4. yes.
Simultaneously? Are they also still waiting for the rejection notice?
3. Here lies the "rub" - I don't know that.
Can you explain the following statement?
The nature conservation authority has also approved this preliminary building notice
Which authority made what statement?
5. I am planning myself, want to build with Heinz von Heiden.
So you are authorized to submit building plans? I think your problem is not based on building law, meaning the planned use of the areas is not preventing the construction project, but rather the local tree protection ordinance. With the existing preliminary building notice and a coalition of the four builders, it should be possible to negotiate an environmentally compatible compromise. Perhaps the building application simply lacks sensible compensation proposals for the felling permit. Of course, the forester acts as an advocate for the trees - who else? That's his job. If you want to go after "his" trees (or rather their roots), then you have to make qualified proposals on how you intend to compensate for this environmental damage. So study the tree protection ordinance, which certainly includes possibilities for obtaining a felling permit, and justify in detail for each tree why it must be removed and how you will compensate for it.