Lihhenomeetria, I

LIHHENOMEETRIA – bioloogiline dateerimismeetod

Indikatsiooniökoloogia, Prof. J. Martin

Euroakadeemia

• Roland Beschel (1928-1971) – lihhenomeetria autor

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• Lichenometry is a bioindicational method that allows determining the relative and absolute age of the substrates on the basis of the thalli of the lichens settling on these substrates. Lichenometry was developed by the Austrian-Canadian botanist Roland Веschel (Beschel I950, I954, I955, I957a, b, I958a,bЬ, I959, I96I, I963a, b, I965 , I973; Beschel, Weidicк, I973).

• Lichens are considered to be slow growing plants. In the moderate climate conditions, the annual increment of crustose lichens is rarely over 1–2 mm

• (Smith, 1962); according to the data by M. Hale, 0.1~10 mm (Hale, 1961, 1973).

• Two methods are used for studying lichen increment:

• direct measurements at fixed time intervals during a certain time period

• the measurements of the lichens thalli on the substrates of a determined age.

• The method of lichenometric dating is based on the following assumptions:

• primarily outcropped surfaces (rocks, moraine material, building materials etc.) are originally not invaded by lichens;

• the invasion (colonisation, succession) of the primarily outcropped substrate (surface) begins at the moment of the emergence of this substrate;

• from the moment of invasion, the growth of lichens is subjected to certain regularities that allow forecasting the progress of growth; in the conditions of homogeneous macroclimate, the growth is a function of time that has passed from the moment of settlement.

• the interrelation between the diameters of the R. geographicum and the projective cover of synusiae on the moraines of the IGAN glacier (Polar Urals) is shown. The calculations show that the correlation is practically linear (r = 0.910, η = 0.916, t = 1.13 < 3, Р = 95 %). Thus, the indicator of the projective cover can be used for the relative dating both of the moraine formations and of succession stages.