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Tasmania is well endowed with unique animals and plants of which many are endemic to the State. Some endemic species have evolved in Tasmania while others were once more widespread but are now restricted to Tasmania. Tasmania retains the most ecologically diverse group of large marsupial carnivores, the largest tracts of cool temperate rainforest in Australia and Tasmania's cave fauna is amongst the most species rich in temperate Australia. Tasmania also has many remnants of native grasslands which are home to a multitude of native plants and animals. All of these special biodiversity features are under pressure from human impacts caused by inappropriate land use practices, introduced pests and diseases. Assessing and measuring the current situation Native grasslands Temperate grasslands have been identified as one of the most threatened plant communities in Australia, and remnant lowland native grasslands are one of the most threatened and fragmented ecosystems in Tasmania and Australia. Native grasslands once covered approximately 2 million ha of Australia at the time of European settlement (Barker 1999). By 1993 it covered approximately 10,000ha, only 0.5% of its original area. The extent of native grasslands in Tasmania prior to European settlement is unknown, but it has been estimated at 85,000ha (Kirkpatrick 1999). There was greater than 11 000ha of lowland native grassland and 44,000ha of highland grassland remaining in 1984; and since that time lowland grassland has been cleared for cropping and pasture at a rate of 1.27% pa while the highland grassland has been cleared at less than 0.2% pa (Barker 1999). Tasmania's Nature Conservation Strategy estimates that there was around 51,000ha of grassland in Tasmania in 1996 (State Biodiversity Committee 2002). Some of the present native grasslands are artefacts of European land management practices, such as tree clearing, the removal of tree regeneration by intense stock grazing, rural tree dieback and roadside management (Barker 1999). Some substantial areas of lowland grasslands on Flinders and Cape Barren Islands have been created by repeated burning of areas once occupied by closed forest (Barker 1999). Lowland native grasslands occur in four distinct ecological types, three pre-date European settlement. These are the valley bottom grasslands, rock plate grasslands, coastal grasslands and the disturbance induced grasslands (Barker 1999). The valley bottom grasslands are the most extensive. Silver Tussock Grass (Poa labillardieri) dominates the valley bottom and highland grasslands while Kangaroo Grass (Themeda triandra) and Wallaby Grass (Danthonia spp. ) are dominant elsewhere (DPIWE 2003; Barker 1999). Grasslands support a huge variety of native Australian plants and animals. Forty-nine of the species are listed in Commonwealth and State threatened species legislation of which eight are listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Barker 1999). One is presumed extinct and one other is confined to roadside verges, presumably by the pressures of domestic stock grazing (Barker 1999). The grasslands of the Northern Midlands support a number of regionally endemic plant species. These include three threatened orchid species, the Tunbridge Leek Orchid (Prasophyllum tunbridgensis), the Midlands Greenhood (Pterostylis commutata) and the Pungent Leek Orchid (Prasophyllum olidum) (Gouldthorpe and Gilfedder 2002). The Tunbridge Buttercup (Ranunculus prasinus) is also endemic to the region and occurs in Poa dominant tussock grassland (Gouldthorpe and Gilfedder 2002). The Eastern Barred Bandicoot (Perameles gunnii gunnii) relies on native grasslands as a foraging source for grubs beneath the soil (DPIWE 2003). The degradation of native grasslands and the introduction of predators such as cats and foxes have caused rapid decline in bandicoot numbers. Northern Midland grasslands are also home to three species of grass skink, one of which is the regionally endemic Tussock Skink (Pseudemoia pagenstecheri), and the endemic and threatened Ptunarra Brown Butterfly (Oreixenica ptunarra) (DPIWE 2003). Native grasslands are also the natural diet of grazing species like wombats and are the preferred habitat of the bettong.
