Cemeteries Can Serve as Lifeboats That Protect Biodiversity
our white-tailed deer graze atop a rise, oblivious to Jay P Lee and GW Palen, and other folks named Stowell and Whitehead and Slayton and Potter interred there. It’s afternoon – an uncommon feeding time for deer that usually prefer dawn and dusk – on a fall day at Mount Hope Cemetery in Lansing, Michigan. The deer browse amongst the graves, apparently unperturbed by the writer, photographer, and ecologist walking at the foot of their hill, discussing varieties of lichen on tombstones, the food value of nonnative honeysuckle for wildlife, and the evils of invasive buckthorn.
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Whether urban or rural, cemetaries reflect the key ecological principle of “habitat islands” – patches of wildlife habitats surrounded by large areas of unsuitable habitat. (photo Bryan Burke)
The ecologist is Brian Klatt, director of the Michigan Natural Features Inventory, and we’re exploring the cemetery, which was farmland until 1873. It sits at the intersection of two busy roads about three miles from the classic white-domed state capitol and backs into the floodplain of Sycamore Creek. The best-known of those buried here is Ransom Olds, founder of the Oldsmobile company. While much of the 82 acres is mown and planted with nonnative grasses, the hilly terrain still contains high-quality remnants of native habitat. Snakes feed and overwinter in the floodplain but hunt on the sunnier higher ground, Klatt says. Owls and other birds shelter from winter storms in the white cedars. Maples produce huge amounts of seeds. Black oak produce acorns, or “mast,” a staple for squirrels, deer, and other urban wildlife. Klatt also points out an ash, that “disappearing guy,” a species beleaguered by the emerald ash borer that’s wiped out millions of trees in the Great Lakes Basin alone.
When it comes to protecting biodiversity, Klatt says, cemeteries provide “a lot of the same benefits you get from parks.” Whether urban or rural, they reflect the key ecological principle of “habitat islands” – patches of wildlife habitats surrounded by large areas of unsuitable habitat.
The scientific concept of habitat islands, or insular biogeography, was originally developed to explain species richness on actual islands but has since expanded to include the study of other isolated natural communities, including cemeteries. The concept is widely used as a basis for designing reserves and can be used to predict the number of species that call an ecosystem home. In some cases, the numbers are astounding. A study in an Illinois cemetery, for instance, found 28 prairie plant species in a single square meter. Of course, the diversity found in each of these “islands” depends on several variables, including their size, their distance to the next or nearest islands, and greenspace connections like river corridors and floodplains, such as the Sycamore Creek floodplain by Mount Hope.
Until recently, scientists in ecology-related disciplines have only sparingly studied cemeteries. Fortunately, that inattention is starting to change amid mounting concern about climate change, urban sprawl, habitat destruction, and species extinction on a local, regional, and global scale. The result is growing evidence of the value of cemeteries to biodiversity, whether it be to orchids, breeding birds, white-footed mice, or other little-known and rare plant and animal species.
I’ve explored burial grounds around the world for decades, not as a scientific researcher or environmental journalist but as a, well, graveyard tourist. The places I’ve visited range from crumbling Muslim cemeteries on arid heights overlooking Lake Issyk-Kul in Kyrgyzstan, to Alaska’s Russian Orthodox Eklutna Cemetery with its brightly painted “spirit houses,” to the hardwood-shaded Authors Ridge in Sleepy Hollow Cemetery in Concord, Massachusetts – where I stood over the burial site of the literary likes of Louisa May Alcott, Ralph Waldo Emerson, Nathaniel Hawthorne, and Henry David Thoreau. I’ve marveled at the manicured precision of Arlington National Cemetery, and maneuvered my way through old, crowded kirkyards with leaning grave markers in Scotland.
For me at first, they were islands of a different sort, cultural reflections of a community’s beliefs over time and markers of historical events such as battles, influenza pandemics, conflagrations, failed sea voyages, and political movements. I speculated about the lives and deaths of unknown soldiers who died at remote frontier posts and were buried far, far from home. I mourned children who died too young. But over time it became apparent that cemeteries were miniature bio-habitats as well, serene places with gnarled trees, which offered squirrels and other critters relative safety from human predators. Sometimes vistas joined them visually and physically with natural worlds beyond their fences.
