Growth of crustose lichens: a review


Crustose species are the slowest growing of all lichens. Their slow growth and longevity, especially of the yellow-green Rhizocarpon group, has made them important for surface-exposure dating (‘lichenometry’). This review considers various aspects of the growth of crustose lichens revealed by direct measurement including: 1) early growth and development, 2) radial growth rates (RGR, mm yr-1), 3) the growth rate-size curve, and 4) the influence of environmental factors. Many crustose species comprise discrete areolae that contain the algal partner growing on the surface of a non-lichenised fungal hypothallus. Recent data suggest that ‘primary’ areolae may develop from free-living algal cells on the substratum while ‘secondary’ areolae develop from zoospores produced within the thallus. In more extreme environments, the RGR of crustose species may be exceptionally slow but considerably faster rates of growth have been recorded under more favourable conditions. The growth curves of crustose lichens with a marginal hypothallus may differ from the ‘asymptotic’ type of curve recorded in foliose and placodioid species and the latter are characterized by a phase of increasing RGR to a maximum and may be followed by a phase of decreasing growth. The decline in RGR in larger thalli may be attributable to a reduction in the efficiency of translocation of carbohydrate to the thallus margin or to an increased allocation of carbon to support mature ‘reproductive’ areolae. Crustose species have a low RGR accompanied by a low demand for nutrients and an increased allocation of carbon for stress resistance; therefore enabling colonization of more extreme environments.

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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:
Uncontrolled Keywords: radial growth rate,thallus development,growth curve,lichenometry,Geology,Geography, Planning and Development
Publication ISSN: 1468-0459
Last Modified: 06 Dec 2023 09:21
Date Deposited: 16 Sep 2010 13:52
Full Text Link: http://nora.ner ... id/eprint/10283
10.1111/j.1468- ... 59.2010.00374.x
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
http://onlineli ... 0374.x/abstract (Publisher URL)
PURE Output Type: Article
Published Date: 2010-03-01
Authors: Armstrong, Richard A. (ORCID Profile 0000-0002-5046-3199)
Bradwell, Tom



Version: Accepted Version

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