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

Auteur(s) et Affiliation(s)



Description :
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). 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.


Type de document :
Article de périodique

Source :
Geografiska annaler. Series A. Physical geography, issn : 0435-3676, 2014, vol. 96, n°. 2, p. 217-226, nombre de pages : 10, Références bibliographiques : 50 ref.

Date :
2014

Editeur :
Pays édition : Suede, Stockholm, Svenska sällskapet för antropologi och geografi