The painted parts done before the build were then brought out
and assembled as per the destruction sheet.
The trees were in the kit.
The trunks just taken off the sprue and given a minor cleanup, glued on and painted.

The greenery on the trunks was from a small lump of green foam in the kit.
As per the destructions, rip into small bits and glue on.
Done in short order and they do look the part.