Some Koreans are hoping that the demilitarized zone (DMZ) between North and South Korea will be turned into a nature preserve. The 155-mile-long DMZ — laced with landmines, razor wire, and chain-link fence — has been cut off from human interference for nearly half a century, so many plants and animals are thriving there, including some endangered species. Military borders in other regions have been turned into “peace parks” to promote reconciliation — Laos, Vietnam, and Cambodia share such an reserve, as do Nicaragua and Costa Rica. But the reserve plan will have to compete with proposals from South Korean companies that want to build facilities in and around the DMZ.