Thorvald Julius Sørensen
|Born||4 July 1902|
|Died||21 June 1973 70) (aged|
|Alma mater||University of Copenhagen|
|Known for||Flora of the Arctic, Sørensen similarity index|
|Institutions||University of Copenhagen|
Thorvald (Thorwald) Julius Sørensen (4 July 1902 – 21 June 1973) was a Danish botanist and evolutionary biologist.
Sørensen was professor at the Royal Veterinary and Agricultural University 1953–1955 and at the University of Copenhagen 1955–1972. He was director of the Copenhagen Botanical Garden and Botanical Museum during the same period.
Thorvald Sørensen spent the years 1931–1935, based on Ella Island, studying plants in the then little known North-East Greenland. He published the botanical research of the Three-year Expedition to East Greenland.He also published a doctoral thesis on the annual phenological rhythm of the High Arctic plant species, including the pollination of their flowers (1941).
He critically revised the Greenland flora and sorted out taxonomy of a number of difficult taxa, most notably Puccinellia .
He carried out a number of studies in the evolutionary biology of plants, such as Taraxacum , Capsella bursa-pastoris and Ranunculus .
He developed a quotient of similarity in species composition between plant communities—the still much-used Sørensen similarity index. He illustrated its use on a data set collected in Danish grassland by Johannes Grøntved (1882-1956), who used the quantitative method to sample vegetation developed by Christen C. Raunkiær (1860–1938).
The Arctic campion species Silene sorensenis and Th. Sørensen Land in Greenland were named in his honour.
Johannes Eugenius Bülow Warming, known as Eugen Warming, was a Danish botanist and a main founding figure of the scientific discipline of ecology. Warming wrote the first textbook (1895) on plant ecology, taught the first university course in ecology and gave the concept its meaning and content. “If one individual can be singled out to be honoured as the founder of ecology, Warming should gain precedence”.
Christen Christensen Raunkiær was a Danish botanist, who was a pioneer of plant ecology. He is mainly remembered for his scheme of plant strategies to survive an unfavourable season and his demonstration that the relative abundance of strategies in floras largely corresponded to the Earth's climatic zones. This scheme, the Raunkiær system, is still widely used today and may be seen as a precursor of modern plant strategy schemes, e.g. J. Philip Grime's CSR system.
Anders Sandøe Ørsted, also written as Anders Sandoe Oersted or Anders Sandö Örsted was a Danish botanist, mycologist, zoologist and marine biologist. He was the nephew of physicist H.C. Ørsted and of politician Anders Sandøe Ørsted.
Johannes Iversen was a Danish palaeoecologist and plant ecologist.
Tyge Wittrock Böcher was a Danish botanist, evolutionary biologist, plant ecologist and phytogeographer.
Carl Emil Hansen Ostenfeld was a Danish systematic botanist. He graduated from the University of Copenhagen under professor Eugenius Warming. He was a keeper at the Botanical Museum 1900-1918, when he became professor of botany at the Royal Veterinary and Agricultural University. In 1923, by the early retirement of Raunkiær's, Ostenfeld became professor of botany at the University of Copenhagen and director of the Copenhagen Botanical Garden, both positions held until his death in 1931. He was a member of the Royal Danish Academy of Sciences and Letters and served on the board of directors of the Carlsberg Foundation.
Ove Vilhelm Paulsen was a Danish botanist.
Olaf Hagerup was a Danish botanist. He studied botany at the University of Copenhagen from 1911 under the professors Eugenius Warming, Christen C. Raunkiær, L. Kolderup Rosenvinge og W. Johannsen. He took his Ph.D. from the same university in 1930. From 1934 to 1960, he was superintendent at the Botanical Museum of the University of Copenhagen.
Knud Jessen was a Danish botanist and quaternary geologist. He was state geologist 1917–1931. In 1931, he succeeded C.H. Ostenfeld as professor of botany at the University of Copenhagen and director of the Copenhagen Botanical Garden, a position he held until his retirement in 1955. His scientific works mainly concern vegetation history during the Eemian interglacial, the late glacial period of the Wisconsin glaciation and in the Holocene investigated using pollen analysis.
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Gunnar Nygaard was a Danish phycologist, and a leading authority on the ecology and taxonomy of Danish phytoplankton. Nygaard completed his Masters at University of Copenhagen, initially working at the Freshwater Biological Laboratory in Hillerød as a research stipendiary. From 1933 until his retirement in 1972 he was employed as a lecturer in the Danish grammar school system. Thereafter, he was provided an office at the Freshwater Biological Laboratory to facilitate his work. In recognition of his scientific contributions, the University of Copenhagen awarded him the degree dr. scient. honoris causa.
Jens Arnold Diderich Jensen was a Danish naval officer and Arctic explorer.
Jens Wilhelm August Lind was a Danish apothecary, botanist and mycologist. He was a pupil of Emil Rostrup and published a full account of all fungi collected in Denmark by Rostrup. These were mainly microfungi, such as plant pathogens. He also wrote accounts on microfungi from Greenland and elsewhere, mainly based on collections made by other persons on expeditions, e.g. Gjøa expedition and the Second Thule Expedition. Combining his pharmaceutical and mycological knowledge, he was early in experimenting on chemical control of plant pathogens and recommending it to other practitioners. He also - together with Knud Jessen - wrote an account on the immigration history of weeds to Denmark.
Paul Emil Elliot Gelting was a Danish ecologist, botanist and lichenologist. He was associate professor at the University of Copenhagen and particularly active in Greenland.
Jenny Hempel was a Danish plant physiology pioneer. In 1916, she was the first Danish woman to receive a doctoral degree in a botanical discipline – and until 1956 the only. She discovered the diurnal fluctuations in cell sap acidity in succulent plants, with are now known to be linked with the CAM photosynthetic pathway.
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Allium micranthum is a plant species native to Pakistan and Afghanistan. It is a perennial herb with an egg-shaped bulb about 10 mm across. Scape is up to 40 cm tall. Leaves are narrowly linear, up to 3 mm across. Umbels are almost spherical with many flowers crowded together. Tepals are tiny, no more than 3 mm long, purple.