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Australasian Plant Conservation

Originally published in Australasian Plant Conservation 16(3), December 2007- February 2008

Introducing ‘Conservation and management of Buttongrass moorland’

Jayne Balmer
Department of Primary Industries and Water, Hobart, Tas. Email: jayne.balmer@dpiw.tas.gov.au

Buttongrass moorlands were the focus of a workshop held in Hobart in July 2007, and several presentations are included in this issue. The taxon that most characterises Buttongrass moorland is the tussock sedge Gymnoschoenus sphaerocephalus (Buttongrass). The genus Gymnoschoenus is endemic to Australia and has only two species, Gymnoschoenus sphaerocephalus and G. anceps. The first species has its greatest abundance in Tasmania, but is distributed widely in nutrient-poor, cool temperate, wet and poorly drained sites along the coastal and upland regions of eastern Australia as far north as southern Queensland. It also has a very restricted distribution in the southeast of South Australia, where it is listed as endangered. The other species, G. anceps, is restricted to the southwest coastal region of West Australia, where it also occurs in swamps and seasonally wet flats.

The extensive dominance by Gymnoschoenus of Tasmania’s sedgelands and wet heaths has led to this ecosystem being dubbed ‘Buttongrass moorlands’ in Tasmania. Elsewhere in Australia analogous vegetation may be referred to as bog, swamp, sedgeland or wet heath. An example of analogous vegetation in New South Wales that includes Buttongrass moorland in its range of variation is the nationally listed community ‘Temperate highland peat swamps on sandstone’ (Environment Protection and Biodiversity Conservation Act 1999).

This issue of Australasian Plant Conservation focuses on studies of Tasmanian Buttongrass moorlands. The opening article by Sib Corbett and Jayne Balmer describes the variation in structure and floristics of Buttongrass moorlands in Tasmania and how these have been partitioned into mapping classes for the state-wide 1:25,000 vegetation map ‘TASVEG’. The article provides detailed ecological descriptions of the major mapping classes used for the western Tasmanian Blanket Moors.

In relation to reservation of Buttongrass Moorland, an analysis of TASVEG 1.0 mapping (TVMMP 2005) shows that within Tasmania more than 89% of this ecosystem is reserved. Mapping of Buttongrass into detailed mapping categories has been almost completed for the West, Central Highlands and the Southern Ranges Bioregions where Buttongrass moorlands are extensive and all classes are well reserved. Mapping of Buttongrass moorlands in other nationally recognised bioregions (IBRA) has not yet distinguished the vegetation into detailed mapping units. The percentage of Buttongrass moorlands reserved exceeds 40% for all bioregions in which it occurs. However the Flinders and South East bioregion have less than 200 ha each while the King Bioregion may have rare floristic types associated with the rare occurrence of Buttongrass moorland on rich alluvial soils on basalt (Jarman et al. 1988). More detailed mapping is therefore still required to ensure that Comprehensive and Adequate Reservation has been achieved in all Tasmanian bioregions (Gilfedder et al. 2007).

David Bowman provides an intriguing comparison of the ecosystem dynamics in southwest Tasmania (where highly flammable Buttongrass moorland is extensively juxtaposed with fire sensitive forest) with the vegetation mosaics of Spinifex hummock grasslands and Mulga shrubland in central Australia. He demonstrates that the boundaries within these mosaics in Central Australia are essentially held in place by differences in soil nutrients that have resulted from differences in fire history. Climate change has the potential to alter fire frequencies significantly, which may destabilise the vegetation boundaries, altering vegetation and soils.

Karen King used simulation modelling to determine the likely outcomes of altering patterns of prescribed management burning in Buttongrass moorlands in terms of reducing the impacts of wildfires on life, property and biodiversity values. Her modelling suggests that 10% of the extent of Buttongrass moorlands will need to be burnt annually to significantly reduce the frequency and size of wildfire events and to lower the probability of burning fire sensitive vegetation and other assets. Current annual management burns within Buttongrass moorland in southwest Tasmania fall far short of the optimum extent of burning proposed by the modelling.

Aspects of the flora of Buttongrass moorlands are described in several articles in this issue. Naomi Lawrence and her co-authors describe the floristic values contained within this ecosystem providing examples of restricted endemics, primitive taxa and rare and threatened flora. They also briefly document the characteristics of the flora that make it one of the most flammable vegetation types in the world. Scleromorphic graminoids with high silica contents and leaf surface to volume ratios have resulted in long term retention of dead leaves within the plant which are resistant to decay. The consequence is an aerial fuel array that dries quickly allowing this vegetation to burn following one day without rain (Marsden-Smedley and Catchpole 1995).

