It’s Tough To Be A Bug and The Tree of Life Trail have been closed while Disney’s construction crews try to determine what caused one of the smaller branches to fall from the tree last night. Some people believe it has been caused by moisture seeping into cracks worsened by the extreme thunderstorm that occurred Saturday night.
Here’s the official Q & A on the matter:

Q.  I heard one of the branches from the Tree of Life fell.  Is this why the area is closed to Guests?
Yes, a small branch (weighing approximately five pounds) fell to the ground, away from Guests and Cast.  In an abundance of caution, we are closing some experiences in the immediate vicinity of the Tree of Life as we further inspect it and complete any necessary maintenance.

Q.  What caused the branch to fall?  Was it weather related?
We are still reviewing the situation.

Q.  What exactly will be closed while we inspect The Tree of Life?
The trails around the Tree of Life will be temporarily closed, as well as the “It’s Tough to be a Bug” attraction and the Kid’s Discovery Club location.

Q. When will the experiences around the Tree of Life reopen?
At this time we do not have a reopening date.