Well done Hillybilly for finding the legislation on this.
Rough translation by Google:
The Civil Code, articles 552-593 covers “590 servitudes” and I articulate is about the distances etc of trees etc from boundaries. It states that “the minimum ranges that are had to keep respect to the other people’s property, leaving except for established according to the custom of the place or applicable municipal ordinances. These distances will be of two meters for the case of high trees and fifty centimeters for the case of shrubs and low trees, whenever the decrees that in their case are of application do not establish other distances. The previous thing implies that the dueno (owner) of the adjacent property can cut the roots of the tree of the neighbor that are introduced in their property; and in case the branches of the neighboring tree are extendan on their propriedad, it can protest that they are cut. “