When botanists Joseph Banks and Daniel Solander set foot on the east coast of Australia in April 1770, they entered a botanical paradise. By chance, the landfall of Captain James Cook's "Endeavour" coincided with one of the most botanically rich areas of Australia and Banks and Solander spent countless hours collecting and drawing the numerous new plant species that confronted them. Earlier collections had been made by Dutch explorers on the west coast but the collections made during the voyage of the "Endeavour" were far more comprehensive and extensive.
In the 200+ years following European settlement, the Australian flora has suffered greatly in the name of progress. Surprisingly, the flora around the original settlement at Port Jackson has suffered somewhat less that is the case in many other parts of the country. This can be attributed to the fact that the rugged sandstone topography has made large-scale development an expensive proposition. Overall, however, it is believed that around 76 plant species have become extinct during the two centuries since European settlement with approximately another 301 species being at serious risk in the short term. Of course, no one knows how many species may have been lost before they were botanically described.
|Top: Acacia pubescens - at risk through too frequent fires. Bottom: Hakea bakeriana - at risk through lack of fire. Photos: Brian Walters|
Plant loss occurs through a variety of mechanisms not always due to human intervention. Natural processes may result in climatic changes which can lead to extinction or gradual evolution of species as they cope with the changed conditions. These are long term effects which may take place over millions of years. In contrast, plant loss due to human activities are far more dramatic and can produce irreversible effects in a few decades.
In 1984, Leigh, Boden and Briggs (see Further Information) described the main recognised threats to Australian plants and the number of species effected by each threat. These are:
In addition to these, a range of other threats include recreation, rubbish dumping, railway maintenance, water storage, insect attack, erosion. A number of species are effected by more than one threat.
Most of the impacts of human activities are obvious. It's not difficult to imagine the effect that urban development, quarrying, roadworks and agriculture might have on a rare plant in the area being developed. Other threats are more subtle in their impacts. For example:
|Phaius tancarvilliae - at risk through horticultural collecting.
Photo: Keith Townsend
|Grevillea batrachioides - at risk through low numbers existing in the wild. Photo: Brian Walters|
Further information on the key threatening processes affecting the Australian flora can be found on the website of the Department of the Environment, Water, Heritage and the Arts (see Further Information.)
Thanks to John Wrigley, Cas Liber, John Atkinson and Angus McLeod for providing comments and suggestions.