Geir Hestmark

Image of Geir Hestmark
Norwegian version of this page
Room 3223
Visiting address Blindernveien 31 0371 Oslo
Postal address Postboks 1066 Blindern 0316 Oslo

Academic Interests

  • Ecology and evolution
  • Landscape ecology
  • Biodiversity
  • Ecophysiology
  • High altitude biology
  • Conservation biology
  • South and Middle American biota
  • Fungi
  • Lichens
  • Ice ages & climate
  • Geology
  • History of science
  • Philosophy of science


Higher education

  • Dr. scient. in biology
  • Magister Artium in philosophy



  • 2000, Freedom of Speech Honors Price (Fritt Ords Honnørpris)
  • His biography Istidens Oppdager (2017) of Jens Esmark, the discoverer of ice ages, was in 2018 voted one of the ten best Scandinavian non-fiction books in this century.


  • Fellow of the Norwegian Academy of Science and Letters from 2002, leader of the group for the history and philosophy of science.
  • Member of the board of Finse Alpine Research Center



I collaborate with several universities in Europe and North and South America.

Tags: Ecology, Evolution, Landscape ecology, Biodiversity, Ecophysiology, High altitude biology, Conservation biology, South and Middle American biota, Fungi, Lichens, Geology, History of science, Philosophy of science

Selected publications


Hestmark, G. 2022. Glaciator - Jens Esmark, Ice Ages and Climate Change. Introduction and Chapter 1. Web-publication

Hestmark, G. 2021. Proposal to conserve the name Umbilicaria spodochroa (lichenized Ascomycota) with a conserved type and with that spelling. Taxon 70 (5): 1131-1132.

Hestmark, G. 2021. Siste livbåt fra et synkende Europa. Kronikk Vårt Land 09.06.2021. 

Hestmark, G. 2020. Lykkeskipet Bergensfjord. Verdenskrig og etterkrigsår 1939-1959. Kagge Forlag AS. ISBN 9788248926291. 560 s.

Hestmark, G. 2020. Apostlenes gjerninger: Keilhau og Boeck "oppdager" Jotunfjeldene. GEO 23 (4): 16-21.

Hestmark, G. 2019. On the altitudes of von Humboldt. Proceedings of the National Academy of Sciences of the United States of America 116 (26): 12599-12600.

Hestmark, G. 2018. Hva er ØKOLOGI. Universitetsforlaget, Oslo. ISBN 978-82-150-2796-8.

Hestmark, G. 2018. Jens Esmark’s mountain glacier traverse 1823 – the key to his discovery of ice ages. Boreas 47: 1-10.  Open Access.

Hestmark, G. 2017. Tracings of the north of Europe: Robert Chambers in search of the Ice Age. Annals of Science 74: 262-281.

Hestmark, G. 2017. Oppdagelsen av istiden. Aftenposten Historie nr. 9 (2017): 81-85.

Hestmark, G. 2017. Istidens Oppdager. Jens Esmark, pioneren i Norges fjellverden. En Biografi. Kagge Forlag AS, Oslo.720 s. ISBN: 978-82-489-2027-4

Hestmark, G. 2017. Lectotypification of Umbilicaria torrefacta (Lightf.) Schrad. Lichenologist 49: 167-169.

Hestmark, G. 2017. Lectotypification of Umbilicaria leiocarpa (Umbilicariaceae). Graphis Scripta 29: 12-17.

Hestmark, G. & Nordli, Ø. 2016. Jens Esmark’s Christiania (Oslo) meteorological observations 1816-1838: The first long term continuous temperature record from the Norwegian capital homogenized and analysed. Climate of the Past 12: 2087- 2106. Open Access.

Hestmark, G., Lutzoni, F. & Miadlikowska, J. 2016. Photobiont associations in co-occurring umbilicate lichens with contrasting modes of reproduction in coastal Norway. Lichenologist 48: 545-557.

Hestmark, G. 2016. The lichen genus Umbilicaria in Ecuador. Nordic Journal of Botany 34: 257-268.

Hestmark, G. 2015. Umbilicaria aprina – new to the Pyrenees. Graphis Scripta 27: 42-45.

Hestmark, G. 2015. Lectotypification of Umbilicaria virginis (Umbilicariaceae). The Lichenologist 47: 77-81.

