The Balance Between Showing and Telling

Show, don't tell.
It is an old truism for authors that really works when applied, except when it doesn't of course. The author must strive to engage the reader and a long, dull description is not a good way to do that. 
The forest was beautiful. 
VS
Towering conifers dimmed the noonday sun and hid a dozen micro-climes in the tangle of their roots.