Threats The Recovery Plan for Tasmanian Native Grasslands identifies 6 main threatening processes that affect native grasslands (Barker 1999). These are listed below. Management Responses A recovery plan for lowland temperate grasslands in Tasmania was initially completed in 1993, but was not adopted by the Commonwealth. The purchase and resale of land under a protected covenant was recommended by the plan but was rejected by the Commonwealth on the basis of expense. The DPIWE commissioned the completion of a recovery plan for Tasmania's native grasslands and was later adopted by the Commonwealth in 1999. The objectives of the recovery plan aim to: Tasmania still has not secured a significant parcel of grassland for the National Reserve System. The 16ha Township Lagoon Nature Reserve is the only formal reserve supporting non-coastal lowland grassland (Barker 1999). The reserve contains some excellent examples of high quality grassland with many threatened grassland species. However, the reserve is very small and is threatened with deterioration caused by pollutants from the adjacent rubbish tip, fertiliser from the surrounding fields, vehicle use and weed invasion (Barker 1999). According to Tasmania's Nature Conservation Strategy, only 1,289ha of grassland and grassy woodland are reserved which constitutes around 1.2% of the total area (State Biodiversity Committee 2002). Most native grasslands occur in road reserves. The government authority responsible for main roads has developed a database and administrative mechanisms designed to involve nature conservation in road management and planning (Barker 1999). Unfortunately, management protocols have failed in some instances resulting in the destruction of significant grassland remnants. Local councils manage many of the most significant roadside grassland remnants, but despite coordination attempts with Greening Australia there has been no useful reduction in the rate of destruction of these remnants (Barker 1999). There are some grassland remnants on vacant Crown Land or in second class reserves (e.g. coastal kangaroo grass dominant grasslands in the Waterhouse Point Conservation Area and vacant Crown Land adjacent to Bridport) (Barker 1999). These are both potentially subject to sell off for development or degradation through recreational use. Opportunities for the reservation of grasslands on public land are limited. It is therefore necessary to acquire representative grassland communities on private land through management agreements. According to Tasmania's Nature Conservation Strategy many off-reserve conservation programs are underway including voluntary reservation of private land by landowners promoted by the State Government, Greening Australia and the Threatened Species Network (State Biodiversity Committee 2002). To date very little has been done to manage and protect non-forest vegetation. According to Tasmania's Nature Conservation Strategy no classification or inventory of any non-forest vegetation community has been completed and no analysis of conservation needs, targets for reservation or strategies for off-reserve management have commenced (State Biodiversity Committee 2002). Cool Temperate Rainforest Tasmania contains Australia's largest tracts of cool temperate rainforest, covering around 10% of the State. Temperate rainforest is very different to rainforest found in warmer climates as there are no trees with buttress roots, palm trees and very few climbing plants. However, ferns, mosses, lichens and fungi species thrive in Tasmania's rainforests. Most Tasmanian rainforests grow in areas that receive over 1,200mm of rain a year, but some isolated patches occur in drier areas. Tasmanian rainforests contain some of the most ancient species of Australia's flora. Many of these species have evolved from ancestors that date back to over 60 million years ago when the southern continents were joined together as a landmass called Gondwana. Temperate rainforest is dominated by particular trees such as Myrtle Beech (Nothofagus cunninghamii), Leatherwood (Eucryphia lucida), Celery-top Pine (Phyllocladus asplenifolius), Sassafras (Atherosperma moschatum), Huon Pine (Lagarostrobus franklinii), Pencil Pine (Athrotaxis cupressoides), King Billy Pine (Athrotaxis selaginoides), and Deciduous Beech (Nothofagus gunnii) (DPIWE 2001).
Threats There are a number of potential threats to Tasmania's temperate rainforests. This review is focussing on the threats posed by fire, myrtle wilt (Chalara australis) and root rot (Phytophthora cinnamomi). Fire Fire poses the biggest threat to temperate rainforest in Tasmania where most fires result from either deliberate or accidental burning. In the last century over 7% of Tasmania's rainforest have been burnt (DPIWE 2001). Rainforest plant species do not require a disturbance such as fire to reproduce, unlike much of the sclerophyll vegetation (eucalypts and acacias). Tasmania's native conifers (the pines) and myrtle beech trees are very susceptible to fire. Some of the largest pure stands of Pencil Pine have been lost due to burn-offs that have escaped from target areas, and one-third of the State's King Billy Pines have been destroyed by fire (DPIWE 2001). Rainforests can recover after fire provided the fire is of low intensity and that all plants are not killed and the peat soils have not been consumed in the fire. Peat soils are very susceptible to erosion particularly after the occurrence of fire. Following a fire in a rainforest area the vegetation often passes through several regeneration stages and if left undisturbed the area may return to mature rainforest after one hundred years or more (DPIWE 