It's a bit of an extreme case, but basically if you'd own land and someone else took it over (not by force) and took care of it for a longer period (several years), that someone else could claim ownership and be granted the land.

So if you'd "abandon" your property, someone else could take it over, provided he would take care of it.

The modern equivalent would be, in my opinion, buying houses or apartments and leaving them unoccupied. Outright usucapio would be a bit strong, but I definitely think exponentially higher rates of taxation would make sense.