Complex sentence: Director of the Dorschkamp Research Institute for Forestry & Landscape Planning from 1954 until his retirement in 1992, he was responsible for the raising and release of numerous elm hybrid cultivars, notably Columella.
Split into simpler sentences: Director of the Dorschkamp Research Institute for Forestry & Landscape Planning from 1954 until his retirement in 1992. He has been responsible for the raising and release of numerous elm hybrid cultivars, notably Columella.