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Seasonal variation in Norway spruce response to inoculation with bark beetle-associated bluestain fungi one year after a severe drought

Ohrn, Petter and Berlin, Mats and Elfstrand, Malin and Krokene, Paal and Jonsson, Anna Maria (2021). Seasonal variation in Norway spruce response to inoculation with bark beetle-associated bluestain fungi one year after a severe drought. Forest Ecology and Management. 496 , 119443
[Research article]

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Abstract

In 2018, up to 4 million m3 Norway spruce was killed by the spruce bark beetle Ips typographus in Sweden. The event was unique for Sweden, in terms of both affected volume and the fact that it was triggered by severe drought stress, not by ample availability of relatively defenseless storm-felled trees. The outbreak continued in 2019 and 2020, each year with twice as many trees killed as in 2018. The aim of this study was to quantify seasonal variation and potential lag-effects in tree defense capacity the year after a severe drought stress. Inoculation with a bark beetle-associated bluestain fungus, repeated four times with one-month-intervals between May and August 2019, were carried out at three field sites with spruce provenances of Swedish and East European origin representing early and late bud burst, respectively. All sites had experienced moderate to severe drought stress in 2018, and site-specific defense capacity correlated positively with the cumulative precipitation two months before inoculation. Sites with two-month precipitation levels <100 mm had larger necrotic lesions in the phloem following inoculation, an indication of lower tree defense capacity. Lesion size did not differ between provenances, and all trees were able to confine fungal infection successfully. There were some seasonal differences in necrotic lesion size, with the sites Ska & uml;rsna & uml;s and Norberg having significantly larger lesions in June than in May, and site Lugnet having large lesions also in May. Lesions were generally smaller in July and August than in June. The cross-sectional area and number of traumatic resin ducts was measured in sapwood samples from one site, Lugnet, to quantify an additional aspect of tree defenses. The area of resin ducts produced in May and June were larger than that in July and August. This is in line with a positive correlation between lesion area and resin duct area, indicating that a stronger fungal infection following inoculation in spring triggered a stronger induced defense response. The East European provenances had more resin ducts than Swedish provenances, but the area of resin ducts did not differ significantly between provenances.

Authors/Creators:Ohrn, Petter and Berlin, Mats and Elfstrand, Malin and Krokene, Paal and Jonsson, Anna Maria
Title:Seasonal variation in Norway spruce response to inoculation with bark beetle-associated bluestain fungi one year after a severe drought
Series Name/Journal:Forest Ecology and Management
Year of publishing :2021
Volume:496
Article number:119443
Number of Pages:10
Publisher:ELSEVIER
ISSN:0378-1127
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Keywords:Picea abies, Grosmannia europhioides
URN:NBN:urn:nbn:se:slu:epsilon-p-113137
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-113137
Additional ID:
Type of IDID
DOI10.1016/j.foreco.2021.119443
Web of Science (WoS)000672641800001
ID Code:25079
Faculty:S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: SLUpub Connector
Deposited On:27 Aug 2021 13:25
Metadata Last Modified:27 Aug 2021 13:31

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