Advice from member, professional tree surgeon, can be applied to both trees on your own property and on neighbouring property (overhanging, dropping leaves, too tall etc.) when owner refuses to cooperate.
¨I can only speak for the process in Andalusia but would hope it’s the same everywhere.
There is a blanket preservation order on all established trees and permissions are generally required. Permissions are obtained through the Medio Ambiente department at your local town hall, it should cost nothing and is simply a visit from your local MA rep, discussion of the work required – show them the problems, sign a form and post it off. The authorisation can take 6 to 8 weeks to come through (although Cordoba has a huge backlog at the moment) and will advise the timeline within which the work should be done. Failure to obtain appropriate permissions can lead to fines in the thousands so not getting permission is not really worth it. Once permissions have been obtained it is important that the tree is felled correctly to avoid damage to surrounding structures. However there are some important factors to consider if felling a live tree, particularly if the tree is situated near buildings. Trees consume large amounts of water. Suddenly felling a whole tree means the water no longer leaves the soil at the same rate. The soil expands like a sponge causing soil heave with the swelling causing structures to lift / crack etc. The soil will stabilise within a year but as the old root system rots away there will then be settlement and quite possibly sinking resulting in more damage to buildings. Influencing factors as to the severity of any subsidence and heave are soil type, clay being the worst, and the type of root system of the tree itself. The best way to address felling a live tree would be to reduce the overall size over a few years and conduct a root prune; this will allow the soil to gradually stabilise in a planned phased way.
In short:
Go to the Town Hall and tell them what you want to do.
They will send someone to have a look.
Send off the form that person gives you.
Wait for the letter back.
Get the work done (by a professional).¨