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[1] " Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)13 April 2005  1. Scientific name, common name (where appropriate), major taxon group  Boronia gunnii (Gunn's Boronia)  A review of the Boronia group in eastern and northern Australia was undertaken in 2003 (Duretto 2003). Prior to this review, six species of Boronia were recognised in Tasmania (i.e. B. anemonifolia, B. citriodora, B. nana, B. parviflora, B. pilosa, and B. rhomboidea). The 2003 revision identified a total of fifteen taxa for Tasmania with nine endemics, including Boronia gunnii. Following this revision, surveys were commissioned to verify both the distribution and the population parameters of a number of Boronia species, including Boronia gunnii. These surveys were undertaken during August to December 2003. Numbers of mature plants were determined either through direct counts or by estimates of plant density and areas of occupancy.  2. Description  Gunn's Boronia is an erect woody shrub to 1.2m high that is endemic to Tasmania, occurring in two populations in Tasmania's Eastern Tiers along three stretches of river: the upper St Paul's River and Dukes River and the lower reaches of the Apsley River. The species is considered to be strictly riparian in habitat, occurring in the flood zone of these rivers in rock crevices or in the shelter of boulders. Associated shrubby species include Micranthum hexandrum, Hakea macrocarpa, Acacia mucronata, Spyridium obovatum, Leptospermum lanigerum and Epacris exserta. Gunn's Boronia is known only to occur on the base substrate known as 'Jurassic dolerite'.  3. National context  Gunn's Boronia only occurs in Tasmania and is known from two populations. One population occurs at Apsley River and the other at St Pauls and Dukes Rivers. A third population was known from the lower Esk River but has not been recorded since the early 1960s and is now considered to be extinct. Approximately two thirds of the mature individuals of Gunn's Boronia occur in the Mt Puzzler Forest Reserve and the Douglas-Apsley National Park. The remaining third occurs within an informal streamside reserve on State Forest land.  Gunn's Boronia has been nominated for listing as a threatened species under the Tasmanian Threatened Species Protection Act 1995. The Tasmanian Threatened Species Scientific Advisory Committee has made a final recommendation to list this species.  EPBC Act criteria.  TSSC judges the species to be eligible for listing as vulnerable under the EPBC Act. The justification against the criteria is as follows:  Criterion 1 - It has undergone, is suspected to have undergone or is likely to undergo in the immediate future a very severe, severe or substantial reduction in numbers.  In addition to the two currently known populations, there are historical records of Gunn's Boronia from the lower South Esk River near Launceston. During the 1960s, Gunn's Boronia was known as the Cataract Gorge Boronia as this location along the South Esk River was the species' only known location at the time. Construction of the Trevallyn Dam in the 1950s and subsequent changes to the natural flow of the lower South Esk River, including possible impacts from the earlier Duck Reach power station, are believed to have contributed to the loss of this population. The Reedy Basin site, Cataract Gorge, has been flooded and the species habitat downstream at 2nd Basin and Cataract Gorge invaded by exotic weeds (e.g. gorse and willow). Recent surveys have failed to locate the species at these locations and the South Esk River population is now considered to be extinct. The loss of Gunn's Boronia from the South Esk River has meant a reduction in the species' range (linear extent) of the species from 102 km to 17 km.  A specimen of Gunn's Boronia was purportedly collected from the Denison Rivulet area in the 1980s. Targeted surveys have failed however to locate this or any other populations. The known range of the species has substantially reduced since the 1960s, with one of three populations being lost since this time. A population size reduction is inferred but there is a lack of quantitative data to estimate the actual reduction in numbers that has occurred.  The species' habitat is potentially impacted on by upstream activities. This includes activities that increase runoff and sediment loads; permanent flooding and invasion from exotic weeds. However, there are no known impacts from these potential threats at this stage. The actual susceptibility of Gunn's Boronia to the plant pathogen Phytophthora cinnamomi is unknown. It is noted however that the susceptibility of other Boronia species to Phytophthora cinnamomi has long been recognised. Fire, or frequent fires, can create conditions conducive to an increased abundance and spread of Phytophthora cinnamomi. Fire reduces organic matter in the soil and associated soil micro-flora/fauna that can have a suppressive effect on Phytophthora cinnamomi. Fire also reduces the vegetation cover and allows soil temperature and water availability to rise, facilitating an increase in the pathogen. The movement of fire fighters and associated machinery is a secondary mechanism aiding the spread of Phytophthora cinnamomi. Too frequent fire is considered to be detrimental to the survival of the species. Conversely, should long periods occur between suitable fire events, plants may become senescent with soil-stored seed becoming unviable.  While Gunn's Boronia is suspected to have undergone a reduction in numbers, there is insufficient data to quantify the degree of decline and insufficient evidence to indicate that the species is likely to undergo a reduction in numbers in the immediate future. Therefore, the species is not eligible for listing under this criterion.  Criterion 2 - Its geographic distribution is precarious for the survival of the species and is very restricted, restricted or limited.  It is estimated that the population of Gunn's Boronia has an extent of occurrence of 29 km² and an area of occupancy of between 3-5 hectares. Two populations of Gunn's Boronia are currently known. They occur at St Pauls and Dukes Rivers (approximately 500-600 plants along a 5 km stretch of river) and at Apsley River (approximately 250-300 plants along a 3 km stretch of river). A third population was known from the lower South Esk River. Recent surveys have failed to locate this population and it is now considered to be extinct.  