Tag Archives: Species loss

As big forests shrink, the carbon leaks and the heat rises

The world’s greatest forests are turning to patchwork. The patches get more frequent, the carbon leaks and the heat rises.

LONDON, 16 September, 2021 − The world’s tropical forests are getting smaller, and this process may be inexorable. That is because, in effect, the great rainforest canopies are being shredded into ever-smaller pieces. As this happens the carbon leaks, the heat rises.

In other words every year, a greater proportion of natural intact forest becomes a forest edge. And researchers have demonstrated, repeatedly, that canopy up to 100 metres from the edge of any forest becomes less effective at storing carbon, maintaining moisture and conserving biodiversity.

At the beginning of this century, researchers report in the journal Science Advances, they pored over high-resolution forest cover maps of the globe to count 131 million fragments of forest: that is forest subdivided by roads, or mining and quarrying works, or plantations, or clearance for logging, or for plantations or ranches. In just 10 years, this number had reached 152 million.

In Africa alone, the number of forest fragments increased from 45 million to 64 million: that is an increase of 42%. In the year 2000, the area of forest edge − the irrevocably degraded area − for the entire tropics had reached 27%. Ten years later, this proportion was 31%.

Increasing forest loss

“This situation has deteriorated so much that now almost one-third of the world’s tropical forest areas are in edge areas. If deforestation is not stopped, this trend will continue,” said Rico Fischer of UFZ, the Helmholtz Centre for Environmental Research in Leipzig, Germany, who led the study.

“The edge, unlike the forest interior, is subject to direct sunlight. It is more exposed to the wind. Humidity also decreases in the edge areas. The altered microclimate particularly damages the large trees that depend on a good water supply.”

Forest conservation is a key component in the global efforts to limit climate change and slow global temperature rise. Across the entire tropics, the study found, the average size of these forest fragments had fallen, from 15 hectares in 2000 to 12 hectares in 2010. In those years, an area of 177 million hectares that had once been undisturbed, intact forest has been lost either through direct deforestation, or conversion to forest edge.

This is an area almost the size of Indonesia. By the century’s end, half of all tropical forest will be classified as forest edge. The loss of forest actively delivers extra carbon into the atmosphere to accelerate global heating even more alarmingly, and that could mean even more forest loss, as cycles of drought and fire become more probable in a warming world.

“Almost one-third of the world’s tropical forest areas are in edge areas. If deforestation is not stopped, this trend will continue”

The problem, of course, is the road: without new roads, miners, farmers, ranchers and loggers could not have made much impact on what were once vast intact forests in tropical Africa, the Amazon basin and south-east Asia.

And the problem will continue: within the next 30 years, there could be another 25 million kilometres of new road, enough to circle the globe 600 times, and most of these in the developing world, that is, the tropics.

Where these roads divide the forest they precipitate carbon loss: at the beginning of this century, forest edges surrendered around 420 million tonnes of carbon a year to the atmosphere. By 2010, this had gone up to 450 million.

Every year now in the tropics, the clearance, destruction or degradation of forest releases between 1,000 and 1,500 million tonnes of carbon. The loss of efficiency at the edge of the surviving forest could increase this figure by almost a third.

Halt to deforestation

And, of course, the gaps between surviving patches of tropical forest are getting bigger. This is good for neither the trees nor the creatures that live under the forest’s protection.

“This makes the long-term survival of animal species such as the jaguar, which depends on large, connected forest areas, more difficult,” said Franziska Taubert, a co-author, also at the UFZ Leipzig centre.

The scientists calculate that at the present rate of deforestation, half of all tropical forest by the end of this century will be classed as forest edge, and this forest edge will release 530 million tonnes of carbon into the atmosphere every year. If the rate of tropical deforestation is cut by half that proportion will still increase to 40%. If all deforestation is stopped by 2050, the proportion could be held to 30%.

“Only if deforestation of the rainforest is stopped from 2050 onwards can emissions be limited to a maximum of 480 million tonnes of carbon,” said Dr Fischer. − Climate News Network

The world’s greatest forests are turning to patchwork. The patches get more frequent, the carbon leaks and the heat rises.

LONDON, 16 September, 2021 − The world’s tropical forests are getting smaller, and this process may be inexorable. That is because, in effect, the great rainforest canopies are being shredded into ever-smaller pieces. As this happens the carbon leaks, the heat rises.

