Simple Kevin,
go outside and take a look.
Healthy trees often kill off the branches on the interior- not enough sunlight.
So what about negative spaces?
I will ask you the same question I asked a member here from Taiwan.
No Penjing masters near you to go and study with or tree designs to
look at ?
I leave this image below,. look carefully [ camera has limits, only one eye ] are
there any branches in the interior of the tree, or is every branch to the
exterior forming the canopy.
Often the Chinese, have small artificial trees in bonsai pots for sale.
Pick up [ just lift up, not purchase] a few and look at them, turn them around.
See how a few branches, placed correctly give the illusion of high density.
Hope this helps.
Anthony
All branchlets are on the exterior, interior is empty.