While the species has a restricted geographic distribution, and is known from only two populations, there is insufficient evidence to indicate that this geographic distribution is, in itself, precarious for the survival of the species. The species' habitat may potentially be impacted on by upstream activities, including activities that increase runoff and sediment loads; permanent flooding and invasion from exotic weeds (e.g. gorse and willow). However, there are no known impacts from these potential threats at this stage. The actual susceptibility of Gunn's Boronia to the plant pathogen Phytophthora cinnamomi is unknown. Fire, or frequent fires, can create conditions conducive to an increased abundance and spread of Phytophthora cinnamomi. Fire reduces organic matter in the soil and associated soil micro-flora/fauna that can have a suppressive effect on Phytophthora cinnamomi. Fire also reduces the vegetation cover and allows soil temperature and water availability to rise, facilitating an increase in the pathogen. The movement of fire fighters and associated machinery is a secondary mechanism aiding the spread of Phytophthora cinnamomi. Too frequent fire is considered to be detrimental to the survival of the species. Conversely, should long periods occur between suitable fire events, plants may become senescent with soil-stored seed becoming unviable.  There is insufficient evidence to indicate that the existing population of Gunn's Boronia is subject to a continuing decline or extreme fluctuations in population numbers. It is noted that approximately two thirds of the total mature population occurs in reserved areas and is unlikely to be subject to catastrophic disturbance.  The geographic distribution, while restricted, is not considered precarious for the survival of the species as the species is well protected in reserves, is under no immediate threat and appears not to be subject to an ongoing decline. Therefore, the species is not eligible for listing under this criterion.  Criterion 3 - The estimated total number of mature individuals is very low, low, or limited, and: (a) evidence suggests that the number will continue to decline at a very high, high, or substantial rate; or (b) the number is likely to continue to decline and its geographic distribution is precarious for its survival.  The number of mature individuals of Gunn's Boronia is estimated to be low, approximately 750-900, occurring in two populations along St Pauls and Dukes Rivers and at Apsley River. There is insufficient evidence to indicate a continuing decline or any evidence that extreme population fluctuations occur. In addition, no subpopulation is estimated to contain a significant proportion of the mature population. There is a lack of evidence that the number of mature individuals will continue to decline at a significant rate, or as noted under criterion 2, that the geographic distribution, in itself, is precarious for the survival of the species.  There is insufficient quantitative data available against this criterion. Therefore, the species is not eligible for listing under this criterion.  Criterion 4 - The estimated total number of mature individuals is extremely low, very low or low.  The number of mature individuals is low. The total population of Gunn's Boronia is estimated to be approximately between 750-900 mature individuals. In addition, this population is restricted, with an estimated area of occupancy between 3-5 hectares. Gunn's Boronia is only known to occur in two populations, one along the St Pauls and Dukes Rivers and the other along the Apsley River. In total, the species is known from two stretches of river habitat (5 km and 3 km respectively) along these rivers.  The estimated total number of mature individuals is low. The species is currently restricted to two populations within an 8 km stretch of river habitat in Tasmania's Eastern Tiers region. Therefore, the species is eligible for listing as vulnerable under this criterion.  Criterion 5 - Probability of extinction in the wild  There is no quantitative data available against this criterion. Therefore, the species is not eligible for listing under this criterion.  5. Conclusion  Gunn's Boronia has an estimated total population of between 750-900 mature individuals. It is known to have a restricted distribution, occurring in two populations along three rivers in Tasmania's Eastern Tiers region. Potential threats to the species include the impact of the plant pathogen Phytophthora cinnamomi, an inappropriate fire regime, permanent flooding of its habitat and the invasion of its habitat by exotic weed species. The species is eligible for listing as vulnerable under criterion 4.  6. Recommendation  TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by including in the list in the vulnerable category:  Boronia gunnii (Gunn's Boronia) Conservation Advice  Gunn's Boronia is a woody shrub that grows to 1.2 m in height. It occurs only in two populations in Tasmania's Eastern Tiers region along three rivers: the upper St Pauls River and Dukes River and the lower reaches of the Apsley River (North Tasmania NRM region). It is a riparian species, occurring in the flood zones of these rivers in rock crevices or in the shelter of boulders.  Gunn's Boronia occurs in Mt Puzzler Forest Reserve, the Douglas-Apsley National Park, and on State Forest Land.  Key threats to Gunn's Boronia include: potential impacts from the plant pathogen Phytophthora cinnamomi, an inappropriate fire regime, permanent flooding of its habitat, increasing runoff and sediment loads from upstream activities, and invasion and encroachment by exotic weed species.  The priority recovery and threat abatement actions required for this species are:  protection from upslope and upstream activities (e.g. permanent flooding, runoff and increasing sediment loads) \tcontrol weeds at known sites of the species and minimise activities that promote weed invasion; \tinvestigation, development and implemention of an appropriate fire management regime for sites where the species is known to occur; and \tincorporation of habitat areas within a new Phytophthora cinnamomi Management Area and adoption of protocols to minimise the introduction and spread of the pathogen to sites where the species occurs. This list does not encompass all actions that may be of benefit to this species, but highlights those that are considered to be of the highest priority at the time of listing.  A Recovery Plan is not yet in place for this species. A national Threat Abatement Plan exists for the plant pathogen Phytophthora cinnamomi: 'Threatened Abatement Plan for Dieback Caused by the Root-rot Fungus Phytophthora cinnamomi, Commonwealth of Australia 2001.'  Priority for the development of recovery plan: Low.  Publications used to assess the nomination  Duretto, M.F. (2003) Notes on Boronia (Rutaceae) in eastern and northern Australia. Muelleria 17, 19-135.  Schahinger, R. (2004) Distribution and Conservation Status of the Tasmanian Endemic Shrubs Boronia gunnii, Boronia hemichiton and Boronia hippopala. Report to the Threatened Species Unit, Department of Primary Industries, Water and Environment, Hobart, Tasmania."