Dear IUFRO colleagues it is with great sadness we have to inform you that Prof. William (Bill) J. Manning (born on June 13, 1941), professor emeritus at the University of Massachusetts at Amherst, USA, passed away on March 4th, 2023 in Boston, following a 6-month illness. He received his B.S. in Horticulture from Michigan State University, and M.S. in Plant Pathology and Ph.D. in Biology from University of Delaware. Bill was a widely known and well-respected scientist who pioneered research on the impacts of air pollution on plants. His research focused on responses of plants to ozone and how ozone and other air pollutants affect plants growing in forest and urban environments. He promoted use of plants as bioindicators of various air pollutants, summarized that idea in a widely-read book “Biomonitoring of Air Pollution with Plants”. He worked for more than 10 years in Central and Eastern Europe surveying forests of the Carpathian Mountain for in situ bioindicators of ambient ozone. His long-term studies on loblolly pine (Pinus taeda), bean cultivars, and clover clones by making foliar applications of antioxidants (ethylenediurea) helped to clarify the complex picture of sensitivity and tolerance of plants to ozone. For over 30 years Prof. Manning was an Editor-in-Chief of the prestigious Environmental Pollution journal. Scientists specializing in air pollution and climate change impacts on plant ecosystems recognize Bill’s enormous contribution to the development of this subject. He was also an outstanding, generous, inspiring mentor for numerous young scientists all over the world. He welcomed Ph.D. students and postdoctoral scientists into his laboratory, and also mentored students met at various domestic and international conferences. Although he was not an IUFRO officeholder, he was a very good friend of IUFRO and actively participated in the activities of the RG 8.04 (formerly 7.01) on air pollution and climate change impacts on forest ecosystems. For instance, he gave an invited speech on this topic at the IUFRO 125th anniversary in 2017. When he retired, the RG8.04 established ‘The Bill Manning Award’ for the best poster presentation at its biennial conferences, as a recognition of Bill’s mentoring role in forestry and environmental sciences. During his retirement Bill continued to be scientifically very active. In 2020 he published his last book entitled ‘Trees and Global Warming: The Role of Forests in Cooling and Warming the Atmosphere’. Professor W. J. Manning was sincerely admired and respected by his peers for his integrity, passion, vision and love for science. The scientific community has lost a prominent and outstandingly creative colleague. We mourn Bill’s loss not only as a scientist, but particularly as a gentleman colleague of a cheerful demeanor and with an exceptional sense of humor. His loss is immense and he will be fondly remembered by many colleagues around the world. We will miss him as a good friend and companion of many experiments, travels and scientific expeditions. We offer our sincerest condolences to his wife Arlene, and sons Stephen and Michael with their families. Elena Paoletti and Andrzej Bytnerowicz on behalf of IUFRO colleagues and friends Attached is a picture of the three of us in one of many happy moments together – at the IUFRO World Congress in South Korea in 2010 (from right to left – Bill Manning, Elena Paoletti and Andrzej Bytnerowicz) -- *Institute of Research on Terrestrial Ecosystems (IRET)* *National Research Council* * (CNR) * Via Madonna del Piano 10, Sesto Fiorentino (Florence), Italy Tel: +393298061717 https://www.cnr.it/people/elena.paoletti