Designers of the landscaped urban cemetery movement, which started in the United States in 1831 with Mount Auburn Cemetery in Cambridge, Massachusetts, were inspired not by biodiversity but by a different concept of nature – one where nature was idealized and sought out as a contrast to increasingly crowded and noisy towns and cities. Mount Hope reflects that same philosophy.
“For hundreds of years, you’d have a little fenced [burial] plot next to a church,” Klatt explains. But then in the mid-nineteenth century, for reasons of public health and overcrowding, burial grounds began to be moved from church grounds to locations outside of population centers. This was also a time when there was, as Klatt says, “a lot of interest in plants” and “when landscape architecture was coming of age.” Cemeteries located close to cities, both in Europe and the US, began to be consciously designed as quiet spaces that offered sanctuary and solitude, where the living could commune with the dead in a quasi-natural environment.
Those pioneering cemetery designers were horticulturalists dedicated to landscaping as a profession. In the US, they “planted a whole lot of things including, in the beginning, edible plants, and [explored] what tended to thrive in New England and what wouldn’t,” explains Cornell University historian Aaron Sachs, who has researched the history of Mount Auburn and other urban cemeteries of that era. As he wrote in a study of Mount Auburn, “The very term ‘cemetery,’ which was uncommon until the 1870s, marked a new cultural attitude: previously interred in the neglected burying ground of churches, American urbanites would now rest in carefully maintained, secular landscapes, public places that were meant to be reposeful for both the dead and living.”
“I think they had a sense of them as islands, but not as arks for biodiversity,” Sachs told me. “More as islands to preserve the kind of feeling that was starting to be hard to get in cities, the feeling you get in the countryside when you’re walking over a lot of terrains and are aware of the ponds and the fields.”
Landscaped or otherwise, cemeteries draw far less scientific attention as biodiverse habitats than parks, farms, or forests. But biologists who do venture among the tombstones, mausoleums, and artificial flowers are making startling – and significant – discoveries. As a group of German scientists who catalogued flora and fauna in Berlin’s 97-acre Weißensee Cemetery put it in a 2016 research paper: “Cemeteries are clearly understudied, although this land-use type is ubiquitous in cities all over the world. Cemeteries are important components of the urban green infrastructure, simply because of their number and the area they cover.”
Cemeteries represent, in many cases, the last remnants of greenery in large cities.
What did they find in the largest Jewish cemetery in Europe, which dates back to 1880? Well, 363 type of wild-growing vascular plants, 72 kinds of lichens and mosses, 34 species of birds, 5 types of bats, 64 spider species, 39 ground beetle and 5 harvestman (daddy longlegs) species. Those numbers are probably incomplete, the researchers say, especially for insects. But the diversity of biota tells only part of the story. What stands out to me are species they identified that are threatened, critically endangered, or near-threatened on the International Union for Conservation of Nature’s Red List, as well as those previously undetected in Berlin, or considered extinct in the city. These include 25 plant species of conservation concern and 9 protected species of bird, such as the green woodpecker, goshawk, and spotted flycatcher. All of the bats they detected were listed as either vulnerable or endangered on the IUCN Red List. Of the arthropods, two species were threatened, two were new discoveries for Berlin, and one species, Agonum gracilipes, a ground beetle found throughout much of Europe, had previously been considered extinct in the city.
Based on those findings, the researchers concluded: “Old cemeteries within a large city can harbor a considerable biological richness and therefore may play an important role for urban diversity conservation.”
“Typically we think of cemeteries as being flat and open, with highly manicured lawns, maybe with a canopy of trees but pretty simplified vegetation,” says Steven Latta, director of conservation and field research at the National Aviary in Pittsburgh. “At least in Pittsburgh, that’s less the case because of the topography. We have a lot of hills.” And that, he says, draws birds: “A lot of cemeteries wrap around steep hillsides, and it’s that heterogeneity of habitats that’s providing habit for birds,” he explains.
