I have been struggling to get the shadows from trees etc to match on my character. To start with I used directional light and tried to build tree branches to get there right shadow. This was very hard to have good control on.
On my second attempt I used one spotlight on far distance to get the feel of sunshine. On the color I mapped a tree alpha picture. Did some tweaking on this, and ended with shadow looking good. Not exactly right but hopefully looks good in the end.