forest goop
If memory serves me right...I recall reading about some sort of forest floor scenery goop that was a mix of blended leaves, white glue, some sort of anti-mold agent since the stuff took so long to set up, and sculptamold...I think. Anyway, this round-robin group of modelers did a series of articles in MR on making deciduous trees and one was on planting. They spread this goop around first, then planted from the ground up; fallen branches, smaller bushes, small trees, trunks, then finally trees with tops. In the end the goop dried, holding all together and making a very realistic looking forest floor. For a conifer forest it will have a somewhat different look, but perhaps pine needles can be ground instead of leaves to produce a different look?
BTW, I like the vibrant green.
Galen