition of geodiversity in Tasmania have related to karst and fluvial process integrity. There has also been far greater attention to the coastal zone due to growing community concern about the importance of coastal geomorphology in coastal vulnerability to sea-level change. There are few dedicated programs directed towards monitoring changes in the condition of Tasmania's geodiversity, although programs such as the Conservation of Freshwater Ecosystem Values (CFEV), Tasmania River Condition Index (TRCI) and Monitoring Vegetation Extent Program (MVEP), along with fluvial systems and coastal geomorphic mapping can help to inform an assessment of some components of geoconservation condition.

Geodiversity indicators

Geoconservation focuses on identifying and classifying the range of geological, geomorphic and soil phenomena. Indicators in this SoE Report provide measures of our knowledge about the different elements of geodiversity in Tasmania. The following three broad categories of geoconservation indicators that were proposed in the previous SoE reports remain relevant (Internal linkSharples 2001). However, none of these indicators in this SoE Report provide a comprehensive assessment of geodiversity or the condition of geological features or geomorphological processes. There appears to be a continuing need to assess geo-programs that contribute to our understanding about geodiversity in terms of their capacity to inform geoconservation issues.

  • Data coverage indicators: the status of knowledge about geodiversity, that helps to ensure the successful conservation of these natural values.
     
  • Site integrity indicators: the degree of physical integrity or degradation of sites and features that are identified broadly in the Tasmanian Geoconservation Database (TGD) as being sites of geoconservation significance.
     
  • Process integrity indicators: the degree of integrity or degradation of geomorphic and soil processes. These indicators govern the long-term integrity of sites, features and systems of geoconservation significance, and the integrity of ecosystem processes generally.
     

The most critical themes for geoconservation assessment and management in Tasmania have been assessed as fluvial, karst, coastal and soil issues. This is because they involve the maintenance of ongoing natural processes in the ecosystem and are pervasive natural values in the landscape. Fossil geoheritage features (e.g. bedrock features, relict landforms) are also locally important at the sites where significant features occur, but are less pervasive across the landscape.

Data Coverage

Our ability to identify or locate representative (or outstanding) examples of each significant element of geodiversity depends on mapping and research on geological, geomorphic and soil features and systems. Our capacity to identify, assess and monitor representative examples of Tasmania's diverse geodiversity also governs our ability to know whether the State's geodiversity is being conserved and appropriately managed (and thus our ability to identify geoconservation issues and priorities requiring action). Relevant data coverages and their approximate data availability status are identified in the table below.

Data coverage of geoconservation mapping and inventories

Potential indicator Data available Comments
Geological (bedrock) mapping Good Statewide Coverages available at different scales
Geomorphic mapping and research Limited
Soil mapping Limited Partial coverage of State (inconsistencies in coverages)
Tasmanian Geoconservation Database (TGD) Partial Statewide coverage
Reconnaissance geoconservation inventories Some data available
Systematic thematic geoconservation inventories utilising geodiversity classifications Some data available
Detailed geoconservation: oriented inventories or studies of geomorphic or soil systems for fluvial, karst, coastal, and soils Some data available
Process monitoring sites for geomorphic or soil systems (total number of sites and distribution with respect to georegions) for fluvial, karst, coastal, and soils Some data available

Source: DPIW 2008


Geological mapping and research in Tasmania has traditionally been biased toward areas considered likely to be prospective for economic mineral deposits (or problems of slope and stability in urban environments). This bias was more pronounced in the 1980s and 1990s with the coverage of geological mapping, particularly the 1:25,000 map series, reflecting the emphasis on mineral deposits. Areas of eastern and southern Tasmania that are perceived as relatively unprospective have only been mapped at a 1:250,000 reconnaissance scale.

The varying degree of geological mapping has consequences for geoconservation and geological heritage inventories, in that there is greater awareness of significant geological phenomena for the areas that have been mapped (and therefore studied) in more detail. The current status of geological mapping coverage of Tasmania is presented in the embedded Internal linktable.

Current soil mapping for Tasmania comprise reconnaissance soil maps that cover some of the agricultural areas and a few of the designated reserves. Much of the reconnaissance soil mapping was undertaken by CSIRO in the 1940–60s (originally published at 1:63,360 scale). These small- and large-scale soil survey maps and reports form the basis of our current knowledge and understanding of the distribution and types of soils (as a component of geodiversity) within the State. Soil maps have been developed using the CSIRO reconnaissance soil mapping as a base for the majority of agricultural areas in the State and they are covered by the updated reconnaissance 1:100,000 soil maps series. However, there remain many areas of Tasmania, including highly productive agricultural areas, where no soil maps exist. Overall, mapping of soils is best known in the more disturbed areas (i.e. agricultural land, private land, State Forest), and less well known in more undisturbed areas (i.e. national parks, reserves). More information on the updated reconnaissance soil maps series can be found though the Internal linkSoil Diversity Issue Report, Internal linkDistribution of Soils Indicator and the DPIPWE External linkSoil Maps of Tasmania website.

The TGD is the over-arching inventory for geodiversity in Tasmania. The database is maintained by DPIPWE. The purpose of the TGD is to record all sites and areas in the State that have been recognised as having significant geoconservation value by inventory processes. The TGD was initiated in 1996 during the Tasmania-National Regional Forest Agreement (RFA) process by amalgamating records from all Tasmanian reconnaissance-level inventories that were available (Internal linkDixon and Duhig 1996). At the time, the TGD was developed in a forestry context although it was recognised that the database had a wider application and DPIPWE assumed responsibility for its management in 1999 (Internal linkEberhard 2008).

Sites listed on the TGD v.6.0 (2008) occupy an area of 4,104,842 ha, of which 3,206,805 ha (78%) is reserved land. The database is subject to ongoing annual review and upgrading by an expert reference group comprising geoscientists from government, industry and the University of Tasmania. On the advice of the expert reference group, 48 new sites were listed, 19 sites delisted and improvements were made during the period 2003–07 (Rolan Eberhard pers. comm. 2009).

The TGD has no statutory basis, but is widely used as a planning tool by government and non-government agencies. The database is referred to in the State Codes of Practice: Mineral Exploration Code of Practice 1999, Reserve Management Code of Practice 2003 and Forest Practices Code 2000. In addition, some reserves established under Tasmanian Government programs such as the Community Forest Agreement (CFA), Private Forest Reserves Program (PFRP) and Protected Areas on Private Land (PAPL) have been selected with reference to geoconservation criteria. However, many other reserves established under these programs have not been selected with reference to geoconservation criteria. Geological, geomorphological and soil values have yet to be systematically assessed for these reserves.

One recent example of a site listed on the TGD is the Egg Islands near Huonville. Covering 440 ha, the two islands are listed in the TGD as a representative geomorphological feature (tidal delta islands) of State significance. They comprise a mix of marshlands, forests and wetlands that are partly privately owned and partly managed by the Parks and Wildlife Service (PWS) as a conservation area. The Tasmanian Land Conservancy (TLC) purchased the privately owned portion of the islands in 2008 and this non-government organisation continues to work closely with the National Reserve System (NRS) Program to protect other sites of geoconservation significance and add them to the reserve system (Internal linkTLC 2008).

Statewide coverage of differing major types of fluvial, karst and coastal landforms, including the mapping of their spatial distribution at a uniform scale, is available or in preparation. However, detailed Statewide mapping has yet to be completed for other geoconservation themes.

Site integrity

Site integrity refers, for example, to the maintenance of the significant contents or exposures of a bedrock site, the maintenance of the forms of significant landforms, or the maintenance of the profiles and coverage of soils at significant representative soil sites. Note that it is possible to have sites, such as the flooded Lake Pedder, whose forms and contents remain intact (i.e. site integrity is high), although their natural processes no longer function naturally (i.e. process integrity is currently low).

The TGD provides useful information on geoheritage site integrity, with data on the condition (degradation) and conservation status of geodiversity in Tasmania. The site condition indicators detailed in the Internal linkSite Condition of Identified Sites of Geoconservation Significance Indicator below are derived from information recorded on the TGD. The condition indicator (TGD field = Degradation Class) is a qualitative measure of the condition (integrity) of the geoconservation values of a site, based on:

  • degree of anthropogenic disturbance to the form and fabric of geological, geomorphological and/or pedological features;
  • degree of anthropogenic disturbance to natural processes that contribute to the ongoing evolution of geological, geomorphological and/or pedological features; and
  • clarity of exposure (geological exposure sites only).

At present, there is no process for systematically reviewing or updating the site condition or conservation status of TGD sites, many of which were listed in the mid–1990s. Changes in the percentage representation of geological, geomorphological and soil attributes in the different degradation and conservation status classes are therefore primarily attributable to new TGD listings, not actual changes in condition status. Therefore, the information presented in this SoE Report only provides a general overview on condition and conservation status.

Process integrity

Process integrity refers to the maintenance of the relevant natural processes operating at, or upon, a site or system of geoconservation value. For example, process integrity refers to the maintenance of the hydrological or other processes which operate in a natural landform or soil system, and which govern the rates and magnitudes of natural change in such systems. In general, process integrity is less relevant to bedrock features or relict landform assemblages rather than to contemporary landform and soil systems whose integrity and continuing evolution is governed by ongoing natural processes. However, understanding how process integrity affects geodiversity is important because it assists in reporting on landscape-scale changes in the environment.

Although the TGD contains some information relevant to process integrity, the data is directed towards assessments of site integrity. Instead, an assessment of process integrity is built into an analysis of a base map (identifying the spatial distribution of the major types or elements within a given geodiversity theme such as fluvial, karst or coastal landform systems), and overlain by appropriate layers that identify the differing condition or conservation status of the theme (i.e. the degree of naturalness or artificially induced change for the types or elements within the theme). In effect, a base map depicting the spatial distribution of differing elements of geodiversity is the essential component that makes the difference between a specialised indicator of the state of geodiversity, and a more generalised environmental indicator.

The Fluvial Systems Project developed a method for defining geomorphic river regions at a Statewide scale (Internal linkJerie et al. 2003). Aspects within the environment that influence river development, character and form defined the geomorphic river regions. These aspects broadly included lithology, climate, geomorphic process history, topography, vegetation and geological processes. Environmental Domain Analysis (EDA) was used as a foundation to produce 90 regions or 'fluvial mosaics' across the State that were found by the analysis to be internally consistent in relation to the environmental controls on river development. The EDA resulted in a map that included 489 different river environment domains, many of which occurred in multiple patches (where a patch is an area that is internally consistent in terms of the system controls on river development and a domain is composed of one or more similar patches). In total, 129 thousand patches of river landscape were identified in the State. This information has been used to characterise rivers from which river styles mapping is being developed to identify catchment characters, fluvial landforms and mosaics, and reference reaches for key fluvial mosaics. The information is being used as a tool to link geo-river conservation priorities with sustainable water management and use. Data from this project has contributed to the CFEV Project and been incorporated into TRCI. More information on the geomorphic landscape mosaics and river regions can be found in the Internal linkRiver Naturalness Indicator.

