Environment

In Praise of Exotic Species

2014-jan-feb-coverWhich plants and animals should Australians favour? This question causes endless debate. Many people vehemently assert that native plants growing on a site are the best on that site for every purpose. One leader of the pack has been Tim Flannery, who in his 2002 Australia Day address suggested introduced plants like roses, plane trees and lawn grasses were a blot on the Australian landscape and should be discouraged. He suggested that among the 25,000 species of plants in Australia we should find superior replacements. Would we? How long and arduous would breeding and selection be? Such people say, “Surely it’s simple logic: they have evolved there and are therefore best adapted.” But did they evolve there? And even if they did, does that make them the best?

The answer to the question has important implications, not least in the use of land to feed the growing population of the world, both in growing food crops and in providing protein through grazing animals. The answer is particularly interesting in Australia, where accepting plants from elsewhere has been a hugely important part of wealth creation.

 

Can we define a native plant?

 

Again, many say, surely it is easy. It has long grown here, belongs here, must have evolved to suit this environment. But in fact we have no proof that even plants now dominant have evolved here. Perhaps the best we can do to define a native plant is, “A native is a plant that was here before us.” (And one can include Aborigines and Europeans under “us”, as in terms of the evolutionary time-scale of plants we arrived at much the same time.) That is all we really know for sure. It may have evolved here, but it may have arrived at any time in the more than 100 million years this continental land mass has existed. In any case, is presence at a site proof of superior adaptation over all other possible plants that have not been tested? There are many examples of the superb adaptation of known recent arrivals: all Australia’s jacaranda trees apparently developed from one introduction, and the coconut palm frequently and randomly floats ashore, having grown on many distant islands.

The same natives-are-best logic is used in places like India and South Africa to damn our eucalypts, which flourish there: it is alleged they use too much water, that native trees would be better. In fact, to give a certain amount of shade, that is, by having a certain leaf area, there is little difference between plants in their total water needs. A different issue is that some are more drought resistant. Because of their ability to survive and thrive, and provide good wood and honey, eucalypts could be considered one of Australia’s great gifts to the world.

Evolution of plants has gone on for millions of years, before the land we call Australia had the present shape and the current climate prevailed. (Yes, there has been much climate change.) Though we can only speculate, it is generally agreed that there was long ago a huge southern landmass comprising what is now Antarctica, South America, Africa, Australia and some nearby islands. A large mass apparently broke clear—we call this Gondwana—which in turn broke up to form New Zealand, New Caledonia, New Guinea and Australia. Plants were carried with these pieces and continued evolving, impacted by climatic and other influences, such as animal grazing, insect attacks and microbial infestations. Breakdown of rocks with their varying composition of minerals formed characteristic soils, and because plants vary in their tolerance of levels of minerals, soil type, too, influenced this evolution.

It is hard to know how much long-distance migration of plants there has been over time. Plants have a huge variety of dispersal mechanisms: wings that enable seeds to blow on the wind, awns that cling to fur and wool (and, once it was invented, clothing), flotation in running water. Having seeds attractive as food for an animal or bird, yet having some resistance to digestion, is a great asset, especially if the creature involved is a wanderer that can pass the surviving seeds some distance from the parent plant along with some manure to give any new seedlings a good start.

The classification of plants has been formalised over the last few hundred years, especially since the detailed studies of Linnaeus, who developed the idea of classification and descriptive Latin names.

Plants have evolved into many different forms. Early plants did not have flowers: we classify that lot as gymnosperms. The more recent evolution of plants to have flowers has given us the group we call angiosperms, the male parts forming pollen that is spread by wind and insects. Most are cross-pollinated, so each new plant is a new genetic entity—the basis of adaptability and evolution—but some are self-pollinating, so very stable in genetic composition, though less adaptable. Many plants, once seed is set, form seed covers and store a nice amount of carbohydrate and protein to give the new germinating plant a good start—and also become one of our great sources of food. Plants have been classified into orders, which have been divided into families, then genera, and finally individuals grouped into species.

