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Research article2018Peer reviewedOpen access

Mixed forests to mitigate risk of insect outbreaks

Klapwijk, Maartje J.; Bjorkman, Christer

Abstract

The majority of agricultural and forest production systems are typically simplified systems and therefore thought to be sensitive to disturbance. Ecosystems might be less sensitive to disturbance if complexity increases. The resource concentration hypothesis predicts that complexity makes it more difficult for herbivores to find and exploit their food. The natural enemy hypothesis predicts less damage in diverse environments because enemy abundance and diversity remain higher and more stable in environments providing more alternative food sources. We explore the effect of tree diversity in two types of pine stands differing in tree diversity. We ask whether European pine sawfly (Neodiprion sertifer) larval group distribution and larval mortality, imposed by specialist natural enemies, is affected by tree diversity. We find fewer larval groups on pine trees surrounded by non-host trees, indicating that fewer egg-batches were laid. Mortality rates by specialist enemies are not affected by tree diversity but parasitism rates are likely to be higher in larger trees. Herbivores are inhibited by increased tree diversity and density, whereas natural enemies seem to be unaffected, partly increasing the resistance of more diverse forest stands against insect damage. Thus, managing for more mixed forests could mitigate risk of herbivore damage.

Keywords

Heterogeneity; forest management; tree diversity; herbivory; insect outbreaks; temperature; outbreak; parasitism

Published in

Scandinavian Journal of Forest Research
2018, Volume: 33, number: 8, pages: 772-780
Publisher: TAYLOR & FRANCIS AS

      SLU Authors

      • Associated SLU-program

      Future Forests (until Jan 2017)
      SLU Plant Protection Network
      SLU Future Forests

      UKÄ Subject classification

      Forest Science
      Ecology

      Publication identifier

      DOI: https://doi.org/10.1080/02827581.2018.1502805

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/97096