by Bill Gammage
How many species there are will never be fixed since some cross-pollinate,69 but let’s say 700, five not native to Australia. They range from low shrubs and stumpy trees to Mountain Ash, the world’s tallest flowering plant. The tallest Mountain Ash known is 101 m, in southern Tasmania, yet in the Snowy Range not far north are mature Varnished Gums less than 50 cm high. Such variability makes eucalypts more a spectrum than a family. They merge species, change form, appear at widely separate locations. River Red Gum has at least three recognised varieties. In the Adelaide hills it and SA Blue Gum are distinct species, but the blue looks like a red which has climbed off the flats, and both look like Blakely’s Red Gum, a hill tree. Grey Box shades into ‘a chain of related species’. The same species can have different coloured flowers: Mugga Ironbark in New South Wales and several West Australian species can have cream, pink or red flowers. Near Bulli Pass (NSW) two mature trees stood side by side, one smooth barked like Sydney Blue Gum, the other rough barked like Bangalay. Both rose from the same root.70
How to classify a plant which does that? A Gippsland bushman did it by tasting the leaves, blindfolded.71 Others classify the bark. As a boy I learnt four bark groups: gum (smooth), box (trunk rough, branches smooth), stringybark (fibrous) and ironbark (hard, corrugated). Other barks include Blackbutt, Minni-ritchi, bloodwoods and mallees. The bark of the first eucalypt Europeans described, Messmate Stringybark, found on Bruny Island in 1777, is more ash than stringybark. The bark of two majestic species, Yellow Box and River Red Gum, seem equally between box and gum. Most puzzling, if its bark lets a species choose how to counter drought—smooth reflecting heat, rough shielding it—why do both smooth and rough barks grow near Australia’s hottest and coldest extremes? In other ways too eucalypts defy botanists, who now identify three genera, Eucalyptus, Angophora and Corymbia.
Another eucalypt trait is handy for historians. It chases light, even though Australia has plenty (pictures 1–6). Most plants seek light, but no tree so dramatically. In shade it grows straight, on a shade edge it bends and branches to the light, in light it sprints up to outpace neighbours, then spreads wide. From twigs to trunk its shape declares how much light it had in the past, where light came from, and if and when the light changed. Its shape thus reflects the conditions it grew up in. A history of its surrounds emerges, showing whether a locality was once open or forest, or first one then the other. As a rule, the wider the canopy, the more open the country was.
This history can be extended from locality to landscape by noting the spacing of each eucalypt generation. It is hard to decide a standing tree’s age. Growth rates vary, but locally this smoothes to an average, so trees growing under similar conditions can be sorted by size into generations. In alpine forest or mallee usually only one generation is apparent, but elsewhere several readily emerge. Even in dense forest they can be distinguished as easily as gums on the Murrumbidgee from the 1870, 1916, 1956 and 1974 floods. Each generation’s size and spacing announces its age and history, and so the history of the land around. Where scattered and wide-canopied giants tower over their straight, slim, crowded children, the country was open once but forest later. Where big trees stand straight and alone, branches hugging trunks, forest has been cleared.
Why isn’t a generation like its parents? Why are straight-limbed trees topped by wide-canopied elders? How could land be open in 1788 but forest later? Why within a few metres does one tree lean into the prevailing wind, another away, a third across? In open country why does one tree twist its branches in one direction but another doesn’t (picture 2)? To cause such things the landscape itself must have changed. Eucalypt shape and spacing are valuable guides to the nature of Australia. They convey what landscapes were like in 1788 and how they have changed since, provoking a central question: were they natural or made?72
Note 4. People could manage plants with fire.
Climate, soil and local moderators are compounded by a notoriously random constraint: fire. Fire is drought with legs. Many plants deal with both in the same way: they re-shoot or seed. Yet whereas drought is rarely a friend, fire often is. Plants relate to it so closely that it can group them. Species are fire dependent (needing fire to survive), fire promoting (encouraging fire with oil, resin or flammable material, often because they are fire dependent), fire tolerant (accepting fire), fire sensitive (killed by fire but seeding after it) or fire intolerant (killed by fire).