2003). Some species may never recover due to their slow growth habit and poor seed dispersal abilities. Many of the fire-sensitive rainforest communities often occur adjacent to highly flammable communities such as buttongrass moorlands, particularly in the State's southwest (DPIWE 2003). The leaves of moorland plants are woody and sometimes contain oils making them highly flammable. Moorland plants are highly adapted to frequent fires helping to maintain the vegetation communities through the removal of invading forest species and the depletion of soil nutrients (DPIWE 2003). Myrtle Wilt (Chalara australis) Myrtle wilt is a naturally occurring fungus that causes myrtle beech trees (Nothofagus spp. ) to die. In undisturbed forest, myrtle wilt acts primarily as a mechanism to facilitate forest rejuvenation (Packham 1994). It enters the tree through an exposed wound caused naturally when tree limbs are broken off during a storm, but is increased by human disturbance, notably logging. Mature myrtle trees are susceptible to death from myrtle wilt caused by the fungus Chalara australis (Kile & Walker 1987). Disturbances to rainforest stands, such as logging or thinning treatments, increase mortality due to myrtle wilt (Packham 1991). Early literature, aerial surveys and photographs indicate that myrtle wilt was endemic to at least part (and possibly most) of the range of myrtle in Tasmania, but in some areas disease levels may have increased in the recent past (Packham 1994). Phytophthora cinnamomi Phytophthora or root rot is a fungus found in the soil and on plant roots. Within Tasmania there are 181 species recorded as being hosts for Phytophthora with considerable variation occurring in response to infection among different species (DPIWE 2003). Phytophthora spreads through soil and water movement and is also carried by machinery, foot ware and other equipment. Forestry activities and bushwalkers are therefore a potential vector for the fungus. Phytophthora can be a major problem in rainforests, especially on recently burnt sites. Thirty-nine rainforest species are known to be susceptible to infection, of which 15 are threatened including 6 endemic species (State Biodiversity Committee 2002). The ultimate impact on the survival of the species is dependent on many factors: · the reproductive biology of the species, such as mode of regeneration, time it takes to reach maturity and the type, size and longevity of seed banks; · the level of mortality in the population; and · the relationship between regeneration events (e.g. fire) and disease events (DPIWE, 2003e). Management responses The Regional Forest Agreement (RFA) improved the reservation of many forest vegetation communities in Tasmania. The reservation of a number of rainforest community types has been improved, namely the King Billy Pine, Huon Pine, Pencil Pine, Callidendrous and Thamnic rainforest communities (RPDC 2002). According to Tasmania's Nature Conservation Strategy, 46.4% of Tasmania's rainforest communities are contained within reserves, with 88% of the communities being well reserved (State Biodiversity Committee 2002). Research into ecology and fire management has indicated that there needs to be clear objectives and a targeted use of fire in natural ecosystems. In many cases the exclusion of fire is not desirable or feasible. The fire management strategies currently in place seek to use an integrated mixture of ecosystem-management burning, strategic hazard-reduction burning and, where appropriate, fire suppression (DPIWE 2003). Appropriate fire management in neighbouring vegetation communities is very important for the protection of temperate rainforest, as these communities often border highly flammable vegetation such as buttongrass moorlands and sclerophyll forest. Marsupial Stronghold Tasmania is the final refuge for a long list of species that have recently succumbed to pressures of human impacts and introduced species on mainland Australia. Tasmania retains the most ecologically diverse group of large marsupial carnivores in Australia, namely the Eastern Quoll (Dasyurus viverrinus), the Spotted-tail Quoll (D. maculatus) and the Tasmanian Devil (Sarcophilus harrisii). Several of the marsupial species that are now extinct or very restricted on the mainland still maintain viable populations in Tasmania, namely the Eastern Barred Bandicoot (Perameles gunnii gunnii), Tasmanian Bettong (Bettongia gaimardi) and the Tasmanian Pademelon (Thylogale billardierii). Threats Until recently, Tasmania has been free of large introduced carnivorous predators. Past attempts to introduce the fox have failed primarily due to low import numbers and predation by native carnivores such as the Tasmanian Devil. In 2000, an estimated 12-20 foxes were deliberately introduced into Tasmania and, according to reports and sightings, have increased in distribution and numbers (DPIWE 2002). The Red Fox (Vulpes vulpes) is recognised as the single most devastating introduced pest and threat to Australia's native land fauna. It is listed as a National Threat in the Environment Protection and Biodiversity Conservation Act 1999 Should the fox become established in Tasmania, 78 native vertebrate species would be at risk. Of these, 34 species have locally restricted ranges, 16 are suspected to be already declining in distribution and 12 are listed as threatened in Commonwealth and State threatened species legislation (DPIWE 2002). The young of many native animals are highly vulnerable to fox predation, and the adults may suffer intense competition for food. Due to their wide diet, foxes compete with many animals, such as Tasmanian Devils, quolls, raptors and ravens. The