In other words every year, a greater proportion of natural intact forest becomes a forest edge. And researchers have demonstrated, repeatedly, that canopy up to 100 metres from the edge of any forest becomes less effective at storing carbon, maintaining moisture and conserving biodiversity.

At the beginning of this century, researchers report in the journal Science Advances, they pored over high-resolution forest cover maps of the globe to count 131 million fragments of forest: that is forest subdivided by roads, or mining and quarrying works, or plantations, or clearance for logging, or for plantations or ranches. In just 10 years, this number had reached 152 million.

In Africa alone, the number of forest fragments increased from 45 million to 64 million: that is an increase of 42%. In the year 2000, the area of forest edge − the irrevocably degraded area − for the entire tropics had reached 27%. Ten years later, this proportion was 31%.

Increasing forest loss

“This situation has deteriorated so much that now almost one-third of the world’s tropical forest areas are in edge areas. If deforestation is not stopped, this trend will continue,” said Rico Fischer of UFZ, the Helmholtz Centre for Environmental Research in Leipzig, Germany, who led the study.

“The edge, unlike the forest interior, is subject to direct sunlight. It is more exposed to the wind. Humidity also decreases in the edge areas. The altered microclimate particularly damages the large trees that depend on a good water supply.”

Forest conservation is a key component in the global efforts to limit climate change and slow global temperature rise. Across the entire tropics, the study found, the average size of these forest fragments had fallen, from 15 hectares in 2000 to 12 hectares in 2010. In those years, an area of 177 million hectares that had once been undisturbed, intact forest has been lost either through direct deforestation, or conversion to forest edge.

This is an area almost the size of Indonesia. By the century’s end, half of all tropical forest will be classified as forest edge. The loss of forest actively delivers extra carbon into the atmosphere to accelerate global heating even more alarmingly, and that could mean even more forest loss, as cycles of drought and fire become more probable in a warming world.

“Almost one-third of the world’s tropical forest areas are in edge areas. If deforestation is not stopped, this trend will continue”

The problem, of course, is the road: without new roads, miners, farmers, ranchers and loggers could not have made much impact on what were once vast intact forests in tropical Africa, the Amazon basin and south-east Asia.

And the problem will continue: within the next 30 years, there could be another 25 million kilometres of new road, enough to circle the globe 600 times, and most of these in the developing world, that is, the tropics.

Where these roads divide the forest they precipitate carbon loss: at the beginning of this century, forest edges surrendered around 420 million tonnes of carbon a year to the atmosphere. By 2010, this had gone up to 450 million.

Every year now in the tropics, the clearance, destruction or degradation of forest releases between 1,000 and 1,500 million tonnes of carbon. The loss of efficiency at the edge of the surviving forest could increase this figure by almost a third.

Halt to deforestation

And, of course, the gaps between surviving patches of tropical forest are getting bigger. This is good for neither the trees nor the creatures that live under the forest’s protection.

“This makes the long-term survival of animal species such as the jaguar, which depends on large, connected forest areas, more difficult,” said Franziska Taubert, a co-author, also at the UFZ Leipzig centre.

The scientists calculate that at the present rate of deforestation, half of all tropical forest by the end of this century will be classed as forest edge, and this forest edge will release 530 million tonnes of carbon into the atmosphere every year. If the rate of tropical deforestation is cut by half that proportion will still increase to 40%. If all deforestation is stopped by 2050, the proportion could be held to 30%.

“Only if deforestation of the rainforest is stopped from 2050 onwards can emissions be limited to a maximum of 480 million tonnes of carbon,” said Dr Fischer. − Climate News Network

Waste plastic deluge could soon prove irreversible

The waste plastic deluge fouling the world’s beaches could be more than just an eyesore. It could be a toxic timebomb.

LONDON, 8 July, 2021 − European researchers have warned that the wave of pollution engulfing the globe could be nearing a tipping point. The waste plastic deluge could become an irreversible crisis.

Somewhere between 9 and 23 million tonnes of polymers get into the rivers, lakes and seas of the world every year. Even more may be getting into the terrestrial soils and by 2025 − unless the world changes its ways − these levels of pollution will have doubled.

And, the researchers warn, the uncertain and as yet unknown effects of weathering on such volumes of plastic could bring what has been called “a global toxicity debt” as drinking bottles, bits of fishing gear, coffee cups and carrier bags become covered with microbial life; as plastic particles foul the sea’s surface, become suspended in the water column, and build up in the sediments of the ocean.

