Could be protecting plants from the January snows. They also do this to capture "bugs" that want to set up housekeeping. The captured can just be tossed away. No, I don't know what is under there.
Grounds of Ninomaru Palace, Kyoto, Japan 2009
"Take time to wonder as through this world you wander. Never hurry by an open door, for we live in a universe full of miracles galore......"