Project 03A: ACTewAGL/ACT National Parks 2003-

 




State of the mountain mires of the Australian Capital Territory after fires 14-22 January 2003

Researchers: Prof. Geoff Hope, Dr Alan Wade and Dr Jennie Whinam

Summary: The mountains of the ACT support substantial areas of mires in interfluves and valley heads, as well as areas of boggy riparian vegetation along streams. They include valley fill deposits with sedge fens at lower altitudes (800-1000m), shrubby Sphagnum cristatum –epacrid shrub bogs in the subalpine and wet tussock grasslands. Almost all the montane mires in the ACT have been affected by the January 2003 fires with the burnt area varying from 55-100% of the mire surface. Surveys of major wetland areas have been carried out by field visits from vehicles or helicopter and some aerial inspection.

In general the vegetation in the burnt swamp areas has been reduced to ash or charred remnants with the exception of Sphagnum moss hummocks, which have partly remained although the moss has mostly been killed. However the fibrous root mat has mostly survived as the peat soils have not caught fire except in a isolated patches. Some regeneration of sedges, grasses and other monocots is taking place. Shrubs have mostly been killed except for resprouting of some myrtaceous species.

The mires so far visited will recover, but at a slow rate. A shift towards sedge and grass dominance will increase runoff during showers, which may increase stream incision. Peat growth (organic matter accumulation) may be negative due to more exposure and better aeration of the peat, which will also provide a habitat for wind-borne weeds such as thistles. The 2003 fires will accelerate the trend towards loss of shrub-moss bog that probably commenced when the mires were disturbed by cattle grazing and pastoral fires in the late 19th century. Research is being undertaken to assess the extent of the loss. Some simple remedial measures to encourage regrowth on the remnant dead Sphagnum hummocks might be helpful, and consideration should be given to returning the hydrology to pre-fire state.

Mire Histories
Current research based on carbon dating, fossil pollen and spores, and microscopic charcoal suggests that the mires of the ACT post-date the last period of glaciation which occurred from 26-16,000 years ago (Barrows et al 2001) and owe their origin to the post-glacial amelioration of climatic conditions. At the end of the Pleistocene most montane streams lay above the treeline and their channels had been infilled by sands and gravels. Increasing temperature and precipitation around 12-9000 years ago allowed subalpine plants to stabilise the catchments permitting the establishment of many swamp plants on the river flats. The plants blocked streams and the wet conditions initiated peat accumulation. However there is no clear correlation between the basal dates and mire altitude. The oldest sites, Nursery and Cotter Source, lie in very different settings (Table 1).

Table 1. Dates for the Initiation of Peat Formation in ACT and nearby NSW Montane Site
Site Name, Locality

Altitude
(m)
Date
(years BP)
Peat
(cm)
Source

Cotter Source A, Mt Scabby, ACT
1720
9040± 80
115
Hope unpubl.
Ginini Bog, Mt Ginini, ACT
1590
3,280±70
85
Costin unpubl
Micalong Swamp, 35 km E Tumut
1100
12,330±250
390
Kemp (1993)
Mulloon Swamp, 25km W of Braidwood
799
3440 ± 90
345
Hope, unpubl
Nursery Swamp, 40km SW Canberra, ACT
1100
8,200±250
298
Hope unpubl.
Rotten Swamp, NE of Mt Kelly, ACT
1445
5,500±90
60
Clark 1986
Snowy Flat, Mt Gingera, ACT
1618
7,130 ± 70
205
Macphail, unpubl
Yaouk Swamp, Scabby Nature Reserve
1100
9250 ± 40
195
Keany, unpubl

The reasons for the variation in ages for the initiation of peat are not yet understood. The younger sites (Rotten Swamp and Ginini Bog) have probably lost earlier peat fills, possibly by fire. Yaouk Swamp, and possibly Snowy Flat, have basal peaty clays that are early Holocene, but seem to lack sediments from the last few thousand years. A suggestion is that since wet sclerophyll forest expanded in the mid-Holocene to altitudes beyond present limits, wetter conditions than present may have occurred from 9000 to about 4000 years BP. This may have been a time of consistent peat formation. Perhaps some peatlands did not grow well after 4000 years ago or there have been erosional events since that time. Only Cotter Source Bog possibly provides a fairly complete record of the Holocene.

References

Ashton, D. H. and Hargreaves, G. R. 1993. Dynamics of subalpine vegetation at Echo Flat, Lake Mountain, Victoria. Australian Journal of Ecology 12, 35-60.

Australian Nature Conservation Agency 1996. A Directory of Important Wetlands in Australia. Canberra, Australian Nature Conservation Agency, 2nd ed.

Barrows, T. T., Stone, J. O., Fifield, L. K. and Creswell, R. G. 2001. Late Pleistocene glaciation of the Kosciuszko Massif, Snowy Mountains, Australia. Quat. Research 55, 179-189.

Clark, R. L. 1980 Sphagnum growth on Ginini Flats, A. C. T. Unpubl. Reprt to NSW National Parks and Wildlife Service.

Clark, R. L. 1983. Fire History from Fossil Charcoal in Lake and Swamp Sediments, Ph. D. Thesis, Canberra, Australian National University.

