To me the colours and general shapes of trees are cohesive with the surroundings but given the angle that the view is looking onto the surroundings, the angle you have drawn the trees needs reassessed. The trees look like they are almost falling away from the camera. Take A Link to the Past as an example:
Although the style and shape of the trees are not the same as yours and despite the fact that Link himself is not angled well, you can noticeably see more of the tops of the trees just like you can see almost all of the patches of grass on the ground. While keeping depth of trees can be difficult, it can be done By layering segments of the trees with contrasting colours:
Just my two cents. Hope it helps!