The CFEV Project has developed a framework for the management, development and conservation of freshwater-dependent ecosystem values in Tasmania based on CAR reserve-design principles. Key products of the project have been an assessment framework and the CFEV database. The database is an information tool that provides environmental data relating to freshwater areas (including groundwater and karst) of low to high conservation management priority (Internal linkDPIW 2008). CFEV data is intended to be a baseline for TRCI. More information on the high conservation value of freshwater ecosystems and the CFEV program can be found though the Internal linkRiver Naturalness Indicator, Internal linkExtent and Condition of Riparian Vegetation Indicator and Internal linkExtent and Condition of Wetlands Indicator, and the DPIPWE External linkThe Conservation of Freshwater Ecosystem Values Program website.

TRCI was established by DPIW (now DPIPWE) to provide a rapid assessment approach to evaluate river health from a total ecosystem perspective (see Internal linkNRM South 2008). TRCI currently assesses five key components of rivers: aquatic life; hydrology; water quality; physical form (geomorphology); and the streamside (riparian) zone. The index has been designed to measure the condition of the whole river ecosystem and will initially monitor the condition of river systems relative to a reference state. The data will contribute to the understanding and management of the physical, chemical and ecological processes that drive river condition, including the provision of a uniform approach to identify geodiversity values and geoconservation threats. More information about TRCI and the rapid assessment of river condition can be found through the DPIPWE External linkIndex of River Condition website.

A base map for the indicators of the state of karst geodiversity in Tasmania exists in the form of an atlas of Tasmanian karst (Internal linkKiernan 1995). The most recent version of the digital Tasmanian Karst Atlas is v.3.0 (2003) is held by DPIPWE and includes all known karst areas in the State (Internal linkSharples 2003). The map does not identify individual karst features such as caves, but maps each discrete area of karstic or potentially karstic carbonate bedrock (initially considered by Internal linkKiernan 1995). According to the karst layer comprising carbonate units and strata containing carbonate units, at 2007, karstic and potentially karstic carbonate rocks occupied approximately 419,012 ha. The actual presence of karst is yet to be confirmed in some cases (Internal linkDPIPWE 2008). Approximately 222,567 ha (53% of the total) was protected in formal and informal reserves on Crown and private land.

It is difficult to report upon known pollution of karst aquifers in Tasmania because there is a paucity of quantitative data on water quality in Tasmanian karst areas. These areas are subject to a spectrum of land use practices, some of which have been identified as actual or potential sources of pollution to karst aquifers (e.g. quarrying, forestry, agriculture, urban development and landfill). The historically widespread practice of using sinkholes and caves for disposing of domestic and agricultural waste in some northern rural karst areas is a potentially significant, but little publicised, threat to groundwater quality (see, for example, Internal linkBenjamin 2008). Further work is required to assess the environmental effects of waste disposal and other practices that impact karst areas. In addition, because of the potential role of karst aquifers in providing long-term indicator sites for surrounding catchment condition, there is scope for including some selected karst sites in the DPIPWE Statewide Baseline Water Quality Monitoring Program (BWQMP).

In order to create an endorsed methodology to monitor and map changes in vegetation extent over time, DPIW (now DPIPWE) commenced the MVEP in 2005. The project compares Statewide Landsat satellite images across a five-year period to detect forest cover changes, which are then verified using information from other sources such as Forest Practices Plans and high-resolution imagery. The mapped changes will be used to update TASVEG and to create a baseline for future monitoring.

Coastal geomorphic mapping has been extended since the 2003 SoE Report and the relevant digital maps updated (Internal linkSharples 2006). These maps comprise the Tasmanian Shoreline Geomorphic Types Digital Line Map v.4.0 (2006) and the Tasmanian Quaternary Coastal Sediments Digital Polygon Map v.4.0 (2006). Shoreline types have been classified using criteria based on sensitivity to erosion in response to sea-level rise and climate change.

In 2007, researchers at the University of Tasmania commenced work on a national project for the Australian Greenhouse Office and Geoscience Australia to produce a line-format geomorphic map of the Australian coastline using a nationally-consistent landform classification system. This national approach has been largely modelled on the approach developed in Tasmania. The national map will be useful for assessing coastal vulnerability to sea-level rise and a range of other applications including input into the national Oil Spill Response Atlas (Internal linkSharples 2007).

The coastal georegion classification attempts to classify the 'overarching controls' that will influence the development of coastal landform types occurring in a coastal georegion. For example, the coastal georegion classification does not provide information on whether sandy beaches will occur in a particular coastal segment, but identifies that if they occur, they will tend to be of a certain type distinct from sandy beaches in other georegions. Therefore, any particular coastal georegion will contain a suite of differing landforms. However, the suite of landforms will be of types distinct from the landforms that have developed in other coastal georegions.

An alternative classification of coastal types is the Integrated Marine and Coastal Regionalisation of Australia (IMCRA v.4.0, 2006). More information on this classification can be found on the Department of Environment, Water, Heritage and the Arts (DEWHA) External linkIntegrated Marine and Coastal Regionalisation website. IMCRA is a classification of broad marine and coastal ecosystem types include geological and geomorphic character, and was developed to facilitate assessment of marine and coastal biodiversity conservation requirements (Internal linkDEH 2006). The latest version of IMCRA combines IMCRA v.3.3 (which provided a marine regionalisation of inshore waters) with the National Marine Bioregionalisation (which extends regionalisations beyond the continental shelf to cover all of Australia's Exclusive Economic Zone) (Internal linkDEWHA 2008). The coarse scale of the IMCRA regions, and the very broad classifications of geodiversity that are used in the framework, means that their use as a base dataset for the development of indicators to report on the state of coastal geodiversity in Tasmania would provide only very broad and generalised indicators when compared to using the more detailed coastal georegions mapping described above. Nonetheless, IMCRA may provide useful information when applied in combination with other types of conservation indicators.

The following indicators summarise the current state of knowledge that contributes to our understanding of geodiversity in Tasmania.

Indicator introduction

Environmental indicators help track changes in the environment. Indicators can help in gaining an appreciation of conditions and trends and changes in the environment without having to capture the full complexity of the system, which is typically unknowable for most ecosystems: it is inherently complex and always changing, as is human interaction with the environment.

Indicators may be physical, chemical, biological or socio-economic that provide useful information about the whole system. In SoE reporting, indicators are also often classified as to whether they relate to the condition of the environment, pressures caused by people on the environment or management responses (in seeking to reduce pressure and improve condition).

In the 2009 SoE website, an indicator may be used across more than one issue report or chapter. For example, measures of water quality in Tasmania's rivers and streams tell us about the condition of these aquatic systems and are used in this part of the SoE Report (condition of freshwater). They may also tell us about pressures on estuaries receiving water from these rivers and catchments (pressures on estuaries).

Index of geoheritage indicators

Condition indicators Pressure indicators Response indicators
Indicator Indicator description
Site Condition of Identified Sites of Geoconservation Significance The percentage of sites on the Tasmanian Geoconservation Database that are in each condition (degradation) class
Site Conservation Status of Identified Sites of Geonconservation Significance The percentage of sites on the Tasmanian Geoconservation Database (TGD) that are in each conservation status class
Land Cover Modification by Area of Karst Type This indicator details exposed, covered, interstratal karst areas across the State along with karst catchment areas
River Naturalness Naturalness ranking (integrated biophysical condition) for each river section from the CFEV Project presented as total length across the state and per catchment
Extent of Forest and Non-Forest Vegetation Area and reservation status of forest and non-forest vegetation communities in total and by bioregion
Extent and Condition of Riparian Vegetation The area and condition of native riparian vegetation by type
Sea Level Change Tasmanian regional implications of data from the National Tidal Centre (NTC), including the high accuracy SEAFRAME (SEA-level Fine Resolution Acoustic Measuring Equipment) sites
Artificially Modified Coastlines The distribution of substantially or wholly artificial shorelines around the Tasmanian coastline
Vulnerability of Coastal Geodiversity The vulnerability of various shoreline geodiversity types to erosion and recession caused by wave action and other hazards such as sea-level rise and storm surge flooding
Native Vegetation Clearing Rate of clearing, in hectares per annum, of terrestrial native vegetation types, by clearing activity
Weeds of Significance Present in Tasmania Distribution of marram grass (Ammophila arenarias) and rice grass (Spartina anglica) in Tasmania
Density of Road Networks and Walking Tracks The density of roading and walking tracks in a region (e.g. catchments)
Potential Area Affected by Erosion The area of land affected by or prone to water erosion
Geoheritage Protection The extent of karst conserved within the comprehensive, adequate and representative (CAR) Reserve System and under the Community Forest Agreement (CFA)

Indicators

Geonconservation condition

Condition of identified sites of geonconservation significanceinternal SOE link to larger image



Site Condition of Identified Sites of Geoconservation Significance - at a glance

The condition of geoconservation sites listed in the TGD in 2008 is presented in this indicator. Measuring the condition (degradation) of sites listed as having geoconservation significance in the TGD, and the changes in the number of sites in each condition class over time, indicates the level of site degradation and the changes in geoconservation practice in Tasmania.

  • There were 1038 sites listed in the TGD in 2008.
     
  • Of the geological sites of geoconservation significance listed on the TGD, 24.7% have experienced no dedgradation, 10.5% have undergone some level of degradation and 64.5% are unknown, out of a total of 885 listed sites.
     
  • Of the geomorphological sites of geoconservation significance listed on the TGD, 33.5% have experienced no degradation, 22.9% have undergone some level of degradation, and 39.5% are unknown, out of a total of 830 sites.
     
  • Of the soil sites of geoconservation significance listed on the TGD, 25.3% have experienced no degradation, 37.4% have undergone some level of degradation, and 37.3% are unknown, out of a total of 75 sites.
     

Geoconservation status

Conservation status of identified sites of geonconservation significanceinternal SOE link to larger image



Site Conservation Status of Identified Sites of Geonconservation Significance - at a glance

The conservation status of geoconservation sites listed in the TGD in 2008 is presented in this indicator. It is important to understand the degree to which current tenure and land management regimes are likely to protect or degrade the geoconservation values of a site. This parameter forms a more meaningful indicator of geoconservation significance than would land tenure alone, since some geological features are more robust than others, and not all significant geological features require conservation land tenure protection for their values to be adequately maintained.

  • There were 36 internationally listed sites and 119 nationally listed sites of geoconservation significance in the TGD in 2008.
     
  • Of the geological sites of geoconservation significance listed on the TGD, 24.4% are secure, 24.6% are either endangered, threatened or have a potential threat, 0.3% have been destroyed and 50.6% are unknown, out of a total of 885 listed sites.
     
  • Of the geomorphological sites of geoconservation significance listed on the TGD, 26.1% are secure, 32.4% are either endangered, threatened or have a potential threat, none have been recorded as destroyed, and 38.6% are unknown, out of a total of 830 sites.
     
  • Of the soil sites of geoconservation significance listed on the TGD, 28% are secure, 53.4% are either endangered, threatened or have a potential threat, none have been recorded as destroyed, and 18.7% are unknown, out of a total of 75 sites.
     

