Across
the globe, vast swathes of land are being left to be reclaimed by
nature. To see what could be coming, look to Bulgaria.
Abandonment,
when it came, crept in from the outskirts. Homes at the edge of town
were first to go, then the peripheral grocery stores. It moved
inward, slow but inexorable. The petrol station closed, and creeper
vines climbed the pumps, amassing on the roof until it buckled under
the strain. It swallowed the outer bus shelters, the pharmacies, the
cinema, the cafe. The school shut down.
Today,
one of the last institutions sustaining human occupation in Tyurkmen,
a village in central Bulgaria, is the post office. Dimitrinka
Dimcheva, a 56-year-old post officer, still keeps it open two days a
week, bringing in packages of goods that local shops no longer exist
to sell. Once a thriving town of more than 1,200, Tyurkmen is now
home to fewer than 200 people.
On
a warm spring afternoon, Dimcheva stood in the town square. “The
weddings took place here, all of the folk dances, the volleyball.
There were lots of young people. A pool,” she said. She gazed
around, pointing to ruins or now-empty spaces where buildings once
stood, remembering. There, the building that housed a small cinema.
Behind it, the space for a school that burned down, was rebuilt, then
closed. “Life was bubbling.” Now, she said, “life in the
villages is dying”.
Thousands
of similar villages are scattered across Bulgaria. After the fall of
communism, people flocked to the cities in search of work, and over
the next 30 years many villages emptied to the point of obliteration.
As of the 2021 census, almost 300 villages were completely abandoned,
and more than 1,000 had populations below 30 – most of them very
elderly. With its low birthrates and high rates of emigration,
Bulgaria has been emptying out for decades. Its population has
dropped from close to 9 million in 1989, to fewer than 6.5 million – one of the worst peacetime population declines in modern history.
Bulgaria
lies at the extreme end of this kind of demographic change, but the
forces reshaping it are acting everywhere. Over the past half
century, the global portion of people living in rural areas has
decreased by almost a third. Farming is becoming increasingly
industrial and concentrated. More than half of all people now live in and around cities, and that figure is
expected to rise to 70% by 2050. In many countries, birthrates are
dropping steadily, and while the global population is projected to
keep growing until 2080, around half of that growth is being driven by fewer than 10 countries.
As
populations move and shrink, people are leaving long-occupied places
behind. Often they leave everything in place, ready for a return that
never comes. In Tyurkmen, Christmas baubles still hang from the
curtain rails in empty houses, slowly being wrapped by spiders. In
one abandoned home, a porcelain cabinet lay inside a crater of rotted
floorboards, plates still stacked above a spare packet of nappies for
a visiting grandchild. Occasionally, abandonment happens all at once,
when a legal ruling or evacuation sends people scuttling. But mostly,
it is haphazard, creeping, unplanned. People just go.
Since
the 1950s, some scholars estimate up to 400m hectares – an area close to the size of the European
Union – of abandoned land have accumulated across the world. A team
of scientists recently calculated that roughly 30m hectares of farmland had been
abandoned across the mainland US since the 1980s. As the climate
crisis renders more places unliveable – too threatened by flooding,
water shortages and wildfires to build houses, soil too degraded and
drought-stripped to farm – we can expect further displacements.
This
world-altering shift has drawn remarkably little attention. “It has
been there all the time – but we did not really describe it,”
says Prof He Yin of Kent State University, one of the scientists now
using remote sensing to create global maps of abandoned land. “We
talk about expansion,” he said, referring to development of land.
“Yes, absolutely that’s important. But there’s this other side
– abandonment – that people don’t really talk about.”
Alongside
this story of depopulation is another story – of what happens to
the land left behind. To preserve a livable planet, it is crucial to
preserve and expand forests, grasslands, healthy ecosystems and wild
places. Huge expanses of abandoned land represent an opportunity but
also a question, an ongoing experiment without clearly predictable
outcomes. For thousands of years, humans have dramatically shaped the
places where they live, transforming the Earth’s face. So what
happens to the natural world when people disappear?
