Tuesday, 14 July 2009

UNDER FOOT: An Ecology of Lawns

There's a unique feeling of betrayal being the first to mow your lawn in the spring. Slowly the flat, matted mass of grass has stirred itself and reached to heaven till it can be ignored no longer.

But to be the first who heeds the call is not to endear yourself to neighbours who drive past as you decapitate the winter crop. The feelings of disapproval are palpable. You imagine the nudgings and promptings of the non-mowers in the cars."... which reminds me, isn't it time we cut our lawn?" It's a royal plural, but the grunting work will be peasant singular. And - gender equity notwithstanding - usually masculine. Hence the dark looks from my fellow males. I try to keep my eyes down.

But if the mass of living things found in the grass could look at me darkly they would too. Their tangled jungle is being brutally clear-felled. A wolf spider turns from hunter to hunted; a sleeping hawk moth flutters into life barely in time; there is mass exodus before the roar of the rotary mower.

The rotary lawn mower is Australia's gift to the backyards of the world, able to cut tall poppies with nationalistic indifference. Invented by Mervyn Victor Richardson in the early 1950's, he modestly patented the name "Victa" for it. Between the rotary mower and that other great Australian rotary invention, the "Hills Hoist", Australia has the backyards of the world marked out and tidied up.

Yet there is a futile territoriality about lawns. They are meant to tell something about us; certainly to say "this is mine", but also to display something of our command over nature. Lawns had come to prominence in Europe during an era in which the garden, for the rich, was the place to display the manipulative brilliance of human intelligence. Hedges, shrubs, and even trees were also shaped with this illusion in mind.

The property illusion created by lawns was taken to an amusing extreme by 18th century English landscape gardener William Kent, who frequently employed the "ha ha" fence. This consisted of a trench in the lawn at the boundary of the property. The trench could contain a stock-proof fence, but because it was hidden from view, the illusion of expansive holdings was maintained, even when the actual acreage was modest. Ha ha indeed!

Nature too laughs at our lawns, for grass provides only a Claytons mastery over our local environment. Even the best kept lawn is shared with hundreds, thousands, millions of crawling, creeping, flying, digging, sprouting, budding, living things, whether we know it or not. Try missing a few weekends of spring mowing and you'll soon see.

Still the illusion of ownership runs deep. I transgressed such a boundary as a child in Sydney. It was the drama of a cicada's death that made me forget myself. The insect called in alarm as a bird made a first unsuccessful snatch at it. The cicada was what we called a flowery baker - a large mottled brown and cream insect popular as a collected specimen. Firmly on the cicada's side, I followed as the bird made a second, this time successful pass. On the lawn in front of me the living, flapping, singing insect had its abdomen removed and ingested by the bird. The rest was discarded like a nut shell; a shell with face and wings and still-moving legs.

As I moved closer to confirm the grisly sight, a loud harrumph startled me. A woman was standing on her landing, rake held like a stave, a fierce and outraged look in her eye. It was only then that I saw I was on strange territory - her lawn. Knowing it would sound lame, I still wanted to tell her about the cicada; how its seven years beneath the ground had ended like this; how its passing seemed worth marking. But her look gagged my explanation. It was simplest to turn and run.

On other childhood days we would seek out the shilling-sized holes in our own lawns and flood them to try and bring the cicadas out. We reasoned that all those years in the nymphal stage wouldn't be hurt by staging a bogus summer flood. And up they would come like spirits from the grave - scarcely in the same form as the creatures they would become. A stiff but sodden brown caul held them prisoner still. Yet given time and careful handling they would dry out and soon begin their amazing metamorphosis. We would never tire of this unveiling, fascinated as much by the metaphysics as the physics, even if unable to articulate it. When it was all over we took the empty shell as a talisman.

In Tasmania our lawns are more subtly pocked by moths, but with a far greater impact. Moths are a winged metaphor for the power of fragility. They neither rip nor roar, yet their presence in the history of decay ranks with rust and Attila the Hun. Helen of Troy may have had the face that launched a thousand ships, but moths have the wings that tattered their sails.

Two ghost moths of the Oncopera species have Tasmania's grass divided between them. They are better known at their larval stage as corbie grubs, or just corbies. The winter corbie (Oncopera intricata) is more common in the north and north-west of the state. As a moth it is small - about march fly sized - with an unassuming mottled brown appearance. It is the larval stage of the moth that is notorious. During winter and spring the grubs of this innocent-looking moth come out at night to feed on grass. Patches of dead pasture and telltale vertical tunnels are the giveaway. They are so prolific that pasture damage has an economic impact.

Another small moth, Oncopera rufobrunnea - commonly called simply "corbie" - has an impact that is better known to the lawnmakers of southern Tasmania. Again it is the larval stage that causes the damage, hatching in our lawns as winter days lengthen into spring. Just how prolific they can be was discovered by a lawn-proud friend who offered his children ten cents a grub. A few tubs of water and detergent later they had relieved their father of nearly $50.

Australians are not the only people to be obsessed with neat green lawns. Czech playwright Karel Capek, writing in the late 1920's, chronicled the same kind of fixation among the gardeners of Prague.

As for us, owners of small gardens in town, please do not think that one dewy
morning we shall whet the scythe, and then with open shirt, with powerful
rustling sweeps, and singing popular songs, we shall cut the sparkling grass.
Things are rather different with us. First of all we want to have an English
lawn, green like a billiard cloth, and dense like a carpet, a perfect lawn, a
grass plot without blemish, turf like velvet, a meadow like a table.

