Oliver Gilbert

Oliver Gilbert was, in his own words, a lichen hunter. His pioneering work on these humble plants as indicators of air pollution and on the lichen flora of remote and unexpected places helped create a healthy climate of field study and exploration for a whole generation of apprentice lichenologists. He was also one of the leading urban ecologists who studied and promoted the hidden wildlife jungle in and around towns and cities.

Oliver Lathe Gilbert, ecologist and lichenologist: born Lancaster 7 September 1936; Lecturer in Landscape Ecology, Sheffield University 1968-86, Reader 1986-93, part-time tutor 1993-2000; married 1969 Daphne Broughton (three daughters; marriage dissolved); died Sheffield 15 May 2005.

Oliver Gilbert was, in his own words, a lichen hunter. His pioneering work on these humble plants as indicators of air pollution and on the lichen flora of remote and unexpected places helped create a healthy climate of field study and exploration for a whole generation of apprentice lichenologists. He was also one of the leading urban ecologists who studied and promoted the hidden wildlife jungle in and around towns and cities.

When Gilbert first became interested in lichens in the 1960s, little indeed was known about the ecology and distribution of these hardy and primitive plants. Those able to become familiar with the 2,000 or so British species could expect to make new county records almost daily and even discover new species. Gilbert's personal contribution to lichen study was to imbue it with a boyish spirit of adventure. Like the Victorian plant collectors, he was willing to travel far, camp out on remote mountains and islands, and scale sheer cliff faces in pursuit of rare lichens.

In addition he had an exceptional "ecological eye" for spotting likely places and tiny plants in the field. In his book The Lichen Hunters (2004), he recalled "the joys of companionship with kindred spirits and the charm of out-of-season hotels, where the meals are small and hot water scarce". Gilbert and his band probably came as close as any in modern times to the spirit of the bygone plant-hunters. Thanks to their work, carried out over three decades, the British lichen flora is now among the best studied and recorded in the world.

Oliver and his twin brother Christopher were born in Lancaster in 1936, the sons of Frank Gilbert, managing director of Durham Chemicals, and Ruth Ainsworth, a writer of children's stories. Shortly afterwards, the family moved to London, where Oliver attended Harpenden School. He recalled becoming enthralled with plants at the age of three. By his late teens he had botanised extensively in Britain and the Alps, where he combined the search for alpine flowers with his other passion, rock climbing.

At Exeter University, where he read Botany, Oliver Gilbert flirted with mosses and liverworts, and afterwards studied fungal diseases of plants at Imperial College, London. He first became seriously interested in lichens after meeting Arthur Wade, who ran a week-long annual course in lichenology at Malham Tarn Field Centre in Yorkshire, where Gilbert was deputy warden.

Interested in the apparent sensitivity of lichens to air pollution, particularly sulphur dioxide from coal-fired power stations, Gilbert joined the staff of the Botany Department at Newcastle University in 1964 and registered for a PhD. His work, published in 1968 as Biological Indicators of Air Pollution, which involved field recording of lichens and mosses, became one of the classic studies of plants as biological indicators. It showed how the naturally rich flora of pure unpolluted air became progressively denuded as one approached industrial centres. Gilbert was awarded a PhD in 1970. His work brought some welcome publicity for lichens, and contributed to the wider environmental debate.

In 1970, Gilbert organised a lichen survey of the Cheviots, work which led to the publication of A Lichen Flora of Northumberland in 1988. His many later expeditions with the British Lichen Society explored promising islands like St Kilda, North Rona and Coll, as well as remote and lichenologically unknown Scottish mountains like Foinaven and Ben Alder.

Nearer to home he became an authority on aquatic lichens, and the lichens of limestone and the serpentine of the Lizard in Cornwall. In the field, and in the company of like-minded adepts such as Brian Coppins, Alan Fryday and Vince Giavarini, Gilbert was in his element. As he recalled, "You go to look for lichens, and you find in addition familiarity, beauty, companionship, laughter and the warmth of friends."

From 1979, Gilbert took over the editorship of the British Lichen Society's twice-yearly Bulletin. A fluent writer, Gilbert wrote much of it himself, introducing a readable "Country Diary" and regular items on "neglected habitats". His scientific papers in The Lichenologist were exceptionally readable, being based on direct observation and undisguised pleasure in his subject. Like many amateur lichen hunters, Gilbert regretted the increasingly technical and unapproachable nature of scientific papers on lichens. The subject, he thought, "is running away from us". He became famous for finding rare lichens in unexpected places, among them concrete airfield runways, old mine-workings and the "drip-zone" under motorway crash barriers. In 1997, Gilbert was made an honorary member of the British Lichen Society, and, a rare honour, in 2004 received its Ursula Duncan Award in recognition of his outstanding contribution to the study of lichens in Britain.

In 1968 Gilbert became Lecturer, later Reader, in Landscape Ecology at Sheffield University, where he remained until his retirement in 1993, then continuing to teach part-time until 2000. He taught his students, many of whom became practising landscape architects, to respect the genius loci of a place with its natural soil and vegetation. Characteristically, he believed that one could learn at least as much from failures as successes, especially in the frequent instances where landscape plans came to grief because they had neglected simple ecological principles.

Along the way he became an authority on the ecology of urban wildlife, helping Sheffield to become the best-studied urban jungle in Britain after London. Among his discoveries was Britain's only forest of wild figs, growing by water formerly warmed by Sheffield's Bessemer steel furnaces. He became author of two influential textbooks, The Ecology of Urban Habitats (1989) and Habitat Creation and Repair (1998, written with Penny Anderson). Both books drew on a wealth of practical experience both in Britain and in North America and the Netherlands, where habitat creation has become an art form.

After retirement, Gilbert wrote a much-praised book, Lichens (2000), for the Collins New Naturalist series, notable for its range of photographs taken by the author as much as its graceful and readable style. This was followed by his last book, The Lichen Hunters, a record of the explorations of Gilbert and his fellow lichenologists which surely passes the key test of a travel book - any reader with the same love of the natural world will wish they were there.

Since the mid-Nineties, Gilbert had suffered from kidney disease which required weekly dialysis. Characteristically, he took the growing inconvenience in his stride and rarely mentioned it. He was in demand as a lively, entertaining speaker, and as a life-enhancing presence at any field meeting.

Had he lived, his work would have been crowned by a new lichen flora of the British Isles, of which Gilbert was overall editor and which was at an advanced stage at the time of his death.

Peter Marren