Gabrene, Bulgaria | 

Where 30 years ago barbed wire guarded the Bulgarian border, tourists now hike in a nature park filled with rare flora and fauna, part of a surprising legacy of the Iron Curtain which once ran across this region.

Sweet chestnut forests and meadows cover the northern slopes of the Belasitsa mountain range in the EU member's southwest, where access even for locals was once subject to special permission from the authorities.

As a result, nature was left to rule untroubled for 45 years until the fall of the Iron Curtain in 1989.

"After the border fences were removed, they revealed the area's well preserved biodiversity heritage," Dobriel Radev, the nature park's director, told AFP.

Nestled under the 1,880-metre (6,170-feet)-high border peak of Tumba, on the crosspoint of Bulgaria, Greece and North Macedonia, the village of Gabrene has been completely transformed from a strictly guarded outpost to a tourist attraction.

A patch of the old border fence and a rusty army observation tower can still be seen on Gabrene's outskirts, and elderly villagers eagerly share their memories of that time.

"Our everyday life was subject to strict control," said Stanimir Samardzhiev, a former local Communist party official and retired mathematics teacher.

"Villagers had to show their ID before they could work their fields" beyond the fence, he said.

- 'Gains for all our losses' -

Belasitsa, which was declared a nature park in 2007, boasts 1,591 plant species, including 28 which are protected, as well as foxes, roe deer and wild boars.

"There are gains for all our losses," said park expert Sofia Ilkova, who was one of the first biologists to discover the Bulgarian border region after the fall of the Iron Curtain.

"The animals lived without being disturbed, and the steep terrain did not encourage agriculture so no insecticides were used," she said.

Rare plant species found in Belasitsa's grassy meadows include the wild lily with its bright yellow flowers.

Just across the border in neighbouring Greece, where Belasitsa is called Belles, lies another protected area that also benefited from the Iron Curtain era -- the Kerkini Lake national park.

In late September, pelicans, cormorants and flamingoes could be seen at Belasitsa as buffalo herds grazed in pastures around the water lily-covered swamps of the park.

- 'Symbol of cross-border cooperation' -

Both parks are part of the European Green Belt -- an initiative that aims to promote sustainable development, tourism and local traditions along the whole 12,500 kilometres (7,800 miles) of the former Iron Curtain.

Belasitsa park director Radev said the "unique ecological route shared by 24 countries is a symbol of cross-border cooperation".

Today the inhabitants of Gabrene and the other villages at the foot of the mountain rely on green tourism, welcoming hikers and cyclists in several renovated traditional houses.

A bike track runs along the former frontier.

"It's hard to imagine that Greece and Macedonia were considered enemies 30 years ago," said one Bulgarian teenager, part of a group of Bulgarian and North Macedonian high school students marking European Green Belt Day in September with a birdwatching boat trip on the Greek side.

But the verdant landscapes that have replaced the Iron Curtain is not immutable.

Environmental advocates point to threats, such as the construction of hydroelectric power stations and motorways, enlargement of ski resorts and intensive logging.

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