SetSky 
        /Material:"GrassHills Skybox"
for (i = 0; i < 50; i++)
{
    x = random(-30, 31)
    z = random(-30, 31)
    s = random(1, 10)
    s = s * 0.1
    AddNatureModel 
            /NatureType:Big Tree
            /Position:{x}, 0, {z}
            /Scale:{s}, {s}, {s}
}