Ah tree shapes much better! Can you do heights according to distance away ie the higher up in landscape the smaller the trees? Something to try...
Also do you know how to vary browns and greens? Formula for Brown is 3 parts red + 2 parts green + 1 part Blue
So really really dark brown is _RGB32(30, 20, 10) probably looks black but
60, 40, 20 might serve plus some randomness of course
and tans and beige is like 255, 128, 64 really light, 200, 100, 50 darker...
Greens browned up by adding red and blue grass is made by adding... well blue of course ;-)) but always way less than amount of green.
Hills would get bluer as recede into background because more air and reflecting more sky like lakes and oceans only more subtle because 0 smooth surfaces.