It
was this puzzle that drew ecologist Gergana Daskalova to Tyurkmen. On
a hot, quiet morning in May she walked down the main street. It was
empty of people, but lined by papers that fluttered in the early
summer heat, tugging at their staples on the fences, gates and power
poles. When a member of the household dies in Bulgaria, it is
traditional to mark their passing with a notice. The A4 printouts
featured a name, photograph, date of death and a brief tribute. Each
noted how long ago the loved one had died: six months, a year, a
decade, 22 years. In villages across the country, these posters often
also mark the end of human habitation. “If you walk around, you’ll
see it’s like this clock that’s ticking, measuring the time since
those people have left us,” Daskalova said. “On a human level,
that’s very sad. But that clock, it’s also measuring the end of
human impact, and the onset of environmental change afterwards.”
Daskalova
specialises in global change ecology: how large-scale human activity
is reshaping the natural world. She is in the middle of an ambitious
research project, studying 30 villages across the Bulgarian
countryside in different stages of abandonment. Along with
collaborators and students, she is gathering a huge range of data:
using aerial drones to map the return of forests, block-by-block
botany surveys to see what plants are growing, audio recorders on
trees to capture shifts in the density and volume of birdsong. Over
time, she hopes to compare the ecology of derelict villages with
those where some people remain, providing a comprehensive picture of
how nature responds when humans leave.
Daskalova,
is in her early 30s, with a chatty warmth and patient knack for
breaking down scientific theory, possibly honed by a year of
explaining to curious shepherds why she’s out strapping microphones
to trees in remote fields. She recently gave birth to her son, and on
some days he watched from her hip, swaying and serious-eyed, as she
strode around research plots.
Tyurkmen
was not a randomly selected research site – it is the place she
grew up. Like many of her generation, as a young child Daskalova was
largely raised by grandparents while her parents went to work in the
nearest city. Eventually, she left for university. “For a decade, I
was one of the people who left the village and only returned
occasionally, and every time I came back, there were less and less
people living on my street,” she said. When she was younger,
Daskalova would track the creep of abandonment in the wintertime,
watching to see whether smoke emerged from a chimney down the street,
or light shone from one of the windows. “Instead, one by one, the
lights get turned off,” she said.
For
the first few years of her career, Daskalova worked in far-flung
places, including the arctic tundra. But she remembered the great
depopulation she had lived through, and recognised that it was part
of something wider, with scope to reshape the future of thousands of
species.
Today,
she lives and works in the home in Tyurkmen that once belonged to her
grandparents. All around her, homes stand empty. Across the street,
one house has crumpled inward, like a cardboard box left in the rain.
Inside, that morning, nesting barn swallows orbited a bedroom. The
front door had been knocked off its hinges, still carrying an enamel
plaque: an award dispensed by communist-era local authorities,
reading “exemplary home”.
Abandoned
places are not the most alluring research sites: “They’re not the
rainforests, not the gorillas,” said Daskalova. Individually, each
research site is just a village, like thousands of others. “But in
a way that’s what makes it special,” she continued, “because
depopulation is happening at a really big scale.” And what comes
after abandonment is often not what we expect.
News
that great swathes of our planet are being abandoned can excite
visions of a rewilded Eden in the ruins of humanity. In the absence
of humans, nature will come roaring back. Deer will roam the streets
of crumbling cities, vines will crack the concrete, football fields
will give way to forests. The skies will clear and species will
flourish. In 2020, lockdowns gave many people a taste of what
semi-abandonment might look like. As humans were forced indoors, wild
creatures returned to some urban streets and suburban gardens.
“Humans are the virus,” observers declared, in a mixture of
earnest commentary and internet punchlines. In their absence, “nature
is healing”.
Visions
of humans as a pox upon the natural world – and of paradise
sprouting in our absence – are intertwined with some of ecology’s
oldest ideas. In the late 19th century, botanist Frederick Clements
helped popularise succession theory, the idea that left to its own
devices, any disturbed landscape will follow a step-by-step
progression. A ploughed field, for instance, will be overtaken first
by fast-growing grasses and weeds, then shrubs, which finally thicken
into trees and forest. Clements argued that any place would move
through succession to a “climax” state of stable equilibrium. The
final result could differ according to climate and geography, an
alpine forest being different from a swamp or desert. But the
essential trajectory was always the same: a “universal law”,
Clements wrote, of ecosystems climbing toward climax like an animal
progressing through infancy toward adulthood.