Plastic waste has now been found everywhere: on the world’s highest mountains, in the deepest oceanic trenches, on the beaches of desolate islands in the Southern Ocean, in the Arctic ice, and in the tissues of living creatures, from seabirds to whales.

Worsening climate crisis

“Right now we are loading up the environment with increasing amounts of poorly reversible plastic pollution. So far we don’t see widespread evidence of bad consequences but if weathering plastic triggers a really bad effect we are not likely to be able to reverse it,” said Matthew Macleod of Stockholm University in Sweden.

“The cost of ignoring the accumulation of persistent plastic pollution in the environment could be enormous. The rational thing to do is act as quickly as we can to reduce emissions of plastic into the environment.”

Professor Macleod and colleagues warn in the journal Science that alongside threats to wildlife, and the potential hazard of environmental poisoning, there could be a number of other hypothetical consequences.

Plastic pollutants could exacerbate climate change by disrupting the traffic of carbon between the natural world and the atmosphere, and they could heighten biodiversity loss in the already over-fished oceans.

Researchers do not yet know of the long-term non-toxicological effects of plastic pollution on carbon and nutrient cycles, soil and sediment fertility, and biodiversity. Nor has there been any assessment of the potential for delayed toxic effects as the plastic polymers are altered by weathering.

“The rational thing to do is act as quickly as we can to reduce emissions of plastic into the environment”

And if there are such effects, then they could persist, to trigger what the scientists call a “tipping point”, long after people have stopped discarding plastic waste into the environment.

“The world promotes technological solutions for recycling and to remove plastic from the environment. As consumers, we believe that when we properly separate our plastic trash, all of it will magically be recycled,” said Mine Tekman, of the Alfred Wegener Institute in Germany, and a co-author.

“Technologically, recycling of plastic has many limitations, and countries that have good infrastructures have been exporting their plastic waste to countries with worse facilities. Reducing emissions requires drastic actions, like capping the production of virgin plastic to increase the value of recycled plastic, and banning the export of plastic waste unless it is to a country with better recycling.”

And her colleague Annika Jahnke of the Helmholtz Centre for Environmental Research in Germany warned: “In remote environments, plastic debris cannot be removed by cleanups, and weathering of large plastic items will inevitably result in the generation of large numbers of micro- and nano-plastic particles as well as leaching of chemicals that were intentionally added to the plastic and other chemicals that break off the plastic polymer backbone.

“So, plastic in the environment is a constantly moving target of increasing complexity and mobility. Where it accumulates and what effects it may cause are challenging or maybe even impossible to predict.” − Climate News Network

The waste plastic deluge fouling the world’s beaches could be more than just an eyesore. It could be a toxic timebomb.

LONDON, 8 July, 2021 − European researchers have warned that the wave of pollution engulfing the globe could be nearing a tipping point. The waste plastic deluge could become an irreversible crisis.

Somewhere between 9 and 23 million tonnes of polymers get into the rivers, lakes and seas of the world every year. Even more may be getting into the terrestrial soils and by 2025 − unless the world changes its ways − these levels of pollution will have doubled.

And, the researchers warn, the uncertain and as yet unknown effects of weathering on such volumes of plastic could bring what has been called “a global toxicity debt” as drinking bottles, bits of fishing gear, coffee cups and carrier bags become covered with microbial life; as plastic particles foul the sea’s surface, become suspended in the water column, and build up in the sediments of the ocean.

Plastic waste has now been found everywhere: on the world’s highest mountains, in the deepest oceanic trenches, on the beaches of desolate islands in the Southern Ocean, in the Arctic ice, and in the tissues of living creatures, from seabirds to whales.

Worsening climate crisis

“Right now we are loading up the environment with increasing amounts of poorly reversible plastic pollution. So far we don’t see widespread evidence of bad consequences but if weathering plastic triggers a really bad effect we are not likely to be able to reverse it,” said Matthew Macleod of Stockholm University in Sweden.

“The cost of ignoring the accumulation of persistent plastic pollution in the environment could be enormous. The rational thing to do is act as quickly as we can to reduce emissions of plastic into the environment.”

Professor Macleod and colleagues warn in the journal Science that alongside threats to wildlife, and the potential hazard of environmental poisoning, there could be a number of other hypothetical consequences.

Plastic pollutants could exacerbate climate change by disrupting the traffic of carbon between the natural world and the atmosphere, and they could heighten biodiversity loss in the already over-fished oceans.

