Neighbours matter and the weak succumb: ash dieback infection is more severe in ash trees with fewer conspecific neighbours and lower prior growth rate

Cracknell, David ORCID logo ORCID: , Peterken, George ORCID logo ORCID: , Pommerening, Arne ORCID logo ORCID: , Lawrence, Peter ORCID logo ORCID: and Healey, John ORCID logo ORCID: (2023) Neighbours matter and the weak succumb: ash dieback infection is more severe in ash trees with fewer conspecific neighbours and lower prior growth rate. Journal of Ecology, 111 (10). pp. 2118-2133.

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The epidemiology and severity of ash dieback (ADB), the disease caused by the ascomycete fungus Hymenoscyphus fraxineus, has been linked to a variety of site conditions; however, there has been a lack of analysis at an individual tree scale. Symptoms of ADB were scored on ca. 400 trees of Fraxinus excelsior (ash) in permanent sample plots during two successive years in a UK natural woodland reserve. Using comprehensive plot records maintained since 1945, and detailed spatial records updated since 1977, we assembled an array of potential explanatory variables, including site environment factors, ash tree density, previous and present tree condition and near neighbourhood summary statistics (NNSS), such as species mingling and size dominance. Their impact on the severity of ADB of focal ash trees was tested with generalised linear mixed effects models (GLMM). The severity of ADB was much greater in the lower slope parts of the site with moister soils and least in a managed area subject to tree thinning in the previous 35 years. Severity of ADB had a negative association with focal ash tree prior relative growth rate over a period of a decade immediately before the disease was detected at the site. Greater ADB severity was also significantly associated with smaller diameter at breast height of ash trees. Additionally, ADB was significantly positively associated with a greater proportion of heterospecific trees amongst the six nearest neighbours of the focal tree. Synthesis. The relationship of the severity of ADB disease with site environment, tree condition and neighbourhood is complex but nevertheless important in the progression of the disease. The findings suggest some silvicultural interventions, such as thinning to increase the vigour of retained ash trees, might reduce the impact of ADB.

Item Type: Article
Journal / Publication Title: Journal of Ecology
Publisher: Wiley / British Ecological Society
ISSN: 1365-2745
Departments: Institute of Science and Environment > Forestry and Conservation
Additional Information: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Depositing User: Insight Administrator
SWORD Depositor: Insight Administrator
Date Deposited: 19 Sep 2023 15:00
Last Modified: 13 Jan 2024 15:31


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