I think the author's method of structuring the story is especially effective for two reasons.

First of all, by using short scenes instead of a tight plot, he allows the reader to experience the material rather than just read it, providing the opportunity for greater involvement in what is happening.  The short scenes also better enable him to define and communicate the points he feels are important.

Secondly, the story is told from the point of view of a young child.  Children learn and form concepts from series of experiences in their lives, which is exactly what the author provides for the reader by the way he has structured the story.  We are able to see the world from Little Tree's perspective, in short scenes presented in chronological order, and, like the child, we are "educated" right along with him.