Researchers do not yet know of the long-term non-toxicological effects of plastic pollution on carbon and nutrient cycles, soil and sediment fertility, and biodiversity. Nor has there been any assessment of the potential for delayed toxic effects as the plastic polymers are altered by weathering.

“The rational thing to do is act as quickly as we can to reduce emissions of plastic into the environment”

And if there are such effects, then they could persist, to trigger what the scientists call a “tipping point”, long after people have stopped discarding plastic waste into the environment.

“The world promotes technological solutions for recycling and to remove plastic from the environment. As consumers, we believe that when we properly separate our plastic trash, all of it will magically be recycled,” said Mine Tekman, of the Alfred Wegener Institute in Germany, and a co-author.

“Technologically, recycling of plastic has many limitations, and countries that have good infrastructures have been exporting their plastic waste to countries with worse facilities. Reducing emissions requires drastic actions, like capping the production of virgin plastic to increase the value of recycled plastic, and banning the export of plastic waste unless it is to a country with better recycling.”

And her colleague Annika Jahnke of the Helmholtz Centre for Environmental Research in Germany warned: “In remote environments, plastic debris cannot be removed by cleanups, and weathering of large plastic items will inevitably result in the generation of large numbers of micro- and nano-plastic particles as well as leaching of chemicals that were intentionally added to the plastic and other chemicals that break off the plastic polymer backbone.

“So, plastic in the environment is a constantly moving target of increasing complexity and mobility. Where it accumulates and what effects it may cause are challenging or maybe even impossible to predict.” − Climate News Network

Millions of species face extinction emergency

An extinction emergency unparalleled in the history of life on Earth could soon overtake millions of species – thanks to us.

LONDON, 8 June, 2020 – More than 500 terrestrial vertebrate species – birds, amphibians, mammals, reptiles – are on the brink of a worldwide extinction emergency. These are animal species with surviving populations of fewer than 1,000 individuals. They are to be found in tropical and subtropical regions and, significantly, they are concentrated in regions heavily affected by human activities.

Extinction is a natural part of the evolutionary process. But the number of simultaneously threatened species, and the link to direct human pressure, adds support for the argument that humanity is now witnessing the sixth, and possibly greatest, mass extinction in the history of life.

The same research has identified 388 vertebrate species with fewer than 5000 individuals in the surviving populations. Of these, more than four-fifths cling to survival in the same threatened regions, and may therefore also be heading for the brink of extinction.

Three distinguished scientists report in the Proceedings of the National Academy of Sciences that they analysed the International Union for the Conservation of Nature’s list of threatened species to identify 29,400 terrestrial vertebrates, 1.7% of which had fewer than 1,000 remaining individuals anywhere in the world.

There are many cases of local extinction: for a mix of reasons, birds or butterflies might disappear from places where they once were many, but continue to flourish in other zones. But too many local extinctions soon amount to global obliteration: the researchers identified 237,000 populations of vertebrates that had vanished since 1900.

Massive impact ahead

They see an ecological catastrophe in the making, and they urge governments and international agencies to act.

“What we do to deal with the current extinction crisis in the next two decades will define the fate of millions of species,” said study lead author Gerardo Ceballos, a senior researcher at the National Autonomous University of Mexico’s Institute of Ecology.

“We are facing our final opportunity to ensure that the many services nature provides us do not get irretrievably sabotaged.”

And his co-author Paul Ehrlich of Stanford University in California said: “When humanity exterminates populations and species of other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system.

“The conservation of endangered species should be elevated to a national and global emergency for governments and institutions, equal to climate disruption, to which it is linked.”

“It’s up to us to decide what kind of a world we want to leave to coming generations – a sustainable one, or a desolate one in which the civilisation we have built disintegrates rather than builds on past successes”

Nearly a fourth of all species on the planet could face extinction. In the course of the 11,000 years since the invention of agriculture human numbers have multiplied from about one million to 7.7 billion, and are rising fast. In the last 450 million years there have been at least five major extinctions, each destroying 70% to 90% of all life on Earth.

Although creatures alive on Earth today account for only 2% of all the creatures that have ever lived, the absolute number of species is greater now than ever before. “It is into such a biologically diverse world that we humans evolved, and such a world that we are destroying,” the authors write.

Extinction may be the greatest environmental problem, because it is irreversible. It is now happening at rates perhaps a thousand times faster than the “background rate” over the last tens of millions of years.

