Hey there, welcome, from another new comer
I found myself starting something similar to this
- Personally I would add little variations to each tree, something to make them less uniform.
a lot of the shading lines up, which makes this a slave to the grid. Generally you want to break the grid.
the light source is coming from the right, therefore maybe some of the trees on the left are slightly less illuminated. If you do this subtly, I think it might add something,
if nothing else, it will add some variation, but I would be conservative.
- maybe going a bit deeper with the brown on some of the trunks, to add a third layer of depth to the piece.
- maybe add some darker shrubs, grass and foliage behind the first layer of trees to give the scene more life. diversify the colors of the flowers and try to add maybe a few different types of shrubs.
also, maybe a very dark green, almost black for the background color behind the trees.
Just my two cents, hope it helps.