In the last few days I have been messing with SH5 vegetation GR2, in an attempt to achieve something similar to what echolot has done with his excellent
Small Trees SH5 mod, but without altering tree textures.
The following image shows the results of my tests (click to enarge, but beware large size):
In short, I have scaled stock tree meshes to the following factors: 200, 150, 75, 50, 25 and 12.5%. As you can see, at bigger factors onscreen tree sizes are more or less proportional to mesh sizes. Remember that the game randomizes a bit tree rendering sizes, so don't expect for an exact proportionality.
On the other hand, comparing the screenie for stock tree sizes with the ones featuring 75% and 50% reduced trees, you will notice that only tallest trees (the spruces), having bigger meshes than the rest, seem to be affected by the reduction. Furthermore, bigger mesh reduction factors (25% and 12.5%), don't seem to affect significantly rendered tree sizes.
Concluding, I think that there is a minimum tree rendering size which cannot trespassed. Trees whose mesh is smaller than this limit, are assigned a standard size value when rendered in game. This standard size is automatically randomized by the game, but cannot be altered by further reducing the meshes.