When a species disappears, it takes with it a unique set of biological riches, and – perhaps more dangerously – it creates a loss for other species that may in some way depend upon it. Extinction breeds extinction, the authors argue.

And as plants and animals vanish into oblivion, the biosphere’s capacity to recycle atmosphere, water and nutrients, to pollinate and fertilise, and to dispose of the dead and the waste, is diminished.

‘Ecological zombies’

Ecosystems that support and enrich all life also support and enrich humanity. At one stage 60 million bison maintained the prairie ecosystems of North America and in the course of doing so supported the then Native American population.

By 1884 only 325 individuals were left. The prairies are now largely farmland, and the 4000 surviving wild bison can be considered, the authors say, as “ecological zombies.”

Among other steps, they want to see a halt to the trade in wildlife – thought to be linked to the origins of the Covid-19 pandemic. All three have considerable reputations within science and they have all been making much the same argument for many years.

They calculate that in the last century 543 species of land vertebrate were extinguished. The same number could go in the next two decades. Human action created the problem: only human action can repair the damage.

“It’s up to us to decide what kind of a world we want to leave to coming generations – a sustainable one, or a desolate one in which the civilisation we have built disintegrates rather than builds on past successes,” said Peter Raven, president emeritus of the Missouri Botanical Garden, the third of the signatories. – Climate News Network

An extinction emergency unparalleled in the history of life on Earth could soon overtake millions of species – thanks to us.

LONDON, 8 June, 2020 – More than 500 terrestrial vertebrate species – birds, amphibians, mammals, reptiles – are on the brink of a worldwide extinction emergency. These are animal species with surviving populations of fewer than 1,000 individuals. They are to be found in tropical and subtropical regions and, significantly, they are concentrated in regions heavily affected by human activities.

Extinction is a natural part of the evolutionary process. But the number of simultaneously threatened species, and the link to direct human pressure, adds support for the argument that humanity is now witnessing the sixth, and possibly greatest, mass extinction in the history of life.

The same research has identified 388 vertebrate species with fewer than 5000 individuals in the surviving populations. Of these, more than four-fifths cling to survival in the same threatened regions, and may therefore also be heading for the brink of extinction.

Three distinguished scientists report in the Proceedings of the National Academy of Sciences that they analysed the International Union for the Conservation of Nature’s list of threatened species to identify 29,400 terrestrial vertebrates, 1.7% of which had fewer than 1,000 remaining individuals anywhere in the world.

There are many cases of local extinction: for a mix of reasons, birds or butterflies might disappear from places where they once were many, but continue to flourish in other zones. But too many local extinctions soon amount to global obliteration: the researchers identified 237,000 populations of vertebrates that had vanished since 1900.

Massive impact ahead

They see an ecological catastrophe in the making, and they urge governments and international agencies to act.

“What we do to deal with the current extinction crisis in the next two decades will define the fate of millions of species,” said study lead author Gerardo Ceballos, a senior researcher at the National Autonomous University of Mexico’s Institute of Ecology.

“We are facing our final opportunity to ensure that the many services nature provides us do not get irretrievably sabotaged.”

And his co-author Paul Ehrlich of Stanford University in California said: “When humanity exterminates populations and species of other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system.

“The conservation of endangered species should be elevated to a national and global emergency for governments and institutions, equal to climate disruption, to which it is linked.”

“It’s up to us to decide what kind of a world we want to leave to coming generations – a sustainable one, or a desolate one in which the civilisation we have built disintegrates rather than builds on past successes”

Nearly a fourth of all species on the planet could face extinction. In the course of the 11,000 years since the invention of agriculture human numbers have multiplied from about one million to 7.7 billion, and are rising fast. In the last 450 million years there have been at least five major extinctions, each destroying 70% to 90% of all life on Earth.

Although creatures alive on Earth today account for only 2% of all the creatures that have ever lived, the absolute number of species is greater now than ever before. “It is into such a biologically diverse world that we humans evolved, and such a world that we are destroying,” the authors write.

Extinction may be the greatest environmental problem, because it is irreversible. It is now happening at rates perhaps a thousand times faster than the “background rate” over the last tens of millions of years.

When a species disappears, it takes with it a unique set of biological riches, and – perhaps more dangerously – it creates a loss for other species that may in some way depend upon it. Extinction breeds extinction, the authors argue.

And as plants and animals vanish into oblivion, the biosphere’s capacity to recycle atmosphere, water and nutrients, to pollinate and fertilise, and to dispose of the dead and the waste, is diminished.

