ctzmy suggestion would be to add more detail to your heightmap. Absolutely flat heightmaps such as yours look unnatural and lifeless. On any section of flat terrain, you should have a feature, such as a runway, road or building. The rest should have a slight slope or some other height adjustment going on.
then, once you have some height changes throughout your map, use ed42 to redo your textures, using a height modifier to make the high sections slightly lighter/darker than the others. This will give your heightmap real depth and it really adds a realistic look :)
:lol: Guess what I was doing last night with Ed42?
One thing that I think detracts from the map is that the terrain seems to be covered with something similar to large coarse crushed beige and bregy gravel almost but I dont have that. Redid terrain with ED42 and it looks better and doesnt have the jaggies anymore but it still looks like not enough trees.