The Green Corridor covered 1,340 square kilometers of forest in the districts of A Lưới, Nam Đông, and Hương Thủy of Thừa Thiên Huế Province — a stretch of highland territory connecting Bach Ma National Park to the forests of the A Lưới Valley and beyond into Laos. The project was a partnership between the World Wide Fund for Nature's Greater Mekong Programme and the Thừa Thiên Huế Provincial Forest Protection Department, funded by a $2 million grant from the Global Environment Facility, the World Wildlife Fund, and the Development Organisation of the Netherlands. Additional support came from the U.S. Fish and Wildlife Service for primate surveys. The logic behind the corridor approach was ecological: isolated forest fragments lose species over time because populations become too small to sustain themselves. A connected corridor allows animals to move, populations to mix, and forests to function as intact ecosystems rather than isolated patches.

Between 2005 and 2006, researchers working in the Green Corridor documented eleven species previously unknown to science. Two were butterflies — one a grass skipper from the genus Zela, another a new genus in the subfamily Satyrinae, among eight butterfly species discovered in the province since 1996. One was a snake: the white-lipped keelback (Hebius leucomystax), a slender stream-dweller about 80 centimeters long, its body dotted with red and its head striped yellow-white, living on frogs and small prey near forest watercourses. Five were orchids, three of them entirely leafless — they contain no chlorophyll and subsist entirely on decaying matter, an adaptation so unusual it makes them look less like flowers than like pale parasites rising from the forest floor. A newly identified aspidistra produced flowers so dark they appeared nearly black. These weren't marginal discoveries in obscure corners of taxonomy. They were found in forests that have been studied for decades, in a country with one of the world's most active biological survey programs.

The Green Corridor is considered one of the most important places in the world for saola conservation — possibly the best remaining location anywhere. The saola has never been observed in the wild by a Western scientist; everything known about it comes from camera traps, DNA samples from hunter kills, and a handful of captive animals that died quickly after capture. Its population is believed to be critically small, fragmented across a few forest blocks in Vietnam and Laos. The same forests hold Vietnam's largest population of southern white-cheeked gibbons, one of the world's most endangered primates. Surveys have also documented 15 threatened reptile and amphibian species and six at-risk bird species within the corridor. Leopards and tigers may persist in the most remote sections. These populations survive under pressure from illegal hunting, logging, and the encroachment of agriculture — threats that the project's 40 forest rangers work against daily.

Conservation in the Annamites is not simply about rare animals. The forests of the Green Corridor regulate the water supply for thousands of people downstream in the lowlands of Thừa Thiên Huế Province — rivers that irrigate rice fields and supply drinking water to communities that have no alternative source. For ethnic minority communities who live within and near the corridor, the forest provides more than half their income in the form of non-timber forest products: rattan, medicinal plants, wild foods, bamboo. The agreement signed in Huế on May 7, 2004 recognized this explicitly, framing conservation not as an external project imposed on local communities but as a mechanism for sustainable development that local people had a stake in. Whether that balance has held over the two decades since the project launched is a more complicated story — but the forest itself, still standing, still harboring its saola and its leafless orchids, is evidence that something has worked.