*[Enwl-eng] UN unveils plan to stop invasive species disaster
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Thu Sep 7 20:06:41 MSK 2023
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If you've encountered Japanese knotweed in your garden, or heard about
the Asian hornets threatening bees around the world, you'll know invasive
alien species can be disastrous for ecosystems.
At least 3,500 invasive alien species are threatening the diversity of
living things on Earth and costing the global economy US$423 billion (£363
billion) a year. That's according to the most thorough investigation to date
by a global body of experts tasked by the UN with assessing the state of
nature and its benefits to society.
Humankind is moving plants, animals and other organisms around the
world at an alarming rate. As these non-natives bed down in new
environments, they can proliferate unbound by predators or other pressures
which have kept locally evolved species in check – and ultimately outcompete
them for habitat and food.
After a summer of extreme weather in the northern hemisphere has
highlighted the threat of climate change to Earth's ecosystems, this new
report suggests how wide-ranging the assault on our planet's life support
systems is.
You're reading the Imagine newsletter – a weekly synthesis of academic
insight on solutions to climate change, brought to you by The Conversation.
I'm Jack Marley, energy and environment editor. This week, discussing how
climate change and biological invasions are changing life on Earth.
Climate change appears to have aided the spread of non-native species
in some studied ecosystems. Marine heat waves, bouts of abnormally high sea
temperatures, have decimated hard coral populations in the Mediterranean,
for example. The loss of these intricate, habitat-forming species will deny
shelter to countless other natives they have evolved alongside.
In their place, exotic species capable of withstanding higher
temperatures such as lionfish and silver-cheeked toadfish are gaining a
foothold.
"Some research even suggests that invasive species in the eastern
Mediterranean, where native populations have collapsed, will soon become the
only ones capable of sustaining ecosystems," says John Spicer, a professor
of marine zoology at the University of Plymouth.
Combined, invasive species and climate change can accelerate the
deterioration of biodiversity, the name scientists give to the dazzling
variety of life found on Earth. As unique ecosystems containing species
which may have evolved over millennia in relative isolation, including
Antarctica, become more uniform, they could also become more vulnerable to
the effects of climate change.
"Already established invasive alien species can supercharge
environmental disasters," say Andy Sheppard (CSIRO), Melodie McGeoch (La
Trobe University), Philip Hulme (Lincoln University, New Zealand) and Phill
Cassey (University of Adelaide).
"For example, the wildfire-promoting properties of introduced African
pasture grasses exacerbated bushfires in Hawaii this year."
In some cases, the dynamic flows in the opposite direction. Scientists
fear that some invasive species are accelerating the rate at which Earth is
heating.
Kudzu is a vine related to beans and other legumes. After evolving in
east Asia, kudzu was transplanted to the US via a handful of plants in 1876,
where it now occupies millions of hectares. Kudzu can grow up to a metre
every three days, allowing it to quickly engulf native needled pine forests
and grasslands, not to mention buildings and electricity transmission lines.
Among the most nefarious of kudzu's talents is its ability to speed up
the rate at which soil microbes in the forests it invades break down
decomposing plant matter.
"When it takes over ecosystems, this invader causes soils to surrender
their carbon and release it as greenhouse gas," says Malcolm Campbell, a
professor of plant biology at the University of Toronto.
Invaders must die?
Not all invasive plants cause the soil to "puke carbon" as Campbell
describes it. Knotweed, native to Japan, China and Korea, may have actually
helped soil store more carbon in some of the European and North American
habitats it has overran according to the same study, by plant ecologists
Nishanth Tharayil and Mioko Tamura of Clemson University.
Cold comfort for anyone who lives near rivers choked with knotweed.
Nevertheless, it demonstrates that the contributions of alien species to the
ecosystems and communities they find themselves in are not entirely
negative. Even the designations "invasive" and "alien" are complicated and
subjective to an extent.
"Alien species can also benefit people, says Kelvin Peh, an associate
professor of conservation science at the University of Southampton.
"Perceptions of their threat can vary depending on who you ask, which can
complicate their management".
Peh notes that on the Caribbean island of Montserrat, introduced
cattle, sheep, goats and pigs have gone feral, but regular culls offer a
steady supply of meat for local cuisines.
Elsewhere, humanity's proclivity for moving species around could help
some ecosystems to adapt to climate change according to a team of
researchers from the University of Debrecen in Hungary. Judit Sonkoly, a
research fellow in ecology, came to this conclusion after allowing stowaway
seeds in samples of commercial potting mix to germinate in a greenhouse, and
discovering an average of six species per litre of soil.
Five of these species were not native to Hungary. Some seeds had
travelled more than 1,000 kilometres from the peat they originated in to the
garden centre they were sold in.
"Many of their former habitats are becoming too hot or dry, so moving
can ensure plants persist in rapidly changing landscapes," Sonkoly says.
"The loss of large wild herbivores, herded livestock and fruit-eating
wildlife has already severed options for long-distance dispersal. In their
absence, humanity can act as the main dispersal agent, transporting many
species over very long distances."
It would be a mistake to write off invasive species as a law unto
themselves, argues Peh. "Like other environmental changes, biological
invasions are largely determined by how people live and how society is
organised," he says.
This notion leaps out at you when you compare the composition of
modern plant communities in distant regions.
"We investigated the alien flora of four European empires (British,
Spanish, Portuguese and Dutch) and showed that regions that were once
occupied by the same European colonial power are still more similar today
compared to other regions not occupied by the same power," say Bernd Lenzner
and Guillaume Latombe, experts in environmental change at Universität Wien
and the University of Edinburgh respectively.
"The longer regions were occupied by a colonial power, the more
similar they are to each other."
Today's invasive species problem was centuries in the making. But
after modelling future scenarios for biodiversity according to how well
countries cooperate to regulate trade, the biggest driver of biological
invasions, Latombe concluded that there is still time to bring the rate of
new invasions under control.
"[Either] countries eschew cooperation but maintain lightly regulated
trade and preside over a rising number of invasions [or] high levels of
regulation and regional and global governance foster low or stable levels of
biological invasions," he says.
"While invasions have already caused substantial damage, the future
outcome is still largely ours to decide".
- Jack Marley, Environment commissioning editor
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Imagine.
Invasive species risk a biodiversity disaster – but there is still
time to stop it
Modern ecosystems are very different to how they were just a few
centuries ago.
Read more
The true damage of invasive alien species was just revealed in a
landmark report. Here’s how we must act
Alien invaders are penetrating the borders of every country in the
world. Now the full extent of the problems and potential solutions have been
exposed, in a new United Nations report.
Read more
Invasive species are threatening Antarctica’s fragile ecosystems as
human activity grows and the world warms
While some invasive animals have breached Antarctica, the continent is
still pristine. Our challenge is keeping it that way.
Read more
The ‘plant that ate the South’ makes soil puke carbon
Recent research shows that the impact of invasive species kudzu is
more troublesome than had been previously thought.
Read more
Growing plant trade may spread invasive species – but help ecosystems
adapt to climate change
Potting soils are helping plant seeds travel. Is it benign or harmful?
Read more
European colonialism has had a lasting legacy on how plants are
distributed around the world
Scientists have found more 'alien species' today in regions that were
once key parts of European empires.
Read more
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Sent: Wednesday, September 06, 2023 10:02 PM
Subject: UN unveils plan to stop invasive species disaster
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