In your backyard, you found a woodpecker in search of insects on your favorite oak tree. You discovered that the woodpecker had created a deep groove into the tree bark around the entire circumference of the tree. To protect the tree, you placed a wire mesh around the trunk to repel the woodpecker. The figures below show the tree swathed in mesh and a cross-section of a tree trunk. A few months later the oak tree died. What was the first event that occurred in this tree’s death due to the injury caused by woodpecker?