How to prune a tree

When you decide to prune a tree you must remember that, in the case of a hard pruning, you will kill the tree roots in the same proportion of the branches you cut. That happens because the tree always keeps a one to one ratio between roots and branches. It's like a factory with two departments: the first department (the roots) collects the raw materials, and the second department (the branches) works those materials. If it happens that the second department, for any reason, has a lack of staff and is not capable of working all the materials the first department collects, the boss decides to fire some employees in the first department to rebalance the ratio. The tree is a ruthless society, and if you prune it wrong it's going to become a rootless society too. Which makes the tree itself not really stable.

Roots are important. Not just for trees, but for people too. Don't forget your roots. Never.