The
idea gained traction through the early 20th century, coinciding with
a period of explosive growth in human cities, populations and
industry. It had a kind of simple, elegant beauty. As people watched
human activity transform the earth around them, it also offered a
certain comfort. No matter how dramatic the disturbance – whether
the retreat of a glacier or the razing of a forest for farmland –
nature’s capacity to return remained. That ideal climax state would
rest like a substrate beneath the soil, lying dormant even as the
land above was tilled or excavated or burned or paved. To return, all
it needed was time and benign neglect.
Over
time, Clements’ more sweeping theories were picked apart by fellow
botanists. The stable, permanent climax communities he had theorised
proved elusive: field studies continued to find ecosystems passing
through unpredictable cycles of collapse, regeneration, divergence
and stasis. Today, this deterministic version of succession theory is
seen as widely debunked. But Clements’ vision endured in the
popular imagination – sometimes to the frustration of ecologists.
“Many popular ideas about the environment are premised on the
conviction that nature is … capable of preserving its natural
balance more or less indefinitely if only humans can avoid disturbing
it,” ecological historian William Cronon wrote in 1995. “These
stories are ours, not nature’s. The natural world does not organise
itself into parables.”
In
practice, scientists have found that humanity’s relationship to the
natural world is far more complex than we often assume. This is one
of Daskalova’s more counterintuitive findings: rather than always
being antithetical to nature, human presence can help make life
possible for a vast array of species. Even more surprisingly, total
abandonment can sometimes have worse consequences for biodiversity
than landscapes where some people remain.
To
show how this could be possible, Daskalova drove me to a village
buried in vines. Kreslyuvtsi lies in semi-mountainous regions of
central Bulgaria. For years now, most of the village has been
completely abandoned. In the spectrum of villages that Daskalova is
studying, it offers a case study of what something approaching
absolute human absence brings.
Standing
at the edge of a hillside, Daskalova gingerly took a step off the
path and out into space. When her foot landed, she bounced ever so
slightly, held up by the latticing of thousands of bramble vines,
woven tightly enough to create their own buoyant elasticity.
Somewhere beneath was a steeply sloped bank of land, and out a few
metres in front was one of the long-abandoned homes of Kreslyuvtsi
village. Its form was slowly collapsing as the stone walls crumbled.
Brambles had surged up over the house until only an upper corner of
the tiled roof was fully visible, jutting above the vines like the
prow of a boat in its final stages of sinking. “They will swallow
this place whole,” Daskalova said.
The
brambles illustrate the first force that abandoned land faces: when
humans leave en masse, new dominant species can make a clean sweep.
The worst offenders are not brambles, but imported, invasive species.
In Poland, where about 12% of farmland was abandoned after the fall
of communism, the fields have turned thick mustard yellow, blanketed
by the bright pollen cascades of Canadian goldenrod. This species has
colonised about 75% of the country’s abandoned fields, and where
goldenrod grows, little else thrives. Scientists studying this
abandoned land found that wild pollinators decreased by 60% - 70%, and the number of birds halved. In Bulgaria, an
emerging threat is the Tree of Heaven (Ailanthus
altissima),
a hardy, fast-growing, disease-resistant tree from northern China,
with bitter-smelling sap that repels other plant, animal and
microbial life.
These
monocultures can create “biological deserts”, where just one
species grows. The need to diversify them is not only an aesthetic,
human preference. Monocultures are associated with soil degradation
and nutrient depletion, extinctions of other species, difficulty
purifying water, catastrophic wildfires, vulnerability to drought and
the rapid spread of disease.
In
some cases, a monoculture’s dominance is temporary. Even virulent
invasive species can sometimes act as “nursery” environments for
a variety of plants and creatures that might eventually outgrow them.
Other times, an ecosystem may stall, failing to recover or diversify.
“It is widely believed that once destroyed, forests can recover
naturally from grassland or shrubland within a few decades in a
process known as forest succession, and that tree planting can help,”
scientists discussing the process on Hong Kong plantations wrote in 2023. “Our study
shows that forests do not recover as much, or as rapidly, as people
think they do.”
