Imported from support site: https://support.keenswh.com/medievalengineers/topic/tree-branches-of-death

When cutting trees into logs after felling them, the branches that pop off when you get to the upper end of the tree tend to get their cut off end stuck into the ground. Then the branches go all kraken and start flailing around until they launch themselves at often lethal velocity off into the distance never to be seen again. If you are struck by the flailing or flying branch you usually die.