Australasian Plant Conservation
Originally published in Australasian Plant Conservation 19(2) September - November 2010, p 16-17
Havens and oases—the conservation value of stock routes in Queensland
Queensland Herbarium, Brisbane. Email: firstname.lastname@example.org
Figure 1. Aerial photo showing stock routes of Brigalow forest (dark stripes along roads) in the heavily fragmented landscapes of southern Queensland.
Figure 2. The rare daisy Cymbonotus maidenii growing between a roadside and cultivated paddock in the Darling Downs. Photo: Queensland Herbarium.
Figure 3. Mound spring in a stock route near Eulo.
Photo: Rod Fensham.
The land surveys that carve up the Australian landscape into blocks of tenure provide a continuous network of corridors originally intended for transporting stock from paddock to market. Some of these ‘stock routes’ followed the most expedient tracks across the landscape that had already been established by Aboriginal people. Many have been converted to roads, and are now also utilised as corridors for the underground transport of electricity, gas, water and the ever-expanding broad-band network. Amidst this network of utilities, their original purpose for moving animals on foot has been almost forgotten. They are still used by the pastoral industry but more as ‘long-paddocks’ called upon during droughts to yield the last vestiges of pasture.
Across Australia, stock-routes are well known as important havens for nature conservation, and this is no less the case in Queensland. In heavily fragmented landscapes the stock routes preserve some of the only natural remnants of the original vegetation. On the Darling Downs in southern Queensland, natural grasslands on rich alluvial soils have been converted to highly productive fields of cotton and sorghum. The remaining 1% of the grasslands are mostly along the stock routes lining the main highways through the district.
By their very nature, stock routes have a long history of grazing, but it is a very different style of grazing from that which occurs in the adjacent paddocks. During the first century of pastoralism, the stock routes would have been occasionally trampled to dust by large mobs of travelling stock. It is this heavy but sporadic grazing that is the hallmark of their management history. This allows the vegetation to recover and set seed, unlike in the continuously grazed paddocks. Stock routes in some areas also tend to have a history of regular burning.
Threatened ecological communities
A drive along stock routes preserving precious fragments of Brigalow forest (Figure 1), a curious scrubby vegetation type dominated by the silvery-leaved Acacia harpophylla, can give a false impression of the overall landscape. In the space of 50 years the Brigalow has been decimated, and the narrow stands of Brigalow provide a silver and green veil hiding cleared paddocks. The stock routes represent some of the last stands, particularly in the higher rainfall districts with the most arable soils. Unfortunately these last standing corridors have been invaded by exotic grasses making them vulnerable to fire that begins a vicious cycle driven by damaged canopies that allow for the growth of more grass and then ever-more fire.
Sometimes the stock routes border town commons, set aside as public land for various uses. Although often heavily grazed, these reserves are usually uncleared and so preserve important remnants of vegetation types that occupy more fertile land types, and have been largely obliterated in the district, such as Brigalow forest and Coolibah (Eucalyptus coolibah) woodland. The town commons at Yelarbon and Taroom are fine examples.
There are many rare plants that are largely restricted to fenced stock routes, including a suite of daisies that poke their large heads above the grass. Australia’s only native thistle (Stemmacantha australis), the Belyando cobbler’s peg (Trioncinia retroflexa) and others too rare to have common names (Cymbonotus maidenii (Figure 2), Rutidosis lanata and Senecio daltonii) are examples. Presumably such prominent and attractive plants are irresistible for cows and sheep and in the paddocks they are chewed to extinction. These plants seem to thrive on the disturbance of occasional grazing, and proliferate with fire.
An undescribed solanum (Solanum sp.) is one of Australia’s rarest plants, and is known from a single small population on a stock route near the town of Clermont. We have no record of its flowers or fruits, but its leaves are the size of dinner plates and unlike any other species. The herbarium labels on the historical collections suggest this plant can behave like a weed immediately after ploughing but cannot persist amidst crops and repeated cultivation. The plant does not seem to cope well without some form of disturbance, and has not been seen amongst the native grasses at the site for several years. It has underground stems and is expected to bounce back following the next fire.
Across the great expanses of western Queensland, the stock routes criss-cross intact landscapes. They are not fenced and you need a map to know where they are. However, the surveyors were instructed to position their course to provide links between reliable water so that stock could get a regular drink. Often they follow streams and pass beautiful Coolibah-lined waterholes.
Stock routes and watering reserves contain some of the most significant natural springs in Queensland. These tiny island oases (Figure 3) in an otherwise parched landscape are fed by the Great Artesian Basin. The community of native species dependent on the natural discharge of groundwater from the Great Artesian Basin is also a threatened ecological community. Biologists are still coming to understand the unique animals and plants living within these permanent wetlands. The major threat to the springs is the hundreds of bores that gush groundwater down open streams and rob the springs of their flows. A bore capping scheme is underway to alleviate this profligate waste, and the presence of the springs on public land should allow them to be better recognised and valued.
Now that trucking has become the normal mode of transport, stock routes are no longer as vital to the grazing industry, and the imperative to manage them as a public resource has diminished. These vast areas of land do require maintenance, including fencing and fire management, and government bodies seem keen to pass on the responsibility.
Surveys of the biological values and condition of stock routes for nature conservation have been conducted but must be completed before rational decisions about their future can be made. Perhaps they should be given a new status as conservation reserves, with management prescription that should include occasional grazing and regular burning as has happened in the past. Some, such as the strips of Brigalow, have high conservation values, but will need active management if they are to survive.