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Home / Science / BBC – Future – How weeds fight climate change

BBC – Future – How weeds fight climate change



More than 60 years ago, when he was a child, farmer Peter Andrews saw his first dust storm. He still remembers it. "The noise was terrible," he says. "We hid in the house and waited for it to pass by. The whole sky was dark. And the damage we saw the next day was even worse. "

The wind had ripped many trees on his family's estate completely naked. Some of their horses and cattle suffocated and could not breathe the dust.

This early experience has led him to a special calling: He tried to regenerate Australia's land because dust storms occur in hot, arid regions where there is little vegetation anchoring the soil.

"It really got me thinking … how to find solutions to keep the country in balance," says Andrews. "For many decades, I've learned by observation how to keep the land fruitful, how every landscape has its own natural system. Here in Australia we have devastated the landscape with European agriculture. We have to find a way to regenerate the land. "

In the 1

970s and 1980s, Andrews was interested in sustainable agriculture. He looked at the waterways and the plants that grew on his property and tried to avoid fertilizer and weed killers. He wanted to make the yard as weatherproof as possible.

One major problem was the drought. Another was that weeds could grow on the property while native plants were not.

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He had two major findings. First, plants are essential to keep the land in balance. Second, it's the water.

Every landscape, he saw, has its own contours-a point where the water runs out and a point where it flows. To regenerate an eroding landscape, start at the highest point, slow down the water flow, then work down and filter the water with the existing vegetation, he explains. This was the genesis of his idea of ​​natural sequence agriculture.

Weeds for Water

Climate change and land clearing have led to extreme temperatures and extreme weather events in Australia

It was the driest and hottest year recorded for most of Australia. A recent scientific report describes how Australia's past summer was marked by "continual heat waves and hot days, bushfires all over Australia, and heavy rains and floods in northern Queensland." According to the report, climate change and deforestation have resulted in extreme temperatures and extreme weather events. "For the past four years, it has been the four hottest years in which global surface temperature has been measured." Many people who can neither grow nor feed cattle or sheep leave their farms.

Investigations by the Australian Nature Conservation Council (NCC) also warn against deforestation in Australia, especially in New South Wales I have not seen for more than 20 years, "says NCC General Manager Kate Smolski.

The NNC Report states that forests are being cut down, that there are fewer trees to "rain, cool the weather and store carbon."

These intense and worsening weather conditions, conditions and deforestation, Andrews Australia calls it Australia "the laboratory for the world when it comes to adapting to the weather." Second, increase groundwater, third, restore the vegetation, possibly with weeds, fourth, understand the specific needs of a particular landscape

Andrews & # 39; ideas are not universally accepted ades he was seen by many as an outsider.He is not a scientist un It took until 2013 for scientific evidence to show that natural sequencing can be effective.

Some critics wonder if better land management and avoidance of destructive farming methods (such as cutting down trees) would require natural sequencing in the first place. Others disagree with its suggestion to use weeds: Conservation projects usually encourage the planting of endemic Australian plants, rather than allowing invasive weeds to grow, as they are believed to compete with native plants for scarce water.

But a pilot site for natural sequencing is an hour's drive east of Canberra, and seems to prove that Andrews' ideas about weeds can work, albeit on a small scale. The pilot site is a 6 km section of Mulloon Creek, which is run by a network of organic farms that now use and promote the work of Andrews.

The United Nations Sustainable Development Solutions Network announced in 2016 that Mulloon Creek Natural Farms is one of the world's few agricultural sites that are truly sustainable

The United Nations Sustainable Development Solutions Network has In 2016, the Mulloon Creek Natural Farms announced that they are one of the few agricultural sites in the world that are truly sustainable, and praised the Model of Natural Sequence Farming.

In Mulloon Creek, I meet Gary Nairn, chair of the Mulloon Institute, a research and teaching organization on renewable sustainable agriculture that promotes Andrews' work. He points to the invasive blackberries that his team has cut down; The picked and shredded shrubs now clog a part of a pond and help filter it. The sound of running water and small birds fills the air as I approach.

The Mulloon Institute, located in a barn next to a pond named after Andrews, educates farmers, scientists and scientists with natural sequence methods students. The Mulloon Institute also works with several Australian universities to monitor the water along the stream, using piezometers (water meters) installed by scientists from Australia National University and the University of Canberra.

"Scientists have shown this natural sequence agriculture increases water flow and raises water levels," explains Nairn.

His team is now working on a further 43km of creek running through 20,000 hectares of farmland to build more weed-like, leaky weirs such as a dam wall across the creek. The weirs are made of stones; The cracks between the stones are filled with chopped blackberry weeds to filter and slow the flow.

Despite this little rain, the stream now runs again and pastures, which used to be dry soil and had dried off the drought, turn green. This is because the weirs work and the soil can absorb more moisture, allowing the plants to grow on the banks.

"The weeds and weirs take the energy out of the water and spray the landscape," says Nairn.

The whole process is a bit like creating "huge sponges with weeds," he says.

What we have learned is never to pull a weed until you know what the purpose of this weed is – Gary Nairn

"We have learned never to pull weeds until you know what the purpose of this weed is , Many weeds usually mean that something is wrong with the fertility of the land. If you pull it out, you have to replace it with another plant, "he says.

But these weeds can be crushed and placed in a stream, as at the pond in front of the Mulloon Institute.

According to Nairn, native Australian plants are slowly replenishing. Some already do this along the stream.

Carbon sink

The beauty of weeds is that they also act like a carbon sink: a system that unloads carbon from the atmosphere and expresses it in another form of storage. This can help bring climate change under control.

"Forests, oceans and soils can all remove and store carbon dioxide from the atmosphere," says Christa Anderson, a climate researcher for the World Wide Fund for Nature in the United States. [19659002] Anderson explains that the amount of carbon dioxide a particular ecosystem can absorb depends on where it is and how it is managed.

There are a variety of agricultural practices that can also increase carbon storage – Christa Anderson

Forests have the greatest potential for additional carbon storage and can therefore help reduce emissions of carbon dioxide and other greenhouse gases. There are also a variety of agricultural practices that can increase carbon storage, "says Anderson.

"We need to remove carbon from the atmosphere by improving forest management, protecting and restoring wetlands, bogs, and seagrasses, and improving our agriculture."

Some scientists are now wondering if even small projects like the one in Mulloon Creek could serve as a carbon sink for habitat restoration if enough family members also form "giant weed sponges".

"Keeping water in the landscape also puts carbon into the landscape, making it more productive and sustainable," Adds Nairn.

This is important because so much forest is cleared for massive agriculture that carbon sinks are lost. Parts of northern New South Wales and Queensland were made by land clearing for massive farms. Gigatonne for gigatonne, however, leaves soils and plants twice as much carbon as the atmosphere – so more plants, and not less, are needed to absorb our increasing fossil-fuel carbon production.

The question is whether smaller projects such as these will be enough to bring the farms back to life in the face of massive rates of deforestation and land degradation.

Nairn believes that there is reason for optimism. "You just need the will to do it," he says. "What we are proud of is that we give hope to young people with the natural sequence-growing hope – hope you can still live in the countryside if you better manage water and plants."

Peter Andrews agrees although he always adds I did not like the term "Natural Sequence Farming".

"The name annoys me. It's really just watching the landscape and returning to what it used to be as good as it gets. Every facility has a purpose.

While world leaders are debating whether and when to reduce CO2 emissions, a sustainable farm in Mulloon Creek, Australia demonstrates that low-tech weeds can help lower carbon and bring the river back to the river bring to . It is a small but significant solution to a serious global problem.

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