Thorvald Sørensen
Encyclopedia
Thorvald Julius Sørensen (1902–1973) was a Danish
botanist and evolutionary biologist.
Sørensen was professor at the Royal Veterinary and Agricultural College
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 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
, who used Raunkiær's
quantitative method to sample vegetation.
Example of plant name he published:
The Arctic campion
species Silene sorensensis
was named to his honour.
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
botanist and evolutionary biologist.
Sørensen was professor at the Royal Veterinary and Agricultural College
University of Copenhagen Faculty of Life Sciences
The faculty previously known as the Royal Veterinary and Agricultural University is located in Frederiksberg, Denmark and was established in 1856. As of 1 January 2007, the University merged with the University of Copenhagen...
1953-1955 and at the University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...
1955-1972. He was director of the Copenhagen Botanical Garden and Botanical Museum
Copenhagen University Botanical Museum
The Botanical Museum in Copenhagen originated as a part of the Copenhagen Botanical Garden, which was established in 1600. It was later separated as an independent institutiuon...
during the same period.
Thorvald Sørensen spent the years 1931-1935, based on Ella Island
Ella Island
Ella Island, or Ella Ø, is an island in eastern Greenland, at the mouth of Kempe Fjord in the northern end of King Oscar Fjord. The island is within Northeast Greenland National Park. It was named by A.G...
, studying plants in the then little known North-East Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. He published a doctoral thesis on the annual phenological
Phenology
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...
rhythm of the High Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
plant species, including the pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
of their flowers (1941).
He critically revised the Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
flora and sorted out taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of a number of difficult taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
, most notably Puccinellia
Puccinellia
Puccinellia is a genus of grasses which are known as alkali grass. These grasses grow in wet environments, often in saline or alkaline conditions...
.
He carried out a number of studies in the evolutionary biology of plants, such as Taraxacum
Taraxacum
Taraxacum is a large genus of flowering plants in the family Asteraceae. They are native to Eurasia and North America, and two species, T. officinale and T. erythrospermum, are found as weeds worldwide. Both species are edible in their entirety...
, Capsella bursa-pastoris and Ranunculus
Ranunculus
Ranunculus is a large genus of about 600 species of plants in the Ranunculaceae. Members of the genus include the buttercups, spearworts, water crowfoots and the lesser celandine....
.
He developed a quotient of similarity in species composition between plant communities - the still much-used Sørensen similarity index
Sørensen similarity index
The Sørensen index, also known as Sørensen’s similarity coefficient, is a statistic used for comparing the similarity of two samples. It was developed by the botanist Thorvald Sørensen and published in 1948....
. He illustrated its use on a data set collected in Danish
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
by Johannes Grøntved
Johannes Grøntved
Johannes Grøntved was a Danish botanist. He made investigations of flora and vegetation in Denmark, the Faroe Islands, Iceland, Greenland and Estonia. He was editor of The Botany of Iceland from vol. 3 part 2.-Selected scientific works:...
, who used Raunkiær's
Christen C. Raunkiær
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...
quantitative method to sample vegetation.
Example of plant name he published:
- Braya intermedia T.J.Sørensen (1954) in Meddelelser om GrønlandMeddelelser om GrønlandMeddelelser om Grønland was a Danish scientific periodical issued by the Commission for Scientific Investigations in Greenland. Founded by Frederik Johnstrup, it was published from 1879 to 1979...
134 (8). - Puccinellia groenlandicaPuccinelliaPuccinellia is a genus of grasses which are known as alkali grass. These grasses grow in wet environments, often in saline or alkaline conditions...
T.J.Sørensen (1953) in Meddelelser om GrønlandMeddelelser om GrønlandMeddelelser om Grønland was a Danish scientific periodical issued by the Commission for Scientific Investigations in Greenland. Founded by Frederik Johnstrup, it was published from 1879 to 1979...
134 (3).
The Arctic campion
Campion
Campion may refer to:-Biology:* Flowering plants of the Caryophyllaceae genera Lychnis and Silene, including:** Silene acaulis, or moss campion, a flower found in Eurasia and North America...
species Silene sorensensis
Silene
Silene is a genus of flowering plants in the family Caryophyllaceae. Common names include campion and catchfly....
was named to his honour.
Selected publications
- Sørensen, T. (1935) Bodenformen und Pfanzendecke in Nordostgrönland. Beiträge zur Theorie der polaren Bodenversetzungen auf Grund von Beobachtungen über deren Einfluss auf die Vegetation in Nordostgrönland. Meddelelser om GrønlandMeddelelser om GrønlandMeddelelser om Grønland was a Danish scientific periodical issued by the Commission for Scientific Investigations in Greenland. Founded by Frederik Johnstrup, it was published from 1879 to 1979...
93 (4). - Sørensen, T. (1941) Temperature relations and phenologyPhenologyPhenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...
of the Northeast GreenlandGreenlandGreenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
flowering plants. Meddelelser om GrønlandMeddelelser om GrønlandMeddelelser om Grønland was a Danish scientific periodical issued by the Commission for Scientific Investigations in Greenland. Founded by Frederik Johnstrup, it was published from 1879 to 1979...
129: 1-305. - Sørensen, T. (1942) Untersuchungen über die Therophytengesellschaften auf den isländischen Lehmflächen ("Flags"). Biologiske Skrifter / Kongelige Danske Videnskabernes Selskab 2 (2).
- Sørensen, T. and Gudjónsson, Gudni (1946) Spontaneous chromosome-aberrants in apomictic TaraxacaTaraxacumTaraxacum is a large genus of flowering plants in the family Asteraceae. They are native to Eurasia and North America, and two species, T. officinale and T. erythrospermum, are found as weeds worldwide. Both species are edible in their entirety...
: morphological and cyto-genetical investigations. Biologiske Skrifter / Kongelige Danske Videnskabernes Selskab 4 (2). - Sørensen, T. (1948) A method of establishing groups of equal amplitude in plant sociology based on similarity of species and its application to analyses of the vegetation on Danish commons. Biologiske Skrifter / Kongelige Danske Videnskabernes Selskab 5: 1-34.
- Sørensen, T. (1953) A Revision of the Greenland Species of PuccinelliaPuccinelliaPuccinellia is a genus of grasses which are known as alkali grass. These grasses grow in wet environments, often in saline or alkaline conditions...
Parl. With contribution to our knowledge of the Arctic PuccinelliaPuccinelliaPuccinellia is a genus of grasses which are known as alkali grass. These grasses grow in wet environments, often in saline or alkaline conditions...
flora in general. Meddelelser om GrønlandMeddelelser om GrønlandMeddelelser om Grønland was a Danish scientific periodical issued by the Commission for Scientific Investigations in Greenland. Founded by Frederik Johnstrup, it was published from 1879 to 1979...
136 (3) 1-179. - Jørgensen, C.A., Sørensen, T. and Westergaard, M. (1958) The Flowering Plants of Greenland. Biologiske Skrifter / Kongelige Danske Videnskabernes Selskab 9 (4).