Referencing individual cells of a tilemap and changing texture

I have a tilemap and am trying to proceduraly generate islands on it by changing the texture of the tiles and marking it as land ( I want to do this without texture atlas for now). How do you change the texture of an individual tile and how do you mark the tile to distinguish it from other tiles within map as land . I have tried to do this but for some reason even though I reference an individual tile all tiles are changing textures.

private static TiledMapTileLayer baseLayer;
private static TextureRegion landTextureReg;
private static Texture landTexture;
private static TiledMapTile landTile;

public static TiledMap generateMap(){
landTexture = new Texture(Gdx.files.internal("hex_land_trans.png"));
landTextureReg = new TextureRegion(landTexture);
TiledMap map = new TmxMapLoader().load("ocean_hex_map.tmx");
baseLayer = (TiledMapTileLayer)map.getLayers().get(0);
baseLayer.getCell(1, 1).getTile().setTextureRegion(landTextureReg);
return map;
}