Thanks to both of you.

I get the confusion about the black lines on the mountainridges. I'm not sure yet of how to tackle that problem. If I remove them, as you suggested, it will look completely blurry (I'm not home right now so I can't show you). Maybe I should remove the grey shadow layers and just work with lines. That could take care of the trees not matching problem, too.

Thanks for the compliment on the forest! Figuring out that style took a few days.