Burning Bush. Stephen J. Pyne
contrast, E. deglupta penetrated into New Britain, New Ireland, the Celebes, and the Philippines—the only eucalypt to cross the classic Wallace Line. In the process it shed most of its Australian traits and entered the rainforest, thronging gregariously onto wet, lowland sites. No longer did it seek out niches thrown up by disturbance or seasonal aridity; it chose another, alternative path. The farther it distanced itself from Australia, the further it sloughed off those attributes that accounted for the dominance of Eucalyptus within Australia. As a result, neither E. urophylla nor E. deglupta survived in Australia, and may, in fact, have emerged outside Australia altogether. E. deglupta, in particular, lost completely any affiliation for fire. Fire destroyed it.
Clearly the special status of Eucalyptus within Australia depended on its special circumstances—its isolation, its pattern of disturbance and aridity. Yet, paradoxically, this most indigenous of Australian flora has been successfully transplanted not only throughout ancient Gondwana but into Eurasia, Africa, and North and South America. In the early years the French more than the British actively promoted eucalypts (most often E. globulus, the blue gum). It was hoped that gums would become a valuable hardwood, provide fuelwood, assist agriculture by establishing windbreaks and shelterwoods, and decorate the countryside with attractive ornamentals. Eucalypt oil was promoted for medicinal and commercial purposes, as an antimalarial agent and as a chemical base for perfumes. French explorers to Australia returned to Paris with seeds, and from the Jardin des Plantes eucalypts were propagated throughout the Mediterranean littoral. Britain soon followed suit, moving Eucalyptus out of the category of an ornamental for estate aboriculture and extending it through Kew Gardens into its African and Asian colonies. Italy, in turn, became another center for export, largely into North Africa. The Trappist monks of the Tre Fontane monastery inaugurated perhaps the most celebrated experiment when, in 1868, they planted thousands of eucalypts in the Pontine Marshes in the pious hope that the mysterious, aromatic “gums” would purge the miasmic swamps of malaria. Only with the accession of the indefatigable Ferdinand von Müller to the status of colonial botanist in Victoria did Australia become an active distributor.
About twenty to thirty species define the emigrant eucalypts. Their chief liability is their intolerance to extreme cold—a reason why their range in central and alpine Australia is restricted, and another legacy of their Gondwanic heritage in a rainforest and of Australia’s migration toward the equator. But in Mediterranean climates, especially, Eucalyptus has proliferated. It thrives in Spain, Portugal, Italy, Turkey, Israel, and such islands as Corsica and Cyprus. It has been widely planted in Africa—the northern littoral of the Mediterranean, the southern and eastern veldt, the Ethiopian plateau, the Congo basin. Eucalypt plantations are extensive in Brazil, and they have reclaimed otherwise denuded plains in Chile, Ecuador, and Argentina. Gums are grown in China and India, where they are praised as fast-growing fuelwood and cursed as thirsty aliens. Eucalypts clothe patches of the Coast Ranges of California, where they were promoted by various interests (including the Southern Pacific Railroad), often as a surrogate for that enduring California passion, real-estate speculation. Eucalyptus has successfully transplanted to a panoply of islands from Madagascar to Mauritius, from Sri Lanka to the Seychelles, from Easter Island to Alcatraz. Eucalypts grace the royal palaces at Katmandu and Addis Ababa. Where Australian soldiers have fallen on foreign battlefields, local gravesites are framed with eucalypts. (Poignantly, they refuse to grow on the cold flanks of Gallipoli.)9
The reasons for the success of the emigrant eucalypts are several. They flourish in climates similar to those they knew in Australia. They were often unpalatable to local browsers (even goats). No less, there exists a strong fertility gradient between Australia and most other lands such that it is often easier to export indigenous plants from Australia than to import exotics into it. Only a special suite of organisms could thrive under Australian conditions, and then primarily if the native biotas were upset beyond their normal tolerances. But transplanting flora like eucalypts that had evolved in a nutrient-deprived and droughty environment into relatively rich, well-water sites was a formula for successful colonization. The outcome could be extraordinary. Between 1950 and 1974, for example, eucalypt plantations increased worldwide (including China) from 0.7 million to 3.7 million hectares—and continue to rise.