James Wood and Micah Visoiu describe the preliminary results of seed collection within Buttongrass moorlands undertaken as part of the global ‘SeedSafe’ project. They found that a number of species have very poor seed viability and suggest that fire may be needed to stimulate seed production in some species. Jennie Whinam describes the short term impacts of fires within Buttongrass moorlands on remnant Sphagnum peatland communities, demonstrating that single fire events can reduce Sphagnum from nearly ubiquitous to only a minor presence. Relationships between fire and other bryophyte species are described by Mikayla Jones in her account of the bryophyte communities of Buttongrass moorlands. Gintaras Kantvilas continues the theme of non-vascular species, describing the lichens of Buttongrass moorlands in Tasmania and the various specific habitats they occupy. Kantvilas points out that it is important when managing Buttongrass moorlands to appreciate the lichen diversity and understand these habitats.

An overview of the fauna and its ecology, including both vertebrates and invertebrates, is provided by Michael Driessen. His article is followed by a detailed account of one of the keystone fauna within Buttongrass moorlands, the Burrowing Crayfish, by Alastair Richardson and Neil Doran. The burrows of these invertebrates provide a ventilation system within the otherwise anaerobic soils when they are fully saturated, considerably enhancing plant growth. Another group of soil dwellers are the soil mites. David Green reveals the richness and diversity of these fauna within Buttongrass moorland and discusses the relationship between the mite communities and vegetation age. Peter Tyler describes the limnology of Tasmania’s waters, including the characteristics that set those of southwest of Tasmania apart from the rest. In the southwest, extensive distribution of organic soils results in tannin-stained waters, which provide a distinctive environment for rare and endemic algae and other micro-organisms.

The major threat to Buttongrass moorlands of Tasmania, apart from climate change, is that posed by the plant pathogen Phytophthora cinnamomi (Root Rot). The serious nature of this threat is described by Rudman and Balmer. One of the ways in which this disease is spread is by the movement of infected soil on bushwalker’s boots. There is also a high risk of spread with track work and maintenance operations, which involve helicopter transport of digging equipment and track materials. Grant Dixon describes other impacts of recreational walkers in the final article of the bulletin.

Bush walkers have some of the greatest impacts directly and indirectly on Buttongrass moorlands, but it is not clear that they gain much pleasure from travelling across boggy Buttongrass plains. In fact, this vegetation is probably the least appreciated and valued in Tasmania. Grant (2007) demonstrated that the most common words people use in recounting experiences of Buttongrass are “hated, useless, wretched, monotonous, drab-coloured, insecure, exasperating, hazardous, sour, waste.” Yet the Buttongrass moorlands of the Tasmanian Wilderness World Heritage Area are beautiful, diverse and contain values that meet all four natural criteria for World Heritage Listing (Balmer et al. 2004).

The Buttongrass moorland management workshop was held as one of a number of events to celebrate the 25th anniversary of the inscription of the Tasmanian Wilderness upon the UNESCO World Heritage list. As part of the workshop and these celebrations, a small nature writing prize was offered for the best prose and poetry entries inspired by Buttongrass. The winning poetry entry ‘Buttongrass’ by Adrienne Eberhard (p 17) is a beautiful piece of poetry that one of the judges Gina Mercer noted ‘resonates with understated meaning long after you have finished reading it.’ The prose entry ‘A carnivore in fairy’s clothing’ by Janet Fenton (p 5) enchants and delights the reader whilst providing a clear and vivid account of some fascinating plant species within Buttongrass moorland. The importance of story in developing a love for and appreciation of the natural world cannot be underestimated and it is hoped that these works will inspire further positive accounts of this most fascinating ecosystem.

References

Balmer, J., Whinam. J., Kelman, J. Kirkpatrick, J.B. and Lazarus, E. (2004) A review of the floristic values of the Tasmanian Wilderness World Heritage Area. Nature Conservation Report 2004/3. Department of Primary Industries, Water and Environment, Hobart.

Gilfedder, L., Faulkner, F. and Balmer, J. (2007) How well reserved are Tasmania’s Buttongrass moorland communities? Poster Paper presented at the Buttongrass Moorland Management Workshop, 4-6 July, School of Geography and Environmental Studies, University of Tasmania, Hobart.

Grant, P. (2007) ‘From one quaking tussock to the next: walkers and Buttongrass’. Unpublished manuscript presented at the Buttongrass moorland management workshop, University of Tasmania, Hobart, July 2007, Tasmanian Parks and Wildlife Service.

Jarman, S.J., Kantvilas, G. and Brown, M.J. (1988) Buttongrass moorland in Tasmania. Research Report No. 2, Tasmanian Forest Research Council Inc.

Marsden-Smedley, J.B. and Catchpole, W.R. (1995) Fire behaviour modelling in Tasmanian Buttongrass moorlands. I. Fuel Characteristics. International Journal of Wildland Fire 5: 203-214.

Tasmanian Vegetation Mapping and Monitoring Program (TVMMP) (2005) TASVEG version 1.0, Tasmanian Vegetation Map 1:25,000. Department of Primary Industries, Water and Environment, Hobart.

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