This package has (at least had at the time of the video recording) trees created using Unity Tree Editor.
https://docs.unity3d.com/Manual/class-Tree.html

To make the trees more responsive, adjust the fields in the Terrain / Settings / Tree & Detail Objects section. The main fields here are Tree Distance, Billboard Start, and Max Mesh Trees.

which prefab are used in this tutorial? https://www.youtube.com/watch?v=thFaYlu65u8

it says in the notes that it's NATURE PACKAGE but i see there is some type of tree-structure editor?

another one: when generating trees, the amount of trees is enormous and the scene rendering becomes very very choppy and slow - how would you recommend to overcome it? there might be a problem with the tree prefab that i defined?

thanks.

Try the following:
Select terrains, and set the Static - Everything (at the top of the inspector).

I've generated a multi-terrain area (4*7) with trees (generated by RWT).

I've set the terrain scale to 0.1, 0.1, 0.2 (to make trees more visible, the correct proportions are less important here).

I'm having an issue with flickering shadows - any advise?

I've tried to change the directional light biases, didn't help.

thank you