Kẻ Gỗ occupies roughly 35,000 hectares of hill country in southern Hà Tĩnh, split between a strictly protected core of about 24,800 hectares and some 10,400 hectares of protection forest, spread across the uplands around Cẩm Xuyên and Hương Khê. The Hà Tĩnh People's Committee established it by Decision No. 519/QD-UB, dated 3 May 1997, and the decision named its purpose plainly: safeguard the imperial pheasant and the Vietnamese pheasant, and the biodiversity of the province's southern forests along with them. Both names have since dissolved under scrutiny. The Vietnamese pheasant, Lophura hatinhensis — described from this very province, its white tail feathers giving it the local name gà lôi lam đuôi trắng — is now understood not as a distinct taxon but as a variant of Edwards's pheasant, produced by inbreeding in a population that had grown too small to avoid it.

Strip away the hybrid and the inbred morph and one real bird remains, and its situation is worse than either of its shadows suggested. Edwards's pheasant is endemic to a narrow band of lowland forest in central Vietnam, and the last confirmed sighting of a living wild individual was in 2000. In 2018 a photograph documented a dead female in A Lưới district — evidence of a sort, and not the sort anyone wanted. The IUCN assessment that year listed the species as Critically Endangered, with somewhere between 50 and 249 mature individuals possibly surviving. It breeds readily in captivity, which is the only reason there is a species left to argue about. Whether the forest at Kẻ Gỗ still holds any is an open question, and a reserve founded on two taxonomic mistakes has ended up protecting exactly the habitat that the one genuine bird requires.

The reserve wraps around a lake, and the lake came first. French engineers had drawn plans to dam the Rào Cái here, but the Second World War and then the First Indochina War buried the project. Vietnamese engineers took it up in 1976, a year after reunification, and the work became one of those national efforts that people volunteered for and remembered afterwards. The main structures were finished by 1980 and the scheme was fully operational in 1983: one principal dam, three auxiliary dams, a reservoir holding over 300 million cubic metres across roughly 30 square kilometres and stretching nearly 30 kilometres up the valley. The composer Nguyễn Văn Tý wrote a song about the people who built it, "Người đi xây hồ Kẻ Gỗ," and it is still sung in Hà Tĩnh. Few reservoirs anywhere have their own anthem.

Kẻ Gỗ protects one of the last stands of lowland rainforest left in Vietnam, which is why the species counts matter. A 1999 survey logged 46 mammals, 270 birds, 562 plants and around 100 reptiles and amphibians; the German biologist Thomas Ziegler has documented a herpetofauna of close to a hundred species here. Above about 300 metres the canopy is dominated by dipterocarps; lower down the forest runs to Michelia, Cinnamomum, and hardwoods like Madhuca pasquieri and Erythrophleum fordii. The large mammals are the conspicuous absence. Hunting pressure has been heavy enough for long enough that elephants are almost certainly gone, and tigers and gaur with them. Reserves like this one tend to be described by what they contain. Kẻ Gỗ is also defined by what has already been taken out of it.

The management board runs to about seventy people, fifty-six of them rangers, against illegal logging, snaring for the wildlife trade — domestic and international — and pressure from oil exploitation. The Netherlands and the German conservation foundation ORO-VERDE have both funded work here. There has been at least one clear gain: in 2017 the Endangered Primate Rescue Center released four Hatinh langurs into the reserve, part of a programme to return a leaf-eating monkey with a striking white side-whisker to forest it had been emptied from. Four animals is a small number against 35,000 hectares. It is also the difference between a forest that has lost a species and one that has not quite.