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Christer Björkman

Christer Björkman
Christer Björkman's research interests are plant/insect and tritrophic interactions, insect ecology, forest entomology, plant resistance, biological control, population biology, and insect outbreaks. One theme is to understand the mechanisms behind outbreaks and how population processes are affected by environmental drivers connected to global change.


“Why is the world green?” or “Why is not more of the green biomass eaten by herbivores?” is a question that function as a foundation for my research and has stimulated a lot of research for more than 50 years. There is still more to learn. Understanding the basic mechanisms involved in interactions between plants, herbivorous insects and their natural enemies are crucial when trying to develop tools for sustainable forest and crop protection. The goal of our research is to provide such knowledge.

Main study systems

Forest insects, particularly the European pine sawfly (Neodiprion sertifer).

It is anticipated that insect outbreaks may become more frequent and severe in the future as a consequence of the ongoing global change. However, our knowledge about the mechanisms triggering the outbreaks forest and other insects are still not very well known. We study how (i) environmental heterogeneity and (ii) multiple stressors (moose browsing + insect herbivory) affect pine trees and ecological interactions. 

Insects on willows, mainly leaf beetles (Phratora vulgatissima) and predatory omnivorous  bugs (Miridae and Anthocoridae).

Willows are grown as a renewable source of energy and leaf beetles are the most severe pests. Willow growth is reduced by 40% when heavily defoliated. Insecticides is not an option and  there is a need to control the beetles via resistant plants and biological control. Indirect plant resistance, acting via the natural enemies, is an important aspect in our studies. We also conduct long-term studies of the population dynamics of leaf beetles and their natural enemies in planted and natural willow stands.


Research projects:

Forest management to mitigate the risk for insect damage

Population dynamics of insect herbivores and their natural enemies

Plant resistance: Protecting conifer seedlings against insects

Role of insect herbivores and ecological interactions in the spread of vector-borne diseases


PhD students 
Fredrika Wrethling (2020-, co-supervisor)
Kristina Berggren (2018- )
Dragos Cocos (PhD, 2023, co-supervisor)
Yayuan Chen (PhD, 2021)
Michelle Nordkvist (PhD, 2020)
Davide Bellone (PhD, 2018)
Kim Karlsson Moritz (PhD, 2017, co-supervisor)
Jörg Stephan (PhD, 2015) 
Anna-Sara Liman (PhD, 2015)
Ida Kollberg (PhD, 2013)
Freddy Miranda (PhD, 2011)
Peter Dalin (PhD, 2004)
Lisette Lenoir (PhD, 2001, co-supervisor)
Agnis Smits (PhD, 2001, co-supervisor)
Weronika Linkowski (Fil. Lic., 2000, co-supervisor)

Post docs
Xiaoning ('Nina') Zhang (2020- ) Award from His Majesty Carl XVI Gustaf's science fund
Adriana Puentes (2014- 2017) Award from His Majesty Carl XVI Gustaf's science fund
Tea Ammunét (2011 – 2014)
Mikaela Torp (2010 – 2013)
Maartje Klapwijk (2009 – 2012) Award from His Majesty Carl XVI Gustaf's science fund
Anna Lehrman (2008 – 2010)
Johan Stenberg (2008 – 2010) Award from His Majesty Carl XVI Gustaf's science fund
Enric Vila (2006 – 2007)
Gaétan Moreau (2006)

Master’s students
Agnès Brosset (2017)
Sabine Barets (2016)
Carin Eriksson (2010)
Hans Johansson (2009) Hampus von Posts Prize for best Master’s thesis
Lina Grönberg (2007) Hampus von Posts Prize for best Master’s thesis
Linda Larsson (2007) Hampus von Posts Prize for best Master’s thesis
Alban Maisonnasse (2006)
Nina Fries (2006, co-supervisor)
Karin Ahrné (2002)
Anna-Sara Liman (2002)
Peter Dalin (1999)
Benita Bengtsson (1997)
Georg Nygren (1997)
Peter Zonneveld (1997)

Selected publications

Selected recent publications      (Press Title = link to publication) 

Northward range expansion of rooting ungulates decreases detritivore and predatory mite abundances in boreal forests
Maaroufi NI, Taylor AR, Ehnes RB, Andrén H, Kjellander P, Björkman C, Kätterer T & Klapwijk MJ (2022)
Royal Society open science, 9: 211283.

Global change calls for novel plant protection: reviewing the potential of omnivorous plant-inhabiting arthropods as and defence inducers
Zhang NXN, Stephan JG, Björkman C & Puentes A (2021)
Current Opinion in Insect Science, 47: 103-110.

Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect
Chen YY, Puentes A, Björkman C, Brosset A & Bylund H (2021) 
Frontiers in Plant Science, 12: 695867.

Plant Mediated Interactions: Lower Sawfly Survival on Pines Previously Browsed by Moose
Nordkvist M, Björkman C & Klapwijk MJ (2021)
Frontiers in Ecology and Evolution, 9: 666069.

When is it biological control? A framework of definitions, mechanisms, and classifications
Stenberg JA, Sundh I, Becher PG, Björkman C, Dubey M, Egan PA, Friberg H, Gil JF, Jensen DF, Jonsson M, Karlsson M, Khalil S, Ninkovic V, Rehermann G, Vetukuri, RR & Viketoft M (2021)
Journal of Pest Science, 94: 665-676.

Ecological restoration for biodiversity conservation triggers response of bark beetle pests and their natural predators
Hekkala AM, Kärvemo S, Versluijs M, Weslien J, Björkman C, Löfroth T & Hjälten J (2021)
Forestry, 94: 115-126.

Effect of forest stand type on host plant quality and direct and indirect effects on pine sawfly performance
Bellone D, Björkman C, Schmidt A, Gershenzon J & Klapwijk MJ (2021) Agricultural and Forest Entomology, 23: 163-172.

Seasonal timing and recurrence of methyl jasmonate treatment influence pine weevil damage to Norway spruce seedlings
Chen YY, Bylund H, Björkman C, Fedderwitz F & Puentes A (2021) 
New Forests, 52: 431-448.

Interacting effects of insect and ungulate herbivory on Scots pine growth
Nordkvist M, Klapwijk MJ, Edenius LR & Björkman, C (2020)
Scientific Reports, 10: 22341.

Pathologists and entomologists must join forces against forest pest and pathogen invasions
Jactel H, Desprez-Loustau M-L, Battisti A, Brockerhoff E, Santini A, Stenlid J, Björkman C, Branco M, Dehnen-Schmutz K, Douma JC, Drakulic J, Drizou F, Eschen R, Franco JC, Gossner MM, Green S, Kenis M, Klapwijk MJ, Liebhold AM, Orazio C, Prospero S, Robinet C, Schroeder M, Slippers B, Stoev P, Sun J, van den Dool R, Wingfield MJ & Zalucki MP  (2020) 
NeoBiota, 58: 107-127.

Complex responses of global insect pests to climate warming
Lehmann P, Ammunét T, Barton M, Battisti A, Eigenbrode SD, Jepsen JU, Kalinkat G, Neuvonen S, Niemelä P, Økland B, Terblanche JS & Björkman C (2020)
Frontiers in Ecology and the Environment, 18: 141-150. 

Top-down pressure by generalist and specialist natural enemies in relation to habitat heterogeneity and resource availability
Bellone D, Björkman C & Klapwijk MJ (2020) 
Basic and Applied Ecology, 43: 16-26.

Tri‐trophic interactions: bridging species, communities and ecosystems
Abdala‐Roberts L, Puentes A, Finke DL, Marquis RJ, Montserrat M, Poelman EH, Rasmann S, Sentis A, van Dam NM, Wimp G, Mooney K & Björkman C  (2019)       Ecology Letters,

The tree species matters: Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce
Felton A, Petersson L, Nilsson O, Witzell J, Cleary M, Felton AM, Björkman C, Ode Sang Å, Jonsell M, Holmström E, Nilsson U, Rönnberg J, Kalén C & Lindbladh M  (2019) Ambio, DOI 10.1007/s13280-019-01259-x

Trait‐mediated indirect interactions: Moose browsing increases sawfly fecundity through plant‐induced responses
Nordkvist M, Klapwijk M, Edenius L, Gershenzon J, Schmidt A & Björkman C  (2019) Ecology and Evolution, DOI: 10.1002/ece3.5581
"Insects get boost from pines chewed by moose" (Dispatch Front Ecol Environm doi:10.1002/fee.2103)

Identifying climate-sensitive infectious diseases in animals and humans in Northern regions 
Omazic A, Bylund H, Boqvist S, Högberg A, Björkman C, Tryland M, Evengård B, Koch A, Berggren C, Malogolovkin A, Kolbasov D, Pavelko N, Thierfelder T & Albihn A (2019) Acta Veterinaria Scandinavica, 61:53.

A systematic review on the effects of plant-feeding by omnivorous arthropods: time to catch-up with the mirid-tomato bias?
Puentes A, Stephan JG & Björkman C  (2018) Frontiers in Ecology and Evolution, 6: 218.

