Specifically, the beta test will kick off on Wednesday March 26th (we have no specific time for you just yet), and in preparation, just about everything the alpha testers have gathered and created will be wiped, to ensure everybody starts at the same point.
That means, if you’re in the alpha test, you’ll be able to keep your character name, your templates and any purchased items (from the marketplace, or your Founder’s Pack goodies).
To get ready for the end of Alpha, we highly recommend that you template any items on your claims that you want to resurrect during Closed Beta. Consider templating things with props, without props, and possibly even re-textured as dirt or something simple so that you can rebuild it easily when you have few resources available.
The other side of this: If you’re not already in the alpha test and want to be in the beta, go register your interest!