International significance

Geodiversity sites of international significanceinternal SOE link to larger image

National significance

Geodiversity sites of national significanceinternal SOE link to larger image

Karst in Tasmania

Areas of exposed, covered or interstratal karst in Tasmaniainternal SOE link to larger image

Karst in northern Tasmania

Areas of exposed, covered or interstratal karst in northern Tasmaniainternal SOE link to larger image



Land Cover Modification by Area of Karst Type - at a glance

This indicator details exposed, covered, interstratal karst areas across the State along with karst catchment areas. It also provides a list of key karst sites in Tasmania sourced from the TGD in 2008 and describes karst types according to percentage area under the modified land cover classes. It classifies karst types with &gt;30% modified land cover, 20–30% modified land cover, and <20% modified land cover. The following analysis is subject to the data availability and limitations detailed within the indicator.

Data is included on plantation development that presently occurs over karst areas in the State and information on karst areas with respect to the development, conservation and management of the State's water resources. Given that karst is often found across the landscape rather than being confined to individual properties or by land tenure boundaries, it is important to take catchment areas, drainage patterns and land clearance into consideration when assessing the condition of karst systems (Internal linkBenjamin 2008). It is also necessary to take into account human-induced activities such as waste disposal or the application of fertilizers and pesticides.

  • Some 300 areas are likely to have karst bedrock, underlying about 400,000 ha or 6% of the State (Internal linkEberhard 2007; see also Internal linkForestry Tasmania 2002).
     
  • Tasmania's best developed karst and the majority of caves occur in carbonate rock formations of intensely karstified or probably intensively karstified land (Category A) that are mostly Ordovician limestones and Precambrian dolomites (approximately 31% of all carbonate rocks in the State). Some substantially karstified or probably substantially karstified areas (Category B) are known to be cavernous at some sites, although the karst may be under-developed and is yet to be confirmed in some instances (approximately 42% of carbonate rocks). The partially and possibly karstified karst areas (Categories C and D) contribute approximately 6% and 20% of formations respectively (Internal linkEberhard 2007).
     
  • Karst sites listed on the TGD total an area of approximately 228,000 ha and they encompass considerable diversity in the scale and types of features and systems (Internal linkEberhard 2008). Despite the inclusion of many karst areas and sites on the TGD, some gaps have been identified.
     
  • Land cover modification on karst alters the hydrological processes and flow regimes, and therefore affects karst processes. The pollution of karst aquifers is also more likely to result from areas of land cover modification, particularly in urban and suburban areas.
     
  • Areas of Silurian-Devonian limestone karst lithology have <20% modified land cover and they have experienced the least land cover modification (approximately 6% of 30,700 ha total area).
     
  • Karst types that have experienced the greatest land cover modification (>30%) are the Tertiary marine limestones (74% of 15,600 ha), Quaternary limestones (69% of 29,000 ha) and Permian limestones (44% of 21,700 ha).
     
  • Karst in urban areas has also been modified. Ordovician limestone has experienced the greatest land cover modification (900 ha) followed by Precambrian–Cambrian lithology (530 ha).
     
  • Plantation development presently occurs on only isolated areas of mapped karst in Tasmania. Ordovician limestone has the largest combined area of plantation cultivation with approximately 4,000 ha, covering around 3% of this karst type. Permian limestones contain the greatest area of plantation as a proportion of total karst area, with approximately 5% coverage (1,070 ha). Plantation development is a potential issue for management of karst in some parts of Tasmania. Karst systems rely on the maintenance of hydrologic and geomorphic processes, which depend on water availability and water quality (Internal linkPFT 2007; Internal linkSharples 2003).
     
  • Approximately 46% of the total karst areas in the State have not been affected by abstraction or diversion, a further 45% have experienced only minimal abstraction and 3% minimal diversion. Karst areas most affected by diversion include Montagu River 2 and Tin Spur Creek, and those most affected by abstraction include Grassy, Mole Creek 2, Calvert Hill, Rough Hills, Dismal Swamp, Wilmot River and Scotts Peak (Internal linkCFEV database, v1.0 2005).
     
  • Karst areas in Tasmania have also remained relatively free from regulation (92% of 334 karst areas and 95% of 410,395 ha total karst area). A scattering of karst areas across the State (approximately 4% of the total) have experienced a high amount of regulation with one of the worst areas being Sugarloaf Spur in the Macquarie Catchment (Internal linkCFEV database, v1.0 2005).
     

River naturalness score (CFEV)

River naturalness score (CFEV)internal SOE link to larger image

Geomorphology domain mosaic

Geomorphology domain mosaicinternal SOE link to larger image

Geomorphic river types

Geomorphic river typesinternal SOE link to larger image



River Naturalness - at a glance

This indicator includes river naturalness and fluvial systems mapping. It illustrates some key examples of river styles mapping that are being developed as part of the DPIPWE Fluvial Systems Project in partnership with the NRM regions and Greening Australia. Fluvial mapping aims to identify catchment characters, fluvial landforms and mosaics, and reference reaches for key fluvial mosaics that illustrate geo-river naturalness (see Internal linkJerie et al. 2003). The results of this project have been incorporated into the CFEV Project.

A naturalness assessment of rivers in the Tasmanian river network has been incorporated into the CFEV dataset. 'Naturalness', as defined under the CFEV Project, can be used as an overall index of river condition (Internal linkDPIW 2008). The CFEV assessment indicated that the river network across Tasmania extends 152,941 km. It also identified that a further 4,082 km of artificial pipeline and linking sections within waterbodies extend across certain parts of Tasmania. Artificial pipelines and linking sections were not assessed for condition.

  • Ninety regions or 'fluvial mosaics' that were mapped across the State were found by the EDA analysis to be internally consistent in relation to the environmental controls on river development. As part of this analysis, 489 different river environment domains and 129 thousand patches of river landscape have been identified.
     
  • Geoomorphic 'fluvial aspects' have been monitored by DPIPWE, in partnership with NRM regions and Greening Australia, and reference condition sites have been determined for a number of river reaches across the State. The 10 most abundant river types are detailed in this indicator.
     
  • More detailed 'fluvial mapping' that has been piloted for the Leven, St Patrick and Coal rivers. River types and geomorphic types in the Leven River Catchment are included in this indicator.
     
  • The CFEV naturalness assessment found 114,175 km (75%) of the State's river length to be in near natural condition and 24,478 km (16%) to be severely altered from their natural condition.
     
  • An assessment of river naturalness across the 48 Land and Water Management Catchments in the State found that catchments retaining >80% of their total river length in a near natural condition included the George (81.2%), Huon (86.7%), Swan–Apsley (87.1%), Pieman (88.1%), King–Henty (88.7%), Scamander–Douglas (88.9%), Arthur (90.8%), Gordon–Franklin (95.7%), Nelson Bay (98.6%), Port Davey (99.4%) and Wanderer–Giblin (99.5%) catchments.
     
  • The Brumbys–Lake (61.4%) and Meander (60.3%) catchments had >60% of their total river length severely altered from their natural condition. Other catchments with lower fluvial system integrity include the Jordan, Pittwater–Coal and King Island catchments.
     

Leven River catchment

Geomorphic mosaic and river types for the Leven River catchmentinternal SOE link to larger image

Woody vegetation change, ~1994–2001

Woody vegetation change, ~1994–2001internal SOE link to larger image

Forest vegetation change, 2000–05

Components of forest vegetation change, Statewide vegetation change 2000–05internal SOE link to larger image

Non-forest vegetation change, 2000–05

Components of non-forest vegetation change, Statewide vegetation change program 2000–05internal SOE link to larger image

Cleared land within the coastal zone

Cleared land within the coastal zoneinternal SOE link to larger image

Coastal vegetation change, 2000–2005

Coastal vegetation change, 2000–2005internal SOE link to larger image



Extent of Forest and Non-Forest Vegetation - at a glance

This indicator reports on the area remaining and distribution of native forest and non-forest vegetation at the Statewide level. As well the extent of native vegetation communities being the best available measure of ecosystem diversity, it also provides an indication of pressure to karst, fluvial and coastal systems. This indicator draws on data from the TASVEG v.1.3 vegetation map (Internal linkDPIW 2007) and the summary of reservation status for TASVEG vegetation communities (Internal linkDPIW 2008). The Forest Practices Authority compiles data on the maintenance of the Permanent Forest Estate (Internal linkFPA 2007; Internal linkState of Tasmania 2007). Information on changes in the extent of native non-forest communities is available through the Monitoring Vegetation Extent Project (Internal linkTVMMP 2008).

Changes in vegetation cover, especially from deep-rooted to shallow-rooted vegetation types (or visa-versa), has a major effect on important geomorphic hydrological, soil and coastal processes including water runoff and infiltration rates, slope and karst drainage patterns and flow regimes, and soil erosion rates. Changes of vegetation cover to bare urbanised ground also significantly impacts geodiversity.

  • At the Statewide level, the largest percentage decreases in the Permanent Forest Estate across Tasmania occurred in the Woolnorth and Ben Lomond bioregions with decreases of 35,303 ha (9.4%) and 39,178 ha (7.8%) respectively in the period 1996–2007.
     
    • Native non-forest vegetation in the State covers about 1.5 million ha of which about 1.0 million ha (68%) of the total area is contained in secure reserves.
    • Of the 66 TASVEG non-forest vegetation communities, 14 communities have less than 30% area in secure reserves, including: lowland grassland complex (700 ha reserved or 1%); lowland Themeda grassland (209 ha reserved or 3%); and lowland Poa labillardierei grassland (485 ha reserved or 3%).
    • In the coastal zone, approximately 128,300 ha (14%) of land has been cleared and 794,600 ha (86%) has not been uncleared.
    • The Monitoring Vegetation Extent Project identified a decrease in the extent of native non-forest vegetation in the State of 3,807 ha from 2000–05. The non-forest communities for which the largest area decreases since 2001 were recorded were lowland grassland complex (1,185 ha decrease or 33% of the cleared total), coastal heathland (547 ha decrease or 15% of the cleared total), lowland Poa labillardierei grassland (396 ha or 11% of the cleared total), and scrub complex on King Island (358 ha or 10% of the cleared total). Lowland Poa labillardierei grassland decreased in total area by about 2% from its 2001 area of 17,700 ha. These vegetation groups were mostly converted to agricultural, urban and exotic vegetation.
     
  • Overall, there are 17 non-forest vegetation communities that are listed as threatened under the Nature Conservation Act 2002. Five threatened non-forest vegetation communities have less than 30% of their area contained within secure reserves Statewide. These vegetation communities are riparian scrub, Melaleuca pustulata scrub, heathland on Calcarenite, wetlands, and the coastal complex on King Island. All these vegetation communities are found in the coastal zone.
     

Rriparian zone (major streams)

Native vegetation occurring in the riparian zone major streams (= stream order 3, CFEVinternal SOE link to larger image



Extent and Condition of Riparian Vegetation - at a glance

This indicator describes the extent and condition of native riparian vegetation at the catchment and Statewide scales. Retention or loss of riparian vegetation has a major impact on geological and geomorphological (and biological) processes in watercourses, particularly when vegetation loss results in erosion. Consequently changes in riparian vegetation, together with catchment vegetation cover changes, are possibly the two most important pervasive influences on fluvial system integrity.

Data for this indicator draws from the CFEV Native Riparian Vegetation Index (Internal linkCFEV database, v1.0 2005) and TASVEG data on native vegetation communities (Internal linkTVMMP 2006). The indicator also draws on recent riparian surveys (Internal linkDaley 2003 and Internal linkDaley & Kirkpatrick 2004). The following analysis is subject to this data availability and limitations detailed within the indicator.

