Robert Courts joined forces with conservationists to mark the Queen's lifetime service to the Commonwealth.
Mr Courts helped volunteers at the Wychwood Project, based in Witney, to plant five trees in Foxburrow Wood, near Witney.
Mr Courts said: “We are immensely fortunate to have the Wychwood Forest and other stunning woodlands on our doorstep and I hope these trees will act as a symbol of West Oxfordshire’s commitment to protecting and enhancing these vital habitats.”