In the sudano-sahelian zone of North-Cameroon and for more than a century farmers have been building multipurpose agroforestry parklands, which are either cropped, under fallow, or grazed, and provide various products. Until the 90's, technical advisory structures have ignored these parklands, and even encouraged tree clearing from field, for trees hamper animal draught or mechanical tillage for cotton cultivation. From 1985 onwards research stressed the interest of local agroforestry species; but only in 1996 did the DPGT (Farmer's Development and Territory Management) project attempt to induce tree (Faidherbia albida, Prosopis africana) resettlement in the fields, by subsidising retaining of every new tree. The study shows that farmers hold firm knowledge of tree and parklands management, and that tree retaining and parkland area increase. However, this evolution hangs on the ability of local organisations to take over from DPGT for subsidy management and to reach agreement with the Forestry Administration on how to rule and control tree cutting or pruning by peasants. Tree management will be improved by: (1) pursuing research on thinning, pruning and cutting practices and supporting it by modelling of dynamics of village tree resources, and (2) considering parklands as part of community forests in order to transfer management responsibility to local population, like the forest law allows it. Institutional action based on incentives to farmers can thus sustain agroforestry systems in African savannahs, thereby increasing production, biodiversity and even carbon storage.