Neighbor's tree - Security and dirt. Who is responsible?

Depending on how reasonable the neighbor is and how much you care about a good relationship, I would do it this way. Inform him in writing or in the presence of witnesses that the trees are dead and pose a danger, and that he must fulfill his duty of traffic safety. If that does not help, proceed under [§ 1004 Abs. 1 Baugesetzbuch], but only after legal advice.

If the trees are dead or so sick that it becomes dangerous, they must be removed.

Search for the conversation again. Just ask him directly why the trees should remain even though they are sick?

Honestly, I wouldn't take any action without a lawyer. In the end, you might still be to blame because you removed a twig that is at least "45 cm" thick.

Even if you didn't want to talk about the fence, count 10 panels stacked on the photo. Since a panel is 20 cm high with welded wire mesh, that comes to 200 cm.

If experts say that they are really dead and must be removed, I would address that again with this background and if that leads to nothing, seek information/advice on whether and how that can be enforced.

You can share costs with those who also want the trees removed.

There are no obligations to respond, especially not within the short intervals mentioned. Don't let it annoy you, these are recurring individual opinions.

OK, then the neighbor seems to be stubborn. But if the others also want the trees gone, maybe it will help if you team up?

Even if you didn’t want to talk about the fence, count 10 panels stacked in the photo. Since one panel of wire mesh fences is 20cm high, that comes to 200cm.

There are nine ;) You can’t tell, but the last panel was added later. Unfortunately, too much topsoil was removed, so the fence ended up being higher later.

In my first response, I assumed that there was still some life in the trees above. Otherwise, as I have already written, they should be removed.

It is normal for trees to sway in the wind, especially at this height.

I would never remove branches from foreign plants, even if the owner agrees. Because if the plant dies afterwards, the person who cut it might be blamed by the owner, even if the cutting had nothing to do with it.

Furthermore, it should be considered that if you remove branches from only one side of the trees, there will naturally be a higher weight on the opposite side, which can cause such a tree to fall in the direction of the heavier side. Thus, in the direction of the buildings. I would not rule out that the person who removed the branches might also get more or less a lot of trouble.

Therefore, I would always let the owner do this.