Humans
are often responsible for creating monocultures. But there is also a
surprising, unacknowledged role that people can play in holding them
back.
Out
among the brambles in Kreslyuvtsi, Daskalova turned, carefully
dragging her gumboots back toward the path winding up the hillside.
Reaching the path, she crouched in the grass and began to name
species around her feet: grasses, ivy, but also buttercups, purple
flowering vines, a tiny yellow orchid. “I can’t imagine many
people walk up this road, but every once in a while some do,” she
says. In the process, they have held back the rising tide of
brambles, and opened up space for this small flurry of species, a
scatter of colour against the flat green opacity of vines.
From
where Daskalova stood, the path led up to an opening in the trees,
where long grass and wildflowers grew in a clearcut meadow. Here,
again, a small island of fragile blooms revealed the history of this
land. Buttercups and agricultural weeds signalled that humans were
here in the not-too-distant past, as did the clearing itself.
Daskalova pointed to the thick-woven darkness of trees around the
space, arranged like an audience in an amphitheatre, their network of
branches already forking into the precious light of the clearing.
“They’re right at the edge, ready to move in when that
opportunity arises,” she said. “If there’s no grazing or
mowing, it could only be something like five years until it’s all
in the shadows of a denser canopy.”
When
people imagine ecosystems recovering, this return to forest is often
what springs to mind. But forests only represent a small sliver of
possible habitats. For other species, the currency of life is light,
and a dense, closed canopy of forest is impossible to survive. A
swallow is perfectly adapted to vast, open fields: the curve of its
wings and distinctive forking tail designed for fast pursuit of
insects hovering above meadows. A starling murmuration, moving across
the sky like spilled pepper over a tablecloth, is an adaptation to
open fields: repelling predators, protecting the roost. Vast numbers
of species adapted and co-evolved with these open places – plants,
mammals, insects, grazers, species like wildflowers, that relish
disturbance and light. The rich biodiversity of open grasslands can
be even greater than that of temperate forests.
Once,
many of these kinds of environments were created by megafauna.
Mammoths, giant water buffalo, bison and cave bears were large enough
to reshape forests, toppling trees to create steppes and prairie.
Scientists have estimated that megafauna were responsible for keeping about 30% of South America’s forests at bay. Almost all of them are
now extinct, the timing of their demise usually linked to the arrival of humans. In many places, humans are the
only remaining creatures that can consistently reshape landscapes in
these radical ways, pushing back the shade of the trees for other
creatures to take root.
For
millennia, all across the planet, humans have been using fire and
tools to open up land for agriculture, gardens, grazing and hunting.
In the process, we created ecological “mosaics”, or “patchworks”:
landscapes that hold a mixture of habitats, like meadows, gardens and
forests. These places were not designed as nature reserves, but they
often catered to hugely diverse animal life. In her book Nature’s
Ghosts, Sophie Yeo details research indicating that European hay meadows cultivated for
animal feed were actually more successful at preserving a vast array
of species than meadows explicitly cultivated for biodiversity.
Looking back over the early Holocene – beginning 11,700 years ago –
researchers have found that human presence was about as likely to increase biodiversity as reduce it.
Not
all human-created landscapes have the same value. A paved subdivision
with astroturfed lawns is very different to a village with diverse
vegetable and flower gardens. A traditional hay meadow is radically
different from a pesticide-drenched plantation of soya beans. But
scientists continue to find evidence that the old idea of humans as
antithetical to nature is also wrong-headed, and that rosy visions of
thriving, human-free environments are more imaginary than real.
“People are still imagining [nature as] this kind of pristine place
that’s going to be saved from people,” says US environmental
scientist Erle Ellis. “That is definitely a misunderstanding.”
In
2021, Ellis published new research that looked back 12,000 years. He
and his colleagues found that nearly three-quarters of Earth’s land
was occupied and shaped by human societies. Other researchers have
pushed even further back. Examining human-biodiversity interactions
in the Late Pleistocene – back as far as 120,000 years –
scientists concluded that across most of the planet, “‘Pristine’
landscapes simply do not exist and, in most cases, have not existed
for millennia”.
