Biodiversity Surveys

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Biodiversity Survey in the Minnow Catchment

This project was undertaken as a component of the Community Environments Program grant. The project aimed to identify species within the Minnow Catchment in North-western Tasmania. Over 35 hectares of land was surveyed across remnant natural forest, plantation verges, and riparian buffer zones. Bird, macroinvertebrate, and fungi surveys were also undertaken. Fungi surveys were dependent on climatic conditions and were not possible at many of the sites. Surveys were undertaken between July 2020 and May 2021.

The Minnow Catchment is home to a diverse range of vegetation species, threatened forest communities, and endangered faunal species. Maintaining, protecting, and potentially expanding the small remnant stands should be a major focus of activities in the catchment. Current risks are mainly from private landholders who are removing native stands of trees from their properties. It is unknown what these particular communities were, and now harvested, they have reduced the available corridor and ‘island’ of vegetation for native species.

Location

The Minnow Catchment is located in north-west Tasmania and is a sub-catchment of the 1740 km² Mersey River system which flows from the Central Highlands through to Bass Strait at Devonport. The headwaters of the Minnow River is located on the top of Mount Roland, in the Fossey Mountain Range, at an altitude of 1080 m, and is joined by two tributaries before reaching the four stage falls on the eastern face. 

Biodiversity Sites Map

Site 1- The forest type at this site is not one that is currently listed by TASVEG, due to the unusual dominance of Pomaderris apetala. The area would seem to be a transitional forest community between wet sclerophyll forest and rainforest. Further surveys of both banks will be required to make an assessment which will not be possible until river levels are lower, enabling safe access to undertake the surveys.

Site 2 – to identify the ecoclines present it would require an area greater than 4 hectares to be surveyed. The area is difficult to access and would require an extensive period of time to undertake such a survey. It would be of value to undertake the survey, as the diverse species present could be part of unusual community assemblages. The area is also at risk of potential logging, therefore understanding the communities present at this site would be important if protection of the site is to be achieved.

Site 3 – Biodiversity is good at this site, and water quality is good. While the spread of Radiata pine wildlings is impacting on the site, and weed species are greater than the upstream sites, the area is providing habitat for a number of species. Removal of the wildlings from the banks of the river would facilitate a great improvement in habitat condition.

Site 4 – This site is diverse in vegetation species, though weeds will continue to impact on the site, particularly the spread of foxgloves. A survey of all the vegetation along this tributary would be advantageous, as it could support a previously undescribed vegetation community. It would be important to undertake this survey, so that protection could be afforded the area when harvesting of the Radiata pine plantation is undertaken.

Site 5 – The site is an important area of Eucalyptus viminalis wet forest which is listed as a Threatened forest community under the Nature Conservation Act 2002. The site is providing essential habitat for at least one endangered species, Astacopsis gouldi.

Site 6 – The site is an important riparian natural forest area, that provides essential habitat for the endangered Giant freshwater crayfish and the Spotted-tail quoll. The community is in good condition. Protection from recreational riders/drivers may be required.

Site 7 – This is an important site for wildlife corridor which links to the reserved area on Lizard Hill. The area would benefit from additional corridors through private land and along riparian areas managed by Forico.

Site 8 – The site forms part of an important network of riparian buffers within the catchment, particularly due to the presence of the Giant freshwater crayfish. The area has been impacted by recreational activities, which Forico have attempted to mitigate by preventing access to the river. Further work at this site could include fencing of the zone, and planting more native vegetation to enhance and strengthen the southern access to the site.

Site 9 – The site is an important corridor for native endangered fauna. Further surveying and monitoring of the site is recommended. The site is grazed by sheep which is having some negative impacts. The diversity of bird species is greatest here, probably due to the mix of forest, rural land, and semi-wetland, which is accepted as prime habitat.

Site 10 – The site is an important corridor for native species, and would benefit from some enhancement ie size increase and vegetation planting. The site is also frequently visited by feral cats which pose a risk to faunal diversity in the area.

Site 11- This site is also an important corridor. It is very sparsely vegetated and could benefit from an increase in size to facilitate a permanent corridor for native species.

Site 12 – The site is the top of a hill and is an ‘island’ of native vegetation amidst plantation, which is visited by endangered fauna. Establishing some connective native vegetation to the site would provide important corridors for these endangered fauna. Further surveys at the site would aid in accurately identifying the eastern section of vegetation community.

Site 13 – This site is another important corridor for native species, which links to a network of riparian buffers in the area. Increased native vegetation could be planted to connect smaller tributaries to this site.

Site 14 - Planting a diverse range of species at this site, and along the small tributaries would improve the location and provide corridors for native fauna. The main tributary is choked with willows, which if removed and re-vegetated, would improve the general habitat in this area.

Site 15- This is an important and healthy are of native forest, which could potentially be impacted by harvesting activities. Protecting of this site would maintain water quality in the Minnow which receives run-off from the site. Further evaluation is required to confirm the forest community at this site.

Site 16 – The remnant vegetation at this site is in condition, and has a high diversity of species, which may have been assisted by the bushfire adjacent to the site. If the area is to continue to rehabilitate it will provide important are for native fauna.

Overall

A total of 64 bird species have been observed in the Minnow Catchment, of which 5 were introduced species. House sparrow, starlings, and Blackbirds were mainly observed close to rural properties with houses nearby. European goldfinches were observed in large flocks near either rural properties or harvested plantation areas. Kookaburras were observed across the whole catchment, apart from the headwater area of the Minnow River.

Three bird species present are endangered:

  • Accipiter novaehollandiae -Grey goshawk –White morphology
  • Aquilla audax fleayi- Tasmanian wedge-tailed eagle
  • Tyto novaehollandiae castanops -Tasmanian Masked owl

And three species are vulnerable:

  • Haliaeetus leucogaster - White-bellied sea eagle
  • Haliastur sphenurus – Whistling kite
  • Hirundapus caudacutus – White-throated needletail

Other endangered fauna in the catchment include

  • Dasyurus maculatus (Spotted-tail quoll),
  • Sarcophilus harrisii (Tasmanian devil), and
  • Astacopsis gouldi (Giant freshwater crayfish).

34 weed species were observed across the study sites, which is approximately one third of the known species in the catchment.

Download the full report Biodiversity Report by Barbara Alsop (2021) [download size 5MB]

See also Biodiversity Surveys in the Minnow Catchment Sarah Lloyd (2017)