Hagbard Jonassen
Encyclopedia
Hagbard Jonassen was a Danish botanist, quaternary geologist, war resister
and nuclear disarmament
proponent. He made a lasting impact on the interpretation of pollen diagrams, incl. the use of modern pollen deposition in moss
polsters to aid interpretation and the consideration of pollen productivity in different types of vegetation.
at the University of Copenhagen
and obtained his M.Sc. (cand. mag.) in 1931. He then became an assistant to Knud Jessen
, who was the professor of botany
at the University of Copenhagen
and director of the Copenhagen Botanical Garden and one of the pioneers of pollen analysis
in quaternary geology. He assisted Jessen
in his work on Irish
vegetation history.
Jonassen’s list of papers is short. Nevertheless, his doctoral dissertation from 1950 had a lasting impact on its field in two respects. Jonassen pioneered the use pollen collected from moss
polsters to assess the modern pollen rain and, by comparison with the species composition of surrounding vegetation, he was able to infer past vegetation from fossil pollen spectra much more accurately than before. Hence, he concluded that 1) cultivated crops such as cereals (except rye
), beet
, clover
and lucerne
had very low pollen production and the pollen signal from such areas would have a much higher detection limit than more productive types of land. Similarly, the pollen signal from un-wooded terrain like heathland and grassland
could be completely swamped in pollen production from wind-pollinated
trees. 2) Pollen dispersal in forest very limited local due to restricted wind speed, which was later confirmed by detailed investigations by Henrik Tauber.
Jonassen’s work on the Holocene
history of heathlands in Jutland
showed that forest had preceded heathland. He hypothesized that climate change had led to abandonment of agriculture
and heathland expansion. More recent investigations in Denmark
and Norway
have shown that heathland expansion was metachronous, i.e. occurring at multiple separate locations to different times, suggesting an overriding impact of humans and less of importance for climate change.
, he was a co-founder of the Danish
branch of War Resisters' International
in 1926. He served as its president 1936-42 and again from 1964. He also co-founded the humanitarian non-governmental organisation Mellemfolkeligt Samvirke
in 1944. In the 1960s
, Jonassen engaged himself in the popular struggle against nuclear weapons.
War resister
A war resister is a person who resists war. The term can mean several things: resisting participation in all war, or a specific war, either before or after enlisting in, being inducted into, or being conscripted into a military force....
and nuclear disarmament
Nuclear disarmament
Nuclear disarmament refers to both the act of reducing or eliminating nuclear weapons and to the end state of a nuclear-free world, in which nuclear weapons are completely eliminated....
proponent. He made a lasting impact on the interpretation of pollen diagrams, incl. the use of modern pollen deposition in moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
polsters to aid interpretation and the consideration of pollen productivity in different types of vegetation.
Professional life
He studied natural historyNatural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
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...
and obtained his M.Sc. (cand. mag.) in 1931. He then became an assistant to Knud Jessen
Knud Jessen
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...
, who was the professor of botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
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...
and director of the Copenhagen Botanical Garden and one of the pioneers of pollen analysis
Pollen analysis
Analysis of the distribution of pollen grains of various species contained in surface layer deposits, especially peat bogs and lake sediments, from which a record of past climate may be inferred. Because the lake sediments accumulate over time, a core of the mud will show that the mud at the bottom...
in quaternary geology. He assisted Jessen
Knud Jessen
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...
in his work on Irish
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
vegetation history.
Jonassen’s list of papers is short. Nevertheless, his doctoral dissertation from 1950 had a lasting impact on its field in two respects. Jonassen pioneered the use pollen collected from moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
polsters to assess the modern pollen rain and, by comparison with the species composition of surrounding vegetation, he was able to infer past vegetation from fossil pollen spectra much more accurately than before. Hence, he concluded that 1) cultivated crops such as cereals (except rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
), beet
Beet
The beet is a plant in the Chenopodiaceae family which is now included in Amaranthaceae family. It is best known in its numerous cultivated varieties, the most well known of which is the purple root vegetable known as the beetroot or garden beet...
, clover
Clover
Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...
and lucerne
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...
had very low pollen production and the pollen signal from such areas would have a much higher detection limit than more productive types of land. Similarly, the pollen signal from un-wooded terrain like heathland and 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...
could be completely swamped in pollen production from wind-pollinated
Anemophily
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Anemophilous plants may be either gymnosperms or angiosperms ....
trees. 2) Pollen dispersal in forest very limited local due to restricted wind speed, which was later confirmed by detailed investigations by Henrik Tauber.
Jonassen’s work on the Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
history of heathlands in Jutland
Jutland
Jutland , historically also called Cimbria, is the name of the peninsula that juts out in Northern Europe toward the rest of Scandinavia, forming the mainland part of Denmark. It has the North Sea to its west, Kattegat and Skagerrak to its north, the Baltic Sea to its east, and the Danish–German...
showed that forest had preceded heathland. He hypothesized that climate change had led to abandonment of agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
and heathland expansion. More recent investigations in Denmark
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...
and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
have shown that heathland expansion was metachronous, i.e. occurring at multiple separate locations to different times, suggesting an overriding impact of humans and less of importance for climate change.
Peace activism
As a young student and army conscriptConscription
Conscription is the compulsory enlistment of people in some sort of national service, most often military service. Conscription dates back to antiquity and continues in some countries to the present day under various names...
, he was a co-founder of the 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...
branch of War Resisters' International
War Resisters' International
War Resisters' International is an international anti-war organization with members and affiliates in over thirty countries. Its headquarters are in London, UK.-History:...
in 1926. He served as its president 1936-42 and again from 1964. He also co-founded the humanitarian non-governmental organisation Mellemfolkeligt Samvirke
Mellemfolkeligt Samvirke
Mellemfolkeligt Samvirke is a Danish, politically independent humanitarian non-governmental organisation that struggles for a fairer world...
in 1944. In the 1960s
1960s
The 1960s was the decade that started on January 1, 1960, and ended on December 31, 1969. It was the seventh decade of the 20th century.The 1960s term also refers to an era more often called The Sixties, denoting the complex of inter-related cultural and political trends across the globe...
, Jonassen engaged himself in the popular struggle against nuclear weapons.