Gustaf Einar du Rietz | |
|---|---|
 Einar Du Rietz in 1932 | |
| Born | (1895-04-25)25 April 1895 |
| Died | 7 March 1967(1967-03-07) (aged 71) |
| Alma mater | Uppsala University |
| Spouse(s) | Greta Sernander, divorced 1951;Margareta Witting |
| Children | 4 |
| Scientific career | |
| Fields | Lichenology,phytosociology |
| Institutions | Uppsala University |
| Author abbrev. (botany) | Du Rietz[1] |
Gustaf Einar Du Rietz (25 April 1895 – 7 March 1967) was a Swedish botanist andlichenologist. His research interests includedplant ecology,lichen taxonomy, andbiogeography. He was a leading figure in theUppsala school ofphytosociology–the study of groups of species of plants that are usually found together–and is recognised for his role in advancing this field of science and for mentoring future lichenologists. He led theSwedish Australasian Botanical Expedition of 1926–27, a seven-month research tour of various locations. He was married toGreta Sernander, who was also a lichenologist. During the expedition, Du Rietz and his wife researched the vegetation in New Zealand, Australia, and Java, focusing on mountain lichens and their potential asbioindicators for environmental conditions. They collected around 3000 specimens, contributing significantly to the study of bipolar lichens andforest ecology, despite challenges in processing all the samples upon return to Sweden. Several species have beennamed in his honour. In 1949, Du Rietz was elected to theRoyal Swedish Academy of Sciences and contributed significantly tonature conservation efforts in Sweden.
Gustaf Einar Du Rietz was born inBromma on 25 April 1895.[2] He was the second son of theCEO ofStockholms Benmjölsfabrik AB [sv], the engineer Hjalmar Du Rietz and Charlotta Sofia Mathilda (born Kullman).[3] His younger brother, Carl Du Rietz (1905–1986), pursued a career as a high school teacher.[4] Du Rietz finished grade school in 1912, and became aFilosofie kandidat in 1917. The seventeen-year-old who registered at Uppsala University developed a varied interest in outdoorbotany, especially inlichens and coastal areas, passions that he maintained throughout his life. He especially liked to explore the lifeforms present in the outer archipelago of theBaltic Sea and onJungfrun, a nature reserve on the island of Gotland.[3]
Du Rietz graduated with alicentiate degree fromUppsala University in 1921, and received anassociate professorship the same year. His thesis was titledZur methodologischen Grundlage der modernen Pflanzensoziologie ('Fundamental Methods of Plant Sociology'). The dissertation was translated into German and printed inVienna for economic reasons, reflecting the scientific language preference in the Nordic countries at the time. Thedefence, held in Uppsala in spring 1921, was reportedly dramatic. The thesis focused on the methodological foundations of modernplant sociology, covering topics such aslife forms,stratification, and the associations based on dominant species' life forms, as well as the concept of constancy andfield boundary lines. Although logical and impressive for its era, the dissertation was quite schematic and faced criticism, particularly regarding the so-calledKonstanzgesetze ('laws of constancy', i.e., principles regarding the regular occurrence of certain plant species within specific types of vegetation communities or habitats). In 1922 Du Rietz was awarded aPhD for his work.[3]
One of Du Rietz's professors at Uppsala University wasRutger Sernander, a popular lecturer who pioneered the study of plant ecology at the institution.[5] One of Du Rietz's earliest publication was on the material collected by Sernander in Norway.[6] Du Rietz later continued Sernander's work. From 1917 to 1923, Du Rietz served as an associate assistant professor at the Department of Plant Biology. He then transitioned to the role ofcurator at theBotanical Museum in Uppsala, a position he held from 1924 to 1927.[7] Du Rietz was also the leader of the biological geological work atAbisko Scientific Research Station, and general secretary of the international plant geographical excursion through Scandinavia in 1925. Du Rietz undertook several study trips within and outside Sweden, scientific expeditions to New Zealand and Australia and in his research mainly devoted on plant sociology andlichenology. In 1929 he co-founded theSvenska Växtgeografiska Sällskapet ('Swedish Phytogeographical Society').[8]
