Pine-Buloke Woodland is found on flat to slightly undulating landscapes on sandy-loam soils, over a calcareous substrate, in north-west Victoria. The altitude range is generally between 50 and 150 m above sea level and the rainfall varies from 250 to 450 mm a year. About 45% of the area once supporting Pine-Buloke in Victoria falls on public land while a little over 35% is represented in conservation parks and reserves. About 50% of all Pine-Buloke has been permanently cleared for agriculture or urban development. In most areas Pine-Buloke is bordered by the Red Gum, Mallee, Grassland or Black Box Woodland ecosystems.
Pine-Buloke is characterised by a generally sparse canopy of
Callitris gracilis (Slender Cypress-pine) or Allocasuarina
luehmannii (Buloke) or both, usually 10-20 m tall, over an often
dense understory of medium-sized to small shrubs and short-lived herbs
In some areas the main tree species may be replaced by or grow in
association with similar species such as Callitris glaucophylla
(White Cypress-pine) or Casuarina pauper (Belah).
Pine-Buloke is the only inland woodland or forest ecosystem which is not dominated by one or more species of Eucalyptus. The four principal tree species, from two plant groups, are all leafless, wind-pollinated and produce their seeds within small woody cones, yet the two groups are not related. The confusingly named cypress-pines are conifers and the only Victorian representatives of the Cupressaceae (so they are really cypresses rather than pines) while Buloke and Belah are primitive flowering plants in the Casuarinaceae. Early settlers in the dry country sought out the Pine-Buloke because it often meant more fertile country, with better forage for livestock, than much of the Mallee or Black Box and because the timber was useful. The Callitris timber is light and fairly soft but it is very durable and is resistant to termites, while the Buloke and Belah timber was considered to possess similar, although slightly inferior, qualities to European oaks (hence the general common name she-oak, a feminine and weaker form of oak). Buloke was particularly good for making bullock yokes which probably gave rise to its common name.
A serious problem that the settlers quickly found with grazing Pine-Buloke was that none of the tree species regenerated well when sheep and rabbits were in substantial numbers. The foliage of the young seedlings was both palatable and sought after by the grazing mammals. In addition the cypress-pines would often die, and fall over, if the population was thinned and individual trees were isolated. The loss of the cone-bearing trees also meant a drop in the numbers of cockatoos that feed on, and help disperse, their seeds
The understory structure and composition varies considerably across the Pine-Buloke range. The tallest component regularly includes a number of medium-sized shrub species indicative of semi-arid woodlands, such as Cattlebush (Alectryon oleifolius), Sugarwood (Myoporum platycarpum), Weeping Pittosporum (Pittosporum angustiflolium), Hop Bush (Dodonaea viscosa), Needlewood (Hakea tephrosperma) and emu-bushes (Eremophila), all of which are important browse plants for kangaroos and domestic stock. Several of the species produce an abundance of nectar-rich flowers and fleshy fruits which are significant for local bird and insect populations. In good years the largely nomadic nectivorous, frugivorous and insectivorous birds will often be present in large numbers.
The lower story of shrubs supports members of the Chenopodiaceae (Enchylaena, Einadia, Sclerolaena, Salsola, Atriplex, Maireana, Rhagodia), all of which are well adapted to the low and uncertain rainfall regime and have a variety of tolerance mechanisms to deal with it. Many have hairy or waxy surfaces to the leaves and stems, all have small, wind-pollinated flowers, some have spiny fruit, several are succulent and most grow slowly and store nutrients in their root systems. Some species (Enchylaena, Rhagodia, some Atriplex) have fleshy fruit over much of the year and so are an important source of food for birds and some lizards. Their numbers often increase in areas where the more palatable, but often short-lived, herbs and grasses of the ground layer have been grazed. When the native grasses and herbs are in large numbers, after spring or summer rains, ground-feeding birds, such as parrots, pigeons and cockatoos, become common. If these species are absent, due to heavy grazing pressure or drought, then the birds numbers will decrease.
Pine-Buloke is one of the most widespread but fragmented of the inland ecosystems. Even in the Murray-Sunset, Hattah-Kulkyne and Wyperfeld national parks the vegetation shows clear signs of disturbance with many of the mature trees represented only by stags (dead but still standing) or fallen logs and seedlings are only found in rabbit and kangaroo exclosures. The ground flora is often dominated by non-native species such as Red Brome, Mediteranean Turnip, Cat's-ear, Horehound and Sow Thistle, all of which have been introduced as contaminants when agriculturally desirable grasses and clovers were sown. Most of these sites were, of course, once used for agriculture and became part of the parks system in relatively recent times after much of the damage to the natural ecosystem had been done, damage that was well documented by the Victorian Forests Commission as early as the 1930s. Of particular concern to the Commission was the heavy clearing of cypress-pines, Buloke and Belar, which was seen as the loss of an opportunity to develop an important and sustainable dryland timber industry in favour of marginal and barely sustainable wheat and sheep farming.
The Commission's lament was well-targeted for today, despite being still relatively common over a geographic range that extends beyond the Pine-Buloke ecosystem to include almost 30% of Victoria, Buloke populations have been reduced to less than 5% of what they were at the time of European settlement. The majority of stands outside of parks are small, often less than a dozen mature trees, on roadside verges or paddocks, and there are very few signs of regenerating juveniles in most areas unless fenced exclosures have been established by land owners of government agencies.
© Paul Gullan, Viridans Biological Databases