Sometimes a tree near a home becomes dangerous -- due to disease, or risk of falling on the home during a storm.  Instead of simply cutting it down, it is more environmentally friendly to make it into a habitat tree.  You can see a habitat tree on the right side of this picture, it is about 25' tall and would not damage the house if it fell because the top has been removed.  It mimics what happens in a natural forest when trees snap, and it will provide habitat for wood peckers, squirrels and other small animals.