Trees can be used as elements of elevation contrasts and punctuation marks, or maybe more precisely, as exclamation points.
The trees here call attention to the taller space yet also create awareness of the empty space, providing a sense of openness.
Or, as visual corridors:
Or, as if on a pedestal, the center of interest:
Or, as an addition of texture, contrast, counterpoint, harmony, or even a little bit of agreeable dissonance:
A foreground to a visual backdrop:
Or, as a matrix for screening: