Using my land as a driveway

What is the name of your state? FL
The property owner behind my land is using my property as his private driveway. About a year ago I purchased undeveloped lakefront land, at that time the neighbor had just bought his land as well. His land had an existing house on it.
The previous owners of the house had a road that crossed thru their property. The new owner blocked the road and put up gates. I am fine with him blocking access to people driving in front of his house.
My problem is he refuses to stop driving over my land. He put trees and other debris to block access from the public road on the other side of his property.
I have sent certified letters explaining that I plan to build and the road is closed. He didn't respond until I put up a gate. Then he called and left a message that it is illegal for me to land lock him and I must wait until he has a way out of his property.
He has been driving around my gate for a couple of weeks now, not even starting to remove the debris that is blocking him in. I plan on fencing my property in and blocking all access. I really don't want him to wake up to go to work one morning and not be able to get out of his property, but I feel like I have no choice.
My question is: Is it legal for me to "landlock" him? Can you think of any other way to resolve this situation?

Based on your post, you are not landlocking him. He is blocking his own access to his property from his other road that he put a gate on.

You have no reason to let this continue. Either a fence or some really big rocks should solve the problem. Or post a no trespassing sign and try to have him arrested the next time he destroys your lawn by driving across it.