The use of lichen growth rings in lichenometry: some preliminary findings

Abstract

Certain species of crustose lichens have concentrically zoned margins which probably represent yearly growth rings. These marginal growth rings offer an alternative method of studying annual growth fluctuations, establishing growth rate-size curves, and determining the age of thalli for certain crustose species. Hence, marginal growth rings represent a potentially valuable, unexploited, tool in lichenometry. In a preliminary study, we measured the widths of the successive marginal rings in 25 thalli of Ochrolechia parella (L.) Massal., growing at a maritime site in north Wales. Mean ring widths of all thalli varied from a minimum of 1.02 mm (the outermost ring) to a maximum of 2.06 mm (the third ring from the margin). There is some suggestion that marginal ring width and thallus size are positively correlated; and hence that growth rates increase in larger thalli in this small population. In a further study on recently exposed bedrock adjacent to Breidalon, SE Iceland, we examined the potential for using marginal growth rings to estimate thallus age of a lichen tentatively identified as a Rhizocarpon (possibly R. concentricum (Davies) Beltram.) and thus confirm the timing of surface exposure (c. 50 years). Collectively, these results suggest: 1) the measurement of marginal rings is a possible alternative method of studying the growth of crustose lichens; 2) O. parella may grow differently to other crustose species, exhibiting a rapidly increasing radial growth rate in thalli >40 mm; 3) where lichens with marginal rings grow on recently exposed surfaces (<60 yrs), minimum age estimates can be made using growth rings as an in situ indication of lichen growth rate; 4) it is suggested that this phenomenon could provide a valuable, previously unexploited, in situ lichenometric-dating tool in areas lacking calibration control.

Publication DOI: https://doi.org/10.1111/j.1468-0459.2010.00383.x
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
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
College of Health & Life Sciences > Clinical and Systems Neuroscience
Additional Information: This is an Accepted Manuscript of an article published by Taylor & Francis Group in Geografiska Annaler: Series A, Physical Geography in 2010, available online at: http://www.tandfonline.com/10.1111/j.1468-0459.2010.00383.x
Uncontrolled Keywords: Ochrolechia parella (L.) Massal,Rhizocarpon,marginal growth ring,radial growth rate,age–size curve,lichen-dating,Geology,Geography, Planning and Development
Publication ISSN: 1468-0459
Last Modified: 02 Jan 2024 18:10
Date Deposited: 16 Sep 2010 13:56
Full Text Link: http://nora.ner ... d/eprint/10287/
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
http://onlineli ... 0383.x/abstract (Publisher URL)
PURE Output Type: Article
Published Date: 2010-03
Authors: Armstrong, Richard A. (ORCID Profile 0000-0002-5046-3199)
Bradwell, Tom

Download

[img]

Version: Accepted Version

| Preview

Export / Share Citation


Statistics

Additional statistics for this record