It seems to be a theme throughout what I have seen in this challenge. A lot of the scenes are really hard to expose for properly with large bright areas and large dark areas. From your composition your focus is the trees and vegetation in the foreground, yet the proper exposure was given to the mountains in the background. Really tough call here because to properly expose the trees, the sky would get blown out pretty badly. The only solution that comes to mind is using a graduated ND filter (preferably) or perhaps a circular polarizer. A graduated ND filter would darken the sky while leaving the bottom nicely exposed.