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Christer Björkman

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

Multiple stressors of forest trees: interactions between moose and insects

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 
Kristina Berggren (2018- )
Dragos Cocos (2018- , co-supervisor)
Yayuan Chen (2017- )
Michelle Nordkvist (2016- )
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
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

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.

Mixed forests to mitigate increased risks for insects outbreaks
Klapwijk MJ & Björkman C (2018) Scandinavian Journal of Forest Research,

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.

General public acceptance of forest risk management strategies in Sweden: Comparing three approaches to acceptability
Eriksson L, Björkman C & Klapwijk MJ (2018) Environment and Behavior, DOI 10.1177/0013916517691325.

Roe deer prefer mixed-sex willow stands over monosexual stands but do not discriminate between male and female plants
Moritz KK, Parachnowitsch AL, Julkunen-Tiitto R, Björkman C, Ayres MP & Stenberg JA (2018) Environmental and Experimental Botany, 146: 62-67.

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.

Consumptive and nonconsumptive effect ratios depend on interaction between plant quality and hunting behavior of omnivorous predators
Stephan JG, Stenberg JA & Björkman C (2017) Ecology and Evolution, 7: 2327-2339.

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

Plant sex effects on insect herbivores and biological control in a Short Rotation Coppice willow
Moritz KK, Björkman C, Parachnowitsch AL & Stenberg JA (2017) Biological Control, 115: 30-36.

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.

Adaptation to climate change in Swedish forestry
Keskitalo CH, Bergh J, Felton A, Björkman C, Berlin M, Axelsson P, Ring E, Ågren A, Roberge J-M, Klapwijk MJ & Boberg J (2016) Forests 7(2), 28; doi:10.3390/f7020028.

Socio-ecological implications of modifying rotation lengths in forestry
Roberge J-M, Laudon H, Björkman C, Ranius T, Sandström C, Felton A, Sténs A, Nordin A, Granström A, Widemo F, Bergh J, Sonesson J, Stenlid J & Lundmark T (2016) Ambio 45 (Suppl. 2): S109-S123.

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.

Detectability of landscape effects on recolonization increases with regional population density
Liman A-S, Dalin P & Björkman C (2015) Ecology and Evolution 5: 2694-2702.

Phenotypic plasticity in a willow leaf beetle depends on host plant species: Release and recognition of beetle odors 
Austel N, Reinecke A, Björkman C, Hilker M & Meiners T (2015) Chemical Senses 40: 109-124. 

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.

Direct effects of elevated temperature on a tri-trophic system: Salix, leaf beetles and predatory bugs
Puentes A, Torp M, Weih M & Björkman C (2015)  Arthropod-Plant Interactions DOI 10.1007/s11829-015-9401-0.

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]

Identifying and managing the ecological risks of using introduced tree species in Sweden's production forestry
Felton A, Boberg J, Björkman C & Widenfalk O (2013) Forest Ecology and Management 307: 165-177. [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; Forest entomology unit
Telephone: 018-671532, 0705-581532
Postal address:
Inst för Ekologi, Box 7044
750 07 UPPSALA
Visiting address: Ulls Väg 16, Uppsala