Cal Madow holds around a thousand plant species, and as many as two hundred of them grow nowhere else on Earth — an improbable tally for a country most outsiders picture as desert. The range is a limestone escarpment in Somaliland's Sanaag region, rising straight off the Gulf of Aden coast to Shimbiris, at roughly 2,400 metres the highest ground in Somalia. Its forest lives on water pulled from the sea: through winter the northeast monsoon drives damp air against the north-facing wall, where it cools into cloud. The escarpment behind the old port of Maydh gathers some 700 millimetres a year, most of it then, while the plain below gets under 200. Fog does the rest on days when no rain falls. That moisture sustains the last old-growth African juniper in the country, and on the ledges below grows Boswellia frereana — the tree whose pale resin, maydi, Arabian buyers rate above all other frankincense.
Most visits begin in Erigavo, a plateau town at 1,744 metres where December nights fall to about 5°C, a surprise to anyone who came expecting Somali heat. Tracks drop north into Daallo, the forest at the heart of the range: gnarled juniper, boxwood, red-flowered tree aloes, cloud moving through the branches. Walk to the escarpment edge on a clear morning and the ground simply ends, falling more than a kilometre to the sunbaked coastal plain. Below, harvesters are out on the cliffs, tapping the frankincense trees. Daallo is a national park on paper, but little of that protection reaches the ground: charcoal cutting and browsing goats thin the forest, and surveys have found frankincense trees carrying over a hundred cuts where a dozen is the safe limit. Sanaag is contested territory, so foreigners come on a permit, usually with an armed police escort.