Invasive species are one of the biggest threats to biodiversity worldwide and one of Australia’s worst environmental problems. So it’s not a big surprise to learn invasive animals and weeds may also affect carbon emissions.
Evidence is emerging to show when we manage invasive species there can be co-benefits for the climate. Here’s four areas where eradication, control and management of invasive species could help to keep our precious carbon stores in good shape so they can continue to play their crucial function in a healthy environment.
Feral pigs erode the soil, releasing carbon dioxide
Feral animals can contribute to climate change by eroding and destroying carbon sinks such as soil, wetlands and peatlands. Take feral pigs which are like “mini tractors”, uprooting the soil as they search for food, releasing the carbon stored within.
Researchers at the University of Queensland recently looked into the impact of feral pigs on climate change globally and found they produce as much carbon dioxide as 1.1 million cars every year. Those emissions aren’t shared equally around the world either – in fact, due to our large populations of feral pigs, Australia and New Zealand account for 60% of those emissions. The report’s lead author, Dr Christopher O’Bryan, says it’s a conservative estimate and emissions could be three or four times higher.
Feral horses are ravaging peatlands, our ancient carbon stores
Peatlands — such as the sphagnum bogs of our alpine and sub-alpine regions — are nature’s secret weapon when it comes to tackling climate change. Globally, they store over a third of the planet’s soil carbon. That’s more than in all the world’s forests. Put another way: 5% of the world’s carbon emissions is due to damage to peat moss.
In Australia’s alpine regions, feral horses, deer and pigs are ravaging Australia’s precious peatlands, turning them from a safeguard against climate change into a driver of emissions.
What’s worse is peatlands take thousands of years to recover. A study on the impacts of feral horses in the Australian alps shows peat soils build up about 1 metre every 3,000 years. This means vital carbon stores in Australia’s alps damaged by feral horses over just a few decades, will take thousands of years to fully recover.
Invasive weeds like gamba grass can increase the risk and intensity of bushfires, increasing carbon emissions
Gamba grass is one of Australia’s most alarming invasive species, fuelling hotter, more dangerous fires that threaten homes and livelihoods. This weed can transform savanna habitats into monocultures. It is a highly invasive species that is native to Africa but has become established in parts of Australia, including the Northern Territory.
“Gamba grass is the worst of the worst when it comes to invasive weeds in Northern Australia. It can grow up to four metres high and fuels hotter, more intense fires which are transforming the Top End by reducing tree cover, changing water availability, depleting nutrients and increasing greenhouse gas emissions,” says Andrew Cox, CEO of the Invasive Species Council.
Feral buffalo produce high amounts of methane
Researchers from Charles Darwin University have been evaluating culling feral buffalo for carbon credits. With one adult buffalo emitting the equivalent of more than two tonnes of carbon dioxide per year, that’s a possible two carbon credits per buffalo. This approach could bring benefits to both landowners and the environment, helping to fund invasive species management. The report earmarks the future potential for other invasive species, saying: “While we estimated the direct enteric emissions from only one species in northern Australia, the same approach could be applied to other species across Australia, including cattle, camels, goats, and deer.”
Nature’s complexity means we are continually learning more about the intricate web of systems that sustain life on Earth. While further research is needed to better understand the intersection between invasive species management and climate change mitigation, it’s an exciting space that could deliver a double-dividend for nature and climate.
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