  • The condition of Tasmania's riparian vegetation varies around the State. All bioregions have stretches of remnant native riparian vegetation in excellent condition. These stretches are usually located in areas that are remote or in conservation areas or reserves, but are also found on private land.
     
  • The CFEV Native Riparian Vegetation Index identified that the majority of the State retained native riparian vegetation cover, although a significant proportion (approximately 14.3% total Statewide river length) of river sections had limited or no remnant native vegetation cover. These areas are mainly located throughout the agricultural and urban areas of Tasmania.
     
  • Several south-west catchments such as the Wanderer–Giblin and Port Davey have a relatively greater proportion of their total stream length (for major streams) in the highest category (very to extremely high proportion of native vegetation in the riparian zone). These catchments have high fluvial system integrity. On the east coast, the Scamandar–Douglas catchment also has relatively high fluvial system integrity given that is has a relatively high proportion of its total stream length in the highest category. Some catchments have lower fluvial system integrity given that they retain relatively less of their native riparian vegetation including the Jordan, Brumbys Lake, Pittwater–Coal, Meander and King Island catchments.
     
  • The area of TASVEG communities contained within a 50 m buffer of major streams (stream order greater than two) was identified from CFEV and TASVEG data. The largest area covered in the riparian zone was agricultural land, with a total of 61,460 ha or about 20% of the riparian zone.
     
  • In 1998, data on river disturbance related to human intervention was collected as part of the assessment for the RFA. The unpublished data from the project shows that 18% of Tasmania's riparian vegetation, assessed along the 39,000 km of the State's major watercourses, was in excellent condition. It also showed that moderate to substantial disturbance was evident along approximately 20,855 km of major streams and watercourses (River Disturbance Index, Wild Rivers Project, 1998). From these data, a conservative estimate of 1,668 km2 (53%) of a possible 3,120 km2 of the riparian vegetation along major water courses in Tasmania was categorised as moderately to substantially disturbed.
     
  • An assessment of riparian vegetation condition was conducted as part of the National Land and Water Resources Audit (NLWRA) in 2001 (Internal linkDunn 2002). A table is presented in the indicator that proposes an update to this assessment. The major changes proposed are in the Central Highlands condition from 'good' to 'fair' and in the Central Highlands trend from 'static' to 'declining'. The condition of riparian vegetation in the King Bioregion is suggested to change from 'good' to 'fair' and riparian vegetation in the south-east changes from 'good' to 'fair' condition. The proposed changes are based on declining streamflows and lake levels affecting riparian vegetation.
     
  • In assessments conducted in 2003 and 2004, native riparian vegetation was regarded as relatively intact if exotic (weed) plants constituted less than 20% of the estimated overlapping cover and the stream showed no obvious signs of physical modification in the immediate vicinity. No stands of native riparian vegetation that met the selection criteria could be found in 44 of the grids that were easily accessed (see Internal linkDaley 2003; Internal linkDaley & Kirkpatrick 2004).
     

Key tide gauge stations in Tasmania

Key tide gauge stations in Tasmaniainternal SOE link to larger image

Distribution of relative sea-level trend

Distribution of relative sea-level trendinternal SOE link to larger image

Historical sea-level

Global historical sea-level reconstruction from 1842 projecting to 2100internal SOE link to larger image

TAR and AR4 projections

Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR) and the Fourth Assessment Report (AR4) projections of sea-level riseinternal SOE link to larger image



Sea-level Change - at a glance

This indicator reports on Tasmanian regional implications of data from the National Tidal Centre (NTC) in South Australia, which calculates annual sea-level trends at 35 longer-term sites (>25 years) under the Australian Baseline Sea Level Monitoring Project (ABSLMP) and 16 high accuracy SEAFRAME (SEA-level Fine Resolution Acoustic Measuring Equipment) sites around Australia. Other key references used for this indicator are the Indicative Mapping of Tasmanian Coastal Vulnerability to Climate Change and Sea Level Rise (Internal linkSharples 2006); Historical and Projected Sea-level Extremes for Hobart and Burnie, Tasmania (Internal linkHunter 2008); and the DPIW (now DPIPWE) policy report titled: Sea-Level Extremes in Tasmania: Summary and Practical Guide for Planners and Managers (Internal linkDPIW 2008).

Tasmania is being affected by changes in climate. These changes are leading to a wide range of environmental impacts, including a rise in the level of the seas that has been occurring at a sustained rate, which has not been experienced for at least 5,000 years (see Internal linkHunter 2007). Rises in sea-level is currently being felt along some of the State's coastline through an increased frequency of storm surges and coastal flooding events, coastal erosion and substantial changes to the bathymetry and topography of soft coastal margins (e.g. sandy shorelines). Sea-level rise and associated climatic changes will have long-term geomorphic impacts on coastlines around Tasmania, particularly along exposed low gradient sandy coasts. These impacts include:

  • increased salinity of rivers, bays and coastal aquifers;
  • increased shoreline recession and coastal erosion, particularly along exposed low gradient sandy coasts (i.e. a rough 'rule of thumb' of the Bruun Rule, is that for every 1 m of sea-level rise there will be 50–100 m of horizontal erosion of exposed sandy beaches, as outlined by Internal linkSharples 2006); and
  • loss of salt marshes, wetlands and intertidal sand flats.

Where coastlines remain in a natural state and are more or less undeveloped, dynamic and highly mobile coastal landforms and ecosystems such as beaches, dune systems, wetlands, saltmarshes and intertidal sand flats have the potential to adjust to rising sea-levels (Internal linkSharples et al. 2008). They are also able to adapt to changing groundwater levels and increased frequencies of inundation by migrating landwards, particularly when they are backed by low-lying soft-sediment environments that allow such migration. However, coastlines that are subject to development are less resilient to changes in sea-levels. In addition, if human responses to rising sea-levels are to defend the coast with artificial structures such as sea walls, existing potential for natural shoreline adjustment to the changing conditions will be reduced further. This will result in less natural shoreline and fewer areas for the retreat of vulnerable plants, animals and landforms.

Sea-level projections for the 21st century from the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR) of 2001 and the Fourth Assessment Report (AR4) of 2007 identify that observed sea-level is currently tracking near the upper limit of the IPCC model projections from the start date of the projections in 1990 (see Internal linkRahmstorf et al. 2007; Internal linkIPCC 2001; Internal linkIPCC 2007). The IPCC TAR Report model projections estimated a sea-level rise of between 9–88 cm by 2100. The IPCC AR4 model projections (with a 90% confidence range) revised this estimate and calculated a sea-level rise of between 18–59 cm by 2095 plus an allowance of another 10–20 cm for a potential dynamic response related to the melting of land ice in Antarctica and Greenland (see also Internal linkChurch et al. 2008; Internal linkIPCC 2007; Internal linkChurch et al. 2006; Internal linkEarth Observatory 2006). However, more recent published work suggests that a rise of up to 2 m is possible (Internal linkACE CRC 2008) and it could be more than 5 m by 2100 (Internal linkHansen 2007). CSIRO promotes the range 18–79 cm for Australia (Internal linkCSIRO 2009). Even with a rise of mean sea-level of approximately 50 cm, it is predicated that events which now happen every few years could occur every few days in 2100 and that larger increases in the frequency of extremes could occur in Bass Strait, along the coastline of Western Australia and capital cities such as Sydney, Brisbane and Hobart (Internal linkHunter 2007).

  • Sea-level measurements based on an early colonial tide gauge at Port Arthur suggest a rise of at least 13 cm, with an average annual rate of 0.8 mm/yr ± 0.2 mm/yr relative to the land in the southeast of Tasmania during the period 1841 to 2002 (Internal linkPugh et al. 2002; see also Internal linkHunter et al. 2003; Internal linkSharples 2006). Much of this rise has probably having occurred during the last century. The southward extension of the warmer EAC waters is also predicated to result in a sea-level rise above that of global background sea-level rise.
     
  • Data from the NTC indicates that the overall pattern of relative sea-level trends around the Australian coastline, including those at Burnie, Hobart and Spring Bay, is geographically uniform. Burnie (-1.5 mm/yr) is among five sites showing negative trends partly due to unstable tide gauge datum (particularly prior to 1975). The overall average relative sea-level rise around Australia is 1.2 mm/yr (Internal linkNTC 2007). This is consistent with a global average sea-level rise over the last 100 years of 1.7 ± 0.3 mm/yr (Internal linkChurch et al. 2005).
     
  • According to the Commonwealth Department of Climate Change, over 20 per cent of the Tasmanian coastline will be a risk from sea-level rise, erosion and recession, and more severe storm surges associated with climate change (Internal linkDCC 2008).
     
  • In areas where coastal flats grade up more gradually and any break of slope is less distinct, there may be a more significant increase in the areas flooded in these places under the maximum 2100 scenario as compared to the 2004 scenario (Internal linkSharples 2006). However, in many other flood prone coastal locations the land area that would be flooded under the maximum 2100 scenario is only a little greater than that which is potentially prone to flooding under the 2004 scenario. Although the 2100 maximum flooding scenario involves a significant rise in water levels, this extra rise is expected to create only a minor additional area of flooding since the increased flooding depth is accommodated by a minor horizontal extension over the more steeply-rising ground. Overall, approximately 247 km2 of Tasmanian coastal areas (including Bass Strait islands) would be flooded by 0.01% exceedance storm surge events by 2100 (Internal linkSharples 2006).
     

Artificial shorelines

Artificial shorelinesinternal SOE link to larger image

Artificial shorelines and reserve areas

Proximity of artificial shorelines to reserve areasinternal SOE link to larger image



Artificially Modified Coastlines - at a glance

This indicator reports on areas of artificial physical modification of shorelines around the Tasmanian coast. Artificial physical modification of shorelines is a major category of disturbance that not only affects geomorphic processes but also the physical integrity of significant coastal geoheritage sites. The data included in this indicator has been compiled by SoE Unit using the Tasmanian Shoreline Geomorphic Types dataset v1.0–v4.0 (2000–06).

  • Out of a total Tasmanian coastline length of 6,439 km (at 1:25,000 scale and including most offshore islands but excluding most small islets and rocks), 149 km (2.3%) is identified as wholly or substantially artificial.
     
  • Artificial shorelines include boulder shorelines, concrete walls and other seawalls, rock fill, causeways and channels, wharves, jetties and slipways, bridges, roads and railways, reclaimed land, houses and other infrastructure, old quarries and marram grass plantings.
     
  • The majority of artificial shorelines occur in areas outside the formal reserve system.
     
  • Examples of artificial coastlines include the Dunalley Channel, Clarence Point artificial shoreline to Garden Island near Beauty Point, Hobart waterfront, Lauderdale Channel and artificial shoreline, Midway Point causeway and artificial shoreline, and Stanley wharf and esplanade.
     