‘Ecological zombies’

Ecosystems that support and enrich all life also support and enrich humanity. At one stage 60 million bison maintained the prairie ecosystems of North America and in the course of doing so supported the then Native American population.

By 1884 only 325 individuals were left. The prairies are now largely farmland, and the 4000 surviving wild bison can be considered, the authors say, as “ecological zombies.”

Among other steps, they want to see a halt to the trade in wildlife – thought to be linked to the origins of the Covid-19 pandemic. All three have considerable reputations within science and they have all been making much the same argument for many years.

They calculate that in the last century 543 species of land vertebrate were extinguished. The same number could go in the next two decades. Human action created the problem: only human action can repair the damage.

“It’s up to us to decide what kind of a world we want to leave to coming generations – a sustainable one, or a desolate one in which the civilisation we have built disintegrates rather than builds on past successes,” said Peter Raven, president emeritus of the Missouri Botanical Garden, the third of the signatories. – Climate News Network

Threats to the insect world are growing

The insect world is dwindling. By 2100, half of all insects could be gone. But there could be gainers too.

LONDON, 30 April, 2020 − The butterflies are quietly flying away, the beetles are buzzing off, and the insect world is shrinking. The Earth’s  land-based insects are in steady decline, their numbers falling by around a quarter every three decades.

And although there could be a whole world of reasons for the global loss of a vital class of animals, European scientists have pinpointed at least one, in one location.

Insect food plants are being lost in the Swiss canton of Zurich, and with them, many of the hoverflies, bumblebees, bees and butterflies that depend on them.

Scientists from Germany and Russia report in the journal Science that they examined the bigger story told by data from 166 surveys of insects and arachnids – that is, not just flies but spiders too – across 1,676 sites worldwide, over periods from 1925 to 2018, and many of them of around 20 years.

Largely missed

They found that those insects that based their lives on land rather than water were slipping away at an average of 0.92% per year. “0.92% might not sound like much, but in fact it means 24% fewer insects in 30 years’ time and 50% fewer over 75 years,” said Roel van Klink of the German Centre for Integrative Biodiversity Research and based at the University of Leipzig.

“Insect declines happen in a quiet way and we don’t take much notice from one year to the next. It’s like going back to the place where you grew up. It’s only because you haven’t been there for years that you suddenly realise how much has changed, and all too often not for the better.”

He is not the first to draw attention to insect loss: other groups have warned of dramatic instances of decline and imminent extinction, along with the changes in insect populations and the disappearance of the habitat on which so many species depend.

But the researchers found the decline wasn’t uniform. Those insects – midges and mayflies, for example – that are essentially aquatic were actually increasing in number, on average by more than 1% a year. Flying insects overall however are in decline, and ground-dwellers and grassland insects too are slowly losing the battle for survival, while the numbers of insects in the woodland treetops remain about the same.

“Insect declines happen in a quiet way and we don’t take much notice from one year to the next”

Insect declines in Europe and the US West and Midwest were marked, but those insects that live for part of their lives in water in northern Europe and the western US showed a 38% increase over 30 years: this may reflect national and international attempts to limit pollution of the waterways. In both decline and revival, the scientists at work see the impact of human handling of natural habitat.

“Insect populations are like logs of wood that are pushed under water,” Dr van Klink said. “They want to come up while we keep pushing them down. But we can reduce the pressure so they rise again.

“The freshwater insects have shown us this is possible. It’s just not always easy to identify the causes of declines, and thus the most effective measures to reverse them. And these may also differ between locations.”

But within a day of the publication of the Science analysis, German and Swiss scientists had identified the cause of decline in one closely-observed area. They report in the journal Ecological Applications that over the past century there had been an overall decline in wild food plants for all kinds of insects in the Zurich canton.

Urban spread

Wetlands had shrunk by around 90%, the cities and towns had expanded, intensive farming had meant the loss of meadows and farmland habitats.
With help from 250 volunteers, researchers had made detailed studies of the 1,719 seed plant species in 1km plots of land at 3km intervals across the whole canton, between 2012 and 2017.

They then identified 966 of those plants visited by daytime pollinators, and compared their findings with highly-detailed data assembled about the vegetation of the canton before 1930.

