The fence looks to be made from lots of very thin plastic rod. It has too much roundness to be PE. 2 long lengths laid flat and the small ones laid with equal gaps. The points are squeezed flat and pointed first (?) using pressure or heat or both.
The grass could be some brand of static grass.
The trees look to be using some tree frame, from a root system or small tree with lots of branches .... possibly even a wire frame and then using white glue and some dried herbs.
These are all guesses, as I dont know what they are actually made off. I have seen the dio before, recently on missing links. Maybe if you checked back a bit, you could find the builder and contact him for the proper methods. It would also be possible to build them from the methods above!!