John Lander Harper, one of the leading ecologists of the 20th century, has died.

He was born on May 1925 and educated at Lawrence Sheriff School, Rugby. He studied for a first degree in botany at the University of Oxford and stayed on for an MA, an MPhil and the first nine years of his research career. After a year in the US as a Rockefeller Foundation Fellow at the University of California, Davis, in 1960 he moved to the University College of North Wales, Bangor, as professor of agricultural botany.

He remained at Bangor until his retirement in 1982, serving from 1967 as head of the highly influential School of Plant Biology. His post-retirement roles included a visiting professorship at the University of Exeter from 1998.

His central achievement was establishing the field of plant population ecology, rooted in Charles Darwin's crucial insight into the role of individual differences in evolution by natural selection. Major honours followed.

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Professor Harper was president of the British Ecological Society (BES) from 1966 to 1968, and his presidential address, "A Darwinian Approach to Plant Ecology", was immediately acclaimed as a classic overview.

His eminence was also recognised in the BES' John L. Harper Young Investigator Award, given annually for the best paper by a young researcher published in the Journal of Ecology. As well as producing more than 130 scientific papers, Professor Harper wrote a monumental book on The Population Biology of Plants, published in 1977.

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He was elected fellow of the Royal Society in 1978 and awarded the society's prestigious Darwin Medal in 1990, a year after being appointed Commander of the Order of the British Empire. He was also co-author, with Michael Begon and Colin Townsend, of two highly successful textbooks: Ecology: From Individuals to Ecosystems (1986), now in its fourth edition; and Essentials of Ecology (2000).

Miguel Franco, lecturer in ecology at the University of Plymouth, remembers a man of "tremendous scientific insight" who rejected the common "holistic" view of ecology and "was proud to call himself a reductionist. In order to develop a scientific understanding of the cause-effect relationships in complex systems, it was necessary to decompose them into smaller interacting components."

He was also an inspiration to several generations of scientists. "His quick mind and wit immediately endeared him to his audience. His lectures were hugely popular. His advice on scientific matters could easily be read as parables for ethical conduct in both academic and private life."

Professor Harper died from complications related to leukaemia and emphysema on 22 March. He is survived by his wife, Borgny, three children and seven grandchildren.

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matthew.reisz@tsleducation.com.