Fire dependent species include some near the hottest (Mitchell Grass, Spinifex) and coldest (Buttongrass) parts of Australia. Near both extremes Grass Tree trunks resist fire but rot without it, and fire generated the wonderful arrays of bulbs, tubers and flowers early Europeans saw. In settled districts this is uncommon now, but a year after the big 2003 fire Kosciuszko National Park had its best flower show for decades on ash and cleared ground. Without fire, shrubs and grasses smother these species before themselves becoming moribund, and even with fire, stock might eat or trample them out. But suitably timed fires can trigger species to regenerate (Yam Daisy, Bracken), or sprout from lignotubers (banksia, waratah, tea-tree, heath), or flower (Christmas Bell, Gymea Lily, grasstree, waratah, daisies, lilies, orchids), or germinate (Indigofera, bank-sia, hakea, heath and others with hard seeds or pods), or die but set seed (Mountain Ash, Mulga, many central Australian shrubs), while fire ash provides nutrients (Blady Grass, Bracken, heath) or activates soil bacteria to increase nutrient supply (Zamia). At the other extreme a few species, most in cold or wet areas where fire is uncommon, are killed outright by any fire (rainforest), and some which welcome cool fire die in hot fire (Budda, Yarran, Tasmanian pines, tropical open forest trees). Knowing how plants treat fire let people in 1788 manage them suitably.73
Note 5. Most wattles regenerate densely after fire.
Acacias have a range of fire responses, but most meet it with their drought defences. Some use lignotubers; most die or die back after releasing copious seed. Seedlings soon crowd the land. Mention in early records of dense young wattle may well mark country recently burnt, while sapling height can suggest how recent the fire was.
How much fire kills an acacia, and how hot it must be, varies greatly. A mild fire kills Mulga, Gidgee and Brigalow, though it rarely takes hold in Brigalow—its dense stands smother competition, it drops no bark, and it sheds leaves mostly during rain, so it offers little to burn. Some central Australian acacias tolerate fire, yet if the season permits, seed within six months. Others die but hold seed for years, waiting for rain. Such diverse responses often co-exist. In 1788 people fired acacias judiciously, conserving stands in different fire recovery stages.74
Note 6. Eucalypts and fire formed an ancient alliance, which people joined.
In one of Australia’s great alliances, eucalypts greet fire with astonishing ingenuity and diversity, encouraging, tolerating, resisting, deflecting, re-greening, seeding. Tropical eucalypts welcome fire far less than their southern cousins. They don’t drop flammable bark, their leaves carry less oil, they don’t hold seed for post-fire recovery, and few use buds or lignotubers, and those rarely. Yet they use fire, seeming to expect what they usually get, frequent cool fires which suppress competitors without damaging crowns. They dominate northern savannah.
Most southern eucalypts promote fire. From alps to desert they use their drought defences to help fire kill insects, mistletoe, fungi, soil bacteria and any plant in range. They don’t like competition. If understorey Blackwood, Black Sheoak, Sweet Pittosporum or the like becomes dense, even a hot fire, which most are in thick scrub, may not eliminate it, because the seedlings surge from the ash and capture nutrients. So most southern eucalypts encourage frequent fire. Normally this would mean cool fire because fuel can’t accumulate, but this might not destroy competition, so eucalypts make fires hotter. Their trunks resist fire, their open crowns fan it, their bark, leaves and oil intensify and channel it.
Barks vary, letting each species manage fire in its own way. On the tree most undamaged barks do not catch fire. They contai
n kino (gum) which resists burning. Ironbarks are tightly packed. A careless axe bounces off, and an average fire, finding no hold and no oxygen, merely licks the surface. Stringybarks offer a few loose strands to help fire up to the crown, then defend their trunks like ironbark. Mallees offer curling bark; Spotted Gum, Karri, Sugar Gum and others shed flakes. Desert trees like Ghost Gum and Lemon-flowered Gum have smooth white powdered bark which deflects heat and offers fire no hold. Mountain Ash has thin bark and almost any fire kills it, yet its leaves are the most flammable of all eucalypts, and it drops more litter than most. It recovers from seed, so needs fire to clear the ground and lay ash. If a fire comes it makes sure the fire is big and hot, for if no fire comes in 400 years or so it dies, and scrub chokes its seedlings. Most southern gum barks, Ribbon Gum for example, burn poorly when tight on the tree, well when loose, and explosively when dried, packed with toxins, and shed. Barks shed mostly in summer, when fire is most likely, and they become fuses, among the world’s most flammable forest fuel. Colonial cooks used the sudden flare to bake cakes, and in the right conditions the bark flies on the wind, starting spot fires 30 kilometres and more away. The bigger the tree the more bark it drops, so the tree both promotes fire and regulates how big it will be.
