Amyan Macfadyen was born in the Weald of Kent on 11 December 1920, the son of a colonial administrator who also served as a Liberal MP.
He studied at Dauntsey’s School in Wiltshire and Balliol College, Oxford, although his education was interrupted by war service in the Royal Electrical and Mechanical Engineers. He remained in Oxford to begin his career at the Bureau of Animal Population (1947-56).
From Oxford, Professor Macfadyen moved to Swansea University as lecturer in zoology, and was later promoted to reader. Already a major authority in his field, he distilled his insights into a definitive textbook, Animal Ecology: Aims and Methods (1957).
In 1965, he was appointed guest professor at the Jordbundbiologisk Institute, part of Aarhus University in Denmark. He published widely on soil ecology, particularly energy flows and metabolism in soil ecosystems, and discovered a number of new species of invertebrates. Other writings explored the fundamental philosophical assumptions underlying environmental thinking.
In 1967, Professor Macfadyen returned to the UK for the rest of his career as one of two founding professors of biology at the New University of Ulster (now Ulster University) in Coleraine, Northern Ireland.
He soon proved an energetic educational reformer, adopting an innovative modular structure for degrees and courses in both ecology and human ecology. He was later elected dean and pro vice-chancellor and provided crucial support for his former student Gerry McKenna (later vice-chancellor of NUU) in introducing a programme in biomedical sciences.
“Amyan was loved and hugely respected by a generation of biologists, myself included, who were inspired by his knowledge and enthusiasm for biology and the protection and sustainability of the natural environment,” recalled Professor McKenna. “His intellectual and scientific gifts were underpinned by unwavering moral integrity and generosity of spirit, qualities which will continue to influence all who knew him well.”
Although he retired from NUU in 1986, Professor Macfadyen continued to develop a superb three-acre garden on the banks of the River Bann, which was open to anyone interested in the vast range of species that he and his wife Ursula had assembled there. He also took part in scientific expeditions to the Falklands and Tanzania.
Even after he moved to Sheffield in 2006, at the age of 86, he remained committed to environmental causes, winning a South Yorkshire Care4Air award in his nineties.
Professor Macfadyen died on 3 October and is survived by a daughter, three sons and seven grandchildren.