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A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean / NEIL MATTHEWS

Swansea University Author: NEIL MATTHEWS

DOI (Published version): 10.23889/SUThesis.69249

Abstract

Chronic Oak Decline (COD) is a disease complex with multiple biotic and abiotic causal factors. UK natural oak woodland has a long history of recurrent oak decline outbreaks, however, an increase inseverity and frequency of decline, along with the spread of an acute complex, combine to pose a signif...

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Published: Swansea University, Wales, UK 2025
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Gagen, M. H.
URI: https://cronfa.swan.ac.uk/Record/cronfa69249
first_indexed 2025-04-10T10:11:05Z
last_indexed 2025-04-11T05:22:33Z
id cronfa69249
recordtype RisThesis
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spelling 2025-04-10T11:15:24.4977006 v2 69249 2025-04-10 A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean 3e3f3ed4ce2b2cec027565fa735ab801 NEIL MATTHEWS NEIL MATTHEWS true false 2025-04-10 Chronic Oak Decline (COD) is a disease complex with multiple biotic and abiotic causal factors. UK natural oak woodland has a long history of recurrent oak decline outbreaks, however, an increase inseverity and frequency of decline, along with the spread of an acute complex, combine to pose a significant threat to oak in the UK. This thesis hypothesises that, as COD outbreaks are periodic, tree ring histories in currently symptomatic and healthy trees would give insight into the disease complex. Two cohorts of Quercus robur L. (control and symptomatic) found in plantations of two differing ages at sites in the Forest of Dean were sampled for ring width and stable isotope dendrochronology. Speculation Cannop (SC), is a plantation of Napoleonic aged oak established from 1811 to supply the Royal Navy dockyards with timber. Chestnuts Wood (CW) was established in the 1950’s on an ancient woodland site. A novel method of crown classification assessed tree health in the studied cohorts. Tree ring widths were measured and cross dated using standard methodologies to construct chronologies for the two cohorts at both sites. Basal Area Increment (BAI) was also calculated to consider age related trends. A statistical Change Point Test was devised for determining step changes in tree ring growth that might be past points of decline in the tree ring records. Stable carbon and oxygen isotope analysis was carried out on a subsample of trees at each site. Event years were determined from pointer year analysis and a modified Abrupt Growth Change method and growth (via BAI) compared pre and post event year. Carbon and oxygen isotope ratios were likewise compared across event years. Significant differences in ring width, growth parameters height and diameter at breast height (DBH), and carbon isotope series were observed between the control and symptomatic cohorts at both sites. The summer source water signal, known todominate variability in UK oak stable isotope time series, masked any conclusive decline history in the stable oxygen isotope series. Insect defoliation events were inferred from the ring width series and the effect of successive episodes discussed in relation to development of decline at both sites. Dendrochronological histories can give useful insight into past decline episodes to aid understanding of how different trees are likely to respond to current and future outbreaks. E-Thesis Swansea University, Wales, UK Dendrochronology, Chronic Oak Decline, Quercus robur 14 1 2025 2025-01-14 10.23889/SUThesis.69249 A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information COLLEGE NANME COLLEGE CODE Swansea University Gagen, M. H. Doctoral Ph.D Woodland Heritage Woodland Heritage 2025-04-10T11:15:24.4977006 2025-04-10T11:02:19.3185900 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Geography NEIL MATTHEWS 1 69249__33980__3d99997663e5415981c97a2a736db35e.pdf 2024_Matthews_N.final.69249.pdf 2025-04-10T11:09:45.8070935 Output 8587539 application/pdf E-Thesis – open access true Copyright: The Author, Neil Matthews, 2024 true eng
title A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
spellingShingle A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
NEIL MATTHEWS
title_short A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
title_full A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
title_fullStr A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
title_full_unstemmed A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
title_sort A dendrochronological approach to the study of Chronic Oak Decline in the Forest of Dean
author_id_str_mv 3e3f3ed4ce2b2cec027565fa735ab801
author_id_fullname_str_mv 3e3f3ed4ce2b2cec027565fa735ab801_***_NEIL MATTHEWS
author NEIL MATTHEWS
author2 NEIL MATTHEWS
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publishDate 2025
institution Swansea University
doi_str_mv 10.23889/SUThesis.69249
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Geography{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Geography
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description Chronic Oak Decline (COD) is a disease complex with multiple biotic and abiotic causal factors. UK natural oak woodland has a long history of recurrent oak decline outbreaks, however, an increase inseverity and frequency of decline, along with the spread of an acute complex, combine to pose a significant threat to oak in the UK. This thesis hypothesises that, as COD outbreaks are periodic, tree ring histories in currently symptomatic and healthy trees would give insight into the disease complex. Two cohorts of Quercus robur L. (control and symptomatic) found in plantations of two differing ages at sites in the Forest of Dean were sampled for ring width and stable isotope dendrochronology. Speculation Cannop (SC), is a plantation of Napoleonic aged oak established from 1811 to supply the Royal Navy dockyards with timber. Chestnuts Wood (CW) was established in the 1950’s on an ancient woodland site. A novel method of crown classification assessed tree health in the studied cohorts. Tree ring widths were measured and cross dated using standard methodologies to construct chronologies for the two cohorts at both sites. Basal Area Increment (BAI) was also calculated to consider age related trends. A statistical Change Point Test was devised for determining step changes in tree ring growth that might be past points of decline in the tree ring records. Stable carbon and oxygen isotope analysis was carried out on a subsample of trees at each site. Event years were determined from pointer year analysis and a modified Abrupt Growth Change method and growth (via BAI) compared pre and post event year. Carbon and oxygen isotope ratios were likewise compared across event years. Significant differences in ring width, growth parameters height and diameter at breast height (DBH), and carbon isotope series were observed between the control and symptomatic cohorts at both sites. The summer source water signal, known todominate variability in UK oak stable isotope time series, masked any conclusive decline history in the stable oxygen isotope series. Insect defoliation events were inferred from the ring width series and the effect of successive episodes discussed in relation to development of decline at both sites. Dendrochronological histories can give useful insight into past decline episodes to aid understanding of how different trees are likely to respond to current and future outbreaks.
published_date 2025-01-14T05:27:40Z
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