More tiny leaves on the surface which, while actually anchoring the sandwich together at the top, will add some interest in the empty spaces.
I took a risk and "drew" some background trees. I wanted them indistinct and I couldn't get that with thread or a strand of wool. Using an ordinary coloured pencil and a ruler I drew about 8 lines in a dusty gold, over the netting and onto the fabric. It gave me the look I wanted. Whether or not it will stand up to all of the manipulation this cloth will get before its finished, time will tell. But I know that if I need to touch it up at the end, I can.
Over all this I placed some blobs of organza in 3 greens. And then some grey trunks. It works.
What's at the back of my mind, though, is when and how to transition to cloth for the foliage.