The Nimba Range is a narrow ridge of Precambrian rock stretching roughly 40 kilometers along a northeast-southwest axis, part of the southern extension of the Guinea Highlands. Its highest point, Mount Richard-Molard at 1,752 meters, stands at the tripoint where Guinea, Liberia, and Ivory Coast meet -- though the name 'Mount Nimba' is sometimes used for the peak and sometimes for the entire range. Other summits follow close behind: Grand Rochers at 1,694 meters, Mont Sempere at 1,682 meters, Mont To at 1,675 meters. The underlying geology is ancient granite and quartzite, and it contains something that has shaped the range's modern history as much as its biology: significant deposits of iron ore. Mining interests have pressed against conservation boundaries for decades, and the tension between extraction and preservation remains unresolved.

Walk up the Nimba Range and you walk through distinct ecological worlds. Below 600 meters, Western Guinean lowland forest blankets the base, dense and humid. Between 600 and 900 meters, lower montane forests of Lophira and Terminalia take over. Above 900 meters, near-daily clouds feed mossy forests dominated by Guinea Plum trees and draped in epiphytes, including an orchid -- Rhipidoglossum paucifolium -- found nowhere else. Higher still, the trees give way to montane grasslands where the grass Loudetia kagerensis dominates and Protea shrubs cling to the windswept slopes. Each zone harbors its own endemic species: plants like Osbeckia porteresii and Blaeria nimbana in the grasslands, the Guinea Screeching Frog in the high meadows, and chimpanzees on the lower slopes that use stones as tools -- a behavior documented in only a handful of primate populations worldwide.

In 1943, the colonial government of Ivory Coast established a Strict Nature Reserve covering the range's western slopes. Guinea extended protection to its side the following year. Both nations maintained the reserve after independence, and in 1981 and 1982, UNESCO inscribed the Mount Nimba Strict Nature Reserve as a World Heritage Site, also designating it a biosphere reserve. But the listing came with an asterisk: by 1992, the site was placed on the World Heritage in Danger list, primarily because of iron ore mining concessions that threatened the Guinean portion. The Nimba viviparous toad, Lamotte's roundleaf bat, Myotis nimbaensis -- a bat species not described until 2021 -- and the Nimba otter shrew all depend on habitats that mining could fragment or destroy. The range sits at the intersection of extraordinary biodiversity and extraordinary mineral wealth, and the outcome of that collision is still being decided.

From the summit grasslands of Mount Nimba, the view drops away in every direction into lowland forest that stretches unbroken to the horizon. On clear mornings, before the clouds build and the mist rolls in, you can see across three countries from a single point. The light at this altitude has a particular quality -- sharpened by thin air, it picks out the iron-red soil of exposed ridgelines against the deep green of the forest below. BirdLife International has designated the entire range as an Important Bird Area, and the skies above the grasslands are active with raptors and endemic species. At ground level, the pygmy hippopotamus and zebra duiker -- both endangered -- move through the lower forests. The Nimba Range is not a single ecosystem but a stack of them, compressed into a 40-kilometer ridge, each layer depending on the ones above and below it.