Latta’s team examined 150 sites in 53 cemeteries and parks in the city for the relationship between “habitat patch dynamics” and avian communities. Of the 61 bird species detected at these sites, 27 are rarely seen in the Pittsburgh area, including the hairy woodpecker, black-throated green warbler, and chestnut-sided warbler. “I was surprised by the diversity,” Latta told me. The team found that richness of species in a particular habitat, including the number of rare bird species found, was significantly higher in bigger parks and cemeteries, proving that scale matters when it comes to supporting species diversity.
Additionally, these sites provide safe routes for species passing through urban landscapes. A City University of New York researcher found that cemeteries and roadway medians can provide “dispersal corridors” for native wildlife. “Maintaining migration between fragmented populations is a key goal of conservation genetics,” Jason Munshi-South wrote in his study of gene flow among white-footed mouse populations in New York City. Those mice, he observed, can “occupy or move through even the thinnest, marginal green spaces” such as cemetery edges. Obviously, fauna such as insects, amphibians, mammals, and birds have a much better shot at moving from island to island using these connectors as stepping stones than do plants that often have to piggyback their way to new habitats.
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A growing body of evidence points to the important role cemeteries play when it comes to urban species diversity and conservation. (photo Paul Hurtado)
About 4,500 miles and an ocean away, scientists in Bratislava, the capital of Slovakia, also confirmed the importance of urban cemeteries to species diversity. Their search for breeding bird populations in three city cemeteries found 33 species, including the European greenfinch, black redstart, and Eurasian tree sparrow, with the highest number found in the smallest, most isolated cemetery – not coincidentally, the one with the oldest trees that provide hollows for nesting and with the most diverse vegetation. “Cemeteries represent in many cases the last remnants of greenery in large cities,” the Slovakian scientists observed in a report. “These habitats provide food and suitable nesting places for some bird species adapted to urban conditions.”
Some of the most intriguing research into the role that cemeteries play in safeguarding flora biodiversity is being done by a team of Hungarian scientists led by botanist Attila Molnár of the University of Debrecen. Molnár’s team has conducted botanic surveys in more than 2,200 cemeteries in 13 European countries since 2014, with fieldwork in two more countries – Greece and Poland – on the horizon. Their work has produced some surprises.
In Turkey, for example, they found at least one orchid taxon (family) in 208 of the 300 cemeteries surveyed. The “silent guardians,” as they described these graveyards, contained 49.4 percent of the country’s total types of orchids, including rare and threatened ones. That astounding diversity is imperiled, however, by agriculture, overgrazing, and illegal collection of salep – orchid tubers ground up to make flour for beverages and dessert. “Although we thought previously that graveyards might be safe against salep harvesting, we detected signs of digging orchid tubers in ten graveyards in six provinces,” they wrote in a 2015 study.
Though their surveys focus primarily on orchids – the biggest group in the plant kingdom – they also examined the surprising rediscovery of scalloped spirea, a relic plant of the steppes that had been classified as extinct in Hungary at the start of the twentieth century but was found again in 2000 in a village cemetery. The team’s botanical survey of 294 graveyards in the country’s Pannonian ecoregion found 12 new sites where that species survives, plus “valuable populations” of 27 other protected plant species.
Even more intriguingly, based on data from 166 Albanian cemeteries, Molnár’s team concluded that religion is an apparent variable for biodiversity, with Christian cemeteries containing fewer orchid taxa than Muslim ones. The researchers weren’t sure why this was so, but cited prior research suggesting a possible explanation: Christian cemeteries are more heavily maintained while Muslim ones have “less intensive land use activities (such as grazing, mowing, harvesting of medicinal herbs, etc.), since these are sacred places.”
“Albanian graveyards can be considered as significant refugia for orchids in the Mediterranean, and the long-term graveyard management influenced by the religious affiliation may have a significant impact on the natural values of these graveyards,” they observed.
Sometimes nature reclaims its own in its relentless demand for survival. That’s what I saw at Todd Cemetery, tucked into a forest opening along a gravel road in Indiana’s Hoosier National Forest. Just as the homes of those who lived nearby in the late 1800s and early 1900s have reverted to the wilds, so too has their final resting place lost the battle for permanence. Relentless weather erases tombstones. Plastic flower bouquets fade into pale pastels, then crumble. The forest presses in.
