Tree ripping chain
This piece of anchor chain is part of a much longer chain which was pulled between two bulldozers to flatten trees and vegetation for land clearing in Queensland during the twentieth century.
In 1788, before the large-scale exploitation of the natural landscape, Australia had an extensive spread of vegetation, from dense rainforests to dwarf scrub and native grasses. A combination of economic pressures, greed and ignorance saw the dream of rural prosperity wither as the land proved it could not be mistreated forever. A combination of overclearing, over-grazing, introduced pests and drought has produced major land degradation. Today land clearing is seen as the biggest environmental threat facing Australia. Chief among those effects is salinisation, which occurs when the removal of trees causes water tables to rise, bringing salt stored in the soil toward the surface.
Almost as soon as colonists arrived land clearing began quickly and the resulting soil erosion could be seen even in the early years of settlement. In 1803, only 15 years after the foundation of the colony, Governor King issued a proclamation against felling trees along the banks of rivers and watercourses to stem the degradation. Once the demands for agriculture accelerated in the north, south and west, and King left the colony the proclamation was forgotten.
Land clearing was, and some in states still is, sanctioned by the Government. In many cases land clearing, referred to as improvements, were part of the terms of grants, leases and conditional purchases. As late as 1929 the NSW Department of Agriculture's "The Farmer's Handbook" devoted 30 pages to land clearing techniques and one small paragraph advising of tree planting to prevent soil erosion. Methods included felling by the axe and hand or mechanical grubbing out the stumps; burning, followed by the use of explosives including dynamite and gelignite to blow up large trees; ringbarking; and poisoning of trees with arsenite of soda.
Other methods of land clearing included the mallee roller, ball and chain, and anchor chain. The mallee roller evolved in the 1860s by wheat farmers in South Australia to clear mallee country by rolling with a tree trunk or old boiler then burning it. In Queensland both the ball and chain hauled by a bulldozer and an anchor chain hauled between two bulldozers were used to effectively smash down woodlands. The latter method continues to this day.
Overclearing and intensive use of land has led to salt creep, destruction of soil structure, soil erosion and lowering of soil fertility. Land clearing in Western Australia was linked to salinity of rivers as early as the 1920s. Community concern about land degradation developed in the 1930s and 1940s, leading the government to establish the first Soil Conservation Agency (NSW) in 1938.
Despite this, today Australia continues to clear more woodlands and forest than any other developed nation in the world and is the sixth greatest clearer behind, Brazil, Indonesia, the Sudan, Zambia and Mexico. Queensland is responsible for almost 80 percent of the clearing occurring in Australia which contributes to 13 percent of Australia's Greenhouse gas emissions.
Queensland has 1035 regional ecosystems, one third of these are endangered, of concern or threatened. Thirty percent of mammals and 10 percent of birds are presumed extinct, endangered, vulnerable or rare. Eighty-five percent of land clearing is to provide pasture for beef and sheep while the top ten companies own at least 3,000,000 square km of land. Between 1997 and 1999, 425,000 ha of land was cleared. This is over 1,150 ha per day or close to ten average suburban blocks every minute. Given this rate of clearing it is estimated that between 4.25 and 8.5 million birds are killed annually.
The Brigalow belt of acacia ecosystems in Central Queensland today has the largest rate of clearing in the state and the piece of anchor chain was retrieved from this area. Clearing of these woodlands creates a "woody weed" problem as it grows back as a thick woody regrowth. Native grass growth is suppressed in competition for water, light and nutrients, leaving the soil exposed and the country highly vulnerable to major soil erosion from wind and rain. The advantage of native vegetation is that it provides a natural filter to keep lakes and streams healthy and productive and reduces salinity in our waterways.
Legislation proclaimed in September 2000 in Queensland has done little to slow the rate of land clearing. The environmental cost will be increased salinity in Queensland as well as the southern states downstream in the Murray-Darling river system, South Australia, Victoria and New South Wales. Several states have sound native vegetation planning systems already in place, particularly South Australia, Victoria during the 1980s and the Australian Capital Territory and Western Australian has recently strengthened its land clearing controls. Conserving native bush is a far better and cheaper way of conserving biodiversity than tree planting and revegetation projects. Healthy, complex native bush communities are difficult, if not impossible to reconstruct once destroyed.