Box-Ironbark Forest

Box-Ironbark Forest (BiFor) is found on flat to undulating landscapes on rocky, auriferous soils, mainly in central Victoria.  The altitude range is generally between 150 and 600 m above sea level and the rainfall varies from 500 to 800 mm a year.  About 40% of the area once supporting BiFor in Victoria falls on public land while a little under one fifth is represented in conservation parks and reserves (most of which have been created in the past few years).  About 55% of all BiFor has been permanently cleared for agriculture, urban development or mining.  In most areas BiFor is bordered by Dry Sclerophyll Forest (DrySF), Red Gum or Grassland ecosystems.

BiFor is characterised by a dense to sparse canopy of box, ironbark and gum-barked eucalypts to 25 m tall, over a sparse understory of wattles and small-leafed shrubs, small and prostrate shrubs, annual and perennial herbs, and annual and perennial grasses. The principal trees are Eucalyptus microcarpa (White Box), Eucalyptus polyanthemos (Red Box), Eucalyptus tricarpa (Red Ironbark - in the west and south) or Eucalyptus sideroxylon (Mugga Ironbark - in the north-east), Eucalyptus leucoxylon (Yellow Gum) and Eucalyptus macrorhyncha (Red Stringybark).  In some areas these are replaced by or grow in association with Eucalyptus melliodora (Yellow Box), Eucalyptus goniocalyx (Long-leaf Box) or Eucalyptus nortonii (Silver Bundy).

Box-Ironbark Forest
Box-Ironbark Forest

The mammalian fauna consists of large grazers (kangaroos), medium-sized browsers (wallaby and occasional wombats), small ground insectivores  (antechinus), arboreal species, (koala, possums, gliders, phascogales), and bats.  Most of the birds are common woodland species of northern and western Victoria (fantails, thornbills, treecreepers, whistlers, rosellas, currawongs, robins, pardalotes, cuckoos, Kookaburra, owls, parrots, wrens) although some groups are in greater abundance than other ecosystems (honeyeaters, lorikeets, babblers).  The reptiles are mostly small arboreal and ground-dwelling skinks, blue-tongue lizards, dragons, goannas and snakes.  Frogs are uncommon and occur mostly in small dams and creeks.

BiFor is situated almost entirely within the Victorian goldfields.  Which means that during the gold rush years, 1851 to around 1870, it was subjected to intensive digging and clearing in the goldfields themselves, which was accompanied by extensive timber cutting for buildings, bridges, mine shafts and firewood in areas further afield.  The ironbarks and some of the boxes have very hard wood and were favoured for structural timber and firewood.  After the gold rush subsided the forests were still heavily cut for firewood to heat the houses and run the industry of the now substantial Victorian population.  In addition, huge areas of forest were cleared for pasture, although converted BiFor proved to be marginal for grazing purposes compared to the Grasslands and Dry Sclerophyll Forests of the surrounding country.

The trees of the BiFor are amongst the most prolific flowering eucalypts.  The spring-flowering Yellow Box has long been recognised as the best nectar producer in the state and has been a protected species and mainstay of the honey industry for nearly a century.  It is also a major source of nectar and pollen for lorikeets, honeyeaters and a wide range of invertebrates.  The winter-flowering Ironbark and Yellow Gum have the largest flowers of all forest eucalypts, and the autumn-flowering Grey Box and Red Stringybark provide food for the migratory Swift Parrot which over-winters in Victoria before returning to its breeding grounds in Tasmania.  The other eucalypts in BiFor stagger their flowering throughout the year so that there is always a pollen and nectar source for nomadic, migratory and resident birds.  As a consequence there are more species, and greater numbers, of honeyeaters and lorikeets in BiFor than any other ecosystem.  Nectar and pollen feeding birds such as the rare Black-chinned Honeyeater, the endangered Regent Honeyeater and Swift Parrot, the common Fuscous Honeyeater, Brown-headed Honeyeater and Musk Lorikeet, are all substantially more abundant in BiFor than elsewhere.

BiFor supports the largest numbers of Eastern Grey Kangaroos in the state, the long-term future in Victoria of the small arboreal carnivore, Brush-tailed Phascogale, is now heavily dependant upon its success in this ecosystem, and over a quarter of the Yellow-footed Antechinus and Squirrel Glider records are from BiFor. 

The future of BiFor will rely upon the integrity of its flora and there are significant problems with its maintenance.  The vegetation has been fragmented into various sized areas, some very small, each of which is surrounded by pasture and sometimes urban development, with the consequence of weed invasion and loss, or reduction in numbers, of local species.  The ironbarks have been the hardest hit from the intensive firewood harvesting in the 1900s, because of their superior burning properties, so their numbers are much lower and the trees much smaller than they would have been 100 years ago, a situation that is hampered by their naturally slow growth rate.  The groundcover contains an odd mixture of plants which includes some of the largest concentrations of orchids of any Victorian ecosystem (especially wax-lips, sun-orchids, beard-orchids, onion-orchids, leopard-orchids), a number of small herbs and shrubs which are most abundant in, or more-or-less restricted to BiFor (Cheiranthera cyanaea, Philotheca verrucosa, Xerochrysum viscosum, Pultenaea largiflorens, Acacia williamsonii, Stuartina muelleri), and a high proportion of relatively small annual and perennial weeds (fescues, quaking-grasses, hair-grasses, flat-weeds, onion-grasses, cape-weeds, clovers, chickweeds). 

Botanical management of the BiFor shrub and ground-layers is difficult because there is a need for significant manual labour in weeding and replanting programs.  The biggest problem with the weeds is that they are widespread and many of them are annuals, so removing an adult plant after it has set seed will have no real effect.  In addition to this it is often difficult for the unskilled worker to determine which species are weeds and which are native.  The almost ubiquitous, non-native flatweeds (Hypochoeris) have dandelion-like flowers that are very similar to those of the native Yam-daisy (Microseris), the native button-flowered herb, Cotula australis, can easily be confused with the introduced Cotula bipinnata, the non-native fescues (Vulpia) have similarities to some of the smaller wallaby-grasses (Austrodanthonia), native blown-grasses (Lachnagrostis) look every bit as weedy as the genuinely introduced hair-grasses (Aira), and the native shrubs, Cassinia arcuata and Acacia paradoxa, have long been considered as weeds of pasture country so their rightful positions as natives in BiFor is difficult to reconcile for some. 

One of the biggest challenges for BiFor is the expansion of the rural City of Bendigo which is unique in Victoria in being almost completely surrounded by conservation parks and reserves, many of which penetrate well into the inner suburbs.  While the close proximity of urban development and native (and near-native) vegetation is not new to Bendigo, the status of the bushland as national or regional park is.  The most recent conservation upgrade in 2002 has resulted in the creation of the Greater Bendigo National Park and the Bendigo Regional Park, from smaller parks, reserves and unclassified public land.  While this has generated a much wider range of building and development regulations in place for Bendigo, which will inevitably generate controversy and debate, many of the locals regard the new status of the surrounding vegetation as a tourist opportunity.  There are already catchphrases boasting to would-be visitors that Bendigo has the dual advantages of being close to wildlife within a conservation park but with the comfort of city living.  It may well be that money generated from the eco-tourism industry will help fund the management and rehabilitation of the local forest ecosystems, and that Bendigo can act as a model for other developing regional towns which are close to bushland..     

© Paul Gullan, Viridans Biological Databases