How humans have changed natural environments
On The Science Show with Robyn Williams
Download How humans have changed natural environments (10.84 MB)
Wherever you look the effect of human influence is seen in the natural environment. David Mabberley describes the impact, such as the Australian Aborigines’ use of fire and the use of bison by native North Americans which is thought to have extended the prairies. In Africa, human pressure on the environment including poaching is seeing the decline of pachyderms such as elephants, rhinoceros, or hippopotamus, and other animals, and plants reliant on them for dispersal. In Britain, there is no original vegetation left other than the odd mountain top or sea cliff.
Painting by Numbers The life and art of Ferdinand Bauer
Author: David Mabberley
Published by NewSouth Books
Speaker
David Mabberley
Former Director Royal Botanic Garden Sydney
Presenter
Robyn Williams
Producer
David Fisher
Duration: 7min 53sec
Broadcast: Sat 5 Dec 2020, 12:01pm
Robyn Williams: We end with another book and another author in this year of Captain Cook. Remember him? Dr David Mabberley takes us back to those European beginnings in Australia.
David Mabberley: When Lieutenant James Cook came to Australia in 1770, he and his naturalist super-cargo, Joseph Banks, were surprised by the relative openness of the vegetation at Botany Bay, as was their natural history artist Sydney Parkinson who wrote, 'The trees, quite free from underwood, appeared like plantations in a gentleman's park.' Everywhere Cook and other European commentators wrote of smoke from fires set by Aboriginal people. These observations are but a small part of the huge corpus of literature and illustrations brought together by Bill Gammage to make the compelling case for the ancient very heavy fire management and therefore enormous botanical modification of eastern Australia by Aboriginal people, long before European settlement.
The first Australians had modified, largely by fire it would seem, the Australian landscape, such that they could coexist in an apparently sustainable way with the plants and animals here. In many parts of the country, the highly modified vegetation known as a fire climax, dominated by those of the original tree species adapted to fire regimes due to lightning, expanded symbiotically with the clever new bipeds, at the expense of less fire tolerant species.
With the opening up of the vegetation and their increasing prominence, grasses, adapted to tolerance of grazing marsupials palatable to humans, were therefore maintained in the landscape because their usual ecological successors, trees, would have been nibbled away as seedlings.
The human/fire/grass/grazing-animal system is not unique to Australia, but by the time of the first Dutch and British arrivals here, the first Australians had had tens of thousands of years to reach such a kind of mutualistic equilibrium. But it would be foolish to have some kind of rosy Rousseau-esque view of that first human infiltration of the continent. As it was to be with later European conquest, there is likely to have been a number of casualties in terms of animal and plant extinctions. It is still hotly debated as to how much of the original megafauna, for example, was helped on its way, but the story in other parts of the world suggest that the arrival of the first humans had, as usual, a devastating effect.
Humans are good at ecosystem modification, sometimes with disastrous consequences for them and the rest of the environment. In terms of the well-known collapse of civilisations like the Maya, but the speed with which this modification happened in the distant past is shown by the example of Europe. With the withdrawal of the ice sheets at the end of the last glaciation, the tundra vegetation was grazed by animals, including mammoths, and we know what happened to them! In an urbanising Africa and Asia today, we are now witnessing the similar end of the pachyderms, besides many, many other animals and associated plants reliant on them for disbursal.
In Europe, as it warmed, there came a forest maximum. But if you travelled to, say, Britain today, there is no original forest, in fact no original vegetation left at all, save perhaps on a few mountaintops and sea cliffs. The whole North European landscape is an artefact of just 10,000 years of human activity, and such landscapes were those over much of eastern and other coastal Australia in 1770. What is surprising in Europe is that the richest habitats today include grasslands with orchids and other small plants that must've been very rare in the forest maximum and are maintained by the incisors of introduced animals, particularly sheep. Take away the sheep, and a species-poor secondary scruffy woodland appears.
Similarly, native North Americans extended the prairies through their management of bison. The eastern United States was in fact less wooded than it is today, and firewood was a precious resource, so that the locals on seeing Europeans arrive by ship drew the reasonable conclusion that the settlers must've run out of firewood at home, the only good reason to move away.
Similarly, in the upper Blue Mountains where I live, the forest surrounded settlements, now called Blackheath and Mount Victoria, were visited by Governor Macquarie in 1815. He named them Hounslow Heath and One Tree Hill. You do not give such names to heavily forested places.
The botanical revelation that comprised the European recording of Australia's plants from 1606 until the arrival here of Charles Darwin in 1836 was the result of a combination of pursuits with different motives. The initial search for riches comparable with those in South America yielded little, Terra Australis turning out to be a largely arid continent with no crops suited to European agriculture, while the immense mineral wealth of Australia remained largely hidden.
Then came the concern about rival spheres of influence of European powers in the Pacific, especially Britain and France, the real reason for major expeditions being dispatched and land claimed. Incidental to establishing such presences was the collecting of natural productions, usually with a hope that these would be resources to allow colonies to survive without financial support from their European masters.
Charles Darwin visited Australia in 1836 and later in his monumental book, Variation of Animals and Plants under Domestication, effectively the evidence for much of his theory of natural selection in the hastily drawn up Origin of Species, he wrote of the potentially economic plants in Australia: 'It has often been remarked that we do not owe a single useful plant to Australia or the Cape of Good Hope or to New Zealand. Their plants have not been improved and consequently cannot compete with those which have been cultivated and improved during thousands of years in Europe.'
Similarly blinkered, shortly afterwards Thomas Livingstone Mitchell misinterpreted Aboriginal grain harvesting for hay making, when in fact there was what has now been posited as an Aboriginal grain belt right across the interior of the country, with grindstones argued to have been made up to 25,000 years ago.
It is true that internationally traded edible Australian commodities comprise products from species encountered by Europeans after Darwin's visit and that he was echoing opinions considered irrefutable. In fact, at first the most useful species commercially were the timbers, most of which were then still to be described scientifically. Such included red cedar, Toona ciliata, especially from the Hunter Valley, hoop pine, Araucaria cunninghamii, from the Brisbane area, and many eucalypts, Sydney blue gum, Eucalyptus saligna, being said to be the most generally useful of all the Australian woods.
Robyn Williams: Dr David Mabberley, former director of our oldest scientific institution, the Royal Botanic Garden, Sydney. His books are superb. The Florilegium is available any day now.
