Very interesting subject captured with nice detail. A lower point of view (kneel on the hot sand!) would have avoided the left side getting lost in the horizon. I think it would work better in straight black and white, or at least a less saturated color.
I like the tonal range you used with this shot - it gives the solitary feel one would experience being out there in the middle of summer. (I know from experience!) :-)
This is really beautiful. Doing it in this coloring was perfect for the theme of the picture. I need to remember this one instead of b&w when I shoot this type.
Interesting duotone. I like this image, but would prefer a stronger emphasis on the tree, as the background elements are not as important in the composition. Not sure how this could be accomplished, maybe a wider aperture or some dodging/burning in post.