Dunalley

Denison Canal at Dunalleyinternal SOE link to larger image

Clarence Point

Clarence Point artificial shoreline to Garden Islandinternal SOE link to larger image

Hobart

Hobart waterfront artificial shorelineinternal SOE link to larger image

Lauderdale

Lauderdale channel and artificial shorelineinternal SOE link to larger image

Midway Point

Midway Point causeway and artificial shorelineinternal SOE link to larger image

Stanley

Stanley wharf and esplanadeinternal SOE link to larger image

Coastline exposure and wave energy

Coastline exposure and wave energyinternal SOE link to larger image



Vulnerability of Coastal Geodiversity - at a glance

This indicator outlines the vulnerability of various shoreline geodiversity types to erosion and recession caused by wave action and other hazards such as sea-level rise and storm surge flooding. Data was drawn from the Indicative Mapping of Tasmanian Coastal Vulnerability to Climate Change and Sea-Level Rise Project (see Internal linkSharples 2006). The assessment is not complete and further refinement of the assessment methodology, along with baseline monitoring and ground-truthing in the field, is planned.

Coastal landforms, and particularly sandy coasts, are one of the most mobile and dynamically changing geomorphic landforms in Tasmania. Coasts can, and do, change their physical form significantly over relatively short periods. This is a natural phenomenon. Coastal flooding and shoreline erosion have affected Tasmanian coasts repeatedly over the last 6,500 years during a period when the sea-level was mostly steady. More recent sea-level rise has been estimated at 10–20 cm during the last century (see Internal linkCSIRO 2008; Internal linkIPCC 2007; Internal linkChurch et al. 2001). Sea-level rise when combined with the affects of climate change are likely to increase or accelerate past coastal hazards where these existed previously, and initiate new phases of flooding and erosion on some shores that were previously in equilibrium.

  • The Indicative Mapping of Tasmanian Coastal Vulnerability to Climate Change and Sea Level Rise dataset includes mapping for approximately 84% of the Tasmanian coastline.
     
  • Of the 6,472 km of the Tasmanian coastline (including the Bass Strait islands and other major islands, but excluding Macquarie Island), approximately 2,220 km (34%) are sandy coastlines with substantial sand deposits in the upper intertidal zone that are potentially vulnerable to erosion and recession. They comprise 1,640 km (25%) subject to significant recession and 580 km (9%) subject to minimal recession hazard.
     
  • A further 2,175 km (33%) of non-sandy coastlines (that include muddy shorelines, soft clayey-gravelly or colluvial shorelines, and hard-rock sea cliff rock fall and retreat shorelines) are potentially vulnerable to erosion and recession. They comprise 260 km (4%) subject to significant recession hazard, 355 km (5%) subject to progressive recession hazard and 1,560 km (24%) subject to significant recession.
     
  • Gently to moderately sloping hard-rock shorelines (with or without rocky shore platforms) that were assessed as having low vulnerability shores to erosion and recession extend 1,260 km (19%).
     
  • Approximately 1,050 km (16%) of the Tasmanian coastline has yet to be classified. They comprise less common shoreline geomorphic types that are subject to different rates of erosion and recession.
     

Vulnerable sandy coasts

Sandy coastlines potentially susceptible to erosion and recessioninternal SOE link to larger image

Non-sandy vulnerable coasts

Coastlines potentially vulnerable to erosion and recessioninternal SOE link to larger image

Low vulnerability coasts

Coastline with low potential for erosion and recessioninternal SOE link to larger image

Vegetation clearance

Cleared and uncleared vegetation, 2007internal SOE link to larger image

Clearance by catchment

Vegetation clearance by catchment, 2007internal SOE link to larger image

Clearance by bioregion

Land clearance by bioregion, 2007internal SOE link to larger image



Native Vegetation Clearing - at a glance

This indicator aims to report on the rate of clearing (in ha/yr) of terrestrial native vegetation types, by clearing activity. The rate of vegetation clearing provides a measurable estimate of the potential threat to geodiversity. Clearing vegetation has significant effects upon hydrological processes (e.g. alterations to the catchment runoff/infiltration balance, erosion rates and sediment balance in rivers and estuaries, groundwater levels and stream flow regime). These alterations can modify karst, fluvial and coastal geomorphic processes. Land cover modifications within one catchment can also influence the fluvial geomorphic processes within adjacent catchments.

The data included in this indicator is compiled from a number of sources. These sources cannot be compared because they are based on different methods (e.g. TASVEG 1.3, Landsat satellite data for the Monitoring Vegetation Extent Project and Forest Practices Plans). They also have different reporting periods. The indicator outlines these key sources and the key limitations with these data.

  • From TASVEG, the total cleared area is approximately 1.54 million ha. After adding in the contribution from 'artificial' Hydro storages this becomes around 25% of the total area of Tasmania or 1.7 million ha (Internal linkTVMMP 2008).
     
  • The data indicates that as of 2006, the river catchments least disturbed by vegetation clearance are those in the west and south-west of the State, and to a lesser extent parts of eastern Tasmania north of Swansea. Catchments with <10% of their area cleared include Wanderer–Giblin (100 ha or nearly 0% of the catchment), Port Davey (20 ha or nearly 0% of the catchment), Great Lake (200 ha or 0.5% of the catchment), Nelson Bay (2,700 ha or 3.1% of the catchment), Pieman (17,900 ha or 4.3% of the catchment) and King–Henty (14,500 ha or 8.1% of the catchment).
     
  • The worst affected catchments in Tasmania in terms of vegetation clearance that extends across more than 50% of the catchment are generally along the north-west coast. They include cleared areas in the Cam (20,300 ha or 70.1% of the catchment), Duck (37,100 ha or 60.5% of the catchment), Inglis (37,200 ha or 60.2% of the catchment), Emu (14,800 ha or 58.5% of the catchment), King Island (73,500 ha or 54.6% of the catchment) and Meander (83,500 ha or 53.1% of the catchment) catchments. Other catchments with more than 50% of their area cleared include the Jordan (63,700 ha or 50.9% of the catchment) and Pittwater–Coal (48,500 ha or 50.2% of the catchment) catchments in the midlands and to the south of the State.
     
  • For the period, 2000–05, the MVEP identified 31,130 ha of vegetation change (from the original TASVEG vegetation mapped community). This change analysis identified that 12,340 ha of wet eucalypt forest and woodland and 10,670 ha of dry eucalypt forest and woodland were changed or converted over this period. These data can only be used at the Statewide level and are not available at the sub-catchment level or for karst analysis.
     
  • The External link: LegislationForest Practices Act 1985 requires the Forest Practices Authority to monitor and report on harvesting and reforestation activity in relation to the maintenance of a Permanent Native Forest Estate. A total of 7,981 ha of native forest were converted to other vegetation types (mainly plantation and agricultural land use) in 2007–08. The areas of highest native forest conversion were 2,202 ha (Ben Lomond), 2,009 ha (Woolnorth) and 1,394 ha (Central Highlands) RFA bioregions (Internal linkFPA 2008).
     
  • Overall, the reduction in the native forest estate over the period 1997–98 to 2007–08 amounts to approximately 132,122 ha (4.1% of the estimated 1996 native forest estate) as a result of conversion, mainly for plantation or agriculture. The proportion of native forest conversion by RFA designated bioregion (based on 2002 figures) varies from 9.9% (Woolnorth RFA Bioregion) to 0.2% (Furneaux RFA Bioregion) (Internal linkFPA 2008). Based on this assessment, the potential threat to geodiversity from vegetation clearance in the native forest estate is greatest in the Woolnorth RFA Bioregion followed by the Ben Lomond, D'Entrecasteaux, Midlands, Central Highlands, Freycinet, West and Southwest and Furneaux RFA bioregions.
     
  • The rate of conversion of native forest estate to plantation has decreased substantially from the total conversion figure of 13,672 ha in 2006–07 to 7,981 ha for 2007–08 (Internal linkFPA 2008).
     

Marram grass

Distribution of beach weed marram grassinternal SOE link to larger image

Marram grass

Marram grass (~sci;Ammophila arenaria~!sci;)internal SOE link to larger image

Rice grass

Distribution of rice grass (~sci;Spartina anglica~!sci;)internal SOE link to larger image

Rice grass

Rice grass (~sci;Spartina anglica~!sci;)internal SOE link to larger image



Weeds of Significance Present in Tasmania - at a glance

This indicator highlights the distribution of marram grass (Ammophila arenarias) and rice grass (Spartina anglica) in Tasmania. Information on these species was made available through the DPIPWE Weed Management Section and Parks and Wildlife Service (PWS) and is subject to some limitations that are detailed in the indicator. Other information is sourced from coastal values mapping projects known as the Coastal Values of Southern Tasmania (Internal linkDTAE 2007) and the Coastal Values of North East Tasmania (Internal linkDTAE 2007); and the assessment and mapping of foreshore values, condition and pressure in the southern NRM region (Internal linkMingus 2008).

Marram grass is an introduced perennial coastal plant was introduced from Europe over a century ago to stabilise coastal beaches and dunes. However, it spreads rapidly and over long distances. For example, along the southwest coast beaches, it has been found up to 110 km south from the nearest deliberate planting at Ocean Beach (Internal linkPWS 2003). Given its invasiveness, marram grass causes major changes to geomorphic processes in sandy coastlines. This is because marram tussocks effectively trap wind blown sand causing dune building around plants (Internal linkRudman 2003). Large steep faced dunes are also created that contrast with the lower angled foredunes that are associated with native vegetation. These dunes are more prone to wave attack and erosion. In addition, accumulation of sand within marram dune systems can also remove sand from beach, surf and inshore areas affecting sand movement and availability along coastlines. Where sandy coastlines in the State are significantly infested with marram grass, its establishment provides an indication that natural geomorphic processes have potentially been significantly altered in the area. More information on marram grass in Tasmania can be found in the Internal linkPlant Pests (Weeds) and Native Plant Diseases Issue Report.

Rice grass is a vigorous saltmarsh grass that was deliberately introduced from England to Tasmania initially in the late 1920s, but was continued to be planted along the banks of estuaries until the 1970s (Internal linkNHT and DPIWE 2002). For example, it was actively planted to improve navigability in the River Tamar in 1947 (Internal linkSheehan 2008). It has since become established in seven coastal regions in Tasmania, including Australia's two largest infestations, the River Tamar (420 ha) and the Rubicon Estuary (135 ha) (Internal linkDPIPWE 2009). This plant can cause changes to geomorphic processes because its dense growth habit and rhizomatic root network act as a trap for sediments and debris altering the natural rate, magnitude and location of sediment deposition and erosion. These processes elevate shorelines and river banks to create terraces and marsh islands by promoting deposition and accretion. Currently, there are six hotspots located near Smithton, the Rubicon and Port Sorell region, Tamar River, the Bridport region, Little Swanport and the Derwent Estuary near Dog Shear Pont, Old Beach and Elwick Bay. More information on rice grass in Tasmania can be found in the Internal linkEstuarine and Marine Pests and Diseases Issue Report.

  • Many weeds have invaded estuarine and coastal areas around the State including marram grass and rice grass. They pose a serious threat to geomorphic processes in coastal and estuarine systems.
     
  • Marram grass has established substantial healthy infestations in all bioregions of Tasmania over the last 100 years. No climatic factors limit its distribution. This species is particularly prevalent on the northwest and west coasts and southeast and east coasts.
     
  • The vigorous saltmarsh grass rice grass continues to inhabit the upper intertidal zone of a number of Tasmanian estuaries. Since 1997, rice grass infestations have been significantly reduced in the Derwent Estuary, and the Bridport and Little Swanport regions. It is believed that the hotspot in Georges Bay at St Helens has been eradicated and no new plants have been observed in the area for the past 5–6 years.
     
  • Rice grass infestations have increased in the Tamar Estuary, and in the Rubicon and Port Sorell regions. Rice grass infestations have also increased in the Smithton–Circular Head area. DPIPWE determined to only spray rice grass outside of a 'no spray area' in the Smithton–Circular Head area which has resulted in a significant expansion of rice grass infestation in an area including Duck River, Duck Bay, Deep Creek Bay and Big Bay (Internal linkDPIPWE 2009). In 2009, a significant area of previously unsprayed rice grass was detected and treated several kilometres upstream on a tributary of the Harcus River.
     
  • Fifty-three weed species were identified in the northern and southern NRM regions as part of the coastal values mapping project (Internal linkDTAE 2007; Internal linkDTAE 2007). More recently, in June 2008, North Barker Ecosystem Services published additional vegetation and fauna habitat data for NRM North and Cradle Coast in various sections from Macquarie Heads through to Weymouth (Internal linkNorth Barker Ecosystem Services 2008). In November 2008, Hydro Tasmania documented the coastal geomorphic values of western and northern Tasmania from Macquarie Heads through to Weymouth (Internal linkHydro Tasmania 2008).
     
  • Marram grass and rice grass (along with beach daisy, sea spurge, pyp grass and sea wheatgrass) were assessed as part of the foreshore habitat mapping project known as the Assessment and Mapping of Foreshore Values, Condition and Pressures for the Southern Natural Resource Management Region (Internal linkMingus 2008). The project found that there appears to be little threat from introduced pest species that were assessed as part of the study on most of the intertidal zone in the southern NRM region with <10% of coastline subject to moderate or high pressure. The southwest was assessed as being largely free from pressure posed by introduced species due to the remote and rocky nature of much of the coastline. However, it should be noted that due to the significant gaps in introduced species distribution data, this study should not be considered as a definitive assessment of all introduced species in the area.
     

Road density

Road density (km per 100 km squared), 2008internal SOE link to larger image

Walking track density

Density of walking tracks (km per 100 km squared), 2008internal SOE link to larger image

Walking track locations

Location of walking tracksinternal SOE link to larger image



Density of Road Networks and Walking Tracks - at a glance

This indicator reports on the density of roading in a region (e.g. catchments and areas of karst type) by providing a measure of the length of roading in each area. It also reports on the density of walking tracks in a region and provides a number of illustrative examples on where key walking tracks are found in the State. The data included in this indicator has been sourced from the DPIW Road Infrastructure Dataset (2008), Tasmanian Karst Atlas v.3.0 (2003) and the PWS Bushwalking Tracks Dataset (2008).

Roading, 4WD tracks, bike tracks and walking tracks provide access which gives rise to a range of pressures on the natural environment (e.g. ecosystems and karst, fluvial and coastal systems). They are often a precursor to changes in land use and land cover, which in turn, affect geology and geomorphological processes. In addition, the roads (and other tracks) themselves have significant effects on runoff rates, slope drainage patterns and flow regimes, as well as soil erosion rates and runoff turbidity. Changes (which will normally be increases) in roading and walking track density within a region will imply a higher likelihood of adverse impacts on the natural environmental processes within that region.

  • The greatest density of roads occur in the northern part of the State from Wynyard along the coast around Burnie, Devonport/Latrobe and George Town, the Tamar Valley and Launceston, and the north-east to Scottsdale. In the south of the State, the density of roads is greatest around Hobart and the outlying suburbs, Sorell and the Derwent and Huon valleys. The Smithton, Rosebery and St Helens areas have a greater road density than the remaining areas of the State.
     
  • Tasmanian catchments that have a road density <2 m/ha include the Port Davey (0.01 m/ha), Gordon–Franklin (0.9 m/ha) and Wanderer–Giblin (1.3 m/ha) catchments.
     
  • Eight catchments in Tasmania have a road density >20 m/ha including the: Derwent Estuary–Bruny (43.6 m/ha), Cam (30.3 m/ha), Tamar Estuary (25.3 m/ha), Emu (24.7 m/ha), Inglis (24.6 m/ha), Rubicon (22.4 m/ha), Little Forester (22.4 m/ha) and Blythe (21.2 m/ha). Since the 2003 SoE Report, the Blythe catchment has an increase in the recorded road density from 19.9 m/ha in 2003 to 21.2 m/ha in 2008. However, the increase may not only represent an increase in roads in the catchment (from 751,897 m in 2002), but also an adjustment to the calculation resulting from a re-alignment of the catchment boundary that reduced the size of the catchment from 37,718 ha to 37,000 ha.
     
  • At the Statewide level, there is 411,566 ha of karst where 3,426,329 m of roading has been identified. Road density on all karst is approximately 8.3 m/ha.
     
  • The greatest density of walking tracks occur at Cradle Mountain–Dove Lake and in Mount Wellington National Park (>40 km of walking tracks per 100 km2).
     
  • Other high density walking track areas include Lake St Clair and Mount Field National Park (30 – 40 km of walking tracks per 100 km2).
     
  • Areas such as the Arthur Ranges in the south-west, Rocky Cape on the north coast, Mount Roland–Mount Claude, Freycinet National Park, Maria Island, Cape Pillar on the Tasman Peninsula and Seven Mile Beach near Hobart have a track density of 20– 30 km of walking tracks per 100 km2.
     

Total sediment to rivers

Total sediment supply to rivers in Tasmania from erosion (t/yr)internal SOE link to larger image

Basslink, geo-monitoring

Geomorphology monitoring zones, Gordon Riverinternal SOE link to larger image

Basslink, net erosion rates

Gordon River monitoring: Net erosion ratesinternal SOE link to larger image

Lower Gordon River

Lower Gordon Riverinternal SOE link to larger image

Lower Gordon River erosion

Lower Gordon River estuarine bank average erosion rate, 1987 to 2008internal SOE link to larger image

Central Plateau Conservation Area

Erosion severity in the Central Plateau Conservation Areainternal SOE link to larger image

Macquarie Island erosion

Significant regions of erosion damage on Macquarie Island caused by rabbit grazinginternal SOE link to larger image



Potential Area Affected by Erosion - at a glance

This indicator highlights key information on erosion in the State as detailed below. This indicator provides information on both condition and pressure erosional processes because geological and geomorphological landforms can both be formed and damaged by past natural- or human-induced erosional events. Data were sourced from a systematic Statewide survey of water erosion (gully, tunnel, and sheet and rill erosion) that was conducted as part of a Statewide soil and land degradation assessment (Internal linkGrice 1995). Additional data and information were supplied by DPIPWE, Hydro Tasmania, the Tasmanian National Parks Association, and the Australian Natural Resources Atlas (in relation to river basin sediment budgets and erosion monitoring of the middle and lower Gordon River, and erosion on the Central Plateau and Macquarie Island). The following summary is subject to the data availability and limitations detailed within the indicator.

  • Large mass movement events: are relatively infrequent in Tasmania, although when they occur, they are dramatic and can result in permanent loss of geoheriatge. They are most frequent on slopes above 25° with little vegetation and high annual rainfall. There has been little work in Tasmania to assess the extent of mass movements since the 2003 SoE Report.
     
  • Wind erosion: wind detaches and transports sand and soil particles according to size: (1) >1 mm move by rolling (or soil creep); (2) 0.1–1 mm move by saltation (caused by the collision by entrained particles); and (3) <0.1 mm detach into suspension (and contributes to stream turbidity). Geomorphological features that have been formed by aeolian processes include relict inland systems from the last glacial age (e.g. deflation hollows and associated lunettes) and active coastal dune systems (often parabolic) such as the Henty Dunes near Strahan. There has been little work in Tasmania to assess the extent of wind erosion since the 2003 SoE Report. However, there have been reports of increased wind erosion in the Brighton area in the south of the State (Internal linkWaterhourse 2007) and in the Northern Midlands Municipality (Internal linkHerman et al. 2007). Approximately 16,000 ha of private land are recognised as containing a severe wind erosion hazard.
     
  • Splash, sheet, rill and tunnel erosion: is widespread in Tasmania with 15,500 ha classified as having severe to extreme splash, sheet and rill erosion risk (Internal linkDPIPWE 2009). These forms of erosion have the potential to adversely impact upon geomorphological features, particularly in areas where there is a lack of vegetative cover.
     
  • Gully erosion: is not appreciable in the State or it only occurs at a moderate level in areas usually associated with dispersive soils originating from Permian mudstones or Triassic sandstones.
     
  • Streambank erosion: is a major source of sediment in Tasmanian river systems. However, there has been little work in Tasmania to evaluate the extent of streambank erosion or other types of erosion into streams and rivers. Agricultural land has been assessed as part of the Australian Natural Resources Atlas and placed in the context of river basin sediment budgets (Internal linkAustralian Natural Resources Atlas 2007). More information on this assessment can be found though the External linkANRA website.
     
  • Gordon River geomorphology erosion monitoring: This monitoring is conducted by Hydro Tasmania as part of the Gordon River Basslink Monitoring Program (BMP) (Internal linkHydro Tasmania 2007; Internal linkHydro Tasmania 2008). More information on the BMP can be found in the report titled: Basslink Monitoring Program 2007–08 or through the External linkHydro Tasmania website.
     
    • The monitoring sites are distributed over 5 geomorphic zones. A number of geomorphology (3 out of 5) and riparian vegetation (19 out of 88) triggers were exceeded during 2007–08.
    • The results indicate that in general, the rate of erosion remained stable in 2006–07, while a large flood in August 2007 led to significant deposition in zones 3 and 4. In 2007–08, increased seepage erosion was recorded in zones upstream of the Denison River although the cause of this erosion has yet to be confirmed. According to Hydro Tasmania, the contribution of seepage erosion from power station operations to net erosion rates in the middle Gordon River remains an unresolved question.
    • In 2006–07, there were no significant Basslink changes in the caves and karst features, although some minor changes in sediments were observed in the caves. Slight net erosion was recorded in 2007–08, the majority of which occurred during the summer months. For example, Bill Neilson Cave and Kayak Kavern showed a relatively strong trend of winter deposition and erosion occurring during the summer months. There was no significant structural change recorded in the surrounding dolines (see also Internal linkBenjamin 2008).
     
  • Lower Gordon River monitoring: the lower Gordon River in the TWWHA has geological landforms of world heritage value that have been significantly eroded by vessel wave wake for over 25 years (Internal linkDPIW 2005). When erosive wake waves from vessels accessing the river hit the river bank, fine sediment is suspended and potentially removed from the landform system by currents. Erosion appears to have begun suddenly in the mid-1980s when large, fast tourist cruise vessels replaced smaller and slower tourist boats. Prior to this time, the river banks had generally been actively depositional and encroaching upon the channel, or stable for at least 1,400 years. Erosion pin monitoring (that commenced in 1987) has shown that a decline in erosion rate coincident with the management changes that imposed speed and access restrictions on the operation of commercial cruise vessels is 'providing evidence that wave wake is a significant driver of contemporary geomorphic process' (Internal linkDPIW 2005). Since 1997, the average erosion rate to the river banks has stabilised at less than 15 mm/yr.
     
