Here's a quick exampleof how I'd do it.

Cobblestone texture made in Filter Forge.  Used the bump map to create an alpha texture (selecting the colour range between the stones, filling the selection and backfilling in black)

Applied the cobble texture and bump to a flat plane, added ecosystem (used Carex as wabe suggested) and used the alpha I made as a distrubiution map.

As the meerkat says....' simple ' 

Gill