When biologist Yuval Itescu moved from Israel to Germany, he noticed something different about his new host country. He explored Berlin just as any visitor would, taking in the vibrant life of its streets and shops and the calm quiet of its parks. But he also found himself drawn to a different aspect of the German capital: its urban cemeteries. 

“I started taking walks there and spotting a diversity of wildlife—birds, invertebrates of different kinds, squirrels, and foxes,” Itescu said. “This got me reading about biodiversity in cemeteries and other urban sacred sites, and I realized two things: This is a fascinating topic that involves both ecological and human dimensions, and there is relatively little research on it.”

Cemeteries are a paradox in the modern Western world. On one hand, they are widely seen as calm and comforting spaces, places to grieve but also quietly contemplate in a world that offers few such chances. But their association with death—and decades of horror films and suspenseful TV shows using them as backdrops—can make them unnerving places. This same complicated relationship extends beyond the human experience of grave sites. For the nonhuman world of plants and animals, cemeteries can be sources of both refuge and danger.

Itescu, along with Jonathan Jeschke of the Freie Universität Berlin, published a paper earlier this year reviewing the biodiversity value of cemeteries and comparing it with other urban spaces like parks and botanical gardens. They found that cemeteries tended to host more native species than city parks, which were often landscaped with non-native or even invasive plants. Parks had their own advantages and contained slightly more species overall, but cemeteries proved to be important plant and animal havens in urban areas, including for endangered species like orchids. It’s one of the first global reviews of the biodiversity of cemeteries, with data from 50 cities in 27 countries.

A high-level study like Itescu and Jeschke’s can tell us a lot about the overall value of cemeteries to wildlife, but there is so much variety in the size, age, and management of individual sites that further inspection can provide even more insight into these unnaturally natural urban oases.

The rural cemetery as we know it, with its parklike landscaping and winding walking paths, is a relatively modern concept, only about 150 years old. Mount Auburn Cemetery in Cambridge, Massachusetts, is one of the oldest and most visited burial sites in the United States. It was among the first in the country to embrace this new type of design. For its architects, Alexander Wadsworth and Jacob Bigelow, the cemetery was not just a place for the deceased to rest. Rather, it could also be a destination for loved ones and others to visit.

Their design is rare among cemeteries not only for its age and claim to fame but also because it employs a full-time ecologist—Paul Kwiatkowski. When he first came to Mount Auburn in 1999 to work in the greenhouse, the cemetery’s president allowed him to experiment with improving the water quality in their ponds and then collect rainwater to reduce their groundwater usage. Over time, those small steps added up to a more conservation-minded way to manage the whole site, drawing the attention of other experts who wanted to help.

“We invited ecologists, biologists, hydrologists, landscape designers, and herpetologists,” Kwiatkowski said, “and we got everyone together to walk around the cemetery, to have conversations and evaluate where we stood with what we had been doing to improve habitat and create a balance between natural and manipulated areas.”

Today, the 175-acre cemetery is home to a huge variety of wildlife and hosts researchers from around the country studying its flora and fauna. Animals like bats, coyotes, foxes, and raccoons frequently roam the grounds. And it’s become one of the most diverse birding sites in the Boston area, enticing warblers, owls, flycatchers, and other resident and migratory species.

In Rochester, New York, another historic cemetery also works to enhance biodiversity and support wildlife while maintaining a visitor-friendly and respectful experience. Mount Hope is the largest cemetery in Rochester and, in fact, houses more graves—over 375,000—than people who currently live in the city. Some of its most famous residents include Frederick Douglass and Susan B. Anthony. 

Kristine Klein is president of the Friends of Mount Hope, a nonprofit group that organizes volunteers to both maintain the cemetery and educate the public about it. She points out that the land has been home to wildlife even longer than it has been a cemetery.

“It was total woodland to begin with,” Klein said. “There were bears and all sorts of wild animals there. So it’s been a pretty rustic place for a long time.” The cemetery was once well outside of city limits, but Rochester has grown around it, turning it into an island of vital habitat surrounded by urban streets.

In recent years, more cemeteries worldwide have focused on their ecological roles, both for conservation and research. In Green-Wood Cemetery in Brooklyn, a scientist recently discovered an entirely new beetle species. A 2019 study of parks and cemeteries in Illinois revealed that trees in the cemeteries hosted three times more woodpecker holes than the same trees in local parks. In Turkey, scientists studying satellite temperature data found that cemeteries were up to 3°C cooler than the surrounding area because they maintained more trees, helping to offset the urban heat island effect of pavement and concrete in cities. And in Britain, where old-growth yew trees have become rare and endangered, more than half of the biggest yews now exist in church graveyards.

But the ecological story of cemeteries isn’t all big trees and birdwatching. They can also be a source of potentially harmful pollution, both from the buried remains themselves and the vessels used to bury them.

According to the Green Burial Council, a nonprofit organization that encourages more environmentally friendly burial practices, the US uses 4.3 million gallons of embalming fluid each year. About a fifth of that is made up of chemicals like benzene, methanol, and formaldehyde, which have known health and environmental effects. Remains can also be sources of pollutants, including emerging toxins like pharmaceuticals that are just beginning to be exhaustively studied.

Coffins and other burial containers also use 20 million board feet of wood a year, much of it varnished with more preservative chemicals, as well as 1.6 million tons of concrete, and thousands of tons more of steel, copper, and bronze. With all the toxic materials, research suggests, these seemingly peaceful places can pollute soil and water, especially in places with high water tables and in wetter climates.

The use of embalming preservatives and other polluting chemicals is, just like the rural cemetery, a fairly recent phenomenon. Until the Civil War, most people in the United States died at or near home and so were buried quickly with no need for preservation. When the war caused so many to die far away and necessitated long, slow journeys home, embalming became a more popular solution. The national tour of Abraham Lincoln’s embalmed body after his assassination further popularized the method. Studies by the World Health Organization and others show that the placement of a cemetery, especially in regard to groundwater, can remove or mitigate many of its worst environmental dangers. Overall, some of the most environmentally damaging aspects of cemeteries are recent choices, and that means that they can be reversed.

Today, “green burials” are becoming more accessible and popular, and their once exorbitant costs are coming down closer to those of traditional methods. Green burials are more than just chemical-free and encompass a range of options, from burial shrouds that encourage fungi to grow and decompose the remains to caskets made of untreated and more quickly biodegradable materials. More than ever, the benefits of the cemetery to wildlife are growing, and the costs are becoming more avoidable, giving some hope that the cemetery of the future could be less scary and more welcoming both for people and the wild species that call them home.