Generally speaking, each off-forest tree system faces its own specific constraints, but some obstacles to development are common to all. These include: the complex legal status of land, the fact that plantations are scattered, poor plant matter and farm practice performance, the lack of water, and so forth. The woody biomass yield of local and introduced species is low. Meeting the demand for biomass fuel raises the problem of mounting need coupled with ecosystem degradation. Carob trees, multi-purpose trees in pastoral and mountainous zones, and date palm culture in oasis and pre-Saharan zones are all sectors suitable and advisable for development. The best species and land use interactions also need to be identified.