Thursday, November 12, 2009

Our Escarpment’s Vegetation

Before white settlement, the vegetation along the escarpment of the Great Dividing Range in the Toowoomba area would have looked very different.
It would have consisted largely of dry rainforest, with pockets and lines of dense moist rainforest in the gullies and stream beds. Both kinds of rainforest were described by the settlers as “scrub”, a term still often used for the drier types of rainforest vegetation.
There were plenty of permanent waterholes, such as the large one, still being marked on late 19th century maps, below Prince Henry Drive. There are still people who can remember swimming, on hot summers’ days, in the pool at the base of Highfields Falls.
Eucalypt grassland would have been restricted to ridgetops, probably existing in a more or less pure form only on those ridges which were traditional aboriginal travelling routes. Aborigines all over Australia regularly “cleaned up” such routes, by burning. White explorers followed them, because the going was easier, and these ancient travelways have since become our modern roads and highways.
It is worth noting that aboriginal use of fire normally resulted in only small areas being burned at a time. Most of it was done to improve the food-producing ability of the land, where the aim was to create a mosaic pattern of fire recovery areas of different ages. This gave them the maximum variety of foods.
One result was what they called a “clean” landscape, which wouldn’t carry a fire for long distances. Another was that areas of fire-sensitive plants such as rainforest and scrub species were not swept away, as they are nowadays by the runaway bushfires which are the result of post-European fire management - or the lack of it.
The process of wholesale clearing the escarpment’s rainforests and scrubs began in the earliest days of white settlement, when aborigines set extensive fires in attempts to get rid of the first invaders.
Timbergetters arrived with the squatters, felling rainforest trees at first, then turning to the eucalypts. Toowoomba’s early industries - a boiling-down works which produced tallow, and a fellmongery, as well as the steam sawmills which were soon introduced - used much of the “scrap” timber for fuel.
Settlers cleared as much of the “scrub” as they could, because they feared the aborigines who hid in it. They paid particular attention to exterminating small bunya trees, as bunyas were known to “attract” aborigines.
In the late nineteenth century the escarpment near Toowoomba was subdivided into tiny farms, mostly taken up by Irish settlers, who were energetic about clearing the land and keeping it clear, both manually and with fire. The result was the development of the current fire ecology, dominated by eucalypts and wattles, which invaded former rainforest territory. These fast-growing trees created the modern impression that our current fire-prone escarpment vegetation is the natural environment there.
The ease with which privet grows, wherever fire fails to keep the ground clear, tells another story.
Meanwhile the original waterholes and streams have largely dried up. Some of this has been from silting, as clearing exposed the soil. Some resulted from the change in groundwater levels which always results from the clearing of hilltop trees. Drought has an effect, of course, but it has been exacerbated by pumping from bores. Originally the greatest effect came from those used for market gardens, but recently the enormous increase in domestic bores in our suburbs, used largely for watering gardens, has had an effect, with the escarpment streams drying up or being reduced to trickles. This is most easily seen in the huge change to Highfields Falls in recent years. Only 15 years ago I saw a large eel in the pool where now there is only a circle of dry kikuyu grass.
That praiseworthy group, the Friends of the Escarpment Parks, has worked very hard to restore some of our original environment. In this they were supported and aided by the Toowoomba City Council, and perhaps the new council is being as helpful.... There are also private landholders doing wonderful work of a similar kind.
It’s hard to say, though, which is having most effect - the brave efforts at restoration, or the continuing destruction of our original landscape.

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