I've been trying to identify these trees since we moved up here and they may be Yellow Birch. They are /every/ bloody where up here. I have been really enjoying this thread in the hope that maybe these can be utilized as bonsai. I think I'll try. I have a lot of smaller stock growing along eroded slopes on the mountain, seedlings and possible yamadori all over our fifty+ acres up here. Because I'm not used to birch I initially thought that these were cherries until I tried to place the species by bark identification. Shame I didn't photograph the leaves last season when we moved up here but spring is creeping in and I'll soon have the chance. If anyone doesn't think this is a Yellow Birch, by all means chime in. It'll help when they are in leaf.
Your birch is lovely! I am enjoying the updates and look forward to seeing more.