maintenance of healthy populations of these native animals can help to defend against the fox. Another threat has also hit the State's most recognisable marsupial, the Tasmanian Devil. A virus causing cancerous lesions on the face, a softening of the skull and eventual death has the potential to reach epidemic levels and devastate a large proportion of the devil's population. The disease was first noticed in the mid-1990s but has become more prevalent, being recorded through the east, north east, south east, midlands and the edges of the highlands (DPIWE 2003). Like many infectious diseases it appears to be density-dependent in that it kills more than 90% of adults in high-density areas and 40-50% in medium-low density areas (DPIWE 2003). Its overall impact is quite chequered across the State and it does not seem to affect other species. The current disease is not expected to lead to extinction. However, there is a concern that if the population is diminished and an introduced predator, such as the fox, replaces it in the food chain it may be difficult for Tasmanian Devil populations to recover to their normal size and distribution. A serious epidemic affected the devil in the 1920s, but the species was able to recover successfully in the absence other predators such as the fox (DPIWE 2003). It is also believed that Tasmanian Devils may be acting as a buffer to the establishment of foxes in Tasmania through competition for food. If devil numbers were to significantly decrease it just may create the window of opportunity needed for the fox to become established in the State. Management Responses The State Government is actively undertaking actions to manage both of these threats. The Tasmanian Government has established a Fox Free Taskforce to implement a long-term eradication program and to ensure foxes are never introduced in Tasmania again, and have so far allocated $40,000 for the study of the Tasmanian Devil virus and to identify its cause. A range of methods to eradicate the fox are currently underway and others are being trialed (DPIWE 2002): Cave Fauna Tasmanian cave fauna is amongst the most species rich, abundant and prevalent in temperate Australia (DPIWE 2001). More than 150 species of invertebrates have been identified from caves in Tasmania. However, the total populations in some caves are very small, some restricted to a few individuals in a single cave (DPIWE 2001). Cave-dwelling invertebrates are highly adapted to cave environments as they often have reduced colouring and eyes and well-developed organs sensitive to touch. The twilight zone of caves are occupied by a high diversity of animal, including the Giant Cave Spider (Hickmania troglodytes), various cave crickets (Micropathus spp. ), the Tasmanian Glow Worm (Arachnocampa tasmaniensis) and carabid beetles (Goedetrechus, Tasmanotrechus and Idacarabus spp. ). In contrast to caves on the mainland, there are no known bat colonies in Tasmanian caves. Some of the more important cave sites with specialised fauna include Mystery Creek, Mole Creek, Ida Bay, Redpa and Sherrills Cave. The Mole Creek karst system has three invertebrates that are endemic to the area, with all three listed under the Threatened Species Protection Act 1995. These include a highly modified cave beetle, Cockerills Cave Beetle (Tasmanotrechus cockerilli), a cave harvestman (Hickmanoxyomma gibbergunyar) and an extremely rare cave false scorpion (Pseudotyrannochthonius typhlus).
Threats Threatening processes can operate both above and below the ground in karst systems. Natural processes in karst systems are controlled by flows of water and air, along with what is dissolved and transported into them (DPIWE 2001). The impacts on karst systems can be separated in hydrological, atmospheric and visitor impacts (DPIWE 2001). Hydrologial Impacts. The hydrological systems of caves are composed of surface and underground streams and seepage from water flowing through the soils and rocks. The surface and groundwater qualities are particularly important to the cave environment and are often affected by upstream land use practices, particularly if the catchment includes agricultural land or land used for forestry. Atmospheric Impacts. Cave microclimates are easily affected by inappropriate development such as: Visitor Impacts. Visitor impacts are varied and depend on the number of people involved and the sensitivity of the cave system. Show caves are some of the most highly impacted as the infrastructure developments allow for mass visitation. Undeveloped caves receive fewer visitors but are prone to the effects of careless recreational users. Undeveloped caves are not effectively monitored and are prone to vandalism and the erosion of surface and underground tracks. Management Responses The Mole Creek Karst National Park Draft Management Plan was completed in 2001 and establishes objectives, policies and actions for the conservation of cave fauna. These include: |
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Threatened Ecological Communities - at a glance
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Based on the review of the threats and management responses relating to the special biodiversity features, it appears the following should be considered for future management and protection: Tasmania Together and the RMPS Relevant Tasmania Together goals and standards for 'Biodiversity' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together. Involvement of the community, and the fair and orderly use of resources are also fundamental principles of the RMPS. The RMPS objectives have been developed to advance the principles of sustainable development. |