  • Central Plateau: contains many sites of geological significance and some of the most degraded alpine and subalpine country in Australia with 11,000 ha known to be affected by some degree of erosion (Internal linkCullen 1995), which is the result of past overgrazing and the impacts of rabbits (Internal linkNRM South 2005).
     
  • Macquarie Island: little is known about erosion of geomorphological sites on offshore islands around Tasmania. However, overgrazing by rabbits (that are estimated at over 100,000) on Macquarie Island has caused serious vegetation degradation and widespread and severe erosion damage to particularly on steep destabilised coastal slopes (Internal linkTNPA 2007; Internal linkDTAE 2008). In 2006, 20 landslips were recorded in one month alone and some hillslopes have been completely washed away (Internal linkWWF-Australia 2007).
     

Sheet and rill erosion

Areas of potential sheet and rill erosion hazard on private landinternal SOE link to larger image

Gully erosion

Areas of potential gully erosion hazard on private landinternal SOE link to larger image

Tunnel erosion

Areas of potential tunnel erosion hazard on private landinternal SOE link to larger image

Areas of reserved land

Areas of reserved landinternal SOE link to larger image

Reserve classes

Reserve classesinternal SOE link to larger image

Key geoheritage in CAR Reserve System

Internationally, nationally and State listed sites of geoconservation significance held within the CAR Reserve System in Tasmania, 2008internal SOE link to larger image

Karst in CAR Reserve System

Karst found within the CAR Reserve System in Tasmaniainternal SOE link to larger image



Geoheritage Protection - at a glance

This indicator details the extent of karst found within the CAR Reserve System and new reserves that have been established in karst areas since the 2003 SoE Report. Data was sourced from the Tasmanian Karst Atlas v.3.0 and the LIST held by DPIPWE. It also details karst reserved under the Community Forest Agreement (CFA).

  • Of the 400,000 ha or about 6% of the State that forms the Tasmanian karst estate, approximately 222,550 ha of karst (approximately 55% of carbonate rocks in the State) is found within the CAR Reserve System (Internal linkEberhard 2007). This comprises 95,600 ha of intensely karstified or probably intensively karstified land, 53,750 ha of substantially karstified or probably substantially karstified land, 10,500 ha of partially karstified or potentially partly karstified land, and 62,650 ha of possibly partially karstified land (see Internal linkEberhard 2007).
     
  • In the order of 133,050 ha is protected in dedicated formal CAR reserves such as National Parks, State Reserves, Nature Reserves, Game Reserves, Historic Sites and Wellington Park.
     
  • An additional 67,200 ha is protected in Conservation Areas, Regional Reserves, Nature Recreation Areas and Forest Reserves and 19,900 ha is protected in informal CAR reserves such as informal reserves on State Forest and other public land.
     
  • A further, 2,400 ha is protected in Private Nature Reserves, Private Sanctuaries, properties with conservation covenants, and other privately held land within the TWWHA.
     
  • The CFA process reserved 13,570 ha of karstic and potentially karstic rocks. CFA formal reserves (6,323 ha) protect areas of dolomite karst on the Donaldson, Little Donaldson and Savage rivers in north-west Savage River Pipeline Forest Reserve. CFA informal reserves (7,247 ha) protect areas of magnesite karst at Main Creek in the south-west, dolomite karst in the Styx Valley and north of Corinna, and limestone karst in the Florentine Valley.
     
  • New reserves of karst established since the 2003 SoE Report cover approximately 1,360 ha of land in the north-west of the State comprising 774 ha in the Mole Creek area, 474 ha at Vale of Belvoir, 61 ha at Gunns Plains and 51 ha in a Private Nature Reserve at Loongana (Internal linkDPIW 2008). The karst reserves have been established under a range of Tasmanian and Australian government led programs including PAPL, Private Forest Reserves Program (PFRP), Natural Heritage Trust Priority 1 Karst Program (NHT), Forest Conservation Program (FCF), TLC, and the Crown Land Assessment Classification Project (CLAC).
     



Management responses

In addition to the TGD, Digital Tasmanian Karst Atlas, Fluvial Systems Project, Tasmanian Shoreline Geomorphic Types Digital Line Map, and Tasmanian Quaternary Coastal Sediments Digital Polygon Map there have been a range of management responses and projects that have been established since the 2003 SoE Report to report on geoheritage in Tasmania and help conserve these sites. Some of these key responses, and other related programs, projects, frameworks and initiatives are listed below.

Geodiversity management legislation

In an effort to protect sites of significant geological values, the External link: LegislationRegional Forest Agreement (Land Classification) Act 1998 was the first direct recognition of 'geological diversity' under Tasmanian legislation (Internal linkHoushold and Sharples 2008). These provisions were then incorporated in the External link: LegislationNature Conservation Act 2002, External link: LegislationCrown Lands Act 1976; External link: LegislationNational Parks and Reserves Management Act 2002 and the associated Forest Practices Code 2000. Under these Acts, geological diversity means 'the natural range of geological, geomorphological and soil features, assemblages, systems and processes' in specific contexts. The External link: LegislationWellington Park Act 1993 also refers to the preservation of any features of geomorphological interest. In addition, the External link: LegislationMineral Resources Development Act 1995 states that a person must not disturb, collect or remove any speleothem (cave formation) from a cave without written approval, and the associated Mineral Exploration Code of Practice 1999 includes guidelines for protecting geoconservation and geological heritage. These provisions may be relevant in some situations of 'environmental harm' arising on private land from 'gross' acts of negligence as outlined in External link: LegislationEnvironmental Management and Pollution Control Act 1994. However, despite these various provisions, Tasmanian legislation does not provide for holistic protection for geoconservation values through statutory mechanisms at the landscape level.

Local government planning schemes in some municipalities now require development applications to address geoconservation values where they are identified as being present in the landscape. For example, off-reserve karst management on public and private land has continued to have a high profile at Mole Creek. A draft planning scheme released by the Meander Valley Council in 2007 contains a karst schedule specifying performance criteria and acceptable standards for minimising adverse impacts to the local karst system (Internal linkMeander Valley Council 2007). The schedule is underpinned by mapping that identifies different zones within the karst based on criteria for environmental sensitivity.

Management policies and strategies

The Tasmanian Reserve Management Code of Practice 2003 specifies appropriate standards and practices for new activities in land-based reserves, and underpins management of formal reserves by the PWS and Forestry Tasmania. Geoconservation values are addressed in detail where conservation is 'achieved primarily through the protection and maintenance of geological (rock), geomorphological (landform) and pedological (soil) features, systems and natural ecosystem processes' (Internal linkPWS et al. 2003). The Reserve Code complements the geoconservation provisions of other major State codes of practices such as the Forest Practices Code 2000 and Mineral Exploration Code of Practice 1999. The State Coastal Policy 1996 (Internal linkDTAE 1996) and Proposed State Coastal Policy 2006 (Internal linkDEPHA 2006) also refer to the protection of geology and geoheritage places.

The Board of the Environment Protection Authority (EPA) has produced guidelines to assist proponents prepare Development Proposal and Environmental Management Plan (DPEMP) assessments and environmental management plans for Level 2 activities under the External link: LegislationEnvironmental Management and Pollution Control Act 1994 (Internal linkEPA 2008). Section 4.7.2 (e) of the guidelines requires proponents to consider 'effects on sites of geoconservation significance or natural processes (such as fluvial or coastal features), including sites of geoconservation significance listed on the Tasmanian Geoconservation Database'. The guidelines aim to promote a more integrated approach to considering geoconservation values in the planning and assessing of major developments.

DPIPWE has developed a Consultants Brief regarding the minimum requirements for information needed to enable the Tasmanian Government to assess the potential impact/s of proposed activities on biodiversity and geodiversity (Internal linkDPIW 2004). Consultant reports may be required as part of, for example, a DPEMP assessment, a local government planning submission, or a community group wishing to undertake rehabilitation works. An assessment of significant geoheritage and relevant conservation activities is required if a site is listed on the TGD.

As part of the regional Natural Resource Management (NRM) strategy development process, position papers have been developed for geoconservation and geodiversity (including rocks, karst, rivers and coasts) by NRM South and NRM Cradle Coast (Internal linkNRM South 2003; Internal linkNRM Cradle Coast 2003). Information presented in these documents has been used to inform the development of resource management strategies for the northern, southern and Cradle Coast NRM regions (Internal linkNRM Cradle Coast 2005; Internal linkNRM North 2005; Internal linkNRM South 2005). These position papers and strategies recognise that there has been a limited assessment of the condition of Tasmania's geodiversity. Key issues identified in the strategies that relate to geoconservation in the NRM regions include:

  • damage to karst systems from disturbance in catchments, impacts from poor water quality, forestry, quarrying, tourism developments and fire;
  • erosion, sedimentation, flow regulation and sediment extraction of rivers;
  • damage to riverine, coastal and fossil sites;
  • damage from collection of geological materials; and
  • fire effects on fragile peats.

Various management plans have been developed by the NRM regions to identify and protect sites of geoconservation significance. For example, NRM North and Bushways Environmental Services developed a Coastal Management Plan for Tomahawk in 2008 that includes actions to protect the north-east Tasmanian Pleistocene aeolian system that covers most of the Tomahawk area (Internal linkNRM North and Bushways Environmental Services 2005).

Other management plans have been completed for a number of areas of high geoconservation significance managed by PWS. The plans prescribe policies and actions for protection of geodiversity. They include the Macquarie Island Nature Reserve and World Heritage Area Management Plan 2006 (Internal linkPWS 2006), Mole Creek Karst National Park and Conservation Area Management Plan 2004 (Internal linkPWS 2004), The Nut State Reserve Management Plan 2003 (Internal linkPWS 2003), Moulting Lagoon Game Reserve (Ramsar Site) Management Plan 2003 (Internal linkPWS 2003), Kent Group National Park (Terrestrial Portion) Management Plan 2005 (Internal linkPWS 2005) and Southport Lagoon Conservation Area, George III Monument Historic Site and Ida Bay State Reserve Management Plan 2006 (Internal linkPWS 2006). Recent closure of the Leprenna Track under the Southport Lagoon Conservation Area Management Plan has alleviated a source of serious ongoing damage to organic soils. Work has also commenced on the preparation of a management plan for caves and karst on land managed by PWS in its Southern Region administrative unit.

Many of the features found in the TWWHA are listed internationally as sites of geoconservation significance and included on the World Heritage List. However, this list has been criticised for it focus on biodiversity values and its failure to adequately represent areas and sites of geological significance (the exception of a relatively few fossil sites). The Global Indicative List of Geological Sites (GILGES) was also established in the early 1990s by the United Nations Educational, Scientific and Cultural Organization (UNESCO), IUCN and International Union of Geological Sciences (IUGS). This list includes hundreds of geoconservation sites that are considered to be of 'first-class' importance, representing outstanding examples of the Earth's history and significant ongoing geological processes (see Internal linkGray 2004). The GILGES has been modified and reworked since the initial compilation and now includes natural networks of sites that 'represent' geodiversity. Geoparks have also been established since 2004 to protect internationally significant geological heritage and officially endorsed by UNESCO as an integral part of their network/system of protected areas together with sites on the World Heritage List and the Man and the Biosphere Network of Biosphere Reserves (the Biosphere reserves network). Although Tasmania has yet to establish a Geopark, they may offer an additional management option in the future. More information on Geoparks is provided in the embedded document Internal linkGeoparks in Australia or through the External linkUNESCO website.

