3 slides to illustrate 3 concepts to my class:
Slide 1: Simple, black and white (pen and ink-like), tree trunk with limbs, perhaps a bit of texture on the bark of the tree. Tree should be the only thing on slide.
Slide 2: Add leaves (green) and color the bark of the tree (brown). Perhaps add the ground/grass.
Slide 3: Add fruit (your choice), a few birds, a bird's nest, a beehive, perhaps a few flowers in the grass under the tree, perhaps a mushroom under the tree. This last slide is supposed to represent the guild that a tree provides (that is, the tree, plus the life it supports, and which supports the tree).