The way water moves across the Australian landscape or seeps into it, is wholly determined by the cover of vegetation, and on the condition of the soil surface of landscapes.
The vegetation is driven or powered by the energy of the sun, its volume or mass governed by rainfall, temperature. The level of cover is now determined by human actions or what we like to call ‘management’. Human management in the age of consequence is about trying to capture more of the photosynthetic product of the landscape. It is this desire that has driven agriculture, and human populations.
The paddocks I walk through on my thrice-weekly odyssey to the top of Mount Canemumbola provide lessons on which my mind muses. The walking track goes through a never-cultivated-by-humans piece of land, out of the gradual upward slope of which rises the resistant-to-erosion, volcanic mount Canemumbola.
A mountain knows through the slow ebb of time that it will one day be a flood plain. The vegetation on the track I walk is not in the same state as it was when Europeans, mostly Irish people, began to settle here from the early 1820s. There is certainly the Box Gum Grassy Woodland, although Kangaroo grass is only seen in a couple of small patches among the rocks on the sides of the Mount. There are some of the native daisies and other forbs and lilies that appear when conditions suit them. Unlike most paddocks where stock are grazed in this area, there are young trees growing here, the progeny of the eucalypts that are scattered through this paddock that has long periods without stock.
This year the paddocks beside the track I walk have lush grazing oats crops in them. This has been a very good autumn and the farmers had their crops sown early in March. The often-chancy Autumn rainfall came in a few well-timed falls that led to the crops being so lush. Today the freshly-marked lambs and their mothers are on the crop. Stock prefer diversity in the pasture, the monoculture crop does not suit them, it is too much of a good thing, full of more protein than their gut can process; it usually makes them scour until it is grazed down to the point where the high nutrient leaves have been grazed off and the more fibrous stems of the leaves give a bit more balance and the scouring stops. The farmer, either consciously, or through experience has recognized the sheep’s preference for more diversity and has kept the gate open to the track paddock that has a more extensive variety of plants from which to choose, as well as some dry material from the Spring of 2016. The sheep were almost all in the track paddock, they instinctively know what they like.
We are currently gathering firewood to feed the fuel stove that cooks our food, heats our water, and via a series of thermostatically controlled hydronic radiators, connected to the water-jacket surrounding the firebox of the stove, heats our home. We only cut wood from fallen branches or dead trees whose roots have taken possibly a hundred years to decay to the point that they have come down in a storm. Fallen dead trees, that have big hollow pipes, caused by termites, are important habitat for a large range of species, such as longicorn beetles, centipedes, johnny hairy legs, lizards, snakes, bats, bees and many species of fungi, those important agents of recycling that have the capacity to invade the wood structure of a tree weighing perhaps twenty tonnes, and begin the task of returning the nutrients in that massive structure back into the river of life. So if a tree with these features falls down we will not use it as firewood to keep us warm, but leave it for all the myriad of creatures who can find their home and food in or beside this fallen giant for maybe two hundred years. Standing dead trees are valuable habitat for many species of hollow-nesting birds, probably hundreds of species of insects and spiders, lizards, snakes and bats, to say nothing of the soil biota and fungi that gradually process the structure of the tree and return it to the river of life. In the brittle environments of Australia this can take hundreds of years. In the fire-prone environments of this country it is likely that fallen trees will be oxidized by fire before the weathering and intermittent biological processes of decay have finished their work. In a more humid, non-brittle tending environment the rate of decay of large structures like trees is incredibly rapid when compared to the glacier-like pace of the breakdown of a giant from the once abundant box gum grassy woodland that once covered a great sweep of country west of the Dividing range from southern Queensland in a great arc through NSW and Victoria to South Australia.
Our wood-gathering is another example of the human effect of accelerating natural processes. Aldo Leopold wrote an essay on the demise of the passenger pigeon from the big forests of the United States and Canada last century.
‘ The pigeon was a biological storm. He was the lightning that played between two opposing potentials of intolerable intensity: the fat of the land and the oxygen of the air. Yearly, the feathered tempest roared up, down, and across the continent, sucking up the laden fruits of forest and prairie, burning them in a travelling blast of life. Like any other chain reaction, the pigeon could survive no diminution of his own furious intensity. When the pigeoners subtracted from his numbers, and the pioneers chopped gaps in the continuity of his fuel, his flame guttered out with hardly a sputter or even a whisp of smoke.