The exact grouping for a species depends on the judgment of humans, some of whom have been eager to divide plants and so claim fame by naming new species. Properly establishing that a new species has been found demands careful exploration of existing collections in herbaria and the study of any closely related material, which all takes hours of tedious work. A well-known international television broadcaster once reported on a day’s visit to Gippsland: “We found five new species!” He may be a good broadcaster, but he is not a good botanist.

Another division of plants is into annuals and perennials. Annual plants begin from a new seed each season, while with perennials, even if seed is set, the old plant lives on for some years, even centuries. The perennial plant may survive by becoming dormant in adverse conditions, with buds bursting out into new growth when conditions are right for growth. Annuals often set huge numbers of seeds, which may have resistance to germination, such as dormancy or hard-seededness—thus surviving adverse conditions and often germinating in huge numbers when conditions are right for growth.

Many of our crop plants are annuals, but it has become fashionable to call for the use of perennials, arguing that there would be a saving of effort such as preparing a seed bed and sowing each year. However, the idea is a delusion. In modern zero-till farming very little effort goes into land preparation and sowing, and both annual and perennial crops would need the same weed control and nutrient additions. The main down-side would be that the farmer would lose the flexibility of changing crops in response to demand, or using new disease-resistant varieties. Further, yields would often be lower: an annual prepares to die by translocating virtually all of the nutrients in its stems and leaves to the seed. A perennial sets stores aside to live on through the adverse season, usually in basal buds and structures on roots, so translocates much less to its seed.

When conditions are right, seeds of annuals germinate, mobilising the reserves packed into the seed and growing rapidly: the capability of annuals such as barley grass to germinate, turn green and build plant tissue is astonishing. Tim Flannery has described such plants as having “weedy” characteristics. Rather, this is simply the result of successful evolution in areas with a long adverse season such as summer drought yet a definite seasonal winter rainfall ideal for growth. These are the characteristics of successful adaptors.

Gondwana has a special place in the evolution of our vegetation. It is often said that Australia, one of the largest of the Gondwanan land-masses, has ended up with a unique flora. However, it depends on definition. All of the main plant families occurring here are well represented on other continents, so most plants have cousins elsewhere, some far away. For example, wallaby grass, so widespread in Australia, is a close relative of the oats long used as a grain crop in Central Asia and Europe. The ancestors of one or the other must have moved or been carried.

How unique then is our native flora? The assertion is based on the fact that two well-known groups—the very large and prominent genus Eucalyptus (with some recently given other names) and the large-leafed subgroup of Acacia occur only in Australia or nearby (a few Eucalyptus occur in New Guinea). However, a comprehensive analysis of world distributions brings the assertion into question.

Northern Australian plants are closely related to the Indian and Malayan flora, so are probably immigrants from South-East Asia. The botanist Joseph Hooker suggested several eras of arrivals in the Cretaceous period (65 to 135 million years ago) as a result of land movements and sea level changes.

Of course, the genetic material present at break-up of Gondwana has powerfully influenced the flora on each land mass. Thus, though there were some brilliant-flowering legumes, like Sturt’s desert pea, on poor soils in dry areas, in the moister areas there was a dearth of legumes capable of prolific fixation of atmospheric nitrogen. Further, some of the soils were low in plant nutrients, especially the phosphorus that is so vital for energy transactions in living things. This was accentuated by the great age of the continent which meant much phosphorus had leached or washed into the seas, whence it had moved up through the food chain and been accumulated by bird droppings on islands such as Ocean Island. Once our farmers understood the need for more phosphorus, much of this has been returned as fertiliser. However, the lack of both phosphorus and nitrogen often meant poor efficiency of capture of solar energy, which is so abundant on this continent, and this made for some ecosystems with very stunted native vegetation. Paradoxically, some of the rather stunted plants evolved brilliantly coloured flowers—clothing the sand-plains of Western Australia and the Big and Little Deserts of Victoria in beautiful displays. However, low phosphorus and nitrogen limit the sequestration of carbon.

The flora of any place is, then, something of an accident of history, beginning with the genetic material present at the formation of the land mass, usually a break-up, or in the case of a large land mass, when barriers like deserts developed or there were depositions by lava flows. The flora present at European settlement of Australia was the result of such evolution, affected by those soils and that climate, occasionally with later arrivals. Thus it was the best that could evolve from the plant material that happened to be present in that set of conditions—but not necessarily the best that could ever be. Defining best is, of course, a complex matter. We humans usually relate it to utility: bearing much fruit or grain, providing a lot of leafy herbage for our animals, having brightly coloured flowers, producing timber.