It is probable, too, that its alliance with humans explains the ubiquity of eucalypts in Australia. They moved overseas because humans took them into compatible environments. They did not have to transcend endless oceans or navigate through rainforest, a biota they had abandoned during their evolutionary history: they could appear directly on suitable sites. In most cases, those sites could not offer worse conditions of soil and aridity than they had known in Australia. Native organisms were kept off balance, the site chronically manipulated, by human intervention. With a few exceptions, free-burning fires were less pervasive, and when they came, they inflicted less damage than on native trees.
Its enlarged dominion has had a cost, however. The eucalypts’ interdependence with humans could not eliminate their more ancient interdependence with fire. They continued to behave as though fire were still a principal ally, persisted in littering fuels as though surface fires routinely passed over them, acted as though fire would remain instrumental in purging the biota of competitors, in restoring conditions for regeneration, in recycling scarce nutrients. Those environmental conditions that allowed emigrant eucalypts to prosper so gloriously also encouraged an excess of unchecked fuels. Interestingly, other fire-hardened scleromorphs from Australia like Casuarina and Melaleuca have also become major fireweeds in such exotic landscapes as south Florida. But these were weeds, unwanted escapees, not assisted emigrants.10
The environments that encourage eucalypt plantations also encourage eucalypt-dominated fire regimes. Not only commercial plantations, but other environments receptive to eucalypts have witnessed a rise in fire hazard. The transported eucalypts shed fuel as though they expected to burn. The Berkeley fire of 1923, which consumed about a fourth of the city and entered the University of California campus, was propelled in part by windfall and litter from extensive eucalypt plantings. The scene had little improved when an Australian fire specialist visited the Bay Area in the 1960s. Familiar with the intensity of eucalypt fires in their native setting, he gasped at the specter that greeted him—the intermixture of houses and giant eucalypts, branches and bark piled deep, a surreal scleroforest composed equally of Eucalyptus and houses. Shaken, he abandoned the conference tour and retired to his motel room, his head spinning with visions of holocaust.11
THE EUCALYPT AS AUSTRALIAN
The Australian bush owes its peculiarity, more than anything else, to Eucalyptus. No other continental forest or woodland is so dominated by a single genus. Other biomes on Earth have scleromorphs, most have grasses, and few are spared wholly from fire, but none has the combination that exists in Australia and has given the bush its indelible character. Eucalyptus is not only the Universal Australian, it is the ideal Australian—versatile, tough, sardonic, contrary, self-mocking, with a deceptive complexity amid the appearance of massive homogeneity; an occupier of disturbed environments; a fire creature.
But the ideal Australian is also the typical Australian. Its peculiar strengths delineate as well its weaknesses. The hostile environmental conditions that pushed the biota toward sclerophylly, the chronic disturbances that at once simplified and complicated the biotic ensemble, the alliance with fire that allowed a single genus to overrun a continent—all these were enormous strengths so long as those informing circumstances remained more or less in force. While the domain of fire in Australia had expanded, it ruled within an evolved order. If, however, those pressures were removed, if new biotic elements were introduced or significant portions extirpated, if the fire regime were reconstituted by new fuels or new sources of ignition, then those special traits could become liabilities.12
The bush was perhaps too dominated by Eucalyptus, and Eucalyptus perhaps too closely reliant on fire and, through fire, on Homo. The eucalypt was less a pyrophyte than a pyrophiliac: fire became a near addiction with its own peculiar perils. The tendency was to create more fire, as though the biotas linked by eucalypt and fire were a kind of chain letter, a leveraged biotic buyout sustained by ever-increasing infusions of fire. Any reform in the fire regime would upset not only