In my previous video https://youtube.com/watch?v=LfYKE67f_jI I had to use performance heavy Boolean operation to change forest boundaries as well as to cut through forest. After an update to Geometry Nodes branch, it's whole another story, I can do this purely just  with Weight Masks now.
Tutorial for this video is here https://youtu.be/rd5joo1aKmk
0:00 - 0

0:12 - Controlling Valley displacement
0:38 - River is masking out forest(as well as controlling rocks scattering)
1:17 - Road is masking out forest
1:50 - Mixing Road and River masks

In this episode, we will be looking into "Point Instance" node and how we could use it with the NEW Point Cloud object via GEOMETRY NODE Modifier in Blender 2.82 alpha.

"Point Instance" node is a node that can generate instance of objects very quickly and efficiently. You can have a large numbers of objects using instancing without crashing Blender. With Point Instance, currently you can control the Position, Rotation, Radius / Scale of instances on the fly. And in this video, you will see also we can quickly override the original data of Point Cloud using "Random Attribute" node.

Remember this is still ALPHA version of Blender Geometry Nodes, so things might change again. However, as long you understand the basic concept, then it will be easy to work with different system.

GITHUB:
https://github.com/enzyme69/blendersushi/issues/945