Contribution to landscape history in West Africa. Explorers’ and European residents’ Northern Rivers of the 1830-1910 periodOwing to early European settlements, the Northern Rivers region represents a privileged historiographic field for the historical ecology of the forest-savanna gradient along with the Dahomey Gap. Examination of the social, political and professional context of accounts published by late XIXth century explorers opens a window on their perception of the landscape. Contrary to contemporary ecology’s scientific nomenclatures, their descriptions contain information about the sensory experience of the environment which allows to infer the vegetation physiognomy. A sawtooth evolution of forest cover expansion can be traced from natural resources inventories in areas under colonization. These oscillations, which are caused by a concurrence of demographic, economic and political factors perceptible in these texts, are compared with XXth century anthropic dynamics of vegetation cover in other Western areas of the forest-savanna gradient. Present-day conservation policies based on a parallel between forest and nature to be preserved on one hand, as opposed to savanna and cultures to be civilized on the other hand, seem to fit with a kind of environmental sensitivity which is already expressed by certain explorers.