The tree I am using is the speedtree “broadleaf_mobile” sample tree.
After I build lightmap with high quality:
As you can see it looks terrible. Here is my UV unwrap:
Any help is appreciated. Thanks 
Have a look at this guide for basic lighting issues, specifically take a look at the Static Lighting sections: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
I couldn’t find anything in that article that would help my problem, any other suggestions?