MITWITZ, Germany — A handful of crumbling Cold War-era watchtowers peek out of forests and meadows at what was once the border separating East and West Germany.
For nearly 40 years, this 870-mile-long and up to 650-foot-wide strip of land was closely guarded by Communist soldiers with barbed-wire fences,mines and antivehicle ditches to prevent would-be defectors from crossing the Iron Curtain.
But in the nearly three decades since German reunification, the area has remained relatively undisturbed and become an ecological treasure trove of biodiversity. The uninhabited land has been transformed from “a death zone into a lifeline,” according to the nature conservationist Kai Frobel.
Only a few stark reminders of the past, including overgrown concrete patrol tracks, can be spotted today in what Frobel coined the Grünes Band, or Green Belt.
“Nature essentially had been given a 40-year holiday,” said Frobel, who is considered the …