Nothing much to do with linguistics, but... Apparently (the book I was reading cites Dresch 1986), the turning point in the desertification of the High Plateaus, the dry zone forming the northern boundary of the Sahara in Algeria and Tunisia, came with French colons' introduction of European-style farming methods. Traditional cultivation methods there left the land fallow one year out of every two, and used nothing sharper than a hoe, leaving numerous clods in the soil, thus keeping erosion to a minimum. The French methods, using a much deeper digging plough and completely weeding the soil, left the soil finely powdered and ready to disappear Dust Bowl-style in the event of any major windstorms, while their expropriation of the land pushed the Algerian farmers into more and more marginal areas, removing their plant cover and rendering them more vulnerable to erosion in turn. The US' Dust Bowl formed in a rather similar way - "sodbusters" removing the crust and vegetation cover that kept the land from blowing away - if on a far larger scale. The process has continued even since independence, due to the obvious short-term financial incentive to plant more land; the result has been "increasing sensitivity to wind erosion and a general degradation of the steppe ecosystem". Nothing so far about Boumedienne's "green line"; I wonder if it made any difference?
I find this interesting in general, but particularly telling given that I recently found some online would-be expert (I don't think I'll bother to link him) boasting that French contributions to Algeria included the "introduc[tion of] modern agriculture". It's amazing how you can put a good face on something just by picking the right words - and on that note, I think I've finally found a linguistics connection for this post.