What kind of tree is this?

I live in Sonoma County, in Northern California and want to know what kind of tree this is. I don't believe the leaves fall much or at all in the winter time. I have not see this anywhere else in my city so don't think it is a native tree.

thanks for your help

 

I'm sure it's non-native. Unfortunately, the leaves aren't much of a giveaway. The smooth bark makes me wonder about Ailanthus.

 

Has the same reddish new growth, too.