Nordli, Ø., Hestmark, G., Isachsen, K. & Benestad, R. 2015. The Oslo temperature series 1837-2012: Homogeneity testing and temperature analysis. International Journal of Climatology 35: 3486-3504.

Nordli, Ø., Hestmark, G., Isachsen, K. & Benestad, R. 2015. Formidabel temperaturauke. Aftenposten (kronikk) 7. januar 2015.

Hestmark, G. 2014. Charles Lyells norske lærebokseksempel. GEO 17 (7): 72.

Hestmark, G. 2014. Christian Frederiks siste erindring om Norge. GEO 17 (3): 10-11.

       Hestmark, G. 2014. [Review of T. Krüger] Discovering the Ice Ages. ISIS 105 (2): 416-417.

Hestmark, G. 2014. Lectotypification of the name Umbilicaria nylanderiana (Umbilicariaceae). Taxon 63 (4): 914-917.

Miadlikowska J., Kauff, F., Högnabba, F., Oliver J. C. , Molnár, K., Fraker, E., Gaya, E., Hafellner, J., Hofstetter, V., Gueidan, C., Otalora, M., Hodkinson, B., Kukwa, M., Lücking, R., Björk, C., Sipman, H.J.M., Burgaz, A.R., Thell, A., Passo, A., Myllys, L., Goward, T., Fernández-Brime, S., Hestmark, G., Lendemer, J., Lumbsch, T., Schmull, M., Schoch, C., Sérusiaux, E., Maddison, D., A. Arnold, E., Lutzoni, F., & Stenroos, S. 2014. A multigene phylogenetic synthesis for the class Lecanoromycetes (Ascomycota): 1307 fungi representing 1139 infrageneric taxa, 312 genera and 66 families. Molecular Phylogenetics and Evolution 79: 132-168.

       Hestmark, G. 2012. The meaning of ‘metamorphic’ – Charles & Mary Lyell in Norway, 1837. Norwegian Journal of Geology 91: 247-275.

Hestmark, G. 2012. To discover, yes, but top publish...? Jens Esmark, datolite..and thulite. Norwegian Mining Museum, Publication No. 49: 45-52

Hestmark, G., Miadlikowska, J., Kauff, F., Fraker, E., Molnar, K., Lutzoni,F.  2011. Single origin and subsequent diversification of Central Andean endemic Umbilicaria species. Mycologia 103: 45-46

Hestmark, G. 2010. Typification of the Andean taxa of Umbilicaria described by William Nylander. Mycotaxon111: 51-63.

Jettestuen, E., Nermoen, A., Hestmark, G., Timdal, E., Mathiesen, J. 2010. Competition on the Rocks: Community Growth and Tesselation. PLos One 5 (9) e12820. Published 30 September 2010. doi:10.1371/ journal.pone.0012820.

Hestmark, G. 2009. New observations and records for the genus Umbilicaria in Bolivia. Bryologist112 (4): 833-838.

Hestmark, G. 2009. “Her ligger Sneen evig.” – Da Dovre falt – for Esmarks barometer. Historisk Tidsskrift 88: 231-249.

Hestmark, G. 2009. Sula-konglomeratet – fra fossilparadis til istidsbevis. GEO, web og papirutgave.

Hestmark, G. 2009. Da Dovre falt. GEO, web og papirutgave.

Hestmark, G. 2009. Michael Sars. In: Store Norske  Leksikon  web-utgave

Hestmark, G. 2009.Georg Ossian Sars. In: Store Norske  Leksikon  web-utgave

Hestmark, G. 2009.Sem Sæland. In: Store Norske  Leksikon  web-utgave

Hestmark, G. 2009.Iacob Sømme.In: Store Norske Leksikon  web-utgave

Hestmark, G. 2008. ”A primitive country of rocks and people” – Roderick I Murchison’s Silurian Campaign in Norway 1844. Norwegian Journal of Geology88: 117-141

Hestmark, G. 2008. Et [fiktivt!] intervju med lektor Theodor Kjerulf i anledning opprettelsen av en geologisk undersøgelse. GEO: 11 Årgang Nr. 1, pp. 50-52.

Sundquist, B., Haapala, I., Hansen, J. M., Hestmark, G & S. Steinthorsson2008.History of Geology in Norden. Episodes  31 (1): 185-192.

Hestmark, G., Skogesal, O. & Skullerud, Ø. 2007. Early recruitment equals long-term relative abundance in an alpine saxicolous lichen guild. Mycologia 99: 207-214.

Hestmark, G. 2007. Typification of Umbilicaria cinereorufescens. Mycotaxon 100: 235-240.

Hestmark, G. 2007. Innavl ved Universitetet. Kronikk. Aftenposten 23 April 2007.

Hibbett, D. S., Binder, M., Bischoff, J. F., Blackwell, M., Cannon, P. F., Eriksson, O., Huhndorf, S., James, T., Kirk, P. M., Lücking, R., Lumbsch, T., Lutzoni, F., Matheny, P. B., McLaughlin, D. J., Powell, M. J., Redhead, S., Schoch, C. L., Spatafora, J. W., Stalpers, J. A., Vilgalys, R., Aime, M. C., Aptroot, A., Bauer, R., Begerow, D., Benny, G. L., Castlebury, L. A., Crous, P. W., Dai, Y.- C., Gams, W., Geiser, D. M., Griffith, G. W., Gueidan, C., Hawksworth, D. L., Hestmark, G., Hosaka, K., Humber, R. A., Hyde, K., Koljalg, U., Kurtzman, C. P., Larsson, K.-H., Lichtward, R., Longcore, J., Miadlikowska, J., Miller, A., Monclavo, J.-M., Mozley- Standridge, S., Oberwinkler, F., Parmasto, E., Reeb, V., Rogers, J. D., Roux, C., Ryvarden, L., Sampaio, J. P., Schuessler, A., Sugiyama, J., Thorn, R. G., Tibell, L., Untereiner, W. A., Walker, C., Wang, Z., Weir, A., Weiss, M., White, M., Winka, K., Yao, Y.-J., Zhang, N. 2007. A higher-level phylogenetic classification of the Fungi. Mycological Research 111: 509-547.

Gregersen, I.K., Hegseth, M.N., Hestmark, G., Kongsbak, R.H. & and Moe, T.F. 2006. The relationship between thallus mass, surface area and apothecium production in Umbilicaria rigida. Nova Hedwigia 82: 115-121.

Miadlikowska, J., Kauff, F., Hofstetter, V., Fraker, E., Grube, M., Hafellner, J., Reeb, V., Hodkinson, B. P., Kukwa, M., Lücking, R., Hestmark, G., Garcia Otalora, M., Rauhut, A., Büdel, B., Scheidegger, C., Timdal, E., Stenroos, S., Brodo, I., Perlmutter, G., Ertz, D., Diederich, P., Lendemer, J. C., May, P., Schoch, C. L., Arnold, A. E., Gueidan, C., Tripp, E., Yahr, R., Robertson, C., Lutzoni, F. 2006. New insights into classification and evolution of the Lecanoromycetes (Pezizomycotina, Ascomycota) from phylogenetic analyses of three ribosomal RNA- and two protein-coding genes.  Mycologia 98:1088-1103.

Spatafora, J.W., Johnson, D., Sung, G.-H., Hosaka, K., O’Rourke, B., Serdani, M., Spotts, R., Lutzoni, F., Hofstetter, V., Fraker, E., Gueidan, C., Miadlikowska, J., Reeb, V., Lumbsch, T., Lücking, R., Schmitt, I., Aptroot, A., Roux, C., Miller, A., Geiser, D., Hafellner, J., Hestmark, G., Arnold, A.E., Büdel, B., Rauhut, A., Hewitt, D., Untereiner, W., Cole, M.S., Scheidegger, C., Schultz, M., Sipman., H. and Schoch, C. 2006. A five-gene phylogenetic analysis of the Pezizomycotina. Mycologia 98:1018-1028.  


Contributions in: E.A. Drivenes & H.D.Jølle (eds.) Into the Ice. The History of Norwegian Polar Exploration.  Oslo: Gyldendal Norsk Forlag. 2006. 



Hestmark, G., Skogesal, O. and Skullerud, Ø. 2005. Growth, population density and population structure of Cetraria nivalis during 240 years of primary colonization. Lichenologist37: 535–541.

