I must admit that I'm feeling a bit uncomfortable [not always a bad thing!] with the slope and all the leaning trees. It might be me only! FWIW, I like the light background with the darker trees… I don't see separation as a problem. I also like the light, sunlit patch of grass at the bottom left of your image.
I agree with the slope being the problem here not the lighting.This kind of off kilter composition can sometimes work depending upon the subject matter e.g. buildings- architecture as a more geometric abstract.
But here my brain sees the composition as totally unnatural and too steep, there is too much tension (trees grow vertical no matter how steep the slope is), and our brains are fighting to make it right as they know it should be ;-) If you at least make slope more gradual by making the large tree at the right side vertical it does help somewhat. ;-)