New areas of soil such as lava flows as they cool and deposits from floods or even wind deposition of massive sandhills and plains can make an interesting study. What grows on these “new start” locations is just an accident of proximity. A good example was the treeless grasslands of the lava flows of western Victoria. Grasses spread quickly but eucalypts suitable to the soil type were slow to arrive: it took European settlers to find and widely plant a suitable eucalypt, the sugar gum, from western South Australia, especially Kangaroo Island and the Eyre Peninsula. They could almost have been accused of using an overseas species!

Sites having similar climatic conditions—for southern Australia this meant the Mediterranean regions—were the most likely providers of new plants. These regions were remote from Australia until bigger ships enabled long journeys. If the ships carried livestock and fodder, these lands were a source. A next important factor was modification of the soil or climate: cultivation, adding fertilisers, irrigation—all recent activities of humans.

The “arrival” of humans on Earth (if we can assume there was a defining moment) was geologically recent, coming after plants had been evolving for a very, very long time. Soon humans left their mark. (In a sense we define them as humans from the time when they began to leave their mark.)

Imagine a person—we’ll say “she” because women did so much of the food gathering—walks from the cave some distance over the hill and down along a valley, exploring. She sees a plant with a lot of fruit, picks some fruit, and it tastes better than any other she has tasted.

Being a thinker, she keeps the seed and uses her digging stick to bury it in the soil nearer to the cave, thus in due course a shorter walk to pick fruit. She is pleased, but the new plant is shaded by an existing plant, so she breaks off part of the offending plant. She and her family deposit faeces and urine on the earth near the plants, having noticed that this seems beneficial. Here is the beginning of plant selection, soil cultivation, plant propagation, pruning, and using manures, all in the cause of better value to humans. This is the beginning of agriculture, altering ecosystems, possibly grouping of plants.

These ecosystems—managed for human utility, including the one to which our gatherer had added new plants—could easily be described as both natural and agricultural. Was it unnatural of these humans to use their minds to think, and their hands to do things, to grow better plants, and have more varied food? There could also be benefit, or loss, when her new plant at its new site flowered and crossed with different plants, giving slightly different genotypes and possibly less seed down the valley. The possibility of variation does not alter the fact that her behaviour was natural.

Do we need to put a geographic limit on how far the “new” plant can be carried and the spread still be called natural? Some people want to put a limit on genetic difference in breeding too. And must all movement of pollen or seeds without human handling be natural if by birds, but not if carried by humans? An interesting example is the long trade routes like the Silk Road from China to the Middle East—passing through areas of great evolutionary significance—with plant material carried, both deliberately and accidentally. Someone would soon have done deliberate trade in new varieties known to have better taste or resistance to attack by insects or fungi.

In the last 500 years agriculture has become more and more complex. Especially in the last fifty years farming has become much more precise—exact measurement, awareness of plant nutrition, of chemical dangers as well as benefit, and so on—based on a profession called agricultural science. Modern humanity does not select a plant only from down along the valley—the search is global. New plants are “composed” using special plant breeding techniques, reaching to remote biological entities on other branches of the evolutionary chain for special genes. A great example is the merging of bacterial genes into cotton to give resistance to boll weevils, saving a huge amount of chemical application. Finally, while a single plant is just a plant, sensible arrangement into a cluster is an orchard or a crop. Modern humans use machinery to sow many seeds of the selected new plant to maximise yield per unit area of land or of human or mechanical energy.

Soils vary enormously. Eroding streams tend to gather material from a range of rocks and, downstream, may lay down deep soil, creating fertile land. Paradoxically, severe erosion upstream means deposition of large areas of soil downstream. We define fertile as having an adequate supply of the sixteen elements needed for plant growth, such that it will supply several crops in succession. Slash-and-burn farming, as practised in times past in parts of Central and South America, was a way of releasing plant nutrients and getting several crops, then moving on. In other places, from early times efforts were made to return all possible residues—plant remains, animal manure, even human excrement—to the growing site, thus deferring the impact of deficiencies in the soil. Where the soil was very fertile, or where there were additions through soil deposition (as along river valleys and flood plains) or further breakdown of rocks, yields might be maintained over many years.

