This Dynamo script that i made, will place trees in a specific area
(i am not a Dynamo expert so the script can probably be optimized or shortened)
Draw a spline, this spline does not need to be closed
Open the script and select the spline.
the seed you probably don't need to adjust. Only if you have a very large area.
The distance between trees, determines the density of your trees.
Then you can select what kind of trees you want placed.
there are two items that need some attention. Autumn are all the trees in there autumn coat.
Ground coverage will place all bushes and small trees below the small trees, The ground coverage will have a smaller distance between them then the trees, it is set to one third.
Then just run the script and see your forest. It is not possible to scale the trees, but they are rotated
If you have adjustments to the script please post them here.