Lt. Col. Paul Fredin, 56 Civil Engineering Squadron commander, and Chief Master Sgt. Jeffrey Martin, 56th CES superintendent, plant a tree for Arbor Day April 26, 2019, at Luke Air Force Base, Ariz. Arbor Day is recognized as a national holiday, celebrating the importance of trees and plant life within the ecosystem and promotes planting and caring for trees. (U.S. Air Force photo by Airman 1st Class Zoie Cox)