'Growth rings' in crustose lichens:comparison with directly measured growth rates and implications for lichenometry


Some species of crustose lichens, such as Ochrolechia parella (L.) Massal., exhibit concentric marginal rings, which may represent an alternative technique of measuring growth rates and potentially, a new lichenometric dating method. To examine this hypothesis, the agreement and correlation between ring widths and directly measured annual radial growth rates (RaGR, mm a<sup>-1</sup>) were studied in 24 thalli of O. parella in north Wales, UK, using digital photography and image analysis. Variation in ring width was observed at different locations around a thallus, between thalli, and from year to year. The best agreement and correlation between ring width and lichen growth rates was between mean width of the outer two rings (measured in 2011) and mean RaGR (in 2009/10). The O. parella data suggest that mean width of the youngest two growth rings, averaged over a sample of thalli, is a predictor of recent growth rates and therefore could be used in lichenometry. Potential applications include as a convenient method of comparing lichen growth rates on surfaces in different environmental settings; and as an alternative method of constructing lichen growth-rate curves, without having to revisit the same lichen thalli over many years. However, care is needed when using growth rings to estimate growth rates as: growth ring widths may not be stable; ring widths exhibit spatial and temporal variation; rings may not represent 1-year's growth in all thalli; and adjacent rings may not always represent successive year's growth.

Publication DOI: https://doi.org/10.1016/j.quageo.2015.04.003
Dataset DOI: https://doi.org/10.17036/researchdata.aston.ac.uk.00000376
Divisions: College of Health & Life Sciences > School of Optometry > Optometry
College of Health & Life Sciences > School of Optometry > Optometry & Vision Science Research Group (OVSRG)
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
College of Health & Life Sciences > Clinical and Systems Neuroscience
Additional Information: © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords: annual variation,lichenometry,marginal growth ring,ochrolechia parella (L.) massal,radial growth rate,RaGR,Geology,Earth and Planetary Sciences (miscellaneous),Stratigraphy
Publication ISSN: 1878-0350
Full Text Link:
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015-06
Published Online Date: 2015-04-18
Authors: Armstrong, R.A. (ORCID Profile 0000-0002-5046-3199)
Bradwell, T.



Version: Accepted Version

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