Many
of the landscapes people now tend to think of as untouched, from the
savanna lands of equatorial Africa to the deep Amazon rainforest,
have already been deeply transformed by human presence. “The
essential role that people play in ecology is the critical thing, and
it’s been ignored,” Ellis says. “The most biodiverse places
left on Earth – this is almost universally true – have Indigenous
people in them. Why? Well, they conserve a lot of that biodiversity
and actually produce it. They maintain that heterogeneous landscape.”
There
is no question that recent human activity – particularly the
massive clearing of ecosystems and industrial consumption of fossil
fuels – has been an ecological catastrophe. But for nature to be
restored to a past version of itself, the question might be less one
of human absence, than what form human presence can take.
In
the small communities riding out abandonment in Bulgaria, you
sometimes see patches of gentle human presence that might offer paths
for the future, as well as glimpses of the past. Off Tyurkmen’s
main street, a dirt road leads to a stretch of scrubby meadowland. On
the day I visited, Slavcho Petkov Stoyanov, who is 56 years old,
stood watching as his sheep grazed among the shrubs. “Years ago,
nobody would have let me graze here,” he said. “All this was used
for growing vegetables.” His is the last flock in the village and
he usually employs shepherds to watch them – but recently those
young men left town and he was back out in the fields himself,
sitting in a patch of shade to dodge the midday sun.
Stoyanov
is one of the few remaining people here who help to maintain a
diverse, “mosaic” landscape: in some empty blocks, the canopy of
trees is expanding, but others are cleared by grazing and littered
with wildflowers. He offers an example of how some forms of human
occupation can be a protection against environmental damage rather
than a source. As rural places like Tyurkmen depopulate, they become
vulnerable to new forms of exploitation: land prices drop, and there
are fewer people around to oppose projects like mines and quarries.
“What you can get is depopulation as a stepping stone to
industrialisation,” Daskalova told me.
Stoyanov
pointed to the reservoir below the fields. His grandparents helped
dig it themselves. Then, a few years ago, a company was granted cheap
contracts by the municipality to take fish from it. The process
followed a brutal, short-term logic: they installed pumps, drained
the reservoir, and scooped the fish out. Almost everything else died.
“They got about 20 tonnes of fish,” Stoyanov said. The remaining
villagers were furious, and mounted a successful campaign to have the
contract ended. The reservoir has slowly refilled, with water, fish,
birds. Over time, he hopes parts of the village will refill, too.
They have new opponents now, including a limestone quarry proposed at
the village boundary.
To
harness the full environmental possibilities offered by the great
abandonment will require changing our conception of humanity’s
relationship to nature, and understanding how our species can benefit
ecosystems as well as harm them. It will also require human
intention: neglect alone is not enough. Around Slavcho’s herds, the
backdrop of Tyurkmen was transforming. Patches of forest thrust
outward, vines demolished villas, chemical-smelling invasive thickets
occupied meadows. The march of nature seemed inexorable, but its
future was still uncertain, contingent on the remaining people: what
would they allow to grow? What would they keep at bay?
This
point about uncertainty recurs again and again in conversations with
scientists studying abandoned land. For biodiversity to thrive it
needs time. The same forces that drive people from a place –
pandemics, wars, shifting economic tides – can send them flowing
back. He Yin, working with a group of scholars, found that millions of hectares of abandoned land were recultivated
within a few decades. Their neglect was “too ephemeral” to
translate into true gains for nature.
At
one of Daskalova’s longest-abandoned monitoring sites, she had seen
the trees grow thick and steady, undisturbed since the last occupants
left. “Nobody had stepped on that plot in nearly half a century,”
she said. Then, this year, a new set of owners appeared. They had
plans for a guesthouse, transforming the isolated plot into a
sanctuary for holidaymakers. “The first thing they did was to clear
every single bit of vegetation – they just bulldozed the whole
thing,” she said. The forest was shorn back and ploughed into dirt,
the plot left dotted with a few invasive weeds.
After
clearing the land, the buyers realised their new project would not be
profitable. “They gave up on the guesthouse idea,” Daskalova
said. “Now it’s abandoned again.”
The
great abandonment: what happens to the natural world when people
disappear? By Tess McClure. The Guardian, November 28, 2024.