Having been adocent since 1921,[7] in 1934 Du Rietz was appointed as both professor of plant ecology at Uppsala University (emeritus in the early 1960s),[8] and as the director of the institute. He had served temporarily in this latter position since Sernander's retirement in November 1931.[9] Sernander established the "Uppsala school", known for treating plant communities as tangible entities rather than abstract constructs and for advocating an empirical, inductive approach that emphasised life forms, stratification, dominance, and the significance of smaller non-flowering plants and fungi (cryptogams). This approach was primarily analytical, focusing on the analysis, characterisation, and classification of vegetation independently of habitat factors, which were to be considered subsequently.[3] Du Rietz would later carry on the research traditions of the "Uppsala school".[10] Du Rietz taught high-level material without being difficult to understand, and became popular among botany students. Under his supervision, the plant biology seminar flourished. According to his biographer, the Swedish plant ecologist Hugo Sjörs, Du Rietz was regarded as an inspiring academic teacher. It is reported that his students were inclined to undertake large and challenging projects, often requiring considerable time to complete. Du Rietz valued thorough documentation and comprehensive reporting of research materials. The scope of plant groups and environments studied by the students was diverse, predominantly involving field research. Although Du Rietz insisted on formal accuracy, he reportedly did not often intervene directly with the content of students' dissertations. This approach is said to have fostered a supportive environment that contributed to the development of doctoral students into independent researchers.[8] A few of his students,Sten Ahlner,Gunnar Degelius,Torsten Hasselrot, andRolf Santesson, later became notable lichenologists.[11]Stig Waldheim andOve Almborn were also influenced by the Uppsala school of phytogeography even though they were associated withLund University.[12]
Du Rietz resumed his international contacts on a large scale during the first majorInternational Botanical Congress after the Second World War, inStockholm in 1950. Einar was then responsible for the plant geography section as well as for its excursions and the many guide books for these that were published. He personally led a series of excursions: fromVästergötland toUppland, anarchipelago excursion, and a very frequently visited mountain excursion in theAbisko area; in the latter, he brought amegaphone so his voice could be heard over the wind. Sjörs regarded these events as the fourth pinnacle in Du Rietz's professional career, following his doctoral dissertation, the 1925 field trip, and achieving his professorial qualifications.[8]
After this phase of his career, Du Rietz started researching the plant genusEuphrasia (eyebrights), both local and foreign species.[8]
In 1924, Du Rietz marriedGreta Sernander, daughter ofRutger Sernander, after five years of engagement.[13] In addition to a son who died at an early age, they had three children: Kerstin, Rolf and Ingrid. They were divorced in 1951 after a few difficult years.[13] He later remarried Margareta Witting (1920–2006) who was one of his former students.[8] She studied the chemistry ofbog water; Du Rietz would sometimes hand-squeezemicroalgae out ofmoss and bring it to her in tubes for study.[8]
Du Rietz died of aheart attack in Uppsala on 7 March 1967, at the age of 72. He was outdoors, walking on his way to work.[8]
In 1926–27, Du Rietz and his wife conducted a research trip to New Zealand, including itssub-Antarctic islands, with visits to a large part of Australia and Java. The purpose of trip, known as the Swedish Australasian Botanical Expedition, was to compare vegetation across the visited countries. One of Du Rietz's research objectives was to determine whether a detailed study of mountain lichens could increase the recognised Arctic elements within New Zealand's flora. He also aimed to evaluate whether certain lichens could serve asbioindicators for assessing foresthumidity levels.[14] This research intended to identify which forest tree species could replenish areas cleared bysawmilling,[15] the fear of a possible wood shortage was an environmental concern causing widespread anxiety in New Zealand at that time.[14] A local newspaper report noted his interest in studyingfoliicolous lichens (lichens that grow on tree leaves), which are rare outside tropical regions.[16] Du Rietz's New Zealand itinerary included theTararua Mountains, montaneresearch stations operated byCanterbury College,Hokitika,Mount Cook, and thefjords of northwest Otago.[15] He was already somewhat familiar with New Zealand lichens, having previously corresponded with plant geographerLeonard Cockayne and botanistHarry Allan, the latter of whom had sent lichen samples to Du Rietz for study.[14]
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Although Greta Sernander Du Rietz was an accomplished lichenologist in her own right, she did not have any formal university training in the subject, having been taught instead by her father, who was Professor of Botany at Uppsala University. In New Zealand, she primarily collated and preserved specimens collected by her husband, and only began writing about lichens after their divorce, later in her life.[14][13] The local newspaper,The Evening Post, reported Du Rietz's visit, and described him as "virtually the founder of the important Swedish school of ecology" and "probably the foremost expert regarding lichens".[15]
