Hey dude! i really like this kind of art, simply, clean and still with a great meaning.
i like how u used the colors on this image, your sources were well made. The chop on tree is nicely done and the finish is very good.
The only additional (for me) that you could have done is a little bit of shadown is the far horizon... i this the backgroud would merge sky and sea with darkest tones...
well, this not a negative critique, but you could try putting more shadow ym pre bottom of tree (only suggestion).
congrats on your job and keep it up!