Hestmark, G.2005. Michael Sars. In: J. G. Arntzen (ed.): Bergensere i tusen år. Oslo: Kunnskapsforlaget., pp. 157-158.

HestmarkG, Skogesal O, Skullerud Ø. 2004. Growth, reproduction, and population structure in four alpine lichens during 240 years of primary colonization. Canadian Journal of Botany 82: 1356-1362. 

Hestmark, G. 2004. Umbilicaria. In: Nash III, T., Ryan, B.D., Diederich, P., Gries, C., & Bungartz, F. (eds.): Lichen Flora of the Greater Sonoran Desert Region. Tempe, Arizona. Lichens Unlimited. Arizona State University. Vol. 2: 548-556. 

Hestmark, G. 2004. Michael Sars. In: Norsk Biografisk Leksikon

Hestmark, G. 2004.Georg Ossian Sars. In: Norsk Biografisk Leksikon

Hestmark, G. 2004.Sem Sæland. In: Norsk Biografisk Leksikon

Hestmark, G. 2004.Iacob Sømme.In: Norsk Biografisk Leksikon

Hestmark, G.2004. Kartleggerne. In: E. A. Drivenes & Jølle, H. D. Norsk Polarhistorie. II. Vitenskapene. Gyldendal Norsk Forlag, Oslo, pp. 6-103, 493-504.  

Rydgren, K., Økland, R.H. & G. Hestmark 2004. Disturbance severity and community resilience in a boreal forest. Ecology 85: 1906–1915.

Hestmark, G.1998: “Chemistry before everything”: Theodor Kjerulf and the origin of the Norwegian school of geochemistry. In: B. Fritscher & F. Henderson (eds.): Toward a  history of mineralogy, petrology, and geochemistry. Algorismus. Studien zur Geschichte der Mathematik und der Naturwissenschaften.Institut für Geschichte der Naturwissenschaften. München. Vol 23: 219-224

Bliksrud, L., Hestmark, G. & Rasmussen, T. 2002: Norsk Idéhistorie IV. Vitenskapens Utfordringer 1850-1920. Oslo: Aschehoug (W. Nygaard): 

Ramstad, S. & Hestmark, G. (2001) Population structure and size-dependent reproductive effort in Umbilicaria spodochroa. Mycologia 93: 453-459.

Hestmark, G. (2001). Ernst Haeckel i Bergen 1869. Kronikk. Bergens Tidende  02.05.2001.

Hestmark, G. (2001) Frans Emil Wielgolaski – 70 år. Blyttia

Hestmark, G. (2001) Book Review. ISIS  92:

Hestmark, G. (2000). Oeconomia Naturae L. Millennium essay. Nature, 405: 19.

Hestmark, G.(2000). Temptations of the tree. Millennium essay. Nature, 408: 911.

Hestmark, G.(2000). The ecophysiology of lichen population biology. New Aspects in Cryptogamic Research. Contributions in Honour of Ludger Kappen. Bibliotheca Lichenologica 75: 397-403.

Ramstad, S. & Hestmark, G. (2000) Effective neighbourhoods for a saxicolous lichen. Mycological Research 104: 198-204.

Czeczuga, B., Kilias, H., Czeczuga-Semeniuk, E., Muhr, L.-E., Lumbsch, H. T., Hestmark, G. (2000) Carotenoids in the thalli of lichen species from central Europe. Journal of the Hattori Botanical Laboratory 89: 299-311.

Hestmark, G.(2000) Review.   ISIS, 91: 805-806. 


Hestmark, G.(1999). Vitenskap og nasjon - Waldemar Christopher Brøgger 1851-1905. Oslo, Aschehoug & Co. (W. Nygaard). 890 s. (862 pp. + 28 pp. illustr.). 




Sletvold, N. & Hestmark, G. (1999). A comparative test of the predictive power of neighbourhood models in natural populations of Lasallia pustulata. Canadian Journal of Botany77: 1655-1661


Hestmark, G.(1998). Planter i åkerlandskapet - sjelden å være vanlig, vanlig å være sjelden. I: E. Framstad et al. (red.), I: E. Framstad & I. Lid (red.), Jordbrukets kulturlandskap. Forvaltning av miljøverdier. Oslo: Universitetsforlaget. s.113-120.

