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Stein Åslund, Matilda, 2020. A window to the future of Sweden’s pine forestry? : development of declining Scots pine after a severe drought and the presence of Diplodia sapinea. Second cycle, A2E. Uppsala: SLU, Dept. of Forest Mycology and Plant Pathology

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Abstract

Swedish forestry is dominated by uniform conifer stands, a structure generally more susceptible to biotic and abiotic stressors. Among the agents causing forest decline, pathogenic fungi have the most substantial impact. This thesis presents an example of a “disease triangle”; the interaction between Scots pine, the fungus Diplodia sapinea, and the environmental aspects affecting them.
Scots pine has low demands on nutrient and water supply and is a strong competitor in poor soils. D. sapinea causes Diplodia shoot blight, a common pine disease that can lead to severe damages. The fungus is particularly infectious when the weather is wet and warm, and when the trees experience stress.
The study focuses on Gotland, an island where D. sapinea was found in connection to a severe drought period in 2018. The aims were to identify drivers of and monitor the decline in Scots pine on four symptomatic and four asymptomatic sites on the island, by estimating defoliation levels, assessing D. sapinea spore release, and analysing the local climate at the sites during one year after the drought period, as well as testing correlations of the decline with soil properties.
Trees with a high level of defoliation just after the drought period experienced a larger increase in defoliation the following year than trees with initially low defoliation levels. Trees did generally not recover during the experimental period. The spore load was overall higher at symptomatic sites, but the difference between site types by season was only significant in summer. The spore load was positively correlated to precipitation and wind speed. Relative humidity was overall higher at asymptomatic sites, and asymptomatic sites experienced less extreme temperatures. The soil type differed between the site types, although soil analyses showed no significant differences between asymptomatic and symptomatic sites regarding nutrients, pH, loss on ignition and water-holding capacity.
Conclusively, this study shows that the decline in Scots pine related to D. sapinea is strongly driven by drought stress and that an inadequate site may be what enables a disease triangle to be complete.

Main title:A window to the future of Sweden’s pine forestry?
Subtitle:development of declining Scots pine after a severe drought and the presence of Diplodia sapinea
Authors:Stein Åslund, Matilda
Supervisor:Stenlid, Jan and Brodde, Laura and Elfstrand, Malin
Examiner:Engelbrecht Clemmensen, Karina
Series:UNSPECIFIED
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2020
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:NK001 Biology and Environmental Science - Bachelor's Programme 180 HEC
Supervising department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
Keywords:Pinus sylvestris, Scots pine, Diplodia sapinea, Sphaeropsis sapinea, Diplodia pinea, drought, climate change
URN:NBN:urn:nbn:se:slu:epsilon-s-16085
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-16085
Subjects:Pests of plants
Forestry - General aspects
Forest injuries and protection
Language:English
Deposited On:25 Sep 2020 11:24
Metadata Last Modified:26 Sep 2020 01:00

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