https://www.abc.net.au/radionational/programs/scienceshow/australian-trees-growing-all-over-the-world/12974558
Robyn Williams: And so to the final in the series of talks we've had from botanist, Professor David Mabberley, formally from the University of Oxford and the Royal Botanic Garden Sydney. This time, how we have massacred the forests ever since Europeans turned up. And land clearing, as you know, has until now given us a get-out-of-jail card in climate accounting of emissions.
David Mabberley: The establishment of a British prison camp in Port Jackson in 1788, today's Sydney, as well-planned along European lines as it had been, was followed by a major problem for the fledgling white New South Wales, namely it imported more than it exported. For example, in 1811-12, merchandise imported from Calcutta was almost 20 times as valuable as exports to India. The search for goods for the Indian and Chinese markets led to coal being first sent to India in 1799, but timber helped too. Red cedar was sent as early as 1795, and oak, probably she-oak, by 1803.
The British Admiralty ordered that empty convict transports returning to England should carry cedar and other timbers. As early as 1795, there were government attempts to control cedar getting. The first organised fellings in the Hunter Valley where in 1801. The best cedar, resembling Honduras mahogany, was considered to be that from the Hunter. It was used for doors, window frames, furniture, coffins, for boat building and light vehicles and even for the panelling in Sydney's trams. Red cedar trees to 60 metres tall were formally plentiful on the alluvial flats of the larger rivers of New South Wales.
In 1829 a Scottish journalist Robert Mudie wrote prophetically of it as 'the most esteemed timber and would probably continue so until the forest be exhausted.' In fact it was almost entirely worked out, and today stands survive only in scattered remote localities in New South Wales and Queensland.
More pervasive in Australia are the eucalypts or gum trees, a term coined by Joseph Banks. According to government records, in 2013, eucalypts made up three-quarters of Australia's forests and woodlands, 92 million hectares. The first eucalypt to be grown out doors in Europe was a swamp mahogany, Eucalyptus robusta. It was planted north of Naples in Italy in 1792 and was being grown under glass in New York by 1811. In 1827 it was noted of Sydney blue gum, Eucalyptus saligna, that large quantities of it had been exported to England in the shape of plank, and that it was used locally in ship building, beams in houses, furniture and fence posts. By the 1860s, eucalypts were being used for paper production, for which their fibres are well suited.
Of the 800 or more eucalypt species in Australia, over 200 have been established in cultivation elsewhere. The tallest planted trees in the southern hemisphere are Sydney blue gums, planted in South Africa in 1906. They are also the tallest of all trees in all of Africa.
Blue gum, Eucalyptus globulus, a Tasmanian species extending to Victoria, has had the greatest global impact, reaching Africa in 1828 as nine seedlings via Mauritius. Blue gums are usually planted for paper pulp, and the timber is used in construction and charcoal making, but they have become invasive in many countries. They were introduced to California in the 1850s with the gold rush, and large-scale plantings began in the 1870s. In the 1860s, trees were established in Portugal and likely in Spain, even before that. The landscape of these countries, as also of much of North Africa, India, the eastern Mediterranean where they were planted to drain malarial swamps, Madagascar, Brazil, Colombia, Peru, Chile, and Ecuador has been transformed, though eucalypt plantings in Ecuador at least have removed pressure on native forests for firewood.
Blue gum is very successful in Africa at high elevations, as in Ethiopia, which had 250,000 hectares of it by 1993 contributing to Africa's total of 1,636,000 hectares, approaching double the area of natural stands in Australia. The very productive plantations used as a source of fuel enabled the first permanent capital, Addis Ababa, to be settled. In Australia, blue gum makes up 65% of all plantation hardwood, occupying perhaps 450,000 hectares. The total area of eucalypt plantations in Australia grew from almost nothing in 1998 to about a million hectares by 2008, spurred by a massive influx of finance, encouraged by the Managed Investments Act of 1998, which turned plantations into tax effective investments. But the global financial crisis of 2008 to 2009 saw off many of the companies involved.
With a bad reputation in many parts of the world because of invasiveness, eucalypts, some 14 species, have become naturalised in Europe, as have Australian species of hakea and 10 of acacia, wattles. Acacia, with about 1,053 species, is by far Australia's largest genus of plants. According to the government records, acacia forest is second only to eucalyptus forest, occupying in 2013 some 9.8 million hectares or 8% of the forest estate. The genus acacia occurs in all climatic regions of Australia and has a wide range of ecological tolerances. It has long been used as a food source and medicine, and for making tools and weapons. Golden wattle is in the national floral emblem, and the green and gold of acacias form the sporting colours for Australia.
Today, acacia species are perhaps used not so much in Australia for ornament as for soil rehabilitation because they fix nitrogen in their root nodules. Many species are grown in plantations in tropical and subtropical regions for industrial wood and for the bark, rich in tannin. They are increasingly important for fast-growing firewood and biomass. Australian blackwood, Acacia melanoxylon, is the best-known and most valuable temperate acacia timber species. It is commercially harvested in Tasmania, but most of the plantation timber on the world market is grown in South Africa, Chile and New Zealand. Black wattle bark from our Acacia mearnsii is a major source of commercial tannin used for leatherwork and adhesives, but Australia imports it from other countries.
In Australia itself, there were, even in the early 19th century, rising concerns about possible local extinctions of plants in the Sydney area. The scale of land clearing in many British territories, already with Europeanised agricultural systems, led the director of Kew Gardens in England to write: 'Many of the small local genera of Australia, New Zealand and South Africa will ultimately disappear, owing to the usurping tendencies of the emigrant plants of the northern hemisphere, energetically supported as they are by the artificial aids that the northern races of man afford them.'
By 1900, around 35% of New South Wales had been cleared or partly so, while 75% of the nation's rainforest had already gone. By the 1990s, some 300,000 tree ferns and grass trees were taken annually from the wild by the landscaping industry. Now over 1,000 Australian plant species are listed as vulnerable, and around 70 seed plant species are already extinct. However, contrary to the forebodings, the only planet genius to have been lost is Streblorrhiza, an attractive legume from Norfolk Island in the 19th century, and neither New Zealand nor South Africa has so far lost any.
Robyn Williams: Dr David Mabberley in the Blue Mountains. His book, Botanical Revelation: European Encounters with Australian Plants Before Darwin, will soon once more be in our shops. And yes, clearing land has just been removed as a dodge for our emissions accounting, our Kyoto subterfuge.
