Professor Hans Trass is from one of the newest independent states of the world, namely Estonia. He is a distinguished lichenologist and botanist, having competence in many different field-. He was born in 1928 and studied at Tartu University. His candidate’s thesis – which in the Soviet system actually corresponded to a doctoral thesis in most countries – was completed in 1955, and dealt with the fen flora and vegetation of western Estonia. He had already been the head of the Department of Plant Systematics and Geobotany of the Tartu University for more than ten years when, in 1969, he finished his official Doctor’s thesis, entitled “The analysis of the Estonian lichen flora”. In 1971 he became a Professor, and although he recently retired from his position as a head of the department, he is still continuing his work.
Besides his Ph.D. thesis Hans has published numerous other papers on lichens from 1956 on. Nevertheless, for much of the time lichenology has been just a sideline for him. He was often engaged in studies of vegetation ecology, publishing in 1976, for instance, a major book: Vegetation science: history and contemporary trends of development, originally published in Russian. In 1973 he wrote a major article on vegetation classification in Handbook of Vegetation Science edited by R.H. Whittaker.
He studied the lichen flora of Estonia, but also led expeditions to remote areas of Russia, such as the Murmansk Region, Kamchatka, Sikhote-Alin Range and other areas in the Far East, Lake Baikal and Taymir Peninsula in Siberia, Kazakhstan and the Caucasus Mts. He especially promoted the study of lichens as pollution monitors, e.g. in 1968 with a paper entitled “An index for the utilization of lichen groups to determine air pollution“. He developed his own Index of Poleotolerance (IP) based on lichens, and several students of his are continuing the work, for instance Kristjan Zobel, who completed his Ph.D. thesis under Trass this year. Hans also contributed to the Handbook of the lichens of the USSR by publishing the accounts of three families in it.
In addition, Hans has always kept numerous direct contacts with lichenologists all over the world, also travelling and working abroad, for instance, Canada, Germany, Sweden and Finland. He maintained good relations with Russian and western lichenologists, often acting as a bridge of knowledge between them, to the benefit of lichenology. He was known for his excellent lichen library and to Russian students was regarded as a “western professor”.
To honor his lichenological research, his effective teaching, which has produced numerous lichenologists in Estonia and elsewhere in the former Soviet Union, and for his most useful activities in promoting international cooperation in lichenology, it is appropriate that he receives an Acharius Medal.
– Teuvo Ahti