Clark, R. L. 1986. The fire history of Rotten Swamp, A.C.T., Canberra, Unpublished Report to ACT Parks and Conservation Service, CSIRO, Canberra.

Clarke, P. J. and Martin, A. R. H. 1999. Sphagnum peatlands of Kosciuszko National Park in relation to altitude, time and disturbance. Aust. J. Botany 47, 519-536.

Costin, A. B. 1954. A Study of the Ecosystems of the Monaro Region of New South Wales with Special Reference to Soil Erosion, Sydney, Government Printer.

Costin, A. B. 1972. Carbon-14 dates from the Snowy Mountains area, southeastern Australia, and their interpretation, Quaternary Research 2, 579-590.

Costin A. B, Gray, M., Totterdell, C. J. and Wimbush, D. J. 1979. Kosciusko Alpine Flora. Melbourne, CSIRO/Collins.

Dodson, J. R., De Salis, T., Myers, C. A. and Sharp, A. J. 1994. A thousand years of environmental change and human impact in the alpine zone at Mt. Kosciusko, New South Wales. Australian Geographer 25, 77-87.

Dodson, J.R. and Mooney, S.D. 2002. An assessment of historic human impact on south-eastern Australian environmental systems, using late Holocene rates of environmental change. Australian Journal of Botany 50, 455-464.

Hope, G.S. 1996. A report on the environment of Mt Scabby and palaeoecological analyses of swamp and stone arrangement sediments. Unpublished report to ACT Parks and Conservation Branch, ACT Government. 12pp

Hope, G.S.1997. Report on additional field investigations on Mt Scabby and Mt Bimberi in the Australian Capital Territory. Unpublished report to ACT Parks and Conservation Branch, ACT Government. 10pp.

Hope, G.S. 1998. Report on Little Creamy, Rock Flats and Lower Cotter Source Bogs in the Australian Capital Territory and Yaouk Swamp, New South Wales. Unpublished report to ACT Parks and Conservation Branch, ACT Government. 8pp

Hope, G.S. 2003. The mountain mires of southern New South Wales and the Australian Capital Territory: their history and future. Pp 67-79 in J. Mackay and Assoc. (eds.) Celebrating mountains. Proceedings of an International Year of the Mountains Conference. Jindabyne, Australian Alps Liason Committee.

Hope, G.S. and Southern, W. 1983. Organic deposits of the Southern Tablelands region, New South Wales, Unpub Report, Sydney, NSW National Parks and Wildlife Service.

Jackson, W. D. 1973. Vegetation of the Central Plateau. Pp. 61-86 in M. Banks (ed). The Lake Country of Tasmania. Roy. Soc. Tasmania, Hobart.

Kemp, J. 1993 The end of the Pleistocene in the southern tablelands, southeastern Australia. Unpubl. BA thesis, Dept Geography, ANU.

Kershaw, A. P. 1998. Estimates of regional climatic variation within southeastern mainland Australia since the last glacial maximum from pollen data. Palaeoclimates 3, 107-134.

Kershaw, A. P. and Strickland, K. M. 1989. The development of alpine vegetation on the Australian mainland, in R. Good (ed. ), The Scientific Significance of the Australian Alps, Canberra, Australian Alps Liaison Committee, 113-126.

Kershaw, A. P., Reid, M., Bulman, D. Aitken, D., Gell P., McKenzie, M. and Hibberd, J. 1993. Identification, classification and evaluation of peatlands in Victoria. Unpubl. Report to Aust. Heritage Comm.

Macphail, M. K. and Hope, G.S. 1985. Late Holocene mire development in montane southeastern Australia: a sensitive climatic indicator, Search 15, 344-349.

Martin, A. R. H. 1999. Pollen analysis of Digger's Creek Bog, Kosciuszko National Park: Vegetation history and tree-line change. Australian J. Botany 47, 725-744.

Mooney, S.D., Watson, J.R. and Dodson, J. R. 1997. Late Holocene environmental change in an upper montane area of the Snowy Mountains, NSW. Australian Geographer 28, 185-200.

Siegel, D. I. 1992. Groundwater hydrology. Pp 163-172 in H. E. Wright Jr., B. A. Coffin, N. E. Aaseng (eds.) The Patterned Peatlands of Minnesota. Univ Minnesota Press, Minneapolis.

Whinam, J. and Buxton, R. 1997. Sphagnum peatlands of Australasia: an assessment of harvesting sustainability. Biological Conservation 82, 21-29.

Whinam, J. and Chilcott, N. in press. Floristic description and environmental relationships of Sphagnum communities in NSW and the ACT and their conservation management. Cunninghamia.

Whinam, J., Eberhard, S. Kirkpatrick, J. and Moscal, T. 1989. Ecology and Conservation of Tasmanian Sphagnum peatlands. Tasmanian Conservation Trust, Hobart. pp107.

Wimbush, D. J. and Costin, A. B. 1979. Trends in vegetation at Kosciusko. Aust. J. Bot. 27, 741-871.

Whinam, J., Hope, G.S., Adam, P., Clarkson, B.R., Alspach, P.A. and Buxton, R.P. 2003. Sphagnum peatlands of Australasia: the resource, its utilisation and management. Wetlands Ecology and Management 11, 37-49.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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