This looks like a great start.

As for the vegetation: It looks like the grunge brushes you are using have well-defined edges. Softer edges might work better.

Think of it this way, from 2,000 feet up, the individual plants become blurry. Grasses are a sea green with gentle variations.
Bushes and shrubs have a blurry outline because they aren't a solid mass of leaves - they're branches of varying lengths with leaves
and there's space between the leaves. The same applies to trees. And of course some of the leaves are in the shade...

I use GIMP which supports image hoses, so I'll use a brush that has about a dozen variations on a grunge texture
that paint out randomly, each one with a randomly selected shade from a gradient. And each image has varying opacity
throughout the pattern, giving it a variable degree of transparency regardless of the layer's blend mode or opacity.
But I have no idea of how you could achieve a similar effect in Photoshop.