Progress in maintaining or even increasing yield with successive crops came with the scientific revolution: precise definition of deficiencies, amounts needed of any deficient elements to be added to maximise yield, and the timing of any application. Included in the models to define these things is information on soil moisture availability.

In most commercial farming every possible thing is known precisely, while organic production is still to a large extent “hit and hope”. The yield of crops under organic systems is, as a result, generally about 70 per cent of that attained with precision systems. Further, some of the vegetable matter added as organic “fertiliser” comes from land dedicated to the purpose of growing that vegetable matter, so the overall effect is to make organic land use about 50 per cent efficient. Given that the amount of energy input is related to area sown, rather than ultimate yield, about double the energy per unit of production is involved, so there is a serious question of higher greenhouse gas emissions per unit of food under organic systems. Fortunately, despite its publicity, organic agriculture is a small player in world food production, variously estimated as around 1 per cent of the farmed area in the developed countries of the planet. Every increase in its area reduces the planet’s ability to feed a growing population.

Australia eventually received some human migrants—two groups in just about the same geological moment: the Aborigines from the near north about 50,000 years ago, and people from Europe 225 years ago. At the time of Aboriginal arrival, their society was more developed than that of most other parts of the world, including Europe, but by the time the Europeans came to Australia there had been huge developments in other societies. Agricultural ecosystem management and plant introduction had become firmly established and accepted.

The Aborigines eventually spread to the bounds of the continent but the extent to which they interacted with the ecosystems is a moot point. They would have dwelt (and hunted and gathered) more in the locations where there were more assured water supplies and accessible game. They certainly accepted impacting on ecosystems, developing management systems, for instance, burning grasslands to improve visibility and expose regrowth. This was especially so near sites where kangaroos and other game came to water; managing kangaroos for meat this way was what we would probably now call a sustainable system. They must have recognised the part burning played in preventing grasslands from evolving into woodland or forest, at the same time increasing green shoot production from grasslands after rain, though they might not have defined the other benefit—more rapid recycling of plant nutrients. These activities were classic cases of management of natural ecosystems, with these benefits, yet having down-sides such as reducing soil organic matter. In more “knowing” systems both would be quantified and suitable amelioration devised.

As is the case with hunter-gatherers, the point of balance between the food needs of the total community and production is difficult to comprehend, especially over vast areas of land and variable seasons. Authors such as Bill Gammage claim that the Aborigines exercised management control over every bit of the land mass of Australia, but with their modest population this would be an impractical and unrewarding task. Gammage does suggest that care did not always mean action: people might leave land alone for long periods. In long droughts there could well have been catastrophic ecological events, and much human misery. That the Aborigines did not develop a form of agriculture in some of the well-watered parts with fertile soil is something of a mystery. There was apparently some local plant cropping near Geraldton, and fish trapping was organised in western Victoria.

Gammage also makes some curious generalisations about the soils, suggesting that under Aboriginal management they were nice and spongy but lost this quality after European settlement, leading to vegetation changes. No doubt there were changes in the areas that felt the impact of the plough—less than 10 per cent—and some effects of the tread of sheep, though the close grazing of the rabbit (with the softest tread of all) possibly had greater impact on vegetation. Locally, the influence of frequent firing probably had the greatest impact—on the down-side destroying organic material and on the up-side releasing and circulating nutrients.

Gammage is one of a number of authors who have pointed out that Captain Cook described some landscapes as open woodland, that is, scattered trees over grass, yet, as far as could be judged viewing from the same spots today, these areas are shrubby instead of grassy. Gammage asserts that “typically, grass grew on good soil, trees on poor”, a gross over-simplification. There are many factors involved: for instance, the western plains of Victoria were grassland because their formation from lava had been so recent that suitable trees had not yet arrived or thrived on new soils. Grasses have much faster dispersal.

There is plenty of evidence of plant migration, ecosystem regrouping, producing different vegetation over time. Take the case referred to earlier of the sugar gum, one of the few eucalypts which readily adapted to the basalt plains of Victoria. At the time of European settlement it occurred on Kangaroo Island, on the Eyre Peninsula, and in the Flinders Ranges. We can speculate whether this was the residue of a very wide occurrence or the result of slow dispersal from a small area of evolution. Either way, adaptability to certain soil characteristics is likely to have been a factor.

Commentators on vegetation need to have a background in plant ecology, asking why, when and where, not simply be describers of what is now. The Adelaide School of Botany, led in the 1940s and 1950s by Professor Joseph Wood, produced some great analysts in ecology: Crocker, Specht, Coaldrake. The Soils Division of the CSIR was established in Adelaide and so the powerful ecological influence of soil variations was studied there.

Much of their work explained ecological change without the European influence. Crocker reached back in geological history in a seminal paper, Post-Miocene Climate and its Effect on Pedo-Genesis in Southern Australia. An extraordinary coincidence was the arrival from England, hoping to be cured of tuberculosis, of James Black. In his then successful life as a journalist and author, and using his inheritance from his sister Mrs D’Oyly Carte of Gilbert and Sullivan fame, he produced Black’s Flora of South Australia, a wonderful aid to plant studies which ensured that the classification of plants was standardised, an essential for good ecological work.

The Europeans came from what was not only an agriculturally developed economy, but by that time a rapidly evolving society, with a surge in the use of science and technology. Making a new Europe may have been in their minds to some extent when choosing food crops—logically, familiar fruits and grains. In due course, plants such as wheat were “localised” by selection and ultimately, breeding. Settlement inland by the Europeans emulated much of the Aboriginal system: grazing animals (sheep) on the kangaroo and wallaby grasslands for meat and skins or wool. They saw fire as a hazard to their fixed structures, so in contrast to the Aborigines they avoided widespread burning, so unknowingly increasing shrub and tree growth and reducing grassland. Despite what some apologists say, less burning of plant debris would have allowed more organic matter to accumulate and so benefited the structure of the soils—they were likely to become spongier. Later, where land was to be cropped, burning, axing and grubbing were used to eliminate regrowth of native shrub and tree species, and considerable areas of ecosystems, some recent, some long established, were cleared and cropped—and had lower organic matter, were less spongy.

The land left as grasslands at first seemed moderately productive, often carrying one sheep per hectare. In due course, legumes with a capability to copiously fix atmospheric nitrogen arrived from elsewhere and, given the right fertilisers, this meant substantial increases in everything: herbage production, numbers of grazing animals (up to ten sheep per hectare), soil organic matter, carbon fixation, water infiltration—and prosperity. In passing, we should also note that this was a grand sequestration of carbon!

Many people consider any partial or complete replacement of existing vegetation to be against nature. However, plants developed elsewhere have often flourished, becoming more useful than natives so either complementing them, as with grasses, or replacing them. And in any case, the environment was changed by new activities, especially the adding of fertilisers and control of grazing by fencing.

Some people ask: Why use introduced animals such as sheep and cattle, rather than the ones that had evolved here and were well suited, such as kangaroos? The answers lay with both groups of animals. After centuries of breeding and selection and training, sheep fitted well with the life and needs of humans, so, as well as being easy to manage, they provided meat and skins and even milk. Kangaroos were incredibly advanced in evolution: though only breeding singly, the adaptation of one young at foot, another in the pouch and another fertilised ovum in the womb gave for rapid multiplication after harsh times—and add in the re-absorption of the foetus if the new season did not deliver its promise. Lastly, their locomotion by bouncing, rather than running, enabled movement over long distances and leaping over obstacles which made it difficult to muster and contain kangaroos. In contrast, docile sheep were easy to contain and sort—and kill.

A twelfth-century monk once wrote that God created sheep first of all animals because a sheep flock would have enabled humans to survive by providing most of their needs: skins for tents, meat for food, milk to drink and make cheese, fat for candles, wool for clothing, ropes and thread, bones for tools and needles, horns for handles, skins for holding water and wine, and lambs for pets.

