There are two types of trees. There are the groves and the stand-alone trees. I had my slider at about 1.2 miles range and the groves are fine, but I literally cannot see the stand-alone trees until I'm about to hit them. I've tried extending the range slider to full, and the object size slider out more and the other slider as well, but these stand alone trees still refuse to display themselves any further out (and thy like to populate the ends of runways, making landings difficult especially when in a bomber or when damaged).
Bug: The stand-alone trees are not linked to the video settings sliders, as they really really need to be.