Some specialised groups of insects evolved in partnership with equally specialised insects. The scientists found that, for instance, greater knapweed or Centaurea scabiosa was in decline, which was bad news for those bumblebees, bees and butterflies with tongues long enough to reach the nectar. The poisonous plant aconite, or Aconitum napellus, is pollinated by a bumblebee impervious to its toxin. Once again, the loss of floral variety and insect life even in one much-occupied place may not have been obvious.

“It’s hard for us to imagine what vegetation looked like 100 years ago,” said Michael Kessler, a botanist at the University of Zurich. “But our data showed that about half of all species have experienced significant decline in their abundance, while only about 10% of the species have increased.” − Climate News Network

The insect world is dwindling. By 2100, half of all insects could be gone. But there could be gainers too.

LONDON, 30 April, 2020 − The butterflies are quietly flying away, the beetles are buzzing off, and the insect world is shrinking. The Earth’s  land-based insects are in steady decline, their numbers falling by around a quarter every three decades.

And although there could be a whole world of reasons for the global loss of a vital class of animals, European scientists have pinpointed at least one, in one location.

Insect food plants are being lost in the Swiss canton of Zurich, and with them, many of the hoverflies, bumblebees, bees and butterflies that depend on them.

Scientists from Germany and Russia report in the journal Science that they examined the bigger story told by data from 166 surveys of insects and arachnids – that is, not just flies but spiders too – across 1,676 sites worldwide, over periods from 1925 to 2018, and many of them of around 20 years.

Largely missed

They found that those insects that based their lives on land rather than water were slipping away at an average of 0.92% per year. “0.92% might not sound like much, but in fact it means 24% fewer insects in 30 years’ time and 50% fewer over 75 years,” said Roel van Klink of the German Centre for Integrative Biodiversity Research and based at the University of Leipzig.

“Insect declines happen in a quiet way and we don’t take much notice from one year to the next. It’s like going back to the place where you grew up. It’s only because you haven’t been there for years that you suddenly realise how much has changed, and all too often not for the better.”

He is not the first to draw attention to insect loss: other groups have warned of dramatic instances of decline and imminent extinction, along with the changes in insect populations and the disappearance of the habitat on which so many species depend.

But the researchers found the decline wasn’t uniform. Those insects – midges and mayflies, for example – that are essentially aquatic were actually increasing in number, on average by more than 1% a year. Flying insects overall however are in decline, and ground-dwellers and grassland insects too are slowly losing the battle for survival, while the numbers of insects in the woodland treetops remain about the same.

“Insect declines happen in a quiet way and we don’t take much notice from one year to the next”

Insect declines in Europe and the US West and Midwest were marked, but those insects that live for part of their lives in water in northern Europe and the western US showed a 38% increase over 30 years: this may reflect national and international attempts to limit pollution of the waterways. In both decline and revival, the scientists at work see the impact of human handling of natural habitat.

“Insect populations are like logs of wood that are pushed under water,” Dr van Klink said. “They want to come up while we keep pushing them down. But we can reduce the pressure so they rise again.

“The freshwater insects have shown us this is possible. It’s just not always easy to identify the causes of declines, and thus the most effective measures to reverse them. And these may also differ between locations.”

But within a day of the publication of the Science analysis, German and Swiss scientists had identified the cause of decline in one closely-observed area. They report in the journal Ecological Applications that over the past century there had been an overall decline in wild food plants for all kinds of insects in the Zurich canton.

Urban spread

Wetlands had shrunk by around 90%, the cities and towns had expanded, intensive farming had meant the loss of meadows and farmland habitats.
With help from 250 volunteers, researchers had made detailed studies of the 1,719 seed plant species in 1km plots of land at 3km intervals across the whole canton, between 2012 and 2017.

They then identified 966 of those plants visited by daytime pollinators, and compared their findings with highly-detailed data assembled about the vegetation of the canton before 1930.

Some specialised groups of insects evolved in partnership with equally specialised insects. The scientists found that, for instance, greater knapweed or Centaurea scabiosa was in decline, which was bad news for those bumblebees, bees and butterflies with tongues long enough to reach the nectar. The poisonous plant aconite, or Aconitum napellus, is pollinated by a bumblebee impervious to its toxin. Once again, the loss of floral variety and insect life even in one much-occupied place may not have been obvious.

“It’s hard for us to imagine what vegetation looked like 100 years ago,” said Michael Kessler, a botanist at the University of Zurich. “But our data showed that about half of all species have experienced significant decline in their abundance, while only about 10% of the species have increased.” − Climate News Network