Ah yes, that's because the "forests" in my map are actually the "hills" in the tutorial: see Steps 10 and 23-30 for details on how to do this. Also, as Ascension pointed out to me, my forests were not quite dark enough, so I added an extra "Hill Color" layer (with the "Hill Outline" layer mask attached). I chose a dark green color for this layer (274204), set the Opacity of the layer to 65%, and set the Layer Mode to "Soft Light." You may want to play with these settings a bit to see what works best for your map.

Cheers,

- Arsheesh