Capturing complexity: Forests, decision-making and climate change mitigation action
Klapwijk MJ, Boberg J, Bergh J, Bishop K, Björkman C, Ellison D, Felton A, Lidskog R, Lundmark T, Keskitalo ECH, Sonesson J, Nordin A, Nordström E-M, Stenlid J & Mårald E  (2018) Global Environmental Change, 52: 238-247.

Transient synchrony among populations of five foliage-feeding Lepidoptera
Klapwijk MJ, Walter J, Hirka A, Csóka G, Björkman C & Liebhold A  (2018) Journal of Animal Ecology, 87: 1058-168.

Habitat heterogeneity affects predation of European pine sawfly cocoons
Bellone D, Klapwijk MJ & Björkman C  (2017) Ecology and Evolution, DOI: 10.1002/ece3.3632

Methods to identify the prey of invertebrate predators in terrestrial field studies
Birkhofer K, Bylund H, Dalin P, Ferlian O, Gagic V, Hambäck PA, Klapwijk M, Mestre L, Roubinet E, Schroeder M, Stenberg JA, Porcel M, Björkman C & Jonsson M  (2017) Ecology and Evolution, 7: 1942-1953.

Costs and benefits of omnivore-mediated plant protection: effects of plant-feeding on Salix growth more detrimental than expected
Puentes A & Björkman C  (2017) Oecologia, 184: 485-496.

Forest restoration as a double-edged sword: the conflict between biodversity conservation and pest control
Kärvemo S, Björkman C, Johansson T, Weslien J & Hjältén J  (2017) Journal of Applied Ecology, doi: 10.1111/1365-2664.12905.

Enhanced leaf nitrogen status stabilizes omnivore population density
Liman A-S, Dalin P & Björkman C  (2017) Oecologia, 183: 57-65.

Predator refuges for conservation biological control in intermediately disturbed systems: the rise and fall of a simple solution
Liman A-S, Eklund K & Björkman C  (2016) Journal of Applied Ecology, 53: 1823-1830. (Selected for blog post at J Appl Ecol)

Forest management and biocontrol of insect pests
Klapwijk MJ, Bylund H, Schroeder M & Björkman C  (2016) Forestry, doi:10.1093/forestry/cpw019.

Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden
Felton A, Nilsson U, Sonesson J, Felton A, Roberge J-M, Ranius T, Ahlström M, Bergh J, Björkman C, Boberg J, Drössler L, Fahlvik N, Gong P, Holmström E, Keskitalo CH, Klapwijk MJ, Laudon H, Lundmark T, Niklasson M, Nordin A, Pettersson M, Stenlid J, Sténs A & Wallertz K  (2016) Ambio 45(Suppl. 2): S124-139.

How far away is the next basket of eggs? Spatial memory and perceived cues shape aggregation patterns in a leaf beetle
Stephan J, Stenberg JA & Björkman C  (2015) Ecology 96: 908-914.

Climate Change and Insect Pests
Björkman C & Niemelä P (eds)  (2015)  CABI Climate Change Series 8

Forest management to mitigate insect damage in a changing climate: possibilities and uncertainties
Björkman C, Bylund H, Nilsson U, Nordlander G & Schroeder M  (2015)  In Climate Change and Insect Pests ed. by Björkman and Niemelä. CABI Climate Change Series 8

Optimizing crops for biocontrol of pests and disease
Stenberg JA, Heil M, Åhman I & Björkman C  (2015) Trends in Plant Science, doi: 10.1016/j.tplants.2015.08.007.  [LINK]

Temperature affects insect outbreak risk through tritrophic interactions mediated by plant secondarycompounds
Kollberg I, Bylund H, Jonsson T, Schmidt A, Gershenzon J & Björkman C  (2015)  Ecosphere 6(6):102.

Regulation of forest defoliating insects through small mammal predation: reconsidering the mechanisms
Kollberg I, Bylund H, Huitu O & Björkman C  (2014)  Oecologia DOI 10.1007/s00442-014-3080-x.

Forest insects and climate change: long-term trends in herbivore damage
Klapwijk MJ, Csóka G, Hirka A & Björkman C  (2013) Ecology and Evolution doi: 10.1002/ece3.717 [PDF]


CV including List of Publications

Future Forests

CLINF - Climate-change effects on the epidemiology of infectious diseases and the impacts on Northern Societies

The Linnean Centre for Plant Biology Uppsala

Leaf beetles on willows


Professor at the Department of Ecology; S, Forest entomology unit
Telephone: +4618671532, +46705581532
Postal address:
Inst för Ekologi, Box 7044
750 07 UPPSALA
Visiting address: Ulls Väg 16, Uppsala