*[Enwl-eng] UN unveils plan to stop invasive species disaster
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No images? Click here  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 Was this email forwarded to you? Join the 20,000 people who get one email every week about the most important issue of our time. Subscribe to 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.  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.  While some invasive animals have breached Antarctica, the continent is still pristine. Our challenge is keeping it that way.  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.  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?  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. Latest from The Conversation on climate change
From: Imagine newsletter
Sent: Wednesday, September 06, 2023 10:02 PM
Subject: UN unveils plan to stop invasive species
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