A test of the forest against the deciduous background reveals that it needs more filler.
And we have filler! I got some sprays of plastic leaves, small enough to pass for young 1:6 scale trees, at the craft store today, as well as some other supplies. I mounted them in the usual moss-covered bases made of cured polymer clay painted brown.
Phew! Finally done. I am glad that I used actual sticks and twigs for realism.