(CNN) War can have a devastating impact not just on human life, but also on the environment.
More than two thirds of the world's biodiversity hotspots experienced conflict at least once between 1950 and 2000, with many seeing repeated outbreaks, according to one study.
Scorched-earth tactics and chemical warfare pose particular threats to flora and fauna. But when the conflict ends, ceasefires are agreed, and troops retreat, unexpected sanctuaries for wildlife can appear in their wake.
In 1953, hostilities between warring North Korea and South Korea ended when an armistice agreement was signed. It mapped out a demilitarized zone (DMZ) between the countries that is 250 kilometers long and on average 4 kilometers wide.
A heavy military presence remains and civilians are very rarely allowed into the DMZ, but troops have found evidence of rare Asiatic black bears, Amur Leopards, and Amur gorals (a type of mountain goat) living there.
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"We call the region an accidental paradise," says Seung-ho Lee, president of the DMZ Forum, a group that campaigns to protect the area's ecological and cultural heritage. "Scientists are amazed by this reclamation by nature, regenerated by itself. So many scientists really want to research what happened for the last more than six decades. In that regard, it is a really unprecedented area."
The DMZ is home to more than 5,000 species, 106 of which have protected status, the South Korean Ministry of Environment reports. White-naped cranes and black-faced spoonbills are among the rarer species to seek refuge there, among the minefields and abandoned towns.
Lee says ecologists aren't permitted inside the DMZ, but they can get a sense of what lies beyond the fences by studying the Civilian Control Zone (CCZ) -- established in South Korea as an extra buffer below the southern limit of the DMZ. Parts of the CCZ have been designated "biosphere reserves" by UNESCO, in recognition of their biodiversity.
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Seung-ho Lee says that logging and flooding have damaged North Korean land near the border, and urban development and pollution are fragmenting habitats in South Korea. As a result, the DMZ has become an oasis for migratory birds.
Last year, North Korean leader Kim Jong Un and South Korean President Moon Jae-in pledged to "transform the demilitarized zone into a peace zone in a genuine sense" by ending all hostile acts along the border. In April 2019, South Korea opened the first of three "peace trails" for a limited number of visitors along the DMZ.
But without reunification, Lee says, the environment remains under constant threat: "Because of this tense [military] situation, the DMZ is always in danger of another total destruction by bombing."
It may seem an unlikely refuge, but it's not the only former battlefield where nature has made a remarkable recovery.
When people are forced out of conflict zones or disputed territory, "wildlife often makes a comeback," says Thor Hanson, an American biologist and author who has studied the environmental impacts of war. "You have these areas of high biodiversity that are rarely visited by people, and that is an interesting by-product of conflict."
DMZs and military training areas, where people cannot farm, build, or extract natural resources, may "inadvertently end up protecting or preserving examples of habitat that may have become quite scarce, just due to population growth," he says.
Deep in the Mediterranean Sea, the island of Cyprus is divided through the middle by a "Green Line." This partition was drawn up in the 1960s amid violent clashes between Greek and Turkish Cypriots after the nation became independent from Britain, and was extended in the 1970s following the Turkish invasion of Cyprus.
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Today, the Green Line sweeps from coast to coast, a buffer zone between the Republic of Cyprus and the self-proclaimed Turkish Republic of Northern Cyprus. Patrolled by United Nations forces, it is a few kilometers wide in some parts; in others, just a few meters.
Abandoned for decades, most settlements and farms have given way to a sprawling wilderness. "Civil Use Areas" and a few villages within the buffer zone are open to civilians, and today over 10,000 people live or work in them. In the rest of the zone, however, human access and activities are highly restricted.
The rare Cyprus Bee Orchid and the Cyprus Tulip are reported to be flourishing in the buffer zone, along with at least 356 other plant species. Mouflon, a shy species of wild sheep with curled horns, roam the region in their hundreds. The Schneider's Skink lizard, Lapwing, and Cyprus Spiny Mouse were presumed to be endangered or extinct in Cyprus until they were found thriving in the buffer zone in 2007.
Though limited, human activity in the buffer zone can still harm the environment. Fly-tipping, also known as illegal dumping, has become a serious issue, says Aleem Siddique of the United Nations Peacekeeping Force in Cyprus, and the UN organizes clean-up operations along the DMZ's two beaches.
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Siddique says the UN forces have a "delicate" role in Cyprus. "We're doing our best to preserve and protect the unique environment within the buffer zone -- its landscape as well as its diversity of flora and fauna -- not to mention safeguarding its history in light of the current peace talks, while supporting an overall return to normal conditions," he says.
Caring for the island's habitats can also help promote peace, says Siddique. "The environment has the ability to act as almost a catalyst, bringing the two communities together to work together for a common cause."
Barbed wire cuts through the Golan Heights, a rugged plateau that separates Israel and Syria. The "Purple Line" border between the two countries was created after the Six-Day War of 1967, when Israel captured the Golan Heights from Syria. Here, the UN controls a demilitarized zone measuring over 230km².
Only a handful of towns and villages still stand in the DMZ, also known as the "Area of Separation," and they are heavily guarded by checkpoints and patrols. Few people are currently allowed to cross the line. Yet beyond the fortifications and minefields, UN peacekeeping forces report that there is "beautiful but dangerous fauna and flora."
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The Golan Heights -- and Mount Hermon, which dominates the northern half of the buffer zone -- are home to oak and terebinth forests, rare orchids, wildcats, gazelles, hyenas and wild boars. Mount Hermon hosts about 100 species of butterfly, according to the Israel Lepidopterist Society, including a previously unknown species identified in 2017.
But larger creatures also cross these borders. The buffer zone and its fortifications shelter wolves and vultures from hunting, according to Shmulik Yedvab, of the Society for the Protection of Nature in Israel.
However, Yedvab says the fortified border fragments habitats for many migratory species. An estimated 500 million birds travel through Israel twice a year, from Europe and Asia to African wintering grounds, with the Golan Heights providing an essential refuge. "In the long run, we should all, I think, pray for the fence to be diminished, or at least to have some access for ecological corridors or passages between both sides."
Outside of the buffer zone, the Golan Heights still bears traces of its violent past. The rare Golan Wolf even seeks out the minefields, where humans cannot enter and most animals are too light to trigger explosions, according to Yedvab.
Every few kilometers, disused military bunkers have attracted an "amazing" array of wildlife, Yedvab says.
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"It's bats mainly, in the darkness of these man-made caves -- but also porcupines, foxes, owls and others, it's beautiful. Every time you go to one of these bunkers, there is always a surprise to see," he says. "As long as there is peace, these bunkers will serve the wildlife better than humans."
While nature heals in these former conflict zones, paradoxically it is protected by the tensions between nations. If peace is restored and the DMZs are removed, what would happen to the wildlife living in them?
Lee acknowledges that reunification in the Korean peninsula could one day open up the DMZ to new perils.
"There is a threat from people's greed for development in both North and South Korea," he says. "There are always people who want to see land for the economic benefits, at the expense of nature."
But still, he feels reunification is essential to protect the DMZ from further conflict. What's more, he believes that a desire to protect its natural habitats could help to secure lasting peace. "We'd like to use this environment as a diplomatic tool to build trust," he says, "and then see the two Koreas reunited in a peaceful way."