You may remember the article below which ran some months back on Fatbirder.com. Things have got even worse with the chance of human lives being lost growing and the impact on wildlife relentless.
After the story is a paper by Tim Neale of Deakin University which is as shocking as the article. Also appended is Denise’s latest letter to her local paper.
She told tells me:
We had nine fires July 2nd on our little road alone, and more since all lit apparently by an arsonist. I witnessed one start up last week just a 100 metres or so from our place. It looked like a small atom bomb. I rang triple zero and next thing the place was crawling with fire trucks and water bombers and spotter helicopters were buzzing us. It was like an ‘air show’ according to a neighbour. But it wasn’t fun, and our fire chief, mother of two young kids, got trapped in the flames and nearly died.
Now there’s a blaze south of Darwin that’s been going for three months and has burnt out 11 000 kms. There was no publicity until our ABC ran a story last night.
I have friends in the cattle industry who were promoting and spreading the stuff. As I witness the death of our fauna and flora en masse I’m wondering if I can ever spend time with them again.
THE GAMBA GRASS NIGHTMARE
Denise Lawungkurr Goodfellow
Introduced as food for cattle, gamba grass burns in a way that threatens northern Australia’s ecosystems. AAP Image/©CRC for Weed Management
A pestilence is quietly but definitively creeping across the Top End of Australia, destroying the tropical woodlands that have dominated this landscape for eons. That plague is a weed, Gamba Grass Andropogon gayana. It leaves in its wake, a panorama of tall exotic grass waving silently in the breeze, and little else. The trees and shrubs, the birds and other fauna, all have gone. Little else can exist in an infestation of gamba grass.
A perennial species native to the African savannah, gamba grass grows in clumps 4 m. high and a metre in diameter. Its stems can be as thick as bamboo. Gamba was introduced to Australia in the 1930s and embraced with gusto by the cattle industry. Graziers considered it a godsend for its ability to support many more cattle than native pasture (Csurhes 2005). By 1986, the Northern Territory Department of Primary Industries had produced an “easily established”, “highly productive”, and “drought resistant” cultivar that was “adapted to seasonally wet tropics”.
The first widespread trials of gamba grass were held in the late 1980s and 1990s in the Top End and in northern Queensland. Despite assurances that the plant could be safely contained within paddocks heavily grazed by stock it quickly escaped into surrounding savannah woodland (Petty, 2013). It is now known that gamba spreads easily “through pasture, bushland, riverine systems and transport corridors, and has diverse invasion pathways including via wind, water, animals and vehicles” (Beaumont, Keily & Kennedy, 2018). Often gamba-fuelled conflagrations are big enough for thermal updrafts to form pyrocumulus (literally fireclouds), their tops reaching several kilometres into the sky. These thermal air movements can carry gamba grass seed a long way (Clifton 2005b; Lamb, 2008). And each plant can produce between 15 000 to 244 000 seeds per plant annually.
Now gamba grass infests up to 1.5 million hectares of the Northern Territory, with smaller outbreaks scattered from Western Australia to Queensland. Each outbreak, even when consisting only of a few tussocks, can become a major infestation in less than five years. It is predicted that gamba grass could invade all woodland and open forest, and the edges of wetland and monsoon forest, representing an area of approximately 38 million ha (Douglas and Setterfield: 2005; Petty, Setterfield, Ferdinands, and Barrow: 2012; NT Government 2018). Tragically, the ranges of much of our most iconic avifauna, for example, Gouldian Finch and Hooded Parrot, lie totally within the potential reach of this weed.
Gamba is a ‘transformer’ weed, that is, it “transforms” the natural environment from forest to monotypic grassland. It does this by crowding out native flora; by changing nutrient and water cycles; and by burning many times hotter than a typical Top End grass fire. Gamba-fuelled fires are spectacular. They have the fast-moving front typical of a grassfire (Williams & Cook, 2018), but with flames reaching tens of metres into the canopy.
Our eucalypt-dominated woodlands cannot withstand blazes fuelled by gamba grass. While most are protected from the cool fires common to this habitat by thick or reflective bark, gamba-fuelled fires will kill them. Sixty percent of trees burnt in a gamba-fuelled fire near our property a year ago are dead.