There is a comforting familiarity in Capek's unfolding account of his lawnmaking efforts, found in his delightful but out-of-print classic 'The Gardener's Year'.

Well, then, in spring we find that this English lawn consists of bald patches,
dandelions, clover, clay, and a few hard and yellow tufts of grass. When weeded
all that's left is a waste land, trampled, and as bare as if bricklayers or a
herd of zebras has been dancing on it. Then it is watered and left to crack in
the sun, after which we decide that it really needs cutting.

There are many other ways to create holes and bare patches in grass. Its green sward is subject to attack from claw, fang, hoof, tooth, turd, mold, micturition and much more besides. At home our grass becomes the community noticeboard for the territoriality of mammals. Dogs and possums both scratch marks in the grass, telling others of their species how large, strong or virile they are. Dog urine is another notorious patch-maker. An overdose of ammonia quickly yellows then kills grass.

Other lawn holes have other causes. The introduced blackbird (Turdus merula) and the native White's thrush (Zoothera dauma) have similar aims in making holes in the lawn. Both are searching for earthworms and grubs. Having seen them at it often enough I'd thought an unusual frequency of holes in my grass was their doing.

But the shape of the holes was wrong. A blackbird probes a very small hole, only enlarging it if the prey is large or stubborn. The holes in question are all large, a few centimetres deep, about the same wide, and distinctly conical in shape. The scats (droppings) behind a few of the holes help to identify the culprit. It's the work not of a bird at all but of a native mammal, the eastern barred bandicoot (Perameles gunnii). This small insectivorous marsupial is considered rare and vulnerable in mainland Australia - with only a few established colonies in western Victoria. In Tasmania it is plentiful enough for some people to complain about the pasture or lawn damage it causes. To me it is a privelege to have their holes in my lawn!

It is one thing to know bandicoots are about, another to actually see them. The presence of an introduced grass helped me here. Though most of our grasses are immigrants, one that is no longer welcome is pampas grass. This hardy and invasive South American grass grows into enormous clumps that can spread into the bush.

But removing them is no light work. After a solid day with a mattock and spade I remove the last roots as dark falls, then retire into the house for refreshment. Sitting, drink in hand, by the window, I am not far from the hole that was a pampas plant. Suddenly a slight movement catches my attention. Something snuffles through the newly dug earth. It is about as long as my boot, and has noticable pale stripes down its grey/brown body. It moves cautiously and quickly to enjoy the feast that has just been laid on for it. I don't know which of us is happier.

I gradually discover that in my local area bandicoots are almost plentiful. Scottish gorse, another introduced and rampant weed, gives bandicoots improvised cover from the cats and dogs that are their most dangerous enemies. But in my yard they seem to have taken up residence in a large clump of New Zealand mint, with only faint tunnels and occasional scats to give away their presence.

More formal bandicoot studies in Tasmania have shown that they have a surprisingly varied diet. Most commonly they feed on the invertebrates they dig from the soil, including corbies, earthworms, crickets, beetles, slaters and spiders. But at times they'll feed on whatever else is available, including fungi and fruit.

In my yard they seem to get plenty of everything. Beneath the brief layer of green that passes for lawn, there are rich pickings. The introduced lumbricid earthworms that tend to dominate pasture and lawns can breed at an amazing rate. Where conditions are right, such as with an increased input of water and nitrogenous matter, worms can reach population densities of nearly 1,000 per square metre - making grass and lawn a bandicoot heaven.

But we are not the only ones to make lawns. In parts of the state, native animals not only benefit from lawns; they actually create their own. Two of our national parks, Mount William and Asbestos Range National Parks, were once grazing properties. When introduced grazing stock was first excluded from these parks, it was expected the pasture would revert to bush and forest cover. Though this happened to some extent, large parts of the parks have remained free of shrubs, giving the appearence of closely cropped lawns. In effect that is what thay are - marsupial lawns. Even in the wilder parts of the state, wallabies, wombats and other native animals favour grass over bush, creating clear grassed areas by and for their own grazing.

All of this may help us to imagine that grass has always been here. Yet geologically speaking it is a relative newcomer. Only during the last 10 - 15 million years has grass been at all common in Australia. Before that rainforest tended to dominate the vegetation of our once wet continent. It is only as the continent dried out that grass became widespread, which is a nice irony when we consider how much water we pour annually onto the (imported) grasses that make up our compulsorily green lawns.

Even those marsupials that don't directly eat grass may end up depending on it. So it is with the mountain pygmy possum (Burramys parvus). These tiny marsupials travel long distances to feast on bogong moths in the Snowy Mountains.

The larval stage of the bogong moth (Agrotis infusa) is the cutworm whose love of grass causes major pasture and crop damage over inland Australia. Once fattened up on grass, the larvae metamorphose. Then each summer the moths migrate to the Snowy Mountains, where they congregate in large numbers in crevices and rock shelters. They rest together (aestivate), overlapping one another in a single layer of up to several thousand individuals. While in the mountains they neither feed nor breed, but through this summer at rest they avoid the sparsely grassed and inhospitably hot inland.

Historically bogongs were also a target for Aboriginal groups, who cooked and ate vast numbers of them in annual highland feasts. The fat content of moth abdomens is supposed to be remarkably high, so it could be said that both humans and burramys lived off the fat of the land. And all thanks to the humble grass we tread underfoot.
Post a Comment