̽��ֱ�� of Cambridge - Andrew Tanentzap

Natural clean-up: bacteria can remove plastic pollution from lakes

jg533 — Tue, 26 Jul 2022 15:18:01 +0000

̽��ֱ��bacteria break down the carbon compounds in plastic to use as food for their growth.

̽��ֱ��scientists say that enriching waters with particular species of bacteria could be a natural way to remove plastic pollution from the environment.

̽��ֱ��effect is pronounced: the rate of bacterial growth more than doubled when plastic pollution raised the overall carbon level in lake water by just 4%.

̽��ֱ��results suggest that the plastic pollution in lakes is ‘priming’ the bacteria for rapid growth – the bacteria are not only breaking down the plastic but are then more able to break down other natural carbon compounds in the lake.

Lake bacteria were found to favour plastic-derived carbon compounds over natural ones. ̽��ֱ��researchers think this is because the carbon compounds from plastics are easier for the bacteria to break down and use as food.

̽��ֱ��scientists caution that this does not condone ongoing plastic pollution. Some of the compounds within plastics can have toxic effects on the environment, particularly at high concentrations.

̽��ֱ��findings are published today in the journal Nature Communications.

“It’s almost like the plastic pollution is getting the bacteria’s appetite going. ̽��ֱ��bacteria use the plastic as food first, because it’s easy to break down, and then they’re more able to break down some of the more difficult food – the natural organic matter in the lake,” said Dr Andrew Tanentzap in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences, senior author of the paper.

He added: “This suggests that plastic pollution is stimulating the whole food web in lakes, because more bacteria means more food for the bigger organisms like ducks and fish.”

̽��ֱ��effect varied depending on the diversity of bacterial species present in the lake water – lakes with more different species were better at breaking down plastic pollution.

A study published by the authors last year found that European lakes are potential hotspots of microplastic pollution.

When plastics break down they release simple carbon compounds. ̽��ֱ��researchers found that these are chemically distinct to the carbon compounds released as organic matter like leaves and twigs break down.

̽��ֱ��carbon compounds from plastics were shown to be derived from additives unique to plastic products, including adhesives and softeners.

̽��ֱ��new study also found that bacteria removed more plastic pollution in lakes that had fewer unique natural carbon compounds. This is because the bacteria in the lake water had fewer other food sources.

̽��ֱ��results will help to prioritise lakes where pollution control is most urgent. If a lake has a lot of plastic pollution, but low bacterial diversity and a lot of different natural organic compounds, then its ecosystem will be more vulnerable to damage.

“Unfortunately, plastics will pollute our environment for decades. On the positive side, our study helps to identify microbes that could be harnessed to help break down plastic waste and better manage environmental pollution," said Professor David Aldridge in the ̽��ֱ�� of Cambridge’s Department of Zoology, who was involved in the study.

̽��ֱ��study involved sampling 29 lakes across Scandinavia between August and September 2019. To assess a range of conditions, these lakes differed in latitude, depth, area, average surface temperature and diversity of dissolved carbon-based molecules.

̽��ֱ��scientists cut up plastic bags from four major UK shopping chains, and shook these in water until their carbon compounds were released.

At each lake, glass bottles were filled with lake water. A small amount of the ‘plastic water’ was added to half of these, to represent the amount of carbon leached from plastics into the environment, and the same amount of distilled water was added to the others. After 72 hours in the dark, bacterial activity was measured in each of the bottles.

̽��ֱ��study measured bacterial growth - by increase in mass, and the efficiency of bacterial growth - by the amount of carbon-dioxide released in the process of growing.

In the water with plastic-derived carbon compounds, the bacteria had doubled in mass very efficiently. Around 50% of this carbon was incorporated into the bacteria in 72 hours.

"Our study shows that when carrier bags enter lakes and rivers they can have dramatic and unexpected impacts on the entire ecosystem. Hopefully our results will encourage people to be even more careful about how they dispose of plastic waste," said Eleanor Sheridan in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences, first author of the study who undertook the work as part of a final-year undergraduate project.

̽��ֱ��research was funded by the European Research Council.

Reference

Sheridan, EA et al: ‘Plastic pollution fosters more microbial growth in lakes than natural organic matter.’ Nature Communications, 2022. DOI: 10.1038/s41467-022-31691-9

A study of 29 European lakes has found that some naturally-occurring lake bacteria grow faster and more efficiently on the remains of plastic bags than on natural matter like leaves and twigs.

It’s almost like the plastic pollution is getting the bacteria’s appetite going. ̽��ֱ��bacteria use the plastic as food first, because it’s easy to break down.

Andrew Tanentzap

SG Woodman

Study lake in Norway

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Hungry caterpillars an underappreciated driver of carbon emissions

jg533 — Wed, 03 Nov 2021 10:00:08 +0000

Outbreaks of caterpillars of invasive gypsy moths, Lymantria dispar dispar, and forest tent caterpillar moths, Malacasoma disstria occur at least every five years in temperate forests. ̽��ֱ��insects munch through so many leaves that the resulting decrease in leaf-fall and increase in insect excrement has been found to alter the cycling of nutrients, particularly carbon and nitrogen, between land and nearby lakes on a huge scale.

Nitrogen-rich insect excrement, called frass, can wash into lake water and act as fertiliser for microbes, which then release carbon dioxide into the atmosphere as they metabolise. ̽��ֱ��researchers suggest that in outbreak years the large quantities of frass will favour the growth of greenhouse gas-producing bacteria in lakes at the expense of algae that remove CO2 from the atmosphere.

“These insects are basically little machines that convert carbon-rich leaves into nitrogen-rich poo. ̽��ֱ��poo drops into lakes instead of the leaves, and this significantly changes the water chemistry - we think it will increase the extent to which lakes are sources of greenhouse gases,” said Professor Andrew Tanentzap in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences, senior author of the paper.

Northwards range expansion and increased insect population growth is anticipated as the climate changes. This puts northern forests at increased risk of defoliator outbreaks in the future, potentially causing greater quantities of CO2 to be released from nearby lakes.

This northwards shift is also concerning because there are more freshwater lakes further north. And climate change is also expected to favour broadleaved deciduous trees around the lakes, which will amplify the effect of the insects.

̽��ֱ��study found that in years with insect outbreaks, the leaf area of forests was reduced by an average of 22%. At the same time, nearby lakes contained 112% more dissolved nitrogen and 27% less dissolved carbon compared to non-outbreak years. ̽��ֱ��effects were greatest when lake catchments contained higher proportions of deciduous broadleaved trees, such as oaks and maples, which the caterpillars favour over coniferous trees like pines.

To get their results, researchers combined 32 years of government data from insect outbreak surveys and lake water chemistry in 12 lake catchments across Ontario, Canada, and satellite remote sensing data on forest type and monthly leaf area cover. ̽��ֱ��results are published today in the journal Nature Communications.

This is believed to be the most extensive study ever undertaken into how insect outbreaks impact freshwater carbon and nitrogen dynamics. Previous studies have been so small that it has been difficult to extract wider generalities.

A previous 26-year study of 266 lakes across the northern hemisphere has shown that carbon is naturally accumulating in these lake waters, in a process called browning. ̽��ֱ��trend is attributed to a variety of factors including climate change, and recovery from historical acid rain and logging activities. Comparing the new results to this data showed that an outbreak of leaf-munching caterpillars can effectively offset an entire year’s worth of carbon accumulation in nearby lakes – significantly improving water quality.

In years without outbreaks of leaf-eating insects, carbon and nitrogen entering lakes usually comes from decaying leaf and needle litter, and peaks in quantity in autumn. In outbreak years, the study found that nearby freshwater lakes contained an average of 27% less dissolved carbon.

“Outbreaks of leaf-eating insects can reduce the carbon dissolved in lake water by almost a third when the trees around the lake are mainly deciduous. It’s just amazing that these insects can have such a pronounced effect on water quality,” said Sam Woodman, a researcher in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences and first author of the report.

He added: “From a water quality perspective they’re a good thing, but from a climate perspective they’re pretty bad – yet they’ve been completely overlooked in climate models.”

This research was funded by the Natural Environment Research Council (NERC).

Reference

Woodman, S G et al: ‘Forest defoliator outbreaks alter nutrient cycling in northern waters’, Nature Communications, November 2021. DOI: 10.1038/s41467-021-26666-1

A study led by the ̽��ֱ�� of Cambridge has found that periodic mass outbreaks of leaf-munching caterpillars can improve the water quality of nearby lakes - but may also increase the lakes’ carbon dioxide emissions.

From a water quality perspective they’re a good thing, but from a climate perspective they’re pretty bad

Sam Woodman

Outbreak of leaf-eating caterpillars

Yes

European lakes potential hotspots of microplastic pollution

jg533 — Tue, 14 Sep 2021 18:52:18 +0000

A study published today in the journal PLOS Biology suggests that human activity and land use in areas surrounding lakes drive significant microplastic pollution in lake water.

Going up: birds and mammals evolve faster if their home is rising

jg533 — Thu, 02 Sep 2021 15:11:37 +0000

Researchers at the ̽��ֱ�� of Cambridge have combined reconstructions of the Earth’s changing surface elevations over the past three million years with data on climate change over this timeframe, and with bird and mammal species’ locations. Their results reveal how species evolved into new ones as land elevation changed - and disentangle the effects of elevation from the effects of climate.

̽��ֱ��study found that the effect of elevation increase is greater than that of historical climate change, and of present-day elevation and temperature, in driving the formation of new species – ‘or speciation’.

In contrast to areas where land elevation is increasing, elevation loss was not found to be an important predictor of where speciation happens. Instead, present-day temperature is a better indicator of speciation in these areas.

̽��ֱ��results are published today in the journal Nature Ecology and Evolution.

“Often at the tops of mountains there are many more unique species that aren’t found elsewhere. Whereas previously the formation of new species was thought to be driven by climate, we’ve found that elevation change has a greater effect at a global scale,” said Dr Andrew Tanentzap in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences, senior author of the paper.

As land elevation increases, temperature generally decreases and habitat complexity increases. In some cases, for example where mountains form, increasing elevation creates a barrier that prevents species moving and mixing, so populations become reproductively isolated. This is the first step towards the formation of new species.

̽��ֱ��effect of increasing elevation on that rate of new species formation over time was more pronounced for mammals than for birds; the researchers think this is because birds can fly across barriers to find mates in other areas. Birds were affected more by present-day temperatures; in birds, variation in temperature creates differences in the timing and extent of mating, risking reproductive isolation from populations of the same species elsewhere.

Until now, most large-scale studies into the importance of topography in generating new species have only considered present-day land elevation, or elevation changes in specific mountain ranges.

“It’s surprising just how much effect historical elevation change had on generating the world’s biodiversity – it has been much more important than traditionally studied variables like temperature. ̽��ֱ��rate at which species evolved in different places on Earth is tightly linked to topography changes over millions of years,” said Dr Javier Igea in the ̽��ֱ�� of Cambridge’s Department of Plant Sciences, first author of the paper.

He added: “This work highlights important arenas for evolution to play out. From a conservation perspective these are the places we might want to protect, especially given climate change. Although climate change is happening over decades, not millions of years, our study points to areas that can harbour species with greater potential to evolve.”

̽��ֱ��researchers say that as the Earth’s surface continues to rise and fall, topography will remain an important driver of evolutionary change.

This research was funded by Wellcome, the Gatsby Charitable Foundation and the Isaac Newton Trust.

Reference

Igea, J. & Tanentzap, A.J.: ‘Global topographic uplift has elevated speciation in mammals and birds over the last 3 million years.’ Nature Ecology & Evolution, September 2021. DOI: 10.1038/s41559-021-01545-6

̽��ֱ��rise and fall of Earth’s land surface over the last three million years shaped the evolution of birds and mammals, a new study has found, with new species evolving at higher rates where the land has risen most.

