Planting trees is one thing- but keeping them alive in the dry circumstances of Southern Portugal is another challenge. This is why we use various methods to protect the (soil around the) trees by growing vegetables, mulching and making sure no farm animals eat them.
Sheep for example love the leaves of young trees. The trees don't like them to be eaten though. So when the sheep were grazing around the trees we put up a simple fence to guide the eating impulses of the sheep towards the grass.