The European ash tree (species: Fraxinus excelsior) is commonly used in Spain as a source of firewood using the technique called "pollarding". Using this method the land owners are able to harvest decent firewood from their trees without killing them. The methods consists in cutting all the branches off at about 8-10 feet off the ground every few years. This rather severe pruning back of the tree causes it to maintain a partial juvenile state and as a result these "pollards" tend to live longer than trees of the same species that are not pollarded. It also causes the trees to grow thicker at the trunk given them a sort of swollen look. The pollarding does not kill these trees however and a new set of branches grows back to replace the ones that have been cut off. The new branches tend to be fairly long and straight which makes them useful for poles or fence posts. Since they branch off fairly close to the base it makes harvesting the next set of branches all the easier.
A similar practice to pollarding is called "coppicing" where the trees are cut off right at the base. This is used with trees that grow back easily from the stump or roots in the form of new shoots. Coppiced trees tend to have multiple trunks while pollarded trees will normally have just one thick trunk.