Today, I’ll do a little advertising for PowerShell script that I found very useful. This script allows you to export a Term Set in a csv file. Very useful to migrate the contents of term store from one environment to another!
You can find this script here: http://gallery.technet.microsoft.com/office/PowerShell-for-SharePoint-a838b5d0/view/Reviews
As a reminder, to import a csv file, just go in the term store, click on the arrow at a group level and click “Import Term Set”.
Hope this helps!