Other programs, projects, frameworks and initiatives

Collaborative efforts to identify geoheritage and protect sites of significance are continuing to grow in Tasmania. Government agencies, local government, private industry, NRM groups, non-government organisations and private landholders are increasingly coming together to implement management programs and plans of action to protect geoheritage on public and private land. For example, DPIPWE, PWS, Forest Practices Authority (FPA), Hydro Tasmania and NRM regions all provide information on geomorphology and various actions to protect significant sites on their websites, with most management documents, guidelines and brochures made available for download.

  • The Fluvial Systems Project has been further developed since 2003 (see Internal linkJerie et al. 2003). DPIPWE, in partnership with NRM regions and Greening Australia, has monitored geomorphic aspects and determined reference condition sites for a number of river reaches across the State. In addition, pilot studies have been completed for the Leven, St Patrick and Coal rivers in more detail.
     
  • The TRCI rapid assessment approach to evaluate river health has been further developed by the Tasmanian Government in partnership with NRM regions, Earth Tech/Maunsell, Hydro Tasmania and the National Heritage Trust (NHT). The results will also be used to inform State policy and NRM investment priorities and provide the basis from which priorities for management and rehabilitation of rivers can be identified. At the time of writing this SoE Report, information was being collected from a range of rivers and reported at a Statewide scale.
     
  • The CFEV Project has contributed baseline data for TRCI. The work has involved identifying spatially representative units of a biological or physical (geological/geomorphological) class, developing a 'naturalness' score (or N-score) as part of an overall index of river condition, and assessing 'distinctiveness' to allow CFEV assessments to incorporate sites of geo-significance into an Integrated Conservation Value (ICV). As part of this process, CFEV has included an assessment of 334 karst systems and associated freshwater-dependent ecosystem values and considers karst associated with distinctive terrain, landforms and drainage characteristics resulting from the relatively high solubility of certain rock types in natural waters (Internal linkDPIW 2008). All outputs of the CFEV assessments have been put into a geo- (spatial) database (Internal linkDPIW 2008).
     
  • Landform mapping and groundwater tracing has improved knowledge of the karst resource and supported the development of sustainable land management practices appropriate to the karst systems in a number of areas (i.e. Mole Creek, Florentine Valley, Hustling Creek and Hastings Cave region). At the time of writing this SoE Report, an audit of cave condition was being undertaken by DPIPWE to highlight sites at risk and is assisting to establish priorities for cave management.
     
  • There has been significant progress towards protecting karst landforms through reservation on public and private land, with important additions to the highly fragmented reserve system at Mole Creek and other locations around the State. A number of Tasmanian Government programs have contributed to the protection of these karst areas including PAPL, PFRP and the Crown Land Assessment Classification (CLAC) Project. At the Commonwealth level, NHT and the Forest Conservation Fund, in partnership with TLC, established the voluntary Mole Creek Karst Forest Programme (Internal linkTLC 2006; see also Internal linkDEWHA 2007). The Programme was designed to financially assist landowners at Mole Creek to protect the forest over karst on their property by selling (via a revolving environmental fund) and/or covenanting their land. It aimed to protect up to 2,400 ha of private forested land in the Mole Creek area with funding capped at $3.6 million, as part of the Tasmanian Community Forest Agreement. By 2006–07, the Programme had secured the protection of 66 ha of forest and limestone karst on private land (Internal linkDEWR 2007). Four of the eight properties that were secured have been added to the Mole Creek National Park and it was planned to resell two of the covenanted properties (Internal linkTLC 2008).
     
  • Industry and community groups have also come together to protect karst systems. For example, the Mole Creek Karst Forest Programme Guidance Group (MCKFP) was established in 2006 to assist in guiding the Mole Creek Karst Forest Programme and represent the community's views (Internal linkDEWHA 2008). MCKFP comprises of representatives from Timber Communities Australia, Tasmanian Farmers and Graziers Association (TFGA), NRM North and TLC. NRM North also published a brochure titled Living With Karst to raise community awareness about karst issues and promote integrated property management planning (Internal linkBenjamin 2008).
     
  • The Fire Impacts on Fluvial Geomorphology and Hydrology of Buttongrass Moorlands Project was implemented in 2004 in partnership with DPIPWE, PWS and researchers from the University of Tasmania in response to the identification of fire as a priority research area in the TWWHA. Although fire is a natural ecosystem component of buttongrass moorlands, and is used as a management tool to maintain ecosystem health, the impact of fire on the peat soils, catchment hydrology and geomorphology has been largely unquantified. Up until late-2008, the research program had collected approximately four years pre-fire data and a controlled management burn is planned during 2009. It is anticipated that data collection will continue for four years post-burning. Outcomes from the research will include a greater understanding of the geomorphology and hydrology of moorland catchments under long-term unburnt and recently burnt environmental conditions. Environmental parameters of interest include catchment rainfall-runoff relationships, water quality, and geomorphological processes such as stream channel morphology and sediment transport. The project also aims to identify potential degradation of peat soils resulting from fire management practices, and assess the time required to return these soils to a pre-burn condition. The improved understanding of buttongrass moorlands developed through this research will be used to inform management burn prescriptions and wildlife threat assessment, including a better estimation of the frequency of fuel reduction burns.
     
  • Researchers and forest managers continue to undertake site specific surveys in forestry areas to ensure non-wood values, including geomorphic features, are assessed as part of forest-practices planning processes and before forest disturbance activities commence (as required by the Forest Practices Code 2000 and the Tasmanian Reserve Management Code of Practice 2003). The surveys are intended to identify natural values that may be affected by proposals and any actions required to avoid or mitigate negative impacts, and provide baseline data for future monitoring and assessment (Internal linkState of Tasmania 2007). Research is also continuing in the Warra Long Term Ecological Research Site to provide a focal area for research into wet eucalypt and the projects are progressively documenting the climate, geomorphology, soil mapping, hydrology and aquatic and terrestrial biodiversity of the research area. More information on the Warra Site can be found on the External linkWarra Site website.
     
  • There has been some targeted erosion monitoring of Tasmanian rivers and streams to assess the affects of human-induced impacts on evolving fluvial and karst landforms by government agencies, and private industry such as Hydro Tasmania and tourist operators. For example, geomorphology erosion monitoring has been conducted on the middle Gordon River by Hydro Tasmania as part of the Gordon River BMP since 2006 to monitor the erosive affects of the Gordon Power station operations under Basslink. Riverbank stability and erosion-sedimentation regimes in karst caves and dolines are a focus of this work. Monitoring of bank erosion on the middle Gordon River indicates that generally, the rate of erosion remains stable.
     
  • Following an assessment of erosion impacts from tourist vessels and recreational boats on the lower Gordon River, revised wave wake criteria for vessel operation were introduced in 2005 to further reduce erosion of the river banks from these vessels and boats (Internal linkDPIWE 2005). Note that: in an effort to control erosion of the river banks the Tasmanian and Australian governments first imposed speed and access restrictions in 1989 (and further restrictions in 1994 and 1998) on cruise vessels to reduce the size of the wave height they generated (see also Internal linkDPIWE 2004). The new criterion specifies a maximum wave height of 75 mm for commercial cruise vessels to minimise bank erosion by wave wake and the active discouragement of other boating visitors from travelling at a speed greater than approximately five knots. At the time of writing this SoE Report, small private vessels were not subject to any speed limit and may have a disproportionately large impact. Management restrictions on the operation of commercial cruise vessels on the lower Gordon River have considerably slowed, but not halted, erosion of the now destabilised banks. More information on erosion of the Lower Gordon River is provided in the Internal linkPotential Area Affected by Erosion Indicator or through the DPIPWE External linkWave Wake and Erosion: Lower Gordon River website. A brochure to promote increased understanding of the threat to bank stability by boat wakes on rivers and estuaries has been produced by DPIPWE and distributed to boat owners in collaboration with Marine and Safety Tasmania. The brochure can be found through the DPIPWE External linkWake up? Slow down! website.
     
  • DPIPWE, through a World Heritage Area funded project, has undertaken work on developing rehabilitation priorities for land affected by broad scale erosion on the Central Plateau in 2005–06 (Internal linkStorey and Comfort 2007). This work has highlighted a number of knowledge gaps including questions concerning declining trends in the condition of degraded land and geomorphic features and practicable rehabilitation options where appropriate. Further work by DPIPWE is attempting to address some of these issues.
     
  • DPIPWE (formerly comprising sections from DPIW and the Department of Environment, Parks, Heritage and the Arts) commenced implementing the Plan for the Eradication of Rabbits and Rodents on Subantarctic Macquarie Island in late 2007. The eradication program will take up to seven years with the aim of reducing rabbit numbers to reduce vegetation loss due to rabbit grazing and the consequential destabilisation and erosion of steep peat-covered slopes. Further information on the eradication efforts can be accessed through the PWS External linkMacquarie Island Pest Eradication Project website.
     
  • TLC has worked with PLCP and Bush Heritage to develop landscape scale conservation planning and create private protected areas to conserve significant forest and sites of geodiversity as part of the NRS. TLC also purchased the Egg Islands near Huonville in 2008 to protect the areas natural values (Internal linkTLC 2008).
     
  • Researchers at the University of Tasmania commenced work in 2007 on producing a geomorphic map of the Australian coastline using a nationally-consistent landform classification system. This national approach has been largely modelled on the approach developed in Tasmania, and it is anticipated that it will be useful for assessing coastal vulnerability to sea-level rise and a range of other applications including input into the national Oil Spill Response Atlas (Internal linkSharples 2007).
     
  • Geoscience Australia, in partnership with the NLWRA and the former Cooperative Research Centre for Coastal Zone, Estuary and Waterway Management (Coastal CRC), launched the OzCoasts web-based database and information system in late 2008 (Internal linkAustralian Government 2008). OzCoasts currently consists of six inter-linked modules including search data, conceptual models, coastal Indicators, geomorphology and geology, environmental management and NRM reporting. For more information on the condition of Tasmania's coastal areas can be found though the External linkOzCoasts website.
     
  • Criteria for establishing marine protected areas (MPAs) under the Tasmanian Marine Protected Areas Strategy 2001 do not include reference to geoconservation values. However, the Resource Planning and Development Commission (RPDC) took into account the presence of sites of geoconservation significance listed in the TGD in its recommendations report on MPAs in the Bruny Bioregion (Internal linkRPDC 2008). The RPDC identified that marine and coastal areas around Tasmania contain a range of significant and sensitive geoconservation features such as the geomorphology and habitats of Hippolyte Rocks, Cape Pillar and Tasman Island.
     

  External linkTasmanian Planning Commissioninternal SOE link to larger image

  Contact the Commission on:

email: External linksoe@justice.tas.gov.au
Phone: (03) 6233 2795 (within Australia)
Fax: (03) 6233 5400 (within Australia)
Or mail to: Tasmanian Planning Commission, GPO Box 1691, Hobart, TAS, 7001, Australia

 


Last Modified: 1 Mar 2010
URL: http://soer.justice.tas.gov.au/2009/nat/4/issue/66/index.php
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