Very nice!!

One thing that jumped out at me (though, it's not horrible) is the ground texture style seems to clash a bit with the hand drawn look everything else.

One other suggestion (though I don't know how easy/hard/possible to do in Xara) is to add some more depth to your trees by adding some shading "inside" the tree shape. I suspect that this might just be very time consuming, but if it is not, it really will make the whole pop I think.