I like it as is. Leave the rock it works, it's texture and shape is convincing and creates a nice step from your tree to the horizon mountain. I'd work on getting that tree to look real. Lower it for a start so there's no gap under the root, or raise the ground around it. Then I'd try and get more variation in you scrub grass. Maybe a few low dry bushes here and there to add a few blobs towards the horizon. But keep it simple. A bit more clumpy perhaps.
The change from reds to haze blue is the colour interest that really works here. Get some more subtle detail in this and its a photo.