Hestmark, G.,Rolf A. Ims & Erik Framstad (1998): Biologisk mangfold i intensivt drevet åkerlandkap - trusler og mottiltak.  I: E. Framstad & I. Lid (red.), Jordbrukets kulturlandskap. Forvaltning av miljøverdier. Oslo: Universitetsforlaget. s.148-153. 

Hestmark, G.(1998). Når ble naturvitenskapen uleselig ? I: T. B. Eriksen og E.B. Johnsen (red.): Norsk Litteraturhistorie. Sakprosa fra 1750 til 1995, Bd. 1, pp. 659-668. Oslo: Universitetsforlaget.

Hestmark, G.(1998). En nasjonal-evolusjonær katekisme. I: E.B. Johnsen & T. B. Eriksen og (red.): Norsk Litteraturhistorie. Sakprosa fra 1750 til 1995, Bd. 1, pp. 708-716. Oslo: Universitetsforlaget.

Hestmark, G.(1998). “Chemistry before everything”: Theodor Kjerulf and the origin of the Norwegian schoool of geochemistry. In: B. Fritscher & F. Henderson (eds.):Toward a  history of mineralogy, petrology, and geochemistry. Algorismus. Studien zur Geschichte der Mathematik und der Naturwissenschaften. Institut für Geschichte der Naturwissenschaften. München. Vol 23: 219-224.

Rydgren, K., Hestmark, G. & Økland, R. (1998). Revegetation following experimental disturbance in a boreal old-growth Picea abies forest. Journal of Vegetation Science 9: 763-776.

Berge, G., Nordal, I. & Hestmark, G. (1998). The effect of breeding systems and pollination vectors on the genetic variation of small plant populations within an agricultural landscape. Oikos  81: 17-29.             

Hestmark, G.(1997). Competitive behaviour of umbilicate lichens - an experimental approach. Oecologia  111: 523-528.

Hestmark, G.(1997): Gap-dynamics, recruitment and individual growth in populations of Lasallia  pustulata. Mycological Research 101: 1273-1280.

Hestmark, G.(1997): Growth from the center in an umbilicate lichen. The Lichenologist 29: 379-383.

Hestmark, G.(1997): Species diversity and reproductive strategies in the family Umbilicariaceae on high equatorial mountains - with remarks on global patterns. Bibliotheca  Lichenologica 68: 195-202.

Hestmark, G (1997): Plantelivet på Finse. s. 22-25, i L. Sømme & E. Østbye (red): Finse - et senter for høyfjellsforskning. Et skrift til 25 års jubileet for Høyfjellsøkologisk forskningsstasjon, Finse 1972-1997. Høyfjellsøkologisk forskningsstasjon, Finse.

Hestmark, G. (1997) Kalkunslakt. Naturen 121: 270-275.

Hestmark, G., Schroeter, B. & Kappen, L.(1997): Intrathalline and size-dependent patterns of activity in Lasallia pustulata and their possible consequence for competitive interactions. Functional  Ecology  11: 318-322.

Rydgren, K. & Hestmark, G. (1997): The soil propagule bank in a boreal old-growth spruce forest: variation with depth and its relation to aboveground vegetation. Canadian  Journal  of  Botany 75: 121-128.

Berge, G. & Hestmark, G. (1997): Composition of seed banks of roadsides, stream verges and agricultural fields in southern Norway. Annales Botanici Fennici  34: 77-90.

Sletvold, N. & Hestmark, G. (1997).Thallus growth asymmetry and habitat inclination in Lasallia  pustulata. The  Bryologist 100: 465-466.

Nordal, I., Hestmark, G. & Solstad, H. (1997): Reproductive biology and demography of Papaver  radicatum - A key species in Nordic plant geography. Opera  Botanica132: 77-88.

Hestmark, G.(1996): FRAM - i det 'ukjendte'. Naturen 120: 171-175.

Hestmark, G.(1996): Nansen - Vitenskaperen. In: O. Christensen & A. Skoglund: Nansen ved to århundreskifter. Oslo. Aschehoug/Norsk Folkemuseum. pp. 128-136. 

Kappen, L., Schroeter, B., Hestmark, G. & Winkler, J. B.(1996): Field measurements of photosynthesis of umbilicarious lichens in winter. Botanica Acta 109: 292-298.

Kappen, L., Schroeter, B., Scheidegger, C., Sommerkorn, M. & Hestmark, G. (1996): Cold resistance and metabolic activity of lichens below 0oC. Advances in Space Research 18, No. 12: (12)119-(12)128.

Hestmark, G. (1995): Fridtjof Nansen and the Spirit of Northern Wilderness. In: Vance G. Martin & Nicholas Tyler: Arctic Wilderness - The 5th World Wilderness Congress. North American Press, Golden, Colorado. pp. 113-117. 

Hestmark, G.(1994): Kulturlandskapsverdier og vitenskapelig forskning. Rapport fra forskningskonferanse på kulturlandskapet, Sundvollen, Ås, p. 67.

Hestmark, G.(1994): Universitetet og polarforskningen. Apollon1/94: 26-27.

Hestmark, G.(1993): Umbilicaria dendrophora. Mycotaxon 46: 211-215.

Hestmark, G.(1993): Fridtjof Nansen og arktisk geologi. Fridtjof Nansen Minneforelesning 1992. Det Norske Videnskaps-Akademi i Oslo. Issued separately. Also printed in Det Norske Videnskaps-Akademis Årbok 1992 (1993): 345-374.

Hestmark, G.(1993): Arne Næss. In: T.B. Eriksen (ed.) Vestens Tenkere. Oslo: H. Aschehoug & Co. (W. Nygaard), Vol.3, pp. 299-312.

Hestmark, G.(1993): Paul Feyerabend. In: T.B. Eriksen (ed.) Vestens Tenkere. Oslo: H. Aschehoug & Co. (W. Nygaard), Vol.3, pp.324-333.  

Hestmark, G.(1993): Økologien og mennesket. Impuls, tidsskrift for psykologi  47 (2-1993): 3-6.

Hestmark, G.(1992): Sex, size, competition and escape - strategies of reproduction and dispersal in Lasallia  pustulata (Umbilicariaceae, Ascomycetes).  Oecologia 92: 305-312.

Hestmark, G.(1992): Conidiogenesis in five species of UmbilicariaMycological Research 96: 1033-1043.

Hestmark, G.(1992): Notes on the genus Umbilicaria in Corsica. Cryptogamie - Lichenologie - Bryologie13: 341-347.

Hestmark, G.(1992): Brøgger og Nansen - en vitenskapelig romanse. Norsk Vitenskapshistorisk Selskap - Årbok 1989-1991, Oslo, pp. 7-42.

Hestmark, G.(1992): Roderick I. Murchisons reisedagbok fra Norge i året 1844. Norsk Vitenskapshistorisk Selskap - Årbok 1989-1991, Oslo, pp. 124-139.

Hestmark, G.(1991): Teleomorph-anamorph relationships in Umbilicaria. I. Making the connections. The Lichenologist 23: 343-359.

Hestmark, G.(1991): Teleomorph-anamorph relationships in Umbilicaria. II. Patterns in propagative morph production. The Lichenologist 23: 361-380.

Hestmark, G.(1991): To Sex or not to Sex...Structures and Strategies of Reproduction in the Family Umbilicariaceae (Lecanorales, Ascomycetes). Sommerfeltia Supplement 3: 1-47.

Hestmark, G.(1991): Fridtjof Nansen and the Geology of the Arctic. Earth Sciences History 12: 168-212.

Hestmark, G.(1990): Thalloconidia in the genus UmbilicariaNordic Journal of Botany 9: 547-574.

Roll-Hansen, N. & Hestmark, G (1990): Miljøforskning mellom vitenskap og politikk. En studie av forskningspolitikken omkring andre fase av storprosjektet "Sur nedbørs virkning på skog og fisk" (SNSF), 1976-1980. NAVF's Utredningsinstitutt, Melding 1990: 2., 160 pp.

Hestmark, G. (1989):  Den glemte kulturhistorien. (Kronikk) Aftenposten 7. mars 1989.  

Published Nov. 3, 2010 3:27 PM - Last modified Oct. 3, 2022 9:04 AM