As the trees disappear so will much of the native fauna. Tree hollows, for example, are essential for 17% of Australian bird species, over 42% of mammals and nearly 30% of reptiles (Gibbons and Lindenmayer 1997). In the Top End avifauna utilising nest hollows include several species of duck including Green Pygmy-goose and Radjah Shelduck, cockatoos and parrots, including Hooded Parrot, owls and allies, kingfishers, Dollarbird, Black-tailed Treecreeper, woodswallows, and Gouldian Finch. The latter species nest in the hollow branches of a limited number of eucalypts, including Salmon Gum, E. tintinnans. It takes up to eighty years or longer for suitably-sized tree hollows to form.
Even if there is no fire much fauna will suffer, and granivores are at a particular disadvantage. For example, Gouldian Finch and Partridge Pigeon feed largely on the seeds of native grasses, and both breed in the early Dry Season when grass seed is plentiful. When seed has fallen to the ground cool fires cleared the curing grasses from the ground allowing the birds to continue feeding; when carrying out surveys of Gouldian Finch in the late 1980s I looked for the bird on recently burnt ground.
Gamba grass crowds out the species of grass on which the birds feed. Furthermore, it burns so hot that any seed that does fall to the ground is destroyed. And the next year there is another crop of gamba, ready to spring into action leading to an indefinite cycle of hot, late fires that kill trees and other plants leading to further gamba grass invasion – the grass-fire cycle, and thus creating what one writer has called the “field of nightmares” (Aaron Petty,(http://theconversation.com/field-of-nightmares-gamba-grass-in-the-top-end-12178; 2013).
This “triffid of the plant world” (Tim Low of the Invasive Species Council https://invasives.org.au/project/gamba-grass/. Accessed 5 Sep, 2017) is a weed of national significance, and landholders are expected to control it on their properties. However, the importance of gamba to the cattle industry has meant that various stations have been allowed to keep grazing cattle on the weed (Lawler, 2018) to the dismay of indigenous rangers who find themselves fighting a losing battle trying to control the weed and fight fires (Fitzgerald & Burton, 2018), and those of us who care about our wildlife.
New infestations keep appearing and it is very doubtful that governments will expend the millions of dollars needed to both control the weed and fight fires. Such blazes are often uncontrollable anyway. One firefighter faced with a local firestorm remarked that if they couldn’t hold it “we’re screwed”. That comment could apply to a large number of birds and other fauna, as well as flora, across a huge swathe of the Australian continent. The genie is out of the bottle.
Here’s Denise’s letters~:
Recently, Prime Minister Scott Morrison has announced a plan to plant 1 billion trees in a move expected to remove 18 million tons of greenhouse gases from the environment each year between now and 2030.
Yet, will the Federal Government’s plan balance the increase in emissions caused by by Gamba-fuelled fire?
Gamba grass now infests about 1.5 million hectares in the Top End and has the potential to invade at least 38 million hectares. This four metre high tussock grass burns far hotter than the fires our vegetation has evolved to cope with, and most plants, including trees die.
In a 2008 declaration to government, 200 scientists predicted that repeated Gamba-fuelled fires would result in monocultures of this weed as native vegetation is killed. In 2019 this prediction is coming true. Fields of waving exotic grass are replacing much of our woodland and forest.
The density of trees per ha of Top End woodland varies greatly, and so it’s anyone’s guess how many trees are being lost. In a 2010 paper weed scientists Brooks, Setterfield and Douglas counted 140 dead trees per hectare at a study site at Adelaide River, killed by Gamba grass fire in just six years (unpublished information, Bushfires NT). Properties near us have lost half their mature trees because of Gamba-fuelled fires in the last few years alone.
Now, there’s a megafire in the Daly River region, affecting over 11,000km2. It has apparently been burning for three months (https://twitter.com/RohanFisher4/status/). So how many trees might be lost in this one fire? 100 million is a conservative guess. Then there are the hundreds of smaller fires each year, every year.
I suspect that the PM is going to need to raise the number of trees he wants to plant in order to reduce Australia’s greenhouse emissions.
Here’s a PDF of the scientific paper entitled: