Category: Biodiversity

Insects will struggle to keep pace with global temperature rise – which could be bad news for humans

Posted on by janet.crompton

Animals can only endure temperatures within a given range. The upper and lower temperatures of this range are called its critical thermal limits. As these limits are exceeded, an animal must either adjust or migrate to a cooler climate.

However, temperatures are rising across the world at a rapid pace. The record-breaking heatwaves experienced across Europe this summer are indicative of this. Heatwaves such as these can cause temperatures to regularly surpass critical thermal limits, endangering many species.

In a new study, my colleagues and I assessed how well 102 species of insect can adjust their critical thermal limits to survive temperature extremes. We found that insects have a weak capacity to do so, making them particularly vulnerable to climate change.

The impact of climate change on insects could have profound consequences for human life. Many insect species serve important ecological functions while the movement of others can disrupt the balance of ecosystems.

How do animals adjust to temperature extremes?

An animal can extend its critical thermal limits through either acclimation or adaptation.

Acclimation occurs within an animal’s lifetime (often within hours). It’s the process by which previous exposure helps give an animal or insect protection against later environmental stress. Humans acclimate to intense UV exposure through gradual tanning which later protects skin against harmful UV rays.

One way insects acclimate is by producing heat shock proteins in response to heat exposure. This prevents cells dying under temperature extremes.

A ladybird drinking a speck of water on a narrow leaf.
Insects in warmer environments develop fewer spots to reduce heat retention.
mehmetkrc/Shutterstock

Some insects can also use colour to acclimate. Ladybirds that develop in warm environments emerge from the pupal stage with less spots than insects that develop in the cold. As darker spots absorb heat, having fewer spots keeps the insect cooler.

Adaptation occurs when useful genes are passed through generations via evolution. There are multiple examples of animals evolving in response to climate change.

Over the past 150 years, some Australian parrot species such as gang-gang cockatoos and red-rumped parrots have evolved larger beaks. As a greater quantity of blood can be diverted to a larger beak, more heat can be lost into the surrounding environment.

A colourful red-rumped parrot perched on a branch.
The red-rumped parrot has evolved a larger beak to cope with higher temperatures.
Alamin-Khan/Shutterstock

But evolution occurs over a longer period than acclimation and may not allow critical thermal limits to adjust in line with the current pace of global temperature rise. Upper thermal limits are particularly slow to evolve, which may be due to the large genetic changes required for greater heat tolerance.

Research into how acclimation might help animals survive exceptional temperature rise has therefore become an area of growing scientific interest.

A weak ability to adjust to temperature extremes

When exposed to a 1℃ change in temperature, we found that insects could only modify their upper thermal limit by around 10% and their lower limit by around 15% on average. In comparison, a separate study found that fish and crustaceans could modify their limits by around 30%.

But we found that there are windows during development where an insect has a greater tolerance towards heat. As juvenile insects are less mobile than adults, they are less able to use their behaviour to modify their temperature. A caterpillar in its cocoon stage, for example, cannot move into the shade to escape the heat.

Exposed to greater temperature variations, this immobile life stage has faced strong evolutionary pressure to develop mechanisms to withstand temperature stress. Juvenile insects generally had a greater capacity for acclimating to rising temperatures than adult insects. Juveniles were able to modify their upper thermal limit by 11% on average, compared to 7% for adults.

But given that their capacity to acclimate is still relatively weak and may fall as an insect leaves this life stage, the impact is likely to be limited for adjusting to future climate change.

What does this mean for the future?

A weak ability to adjust to higher temperatures will mean many insects will need to migrate to cooler climates in order to survive. The movement of insects into new environments could upset the delicate balance of ecosystems.

Insect pests account for the loss of 40% of global crop production. As their geographical distribution changes, pests could further threaten food security. A UN report from 2021 concluded that fall armyworm populations, which feed on crops such as maize, have already expanded their range due to climate change.

A damaged corn crop following an attack by fall armyworms.
The fall armyworm is a damaging crop pest which is spreading due to climate change.
Alchemist from India/Shutterstock

Insect migration may also carry profound impacts on human health. Many of the major diseases affecting humans, including malaria, are transmitted by insects. The movement of insects over time increases the possibility of introducing infectious diseases to higher latitudes.

There have been over 770 cases of West Nile virus recorded in Europe this year. Italy’s Veneto region, where the majority of the cases originate, has emerged as an ideal habitat for Culex mosquitoes, which can host and transmit the virus. Earlier this year, scientists found that the number of mosquitoes in the region had increased by 27%.

Insect species incapable of migrating may also become extinct. This is of concern because many insects perform important ecological functions. Three quarters of the crops produced globally are fertilised by pollinators. Their loss could cause a sharp reduction in global food production.

The vulnerability of insects to temperature extremes means that we face an uncertain and worrying future if we cannot curb the pace of climate change. A clear way of protecting these species is to slow the pace of climate change by reducing fossil fuel consumption. On a smaller scale, the creation of shady habitats, which contain cooler microclimates, could provide essential respite for insects facing rising temperatures.The Conversation

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This blog is written by Hester Weaving, PhD Candidate in Entomology, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hester Weaving

 

 

The night is full of animal life, but scientists know very little about it

Posted on by janet.crompton

 

Naturalists and life scientists have long debated how insect-eating bats navigate their dark world.
Sarun T/Shutterstock

Human disturbance is rapidly changing the nature of the nocturnal world. Intensive farming, suburban spread, artificially lit cities, and continuously busy road systems mean daytime species are becoming increasingly active throughout the night. Ecologists suggest that the majority of land animals are either nocturnal or active across both the day and night.

Recent research has also shown that the night is warming considerably faster than the day. The stifling night-time heat experienced across Europe this summer is indicative of this, placing nocturnal animals under even greater stress.

The transforming night adds new sensory pressures concerning finding food, a mate, and navigating a world permeated by artificial illumination. Environmental change is severely threatening the ability of nocturnal animals to coexist with humans. The conservation of nocturnal species has therefore become urgent.

Despite the abundance of night-time life, the understanding of nocturnal species has evaded science throughout history. Physical restraints on human navigation in the dark are partially responsible for this. This scientific blind spot is referred to as the “nocturnal problem”.

The legacy of this inaccessibility remains a barrier to our understanding of nocturnal life today. However, given the environmental threat now facing the nocturnal world, this will have profound consequences should it remain unaddressed. A better understanding of nocturnal life is critical to ensure its effective protection.

The origins of the ‘nocturnal problem’

So how did the nocturnal problem arise and why does it still impede science?

Constrained by their own reliance on vision, early scientists struggled to imagine the different ways in which animals might navigate in the dark. The myths that built up around familiar nocturnal creatures, such as hedgehogs, are evidence of historical attempts to fill the scientific gap.

The Greek philosopher Aristotle suggested that hedgehogs poached apples and carried them off on their spines. Such mythology was commonly included within Victorian natural history texts as an introduction to more factual descriptions of hedgehog anatomy, such as their capacity for smell and other bodily adaptations.

A hedgehog passing a road with a car light illuminating the background.
Even the experiences of hedgehogs remain to some degree unknown.
Lukasz Walas/Shutterstock

But even artificial illumination afforded very limited access. Illumination fundamentally changes the nature of the nocturnal world, with impacts on animal behaviour. A good example is the attraction of moths to street lights.

The historical debate surrounding how insect-eating bats navigate their dark world illustrates the problem. Numerous attempts have been made to understand bat senses. However, it was not until the late 1930s, more than 150 years after experimentation on bats had begun, that the scientists Donald R. Griffin and Robert Galambos identified echolocation – the ability to navigate via the emission and detection of sound signals.

Griffin would later describe the secrets of bat senses as a “magic well”, acknowledging the fundamental challenge of comprehending senses so different from our own.

But efforts to understand nocturnal senses could only take scientists so far. In 1940, American naturalist Orlando Park declared that the biological sciences suffered from a “nocturnal problem”, in reference to the continued inability to understand the nocturnal world. This was reflected in the more recent philosophical text of Thomas Nagel, which posed the question what it like is to like to be a bat?

Persistence of the nocturnal problem

Despite technological developments, including the introduction of infrared photography, aspects of nocturnal life continue to elude modern science.

While technology has afforded scientists a much better understanding of echolocation in bats, our way of thinking about bat senses remains limited by our own dependence on vision. When describing echolocation, scientists still suggest that bats “see” using echoes.

The elusive Australian Night Parrot was presumed extinct for much of the 20th century. Although they have been recently rediscovered, scientists remain unable to estimate their population size accurately while questions over the threats facing the species persist.

Despite an improvement in scientific research, nocturnal life remains understudied. In 2019, life scientist Kevin J. Gaston called for an expansion of research into nocturnal life. History shows us that when there are scientific gaps in knowledge about the night, cultures create their own truths to fill those gaps. The consequences of doing so may be significant.

The night is ecologically rich and efforts to fill these gaps in scientific understanding should be prioritised. The nocturnal world is threatened by environmental change, and its future depends on our commitment to getting to know the darkness.The Conversation

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This blog is written by Cabot Institute for the Environment members, Dr Andy Flack, Senior Lecturer in Modern and Environmental History, University of Bristol and Dr Alice Would, Lecturer in Imperial and Environmental History, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Farmer of Myddfai

Posted on by janet.crompton

Above the village of Myddfai, Escairllaethdy Farm stretches over 150 acres. The farm, which lies on the western edge of the Brecon Beacons at the foot of the Black Mountains, has been in Hywel Morgan’s family since his grandfather bought it after the Second World War. It’s an upland livestock farm, and Hywel also has grazing rights on the common land on Mynydd Myddfai for his sheep, horses, and, more recently, cattle. He describes himself as a hill farmer, and one who is especially passionate about the hills.

For the past five years Hywel has been gradually reducing the impact of his farming methods on the land. In an interview in March 2022, he told me more about how this came about. In the wake of Brexit, Hywel met with a Welsh civil servant and asked him what was really required of farmers in this new political context. The reply was that what the Government wanted was for farmers to farm “with nature”. This set Hywel on a journey of discovery that included a study-tour with the Farming Connect Management and Exchange scheme, investigating low-impact farming in Britain and continental Europe, as well as a visit to the Food and Farming conference in Aberystwyth, where he found disappointingly few farmers but did discover a stand for the Nature Friendly Farming Network. He decided to get involved.

Hywel’s move into lower-impact, nature-friendly farming has had a number of practical results. One is in the amount of hedgerow now on the farm. He explained: “I’ve put in about a thousand metres of double fencing every year for the past five years for hedgerow restoration, whether that is planting new hedges, coppicing hedges, or hedge-laying”. He has also been letting the hedges grow taller, sometimes leaving them for three years before cutting them. He says with a sense of pride, “All of a sudden I saw all these birds around in later winter”.  The beneficial effects of the hedges are visible in the summer too, reflected in the behaviour of the livestock. Hywel has noticed that on hot summer days his sheep and cows hide in the shade of the hedges, “and when the sun moves they move with the shade”. He adds, “Watching your animals tells you a lot”. He has also given up using artificial fertiliser and cut down on pharmaceuticals. Where he used to spray off a field of grass with Roundup and drill swedes for the sheep, he now conserves the grass for winter feed.

Farming in a nature-friendly way has involved some changes in the kind of livestock Hywel keeps on the land. He has introduced Highland cattle to his herd, and practises conservation grazing with all of his cattle. The Highlands live up on the hill and Hywel can already see how this stimulates greater biodiversity. In this respect cattle do better than sheep, “because sheep will nibble the short sweet grass right down. The cattle will just trample it for a start, and by trampling it they’re putting organic matter back into the soil and regenerating it a bit”. The hoof impact helps to create habitat for invertebrates and the browsing methods of the cattle “will leave a bit more over for nature”.

How much to leave for nature is a potentially difficult question given that farms are businesses and need to be run as such. Hywel admits that “production-wise it isn’t fantastic because you’re producing less meat per acre or per hectare”, but he argues with great conviction that “we have to have this balance of food production and nature – biodiversity and wildlife – and finding the sweet spot between biodiversity and productivity is key”.

Hywel’s relationship with this landscape is steeped in its history as well as invested in its future. Myddfai is a kind of hallowed ground, the ancient home of the legendary Lady of the Lake and the Physicians of Myddfai, The story of the mysterious Lady and her children, who began a tradition of healers in the village that continued for hundreds of years, was included in The Red Book of Hergest which dates from the late 14th century. Among other tales, the manuscript tells the story of the son of a famer killed fighting to preserve the independence of Wales, who while wandering along the edge of Llyn y Fan Fach, saw a beautiful woman sitting on the surface of the lake. He fell in love with her and wooed her with gifts of bread. On the third occasion, with the bread cooked exactly to her liking, the woman agreed to marry him and stay with him “until she received from him three blows, without any cause”.[i] It was a long time before the man landed the third blow on his wife, but true to her word, she left him and returned to the Lake. The story might be read as a stark warning against domestic violence. But there is a more positive kind of sequel. The couple had three sons and the mother sometimes appeared to them, teaching them about the medicinal qualities of the plants to be found in the area. The boys grew up to become skilful physicians who then recorded their knowledge in writing, “for the benefit of mankind throughout all the ages”.

In a quiet and modest way, Hywel thinks of himself as the inheritor this tradition of herbal knowledge. He has begun planting herbal leys in preference to rye grass because, as he says, “if I can’t grow them, who should?” As a society, we are probably only just beginning to discover how much can be learnt from the herbal medicines of the past. In part this is because the awareness of such sophisticated knowledge and wisdom has been obscured by more dominant, often urban-centric narratives. While the Enlightenment represented a huge advance in knowledge in some areas of the British Isles, the historian David Gange has written of how it benefited the big cities of the British Isles but actually heralded an age of darkness for other areas of the archipelago. In Wales it contributed to the suppression of the histories of the Age of the Saints, a period of intense Christian activity linked with learning and with the emergence of a deeply rooted Welsh culture.

Hywel takes inspiration from this ancient past as well as trying to draw on the practices of his own more recent ancestors. In some respects, regenerative farming means remembering agricultural methods from before the industrialisation of farming – which took place most significantly in the wake of the Second World War and the Agriculture Act of 1947. Farmers involved in nature-friendly farming often look back not to their fathers’ generation for wisdom but to that of their grandfathers and great-grandfathers, who were farming before the intensification of agriculture really took hold. In some ways, those generations modelled a way of life that seems preferable to the pressured lives of contemporary farmers. Hywel admits: “But hearing my father repeating stories about my grandad, his dad, I thought how fantastic life sounded. Hard, but just going up on a hill on horseback and chatting to a fellow grazier for hours and hours on end”. Now, in contrast, he says: “I feel like we’re just working. Like we’re running faster to stand still at the moment, because even at 15 I had my own sheep, and I pretty much had the same money then as I’m having now. It hasn’t changed. The price of fertiliser and feed and fuel and everything’s gone up crazy, but what we get for the end product hasn’t”.

The stories from the past, both ancient and more modern are significant. They speak of a tradition of farming on the Welsh uplands that has been in place for millennia. This tradition reflects a particularly deep relationship with the landscape built through hard toil and a commitment to learning the character of the land itself. Hywel’s story is an important counter to some of the current rewilding narratives that, at their most extreme, seem to suggest that the uplands would be better left untouched by farming of any kind. It is because of his careful stewardship that his land is flourishing.

Part of this process involves learning to see how the landscape might begin to heal itself. In a sense, Hywel is continuing in the tradition of the Physicians of Myddfai. Farmers like him are physicians of the land: wise practitioners who don’t impose a range of chemically based industrial-style remedies on the earth, but as the medieval Physicans of Myddfai were reputed to do, find ways of helping the patient through small interventions. This means moving away from the big-ag big pharma model in which agriculture is dominated by pharmaceutical companies and their agrochemicals, and thinking about what the land itself can do.

But regenerative farming does not just mean looking back in time. What struck me most when I first visited Esgairllaethdy was the way in which the wisdom of the past was being combined with some extraordinary contemporary technology. The Highland cattle on the hill wear collars fitted with GPS equipment. The collars enable Hywel to monitor where the cattle are and control their movement by setting up virtual fences using an app on his phone. When the cattle cross the boundary of the virtual field that Hywel maps out for them, the collars emit a high-pitched sound that causes them to step back into their allocated area. He tells me: “I think, in time, I’ll be able to manage without the collars, because the cattle will get used to the place”.

While Lyn y Fan Fach, the lake from which the legendary Lady emerged is two miles from Hywel’s farm, up on the mountain that adjoins his land, Hywel does now have a mini-lake of his own. He had always wanted a pond on his farm and two year’s into his membership of Glastir Advanced (a whole-farm sustainable land management scheme), he decided to build one. While some construction issues meant that the pond sometimes dries out, when the rain comes it creates a pool. After four days of heavy rain last Autumn, Hywel says, “the pond was full to overflowing”. He has witnessed how the pond has brought new species to the farm: “There was a duck there yesterday, there’s a heron, there’ll be Canadian geese, there’s all sorts of insects, dragonflies, around there”.

When I first visited Esgairllaethy in October 2021, I was at a low ebb: like everyone else, I was reeling from the practical and emotional effects of eighteen months of the pandemic, and from environmental fears prompted by the findings of the 2021 IPCC report and the figures for bioversity decline that came out before COP2021. But walking in the drizzling rain on the Open Farm Day walk, I felt buoyed up by an unexpected sense of hope. Here we were, in the midst of a vibrant landscape nurtured by a farmer whose deep love for the place and growing knowledge of its needs inform his farming practices. Species declining elsewhere are still present here and increasing in number – the hare, the curlew, and the skylark – and species new to the farm are arriving. With a newfound optimism, I thought of how the pond is providing a haven for passing waterfowl; how the Highland cattle on the hill are disturbing the ground, making new habitats for invertebrates and encouraging the growth of rare plants; and how the restored hedges are providing shelter for overwintering birds and shade for the livestock in summer. There’s a strong sense here of how the land is gradually recovering its health and how we in turn might heal our relationship with it.

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Pippa Marland

Excerpts from the interview with Hywel Morgan are quoted here with his kind consent.

This blog is written by Pen and Plough researcher Dr Pippa Marland and is based on her interview with Hywel Morgan (https://thepenandtheplough.wordpress.com/2022/05/17/an-interview-with-nature-friendly-farmer-hywel-morgan-pippa-marland/) and published with his permission. Illustrations by Katie Marland. This blog has been reposted with kind permission from Pippa Marland. View the original blog.

Katie Marland is an artist and illustrator based between Bristol and London, where she recently completed her masters at the Royal Drawing School. Her practice is research-led, working from esoteric texts, medical history, museum collections and from close observation of the natural world. Her work can be found on her website, on instagram @kmarlandart, and on twitter @kmarlandart.

[i] Additional information about the stories of the Lady of Lake and the Physcians of Myddfai is drawn from Terry Breverton’s (2012) The Physicians of Myddfai: Cures and Remedies of the Mediaeval World (Carmarthenshire: Cambrian Books).

IPCC blog series – Working Group 2 – Impacts, Adaptation and Vulnerability

Posted on by janet.crompton

 

 

This blog is part of a series from the Cabot Institute for the Environment on the Intergovernmental Panel on Climate Change’s recent sixth Assessment report, with this post covering the output of Working Group 2 and the impacts of climate change on society and ecosystems. This article also features a chat with Prof Daniela Schmidt, a Professor at the School of Earth Sciences at the University of Bristol, and a Lead Author on the IPCC’s AR6 report. For links to the rest of the series, see the bottom of the post.

Welcome to the next post in this series on the IPCC sixth Assessment Report (AR6). Now that we’ve covered the background science to climate change, the next phase looks at the impacts on society, ecosystems, and the intricate fabric of everything in between – combining the science and aiding the transition of translating to policies that governments can implement to better the planet and mitigate the impacts.

This report is, in my opinion, the most alarming of the bunch – some scientists referring to this as the “bleakest warning yet”. Here are the key points:

The increased frequency of Extreme Weather and Temperature will have a cataclysmic impact – Everywhere will be affected

There is no inhabited region on earth that escapes the impacts of climate change. It’s estimated that over 3.3 billion people are living in areas highly vulnerable to climate change effects – largely extreme temperatures, leading to food insecurity and water shortages. Extreme weather events, such as tropical storms and flooding, are also set to increase in both frequency and severity.

As we’ve seen in recent years, wildfires have become more common (Australia and California making international news) and will continue to rise in frequency – wreaking devastation on communities and wildlife. This, along with the retreat of glaciers and polar ice caps, also results in a release of even more carbon to the atmosphere as the Earth’s natural carbon sinks continue to be dismantled. The ensuing feedback loop amplifies the warming, only serving to increase the severity of these events.

However, the impacts of climate change won’t be experienced uniformly across the planet…

The Impacts of Climate Change will not be experienced equally

This is one of the most important statements from all three Working Groups. It’s been well reported that sea level rise will be existentially cataclysmic for atoll island nations such as Kiribati and the Maldives, but there are other effects of climate change that will be unequally experienced. At the other end of the scale, Britain and other western European nations will see less drastic impacts, despite having some of the greatest contribution to the emissions at the root of the climate crisis. In summer, some parts of the globe are already becoming unliveable due to the extremely high temperatures. In India and Africa for example, where temperatures can exceed 40 degrees C, the number of deaths due to heat are increasing year on year. Poorer communities, especially those who work outdoors, are disproportionately affected as their occupation puts them at greater risk.

Some of the nations with the lowest development and therefore lowest contribution to climate change will experience the impacts more than some of the greatest contributors.

A Climate Crisis exacerbates other ongoing Crises

The effects of a climate crisis add an extra layer of complexity to all sorts of problems the world is already facing. Threats to food and water security because of climate change will increase pre-existing geopolitical tensions as resources become more and more scarce. Therefore, the likelihood of conflict and war increases – which in turn shift focus from fighting climate change. To some extent, we are seeing this already with the war in Ukraine, for example. In summary, climate change can increase severity of a crisis and limits the efficacy of response.

Impacts on ecosystems are already happening as well

Mass die-offs of species are well underway, particularly in oceanic ecosystems as sea temperatures rise and ocean acidification takes place. Deforestation and wildfires are destroying ecosystems.

When I spoke to Professor Daniela Schmidt, a lead author on the WGII report (more from her at the end of the article), she was quick to point out and stress the connections between nature and society, links often underestimated – “Negative impacts on nature will negatively impact people”. Nature, land-use, and conservation will be some of the key tools in helping mitigate the effects of climate change.

This is something to explore further with the next blog in this series on Working Group 3: Mitigation of Climate Change.

Insight from IPCC AR6 Lead Author Professor Daniela Schmidt 

Daniela Schmidt is a Professor of Palaeobiology, Cabot Institute member and a key author on the IPCC’s WG2 report.

How did you get involved with IPCC AR6 and Working Group II in particular?

“I was a lead author on the fifth assessment report, working on the ocean chapter. I have since worked on reports for the European Commission on food from the ocean. I volunteered for this cycle with the expectation of working with WGI but I was assigned work on WGII, which was challenging because it was way out of my comfort zone. Working on this report has changed the way I will conduct research in the future, and has taught me to be more open to the complexities of life”

What’s one key point you’d like to get across from the WGII report?

“The official key strapline from AR6 is that the evidence is clear, climate change is real and happening right now. It’s a rapidly closing window of opportunity to do something about it.”

“One of the main things I like to communicate is that if we don’t hit 1.5 degrees C targets, then 1.7 degrees C is still better than for 2 degrees C example. The point is that every increment matters and that we can’t give up if we miss targets. I think it’s important to tell people that if we are overshooting 1.5 degrees C, yes, there will be consequences, some of which are irreversible, but we can still come back.”

“I also try not just to talk about climate change. Much of the adaptation action for climate change incidentally will, in my view, help to make the world a better place – providing clean drinking water, clean energy, habitable homes and ensuring there is nature surrounding them”

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We recommend taking a look at the IPCC’s full reports and report summaries for yourself if you seek to further understand the evidence and reasoning behind their headline statements.

Going further, potential solutions and climate change mitigations will be covered in greater detail in our summary of WG3’s report titled “Mitigation of Climate Change”, will be the next blog in this series, featuring a chat with IPCC AR6 Lead Author Dr. Jo House and contributor Viola Heinrich.

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Andy Lyford

This blog was written by Cabot Communications Assistant Andy Lyford, an MScR Student studying Paleoclimates and Climate modelling on the Cabot Institute Master’s by Research in Global Environmental Challenges at the University of Bristol.

Eurofisch: hyper-mobility, cosmopolitanism and the European eel’s appeal

Posted on by janet.crompton

Unlike the Atlantic salmon, the snake-like European eel (Anguilla anguilla) is widely perceived as devoid of charisma. An epic reproductive journey is integral to the salmon’s appeal. But an equally spectacular migration, if in reverse, defines the European eel. The sea-dwelling salmon returns to its freshwater origins. The freshwater-inhabiting eel goes back to its oceanic birthplace. Natural distribution represents another key point of similarity and difference. The salmon spans the North Atlantic, its European breeding grounds confined to more northerly freshwaters. The European eel, with its broader temperature tolerance, populates a wider latitude. Its habitat ranges from southern Iceland and Russia’s Kola Peninsula to the southern Mediterranean – despite the name, North Africa’s rivers and lagoons contain this eel species – and, on the Atlantic coast, as far down as the Canaries. From west to east, they are distributed from the Azores to Georgia.

Figure 1: ‘Artisanal’ dipnet fishing for elvers from the bank of the River Severn at Wainlode, Gloucestershire, on a spring evening in 2017 (Image: Environment Agency. Reproduced by permission of the Sustainable Eel Group). 

The eel’s Europeanness is most vividly demonstrated by its genes. Whereas the salmon displays high genetic diversity and reproductively discrete local populations, European eels all belong to the same breeding population. This singular, panmictic identity is rooted in a shared birthplace: the West Central Atlantic’s Sargasso Sea is a melting pot where every eel of the opposite sex is a potential breeding partner. And the place the next generation calls home could be anywhere within the species’ European range. Lacking the salmon’s homing instinct, the offspring of eel parents that spent their adult lives in Norwegian and Tunisian waterbodies respectively might settle in Wales. Alternatively, this progeny could end up in Portuguese freshwaters, or wherever the currents carry the tiny larvae (leptocephali) during their up-to-three-year odyssey. The European eel is the only truly pan-European fish: a paragon of cosmopolitanism I call ‘Eurofisch’.

On reaching western Europe, leptocephali metamorphose into glass eels. Shoals of these transparent mini-eels – also known as elvers in the UK – start entering southern Europe’s estuaries in December. But in 2012, fisheries scientists reported that ‘recruitment’ had fallen by up to 95 per cent since 1970. An Extinction Rebellion event in Yeovil, Somerset, in the summer of 2019, underscored the species’ critically endangered status. Protestors dressed as eels participated in a ‘drown in’ and a ‘European eel’ addressed South Somerset District Council.

I’ve recently examined the reasons for this drastic decline; tracked the emergence of concern; considered the remedies; looked at trafficking in glass eels for East Asia’s ‘grow-out’ farms that a Plymouth University project has characterized as an ‘unnatural migration’; and reflected on the prospects of eel appeal spreading. Mobilising popular support for eels is more difficult than drumming up enthusiasm for mammals, either terrestrial and marine (for example, ‘T-shirt’ animals such as pandas, polar bears, whales and dolphins). Few who have seen the 1979 movie version of Günter Grass’ novel, The Tin Drum (1959), will forget the stomach-churning scene on the Baltic beach near Danzig (Gdansk) where a fisherman hauls in a horse’s head writhing with eels that he pulls from ears, nostrils and throat.

Figure 2: Elvers wriggling upstream at Bradford on Tone, Somerset Levels, UK in April 2014. (Image: Andrew Kerr. Reproduced by permission of the Sustainable Eel Group). 

What I’d like to convey here is the richness of Europe’s eel heritage and how Eurofisch illuminates what it means to be European. The silver eel (the final, Sargasso-ready life stage) has the highest calorific value of any European fish. A venerable and varied culture of consumption unites Europe, from Spain to Sweden and from Ireland to Italy. Since early Christianity, roast eel has been the dish customarily served at midnight on Christmas Eve in Rome and Naples. The epicentre of Italian eel gastronomy, though, is Comacchio. Since the 1300s, this town in the Po Delta has hosted a silver eel fishery based on lagoons stocked with glass eels entering from the Adriatic. Eels are skewered and roasted, marinated in barrels, then canned. La Donna del Fiume (1955) starred Sophia Loren as an impossibly glamorous worker in a Comacchio cannery that’s now a museum.

In the early 1900s, glass eels were swept up hyper-tidal estuaries such as the Severn, Loire, Gironde, Minho and Tagus in tremendous quantities: surpluses were fed to pigs, fertilised vegetable plots and made into glue. In France, glass eels were boiled and served cold (‘spaghetti with eyes’). Meanwhile, in Severn estuary villages, super-abundant elvers were fried in butter or bacon fat, scrambled with eggs, or boiled and pressed into gelatinous, fried cakes. In Victorian London’s East End, whose labouring population could not afford salmon or meat, itinerant vendors of stewed and jellied eel and the ‘eel and pie’ shop were odoriferous fixtures of the cityscape. Dutch traders were supplying London by 1400 and in the late 1600s schuyts – ships fitted with wells for live export – established a mooring near Billingsgate fish market. Squirming cargos arrived almost daily until the early 1900s; the last schuyt docked in 1938.

In Frampton-on-Severn, the Easter Monday elver eating competition was woven deeply into village life. Male contestants gobbled down a pound of fried elvers. A contest for women (only required to consume half a pound) was founded in 1973. With steeply declining numbers and sharply rising prices, the contest was cancelled in 1990. Revival followed in 2015 – with ersatz elvers known as gulas, produced in Spain’s Basque country. Dubbed ‘elvers’ locally, gulas consist of surimi, blocks of fish paste from Alaskan pollack and Pacific whiting.

In June 2019, the Sustainable Eel Group, a science-led, Europe-wide campaign organisation, marked its tenth anniversary with a two-day meeting at the Natural History Museum and a week-long eel celebration. A highlight was the arrival at ‘Dutch Mooring’ of a reconstructed schuyt, absent from London’s riverscape for over 80 years. My visit coincided with that of Pieter Hak, proprietor of the Noted Eel & Pie House, Leytonstone. Hak told the Dutch crew that his great grandfather, a schuyt captain, sent his youngest son to London to learn the eel pie business in the 1890s. After he met and married the daughter of an English eel and pie shop owner, they opened their own place in Bow in 1926. Hak gave the crew a copy of Stuart Freedman’s paean to this hallowed Cockney institution, The Englishman and the Eel (2017); Hak appears on the cover, grasping a live eel. (Note, however, that an Italian immigrant established London’s oldest surviving eel and pie shops in 1902.)

Two years after leaving the EU, this sort of fishy connection can help, in a small way, to conserve a sense of Britain’s Europeanness. Britain’s eels belong to a wider European family, biologically and culturally. Our migratory eel also has a resounding message in an age of mass trans-border movements, reminding us that where we call home is not always where we, or our parents, were born.

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This blog is written by Cabot Institute for the Environment member Peter Coates, an Emeritus Professor of Environmental History at the University of Bristol as part of a joint Migration, Mobility and the Environment blog series with Migration, Mobilities Bristol. Some of the material in this post appeared in ‘Protecting Eurofisch: An Environmental History of the European Eel and its Europeanness’ in Greening Europe: Environmental Protection in the Long Twentieth Century – A Handbook (2022). Peter wrote a book on Salmon (2006) in Reaktion’s ‘Animal’ series and is currently writing a squirrel history of the UK.

Migration, mobilities and the ecological context

Posted on by janet.crompton

In this special blog series, Migration Mobilities Bristol (MMB) and the Cabot Institute for the Environment bring together researchers from across the University of Bristol to explore connections between movement and the environment from a multi-disciplinary perspective. Their diverse approaches highlight the importance of developing frames that incorporate both migration and environment, and in so doing benefit our understandings of both. 

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Migration can make you happy. When I see the first swifts arrive in the spring, I stop in my tracks and smile broadly at all and everyone. I have to restrain myself from telling people walking down the street that ‘they’ are back. Swifts are one of the wonders of the world – they make Concorde look clunky, they hurtle down streets in towns screaming wildly at dusk seemingly just for the fun of it, and scientists have calculated that the distance they fly over their lifetime is equivalent to flying to the moon and back seven times!

Dahlia (Bishop of Llandaff). Image credit: Jane Memmott

Migratory species like swifts have two homes and they are generally well regarded in both places. It’s a bit more touch and go whether alien species are welcome or not, and highly context dependent. For example, we deliberately introduce species from all around the world into our gardens without qualm – looking out the window onto my front garden, I’ve got honey bush and pineapple lilies from South Africa, Dahlias from Mexico, a Hebe from New Zealand, devil’s tobacco from Chile and foxgloves from seed collected down the road! In contrast, my local nature reserves are doing their best to remove Rhododendron, Cotoneaster and Himalayan balsam.

Context really is key here. Thus, gardens are grown for colour, relaxation, fruit, vegetables, and art (and I consider gardening as much of an art as a science) and they are highly managed and artificial habitats. In fact, they are increasingly considered as outdoor rooms in the media, and no one worries what countries their botanical furniture is from. In contrast, nature reserves are usually more natural settings where we want to capture natural patterns and processes, so there is an expectation that the species present should be native. And there is good evidence that while most alien species are harmless, some species (approximately 1%) can be very damaging to the environment and the economy.

Honey bush leaves (Melianthus major). Image credit: Jane Memmott

Migration is about mobility, and mobility is a key part of the scientific process. Thus, universities are ecosystems which provide intellectual homes to academics from all over the world. My own department is home to scientists from Africa, Germany, Brazil, Switzerland, Brazil, Italy and China and those are just the people I’ve bumped into over the last few days. COVID has put a bit of a spanner in the works on the mobility front, but mobility is so key to business that academics have quickly found other ways to be mobile. For example, in my own research group, we have been running a large project in a remote part of Nepal entirely by Zoom for the last two years. But, by dint of the internet and some incredible UK staff and amazing project partners in Nepal, we have trained field staff in ten remote villages in the Himalayas to collect diet data for both bees and villagers, using protocols that would have been very new to them. The data is then uploaded by the field staff to the internet and arrives on the computers the other side of the world as if by magic.

Mobility is such a large part of a scientist’s life that when it goes wrong it can feel shocking. I’ve had two encounters with mobility of scientists being blocked, one involving myself, another a visiting scientist. Mine was, I suspect, a straightforward random immigration check, but it did leave me rather shaken. I was travelling to Canada for the first time and got taken out of the queue and then grilled for 30 minutes on the nature of my visit. I was giving a plenary talk at a conference and had fortunately remembered to print out my letter of invitation. Unfortunately, I hadn’t actually read it for six months and so I probably did sound a bit suspicious. They did eventually let me in and it was an excellent trip thereafter. The second time was when a restoration ecologist from Latin America, who was visiting my research group for six months, went to Spain with his family for a weekend and upon return his whole family was issued with deportation papers. There is something deeply shocking about seeing the hostile environment process in action, especially when mobility is simply part of normal academic interchange. After some high-level work by an international lawyer this too was fixed. Restoration ecology is much more of a long-term process, but the restoration of mobility was much faster in this instance, if a lot more stressful.

Swift (Apus apus). Image credit: Wikimedia Commons.

Migration and mobility are everyday events in the environment. They can be natural such as the return of swifts each year, or they can be assisted such as the reintroduction programmes for species that have become extinct in the UK. One of the biggest reintroduction success stories is the red kite, a bird that you are almost guaranteed to see now if you drive down the M4 motorway or look out of the train window from Didcot to London. These are big and very beautiful predatory birds – imagine a paprika coloured swallow with a 6ft wingspan! My last few Saturdays have been spent driving from Bristol to a hospital in Hampshire to visit a sick relative and one of the things that has made this less stressful is counting the red kites along the motorway. Last Saturday was a 12-kite day, my highest count yet.

To end, migration, mobility and the environment are inextricably linked. There is both natural and human assisted movement of species in the environment. Species can be both welcome and unwelcome depending on the context. It’s complicated, but it’s the everyday bread and butter of ecologists around the world. With alien plants bringing colour and bizazz to our gardens and swifts bringing happiness as they return to their second homes in the UK, there is a lot to like about migration and mobility in the environment.

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This blog is written by Cabot Institute for the Environment member, Jane Memmott, Professor of Community Ecology in the School of Biological Sciences, University of Bristol. Her research interests include pollination ecology, invasion ecology, biological control and restoration ecology. In each case she considers how ecological networks can be used as a tool to answer environmental questions.

Professor Jane Memmott

Climate Change 2022: Impacts, Adaptations and Vulnerability – an IPCC lead author report summary

Posted on by janet.crompton

Professor Daniela Schmidt, a lead author of the recently published IPCC (Intergovernmental Panel on Climate Change)  report, Working Group II: Impacts, Adaptations and Vulnerability, recently gave an internal presentation to University of Bristol staff to summarise the report’s findings.

Recent geo-political events have meant that this report has understandably been overlooked in comparison to its predecessor, however, at 3500 pages and being the product of analysis of 34,000 papers since 2014, it is certainly not light reading. This writing aims to pinpoint and amplify the key messages from Daniela’s summary of Working Group II: Impacts, Adaptations and Vulnerability, as the Working Group III: Mitigation of Climate Change report has been released this week.

Solutions

The key take home message, was that the report offers solutions, but they are needed now. Daniela explained that it is not all doom and gloom, and it is important for our survival not to take it that way. From the report itself, the key quote, which you have perhaps seen shared elsewhere, is

The science is clear. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a livable future. This report offers solutions to the world.

Nature

One of the key solutions proposed in the report is nature, both in terms of its conservation and restoration and that it offers promising solutions to many of the threats we face. For example, the potential of natural carbon sinks, coastal protection, water management and urban cooling systems has been repeatedly evidenced, as well as the importance of integrating nature and natural solutions into urban spaces.

The report stresses that humans are part of ecosystems, not separate from them, and nature is crucial to our survival because of the essential and irreplaceable ecosystem services it provides. Fragmented, polluted and overexploited ecosystems are much more vulnerable to climate change, therefore, the report stresses it is therefore important to take a coordinated approach, with their protection and restoration in mind.

Interconnection

As well as the interconnectedness of humans and nature, the report evidences previously unrealised interconnections of climate risks. Risks are becoming more complex and there are compound and cascading risks through systems. For example, in terms of food scarcity, we need to consider that heat stress will not only reduce crop yields, but also the well-being and productivity of farm workers, further exacerbating the situation. There is an increased recognition of the interconnections between people, regions, society, ecosystems, biodiversity. This means that climate change cannot be seen as an individual problem, but as one intrinsically linked with natural resource depletion, ecosystem destruction, and growing urbanisation and inequity across the world.

Equality

Another key focus of the report was the importance of but lack of global equality, which will continue to be exacerbated in the face of climate change. 3.3  – 3.6 billion live in hotspots of high vulnerability to climate change, due to high levels of poverty, limited access to water, sanitation and health services, climate sensitive livelihoods and lack of funding and accountability in government. I would like to point out, that in the vast majority of cases, it is these communities whose carbon contributions are the least, which in my opinion strongly evidences to the fact that climate change is a political problem as well as a scientific one.

Due to inequality being a big problem, the report places an emphasis on the importance of promoting equality in the solutions and with this the need to listen to marginalised voices. Daniela explained that of global climate funding, 80% goes to mitigation, or reduction of emissions, while only 20% goes to adaptation, which is likely to be what is most consequential to more vulnerable communities.

After lack of action on deals made at COP26, which scientists have already argued at best would not be sufficient to solve the problem, a continued lack of action following these urgent messages will be deeply concerning for the fate of the planet, and especially for its most vulnerable communities.

Watch Daniela’s presentation to University of Bristol staff.

 

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This blog is written by Cabot Institute for the Environment member Hilary McCarthy, University of Bristol.
Hilary McCarthy

 

Climate change: effect on forests could last millennia, ancient ruins suggest

Posted on by janet.crompton

 

Jonathan Lenoir, Author provided

Jonathan Lenoir, Université de Picardie Jules Verne (UPJV) and Tommaso Jucker, University of Bristol

Forests are home to 80% of land-based biodiversity, but these arks of life are under threat. The rising average global temperature is forcing tiny plants like sidebells wintergreen on the forest floor (known as the understory) to shift upslope in search of cooler climes. Forest plants can’t keep up with the speed at which the climate is changing – they lag behind.

The pace at which forests adapt to changing conditions is so slow that species living in forest understories today are probably responding to more ancient changes in their environment. For instance, the Mormal Forest floor in northern France is, in several places, covered by a carpet of quaking sedge. This long grass-like plant betrays the former settlements of German soldiers who used it to make straw mattresses during the first world war.

Changes in how people managed the land, sometimes dating back to the Middle Ages or even earlier, leave a lasting fingerprint on the biodiversity of forest understories. Knowing how long the presence of a given species can carry on the memory of past human activities can tell scientists how long climate change is likely to have an influence.

A forest carpeted with tall grass.
The wind whispering through Mormal’s sedge evokes the region’s wartime past.
Jonathan Lenoir, Author provided

Ecologists are turning to technologies such as lidar to rewind the wheel of time. Lidar works on the same principles as radar and sonar, using millions of laser pulses to analyse echoes and generate detailed 3D reconstructions of the surrounding environment. This is what driverless cars use to sense and navigate the world. Since the late 1990s, lidar has enabled amazing discoveries, such as the imprints of Mayan civilisation preserved beneath the canopy of tropical forest.

In a new paper, I, along with experts in ecology, history, archaeology and remote sensing, used lidar to trace human activity in the Compiègne Forest in northern France back to Roman times – much later than historical maps could ever do.

Illuminating ghosts from the past

Compared to farm fields, which are ceaselessly disturbed, forest floors tend to be well-preserved environments. As a result, the ground below the forest canopy may still bear the imprints of ancient human occupation.

Archaeologists know this pretty well and they increasingly rely on lidar technology as a prospecting tool. It allows them to virtually remove all the trees from aerial images and hunt artefacts hidden below treetops and fossilised under forest floors.

Using airborne lidar data acquired in 2014 over the Compiègne Forest in northern France, a team of archaeologists and historians found well-preserved Roman settlements, farm fields and roads. Long considered a remnant of prehistoric forest, the Compiègne was, in fact, a busy agricultural landscape 1,800 years ago.

A black-and-white aerial photo of a landscape marked by depressions and boundaries.
Lidar can reveal the terrain hidden beneath forests.
Jonathan Lenoir, Author provided

A closer look at these ghostly images of the Compiègne Forest reveals several depressions within a fossilised network of Roman farm fields. Archaeologists excavated numerous depressions like this across many forests in north-eastern France and found that people from the late iron age and Roman era carved them.

These depressions were made to extract marls (lime-rich mud) to enrich farm fields in carbonate minerals for growing crops and to create local depressions where rainwater collects naturally for livestock to drink. Marling is still a widespread practice in crop production in northern France.

A hillside with a large, white crater in.
A pit for extracting marl in Northern France.
Jonathan Lenoir, Author provided

The long-lasting effects of human activity

These signs of Roman occupation in modern forests provide clues to why some plant species are present where we wouldn’t expect them to be.

On a summer day in 2007 in a corner of the Tronçais Forest in central France, a team of botanists found a little patch of nitrogen-loving species – blue bugle, woodland figwort and stinging nettle – nestled among more acid-loving plants.

Nothing special at first sight. Until archaeologists found that Roman farm buildings had once stood in that spot, with cattle manure probably enriching the soil in phosphorous and nitrogen.

A shrub with bright blue flowers.
Blue bugle heralds an ancient Roman farm.
Kateryna Pavliuk/Shutterstock

If a clutch of tiny plants can betray ancient farming practices dating back centuries or millennia, ongoing environmental changes, such as climate change, will have similarly long-lasting effects. Even if the Earth stopped heating, the biodiversity of its forests would continue changing in response to the warming signal, in a delayed manner, through the establishment of more and more warm-loving species for several centuries into the future.

Just as the Intergovernmental Panel on Climate Change has a mission to provide plausible scenarios on future climate change, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services aims to provide plausible scenarios on the fate of biodiversity. Yet none of the biodiversity models so far incorporate this lag effect. This means that model predictions are more prone to errors in forecasting the fate of biodiversity under future climate change.

Knowing about the past of modern forests can help decode their present state and model their future biodiversity. Now lidar technology is there to help ecologists travel back in time and explore the forest past. Improving the accuracy of predictions from biodiversity models by incorporating lagging dynamics is a big challenge, but it is a necessary endeavour for more effective conservation strategies.

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This blog is written by Jonathan Lenoir, Senior Researcher in Ecology & Biostatistics (CNRS), Université de Picardie Jules Verne (UPJV) and Cabot Institute for the Environment member Dr Tommaso Jucker, Research Fellow and Lecturer, School of Biological Sciences, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How ancient plants ‘learnt’ to use water when they moved on to land – new research

Posted on by janet.crompton
Focal point/Shutterstock

“Plants, whether they are enormous, or microscopic, are the basis of all life including ourselves.” This was David Attenborough’s introduction to The Green Planet, the latest BBC natural history series.

Over the last 500 million years, plants have become interwoven into every aspect of our lives. Plants support all other life on Earth today. They provide the oxygen people breathe, as well as cleaning the air and cooling the Earth’s temperature. But without water, plants would not survive. Originally found in aquatic environments, there are estimated to be around 500,000 land plant species that emerged from a single ancestor that floated through the water.

In our recent paper, published in New Phytologist, we investigate, at the genetic level, how plants have learnt to use and manipulate water – from the first tiny moss-like plants to live on land in the Cambrian period (around 500 million years ago) through to the giant trees forming complex forest ecosystems of today.

How plants evolved

By comparing more than 500 genomes (an organism’s DNA), our results show that different parts of plant anatomies involved in the transport of water – pores (stomata), vascular tissue, roots – were linked to different methods of gene evolution. This is important because it tells us how and why plants have evolved at distinct moments in their history.

Plants’ relationship with water has changed dramatically over the last 500 million years. Ancestors of land plants had a very limited ability to regulate water but descendants of land plants have adapted to live in drier environments. When plants first colonised land, they needed a new way to access nutrients and water without being immersed in it. The next challenge was to increase in size and stature. Eventually, plants evolved to live in arid environments such as deserts. The evolution of these genes was crucial for enabling plants to survive, but how did they help plants first adapt and then thrive on land?

Stomata, the minute pores in the surface of leaves and stems, open to allow the uptake of carbon dioxide and close to minimise water loss. Our study found that the genes involved in the development of stomata were in the first land plants. This indicates that the first land plants had the genetic tools to build stomata, a key adaptation for life on land.

The speed in which stomata respond varies between species. For example, the stomata of a daisy close more quickly than those of a fern. Our study suggests that the stomata of the first land plants did close but this ability speeded up over time thanks to gene duplication as species reproduced. Gene duplication leads to two copies of a gene, allowing one of these to carry out its original function and the other to evolve a new function. With these new genes, the stomata of plants that grow from seeds (rather reproducing via spores) were able to close and open faster, enabling them to be more adaptable to environmental conditions.

Images of a plant's stomata, open and closed.
Shutterstock

Old genes and new tricks

Vascular tissue is a plant’s plumbing system, enabling it to transport water internally and grow in size and stature. If you have ever seen the rings of a chopped tree, this is the remnants of the growth of vascular tissue.

We found that rather than evolving by new genes, vascular tissue emerged through a process of genetic tinkering. Here, old genes were repurposed to gain new functions. This shows that evolution does not always occur with new genes but that old genes can learn new tricks.

Before the move to land, plants were found in freshwater and marine habitats, such as the algal group Spirogyra. They floated and absorbed the water around them. The evolution of roots enabled plants to access water from deeper in the soil as well as providing anchorage. We found that a few key new genes emerged in the ancestor of plants that live on land and plants with seeds, corresponding to the development of root hairs and roots. This shows the importance of a complex rooting system, allowing ancient plants to access previously unavailable water.

A dam floor cracked by lack of water.
Hot weather and climate changes left this Bulgarian dam almost empty in 2021.
Minko Peev/Shutterstock

The development of these features at every major step in the history of plants highlights the importance of water as a driver of plant evolution. Our analyses shed new light on the genetic basis of the greening of the planet, highlighting the different methods of gene evolution in the diversification of the plant kingdom.

Planting for the future

As well as helping us make sense of the past, this work is important for the future. By understanding how plants have evolved, we can begin to understand the limiting factors for their growth. If researchers can identify the function of these key genes, they can begin to improve water use and drought resilience in crop species. This has particular importance for food security.

Plants may also hold the key to solving some of the most pressing questions facing humanity, such as reducing our reliance on chemical fertilisers, improving the sustainability of our food and reducing our greenhouse gas emissions.

By identifying the mechanisms controlling plant growth, researchers can begin to develop more resilient, efficient crop species. These crops would require less space, water and nutrients and would be more sustainable and reliable. With nature in decline, it is vital to find ways to live more harmoniously in our green planet.The Conversation

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This blog has been written by Alexander Bowles, research associate, University of Bristol.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Alexander Bowles

 

 

Urban gardens are crucial food sources for pollinators – here’s what to plant for every season

Posted on by janet.crompton
A bumblebee visits a blooming honeysuckle plant.
Sidorova Mariya | Shutterstock

Pollinators are struggling to survive in the countryside, where flower-rich meadows, hedges and fields have been replaced by green monocultures, the result of modern industrialised farming. Yet an unlikely refuge could come in the form of city gardens.

Research has shown how the havens that urban gardeners create provide plentiful nectar, the energy-rich sugar solution that pollinators harvest from flowers to keep themselves flying.

In a city, flying insects like bees, butterflies and hoverflies, can flit from one garden to the next and by doing so ensure they find food whenever they need it.
These urban gardens produce some 85% of the nectar found in a city. Countryside nectar supplies, by contrast, have declined by one-third in Britain since the 1930s.

Our new research has found that this urban food supply for pollinators is also more diverse and continuous throughout the year than in farmland. Everyone with a garden, allotment or even a window box can create their own haven for pollinators. Here are tips on what to plant for each season.

Three people in wellington boots work on raised beds in a garden.
Community gardens, allotments, even window boxes can sustain pollinators throughout the year.
KOTOIMAGES | Shutterstock

What to plant in spring

The first queen bumblebees emerge from winter hibernation in February and March. They need food straight away.

At this time of year nectar-rich plants are vital energy sources for warming up cold flight muscles, with pollen providing the necessary protein for egg laying and larval growth. In early spring much of the countryside is still bleak and inhospitable.

Gardeners can help by planting borders of hellebore, Pulmonaria and grape hyacinth. Trees and shrubs such as willow, cherry and flowering currant are also fantastic for packing a lot of food into a small space.

A bee on a willow flower
Willow in bloom.
Ira Kalinicheva | Shutterstock

What to plant in summer

In late spring and early summer, pollinators have more food available – but there is also more competition for it. So it is crucial to ensure you have a diverse array of different flowering plants. This will guarantee there is attractive and accessible food to suit a wide range of insects and provide them with nutritionally balanced diets.

A great assortment of plants, including honeysuckle, Campanula and lavender, can provide floral resources in summer. Mowing the lawn a little less often will help too, giving the chance for important so-called weeds, such as clover and dandelion, to bloom.

Ivy in bloom with a red admiral.
Ivy in bloom with a red admiral.
Seepix | Shutterstock

What to plant in autumn

By late summer and autumn there are fewer species still flowering in gardens. A handful dominate the nectar supplies, particularly Fuchsia, Salvia and Crocosmia.

For many pollinators, however, these flowers are entirely useless. Their nectar is hidden away down a tube, only accessible to insects with long tongues, such as the garden bumblebee.

This means solitary bees and hoverflies may need to find other sources of food. The gardener can help by prioritising open and accessible flowers. Opt for species such as ivy, Sedum, Echinacea and oregano.

What to plant in winter

Few pollinators are still active in winter. Most species die off leaving the next generation behind as eggs, larvae or pupae.

But bumblebees and honeybees remain in flight, taking advantage of the warmer climate and winter flowers that cities can provide. By vibrating their wings, bumblebees can warm up to forage in temperatures barely exceeding freezing point, but they need a lot of energy-rich nectar to do so. If you want to attract bees into your garden during the winter some of the best options are Mahonia, sweet box, winter honeysuckle and the strawberry tree.

Yellow Mahonia on a frosty morning.
Mahonia on a frosty morning.
Sally Wallis | Shutterstock

Urban gardens are small and numerous, with hundreds or even thousands packed into a single square kilometre of a residential neighbourhood. Each gardener is different, with individual preferences of what to plant, how regularly to mow the lawn and even how to decide what constitutes a weed.

This results in an enormous variation from garden to garden in the quantity of nectar, the timing of its production and the types of flowers producing it. But there is always room for improvement. Some gardens provide pollinators with hundreds of times less nectar than others.

So keep yours well stocked with nectar and free from toxic pesticides. You’ll be amazed by the impact you can have.

This blog is written by Caboteers Nicholas Tew, PhD Candidate in Community Ecology, University of Bristol; Jane Memmott, Professor of Ecology, University of Bristol, and Katherine Baldock, Senior Lecturer in Ecology, Northumbria University, Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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