Abstract

The contribution of non-lethal pathogenic attacks to tree death is still unclear. Manion's theory of the spiral of decline predicts that tree decline and death occurs because of a sequence of predisposing, inciting and contributing events. To understand whether pathogens can act as predisposing or inciting factors, we tested whether a sequence of non-lethal pathogen attacks causing crown defoliation could lead to a chronic decline in tree health and predispose trees to die. Scots pine (Pinus sylvestris) trees predisposed or escaping (non-predisposed) a first outbreak by the pathogen Gremmeniella abietina (predisposing event) were compared in terms of survival and susceptibility to secondary pests (contributing event) after a second G. abietina outbreak (inciting event). Four years after the inciting event, mortality among predisposed trees was up to five times higher than among trees escaping the first epidemic. Predisposed trees were twice as susceptible to secondary attacks by the common pine shoot beetle (Tomicus piniperda). Ten years after the inciting event, severely predisposed trees had not been able to restore their crowns and still showed stagnated growth. This study showed that pathogen-induced defoliation can act as predisposing and inciting factors for tree death, reducing the capacity of trees to survive short- or long-term stressing events, such as bark beetle attacks. We also showed that tree decline can result from a combination of predisposing and inciting events caused by pathogens. (C) 2016 Elsevier B.V. All rights reserved.

Keywords

Gremmeniella; Insect pest; Necrotroph; Prediposition; Tree disease; Tree mortality; Tomicus piniperda

Published in

Forest Ecology and Management
2016, Volume: 379, pages: 273-280
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Oliva Palau, Jonàs

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Stenlid, Jan

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Wahlström, Kjell

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Jonsson, Maria

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Drobyshev, Igor

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    
  • Université du Québec en Abitibi-Témiscamingue (UQAT)

• Stenström, Elna

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

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UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1016/j.foreco.2016.08.011

Permanent link to this page (URI)

https://res.slu.se/id/publ/80084