Visiting Fellow, Australian National University. Canberra. Act
The studies by Noel Beadle in the western Riverina and by Ted Moore in the east provide a detailed historical account of the vegetation of the region. They prepared maps of the probable state of the vegetation before European settlement began, and in their reports they described that vegetation and also discussed what had happened to it under grazing.
That work was done many years ago. Today any attempt at reconstructing pre-settlement vegetation attracts questions about the effects of Aboriginal fires. There is considerable debate on this subject. However, for the purposes of this talk I shall take the work of Beadle and Moore at its face value. I certainly get the impression from Bill Gammage's classical study of the history of Narrandera Shire that in this area the use of fire by the Aborigines was planned, controlled and localised.
There is a more recent picture of the changes that have occurred under European settlement in the 'Vegetation' volume of the Third Series of the Atlas of Australian Resources, with its two associated maps of the present vegetation of Australia and of the probable pre-settlement vegetation. This is the result of a national vegetation mapping project in which I was involved. Since it covers the whole of the country, the treatment of any particular region is, of course, at a relatively small scale.
I shall be discussing what has happened to each major vegetation type in the Riverina under settlement. I qualify that by adding that I shall be restricting myself to vegetation types dominated by trees. These are defined as forests if the trees provide projective foliage cover greater than 30%, and as woodlands if the cover is between 10% and 30%.
Red ironbark - tumbledown gum forest
The native vegetation of the poorer soils of the hilly country was a forest or woodland dominated largely by red ironbark, alias mugga ironbark (Eucalyptus sideroxylon), and tumbledown red gum (E. dealbata), often with cypress pines (Callitris species). This vegetation type persists on the rougher hills and in reserves, but in other places it has been thinned out considerably for grazing.
White box woodland
Large areas of massive earths and other soils in the eastern Riverina were formerly occupied by a grassy woodland dominated by white box (Eucalyptus albens), with yellow box (E. melliodora) and Blakely's red gum (E. blakelyi) locally dominant in moister areas. Today this vegetation type is almost entirely replaced by seasonal exotic pastures and seasonal crops, but occasional paddock trees show where it used to be.
Grey box - cypress pine woodland
The most widespread native vegetation type was a woodland dominated by grey box (Eucalyptus microcarpa) and white cypress pine (Callitris glaucophylla). It occurred in particular on duplex soils. Over most of its former area this vegetation type has been replaced by exotic pastures and seasonal crops, with occasional paddock trees to show where it used to be. However, there are some relic stands, and in some places the regeneration of the cypress pine has been encouraged.
To the northwest, the grey box gave way to poplar box, alias bimble box (Eucalyptus populnea), with an admixture of other vegetation types, dominated by mallee species of Eucalyptus or by belah (Casuarina cristata). The better-watered parts of this country have also largely been cleared for seasonal cropping in association with grazing.
Boree low woodland
To the west, and on heavy soils, the grey box woodland gave way to a low woodland dominated by boree (Acacia pendula) with an understorey of old man saltbush (Atriplex nummularia). Most of this low woodland has been greatly thinned out, and today the area is occupied largely by native grassland with scattered relic trees.
Black box low woodland
Especially in the west, low-lying areas subject to flooding were occupied by a low woodland dominated by black box (Eucalyptus largiflorens), with taller river red gum (E. camaldulensis) along the watercourses. Some relics of black box woodland remain, usually modified by grazing, but much of it has been replaced by exotic pastures and seasonal crops, especially in the irrigation area.
The current situation
The overall picture in the Riverina is one of the tree vegetation having been cleared or thinned. This is not the complete picture, of course. Some stands of trees do remain. Considerable numbers of trees have been left in some paddocks. There have been fenceline plantings and homestead plantings. Some kurrajongs (Brachychiton populneus) in paddocks have probably been planted. In some places the regeneration of cypress pine has been encouraged. But a general overview suggests that while trees are still a feature of the Riverina landscape, they occur typically as scattered old paddock trees in cleared land.
But how long will those trees remain a feature of the landscape? Old paddock trees must eventually die, and probably sooner rather than later, to judge from the evidence that isolated paddock trees are particularly susceptible to dieback. Bill Gammage has pointed out that many landholders are already re-planting trees, because they are well aware that trees shield stock and help to avert erosion and salinity. That is, they recognise that trees are indeed an 'essential farm ingredient'.
References and further reading
1. Australian Surveying and Land Information Group (1990). Vegetation. Volume 6, Atlas of Australian Resources, Third Series. AGPS, Canberra.
2. Beadle, N.C.W. (1948). The Vegetation and Pastures of Western New South Wales with Special Reference to Soil Erosion. Department of Conservation of NSW, Sydney.
3. Gammage, Bill (1986). Narrandera Shire. Narrandera Shire Council, Narrandera.
4. Moore, C.W.E. (1953). The Vegetation of the South-eastern Riverina, New South Wales. I. The Climax Communities. II. The Disclimax Communities. Australian Journal of Botany 1:485-567.
5. Soil Conservation Service of New South Wales (1982). Young District Technical Manual.*
*Coverage of vegetation and land use extends beyond the northern margin of Moore's study area.