These images show Wyperfeld National Park, Victoria, in southeast Australia. The park is native shrubland-- the Australian "bush"-- and appears in the Landsat images as dark red. Grazing land appears pink, and cropland is a green-yellow pattern. Fires occur in the park almost every year, leaving huge fire scars.

This area's dry climate lies between wet coastal forest and interior desert. Within these images, the Wimmera River flows from the wetter south to the drier north, where it dies in a chain of lakes. In these three Landsat images (1975, 1985, and 1999) the southernmost lake (Lake Hindmarsh) is always filled, the northernmost (Lake Agnes) is always dry, and the middle lake (Lake Albacutya) is wet in 1975 but dry thereafter, having last filled from 1974 to 1982.

Before European settlement this region was near-forest-- shrubs and small trees growing in varying density, with an understory of shrubs or grass. From the 1840s on, much of this bush was burned off to clear land for farming. Forested area (including shrubland) decreased in this region of Australia from an estimated 90% in 1869 to only 30-40% by 1987. Wheat yields in this region were high, so people tried farming even the areas with poorer or sandier soils. Crop failure in these sandy areas gave Wyperfeld the deceptive name "the Big Desert". These sandy areas can be seen in the Landsat images as sand ridges in the park, and as pink areas outside the parks, representing grazing land.¹

By the late 1800s, some Australians were trying to preserve natural lands, including the nationally symbolic "bush". The Forest Act of 1907 established forest reserves, some on abandoned homesteads, including part of Wyperfeld in 1909. After the Second World War the increasingly mobile and urban population desired more parks. In the 1960s the government proposed a partial development of the "Little Desert" (visible south of the "Big Desert"); in the backlash of public outcry the plan was canceled, the Little Desert National Park was greatly expanded, and a national conservation agency was created.²

Wyperfeld National Park is now 100,000 hectares, the largest in Victoria, with its western half an official wilderness. The park is habitat for black-faced mallee kangaroo, desert hopping mice, 50 species of lizards and snakes, and 250 species of birds including parrots and eagles. Mallee fowl, a rare mound-nesting species almost extinct by the 1950s, also live in Wyperfeld's vast shrubland.³

Much of the park's vegetation is mallee, a type of shrubland dominated by several sparse, tall varieties of eucalyptus. These eucalyptus have large underground tubers which sprout several stems after a fire, giving the mallee its distinctive look. The vegetation ranges in structure from short heath to tall, open woodlands. Areas along the river are dominated by river red gum trees, which grow in the wetter soil there, and by black box trees, which grow in the slightly drier soil. These trees act as a natural record of floods, since they germinate in wet soil. The park also has stone-forming fungi, whose rootlike feeding-threads cement the sandy soil particles into underground "stones" of up to 20 pounds. These stones incorporate black rings of ash, forming a natural archive of fires.⁴

Fires in the park, 1973-1999

Southeast Australia has a history of severe fire problems, with some historic deadly fires such as Ash Wednesday of 1983, and lesser fires almost every year. The state of Victoria averages about 19 large fires (over 1,000 hectares) per year. These fires are often fast like grassfire but more intense. The winter rains which benefit wheat farming also aid the buildup of plant matter, which becomes highly combustible during the dry summers. Perhaps 60% of the fires in Wyperfeld are started by lightning, with the rest from various human accidents and purposes, including fuel reduction. Since the 1950s, Australians have systematically set controlled fires to reduce the risk of dangerous fires later. Wyperfeld staff currently set fuel-reduction fires along the park's edges but fight all accidental fires, as required by law.⁵

These fires kill individuals, but communities of living things survive. Studies elsewhere in Victoria indicate that 2-4 years after a fire, the forest floor is again littered with small twigs and leaves, the habitat for many small animals. There are more plant species in the area than before the fire, though frequent burning certainly can kill out some species. Forest studies show that different post-fire stages favor different species; mice do well right after a fire, for example, but some birds do better in long-unburned or intermediate areas. Now that habitat is restricted to "islands" of parkland, there is danger of an entire park being burned out, with no adjacent communities to recolonize the burned areas.⁶

The Landsat images here show a stark change from unburned bush in 1975 to burn scars over 20 miles long in 1985 and 1999. The age of the scars can be estimated by their color; old scars are almost as darkly red as the bush, half-regrown scars are only pink, and the newest scars are very bright sand, or even black with ash.