The New Zealand part of the trip was coordinated by Leonard Cockayne, working for theNew Zealand State Forest Service.[8] Du Rietz had also corresponded withHenry A. Gleason, who had sent him lichen samples for identification in 1925.[14] Du Rietz returned with about 3,000 specimens that he was unable to fully process due to his academic commitments in Sweden.[8] Nevertheless, some of his collections were included inAdolf Hugo Magnusson's 1943 report,[17] and his collections ofPseudocyphellaria were an integral part of a major revision of that genus published in 1988.[18] He was the first to report on the existence of bipolar lichens (i.e., identical taxa in the polar or subpolar regions of the Northern and Southern hemispheres) in New Zealand.[19] Bipolar lichens were a particular interest of his,[10] and he wrote about species he encountered in Arctic areas and cool areas of the Southern Hemisphere.[20][21]
Einar Du Rietz's legacy is marked by significant contributions tonature conservation, academic teaching, and plant sociology. In addition to mentoring numerous students, he was deeply committed to preservingbiotopes and small cryptogams, which he valued as much as the more conspicuousflowering plants. As a member of theSwedish Royal Academy of Sciences' nature conservation committee, he played a key role in surveying and documenting Swedish natural habitats, particularly those threatened by industrial expansion. Despite being more theoretical in his approach to vegetation research and not producing major vegetationmonographs, he authored numerous summarising works and delivered factual yet engaging lectures, often enhanced with vivid colour photographs. As an inspirational teacher, Du Rietz guided his students through complex field research, fostering a significant degree of independence and shaping them into researchers with broad expertise. His dedication to the field and his students impacted the direction and development of plant geographical studies in Sweden, leaving a legacy in both academic and conservation communities.[8]
In 1949, Du Rietz was elected to theRoyal Swedish Academy of Sciences. As a member of the Swedish Academy of Sciences'nature conservation committee, he organized surveys of the shores of the lakes and river stretches that were threatened by the ongoing expansion of hydroelectric power inNorrland.[8] When Du Rietz, as emeritus, turned 70, many of his former students gathered to write a 300-page collection of papers titledThe Plant Cover of Sweden (Acta Phytogeographica Suecica 50, 1965), recognising him as the foremost explorer of Swedish vegetation.[8] The volume, a tribute to Du Rietz's significant scientific contributions, includes 43 articles encompassing a wide spectrum of Swedish vegetation. This compilation served not only as an acknowledgment of Du Rietz's impact on phytosociology and botanical studies in Sweden but also aimed to provide an accessible resource to a global audience, reflecting the international reach and influence of his work.[22] Decades after his death, his botanical collections from riverbanks and lakeshores in northwestern Sweden have been instrumental in expanding the known distributions of several species.[23][24] Ultimately, his collections were distributed among theherbaria] of Uppsala,Lund, andStockholm.[25] An obituary described Du Rietz as "one of the leading and most dynamic lichen taxonomists of the 1920s".[26]
In 1935,Vilmos Kőfaragó-Gyelnik named the genusDurietzia after Du Rietz;[27][7] this genus has since been madesynonymous withIonaspis. In 1964,Carroll William Dodge proposed thesubgenusDurietzia of genusLobaria, writing "I take great pleasure dedicating this to my friend Einer Du Rietz, who first pointed out to me some of the physiologic and ecologic implications of therimose cortex in species ofParmelia, and argued for its recognition as a taxonomiccharacter".[28] Isao Yoshimura tried to promote this subgenus to a genus in 1998, but it is not an accepted name as it is ajunior homonym of Gyelnik's name; thetaxon is now known as genusLobariella.[29]
Du Rietz has also had several species named after him,[30] including the lichensAcarospora durietziiH.Magn. (1924);Caloplaca durietziiH.Magn. (1953);Collema durietziiDegel. (1974);Degelia durietziiArv. & D.J.Galloway (1981);Lecidea durietziiH.Magn. (1943);Lecidora durietziiMotyka (1996);Placopsis durietziorumD.J.Galloway (2004);Pseudocyphellaria durietzii Galloway (1983);Psoroma durietziiP.James & Henssen (1975);Umbilicaria durietziiFrey (1949);Usnea durietziiMotyka (1937);Verrucaria durietziiI.M.Lamb (1948);Xanthoparmelia durietziiHale (1987); the flowering plantsCelmisia durietziiCockayne & Allan (Ohan),Euphrasia durietziiYamam., andEuphrasia durietzianaOhwi; and the diatomFragilaria durietziiA.Cleve-Euler.
Between the years 1912–1966, Einar Du Rietz published about 250 scientific works. Many are listed in Sjörs' biography of him; some of his major works include:[8]
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