The Mediterranean climate has a long history of human activity, with the climate well understood: the hot dry summer and usually fairly moist winter, but tapering off into desert. It is not widely understood that Australia provides a high proportion of the land on the planet so described. In the Mediterranean itself at that latitude much is sea. In North and South America the same locations are limited by high altitudes, and South Africa has little land in that latitude. By contrast, in Australia there is a wide sweep across Western Australia and quite an area in South Australia, while much of Victoria, though not exactly conforming, has strong elements, like a definite winter season and considerable rain. Scattered around the globe as these remnants are, and with oceans and tropical climates in between, there was little likelihood of natural spread of plants from one to the other—even bird carriage over such a distance was unlikely. However, once human boat trafficking carrying livestock began, many ships called into Mediterranean ports to load fodder, which often contained seeds of plants from the lands around the Mediterranean Sea. Some plants made landings across southern Australia, and found it climatically suitable for their growth. One notable arrival was subterranean (sub) clover, which had evolved on acid soils. Such soils were not common in southern Europe, but southern Australia had vast areas of acid soils, so there was huge potential for spread.

Now that we understand the physiology of these plants, we recognise some fascinating quirks of plant ecology. Once germinated, the clover plants need to “accumulate” some cold before the plant stops producing leaves and flowering is initiated. This change is attained in less time in Europe with very cold winds from the Arctic over land compared with milder southerlies of Australia—over sea from the Antarctic region. Thus sub clover in Australia has a longer leafy period, so is a prolific herbage plant in the fields rather than the stunted roadside weed it is in Europe, fixing proportionately much more nitrogen. Further, the seed is set into a spiny burr, so with the widespread grazing of sheep, animals that lie down a lot and have woolly coats and often rub on trees, seeds spread readily. Widely sown in the early to mid-1900s, this plant has fixed between $5 billion and $10 billion worth of nitrogen each year depending on the season: its arrival was arguably one of the most important single economic events in the history of Australia. This classic case puts down forever any assertion that plants evolved elsewhere are not suitable to Australian conditions. Many other new arrivals have also proved to be useful.

Prosperous farming industries were built on a readiness to modify natural ecosystems using new plants (especially legumes to fix nitrogen), defining and remedying any nutrient deficiencies and deliberately controlling animal grazing. This maximised their interception of solar energy and incorporation of carbohydrates into the pool of biological carbon. Growing well-chosen plants was repeatable, comparing favourably with mining, which can be done only once.

 

Changes in an ecosystem

 

Some people believe change equals degradation; some say change indicates the ecosystem was unstable—but surely it might just be that it was highly adaptable.

It is fashionable to assert that Australia is too dry and the soils too old for agriculture, implying that settlers should never have tried to change ecosystems to give fruitful outcomes. In fact selection and breeding of cultivars and agronomic processes to conserve water have enabled productive ecosystems—crops—to be established over vast areas of semi-arid country (as I described in “The Greening of the Arid Boundary” in Quadrant, July-August 2011). And a small percentage of Australia isn’t dry, so because it is a big continent, this is quite a large area. Furthermore, because of its geography—wide east-west facing the South Pole over ocean—the wide coastal fringe, though receiving moderate rainfall, has a better spread and more reliability than comparable areas elsewhere in the world. And not all our soils are poor—the river valleys and flood plains of the Great Dividing Range and the volcanic soils make up quite a large area. In any case, improving poor soils is a simply a challenge for scientists and farmers.

Those who leap to the assertion, popularised by Tim Flannery in his book The Future Eaters, that to change an ecosystem equates with its destruction have not stopped to analyse human history. They do not recognise that human interaction with ecosystems—as our prehistoric woman did—is a natural way of adapting, aimed at, and frequently achieving, improvement for human utility.

Allied in the minds of these critics is the view that the move from hunter-gathering and the beginning of sedentary lives, which came to be called farming, was the beginning of the end for the planet. Such people see farming as always exploitative, not allowing the healing as did the allegedly gentler hunter-gatherer. In fact, modern farming can be restorative, even productivity-building. Logically, although farming was initially grasped as simply a more certain way of ensuring an adequate food supply, commercial farming with surplus for sale has always intrinsically had the general objective of at least maintaining, and hopefully increasing, yields. It pays! The emphasis on the notion of sustainability in the last few decades has been helpful in emphasising this. At the same time, the search for fixed systems is a delusion—the readiness to note adverse elements and have solutions adopted must go on and on.

