This is essentially what I did with the "Should we keep going" populations.
I splotched out an forest area made of 25% and 75% white areas to signify density. For trees, I left the painted shared as is, and switched up the seeds and spacing for different models.
For the vegetation, I inverted the shader so the areas with less trees has more ground cover/bushes/etc (less light absorbed from tall trees means more light reaches smaller plants).
