Sometimes you need trees in the background that may be covered by other foreground trees, but still need to be constructed loosely.
I cut a loose shape and add the trunk.
Then I rough cut around the edges, sometimes coming close to the trunk and sometimes not.
I go all the way around the shape.
Then I add a few pieced over the trunk and fuse them.
Group them together and they are ready to quilt in the detail.
Then the actual foreground detailed trees are ready to be constructed.