The story of the cropping areas of the southern part of Australia, where very little of the land is less productive (or has lower carbon) than when Europeans arrived, illustrates this. Most of it is now much more productive, and has more carbon. Turning the farmers into legume lovers has meant much more nitrogen being available to combine with carbon and phosphorus in the soil—sequestration of carbon. (What if urban people became legume lovers too and insisted on a legume—peas or beans—as their preferred green vegetable over others that need artificial fertiliser nitrogen. What a contribution this could make!)

Thus under farming there have been huge changes, much of it the inexorable march of evolution albeit speeded up by these intelligent, technically able mammals called humans. This has sometimes led to complete replacement of the “natural” ecosystems, resulting in huge multiples of productivity.

This continuous search for improvement is much more challenging than simply aiming for no change. Imagine how much simpler it was for the Aborigines—and how powerless they were. They saw the land and its coverage as a simple, fixed, gift of their gods. There was little or no new arrival of plants or animals. Climate was a given—no forecasts and measures such as food stores or grazing management of animals to handle adverse conditions. Soils were accepted for what they were, and there were no agronomists with new technology. Just a few kangaroos and low population growth, largely through higher and earlier mortality. Perhaps, after thousands of years, they were close to sustainability. A European settler arriving and choosing to farm faced awesome challenges, but eventually gained increasingly powerful tools, better and better science, greater resources—and now a responsibility to help feed the world’s growing population. And most of all, rejecting any notion that native is best, but rather, accessing the worldwide range of germplasm.

There are some dilemmas. In places like Europe and Australia a key objective in managing swards of pasture was to maximise growth and animal production, and in recent times, optimum sequestration of carbon. The Serengeti ecosystem of Tanzania, in its natural state, carries a million gnus and wildebeests. The herds eat out certain areas, not pushing on until there is just about complete baring of the soil. In Australia we have known from early research that grazing to leave a certain amount of leaf can markedly increase production. This would be possible in the Serengeti if areas were fenced. It would be surprising if the existing pasture species could not be improved by breeding or selection or new plants introduced from elsewhere, especially legumes that fix more nitrogen and produce much more biomass. Perhaps there could be some fodder conservation, even if only to allow some grazing areas to be set aside and rested. If the region became a production system rather than merely a tourist curiosity, livestock production might well be increased four- or five-fold, and animals could be sold for meat production, even export. Of course, if nutrients were exported, fertiliser application to remedy any limiting factors would be necessary. Given the same impact on productivity of such measures in native grasslands as has occurred in Australia, the people of some parts of Africa might no longer need aid.

Conversely (and perhaps a little perversely!) let us imagine that the Europeans settling in Australia had heeded an earlier “Flannery” and eschewed the introduction of species from elsewhere, had not considered the possibility of soil improvement or fertiliser application, and had allowed the animals to work out their own version of grazing. The residents of Australia and their descendants might well be grateful recipients of aid. Perhaps we were fortunate that for the first Europeans in Australia there was no “tradition”, but rather, an interest in new species of garden and crop plants, in identifying limiting factors for plant growth and remedying them, and a recognition of the need for innovation and change.

Sadly, so many of the good-hearted folk who go to help the Africans, while allowing some change, constrain it in the direction of “native is better”, traditional methods, no chemical fertilisers, locking the people into food shortages, even starvation. The Australian Soils for Life people suggest we learn grazing management from the casual, low-input operations in East Africa, on the grounds that they are working with nature—thereby implying that Australian farmers aren’t!

Land managers must focus their human abilities and strengths on intelligently and responsibly making a future, recognising the human and biological resources of the whole planet, constantly evolving new and more productive ecosystems. Wherever we are working to sustainably improve the productivity of ecosystems we must not be blinded by prejudice. We should accept the full range of plant material, evaluate new things and efficiently incorporate them into management systems. The more we make agricultural ecosystems productive, the more space we are able to set aside as parks and reserves.

We must use the full range of our tools and resources: we must be future makers.

Dr David F. Smith AM is an Australian ecologist who has studied a range of ecosystems around the world, some natural, others modified for specific human benefits. His book Rain & Shine: A Simple Guide to How Plants Grow was published in 2012 by Connor Court.

 

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