Hi!
I don´t know if you already tried to make trees of the flowers from the Meadow Sweet?
I use this method for the "bulk of the trees" leaving time to put more effort into a few of the trees closest to the Viewer, which needs to stand out.
The trees looks like this when made as a pine tree, but it´s absolutely possible to also make Birch and Aspen of the Meadow sweet too.
I made a video tutorial explaining how the flowers are turned into trees.