But to accurately document the fires more data are needed. Landsat images are available for many dates, from various sources, but such a time series would be very expensive. Here as a substitute we use Landsat previews-- small, low-resolution Landsat samples from Internet catalogs. These are intended only to show cloud cover and major landmarks, but since these fire scars are major landmarks they appear clearly.

One preview is shown for each year, ideally from midyear, documenting the preceding fire season. Of the 27 fire seasons since the launch of Landsat 1, 22 seasons could be documented, and 14 of those 22 years showed new fire scars. The scars through 1998 were traced onto a single image, which was tallied into a chart. These data suggest that the large fires visible on these previews burn an average of 1-2% of the park per year, but the burning is heavily concentrated into a few seasons which burn far more than that, such as 1980-1981 and 1998-1999.

Footnotes

Thanks to the staff of Wyperfeld National Park for assistance with this article.

1. Australian Surveying and Land Information Group, Atlas of Australian Resources: Volume 6, Vegetation: Canberra, Commonwealth Government Printer, 1990. Peter Woodgate and Peter Black, Forest Cover Changes in Victoria, 1869-1987: East Melbourne, Dept. of Conservation, Forests and Lands, 1988, p. 3-5. Vincent Serventy, Australia's National Parks; Landforms, Plants, Animals Revealed through Nature Reserves: Sydney, Angus and Robertson, 1969, p. 113. Wild Australia; A Recreational Guide to All Our National Parks: Sydney, 1988, p. 234. Thomas McKnight, Australia's Corner of the World; a Geographical Summation, Englewood Cliffs, N.J., Prentice-Hall, 1970, p. 68.

2. Woodgate, p. 3-5. Stephen Pyne, Burning Bush; A Fire History of Australia: New York, Henry Holt, 1991, p. 365. Wild Australia, p. 199.

3. Serventy, p. 113. I.T. Loane and J.S. Gould, Aerial Suppression of Bushfires; Cost-Benefit Study for Victoria: Canberra, Project Aquarius, CSIRO Nat. Bushfire Research Unit, April 1986, p. 57. Victoria Parks, "Wyperfeld National Park": Internet factsheet found May 1998 at http://www.dce.vic.gov.au/parks/mallee/wyperfld.htm. Wild Australia, p. 38.

4. K.W. Robinson, Australia, New Zealand and the Southwest Pacific: London, University of London Press, 1960, p. 180. Wild Australia, p. 235. Serventy, p. 113. McKnight, p. 37-38.

5. Loane, p. 1, 40, 183. Personal communication with Wyperfeld staff. Nick Collett, "Effects of two spring fires on epigeal Coleoptera in dry sclerophyll eucalypt forest in Victoria, Australia": Forest Ecology and Management, 76, 1995, p. 69-85.

6. Collett, p. 74. Loane, p. 182. Serventy, p. 113.

Other references

Valerie H. Boughton, 1970, A survey of the literature concerning the effects of fire on the forests of Australia: Harvard Press, Pymble, New South Wales, 40 pages.

Commonwealth Scientific and Industrial Research Organization, The Australian Environment: London, Cambridge University Press, 1960.

Dean Graetz and others, 1992, Looking Back; the Changing Face of the Australian Continent, 1972-1992: Canberra, CSIRO, Division of Wildlife and Ecology, 1992.

Alexander Rule, Forests of Australia: Sydney, Angus and Robertson, 1967.

Satellite images

LM2101085007516590 (Landsat 2 MSS, 14 June 1975)

LM5095085008516290 (Landsat 5 MSS, 11 June 1985)

L71095085_08519990603 (Landsat 7 ETM+, 3 June 1999)

The 1973-1985 previews are from EarthExplorer and GloVis (for 1975 and 1985 the full-resolution scenes were resampled), the 1988 image was scanned from Woodgate, 1988, and the 1989-1998 images are from Imagenet. There were no available previews for 1974, 1977, 1978, 1986, and 1987.

Map

Defense Mapping Agency, 1986 (compiled March 1986 from source material dated 1952-1982), Operational Navigation Chart R-13: edition 5, scale 1:1,000,000.

National Parks Service, Department of Conservation and Natural Resources, 1996, Map Guide: Mallee: reprinted May 1997 by Parks Victoria, scale 1:~570,000.

Photographs

All ground photographs were taken by Robb Campbell and Larissa McKenna, 7-8 May 1999. Thanks to David Martin and the rest of the staff of Wyperfeld National Park for their assistance.