Leaves release volatile oil on hot days when fire is most likely, the scent flooding the bush. Leaves are evergreen, moulting all year. The tree dries and drops them, then waits. A spark catches. Leaves become candles, bark becomes fire bombs, crowns catch and fan updrafts, terrifying infernos race, oil-laden trees explode. Leaves and bark are torches for their own destruction, but the fire is hurried on, not boiling the sap and clearing earth and air. Competing plants are destroyed, trunk and branch sprout, the refreshed tree stands metres above any competition, capturing the food and the light (picture 5). In a nutrient-poor continent, this is a tremendous advantage. Allying with fire let eucalypts conquer Australia.
The alliance amazed Europeans. Breton wrote of
fires which prevail every year, for the grass being ignited, scorches the bark of the tree . . . It has often excited my surprise that even a single tree should escape from the tremendous fires which so frequently occur! The fire very frequently runs up the bark to the topmost branch, making the tree as black as charcoal; yet it goes on flourishing, although every succeeding year brings a recurrence of the same scorching, and, occasionally, twice in the same season: sometimes, indeed, the tree is destroyed, and nothing remains but a black and hollow stump. It often happens that a shrub, or young tree, is so effectually charred externally, that a person naturally infers it must have perished, but in the course of a few weeks it will throw out leaves.75
Or seeds. In some species seeds are the last resort, in others the first, but no eucalypt discounts seeds and almost all protect them in hard nuts. The seeds are tiny, often like powder, and seem impossibly vulnerable, but the nuts resist fire as efficiently as bark and oil promote it. They heat and cool quickly, then in ‘a miracle of timing’ shower millions of seeds into the rich ash below.76
Note 7. Erratic fire is the least, controlled fire the most, manageable of the variables constraining Australia’s plants. In 1788 fire-diverse communities grew comfortably together. This argues that most fires were managed. Understanding fire locally made management possible.
In 1788 plants with unlike fire responses were neighbours. Grass burnt every 1–4 years edged rainforest never burnt, open eucalypt forest cleared of undergrowth every 3–5 years gave way to dense eucalypt forest burnt at most every fifteen years. Tranquility Mintbush, a shrub of eucalypt–rainforest boundaries, germinates best after low intensity fire and neighbouring grass after high intensity fire, but neighbouring rainforest is killed by almost any fire.77 Kangaroo Grass shared land with tubers. Fire every 2–3 years lets the grass flourish, and over much of Australia in 1788 it was so dominant that fires must normally have burnt this often (too often for fuel to build up for raging bush-fires). Yet if fires burn every year the tubers die out in time, and if fires burn less than every three years the grass chokes them out, then itself becomes moribund.78 Central Australia’s most important plant food, Desert Raisin, dies without fire, but adjacent plant foods can be either fire tolerant (Bush Banana, Bush Plum) or intolerant (Fig, Quandong). Mulga and Gidgee die even in mild fires, and fires more than once a decade or so eradicate entire stands because no tree can flower in time. Yet both species grow among Spinifex, which needs fire every five years or so to flourish. In heathland too much fire creates sedgeland, too little creates woodland,79 yet Heath Banksia needs fire to germinate but is discouraged if burnt more than every 8–10 years and killed if burnt every 3–4 years.80 Across Australia, tuning to so erratic a constraint should sooner or later have made most communities vulnerable, yet in 1788 they flourished in intricate diversity. Clearly, erratic fire was rare and controlled fire normal (ch 6). This was no fluke.81
After 1788, some newcomers imitated 1788 burning, or thought they did, but most banned fire, which meant abandoning land to erratic fire. What happened speaks volumes for the precision of 1788 burning. Either bushfires increased in number, severity and extent, or fire sensitive species were favoured. Both transformed plant communities. By the 1810s John Macarthur’s land near Sydney ‘had become crowded—choked up in many places by thickets of saplings and large thorn bushes (bursaria spinosa) and the sweet natural herbage had for the most part been replaced by coarse wiry grasses which grew uncropped’.82 Across the mountains a mere two decades of grazing and fire suppression let unpalatable fire sensitive species like cassia, Budda, Yarran and White Cypress smother 1788 grassland.83 After 1860 the Cypress captured so much country that it became a major pest (ch 11). Had 1788’s fire regimes been natural, this change would have been at least less dramatic.