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Many cities have begun managing cemeteries with their ecological value in mind. (photo: Adrian Scottow)
Often, we humans try to counter this process of reclamation. Val Plumwood, the late Australian ecofeminist and self-described “biodiversity activist,” underscored the hazards of human intervention and best intentions in a moving description of the orchids that once grew at the small cemetery a mile beyond the New South Wales village of Major’s Creek. There, where she would eventually bury her son, she witnessed “the miracle that transfigures the cemetery each spring, which turns ancestors into orchids.” It was, she wrote later of the discovery she’d made in the late 1970s, “a sheet of purple and gold, a mass of native orchids of mixed species growing so thickly it was difficult to walk without treading on them.” Among them, the critically endangered Major’s Creek leek orchid that’s found no place else.
Within a few years of that discovery, most orchids from the endangered remnant plant community had disappeared as the result of the Major Creek Progress Association’s restoration and beautification project. Plumwood mourned their disappearance as “the extinction processes of progress,” the paving of paradise with memorials atop “massive slabs of concrete fancied up with surfacing stone.” Native plants were also killed by weedicides, and lawns were expanded, resulting in a “thistle invasion not unconnected with the herbiciding of the suffering soil surface.”
“The war against nature is waged under the banner of tidiness, order, and respect,” Plumwood wrote in a 2007 essay. “Although cemeteries can be places of high biodiversity, this has been due more to human neglect than to human care.”
Hungarian botanist Molnár, who has come to a similar conclusion based on his study of European cemeteries, cautions against the idea that cemeteries can be absolute guardians of biodiversity. Valuable flora in traditionally managed cemeteries, which didn’t rely on modern machinery such as electric mowers and chainsaws, are already “in great danger,” he writes. “Unfortunately, the traditional management, such as mowing by hand, is disappearing, [and] original and native vegetation is being replaced with planted evergreens.” Most of the graveyards his team has studied have plans to eventually “modernize,” which means replacing traditional grass-covered graves with concrete, marble, or granite tombs. “This ‘westernization’ process is general and probably unstoppable,” Molnár writes.
But then again, maybe not. In recent years, many cities and cemetery managers have begun to recognize the value of these unintended habitat havens and are managing cemeteries accordingly. In England, for instance, at least nine cemeteries across the country have been declared “local nature reserves” by Natural England, a public body sponsored by the United Kingdom’s environment department. While some of these cemeteries are no longer in use, others work to maintain a balance between nature conservation and running a working cemetery. That means, for example, allowing old parts of the site with few visitors to go wild, to stop mowing the grass around headstones to allow wildflowers to grow, or letting dead trees decay where they fall.
London’s Abney Park cemetery is one such popular graveyard nature reserve set amid a sea of roads and concrete. Situated just 5 miles from the heart of the city, it was originally laid out by Victorian horticulturalists in 1840 as an arboretum. The 32-acre woodland cemetery is now home to around 200 old trees that provide sanctuary to bats, owls, and other wildlife. It also has remarkable diversity of insects and fungi, including many nationally rare species. Since the 1980s the cemetery has been managed as a woodland memorial park and nature reserve that balances its unique urban wilderness with its historic role as a graveyard.
So too is it balanced at Michigan’s Mount Hope Cemetery. As I’ve walked along its narrow roadways, I’ve wondered about the people buried here, some of their names weathered away over the decades or obscured by lichen. And I’ve wondered at how life thrives in the unlikeliest of places. Those laid to rest here can’t hear the spring peepers or see the white-tailed deer nibbling at the grass above their graves. Fortunately, we can.
Given their comparatively small size and the general lack of connectivity between many cemeteries and other habitats, it would be an exaggeration to call them “earth arks” that can rescue endangered and threatened species from the floods of extinction and carry them to salvation, or at least eternal survival. Instead, perhaps we should think of them as small lifeboats that may carry some of their desperate passengers to at least temporary safe harbors.