Whereas previously the formation of new species was thought to be driven by climate, we’ve found that elevation change has a greater effect at a global scale

Andrew Tanentzap

Pablo Heimplatz on Unsplash

Wild Kea, New Zealand

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Climate change could double greenhouse gas emissions from freshwater ecosystems

jg533 — Mon, 18 Nov 2019 20:00:00 +0000

Small shallow lakes dominate the world’s freshwater area, and the sediments within them already produce at least one-quarter of all carbon-dioxide, and more than two-thirds of all methane that come from lakes. ̽��ֱ��new research, published in the journal PNAS, suggests that climate change may cause the levels of greenhouse gases emitted by freshwater northern lakes to increase by between 1.5 and 2.7 times.

“What we’ve traditionally called ‘carbon’ in freshwater turns out to be a super-diverse mixture of different carbon-based organic molecules,” said Dr Andrew Tanentzap in Cambridge’s Department of Plant Sciences, who led the research. “We’ve been measuring ‘carbon’ in freshwater as a proxy for everything from water quality to the productivity of freshwater ecosystems. Now we’ve realised that it’s the diversity of this invisible world of organic molecules that’s important.”

As the climate warms, vegetation cover is increasing in forests of the northern latitudes. By simulating this effect in two lakes in Ontario, Canada, the study found an increased diversity of organic molecules – molecules containing carbon within their structure – entering the water in the matter shed by nearby plants and trees.

Organic molecules are a food source for microbes in the lake sediments, which break them down and release carbon dioxide and methane as by-products. Increasing levels of organic molecules can therefore enhance microbial activity and produce more greenhouse gases.

Since the same microbes can make greenhouse gases from many different organic molecules, the diversity of organic molecules was shown to be more closely linked with levels of greenhouse gas concentrations than the diversity of the microbes. In addition, an elevated diversity of organic molecules may elevate greenhouse gas concentrations in waters because there are more molecules that can be broken down by sunlight penetrating the water.

To conduct the research, containers were filled with varying ratios of rocks and organic material - consisting of deciduous and coniferous litter from nearby forests - and submerged in the shallow waters of the two lakes. Analysis of the samples two months later, using the techniques of ultrahigh resolution mass spectrometry and next generation DNA sequencing, showed that the diversity of organic molecules was correlated with the diversity of microbial communities in the water, and that the diversity of both increased as the amount of organic matter increased.

Accurately predicting carbon emissions from natural systems is vital to the reliability of calculations used to understand the pace of climate change, and the effects of a warmer world.

“Climate change will increase forest cover and change species composition, resulting in a greater variety of leaves and plant litter falling into waterways. We found that the resulting increase in the diversity of organic molecules in the water leads to higher greenhouse gas concentrations,” said Tanentzap. “Understanding these connections means we could look at ways to reduce carbon emissions in the future, for example by changing land management practices.”

Changing the vegetation around freshwater areas could change the organic molecules that end up in the water. ̽��ֱ��team is now expanding their study by taking samples from 150 lakes across Europe, to understand the broader ecological consequences of organic molecule diversity in natural freshwater systems.

This research was funded by the Natural Environment Research Council.

Reference

Tanentzap, A. J. et al: ‘Chemical and microbial diversity covary in fresh water to influence ecosystem functioning.' PNAS (2019). DOI: 10.1073/pnas.1904896116

Every drop of fresh water contains thousands of different organic molecules that have previously gone unnoticed. By measuring the diversity of these molecules and how they interact with the environment around them, research has revealed an invisible world that affects the functioning of freshwater ecosystems and can contribute to greenhouse gas emissions.

What we’ve traditionally called ‘carbon’ in freshwater turns out to be a super-diverse mixture of different carbon-based organic molecules.

Andrew Tanentzap

Jondolar Schnurr on Pixabay

Canadian lake

Yes

Species ‘hotspots’ created by immigrant influx or evolutionary speed depending on climate

fpjl2 — Wed, 06 Feb 2019 19:01:52 +0000

Some corners of the world teem with an extraordinary variety of life. Charles Darwin noted that: “ ̽��ֱ��same spot will support more life if occupied by very diverse forms.”

̽��ֱ��question of how these ‘hotspots’ of biodiversity – from California to the Galapagos – acquired such a wealth of species has long puzzled naturalists.

Now, scientists at the ̽��ֱ�� of Cambridge have conducted a ‘big data’ study of almost all the world’s mammal and bird species to reveal the answer – and it’s very different depending on climate.

According to the study, tropical hotspots close to the equator have generated new species at a much faster rate than their surrounding areas during the last 25 million years of evolution.

However, biodiversity hotspots in more temperate northerly regions, such as the Mediterranean basin and Caucasus Mountains, are mainly populated with immigrant species that originated elsewhere.

Scientists say these migrants may have been escaping the effects of long-term “geological processes” such as vast encroaching glaciers. Warmer climes, as well as peninsulas and mountain ranges, could have offered shelter.

̽��ֱ��researchers say that their new study, published today in the journal Science Advances, shows how these “contrasting macroevolutionary routes” have shaped the uneven distribution of species across the planet.

“We’ve known for decades that just a subset of places on Earth, no more than 20%, contain about half of all vertebrate species. However, we lacked the tools and data to understand why these patterns exist,” said senior author Dr Andrew Tanentzap, from Cambridge’s Department of Plant Sciences.

“Large-scale initiatives to map species across the planet and in the Tree of Life, as well as advances in computing, are expanding our understanding of evolution in exciting ways. This study can now provide an answer to the old question of why diversity varies so much across the world.”

Cambridge scientists used new computational techniques to combine several giant datasets. These included the global distribution of 11,093 bird species and 5,302 mammals, and detailed evolutionary trees that track the origin of thousands of organisms through deep time.

In this way, the researchers were able to analyse the development of particularly species-rich areas within each of the Earth’s great “biogeographical regions” – from Australasia to the Nearctic.

They found that biodiversity hotspots in the tropics, such as South American forests and Indonesian islands, had higher rates of “speciation” – the formation of new and distinct species – over the last 25 million years.

For example, speciation rates for birds in hotspots of the Indo-Malay region were, on average, 36% higher than that region’s non-hotspot areas. Hotspots in the Neotropics had almost 28% greater bird speciation compared to non-hotspots.

“Species generation is faster in the tropics, but we can now see it is extra-quick in these hotspots of biodiversity,” said study lead author Dr Javier Igea, also from Cambridge’s Department of Plant Sciences.

“More rainfall and hotter temperatures bolster the ecosystems of tropical hotspots, producing more plants, more animals that feed on those plants, and so on,” he said.

“ ̽��ֱ��greater available energy and range of habitats within these hotspots supported the acceleration of species diversification.”

̽��ֱ��tropical hotspot of Madagascar, for example, holds 12 species of true lemur that diversified in the last ten million years. All of the 17 species of earthworm mice endemic to the Philippines were generated in the last six million years.

̽��ֱ��famously diverse finches Darwin found in the Galapagos Islands, as featured in his revolutionary book On the Origin of Species, are an iconic example of rapid speciation in a tropical hotspot.

However, when it came to the more temperate regions of the Nearctic (North America) and Palearctic (Eurasia and North Africa), the researchers discovered a different story.

While the hotspots of these regions also had a wider range of resource and habitat than neighbouring areas, the data from the evolutionary – or phylogenetic – trees revealed that most of their animals “speciated” somewhere else.

“Biodiversity hotspots in temperate zones have been shaped mainly by migration that occurred during the last 25 million years,” said Igea.

“We suspect that this influx of immigrant species resulted from climate fluctuations across millions of years, particularly cooling. Biodiversity hotspots may have acted as a refuge where more species could survive in harsh climatic conditions,” he said.

Igea points to species such as the Iberian lynx, now a native of the Mediterranean Basin hotspot, but found in central Europe during the Pleistocene – prior to the last Ice Age.

Or the yellow-billed magpie, which became isolated in California after becoming separated from its ancestral species – most likely due to glaciations – over three million years ago.

“We found that hotspots across the world all have a greater complexity of habitats and more environmental energy, but the processes that drive the biodiversity are very different for tropical and temperate zones,” Igea said.

For Tanentzap, the importance of species migration in temperate regions suggests that maintaining connectivity between hotspots should be a priority for future conservation efforts.

“Many of these hotspot regions have species found nowhere else on Earth, yet face devastating levels of habitat loss. Protecting these areas is vital to conserving the natural world’s diversity,” he said.

Reference
Igea, J et al. Multiple macroevolutionary routes to becoming a biodiversity hotspot. Science Advances; 6 Feb 2019; DOI: 10.1126/sciadv.aau8067

A bold response to the world’s greatest challenge
̽��ֱ�� ̽��ֱ�� of Cambridge is building on its existing research and launching an ambitious new environment and climate change initiative. Cambridge Zero is not just about developing greener technologies. It will harness the full power of the ̽��ֱ��’s research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

New research reveals that biodiversity ‘hotspots’ in the tropics produced new species at faster rates over the last 25 million years, but those in temperate regions are instead full of migrant species that likely sought refuge from shifting and cooling climates.

Many of these hotspot regions have species found nowhere else on Earth, yet face devastating levels of habitat loss

Andrew Tanentzap

Museum of Zoology / Chris Green

Galapagos finch specimens from Museum of Zoology, collected on the second voyage of HMS Beagle that carried Darwin to the Islands. Researchers say these famously diverse finches are an iconic example of rapid speciation in the tropics.

Yes

Greenhouse gas ‘feedback loop’ discovered in freshwater lakes

fpjl2 — Fri, 04 May 2018 09:00:06 +0000

A new study of chemical reactions that occur when organic matter decomposes in freshwater lakes has revealed that the debris from trees suppresses production of methane – while debris from reed beds actually promotes this harmful greenhouse gas.

As vegetation in and around bodies of water continues to change, with forest cover being lost while global warming causes wetland plants to thrive, the many lakes of the northern hemisphere – already a major source of methane – could almost double their emissions in the next fifty years.

̽��ֱ��researchers say that the findings suggest the discovery of yet another “feedback loop” in which environmental disruption and climate change trigger the release of ever more greenhouse gas that further warms the planet, similar to the concerns over the methane released by fast-melting arctic permafrost.

“Methane is a greenhouse gas at least twenty-five times more potent than carbon dioxide. Freshwater ecosystems already contribute as much as 16% of the Earth’s natural methane emissions, compared to just 1% from all the world’s oceans,” said study senior author Dr Andrew Tanentzap, from the ̽��ֱ�� of Cambridge’s Department of Plant Sciences.

“We believe we have discovered a new mechanism that has the potential to cause increasingly more greenhouse gases to be produced by freshwater lakes. ̽��ֱ��warming climates that promote the growth of aquatic plants have the potential to trigger a damaging feedback loop in natural ecosystems.”

̽��ֱ��researchers point out that the current methane emissions of freshwater ecosystems alone offsets around a quarter of all the carbon soaked up by land plants and soil: the natural ‘carbon sink’ that drains and stores CO2 from the atmosphere.

Up to 77% of the methane emissions from an individual lake are the result of the organic matter shed primarily by plants that grow in or near the water. This matter gets buried in the sediment found toward the edge of lakes, where it is consumed by communities of microbes. Methane gets generated as a byproduct, which then bubbles up to the surface.

Working with colleagues from Canada and Germany, Tanentzap’s group found that the levels of methane produced in lakes varies enormously depending on the type of plants contributing their organic matter to the lake sediment. ̽��ֱ��study, funded by the UK’s Natural Environment Research Council, is published today in the journal Nature Communications.

To test how organic matter affects methane emissions, the scientists took lake sediment and added three common types of plant debris: deciduous trees that shed leaves annually, evergreen pine-shedding coniferous trees, and cattails (often known in the UK as ‘bulrushes’) – a common aquatic plant that grows in the shallows of freshwater lakes.

These sediments were incubated in the lab for 150 days, during which time the scientists siphoned off and measured the methane produced. They found that the bulrush sediment produced over 400 times the amount of methane as the coniferous sediment, and almost 2,800 times the methane than that of the deciduous.

Unlike the cattail debris, the chemical makeup of the organic matter from trees appears to trap large quantities of carbon within the lake sediment – carbon that would otherwise combine with hydrogen and get released as methane into the atmosphere.

To confirm their findings, the researchers also “spiked” the three samples with the microbes that produce methane to gauge the chemical reaction. While the forest-derived sediment remained unchanged, the sample containing the bulrush organic matter doubled its methane production.

“ ̽��ֱ��organic matter that runs into lakes from the forest trees acts as a latch that suppresses the production of methane within lake sediment. These forests have long surrounded the millions of lakes in the northern hemisphere, but are now under threat,” said Dr Erik Emilson, first author of the study, who has since left Cambridge to work at Natural Resources Canada.

“At the same time, changing climates are providing favourable conditions for the growth and spread of aquatic plants such as cattails, and the organic matter from these plants promotes the release of even more methane from the freshwater ecosystems of the global north.”

Using species distribution models for the Boreal Shield, an area that covers central and eastern Canada and “houses more forests and lakes than just about anywhere on Earth”, the researchers calculated that the number of lakes colonised by just the common cattail (Typha latifolia) could double in the next fifty years – causing current levels of lake-produced methane to increase by at least 73% in this part of the world alone.

Added Tanentzap: “Accurately predicting methane emissions is vital to the scientific calculations used to try and understand the pace of climate change and the effects of a warmer world. We still have limited understanding of the fluctuations in methane production from plants and freshwater lakes.”

Latest research finds plant debris in lake sediment affects methane emissions. ̽��ֱ��flourishing reed beds created by changing climates could threaten to double the already significant methane production of the world’s northern lakes.

̽��ֱ��warming climates that promote the growth of aquatic plants have the potential to trigger a damaging feedback loop in natural ecosystems

Andrew Tanentzap

Andrew Tanentzap.

Lake near Sudbury, Ontario, in the Canadian Boreal Shield, with aquatic plants in the foreground providing fuel for methane production.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Paying farmers to help the environment works, but ‘perverse’ subsidies must be balanced

sc604 — Wed, 09 Sep 2015 18:00:00 +0000

New research suggests that offering financial incentives for farming industries to mitigate the impact agriculture has on the environment, by reducing fertiliser use and ‘sparing’ land for conservation, for example, actually has a positive effect on critical areas such as greenhouse gas reduction and increased biodiversity.

It has been a point of contention whether such ‘cash for conservation’ initiatives succeed. For the latest study, researchers aggregated investment in environmental incentives at a national level for the first time, and, by comparing them to broad trends in environmental outcomes, found that paying the agriculture industry to help the environment seems to be working.

However, the research team also mapped the proportion of global agricultural production reinvested in environmental incentives, and compared it to the proportion gifted to the industry through government subsidies. As expressed in pie charts, the results show big wedges of subsidy stacked on top of barely perceptible slivers of environmental investment.

For example, around 20% of the value of agriculture production in the EU is subsidised by the taxpayer. However, less than 1% goes towards mitigating the toll farming takes on the natural world – despite agriculture contributing more to environmental degradation than any other economic sector, say researchers.

̽��ֱ��team describe current agriculture funding models as ‘perverse subsidies’: promoting negative actions in both the long and short term by being bad for the environment and costly to the economy.

They argue for a redressing of the massive imbalance between government money spent on farming subsidies, and that spent on lessening the damage farming does to the environment.

Consumption of environmental services, such as water (crop irrigation alone counts for 70% of the world’s freshwater withdrawals), should be taxed, say the researchers, and any subsidies should be paid on the proviso that they are as much for protecting the land as for farming it.

“Our results show that paying farmers to do things that are good for the environment actually seems to work when averaged across national scales,” said lead author Dr Andrew Tanentzap.

“In many parts of the world, governments already provide huge subsidies to the agriculture industry; if we are paying people to be farmers, part of that payment – indeed, part of the job of a farmer – needs to be protecting the countryside as well as farming it,” he said. “We need a shift in what it means to be a farmer.”

̽��ֱ��work, conducted by researchers from Cambridge ̽��ֱ��’s departments of Plant Sciences and Zoology, is published today in the open access journal PLOS Biology.

While national data for environmental performance is limited and difficult to quantify, the research team were able to plot investment in two key agri-environment schemes, land ‘retirement’ for conservation and limiting fertiliser use, against national trends for farmland bird populations and emissions from synthetic fertiliser across landmasses including the US, Canada, Australia and Europe.

They found that, broadly speaking, higher national investment in these environmentally-friendly incentive schemes over a five-year period correlated with increased levels of bird biodiversity and lower rates of gas emissions from farming.

“There’s controversy around whether such environmental incentives actually work at a local scale. What we’ve done is average out the local effects to pull out what’s happening on a very large scale, and it looks like there are benefits to paying farmers to be kinder to the environment,” said Tanentzap.

However, Tanentzap points out that paying farmers to be more environmentally-friendly won’t solve the problem of food security, and if these schemes reduce crop yields it may result in increased production elsewhere: “displacing the impacts that we are paying some farmers to mitigate”. He says that, in the worst cases, this results in further land being sucked into the agricultural churn.

“A result of many agri-environment schemes is the spreading out – or ‘sharing’ – of land for both farming and the natural environment. A lot of research, much of it driven by conservation scientists here in Cambridge, shows that this is less effective than simply removing the land from production – ‘sparing’ it for conservation.”

“ ̽��ֱ��most logical solution would be to intensify production on existing lands, trying to minimise environmental impacts with regulations, incentives for good environmental performance, or consumption taxes, while protecting land elsewhere for conservation,” Tanentzap said.

̽��ֱ��researchers say that tackling the huge disparity between government subsidies and environmental incentives needs to be the first step in reducing conflict between agriculture and the natural environment, something they say has traditionally been difficult to achieve because of the power behind agri-food lobbies.

They write that while governments continue to subsidise production and famers are not accountable for the costs of their actions because associated penalties are trivial, damaging the environment will remain highly financially lucrative – with devastating consequences.

However, simply removing subsidies alone fails to reduce environmental harm, and incentives for better farming practices are still required. In the paper, researchers look at the case of New Zealand, where there are no subsidies or mitigation schemes, and much of the country has been transformed into a massive dairy farm for China as a result, says Tanentzap.

“Subsidies for production date from the post-war era, when feeding a booming population was paramount. Food security is, of course, still a major issue as populations continue to rise, but there are ways to deliver this without destroying the planet,” Tanentzap said.

“If the agriculture industry is to be subsidised, then paying farmers to protect the environment – rather than just stripping as much use from the land as possible – is something our study has shown to be effective, and something the natural world is in dire need of.”

Reference:
Tanentzap AJ, Lamb A, Walker S, Farmer A (2015) Resolving Conflicts between Agriculture and the Natural Environment. PLoS Biol 13(9): e1002242. doi:10.1371/journal.pbio.1002242

First analysis of effectiveness of agri-environment schemes measured at a national level suggests that they work, but are still a drop in the ocean compared to huge government subsidies received by farming industries for environmentally damaging practices.

Part of the job of a farmer – needs to be protecting the countryside as well as farming it

Andrew Tanentzap

Peter Scott

Vast pivot irrigator shows farming encroaching on wilderness in New Zealand.

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