Today the oaks still flaunt their burden at the sky, but the feathered lightning is no more. Worm and weevil must now perform slowly and silently the biological task that once drew thunder from the firmament’.
Australia is not dissimilar in area to the United States. Yet it supports fifteen times our population. 25 million compared to 300 million. This is because, while the central parts of the Australian continent are mostly desert with very limited surface water, intermittent creeks and rivers that are mostly inward draining, no forests or big rivers; conversely in the central area of the US, water is abundant, the glaciated soils are young and full of nutrients because only 18,000 years ago it was covered with a mile or more of ice, that stripped off the old soil and ground up the country rock, leaving, when the glaciers retreated, young, rich, new soil. The rivers in the US are big because they are full of melting snow pack from the Rockies, where our rivers rely for their flows on rainfall and run-off.
Whilst our central deserts are dry, they are not sand deserts, like the Sahara. They have incredibly diverse flora and fauna, reptiles and insects. The better-watered parts of Australia, mostly a green coastal fringe and the closer-in western slopes of the dividing range, have felt the heavy hand of agriculture, grazing and cropping. Whilst the rainfall should make them able to support more diversity of life forms than the desert country, agriculture has led to huge losses of biodiversity, so that we have this paradoxical situation where the deserts are more diverse than the better-watered areas. Where agriculture exists, the native grasses and forbs have been replaced by exotic species. This happened within only a few decades of European settlement.
We build dams on our farms, big dams on our rivers. The driest inhabited continent on earth captures these scarce waters to make an irrigation industry possible. We sink bores into the underground aquifers and when the shallow aquifers begin to diminish their yield we drill deeper. Meanwhile our soils, the largest potential water stores we have are limited in their capacity to store rainfall, leak it slowly to underground aquifers, and supply base flow to creeks and rivers as well as act as a storage buffer against drought.
How can this be? Our soils, whether used for grazing or crops have 70% less organic carbon, than when European agriculture began. This limits its capacity to store water, the two greatest assets we have, soils high in organic carbon, and water, are limited by our actions. Exploiting soil organic carbon has long been a pathway to profit in Australia. Another effect of lowering soil organic carbon is to increase the rate of runoff. Thus our low rainfall is less effective, we lose much of it that should be replenishing reserves and being stored in soils for the benefit of all life.
The energy that drives the reaction of photosynthesis makes it possible for plants to manufacture their own food and thus support the entire array of species that inhabit the green mantle of the earth. (There are a few rare exceptions to this). Life makes the atmosphere friendly for life, regardless of circumstance this has held for 3.7 billion years of life on earth. Diversity is the earth’s way of protecting itself from shocks, earthquakes, volcanic eruptions, storms, floods, fires and droughts. And yet the very essence of modern agriculture gives us the opposite. It delivers ecosystems whose diversity is falling away under the heavy feet of modern high energy agriculture. We deal in monocultures or very limited polycultures that have their genesis in death. Agriculture has its origins in the death of all species that might limit our desire for energy in the form of food rich in carbon. In the last two hundred years we have tapped the high carbon resources of the earth with frightening rapidity. Timber, soil humus, coal, oil and gas. These ‘resources’ have their origin in photosynthesis driven by ancient sunlight. We are burning them, like the passenger pigeons, in an uncontrollable blast of life. 370 million years ago these carbon rich coal oil and gas stores were laid down over 50 million years of life. Now we have combusted more than half of these stores in 200 years. That is 250,000 times faster than they were formed. Why does that not seem like an emergency for humans?
The only positive reaction in my mind that I can conjure today, is in the extraordinary capacity of the earth to keep renewing itself.
Observing the results of human behaviour in an age of consequence is a paradox. On the one hand there are the extraordinary benefits we have gained through our ability to enquire and try to understand how the world functions. From the gradual advance in scientific knowledge we are freed from the hard life our ancestors knew as the norm. The paradox is that what we have gained has imposed a terrible and never brought to account cost, on the living systems of the Earth.