"The African Union is seeking support to fund a range of actions aimed at protecting fertile lands from the advance of the desert, largely through planting trees ... It's a laudable aim, but ... [previous] attempts at planting trees have been costly mistakes ... A green wall needs to be built of diverse blocks, a medley of bricks in every shade of green ... drawn from local materials, knowledge and skills. Instead of planting trees, such a wall needs to grow from natural regeneration of local seedlings." (Quoted from article)