Birch Forest Watercolor Painting - Under painting study

I have started a small study based on using under painting in watercolor.  First I sketch a Birch tree forest scene with pencil on a 7×9 inches cold press watercolor paper.  I have choose Burnt Umber as the underpainting color pigment.  Using Burnt Umber in diltued and full strength, I will concentrate in the various tones I get.  This will train my eye to focus just on to the tonal vlaue range of the painting.  The above photo shows the progress I made on this watercolor study.