Within-site variation in lichen growth rates and its implications for direct lichenometry

Richard A. Armstrong

Research output: Contribution to journalArticle

Abstract

Variation in lichen growth rates poses a significant challenge for the application of direct lichenometry, i.e. the construction of lichen dating curves from direct measurement of growth rates. To examine the magnitude and possible causes of within-site growth variation, radial growth rates (RaGRs) of thalli of the fast-growing foliose lichen Melanelia fuliginosa ssp. fuliginosa (Fr. ex Duby) Essl. and the slow-growing crustose lichen Rhizocarpon geographicum (L.) DC. were studied on two S-facing slate rock surfaces in north Wales, UK using digital photography and an image analysis system (Image-J). RaGRs of M. fuliginosa ssp. fuliginosa varied from 0.44 to 2.63 mmyr-1 and R. geographicum from 0.10 to 1.50 mmyr-1.5. Analysis of variance suggested no significant variation in RaGRs with vertical or horizontal location on the rock, thallus diameter, aspect, slope, light intensity, rock porosity, rock surface texture, distance to nearest lichen neighbour or distance to vegetation on the rock surface. The frequency distribution of RaGR did not deviate from a normal distribution. It was concluded that despite considerable growth rate variation in both species studied, growth curves could be constructed with sufficient precision to be useful for direct lichenometry.

LanguageEnglish
Pages217-226
Number of pages10
JournalGeografiska Annaler: Series A
Volume96
Issue number2
Early online date14 Mar 2014
DOIs
Publication statusPublished - 30 Jun 2014

Fingerprint

lichenometry
lichen
rock
frequency distribution
slate
growth curve
systems analysis
photography
analysis of variance
light intensity
variance analysis
image analysis
texture
porosity
cause
vegetation

Keywords

  • direct lichenometry
  • growth variation
  • melanelia fuliginosa ssp. fuliginosa (Fr. ex Duby) Essl.
  • normal distribution
  • radial growth rate (RaGR)
  • rhizocarpon geographicum (L.) DC.

Cite this

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abstract = "Variation in lichen growth rates poses a significant challenge for the application of direct lichenometry, i.e. the construction of lichen dating curves from direct measurement of growth rates. To examine the magnitude and possible causes of within-site growth variation, radial growth rates (RaGRs) of thalli of the fast-growing foliose lichen Melanelia fuliginosa ssp. fuliginosa (Fr. ex Duby) Essl. and the slow-growing crustose lichen Rhizocarpon geographicum (L.) DC. were studied on two S-facing slate rock surfaces in north Wales, UK using digital photography and an image analysis system (Image-J). RaGRs of M. fuliginosa ssp. fuliginosa varied from 0.44 to 2.63 mmyr-1 and R. geographicum from 0.10 to 1.50 mmyr-1.5. Analysis of variance suggested no significant variation in RaGRs with vertical or horizontal location on the rock, thallus diameter, aspect, slope, light intensity, rock porosity, rock surface texture, distance to nearest lichen neighbour or distance to vegetation on the rock surface. The frequency distribution of RaGR did not deviate from a normal distribution. It was concluded that despite considerable growth rate variation in both species studied, growth curves could be constructed with sufficient precision to be useful for direct lichenometry.",
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Within-site variation in lichen growth rates and its implications for direct lichenometry. / Armstrong, Richard A.

In: Geografiska Annaler: Series A, Vol. 96, No. 2, 30.06.2014, p. 217-226.

Research output: Contribution to journalArticle

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