Fire let people select where plants grew. They knew which plants to burn, when, how often and how hot. This demanded not one fire regime but many, differing in timing, intensity and duration. No natural regime could sustain such intricate balances. We may wonder how people in 1788 managed this, but clearly they did. The nature of Australia made fire a management tool. No doubt some plants suffered during the learning centuries, and there are hints that there was more to learn in 1788 (ch 11). But with fire as an ally people worked the land as intimately as humans can.
4
Heaven on earth
All religions attempt two things: to explain existence, and to regulate behaviour. Aboriginal religion integrated these by assuming the spiritual parity of all life, and by subjecting every aspect of it to overwhelming religious sanction. This pivoted on the Dreaming, a word tolerably conveying the sense of timelessness central to Aboriginal belief. ‘The great and specifically Australian contribution to religious thought’, Ted Strehlow declared, ‘has been the unquestioning Aboriginal conviction that there was no division between Time and Eternity.’1 The Dreaming conceives an unchangeable universe, hence free of time. This can be so because the universe is not natural: it was made from darkness by God. Who made God and darkness no-one knows. They are as much puzzles as chance and death. No religion has solved them, but denying time makes them easier to pass over, and people accept that although it is worthy to strive to understand, they are not meant to know.
Across Australia the creation story is essentially the same: God made light, brought into being spirits and creator ancestors, and set down eternal Law for all creation. The creator ancestors accepted the Law or suffered if they didn’t, and made epic journeys across a formless space, giving land and sea substance and shape before settling to rest in a place important to them. They are there still, and where they went still bears marks of their trials and adventures. All things derive from their presence or deeds, and are ruled by the Law they passed on.
Since universe and Law never change, time is irrelevant, as in a dream. Change and time exist only as cycles: birth and death, the passage of stars and seasons, journeys, encounters, and after 1788 the appearance of plants and animals seeming new but alwa
ys there. Cycles are eddies, ending where they begin or eclipsed by larger cycles: travel by death for example, or seasons by life spans. Eddies exist not on a river of life, for a river has a beginning and end, but on bigger eddies, in a boundless pool. Time is an eddy; the pool is timeless. Pool, eddies and Law are the Dreaming.
The Dreaming has two rules: obey the Law, and leave the world as you found it— not better or worse, for God judges that, but the same. The first rule enforces and exists for the second. Together they let place dominate time, and translate well understood ecological associations into social relations—kin, marriage, diplomacy, trade and so on. They apply the same relations and obligations to all creation, guarding the universe by outlawing fundamental change, so making all creatures conservationist and conservative. In most other societies an urge for change is so entrenched as to be thought natural, nor is it clear that people entirely succeeded in leaving the world as they found it (ch 11), but they dedicated their lives to conserving what they inherited, and within the perception of living generations generally they succeeded.
The Dreaming is comprehensive, as you would expect of people with much spare time. It gives and explains a role to every part of creation, and decrees how each must act. This does not stifle human curiosity, but innovation and creativity become means not ends, eddies not the pool, and do not disturb a sense that the fundamentals of existence are beyond challenge or improvement. About 1838 Adelaide missionaries
took two Natives lately tattooed to their home, and spoke of the rite they had undergone (the origin of which is ascribed to a species of Red Kangaroo) endeavouring to shew them the foolishness of the practice and observing of Jehovah that he alone was to be feared and not the Red Kangaroo, for they believe the Red Kangaroos will kill them if they do not thus cut themselves.2 One of them growing angry said, why do you charge us with a lie, i.e. reject our opinion, we do not charge you with lies; what you believe and speak of Jehovah is good, and what we believe is good. We replied that only on one side the truth could be, and that was on our side. Very well, he answered, then I am a liar, and you speak truth, I shall not speak another word, you may now speak.3
