Is it trees?
Actually, trees and detail brick generation has already been added.
Speaking of which:
toggleable, dynamic streams and waterfalls have been added! Floating brick support (that prevents issues with removing bricks on floating terrain) has also been included. For streams, you can set their color, set the distance they travel on level surfaces before stopping, toggle their collision and set whether they destroy detail bricks in their path. Streams also stop generating when they collide with water bricks or with the water level set in the enviroment settings GUI. If necessary, you can also stop streams from generating mid-routine by disabling them.
I'm currently uploading another mod dev update video, so I'll update the topic's description once it's up.