I'm forced to admit: when I'm right I'm right.
I compared the before and after, swapping back anf forth between two different other windows, and not only does the darker cave look more recessive, it also looks "better". The darker color off-sets the large area of lighter green which evens out the whole composition's balance between the dark sky and the lighter ground. That's more pleasing to the eye, I think.
It gives me ideas for a game...
I can see those blocky little dudes coming ashore from that lake, (except that one who didn't make it, obviously) and then trying not to fall in those holes as they make their way in-land. It's made all the more difficult by the craggy cliff that juts out under the tree. Trying to jump up there just results in them sliding down dangerously close to the holes. Maybe they teamed up to get that little red fellow passed the cliff, but he was the only one they could manage. The others tried, but two fell in the holes, while the last one was left alone and hopeless, so he joined his friends under the ground. Ironically, he was the first to be eaten. But after their brave sacrifice, how far will their little red friend be able to make it in this strange and inhospitable land? Not much farther than the first tree he finds himself crowded by more strange ceatures. His luck might have run out, unless they don't mean to harm him after all... If not, they might be his only hope in getting over that tall standing stone on the hill. What could be on the other side?