Nathaniel,
Added to the pastel background you have a rainbow arc too. The tree appears very dimensional the way you have photographed it. I wish we could see more of that special tree.
Yes, these pastel's provide a far different milieu than blacks. The signals for depth come from progressive levels of density of water vapor or pollutants in the air so one gets deepening layers of mist and muted colors moving towards blue.
Here black would be too severe and would destroy the gentle harmony of the scenes. Black is a major intervention to an image however it's obtained. We do not usually see anything but the moon and stars against black backgrounds or the eyes of wolves lit by a night sky!
That, for now is about all I can say, although I'll return to the thread when I have something more substantial to add.
Asher